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Pacific salmon, the signature species of the Pacific Northwest, have declined across their range for well over a century, due to a myriad of human-caused effects on their habitat and the fish themselves. Restoration efforts--some successful, some halting--began in earnest in the late 20th century, with considerable attention focused on the Columbia Basin, where historically salmon runs were crippled by a large interconnected hydroelectric system of federal and non-federal dams. In the 1980 Northwest Power Act, Congress created an interstate agency, the Northwest Power and Conservation Council, with access to a substantial amount of ratepayer dollars; the agency has chosen to expend those dollars principally for habitat rehabilitation and hatchery production. Generic federal laws like the Clean Water Act and the Endangered Species Act have provided some levers to modify dam operations to benefit fish and driven better protections for salmon throughout the Northwest. The relicensing requirements of the Federal Power Act, coupled with that law's fish protection provisions, have led to several notable dam removals. Significant restoration in Puget Sound watershed is underway due to a judicial decision finding that barrier road culverts violate treaty fishing rights, an interpretation that holds potential to foster salmon habitat improvement measures throughout the Northwest. Surveying events from Alaska's Bristol Bay in the north to the Klamath River along the Oregon-California border in the south, we explain how the law has--and must--play a key role in efforts to save salmon. Although the importance of particular laws varies from basin to basin--as does their effectiveness--some significant restoration is underway despite major unanswered questions such as the fate of the lower Snake River dams. The institution of tribal co-management programs, especially along the Oregon coast, provide an especially significant restoration tool if this development can be replicated across salmon country. The addition of tribal sovereigns into decision-making is likely to improve salmon protection and restoration wherever comanagement programs exist. Improved management will be a prerequisite if Pacific salmon are to recover in a climate-challenged world that threatens the existence of many runs. But to a large extent, restoring historic fish runs will require federal policies and leadership that have not always been present. As the first quarter of the 21st century draws to a close, salmon saving efforts are proceeding on a variety of fronts with some promising results, but the future of many salmon runs is clouded by the threat of climate change and a national ambivalence to confronting its challenges with a muscular response. [ABSTRACT FROM AUTHOR]

Fish spawning locations are a crucial input into fisheries management and conservation plans, and many stocks are especially sensitive to the environmental conditions within these localized zones. Globally collated data on spawning locations across many species has been unavailable, hindering global stock assessments and analyses of sustainable development and global environmental change. To address this, we created a geocoded fish spawning dataset using qualitative spawning information from FishBase and Science and Conservation of Fish Aggregations (SCRFA). We cleaned and geocoded the spawning locations of 1,045 marine fish species into 2,931 regions. Each spawning region is defined by one or more polygons, and most spawning regions are associated with spawning months. The resulting dataset covers oceans globally. This dataset will be useful to scientists studying marine fish population dynamics and their interactions with the physical environment on regional to large scales. [ABSTRACT FROM AUTHOR]

Hydropower operations significantly alter the natural hydrological conditions of rivers, exerting adverse effects on riverine ecosystems. Accurate identification of fish habitats under hydropower operation and maintaining suitable ecological flow are crucial for riverine ecological conservation and water resource management. Coreius guichenoti was selected as the target species and the Yibin reach of the downstream Jinsha River was selected as the studied river reach. Subsequently, Weighted Usable Area (WUA) and Habitat Connectivity Index (HCI) were employed to comparatively analyze the habitat quantity and quality before and after the construction and operation of the Xiangjiaba hydropower station, namely the natural period (1991–2005), construction period (2006–2014), and operation period (2015–2020). Finally, correlations between WUA, HCI, and flow were established to determine the optimal ecological flow corresponding to optimal fish habitats. The results indicate that the average WUA and HCI during the construction period are similar to the natural period. In comparison to the natural period, the average WUA decreases by 9.2%, and the average HCI decreases by 0.05 during the operation period. It is determined that the habitat conditions are optimal when the flow is between 3000 and 5000 m3/s. After further refining the flow scenarios, the suitable ecological flow is determined to be 3500 m3/s. This study can provide a scientific basis for the water resources management in the Jinsha River and contribute to the field of riverine ecological conservation and restoration. [ABSTRACT FROM AUTHOR]

The Assamese snake-head fish, Channa stewartii (Playfair, 1867) is endemic to the Brahmaputra River Basin (upper, middle, and lower) in India and Bangladesh, as well as the Ganges River basin extending from southern Nepal south-eastward. This study aimed to examine the taxonomic status and the length-weight relationship and condition factor of C. stewartii populations from a newly found community in Assam, Morigaon district, India. Taxonomic assessment involves morphological examination and comparison with existing literature to confirm the species identity. The morphological observation clearly indicated that C. stewartii specimens were distinguished by their blue fins with black patches, red fin edges, and reddish-pink pectoral fins. The female fishes have slightly duller, yellowish colours than the males, although they still have brighter colours than the males. Phylogenetic analyses also showed that our recent collection was clustered with C. stewartii from Assam, India. Measurements of C. stewartii length-weight relationship exhibited that both male (b = 3.389) and female (b = 3.396) showed a positive allometric growth. Additionally, the condition factor (K) for both sexes exceeded 1, indicating the well-being and health of the fish in their habitat. The findings contribute to the understanding of the ecological characteristics and population dynamics of C. stewartii in Morigaon district, providing valuable information's for fisheries management and conservation efforts in the region. [ABSTRACT FROM AUTHOR]

With increasing emphasis on ecological environment conservation, the conservation of fish habitat and the regional carbon balance need to be incorporated into the operation process of reservoirs. In this research, formulas for calculating ecological and environmental objectives in reservoir operation were obtained by fitting the curve of discharge and fish habitat area and comprehensively analysing the factors affecting reservoir carbon emissions. Additionally, we used the multi-objective optimization algorithm NSGA-II-DE to study the competitive relationship between the economic, ecological, and environmental benefits of the Longtoushi Reservoir and proposed a relatively optimized operation scheme using the multi-objective decision-making method VIKOR. The results of this scheme showed that the power generation, weighted usable area (WUA) and carbon emissions of Longtoushi Reservoir during the study period were 5.74 × 108 kW h, 9.61 × 104 m2 and 51.32 t, respectively. Compared with the relative optimal operation scheme, the power generated by the maximum power generation scheme increased by 2.66%, the WUA decreased by 1.68%, and carbon emissions increased by 9.86%; the power generation of the maximum WUA scheme increased by 0.16%, the WUA decreased by 0.08%, and carbon emissions increased by 0.72%; and the power generation of the minimum carbon emission scheme increased by 3.14%, the WUA decreased by 1.62%, and the carbon emissions increased by 9.14%. In general, competition between power generation, WUA and carbon emissions is inevitable, and reducing the water level in reservoirs can effectively increase ecological and environmental benefits. [ABSTRACT FROM AUTHOR]

River damming has brought great benefits to flood mitigation, energy and food production, and will continue to play a significant role in global energy supply, particularly in Asia, Africa, and South America. However, dams have extensively altered global river dynamics, including riverine connectivity, hydrological, thermal, sediment and solute regimes, and the channel morphology. These alterations have detrimental effects on the quality and quantity of fish habitat and associated impacts on aquatic life. Indeed, dams have been implicated in the decline of numerous fishes, emphasizing the need for effective conservation measures. Here, we present a global synthesis of critical issues concerning the impacts of river damming on physical fish habitats, with a particular focus on key fish species across continents. We also consider current fish conservation measures and their applicability in different contexts. Finally, we identify future research needs. The information presented herein will help support sustainable dam operation under the constraints of future climate change and human needs. Plain Language Summary: River damming yields great social‐economic benefits, but also causes significant eco‐environmental impacts, particularly on fish. Dams block fish migration routes, alter hydrological and water temperature regimes, and modify channel morphology. These changes impact fish physical habitats and associated communities. Here, we synthesize the impacts of river damming on fish physical habitats, and review potential conservation measures that could be used to off‐set or mitigate the impacts of dams on fish habitats, populations and communities. Key Points: Dam construction alters river hydro‐geomorphological conditions and hence influences fish habitat quality and quantityKnowledge of river hydrogeomorphology and reservoir properties can inform which conservation measures may benefit fish conservationLong‐term monitoring is needed to understand causal effects and synergies with climate change [ABSTRACT FROM AUTHOR]

Riffle‐pool constructions are common practice in river management and fish conservation, but insufficient science exists to guide objective design of riffle‐pool. Understanding the spatial design of a riffle‐pool in river systems has significant value because it can provide important information to ameliorate aquatic species decline. In this study, six types of riffle‐pool structures were designed to assess hydrodynamic and riverbed morphology effects on stream habitat status. A two‐dimensional ecohydraulic model was used to assess the roles of different riffle‐pool designs in river habitat conditions. The natural flow condition and three types of flood flow conditions were applied to the six types of riffle‐pool structures to evaluate the habitat quality and the sustainability of the riffle‐pool design in mountain rivers. The long‐term impacts of the hydrodynamic and hydromorphology conditions on river physical habitat status were also analysed. The results indicate substantial differences in habitat quality among six riffle‐pool structures. It was found that narrow riffle‐pool construction yielded the best performance for the fish habitat, which had the best habitat quality among six riffle‐pool designs with the smallest pool area. In the same riffle‐pool structure, the habitat suitability in the riffle‐pool sequence will primarily increase more rapidly and then decrease gradually along with the discharge increase. Under the flood discharge scenarios, low flood discharge could improve riffle‐pool habitat quality, while high flood discharge could fragment the riffle‐pool habitat quality further. The long‐term hydrodynamic conditions have the same effects on all six cases. Overall, low discharge and smaller pool design would be beneficial to the river system, which could help maintain habitat diversity of mountain rivers. This analysis could provide valuable information for river management and decision‐making, which could assist in designing better mountain river habitats to promote conservation and rehabilitation of endangered biota. [ABSTRACT FROM AUTHOR]

Vegetation changes in saltmarsh habitat can influence fish assemblages and abundance. In Tasmania, Australia, mid‐latitude succulent saltmarsh communities have been invaded by the introduced tall grass, Spartina anglica. Eradication efforts have been ongoing since the 1990s with purported benefits for fish access to intertidal foraging grounds, but a lack of knowledge of the impact of S. anglica on fish limits understanding of the benefits and effectiveness of native habitat restoration. Here, we investigate whether fish assemblages in native saltmarshes and non‐native S. anglica grassland differ in species diversity, fish abundance, and size class distribution. We used buoyant pop nets to sample fishes in Sarcocornia quinqueflora herbland and S. anglica grassland swards at three sampling stations in northwest Tasmania. Very few individuals and low species diversity were recorded in both vegetation types at the sampling station with the most well‐established S. anglica infestation. Elsewhere, richness and diversity were higher in S. quinqueflora herbland. Overall fish abundance was higher in S. quinqueflora than in S. anglica, with a very strong effect at one sampling station. Fewer small individuals of the numerically dominant Atherinosoma microstoma were recorded in S. anglica, potentially indicating impaired nursery function. Our results provide important insights for S. anglica control, as we are the first to demonstrate a relationship between S. anglica presence and fish characteristics in southern Australian saltmarsh. These results indicate that S. anglica control is valuable for fish conservation. An extension of our research to document the effects of S. anglica removal on fishes is desirable. [ABSTRACT FROM AUTHOR]

In this study, the distribution and some diagnostic features of the endemic Garra culiciphaga belonging to the Cyprinidae family in the Ceyhan River systems were determined. Accordingly, the average total length of G. culiciphaga individuals is 49.58 mm, and their average weight is 1.32 g. Line lateral scales are 30-33, line transversal 8/7, and pharyngeal teeth are 3.3.5-5.3.3. G. culiciphaga has a very limited distribution in the Ceyhan River basin and has been identified from the Kumaşır Lake, Aksu Stream and Akçasu Stream. However, G. culiciphaga individuals were detected in May 2015 in Aksu stream could not encountered in the following year (April 2016) due to habitat loss. [ABSTRACT FROM AUTHOR]

Effective conservation of stream fishes and their habitats is complicated by the fact that human stressors alter the way in which natural factors such as stream size, catchment geology, and regional climate influence stream ecosystems. Consequently, efforts to assess the condition of stream fishes and their habitats must not only attempt to characterize the effects of human stressors but must account for the effects of natural influences as well. This study is an assessment of all stream fish habitats in the Mississippi River basin, USA. The basin supports over 400 stream fish species, drains a land area of 3.2 M km2, and includes a myriad of human stressors such as intensive agriculture, urbanization, nutrient loading, and habitat fragmentation by dams and road/stream crossings. To effectively characterize types and levels of human stressors specifically impacting the basin's stream fish species, our assessment approach first accounted for the influence of natural landscape conditions on species abundances with multiple steps, including stratifying our analyses by region and stream size and quantitatively modeling the influences of natural factors on stream fishes. We next quantified individual fish species responses to explicit human stressors for different measures of land use, fragmentation, and water quality, including summaries of measures in local vs. catchment extents. Results showed that many species had negative threshold responses to human stressors and that impacts varied by species, by region, and by the spatial extents in which stressors were summarized. Our spatially explicit results indicated the degree of stream reach impairment for specific stressor categories, for individual species, and for entire assemblages, all of which are types of information that can aid decision makers in achieving specific conservation goals in the region. [ABSTRACT FROM AUTHOR]

The lack of high‐resolution distribution maps for freshwater species across large extents fundamentally challenges biodiversity conservation worldwide. We devised a simple framework to delineate the distributions of freshwater fishes in a high‐resolution drainage map based on stacked species distribution models and expert information. We applied this framework to the entire Chinese freshwater fish fauna (>1600 species) to examine high‐resolution biodiversity patterns and reveal potential conflicts between freshwater biodiversity and anthropogenic disturbances. The correlations between spatial patterns of biodiversity facets (species richness, endemicity, and phylogenetic diversity) were all significant (r = 0.43–0.98, p < 0.001). Areas with high values of different biodiversity facets overlapped with anthropogenic disturbances. Existing protected areas (PAs), covering 22% of China's territory, protected 25–29% of fish habitats, 16–23% of species, and 30–31% of priority conservation areas. Moreover, 6–21% of the species were completely unprotected. These results suggest the need for extending the network of PAs to ensure the conservation of China's freshwater fishes and the goods and services they provide. Specifically, middle to low reaches of large rivers and their associated lakes from northeast to southwest China hosted the most diverse species assemblages and thus should be the target of future expansions of the network of PAs. More generally, our framework, which can be used to draw high‐resolution freshwater biodiversity maps combining species occurrence data and expert knowledge on species distribution, provides an efficient way to design PAs regardless of the ecosystem, taxonomic group, or region considered. [ABSTRACT FROM AUTHOR]

The offshore waters of the Yangtze Estuary are an important fish habitat, and the large gradient of environmental conditions leads to different fish assemblages. We studied the spatial and temporal variations in fish assemblages and their relationships with environmental factors in the offshore waters of the Yangtze Estuary during the autumns of 2012–2016. The fish assemblage consisted of 64 fish species from 39 families, of which 6 species were dominant. There were significant interannual differences in fish abundance, biomass, and species composition, with the highest abundance and biomass in 2013, the lowest abundance in 2016, and the lowest biomass in 2015. Redundancy analysis revealed that total suspended particles and dissolved oxygen drove interannual variation in fish abundance, biomass, and species composition, and depth drove spatial variation in the fish assemblage. According to the depth, the fish were classified as shallow assemblage and deep assemblage. Understanding the spatial and temporal patterns of fish assemblage in the offshore waters of the Yangtze Estuary is beneficial to the conservation of fish and the sustainable use of fishery resources in the offshore waters of the Yangtze Estuary. [ABSTRACT FROM AUTHOR]

Estuaries provide nursery habitats for a variety of fish species of different ecological guilds and have complicated environmental conditions. In this study, we applied ensemble species distribution models (SDMs) to four abundant and different ecological guild larval fish species (Hemiculter bleekeri (freshwater guild), Pseudolaubuca sinensis (freshwater guild), Coilia mystus (brackish water guild), and Engraulis japonicus (marine guild)) to explore their suitable habitats and the fish–habitat relationships in the Yangtze Estuary. The results showed that random forest (RF) demonstrated the best performance in all single algorithms and the surface range envelop (SRE) model was scarcely accurate. The ensemble SDMs demonstrated a superior predictive ability compared with any single algorithm, with the true skill statistic (TSS) and the area under the receiver operating characteristic curve (AUC) scores being above 0.899 and 0.641, respectively. Binary presence–absence maps showed the different spatial distribution patterns of the four species. We primarily found the freshwater species (P. sinensis and H. bleekeri) present in the South Branch (west of 122° E), whereas we found the marine species (E. japonicus) anywhere except inside the South Branch (west of 121.8° E). The area for P. sinensis (1615.93 km2) was relatively larger than that for H. bleekeri (1136.87 km2). We predicted that the brackish water species (C. mystus) would most likely be present inside the North Branch (west of 122° E), Eastern Chongming, and outside the South Branch (east of 121.8° E). Salinity, as a key environmental variable, contributed to the spatial variability. A low salinity (sea surface salinity (SSS) < 3) was beneficial for P. sinensis and H. bleekeri but was not suitable for E. japonicus. The SSS suitable range for C. mystus was 5–10 and 12–20. Multiple ecological guild species dwelled in the confluence of salt and fresh water. Our results will play an important role in the design of specific conservation strategies for fishery resources in this area. [ABSTRACT FROM AUTHOR]

Ecosystem-based management is costly. Therefore, without rigorously showing that it can outperform traditional species-focused alternatives, its broad-scale adoption in conservation is unlikely. We present a large-scale replicated and controlled set of whole-lake experiments in fish conservation (20 lakes monitored over 6 years with more than 150,000 fish sampled) to examine the outcomes of ecosystem-based habitat enhancement (coarse woody habitat addition and shallow littoral zone creation) versus a widespread, species-focused alternative that has long dominated fisheries management practice (i.e., fish stocking). Adding coarse woody habitats alone did not, on average, enhance fish abundance, but creating shallow water habitat consistently did, especially for juvenile fish. Species-focused fish stocking completely failed. We provide strong evidence questioning the performance of species-focused conservation actions in aquatic ecosystems and instead recommend ecosystem-based management of key habitats. [ABSTRACT FROM AUTHOR]

Coastal marine fisheries and the habitats that support them are under extensive and increasing pressures from numerous anthropogenic stressors that occur at multiple spatial and temporal scales and often intersect in unexpected ways. Frequently, the scales at which these fisheries are managed do not match the scales of the stressors, much less the geographic scale of species biology. In general, fishery management is ill prepared to address these stressors, as underscored by the continuing lack of integration of fisheries and habitat management. However, research of these fisheries is increasingly being conducted at spatial and temporal scales that incorporate biology and ecological connectivity of target species, with growing attention to the foundational role of habitat. These efforts are also increasingly engaging stakeholders and rights holders in research, education, and conservation. This multi-method approach is essential for addressing pressing conservation challenges that are common to flats ecosystems. Flats fisheries occur in the shallow, coastal habitat mosaic that supports fish species that are accessible to and desirable to target by recreational fishers. Because these species rely upon coastal habitats, the anthropogenic stressors can be especially intense—habitat alteration (loss and degradation) and water quality declines are being exacerbated by climate change and increasing direct human impacts (e.g., fishing effort, boat traffic, depredation, pollution). The connections necessary for effective flats conservation are of many modes and include ontogenetic habitat connectivity; connections between stressors and impacts to fishes; connections between research and management, such as research informing spawning area protections; and engagement of stakeholders and rights holders in research, education, and management. The articles included in this Special Issue build upon a growing literature that is filling knowledge gaps for flats fishes and their habitats and increasingly providing the evidence to inform resource management. Indeed, numerous articles in this issue propose or summarize direct application of research findings to management with a focus on current and future conservation challenges. As with many other fisheries, a revised approach to management and conservation is needed in the Anthropocene. [ABSTRACT FROM AUTHOR]

Determining the appropriate measurement scale to assess habitat variables is critical for ecologists assessing biological or ecological conditions. Depth, velocity, substrate, woody debris and other fish cover variables occur on both reach and microhabitat scales, and fish habitat associations with these variables may be scale‐dependent. The aim of this work was to better understand the importance of scale for fish–habitat associations with these variables in a framework consistent with environmental filtering and to test the hypothesis that habitat variable importance is scale‐dependent.I used prepositioned areal electrofishing in wadeable streams of the Delaware River basin to evaluate the associations of fish with the same variables summarised on different reach and microhabitat scales. The importance of scale for fish–habitat associations was assessed using two approaches that approximate an environmental filtering framework: variance partitioning with (1) ordination and (2) generalised linear mixed models.Variables on both the reach and microhabitat scales explained a significant fraction of the total variation in fish community composition (p < 0.05). Variation decomposition of reach‐ and microhabitat‐scale effects revealed 20.2% and 2.0% of all variation were due uniquely to reach and microhabitat scales, respectively. Measures of coarseness, embeddedness, amount of riffle and areal coverage of five fish cover variables were significant explanatory variables of community composition at the reach scale only (p < 0.05). Velocity and mesohabitat (amount or presence of riffle) were the only two habitat features that were significant explanatory variables of fish community composition at both the reach and microhabitat scales (p < 0.05). Individual models of species occurrence revealed similar patterns as seen with analyses of community composition.For many fishes, habitat features quantified at the reach scale were more explanatory than at the microhabitat scale. Longnose dace (Rhinichthys cataractae) were more dependent upon microhabitat variables than reach‐scale variables, relative to other fishes. Mean velocity at the reach scale was the most important explanatory variable for explaining fish community composition and indicated support for the concept of environmental filtering at the reach and microhabitat scales.Few studies of fish occurrence have incorporated a study design and analytical framework that approximates the hierarchical nature of habitat. This study identifies important scales and predictors, demonstrates the importance of a multiscale approach, and provides support for the environmental filtering concept at the reach and microhabitat scales. These findings will allow ecologists to better account for scale‐dependent habitat associations and justify the use of fish habitat associations on reach and microhabitat scales for assessing biotic integrity, restoration and conservation of fishes. [ABSTRACT FROM AUTHOR]

The Fish and Fish Habitat Protection Program (FFHPP) in Ontario and Prairie Region has requested science advice on approaches that can be used to define classification schemes and associated thresholds for reporting on the State of Fish and Fish Habitat (SOFFH) in the Lower Great Lakes and East Slopes of Alberta reporting areas. Science advice for quantifying and assessing the SOFFH in these reporting areas was also requested. This document describes approaches that can be used to develop classification schemes, including schemes based on (i) functional relationships with management objectives, (ii) established thresholds, (iii) relative ranking and (iv) expert elicitation. A decision tree for selecting among the approaches, based on the availability of different types of information, is presented. In addition, we consider how information from multiple Metrics can be synthesized to report on the status of overarching Indicators, as well as how classification schemes can be established for the quality of data used in SOFFH reporting. Finally, key uncertainties related to the development of classifications schemes, are also discussed. [ABSTRACT FROM AUTHOR]

The aim of this study is to assess the population dynamics of medaka fish (Oryzias nigrimas) in Lake Poso. Three habitats of this fish were surveyed, including Watudilana waters, Tolambo village waters and Taipa village waters. Samples were collected at night using a petromax lamp to attract fish. The fishing gear used nets of 8 by 3 meters with a mesh size of 3 by 3 millimeters. A total of 685 individuals of medaka fish (Oryzias nigrimas) were used for population dynamics analysis. Standard length was used to compare the current size of the endemic medaka fish Oryzias nigrimas with its size 28 years ago, while total length was used to examine data on growth, mortality, exploitation rate, recruitment yield and potential reproductive ratio. The male to female sex ratio of this type of fish fluctuated each month, where females tended to be more abundant than males. The average length of this fish is smaller than the standard length in 1993. However, its average size is larger than the freshwater medaka species Oryzias asinua, Oryzias wolasi and Oryzias woworae from Southeast Sulawesi and Oryzias matanensis from Lake Sulaw Towuti. The mortality rate of the medaka fish Oryzias nigrimas is mainly caused by the presence of introduced species and overexploitation. Selectivity of fishing gear, especially by catching fish measuring more than 50.70 millimeters, is strongly recommended for the conservation effort of this fish species. [ABSTRACT FROM AUTHOR]

Seagrasses worldwide provide key habitats for fish assemblages. Biogeographical disparities in ocean climate conditions and seasonal regimes are well-known drivers of the spatial and temporal variation in seagrass structure, with potential effects on associated fish assemblages. Whether taxonomically disparate fish assemblages support a similar range of ecological functions remains poorly tested in seagrass ecosystems. In this study, we examined variation in the abundance, diversity (from a taxonomic and functional perspective), and assemblage structure of fish community inhabiting nine meadows of the seagrass Cymodocea nodosa across three regions in the Mediterranean (Mallorca and Alicante) and the adjacent Atlantic (Gran Canaria), and identified which attributes typifying the structure of meadows, and large-scale variability in ocean climate, contributed most to explaining such ecological variation. Despite a similar total number of species between Mallorca and Gran Canaria, the latter region had more taxonomically and functionally diverse fish assemblages relative to the western Mediterranean regions, which translated into differences in multivariate assemblage structure. While variation in the abundance of the most conspicuous fish species was largely explained by variation in seagrass structural descriptors, most variation in diversity was accounted for by a descriptor of ocean climate (mean seasonal SST), operating at regional scales. Variation in fish assemblage structure was, to a lesser extent, also explained by local variability in seagrass structure. Beyond climatic drivers, our results suggest that lower temporal variability in the canopy structure of C. nodosa meadows in Gran Canaria provides a more consistent source of food and protection for associated fish assemblages, which likely enhances the more abundant and diverse fish assemblages there. [ABSTRACT FROM AUTHOR]

Microchemical maps, also known as "chemoscapes", hold immense potential for reconstructing fish habitat utilization and guiding conservation efforts. This approach relies on matching the microchemical composition of fish calcified structures (e.g., otoliths) with the surrounding water's microchemistry. However, applying this method faces a major challenge: a clear understanding of the spatiotemporal variability and drivers of water microchemistry, particularly in vast, free-flowing river ecosystems like the Nu-Salween River, Southeast Asia's longest free-flowing river. We analyzed the spatiotemporal variability and influencing factors of water microchemistry (i.e., Na:Ca, Mg:Ca, Mn:Ca, Cu:Ca, Zn:Ca, Se:Ca, Sr:Ca, and Ba:Ca) in the upper Nu-Salween River, based on a two-year sampling. Five elemental ratios (excluding Na:Ca, Mg:Ca, and Zn:Ca) in water demonstrated significant spatiotemporal variability, with Cu:Ca having the largest spatial variation, and Mn:Ca and Sr:Ca showing the greatest temporal variation. More specifically, four elemental ratios (Cu:Ca, Se:Ca, Sr:Ca, and Ba:Ca), exhibited significant variations along the longitudinal gradient, and Mn:Ca, Cu:Ca, Sr:Ca, and Ba:Ca, showed significant differences between mainstreams and tributaries. Temporally, Mn:Ca, Cu:Ca, and Ba:Ca displayed higher values and variations during the wet season, opposing the seasonal patterns of Na:Ca, Mg:Ca, and Sr:Ca. The four-element (Ba:Ca, Sr:Ca, Mg:Ca, and Mn:Ca) forest model showed the highest classification accuracy of 93%. Linear mixed-effects models showed that spatial factors have the largest influence on the variances in water microchemistry (56.36 ± 28.64%). Our study highlights the feasibility and reliability of utilizing microchemistry to reconstruct fish habitat utilization, thereby unveiling promising avenues for a more accurate understanding of fish life history in large rivers characterized by high heterogeneity in water microchemistry. By proportionally accounting for contribution of different factors to water microchemistry variability and relating them to microchemical composition of fish calcified structures, key fish habitats (e.g., spawning grounds) and migratory routes can be more precisely identified and thus protected. [Display omitted] • Spatiotemporal variability of water microchemistry affects chemoscape utilization. • Spatiotemporal and environmental factors influenced Nujiang water microchemistry. • Spatial variability in water microchemistry was greater than temporal variability. • Multi-element combinations demonstrated high accuracy in classifying sample sites. • The Nujiang chemoscape is useful to reconstruct fish habitat utilization history. [ABSTRACT FROM AUTHOR]

Ecosystems are increasingly degraded, fragmented and lost because of human activities globally. These impacts cause changes in the distribution of biodiversity and key ecological functions, modifications to food webs and reductions in ecosystem condition and seascape connectivity. Understanding whether, and how, the spatial context (i.e. extent, position) and condition (i.e. structure and condition of patches, including habitat forming species) of ecosystems coalesce to support their function as animal habitats is critical for effective and cost efficient coastal management. These potential combined, or interactive, effects of spatial context and habitat condition on fish assemblages are, however, rarely quantified. We sampled fish assemblages from six different ecosystems (mangrove, seagrass, saltmarsh, log snag, rocky outcrop and unvegetated sediment) across 13 estuaries in eastern Australia and quantified the relative importance of spatial context and habitat condition variables for fish assemblage composition. Spatial context variables were consistently more important than habitat condition in structuring fish abundance and diversity. Sites that were closer to smaller vegetated habitats (i.e. mangrove and seagrass) and key seascape features (i.e. estuary mouth and intertidal flats) typically supported diverse fish assemblages in high abundance. While the composition of fish assemblages was primarily linked to spatial context variables, habitat condition variables that index food availability were also important for fish in mangroves, seagrass and rocky outcrops. Our results show that fish abundance and diversity are intimately linked to seascape connectivity and heterogeneity, and have important implications for conservation planning and fisheries management decisions in coastal ecosystems. We highlight the importance of quantifying the influence of the combined effects of habitat condition and spatial context for biodiversity across multiple ecosystems, and expect the outcomes to lead to more efficient and effective management planning. [ABSTRACT FROM AUTHOR]

The responses of habitat and fish communities to extreme hydrological and habitat disturbance in typhoon-prone mountain streams are not studied much. Such landscape–climate settings may provide a unique opportunity for fish to evolve without special habitat adaptation and involve different assembly rules compared to temperate regions. This study aimed to compare fish communities and habitat factors before and after the typhoon season and to test the influences of various aspects of habitat on fish assemblages between seasons. Fish and habitats were surveyed at 30 wadable stream sites in March and December 2010 in tropical southern Taiwan. Habitat variables differed between the pre-typhoon and post-typhoon seasons. Higher species richness and the total number of fish caught in the pre-typhoon season indicated fast recovery. Benthic fish were more vulnerable to typhoon disturbances than sub-benthic fish. Contrary to the original hypothesis, fish communities were more strongly related to physical habitats than water quality and riparian conditions. In addition, consistently high fish variance explained by habitat measures in the dry seasons indicated that environmental filtering predominated. Dominant fish species were related to main habitat gradients, characterized by low species richness but high beta-diversity. Our findings provide implications for fish conservation in typhoon-prone mountain streams. [ABSTRACT FROM AUTHOR]

One‐dimensional numerical simulations based on the actual braided‐channel geometry in the middle reaches of the Yarlung Tsangpo River can be used to calculate the characteristics of braided channels in terms of their branching conditions and hydraulic parameters. Numerical modeling in the study area showed that a higher number of branches at fish‐spawning grounds may provide more suitable habitats for local organisms to survive. During most of the year, the distributions of the flow velocity and water depth in the higher‐branching channels were significantly lower than those in the lower‐branching channels. The hydromorphological index of diversity (HMID) of higher‐branching channels was higher than that of lower‐branching channels during all water periods, which showed the higher habitat heterogeneity of higher‐branching channels. The Froude numbers of higher‐branching channels ranged from 0.1 to 0.3, and the stable flow regime partially explained why higher‐branching channels are important habitats for fish‐spawning and nurseries. The lower flow velocities and water depths in the higher‐branching channels may have met the hydraulic habitat conditions for the survival of juvenile fish. This article analyses the characteristics of the hydraulic parameters and the ecological significance of braided river channels and provides theoretical support for the protection of fish habitats in braided rivers. [ABSTRACT FROM AUTHOR]

The fishing cat Prionailurus viverrinus is a wetland specialist species endemic to South and Southeast Asia. Nepal represents the northern limit of its biogeographic range, but comprehensive information on fishing cat distribution in Nepal is lacking. To assess their distribution, we compiled fishing cat occurrence records (n = 154) from Nepal, available in published literature and unpublished data (2009–2020). Bioclimatic and environmental variables associated with their occurrence were used to predict the fishing cat habitat suitability using MaxEnt modeling. Fishing cat habitat suitability was associated with elevation (152–302 m), precipitation of the warmest quarter, i.e., April–June (668–1014 mm), precipitation of the driest month (4–7 mm), and land cover (forest/grassland and wetland). The model predicted an area of 4.4% (6679 km2) of Nepal as potential habitat for the fishing cat. About two‐thirds of the predicted potentially suitable habitat lies outside protected areas; however, a large part of the highly suitable habitat (67%) falls within protected areas. The predicted habitat suitability map serves as a reference for future investigation into fishing cat distribution as well as formulating and implementing effective conservation programs in Nepal. Fishing cat conservation initiatives should include habitats inside and outside the protected areas to ensure long‐term survival. We recommend conservation of wetland sites, surveys of fishing cats in the identified potential habitats, and studying their genetic connectivity and population status. [ABSTRACT FROM AUTHOR]

Timing windows refer to a mitigation measure that defines low-risk periods for harm to fish and fish habitat from works, undertaking and activities (WUAs). The Fisheries and Oceans Canada Fish and Fish Habitat Protection Program (FFHPP) has requested scientific advice on the use of timing windows. To address this request, this document is structured around three main objectives outlined in the terms of reference. First, a literature search was conducted, and found that there is a paucity of peer reviewed scientific research connected to timing windows, and that literature on timing windows is dominated by material on dredging activities. An in-depth treatment of rationale, effectiveness, and frameworks for timing windows is provided. Canadian timing window use, rationale, and considerations varies among provinces and territories, but spawning is often cited as the fish life process targeted for protection. Second, a conceptual model outlines a set of rationale and considerations for the creation or modification of timing windows focusing on (1) the timing and vulnerability of fish life processes, (2) the characteristics of WUAs and associated pressures, and (3) the characteristics of habitat and environmental conditions. Importantly, life processes vary in their vulnerability to WUAs, but characteristics such as well-defined and predictable timing were identified among the factors that make some more suitable to mitigation with timing windows than others. Further considerations for migration, spawning, feeding, natal, rearing and refuge use are also presented. Characteristics of WUA pressures, including timing and persistence, were also identified as key factors for timing windows to consider. The interaction of pressures with fish habitat will be influenced by characteristics of the habitat and the environmental context. Protecting habitat processes with timing windows will depend on the process predictability, the mechanisms that regulate the WUA pressure and the habitat process, and the degree of overlap and strength of the pressure during exposure. Finally, we present a three-tiered approach to evaluate the effectiveness of timing windows to reduce the risk of exposure of fish life or habitat processes, the effects of pressures on the exposed process, and risk at the population level. Studies at each tier can inform comparisons of how risk varies through time, which is a key consideration when choosing among timing window options. This document advances the state of knowledge on the use of timing windows and on evaluating their effectiveness. The information presented can be used by FFHPP in the development of a science-based timing window framework to guide their creation and modification, to aid practitioners to identify potential risks of WUAs outside of established windows, and to inform their adaptation to changing environmental conditions. [ABSTRACT FROM AUTHOR]

The Fish and Fish Habitat Protection Program (FFHPP) has requested science advice on the potential consequences and how to quantify impacts from works, undertakings or activities (WUAs), other than fishing, that cause the death of fish, and ways that the death of fish can be offset. To support this request, this document is organized into four main sections. First, the available metrics for quantifying impacts and offsets for fish mortality are reviewed. There are differences in the data requirements and equivalency objectives among metrics; total biomass lost is the recommended metric for most cases. Second, modelling approaches that could be used to evaluate the community or food web consequences of fish mortality are briefly reviewed. An example of simple community models is provided, demonstrating that the outcomes for fish communities from fish mortality events are likely to be more than the sum of single species responses. Third, an overview is provided of the considerations that should be included in management decisions about fish mortality, providing information on the components that could be included in a risk management framework for WUA-related residual mortality. An adaptation of a precautionary fisheries management framework is presented as an example of a risk management framework for decisions about fish mortality impacts and offsets. Finally, the literature on current practices for offsetting fish mortality events is reviewed. There is evidence that habitat creation, habitat restoration and enhancement, and biological and chemical manipulation can all provide approaches to offsetting fish mortality, but consideration of the specifics of the offset application and sufficient monitoring, including pre-impact assessment, are needed to effectively achieve an offset for fish mortality. [ABSTRACT FROM AUTHOR]

Integrated planning is a policy driven process to establish ecosystem, cultural, social, and economic objectives in line with a given policy. Integrated plans can provide the overarching framework for multi-jurisdictional engagement, the inclusion of community and stakeholder interests, the setting of ecological objectives informed by multi-sectoral interests, the compilation of information from different knowledge systems, and ecosystem-based and adaptive management. They are a valuable platform for incorporating cumulative effects in decision making because comprehensive assessments of cumulative effects require an understanding of the ecological impacts of human activities to inform the policies and legislation used to manage them. Integrated planning can be used to operationalize an adaptive management approach that includes monitoring the state of fish and fish habitat and compliance with regulatory actions. Synthesis of information about past and current works, undertakings, and activities (and activities not under the jurisdiction of Fisheries and Oceans Canada) within an integrated plan will position the Fish and Fish Habitat Protection Program (FFHPP) to determine the effectiveness of Departmental management and conservation strategies for fish and fish habitat and evaluate program performance. However, FFHPP will also require an integrated planning policy to establish goals for planning and the processes to implement integrated plans through regulatory decision making process regarding project proposals. The context and scope of such a policy will also help frame the science needed to inform the planning process, the monitoring activities, and the regular review of the performance of the framework, and individual integrated plans regionally. We provide and customize examples from integrated planning internationally. [ABSTRACT FROM AUTHOR]

The 2019 revisions to Canada's Fisheries Act (FA) introduced, for the first time, the legislative mandate within the Act to consider cumulative effects (CE) in decision-making. Under paragraph 34.1 (1)(d) the Minister shall consider "the cumulative effects of the carrying on of the work, undertaking or activity referred to in a recommendation or an exercise of power, in combination with other works, undertakings or activities that have been or are being carried on, on fish and fish habitat". Within Fisheries and Oceans Canada (DFO), the Fish and Fish Habitat Protection Program (FFHPP) is the lead authority responsible for undertaking these considerations when reviewing proposed works, undertakings or activities (WUA). FFHPP requested Science Advice on the process for considering CE in decision-making with specific reference to the risk assessment process undertaken in project review. The following are the objectives of this report: (1) Evaluate the relevant elements within the current risk approach to determine if sufficient information is gathered to inform the consideration of CE. This includes (a) identifying recommendations for additional elements to be included in the current risk approach to inform the consideration of CE, and (b) identifying the fundamental information needed on species and habitats in the region of a project when considering CE. (2) Provide advice on key characteristics required to determine how habitat sensitivity can be determined in the context of CE. Thus, we focused on outlining the information needed to consider CE within decision-making. First, we identified the information needed for CE considerations with respect to the spatio-temporal context of a WUA. This section outlines the information needed from a scientific approach, independently from that currently used by the FFHPP. It includes the information needed about the WUA, and the species and habitats within the region of the WUA. Second, using this list we explored the current risk approach used by the FFHPP and whether there are elements missing from it that would assist in ensuring the full suite of information is included for CE considerations. Finally, we identified important elements that require follow-up research and examination through subsequent Canadian Science Advice Secretariat processes. [ABSTRACT FROM AUTHOR]

The study was aimed to investigate the current status and threats of fisheries resources in the Kura River, Bangladesh. Monthly fish catch surveys were carried out from December 2015 to November 2016 in four catchment areas at Hasinarghat, Kandir-dor, Pulertol, and Barartok. In addition, questionnaire interviews and focus group discussions (FGD) were done to clarify perceptions about the Kura River fishery status. A total of 59 fish species from 22 families were documented and of which 27% were threatened. The values of diversity (H), richness (D), and evenness (J') were calculated at 3.599, 4.345, and 0.921 respectively. The highest catch volume was recorded 19800±7722.71 kg in November 2016 at the Kandirdor and the lowest 225±110.65 kg in March 2016 at the Barartok (p<0.05). The upstream blockage (man-made dam) in the Kura River was identified as the main cause of fish habitat change, decrease fish biodiversity, and production of this River. Therefore, the findings of this study exposed that the conservation of fish has become urgent. In this regard, the baseline scenario of the Kura River biodiversity and threats will help to make awareness to take necessary conservation strategy as well as the need for further in-depth study. [ABSTRACT FROM AUTHOR]

Tor thai mahseer fish (Tor tambroides Blkr) is an endangered species due to overfishing and their habitat destruction. Some rivers in the hilly area of Sumatra are their habitats and become a conservation area. This study aims to determine the status of the fish habitat, conservation program, analyzing local wisdom in conservation as well as an economic resource for the local community. Conducted by a survey method in the conservation area in Batang Haluan River, West Sumatra, Indonesia. Parameters measured included water quality, physical character of conservation areas and descriptions of local wisdom and the protected area management. The area was divided into; core zone, sustainable use zone and use zone. The zones were established in 1856 (core zone), gradually from 1925 to 1970 (sustainable use zone) and in 1925 (use zone). This conservation activity has been running well, involved religious scholars, traditional and community leaders and the local government. Harvesting of tor thai mahseer fish have become cultural and tourism events and have a positive impact to social, economic and environmental benefits. The conservation has become part of local wisdom, fostered the values of kinship, togetherness, the spirit of mutual cooperation and the establishment of friendly relationships. [ABSTRACT FROM AUTHOR]

Environmental mitigation has become a catch-all term for efforts to avoid, minimize or compensate for the adverse impacts of development. Through an analysis of the expensive and complex plan developed to mitigate the anticipated impacts of deepening Savannah Harbor, I develop an ecobiopolitical approach to mitigation. Environmental mitigation is triage, involving difficult choices about which entities are worthy of concern and, thus, candidates for intervention – and, by extension, which are not. It involves decisions about which among the chosen deserve strict protection and which merit looser forms of care. As these processes move to center stage in twenty-first-century governance and politics, it has become important to understand what kinds of environments mitigation generates. What survives? What dies? What flourishes? This article focuses on initiatives designed to maintain minimally suitable conditions for non-human life. Insomuch as the object of habitat mitigation is the animal milieu, rather than the body or population, it can be understood as a form of ecobiopolitics. By contrasting the projected fates of three fish in the post-mitigation ecology of the Savannah River, I argue that the ecobiopolitics of habitat mitigation can be conceptualized at four registers. The first, comparity, highlights the value-laden processes through which some entities become candidates for mitigation and others do not. The second, hierarchy, underscores how candidates for mitigation are ranked in ways that shape the interventions pursued. The third, nonfungibility, foregrounds how problems of commensuration are negotiated in mitigation practice. The fourth, overflow, emphasizes how mitigation aimed at one entity can lead to other ecological changes. [ABSTRACT FROM AUTHOR]

Because dams block migratory routes of potamodromous fish to their spawning areas, and energy generation changes natural flow seasonality, it is necessary to identify spawning areas and their conditions. This information will help in management decisions in the Magdalena River basin regarding the future hydropower development. We identified which characteristics of the tributaries to the Magdalena River are important for determining potamodromous fish spawning grounds, and we estimated the percentage of future loss of spawning areas because of dam development. Ichthyoplankton density is directly related to the floodplain area, and inversely related with channel slope. Low channel slopes offer adult fish a longer distance for their upstream migration and a longer time for embryo development during their drift downstream from the spawning areas to nursery habitats (floodplain lakes). These features could increase the migration distance of the adults, the time for initial embryo development, and, because of its relationship with nursery habitats access, the offspring survival. The potential loss of the actual spawning grounds in the river network was estimated to be nearly 70% because of new dams. Our findings will help to reduce conflicts between hydropower and ecological interests. [ABSTRACT FROM AUTHOR]

The Fisheries Act (Act), a long‐standing Act protecting fisheries in Canada, was changed in 2012 to redefine its central purpose to the management of fisheries in Canada. Along with this refocus were changes that appeared to reduce protections for habitat and all fish. After an outcry by scientists, Indigenous peoples, and environmental organizations, the Act was revised in 2019 to "restore lost protections" thought to have been lost in the 2012 changes. To a large degree most of the "lost protections" have been restored, while other portions of the 2012 Act have been maintained. Challenges remain under the amended Act in efficiently implementing development and conservation projects while achieving the newly clarified purpose of the Act—the conservation and protection of fish and fish habitat. [ABSTRACT FROM AUTHOR]

Habitat simulation approaches (e.g., PHABSIM) have been used to model instream flows in thousands of streams and rivers and remain the most widely implemented detailed instream flow methodology. However, recent studies suggest that conventional habitat simulation models incorporate assumptions that may systematically underestimate instream flow needs, particularly for drift‐feeding fish. These include: (i) systematic biases in velocity habitat suitability curves (HSCs) caused by territoriality where dominant individuals displace subordinate fish to lower velocity micro‐habitats at high densities, thereby inflating the fitness value of low velocities; (ii) habitat simulation models do not account for flow effects on prey flux to drift‐feeding fishes, which may decrease more rapidly with reduced flow than does available habitat; (iii) use of focal velocities to construct traditional HSCs, which systematically underestimates velocity preference within the broader foraging arena of a drift‐feeding fish, and (iv) inadvertent use of low‐velocity HSCs associated with daytime refuging behavior from predators that may underestimate the higher velocities necessary for crepuscular foraging. Collectively, these factors suggest that current and historic flow prescriptions using traditional habitat simulation methods may underestimate optimal rearing flows for salmonids and other drift‐feeding species by anywhere from 10 to 50%. This implies that traditional instream flow management may be failing to provide the intended level of protection for drift‐feeding fishes in multiple streams at landscape scales. We provide guidelines for identifying contexts where model predictions are likely to be biased and approaches for correcting them. [ABSTRACT FROM AUTHOR]

Canada's Fisheries Act provides essential protection for fish and their habitat. To manage thousands of projects a year, Fisheries and Oceans Canada implements a risk‐based framework requiring authorization and offsetting for the highest risk projects. Projects considered lower risk proceed via letters of advice. Following changes to the Act in 2012, there were concerns about transparency and cumulative effects of low‐risk projects. We used access to information requests to obtain documents and reviewed the department's 2012–2019 risk‐based framework. Projects reviewed in Manitoba in 2016 were examined and the amount of permanent alteration and destruction approved without authorization was quantified (23,881 and 6,768 m2, respectively). The risk‐based framework focused reviews and regulatory decisions on project‐by‐project effects, rather than cumulative risks from multiple projects. Harm from lower risk projects was not tracked or offset. New mechanisms are needed to manage such projects to achieve the conservation purpose of the Act. [ABSTRACT FROM AUTHOR]

The Magnuson–Stevens Fishery Conservation and Management Act mandates US fisheries minimize adverse effects of fishing on essential fish habitat (EFH). The Gulf of Maine (GoM) American lobster (Homarus americanus) fishery is the most valuable US fishery and can deploy more than three million traps annually. To date, the impact of this fishery on benthic EFH has not been addressed quantitatively. To evaluate the impact of the GoM lobster fishery on EFH, we incorporated lobster fishing effort into a model linking habitat susceptibility and recovery to area impacted by fishing gear: the Swept Area Seabed Impact model. Impact to EFH was localized along the coast and highest along midcoast Maine. Upwards of 13% of the benthos is in the process of recovery, but between 99.92% and 99.96% of initially affected habitat fully recovers. These estimates suggest that lobster fishing negligibly contributes to accumulation of EFH damage in the GoM due to the expansive area fished and the small footprint of each trap. Identifying areas of persistent impact is crucial in developing effective fisheries management for critical marine habitats. [ABSTRACT FROM AUTHOR]

Stream drying, especially in the western United States, is becoming more common as the climate warms and precipitation patterns become less predictable; consequently, fisheries managers need to prioritize conservation efforts where water (and fish) will persist in the future. Yellow Creek in the upper Bear River watershed (Utah and Wyoming) contains one of the largest remaining populations of Northern Leatherside Chub Lepidomeda copei, an imperiled fish. Lower reaches are drying during summer months, partly due to water withdrawals, thus reducing Northern Leatherside Chub populations and relegating the remaining fish to isolated pools until the water returns. This study used an unmanned aerial vehicle to capture high‐resolution and spatially explicit imagery over 19 km of Yellow Creek in a few weeks during late August when the water is the most limiting to the fish. Through imagery and subsequent GIS analysis, we identified 405 previously unknown potential refuge‐pool habitats for Northern Leatherside Chub and determined their location, size, and spatial distribution, thereby helping managers prioritize stream reaches for native fish conservation and restoration. While the cost of unmanned aerial vehicle flights was estimated to be 2.5 times that of on‐the‐ground surveys in 2016, unmanned aerial vehicle technology continues to become more cost effective and, unlike traditional surveys, provides high‐resolution and spatially referenced data. [ABSTRACT FROM AUTHOR]

Coastal habitats worldwide face various threats, including sea level rise and land conversion. Coastal habitat loss has important economic consequences, as many of these habitats provide valuable ecosystem services including flood protection, carbon sequestration, and nursery areas for commercially fished species. Quantifying the economic value of these ecosystem services helps target policies for coastal habitat restoration. Here, we demonstrate how to quantify the contribution made by coastal habitats to the revenue (e.g., ex‐vessel values) of commercially fished species by estimating a residency index. This residency index weights the relative importance of a habitat along a species' lifecycle by explicitly incorporating the target species' life histories and the estimated proportion of time the species spends in that habitat at different life stages. We demonstrate how this method can be used to estimate the value of saltmarsh to UK commercial fisheries landings. This analysis suggests that UK saltmarsh contributes annually between 15% and 17.5% of total UK commercial landings for European seabass (Dicentrarchus labrax), European plaice (Pleuronectes platessa), and Common sole (Solea solea). Our findings support an economic argument for saltmarsh protection and restoration. Furthermore, our approach provides a general framework that integrates demographic methods and economic analyses to assess the value of saltmarsh and other coastal habitats for fisheries worldwide. [ABSTRACT FROM AUTHOR]

Fisheries and Oceans Canada's Fish and Fish Habitat Protection Program (FFHPP) has a regulatory regime in place to avoid, mitigate and offset the negative effects of projects on fish and fish habitat. To understand these negative effects, Pathways of Effects (PoE) diagrams are used to describe linkages between the works, undertakings, and activities (WUAs), the 'pressures' by which WUAs affect the ecosystem, and the resulting 'endpoints' affecting fish and/or fish habitat. Twenty original PoE diagrams have been recently combined into four proposed diagrams focused on 1) land-based WUAs, 2) energy and noise producing WUAs, 3) in-water WUAs, and 4) WUAs affecting water flow. Here we provide a selective review of these four PoE diagrams to assess whether the pressures, pathways, and endpoints are valid, comprehensive, and complete. A range of support levels were found for pressure pathways, identifying well supported connections, those that have a theoretical basis but lack extensive research, those with potential alterations for improved comprehensiveness and accuracy, and those lacking support. Numerous recommendations are included for alterations to terminology and addition or removal of linkages and nodes. Related resources are included in a database that may serve to support the application and further development of additional PoE diagrams. It is challenging to encompass the wide variety of complex impacts that human activities may have on fish and fish habitat, and we recognize a trade-off between the comprehensiveness and tractability of these diagrams in communication and decision making. Consideration of this trade-off while integrating these recommendations is important to ensure maximum validity and applicability by FFHPP. To employ ecosystem-based management accounting for the cumulative effects of activities on ecosystem state, there is a need to further identify interconnectivity amongst these PoE diagrams, as well as how various pressure pathways interact to produce cumulative effects. [ABSTRACT FROM AUTHOR]

Small-scale fisheries are responsible for landing half of the world's fish catch, yet there are very sparse data on these fishing activities and associated fisheries production in time and space. Fisheries-dependent data underpin scientific guidance of management and conservation of fisheries systems, but it is inherently difficult to generate robust and comprehensive data for small-scale fisheries, particularly given their dispersed and diverse nature. In tackling this challenge, we use open source software components including the Shiny R package to build PeskAAS; an adaptable and scalable digital application that enables the collation, classification, analysis and visualisation of small-scale fisheries catch and effort data. We piloted and refined this system in Timor-Leste; a small island developing nation. The features that make PeskAAS fit for purpose are that it is: (i) fully open-source and free to use (ii) component-based, flexible and able to integrate vessel tracking data with catch records; (iii) able to perform spatial and temporal filtering of fishing productivity by fishing method and habitat; (iv) integrated with species-specific length-weight parameters from FishBase; (v) controlled through a click-button dashboard, that was co-designed with fisheries scientists and government managers, that enables easy to read data summaries and interpretation of context-specific fisheries data. With limited training and code adaptation, the PeskAAS workflow has been used as a framework on which to build and adapt systematic, standardised data collection for small-scale fisheries in other contexts. Automated analytics of these data can provide fishers, managers and researchers with insights into a fisher's experience of fishing efforts, fisheries status, catch rates, economic efficiency and geographic preferences and limits that can potentially guide management and livelihood investments. [ABSTRACT FROM AUTHOR]

Many marine species exhibit poleward migrations following climate change. The Barents Sea, a doorstep to the fast‐warming Arctic, is experiencing large scale changes in its environment and its communities. Tracking and anticipating changes for management and conservation purposes at the scale of the ecosystem necessitate quantitative knowledge on individual species distribution drivers. This paper aims at identifying the factors controlling demersal habitats in the Barents Sea, investigating for which species we can predict current and future habitats and inferring those most likely to respond to climate change. We used non‐linear quantile regressions (QGAM) to model the upper quantile of the biomass response of 33 fish species to 10 environmental gradients and revealed three environmental niche typologies. Four main predictors seem to be limiting species habitat: bottom and surface temperature, salinity, and depth. We highlighted three cases of present and future habitat predictability: (a) Habitats of widespread species are not likely to be limited by the existing conditions within the Barents Sea. (b) Habitats limited by a single factor are predictable and could shift if impacted by climate change. If the factor is depth, the habitat may stagnate or shrink if the environment becomes unsuitable. (c) Habitats limited by several factors are also predictable but need to be predicted from QGAM applied on projected environmental maps. These modeled suitable habitats can serve as input to species distribution forecasts and end‐to‐end models, and inform fisheries and conservation management. [ABSTRACT FROM AUTHOR]

Interspecies and intraspecies variation in the use of wooded habitats has been studied for salmonids, but little is known about nonsalmonid species. In this study, we explored spatiotemporal differences in the distribution of three cyprinid species at habitats of varying wood density and at habitats of varying heterogeneity in a Mediterranean intermittent river (Evrotas, southern Greece). Hydroecological data from 843 microhabitats across four sites and in five sampling periods were collected and analysed using generalized linear mixed effects models. Adult chubs, minnowroaches, and minnows and, to a lesser degree, juvenile chubs, preferred complex, wooded habitats, characterized by lower flow velocities, higher water depths, finer substrate, and increased canopy cover, compared with wood‐free and noncomplex habitats. At the advanced stage of the dry period, the deeper, wooded habitats served as drought refugia; all fish groups, except for the adult chub, resorted to these habitats during autumn. In contrast, no such shifts were evident in early summer at the onset of the dry period. In late spring, all fish groups had higher densities at wooded habitats, a shift probably associated with reproduction. Wood density did not affect fish habitat use, as fish densities were similar across wooded habitats. In contrast, habitat heterogeneity significantly affected fish densities; more adult chubs and minnows were observed in complex habitats, whereas juvenile chubs and minnowroaches clearly preferred less complex habitats. We conclude that the targeted maintenance of instream wood structures to ensure habitat heterogeneity is a key‐action for the successful conservation of riverine fish populations. [ABSTRACT FROM AUTHOR]

The western Mediterranean basin is a high marine biodiversity area under severe pressure by changing climate and intense human activities. Beyond national jurisdictions, international institutions such as the General Fisheries Commission for the Mediterranean (GFCM) work towards canalizing a regional consensus that fishing practices should evolve to better support the 2030 Agenda for Sustainable Development. In this context, Fisheries Restricted Areas (FRA) are proposed as effective management measures to contribute towards increasing fisheries sustainability in the region that can be considered, under some conditions, as Nature-based Solutions (NbS); however, how to operationalize their framework remains unclear. In this study, based on combined ecological and fisheries criteria, we identify and prioritize six potential priority areas for management (PAMs) in the western Mediterranean Sea. They are specifically aimed at the protection and recovery of Essential Fish Habitats and the conservation of Vulnerable Marine Ecosystems, whilst requiring limited adaptation of fisheries practices due to their relative low fishing pressure. We compare the identified areas to those that are currently under protection, and to areas that have been proposed for protection at the GFCM. Our results show that the FRAs and other spatial management measures introduced in the last years marginally contribute to the protection PAMs in the western Mediterranean region. However, the adoption of FRAs that are currently under discussion at the GFCM could contribute significantly to improve the situation. FRAs could also contribute to operationalize NbS in the western Mediterranean Sea when properly designed and implemented. • This study identifies six priority areas for management (PAMs) in the western Mediterranean Sea. • PAMs are based on combined ecological and fisheries criteria, with multiple ecological values and relative low trawling. • Current spatial management measures implemented have little contribution on PAMs protection. • Fisheries Restricted Areas discussed at the GFCM can significantly increase the protection level of high priority PAMs. [ABSTRACT FROM AUTHOR]

Anthropic exploitation of soil, forests, and water bodies contributes to the modification of river flow regimes and sediment transport dynamics, thus affecting fish habitats and water quality. In the last decades, the increasing awareness of the consequences of such modifications on natural contexts has stimulated researchers and practitioners to provide more innovative solutions aiming at enhancing river biodiversity. Recently developed eco-friendly approaches for river restoration evidenced the necessity of more careful planning and management of natural resources, including the maintenance and enhancement of fish species' habitats. The present study aims at assessing the interaction of different types of wood- and rock-made instream structures with river flow regimes and habitat requirements of many freshwater fish species, accounting for the influence of downstream scour potholes to facilitate fish species migration and spawning. Experimental tests showed that instream structures cause deep scour holes characterized by low flow velocity zones, thus decreasing the required fish swimming power and potentially providing suitable conditions for the migration of freshwater fish species. Using dimensional analysis, empirical relationships were derived to optimize the longitudinal distance between subsequent instream structures, accounting for the effects of various structure geometries and fish biological characteristics. Nevertheless, further investigation is needed to validate the proposed relationships at prototype scale. This study ultimately contributes at providing tools to design river instream structures favorable to fish migration. • The effects of different types of instream structures on fish swimming hydrodynamics have been investigated. • The analysis was conducted at model scale under identical fish Froude numbers F f. • Results showed that instream structures facilitate the migration of freshwater fish species. • Fish white muscles weight increases with the fish weight resulting in an increase of the available fish power. [ABSTRACT FROM AUTHOR]

Telemetry is an increasingly common tool for studying the ecology of wild fish, with great potential to provide valuable information for management and conservation. For researchers to conduct a robust telemetry study, many essential considerations exist related to selecting the appropriate tag type, fish capture and tagging methods, tracking protocol, data processing and analyses, and interpretation of findings. For telemetry-derived knowledge to be relevant to managers and policy makers, the research approach must consider management information needs for decision-making, while end users require an understanding of telemetry technology (capabilities and limitations), its application to fisheries research and monitoring (study design), and proper interpretation of results and conclusions (considering the potential for biases and proper recognition of associated uncertainties). To help bridge this gap, we provide a set of considerations and a checklist for researchers to guide them in conducting reliable and management-relevant telemetry studies, and for managers to evaluate the reliability and relevance of telemetry studies so as to better integrate findings into management plans. These considerations include implicit assumptions, technical limitations, ethical and biological realities, analytical merits, and the relevance of study findings to decision-making processes. [ABSTRACT FROM AUTHOR]

The specificity and accuracy of inferred fish origin and movement relies on describing spatial heterogeneity and temporal stability of environmental signatures. But the cost and logistics of sample collection often precludes the complete quantification of environmental signature temporal stability and spatial heterogeneity. We used repeated sampling and a novel approach (Bayesian ridge regression, BRR) to quantify the temporal stability and spatial heterogeneity of 87Sr/86Sr, respectively. We explained 86% of observed variation in 87Sr/86Sr using a BRR model and estimated 87Sr/86Sr throughout the Upper North Platte River Basin with high accuracy (±0.00106). Year to year variation in 87Sr/86Sr signatures ranged from 0.00007 to 0.00073 (SD), while seasonal variation ranged from 0.00091 to 0.00134 (SD). We then assessed the specificity and discussed the accuracy of inferring movement using three scenarios of described spatial heterogeneity. Our results indicate reliable inference of fish movement requires comprehensive quantification of spatial heterogeneity and temporal variation in environmental signatures. [ABSTRACT FROM AUTHOR]

More than half of the diminutive North American catfish species known as madtoms (Noturus spp.) are considered imperiled due to range reductions from habitat fragmentation and degradation. In response, government agencies regularly conduct sampling that targets these cryptic fishes. Unfortunately, the effectiveness and biases associated with common sampling gears has rarely been quantified for non‐game fish, including madtoms. To improve sampling protocols for diverse madtom species, we: (a) quantified the detection probabilities and effort necessary to detect five species of madtom with relative certainty using complimentary sampling gears, and (b) described biases associated with size‐selectivity of the same gears when used to sample madtoms. Five madtom species that are native to Mississippi streams and have two distinct coloration patterns were selected: uniform pattern, Brown Madtom (Noturus phaeus) and Freckled Madtom (Noturus nocturnus); patterned, Piebald Madtom (Noturus gladiator), Least Madtom (Noturus hildebrandi), and Brindled Madtom (Noturus miurus). These species were captured using four standardized sampling gears (i.e., backpack electrofisher, seine, dipnet, and Gee‐style minnow trap) from 13 isolated stream reaches in Mississippi during baseflow conditions between August and November 2016. Each gear was randomly assigned to up to five transects at each site resulting in a maximum of 20 unique samples per stream reach. We estimated the detection probability of each species with each gear using presence–absence capture data. Cumulative detection probabilities were calculated for each species and gear combination to describe the number of samples necessary to achieve a detection probability of 0.95. Additionally, we pooled all capture data across sampling sites to compare madtom size distributions among gears. Electrofishing was generally the most efficient gear for detecting madtoms, but slightly overestimated fish size distributions. By seining, managers can expect to capture all species evaluated with a modest amount of effort; however, are likely to catch relatively small individuals. Seining was the most effective gear for only Piebald Madtom, a species petitioned for listing under the Endangered Species Act. To be relatively certain that Piebald Madtom are absent from a stream reach would require sampling ten 100 m transects by seining. In contrast, the same certainty would require more than twenty 100 m electrofishing transects. Minnow traps and dipnetting generally performed poorly and failed to detect some species at occupied sites. Biologists can now consider using each of these complimentary gears assessed when evaluating species status and population structure for diverse madtom species, while explicitly acknowledging the biases associated with each gear. [ABSTRACT FROM AUTHOR]

Many diadromous fish populations are declining and at risk of collapse. Lack of river connectivity is a major contributor to these declines, as free migration routes between marine and freshwater habitats are crucial for life‐history completion. For the conservation and ultimately recovery of such species, it is imperative that remedial measures aimed at increasing connectivity are effective.This study investigated the distribution patterns of ascending juvenile European eel (Anguilla anguilla L.) in rivers in south‐western Sweden, with a focus on the effects of barriers and measures that aim to reduce the impact of barriers, i.e. fish‐passage solutions (FPSs).Eel occurrence data were spatially and temporally integrated with the national databases of dams and FPSs in a Geographic Information System (GIS) environment to evaluate their effect on ascending eel distribution. The types of barriers assessed were: (i) dams with nature‐like fishways; (ii) dams with eel ramps; (iii) dams with technical fishways; and (iv) dams without FPSs.Dams fitted with eel ramps or technical fishways, as well as dams without FPSs, produced a significant negative effect on the probability of eel occurrence upstream. This negative effect was not found for dams fitted with nature‐like fishways, indicating that these solutions may function better than the other FPS types in this study. The probability of eel occurrence decreased with distance from the sea and increased with area sampled, number of electrofishing runs, water temperature, and with the size of the bottom substrate.We suggest that future conservation strategies for improving the natural immigration of juvenile eels should include optimizing FPS function (e.g. placement and design), the continued maintenance of FPSs, the construction of nature‐like fishways, and preferably the removal of dams, which will also benefit the downstream migration of maturing eels as well as restoring other ecosystem services. [ABSTRACT FROM AUTHOR]