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Ethiopia has considerable freshwater potential. Currently, the recognized fish diversity in the country's freshwater ecosystem is more than 200. Despite the presence of such high fish diversity with considerable economic returns, ichthyofaunal studies on Ethiopian rivers are scarce. Thus, this study aimed to identify and compare ichthyofaunal diversity and distribution in floodplain rivers of the Abbay and Tekeze Basins, Ethiopia. Fish were collected using gillnets, cast nets, hooks, electrofishing, and mosquito nets and identified to the species level. Gillnets had stretched mesh sizes of 4–14 cm with a panel length of 25–75 m and a width of 1.5–2 m per mesh size. They were set in the afternoon (5:00 p.m.) and lifted the following morning (7:30 a.m.). Immediately after capture, fish were preliminary identified in the field and tagged with proper information (e.g., sampling locality and date of collection). Similar fishing efforts were applied at all sampling sites for two dry and two wet months over a period of two years (2018-2019). In the present study, both alpha and beta diversity indices were also examined. Identification keys and an annotated checklist of species were generated for easy naming of the entire fish species in the basins. In the ichthyological collection, 43 fish species with 11 new records from the Ayima, Gelegu, and Shinfa Rivers were identified. The first two rivers in the Abbay Basin were the richest in species and number of individuals. Gelegu River had the highest abundance as well. Generally, this study was conducted in areas where no fish biodiversity studies have been undertaken, and the results obtained from this study could be important for fish biodiversity conservation. [ABSTRACT FROM AUTHOR]

Length-weight relationships are presented for twelve fish species collected at 22 sampling points in the Heishui River, a priority tributary for fish conservation in the mainstream of the Baihetan Reservoir area, China. A combination of gill nets was used for sampling over a period between November 2018 and May 2021. The gill nets consisted of 12 nets per point with dimensions of 20 × 2 m (length and width), mesh size ranging from 20 to 80 mm, and soaking depth ranging from 40 to 160 cm. In addition, fixed gill nets were employed, with 10 nets per point having dimensions of 10 to 30 m in length and 1.5 to 2.5 m in width. The mesh size of these fixed gill nets was 10, 15, or 20 mm. This study presents the length-weight relationships of twelve species for the first time in the Heishui River Basin, including the new maximum body length of Pseudorasbora parva (Temminck and Schlegel, 1846). The slope (b) values for the assessed species ranged from 2.5 to 3.5. All the estimated relationships are highly significant (P < 0.05) with a high coefficient of determination R 2 ranging from 0.9574 to 0.9997. It is expected that the results obtained from this study will contribute to filling the knowledge gap in this area and also assist fisheries scientists in future assessment studies. [ABSTRACT FROM AUTHOR]

Length-weight relationships (LWRs) were described for four fish species inhabiting the tributaries of the Dongting Lake, China. Fish were sampled using stationary gillnets (50 m long × 2.0 m high and mesh size: 2, 6, 10, and 14 cm) and lobster pots (18 m long × 0.33 m high × 0.45 m width and mesh size: 1 cm) twice a year from May 2021 to July 2023. All fishes were measured in the field immediately after collection for total length (L) to the nearest 0.1 cm and body weight (W) to the nearest 0.1 g. There was a strong correlation between total length and weight in all four species (r2 > 0.98). The values of parameter b in LWR ranged from 2.9709 to 3.4373. The LWR of Sinilabeo tungting, Acrossocheilus jishouensis, Onychostoma rara, and Onychostoma barbata provide new data for https://Fishbase.org and can be useful for establishing conservation measures of fish resources after fishing closure in the Dongting Lake basin, China. [ABSTRACT FROM AUTHOR]

Length‐length (LLRs) and length‐weight relationships (LWRs) were described for ten fish species inhabiting the Yichang reach in middle Yangtze River below Gezhouba Dam, China. Fish were sampled using drifting gillnets (30–40 m long ×1.0–1.5 m high, mesh size: 20, 40 and 60 mm) and stationary gillnets (40–60 m long ×1.8–2.0 m high, mesh size: 20, 40, 60, 80, 100 and 140 mm) from October to next January each year between October 2016 and January 2021. All fishes were measured in the field immediately after collection for total length (TL) and standard length (SL) to the nearest 0.1 cm and for body weight (BW) to the nearest 0.1 g. There was strong correlation between length and weight of all ten species (r2 > 0.95). The values of parameter b in LWRs ranged from 2.871 to 3.480. The results provided new data for FishBase and for establishing conservation measures of fish resources after fishing closure in the Yangtze River. [ABSTRACT FROM AUTHOR]

Energetic stores can be metrics of fish health but are determined using lethal methods. Validation of non‐lethal alternatives to estimate energetic stores would facilitate monitoring of wild fish of conservation concern, such as sturgeons. The Distell Fatmeter, a microwave energy meter, has been validated to estimate energetic reserves in a range of fish taxa but has not been tested on sturgeon. Therefore, Fatmeter measurements were tested as a predictor of captive hatchery‐origin juvenile pallid sturgeon (fork length: 240–415 mm) energetic reserves determined by lethal proximate analysis. Fatmeter measurements combined with size and condition metrics accounted for 40 to 45% of the variation in whole‐body energetic reserves, which is notably lower than reported in previous studies on other fish taxa and a modest improvement on variation explained by size and condition metrics alone in the same sturgeon population. We suggest the low variation accounted for by the Fatmeter may be a result of small body size and low whole‐body lipid content and recommend follow‐up studies on sturgeon larger than 415 mm in fork length. [ABSTRACT FROM AUTHOR]

The present study describes new estimates of length‐weight relationships (LWRs) for 14 indigenous fish species collected from the Narmada River. Fish specimens were collected weekly using gill nets (30.0 m long, 3.0 m high, and mesh size 12.5–127.0 mm) between October 2021 and March 2022. Total length (TL) and weight for each specimen were measured to the nearest 0.1 cm and 0.1 gm, respectively. This study provides first species‐specific LWRs for four species (Tor tor, Rasbora daniconius, Rita gogra and Clarias magur), new maximum TL for seven species (Notopterus notopterus, Labeo bata, Systomus sarana, Crossocheilus latius, Xenentodon cancila, Channa marulius and Mastacembelus armatus), and new and wider size range for three species (Chitala chitala, Tenualosa toli and Labeo boggut). Findings of this study have implications in the management and conservation of the species‐specific fisheries resources within the geographical range. [ABSTRACT FROM AUTHOR]

This work describes the length‐weight relationship (LWR) of ten fish species from the Contas River Basin, Bahia State, Brazil. Sampling was conducted quarterly between November 2012 and November 2013 in 18 wadeable streams (nine in the Diamantina Plateau, Caatinga biome, and nine in the Atlantic forest biome). The fishes were caught using electrofishing (800V DC) and hand nets (2.0 mm mesh size) in 50 meters stretch by the sample unit. Collected fishes were fixed in formalin and preserved in alcohol, and thus some shrinking probably occurred. The values of parameter b of the LWR (W = aLb) ranged between 2.763 and 3.267. It is the first record of LWR parameters for nine species, all endemic to Northeastern Mata Atlântica freshwater ecoregion (NMAF). Moreover, new maximum lengths are presented for five species. [ABSTRACT FROM AUTHOR]

Genus Chirostoma belongs to Atherinopsidae family and it is an endemic species from the Mesa Central in Mexico. Abundance of its species have decreased and some ones have been placed on the threatened species list, because of overfishing, urbanization, industrialization, destruction, habitat fragmentation, pollution and exotic species introduction. Chirostoma jordani (Woolman, 1894) is a freshwater fish with biological, ecological, cultural, and commercial importance. It has a broad distribution in Lerma drainage, Durango and Mexico City. In this last locality, their populations, although small, still persist in Xochimilco Lake; it is necessary to implement biotechnologies for their conservation, because of these causes and their basic biology. The aim was to standardize a sperm cryopreservation protocol in C. jordani, to determine extender solution, cryoprotective agent type and concentration, equilibrium time, freezing and thawed rate to be applied in assisted reproduction and conservation of genus Chirostoma. Chirostoma jordani adult males were collected in Atlangatepec Dam, Tlaxcala State, Mexico, to fresh seminal evaluation and cryopreservation protocol standardization. Four cryoprotectants effect was evaluated: dimethylsulfoxide (DMSO), methanol (MeOH), ethylene glycol (EG), and glycerol (GL) at five concentrations: 2%, 6%, 10%, 14% and 16% v/v. Higher and lower DMSO and MeOH 10% and EG 14%, decreased post‐thaw motility percentage. Both DMSO and MeOH 10% and EG 14% had the highest post‐thaw motility percentages, 48.8 ± 1.5%, 54.5 ± 1.0% and 53.5 ± 1.0%, at 15, 10, and 5 min equilibrium times, respectively, thawed at 40°C. Chirostoma jordani sperm can be cryopreserved with both DMSO and MeOH 10%, and EG 14%. These ones can be used for assisted reproduction. GL was not efficient, since it presented a post‐thaw motility percentage very low. [ABSTRACT FROM AUTHOR]

Seamount fish communities are susceptible to variations due to the oceanographic conditions and level of historical fishing effort. In the NE Atlantic, the Azores is considered an "oceanic seamount ecosystem area" because seamount concentration is high relative to other regions. Scientific information on seamounts in the Azores remains scarce and demersal fishery occurs mostly without any knowledge to endorse sustainable harvest strategies. To make available an important baseline information on dynamics of demersal fish populations inhabiting commercially exploited seamounts, the present study has as specific objectives to (a) describe the taxonomic composition of demersal fish assemblages on underwater mountains, (b) examine whether assemblages vary spatial and temporally, and (c) investigate what drives distributional patterns of species in terms of abundance and size composition. For this, three Azorean seamounts (Açores, Princesa Alice and Mar da Prata) exploited by bottom fishing were selected as case study areas. Data were obtained from scientific surveys and commercial fishery over the past c. 25 years. A total of 84 species from 45 families were identified. Sebastidae, Moridae, Sparidae and Centrophoridae were the most abundant families, mainly represented by Helicolenus dactylopterus, Mora moro, Pagellus bogaraveo and Deania profundorum, respectively. Fish assemblages were more distinguishable spatially than temporally. Depth was identified as the main factor responsible for these differences. The higher occurrence of shallow and intermediate (i.e., up to 600 m) habitats in Princesa Alice and Açores seems to favor the occurrence of a greater number of species and higher abundances in comparison to Mar da Prata. Phycis phycis, Pontinus kuhlii, H. dactylopterus, P. bogaraveo, Conger conger and M. moro were the species which primarily contributed to dissimilarities in assemblage structure among sample groups. Abundance indices and fish sizes showed a decreasing trend for many of these species, especially for those with sedentary behaviour inhabiting historically highly exploited seamount areas. These results highlighted the vulnerability of demersal fishes to the expansion of fishing effort in the offshore seamount areas. Spatial management of seamounts should be a priority being fish conservation balanced with strategies that support sustainable fisheries. [ABSTRACT FROM AUTHOR]

Knowledge of fecundity in fishes is important for understanding life history, modeling population dynamics, developing fisheries management and determining conservation status. Sturgeon species are known for their high fecundity but to date only two populations of Atlantic sturgeon (Acipenser oxyrinchus Mitchill, 1815) have been examined for this aspect of their biology. The species is protected in most regions of eastern North America but the Saint John River, New Brunswick supports one of the two remaining commercial fisheries in Canada. Sixty females selected by this fishery were sampled for total length, weight, age, gonad weight and egg number. Absolute fecundity ranged from 153,630 to 1,306,626 eggs, with a mean fecundity of 582,832 ± 261,806 eggs. Absolute fecundity exhibited a significant positive relationship to increasing body weight but not to total length or age. Relative fecundity ranged from 129 to 216 eggs/g gonad weight and although it declined with both increasing body size and age the relationships were not significant. The Gonadosomatic Index (GSI) ranged from 1.3% to 27.0% with a mean of 7.8% ± 4.94 SD. Relative fecundity found in this study was higher and mean GSI lower than reported for other Atlantic sturgeon populations and other sturgeon species. Differences were probably due to location of the fishery downstream from spawning sites and selection of pre‐spawning females by the commercial fishery. [ABSTRACT FROM AUTHOR]

The marbled rockfish (Sebastiscus marmoratus) is an important species that is widely distributed across the marginal seas of the northwestern Pacific. Several kinds of DNA markers, such as amplified fragment length polymorphisms (AFLP), mitochondrial DNA (mtDNA) and single nucleotide polymorphisms (SNPs), have been used to assess the population genetic characteristics of this species in previous studies. However, there have been no genetic profiling studies to cover the entire distribution. Here, six highly polymorphic microsatellite markers were applied to 18 populations across a spatially large area (from the Sea of Japan in the north to the South China Sea in the south). The results showed that the whole population exhibits high, stable genetic diversity, low relatedness and large effective population size. There was very weak genetic differentiation overall and no isolation by distance occurred among the populations, which may be attributed to significant contemporary gene flow, each generation. The above results may lead us to infer that the recent S. marmoratus population structure could be considered as one large integrated population. The present study will be beneficial to population conservation and fisheries management of S. marmoratus and will lead to better insights into the genetic characteristics of other species that belong to the Sebastidae family. [ABSTRACT FROM AUTHOR]

The Pearl River Estuary is the largest estuary in South China and plays a considerable role in the local fisheries economy, yet little is known about the current state of fish assemblage in this ecosystem. To quantify spatial‐seasonal variations, environmental influences, and trends over the past three decades of the fish assemblage in the Pearl River Estuary, we sampled 11 sites seasonally from December 2013 to September 2016. Throughout the study, 285 species from 88 families and 195 genera were collected. There were obvious spatial and seasonal variations of the fish assemblage in terms of the dominant species, species richness, and composition of ecological types. Mouth distance, NH4+ N, chlorophyll‐a, flow, DO, salinity and water transparency were the main variables influencing the spatial‐temporal dynamic of fishes within the estuarine systems. Compared with the record of 330 species in the 1980s, the number of fish species in the Pearl River Estuary has declined by 45 fish species. The Jaccard's similarity of fish composition between the historical investigation (the 1980's) and the present investigation (2013–2016) was 0.62, with 95 species undiscovered and 50 species increased in the present study compared to the 1980s, indicating the assemblage structure has obviously changed. However, in term of ecological guilds, there was no significant difference in the composition of all the selected ecological traits between these two periods. Anthropogenic activities including overfishing, introducing alien fish, dam construction and pollution were considered the main disturbance on fish composition over the past three decades. We conclude that there existed pronounced spatiotemporal changes of fish assemblages, which arises from the compounding effects of environmental factors and anthropogenic activities. These findings are beneficial to understanding and developing suitable conservation strategies for the management and protection of fish resources in the Pearl River Estuary. [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]

Shovelnose sturgeon (Scaphirhynchus platorynchus, Rafinesque, 1820) in the Wabash River, Illinois/Indiana, USA, provide an important recreational sport and commercial caviar fishery. In fact, it is one of the last commercially viable populations for sturgeon roe harvest. Due to increased demand in the caviar trade and endangered species legislation that protect shovelnose sturgeon in only a portion of their range, efforts of the roe harvest market may continue to divert toward unprotected populations like the shovelnose sturgeon in the Wabash River. Previous studies have shown that increased harvest pressure in this species can affect the age‐at‐maturation and result in recruitment overfishing. Therefore, it is important to closely and continuously monitor commercially exploited populations. Over the past decade (2007–2016), 13,170 shovelnose sturgeon were sampled with boat electroshocking, hoop nets, drift nets, trotlines, and benthic electrified trawls. Captured fish ranged from 61 to 910 mm fork length (FL; mean = 668 mm), with very few fish less than 550 mm FL. Although fish were found to be in a healthy condition (mean relative weight = 87), there was a decrease in the mean condition over time. In addition, we saw declines in mean FL, weight of roe‐per‐fish, and size‐at‐maturity for female fish directly impacted by harvest. The decline of these population parameters, coupled with an increase in total annual mortality and a truncated age frequency distribution, suggest that harvest is negatively impacting the demographics and recruitment of shovelnose sturgeon in the Wabash River. Considering the downward trajectory of population dynamics and high estimates of mortality, their resiliency to continued harvest and environmental changes will be limited. [ABSTRACT FROM AUTHOR]

The length‐weight relationships (LWR) were estimated for five fish species from the Golfão Maranhense, Brazilian Amazon littoral region. Samplings were performed in August 2016, during the dry season, using trawl net with 6.0 m length by 3.0 m width (trawl mouth opening of 6.0 m2) and 1.0 cm mesh size between opposite knots. This study registers LWR for Anchoviella elongata and Gobioides broussonnetii and the estimated LWR for Aspredo aspredo and Aspredinichthys filamentosus covers a wider size range. Moreover, it is presented maximum length values for A. elongata and Sphoeroides greeleyi. [ABSTRACT FROM AUTHOR]

Summary: The Mary River cod (Maccullochella mariensis) is a large predatory freshwater fish identified as a potential flagship for freshwater ecosystem conservation in Australia. The species is endemic to the Mary River catchment in eastern Australia, and is listed as Endangered. Previous conservation genetic assessment of Mary River cod was based on a small set of microsatellite loci developed for congeneric Maccullochella species. Here we develop a novel set of 15 microsatellite loci specific to M. mariensis, and demonstrate that these markers exhibit higher variability than those used previously. Mean number of alleles per locus was 4 and mean expected heterozygosity was 0.57. We genotyped 35 Mary River cod larvae belonging to a single cohort using the 15 novel loci and eight previously used loci, and found 10 full‐sib family groups along with clear genetic differentiation between individuals collected from the two sub‐catchments – Tinana Creek and Mary River. Microsatellites presented here will be useful for cost‐effective monitoring of genetic diversity and recruitment dynamics in this endangered fish species. [ABSTRACT FROM AUTHOR]

From February to October 2016, a total of 9,754 fish specimens were collected from the Yiluo River, a tributary of the Yellow River, China's second longest river. Based on these samples, length-weight relationships ( LWRs) and length-length relationships ( LLRs) were estimated for 26 species. Among these data, LWRs for 1 species, LLRs for 11 species, and maximum total lengths for six species were not previously recorded in FishBase. The a values of the LWRs varied between 0.0019 and 0.0116, and b values from 2.805 to 3.883. All regressions for LWRs and LLRs were highly significant ( p < .001). These results will be useful for sustainable management and conservation of the fish resources in the Yiluo River and the Yellow River ecosystem. [ABSTRACT FROM AUTHOR]

The article talks about Australian smelt Retropinna semoni, a common freshwater fish species found throughout southeastern Australia. It mentions that 21 polymorphic microsatellite markers were developed to study the the migratory life history patterns of these species. These markers will help understand southern smelts, who are an ecologically variable taxonomic group and that conservation and management actions should take as per migratory behaviours.

The paper reports the length-weight relationships of 55 species from the Three Gorges Reservoir ( TGR) of the Yangtze River, China, and the largest reservoir in the world. A total of 24,176 specimens were collected from July 2012 to January 2015. Length-weight relationships for 33 fish species not recorded previously in FishBase, and the maximum total lengths computed for eight species are presented. The a values varied between 0.00054 and 0.01923, and the b values ranged from 2.729 to 3.583. The results will be useful for the application of sustainable management and conservation of these fishes in the TGR of the Yangtze River. [ABSTRACT FROM AUTHOR]

Summary: Length–weight relationships (LWRs) were determined for four fish species from two drainage areas, those of the Itapemirim and Jucu River, in the state of Espírito Santo, southeastern Brazil. Fishes were collected between May 2015 and November 2016, with gill nets, casting net, dip net, and sieve. Herein are presented LWRs for Astyanax lacustris, Astyanax taeniatus, Hyphessobrycon bifasciatus and Oligosarcus acutirostris. [ABSTRACT FROM AUTHOR]

Habitat selection has been quantified for age-0 and adult pallid sturgeon Scaphirhynchus albus Bull. Illinois State Lab. Nat. Hist., 7, 1905, 37, but little is known regarding habitat use of the juvenile fish. The objective of this study was to quantify habitat use and selection of juvenile pallid sturgeon in the Missouri River, Nebraska, USA. Thirty-seven age-4 pallid sturgeon with transmitters were released in July of 2014, plus an additional 21 in September, with habitat monitored using biotelemetry. Age-1 and age-4 hatchery reared pallid sturgeon were found to avoid areas associated with the outside bend and thalweg habitats that were characterized by rapid water velocity (>1 ms−1), which accounted for 50% of the area in the channelized Missouri River. Age-1 pallid sturgeon selected an off-channel habitat and inside bend habitat while age-4 pallid sturgeon selected an off-channel and inside bend channel border habitat. Juvenile pallid sturgeon in unaltered rivers have been shown to associate with island tips and sand bars, habitat that is largely absent in the channelized Missouri River. This study indicates that juvenile pallid sturgeon in the Missouri River, Nebraska are selecting habitats with shallow water and slow water velocity, similar to those associated with island tips and sand bars in unaltered reaches. [ABSTRACT FROM AUTHOR]

This work contributes to the knowledge of the reproduction, growth parameters and mortality rates of Iheringichthys labrosus in a newly-formed reservoir. A total of 554 males and 1227 females were collected over 12 consecutive months, 1998-1999, from sites in the Corumbá Reservoir, Brazil, using gillnets (meshes: 2.4-16 cm). Information on each individual, i.e. standard length (cm), weight (g), sex, and gonadal development phase was recorded. The pectoral spines were removed to estimate age. The number of juveniles and adults, males and females, reproductive sites and seasons were estimated. First maturation length was estimated using a likelihood function fitted by binomial distribution. Growth parameters were estimated using the von Bertalanffy equation. Total instantaneous mortality was obtained through a linearized catch curve method. Standard length varied from 6.0 to 20.5 cm. Growth showed negative allometry for both sexes. The reproduction period was August to December in all environments sampled and first maturation length was 11.5 cm. All individuals were adults with 17.0 cm standard length. Ages varied from zero to 7 years. Asymptotic length, growth coefficient and t0 for the entire population were 27.79 cm, 0.12 and −2.64, respectively. Instantaneous and annual mortality rates were 0.90 and 0.59, respectively. [ABSTRACT FROM AUTHOR]

Length-weight relationships ( LWR) using 3876 individuals were determined for 39 species sampled in estuarine systems in the main Hawaiian Islands, including 33 species of fish from 21 families, five species of crustaceans (prey) from two families, and one mollusk species. For 17 species, LWRs were estimated for the first time. For another 14 species their LWRs were newly reported for Hawaiian waters, including seven introduced taxa that are well established in the islands' estuaries. The LWRs for all taxa include juvenile and sub-adult size ranges commonly encountered in Hawaiian estuaries. [ABSTRACT FROM AUTHOR]

The movement of Atlantic bluefin tuna ( ABFT) across international boundaries necessitates traceability strategies that would provide more accurate information needed for stock assessment. The Mediterranean Sea is one of the main contributors to ABFT reproduction and global population genetic diversity. In the present study this genetic variability was investigated using 193 samples of adult bluefin tuna from Spain, Turkey and Malta - a longitudinal distance of 3400 km. Analysed were 13 microsatellite loci (eight of which were newly-tested) as genetic markers for the population study. Allele richness measured per locus and sampling location varied from 1.89 to 8.88, taking into account rarefaction. ABFT private alleles were detected in each of the three sampling sites. No significant spatial genetic divergence was found between pairs at the studied locations ( FST values <0.0001; P-values >0.05). Bayesian clustering analysis corroborated a single and panmictic ABFT population in the Mediterranean Sea. Statistical power analyses indicated a high probability of detecting genetic differentiation and population structure with the sample size and microsatellites used, even at an FST value of 0.005. From the results it may be postulated that migrating ABFT during the spawning season are allowing gene flow within the Mediterranean Sea. The complex interplay of movements, including plasticity in the selection of spawning sites with increasing age and environmental conditions, require multiple and new fisheries monitoring and management techniques in order to target the ABFT long-term conservation effectively. [ABSTRACT FROM AUTHOR]

The skeleton of cartilaginous fishes is notoriously difficult to prepare, and the literature dealing with the subject is extremely rare compared to other vertebrate groups. As a result, chondrichthyan skeletal specimens held in museums and other scientific institutions are often limited to isolated sets of jaws, taxidermised specimens and small individuals preserved whole in fluid. However, skeletal characters are heavily relied upon in several taxonomical and phylogenetical analyses, highlighting the importance of properly prepared skeletal specimens in research collections. The relevant literature is briefly reviewed herein, with a proposal for a new and simple protocol involving limited and easily obtainable chemicals, for the quick preparation of clean and durable chondrichthyan skeletal specimens. Various features of the chondrichthyan skeleton are also discussed, along with the microstructural effects of the chemicals involved in the protocol. [ABSTRACT FROM AUTHOR]

This study evaluates the catch rates, species composition and reproductive biology of flotsam-associated fishes targeted by ring nets off the southwest coast of Sri Lanka. Catch and number of multiday boats operating with ring nets were collected at Beruwala fishery harbor on the southwest coast of Sri Lanka, March to October 2013, by making fortnightly field visits. Fish samples were collected randomly from the unloaded ring net catches to analyze reproductive biology. Twelve fish species belonging to four major families: Scombridae, Carangidae, Coryphaenidae and Balistidae were identified in the ring net catches and five species, Decapterus russelli, Katsuwonus pelamis, Thunnus albacares, Elagatis bipinnulata and Canthidermis maculatus were predominant. An average of 25 ± 12% multiday boats landing at the Beruwala fishery harbor operated with ring nets each month, with an average monthly catch rate fluctuating from 730 ± 101 to 3924 ± 1094 kg per boat per trip. Catch rates of tunas and carangids were significantly higher than the other fish groups ( anova; d.f. = 3, P < 0.05). Total fish landed by ring nets at the Beruwala fishery harbor during the study period was 1456 tonnes. Species belonging to the family carangidae had the highest percentage contribution (46.6%) to the ring net landings followed by tuna (34%). Similar-size individuals ranging from 24 to 31 cm were landed by ring nets, with all landed individuals belonging to K. pelamis, T. albacares and E. bipinnulata having immature gonads. The findings of this study will be useful locally as well as regionally to manage the ring net fishery and to aid in implementing measures to manage the highly migratory tuna species. [ABSTRACT FROM AUTHOR]

In response to the global sustainability drive to lower fishmeal ( FM) inclusion in aquatic feeds, exogenous enzymes can improve nutrient digestibility in monogastric plant-based diets. A 80-day experiment was conducted to evaluate the combined effects of xylanase and phytase on digestibility, trace mineral utilisation and growth in juvenile red tilapia, Oreochromis niloticus x O. mossambicus, (48.8 g ± 13.9; μ ± STD) fed declining FM diets. Basal diets were formulated to contain 0, 3 and 5% FM with and without xylanase (0.385 g kg−1) and phytase (0.075 g kg−1), forming six treatments. Each treatment was randomly assigned to four replicates, 20 fish tank−1; mean water temperature 28.98 ± 0.73°C. Although the size of the effects was modest, growth performances (feed intake, FCR, growth rate) decreased with lower FM levels (P < 0.05) but improved with enzyme supplementation. Enzyme supplementation increased P digestibility and trace mineral uptake (P < 0.05), but no effects were seen on protein digestibility and N retention. Nevertheless, tilapia fed the enzyme-supplemented 3% FM and control 5% FM diets performed comparably (P < 0.05). This potentially justifies a 2% FM reduction for tilapia diets using exogenous xylanase and phytase without significant effects on digestibility, trace mineral utilisation and growth. [ABSTRACT FROM AUTHOR]

Hucho bleekeri is a critically endangered salmonid fish found in the Yangtze River drainage in China. In this study, the genetic diversity of a small population (n = 43) was first assessed with partial mitochondrial DNA sequences (D-loop region and a cytochrome b gene [ CYTB] gene fragment) and 15 microsatellite markers. Low levels of nucleotide diversity ( Pi) were demonstrated in the H. bleekeri population based on the two mitochondrial DNA markers. The number of haplotypes ( h) and the haplotype diversity ( Hd) in the D-loop region (12 haplotypes and Hd = 0.8208) were higher than in the CYTB gene fragment (three haplotypes and Hd = 0.0941). The number of microsatellite alleles ( Na) ranged from 2 to 13 in these individuals. The mean observed heterozygosity ( Ho) and the expected heterozygosity ( He) were 0.59719 and 0.44735, respectively. Analysis of molecular variance showed that the degree of differentiation in the population was low ( FST = 0.04041) and the coefficient of inbreeding ( FIS) was negative, indicating no obvious evidence of inbreeding in this population. A demographic assessment suggested that this species expanded a long time ago, but has suffered great losses in recent years. A molecular phylogenetic analysis clearly indicated that H. bleekeri is not introgressed by Brachymystax lenok tsinlingensis. The baseline population genetic information supplied by this study will be vital in monitoring this highly threatened species. [ABSTRACT FROM AUTHOR]

Stock enhancement efforts have been used to aid in increasing dwindling population levels of Lake Sturgeon, Acipenser fulvescens, that are currently of conservation concern. Consistent monitoring of stock enhanced fisheries requires a reliable and reproducible method to mark stocked fish such that the success of such programs can be determined. Recently, stable isotopic marking of hard structures in fish has been developed in a variety of species, however, optimal marking conditions are less well understood. In this study the metabolism of strontium in juvenile Lake Sturgeon and determined parameters for optimisation of marking success in the fin ray were examined. Using radioactive strontium (85Sr), whole body influx and efflux rates of strontium were 3.02 ± 0.364 pmol h−1 g−1 (mean ± standard error) and 0.04 ± 0.007 pmol h−1 g−1, respectively. Furthermore, short-term accumulation of 85Sr in a variety of tissues was assessed and found to be greatest in the fin ray. Biological half-life of the stable isotope 86Sr was shortest in muscle and longest in the fin ray tissue. Immersion and length of immersion timing had positive relationships with marking success. Additionally, the signature remained in 75% of fish analysed 550 days post-mark. Data suggest that marking success was determined by duration of immersion in the mark and concentration of the mark introduced to the water. [ABSTRACT FROM AUTHOR]

The article focuses on a study conducted for a requirement of conservation monitoring of population and habitat utilization of sea lamprey Petromyzon marinus fishes in chalk streams of Great Britain. Topics include population decline of fishes due to river fragmentation and habitat loss, utilisation of spawning habitats, migration of fish species, observation of water temperature, nest counting in chalk streams and rivers and assessment methodologies for protection of spawning habitats.

The present study provides the length-weight relationships ( LWRs) for 64 fish species belonging to eight families from the lower sections of Wujiang River, a tributary of the upper Yangtze River in China. LWRs for eight of these species are unknown to FishBase and new maximum body weights are recorded for 25 species. In addition, some basic biological information on 64 fish species is also summarized. These results will be useful for fishery research, management and conservation in the Wujiang River. [ABSTRACT FROM AUTHOR]

The influence of environmental variables on native and exotic fish species richness and diversity was analysed 8 years after one of the most environmentally harmful toxic spills worldwide. Environment-diversity relationships were addressed on different scales, and values were also compared with those of six similar basins not affected by the spill, with the aim of determining whether this disturbance was still exerting an influence on the fish assemblage. Results showed higher native species richness in environments with low human influence, no reservoirs upstream, a large drainage area and coarse substrate reaches. For native fish, variables at both the catchment and site were equally relevant. Exotic fish were mainly favoured by site-scale factors such as valley width downstream from the reservoir, where the alteration of the river channel and accumulated disturbances give them an advantage vs native species. Overall, 8 years after the accident, richness and diversity of the Guadiamar fish assemblage seemed more affected by anthropogenic impacts than by the long-term influence of the toxic spill. This work highlights that the potentially synergic effects of anthropogenic factors must be taken into account when monitoring the long-term effects of pollution events. [ABSTRACT FROM AUTHOR]

Species distribution models and consensus models allow knowing the distribution of species in large areas where there is no field data and identifying the most important drivers for those distributions. In this study, seven individual models were used to obtain a consensus model to determine the potential distribution for six freshwater fish species in several watersheds of Northern Spain. Moreover, three different methods of model evaluation were used for performance comparison. Fish data were obtained from databases provided by different organisms related to aquatic systems containing information on 759 field sites sampled between October 2002 and June 2011 using electrofishing techniques. Dependent variables were obtained after filtering field sites according to a human pressure gradient analysis, while independent variables were derived from a Synthetic River Network for the study area. The 'best' individual models were obtained using Random Forest, Generalized Boosted Models and Generalized Additive Models, but with differing results among species and evaluation methods. The different consensus models revealed a high degree of adjustment between modelled and observed data. The most important factors related to fish distributions were the width of the valley floor, mean annual flow, average catchment elevation, distance to the sea, and total catchment area. The importance and critical limits of presence-absence for these key variables differed among species. Use of these models could assist in the prioritization and selection of specific catchment and river reach actions for fish population management, restoration and/or conservation. [ABSTRACT FROM AUTHOR]

Habitat suitability models ( HSM) are concerned with the abundance or distribution of species as a consequence of interactions with the physical environment. Generalized Additive Models ( GAMs) were used to model brown trout ( Salmo trutta L.) density as a function of environmental variables at the scale of river reach and hydromorphological units ( HMU) in the Júcar River Basin (Eastern Spain). After 4 years of observations (2003-2006) the data representing trout density were split into two categories, young (<2 years) and adult (≥2 years), for modelling independently. The environmental descriptors at reach-scale described the geographical position, hydrological conditions, proportions and diversity of habitats. At the scale of HMUs (pool, glide, riffle or rapid), habitat descriptors representing dimensions, substrate, cover and velocity were used. The best and parsimonious GAM for each category was selected after a comprehensive trial of all possible combinations of input variables. The models explained 61% (adult) and 75% (young) of the variability of the data ( R2adj). The results demonstrated the relevance of mean width, mean depth, cover index, mean velocity and slope for adult brown trout. Young trout densities were mainly related to maximum depths, cover index, mean velocity, elevation, average distance between rapids and number of slow water HMUs. This article shows the relevance of considering geographical and habitat-related requirements at different scales to describe the patterns of trout density. Furthermore, the importance of considering non-linear relationships with habitat variables was demonstrated. The results are useful for environmental managers to design effective and science-based restoration measures, and result in a more efficient management of brown trout populations. [ABSTRACT FROM AUTHOR]

The number of threatened freshwater fish species in Spain is among the highest recorded in Europe and includes a high percentage of endemic taxa. Investigated were the distribution of Spanish freshwater fish to identify priority areas for conservation and assess the extent to which freshwater fish are included in the existing network of protected areas. Considered were those threatened species recorded in the Spanish National inventories. From these data, several biodiversity indices were calculated and analysed. The results reveal important discrepancies between the national and international assessments of conservation status, whereby the current Spanish national catalogue needs updating to reconcile these inconsistencies. Several important areas for the conservation of freshwater fish lie outside protected areas. The results encourage the establishment of protected areas specifically for freshwater environments. An extensive database of Spanish freshwater fish species is needed to redefine priority areas and to maintain freshwater biodiversity. [ABSTRACT FROM AUTHOR]

The article presents a study which discussed re-discovery of fish species in Croatia including Telestes miloradi and Delminichthys ghetaldii. Topics discussed include need of protection of newly found species, field research conducted in waterbodies in Konavosko polje, and threat to the populations of D. ghetaldii due to plan to build an underground hydro power plant.

Summary: Length‐weight and length‐length relationships were investigated for 13 freshwater fish species from the lower Jinsha River, southwest China (from 101°32′49.63″E; 26°35′38.27″N to 104°37′48.14″E; 28°45′59.55″N). Fish were sampled from five sites during 2014 and 2016, using trap‐nets, gillnets (major mesh size: 2–6 cm), longline and electrofishing. Length‐weight relationships for six and length‐length relationships for 12 species are the first report to FishBase, respectively. Moreover, new maximum length for 11 species are also presented to FishBase in this study. All regressions were highly significant (p < .001), with the coefficient of determination r2 > .950. These information will be helpful for management and conservation in local fishes and fisheries. [ABSTRACT FROM AUTHOR]

Summary: Length‐weight relationships (LWRs) are reported for nine fish species belonging to four families from the upper reach of the Gan River, one of the main tributaries of the Yangtze River, China. A total of 807 specimens were collected from April 2016 to July 2017. Fishes were both sampled using a backpack electrofishing unit and collected from local fish markets that using various fishing gears such as electrofishing boats, gillnets (mesh sizes: 1–12 cm), hooks, and benthic fyke nets (mesh sizes: 0.5 cm and 0.7 cm). The fish species were Siniperca undulata (Fang & Chong, 1932), Pseudogobio vaillanti (Sauvage, 1878), Sarcocheilichthys parvus (Nichols, 1930), Barbodes semifasciolatus (Günther, 1868), Spinibarbus hollandi (Oshima, 1919), Gobiobotia meridionalis (Chen & Cao, 1977), Pseudobagrus albomarginatus (Rendahl, 1928), Pseudogastromyzon changtingensis (Liang, 1942), and Pseudogastromyzon fangi (Nichols, 1931). The a values for the nine species varied between 0.0056 and 0.0366, the b values ranged from 2.333 to 3.318, and r2 values from .952 to .994. [ABSTRACT FROM AUTHOR]

The morphometric relationships of three native and one exotic freshwater fish species from the Lower San Juan and Lower Pisco River basins, central Coast of Peru, are presented. Specimens were collected in May and November 2010 using seine nets and electrofishing. Length-Weight ( LWR) relationships for Andinoacara stalsbergi, Trichomycterus punctulatus, Basilichthys archaeus and Poecilia reticulata are provided for the first time, contributing information towards the effort to conserve freshwater fishes. [ABSTRACT FROM AUTHOR]

A market survey was performed on caviar from Romania and Bulgaria, two of the last range states of critically endangered sturgeons threatened by poaching and illegal trade. Twenty-seven samples were collected between April 2011 and February 2012, including two samples of Bulgarian farm caviar bought in an Austrian fish shop. Mitochondrial sequences of the cytochrome b gene and microsatellites were used for species identification. Ten samples were in agreement with the species code on their CITES labels, but four samples were mislabeled, six samples were counterfeit and four samples were offered as 'wild origin,' ignoring the fishing bans in place. At least one sample was upgraded from a lower priced species to a more expensive species. These results demonstrate the weakness of sturgeon protection in these Member States of the European Union and key range states. Therefore, we recommend intensifying conservation and enforcement efforts, including also DNA testing of caviar in containers with apparently correct CITES labels. [ABSTRACT FROM AUTHOR]

An experimental release of 1192 hatchery-reared, individually PIT tagged, 220 days old (296-337 mm TL) Gulf sturgeon, Acipenser oxyrinchus desotoi, was undertaken in 1992 in the Suwannee River, Florida. The original objectives of the 1992 release experiment were to: (1) evaluate survival rate of cultured Gulf sturgeon in the wild vs survival rate of their wild 1992 cohort counterparts, (2) determine the differential effect of release site within the river upon long-term survival, and (3) evaluate comparative growth rates of recaptured hatchery vs captured wild 1992 cohort Gulf sturgeon. The present investigation addressed those original objectives, plus an additional fourth objective: (4) evaluation of hatchery fish recapture rate change over the 19-year experiment. The primary objective was to determine efficacy of potential conservation aquaculture for this species in terms of long-term survival in the wild. Follow-up 1993-2011 gill net sampling in freshwater reaches (rkm 4-237) and the estuarine river mouth (rkm −6 to 4) yielded recaptures representing 13.0% of the total released. Mean annual hatchery fish mortality (including emigration) rate estimated for the 19-year period (1993-2011) was more than twice that for same cohort wild fish. Mark-recapture survival probability (phi) for hatchery fish, 1993-2011, was substantially lower (0.733) than for their wild counterparts (0.888). Mean annual hatchery fish recapture rate, as a percentage of all 1992 cohort fish recaptures, declined significantly after age-7, coinciding with age of onset of migration into the open Gulf of Mexico. Hypothesized causal factors may be differentially lower fitness in the marine habitat or permanent outmigration due to natal river imprinting failure. Hatchery fish recapture rates varied significantly for fish from the ten release sites, being highest near the river mouth, and lowest for the furthest upriver sites in the Suwannee River and its Santa Fe River tributary. Hatchery fish also displayed a significantly lower growth rate than their wild counterparts through age 3000 days. Cumulative hatchery fish mortality of 99.87% over 19 years predicts <3 individuals would have survived through 2011. From the results of the 1992 release experiment, hatchery supplementation as a Gulf sturgeon conservation measure does not appear to be an effective option. [ABSTRACT FROM AUTHOR]

Information about several papers discussed at the 7th International Symposium on Sturgeons organized by Vancouver Island University and the World Sturgeon Conservation Society held in British Columbia on July 21-25, 2013 is presented. Topics include sturgeon conservation programmes, habitat deterioration and river fragmentation and destruction. Other topics discussed include watershed connectivity and disruption of river flows, cross-border water system management and sustainability measures.

Diel variation in habitat use of subyearling Chinook salmon ( Oncorhynchus tshawytscha), subyearling coho salmon ( O. kisutch), yearling steelhead ( O. mykiss), and yearling Atlantic salmon ( Salmo salar) was examined during the spring in two tributaries of Lake Ontario. A total of 1318 habitat observations were made on juvenile salmonids including 367 on steelhead, 351 on Chinook salmon, 333 on Atlantic salmon, and 261 on coho salmon. Steelhead exhibited the most diel variation in habitat use and Chinook the least. Juvenile salmonids were generally associated with more cover and larger substrate during the day in both streams. Interspecific differences in habitat use in both streams occurred with Atlantic salmon (fast velocities) and coho salmon (pools) using the least similar habitat. Chinook salmon and Atlantic salmon used similar habitat in both streams. These findings should help guide future management actions specific to habitat protection and restoration of Atlantic salmon in Lake Ontario tributaries. [ABSTRACT FROM AUTHOR]

Length-weight and length-length relationships are reported for seven fish species belonging to four families and seven genera from the Irtysh River and its tributaries, northwest China. A total of 1,351 individuals were collected using three layers of drift gill nets (inner mesh size 13 cm, outer mesh size 26 cm), set gillnets (mesh size 2.5 cm), and purse net (mesh size 1 cm) on a monthly basis from April to October 2013. One length-weight relationship, five length-length relationships, and two maximum lengths are presented for the first time in FishBase. This biometric data and their relationships are relevant to the management and conservation of local fishes and fisheries. [ABSTRACT FROM AUTHOR]

The lake sturgeon, Acipenser fulvescens, is a threatened species across most of its range. To understand any potential shifts in diet across season or habitat, stomach contents were examined from juvenile lake sturgeon caught in the Winnipeg River, Manitoba, Canada. This information will aid in assessment of environmental impacts and conservation initiatives for this threatened species. From 2006 to 2008 gut contents were collected from juvenile lake sturgeon using a non-lethal gastric lavage methodology. Juvenile lake sturgeon were sampled from four discrete deep water habitat types (13.7-27.4 m depths), during the months of May, June, July and October. In total, 13 066 prey items belonging to 14 prey groups were collected from 345 juvenile lake sturgeon (251-835 mm TL). Overall, juvenile lake sturgeon consumed a low diversity of organisms; insect larvae from three invertebrate orders, Trichoptera, Diptera and Ephemeroptera, accounted for 97.4% of the total numeric abundance of prey items recovered. A relationship between size of juvenile lake sturgeon and prey quantity or type was not observed. Diet of juvenile lake sturgeon varied in relation to season, with Diptera (77.6%) being the most abundant prey in May, Trichoptera the most abundant in June (n = 3,056, 60.4%) and July (n = 2,055, 52.6%). During October, 96% of stomachs examined were empty. In terms of habitat type, the standardized abundance of invertebrate prey items was highest in deep water habitats characterized by medium water velocity (depths > 13.7 m) and coarse substrate (particle sizes > 0.063 mm) in May and June when compared to deep water habitats characterized by low water velocity (<0.2 m.s−1) and fine substrate (particle sizes < 0.063 mm). However, in July, the opposite was observed and prey abundance in juvenile lake sturgeon stomachs decreased with increasing particle size. Results suggest a high degree of dietary overlap among juvenile lake sturgeon from multiple size/age classes occupying deep-water habitats of the Winnipeg River. [ABSTRACT FROM AUTHOR]

The silver pomfret ( Pampus argenteus) is a commercially important species native to the Indo-western Pacific area. In the present study, the genetic structure of five P. argenteus populations from the Arabian Sea, Bay of Bengal, and South China Sea were investigated using sequences of the mitochondrial cytochrome c oxidase subunit I ( COI) gene. All populations showed high levels of haplotype diversity ( h) and low levels of nucleotide diversity ( π). Phylogenetic trees indicated that the haplotypes could be divided into three clusters, indicating the geographic distribution of the five populations. Analysis of molecular variance ( amova) indicated the intra-region variation among these populations to be highly significant. The average pairwise differences and Fst values among the three regions were also found to be significant. These results suggest that P. argenteus in these regions has strong geographic genetic structure. The present results provide new information for the genetic assessment, fishery management, and conservation of this species. [ABSTRACT FROM AUTHOR]

Body length and weight relationships were estimated for sixteen native freshwater fish species (ten Characidae, three Loricariidae, two Heptapteridae and one Astroblepidae, mainly small-sized fish) collected in the Andean piedmont Hacha River (Caquetá, Colombia) by electrofishing. These are the first length-weight and length-length parameters reported for the species, which are mostly endemic to the Amazonian basin. Maximum lengths in eight of the sixteen studied species are also reported. Knowledge of this biometric data and their relationships can be relevant in the management and conservation of the local fish and fisheries. [ABSTRACT FROM AUTHOR]

Summary Large fish species are at high risk of extinction because of life cycle characteristics and migratory fishes are often vulnerable to river modifications and overexploitation. The freshwater fish family Cyprinidae has the highest diversity in species, varied morphological and behavioral properties, and a wide range of habitat requirements. This study included an analysis of the conservation attention on large, migratory cyprinid species, a summary of threats jeopardizing the endangered species in this group, and a case study on little known species from northwest China. About 1% of all cyprinid species exceed 1 m in total length, and most of these fishes have migratory behaviors. Most of these species (79%) have not been evaluated for conservation attention, and a minor portion that have been evaluated were considered endangered. The threats to large migratory cyprinids include all the common threats to freshwater biodiversity: overexploitation, habitat alteration, water pollution, flow modification, and species invasion. The first two threats explain most of the decline in abundance and range of large, migratory cyprinids, and the others are sometimes important. The case of the Xinjiang datou fish ( Aspiorhynchus laticeps) illustrates how an impressive species can be lost without much scientific or public attention. The analysis of conservation attention, threats, and the case study support the conclusion that large, migratory cyprinids are not receiving conservation efforts that should be focused on fish species that are especially vulnerable to human impacts. [ABSTRACT FROM AUTHOR]

Summary Anthropogenic activity has played a preponderant role in limiting and reducing the adaptive potential of species, resulting in an accelerated loss of biodiversity. Fish species, in particular anadromous, are especially sensitive to environmental disturbance and are often heavily exploited. In this review, we describe: (i) the main threats to anadromous species; (ii) the principal conservation actions that are usually implemented to restore populations, as well as their main pitfalls; (iii) the most relevant population parameters in terms of conservation genetics; (iv) the main genetic tools available to evaluate those parameters; and (v) some empirical studies highlighting the usefulness of genetic tools in conservation management. In terms of conservation actions, we promote the view that priority should be given to ecological restoration, while stocking should only be performed under very strict conditions and accompanied by adequate management and monitoring. Finally, we call attention to the importance of considering the evolutionary potential of populations in conservation decisions. [ABSTRACT FROM AUTHOR]

Summary Until 2003 Cottus perifretum was believed to be extinct from the Demer River basin in Flanders, Belgium. However, that year a relict population of this bullhead species was found in the Dorpbronbeek. The Research Institute for Nature and Forest (INBO) and the Agency for Nature and Forests (ANB) launched a conservation project to preserve this population by re-introducing cultured progeny to the Zevenbronnenbeek. This headwater stream was carefully selected from seven evaluated potential locations within the Demer River basin based on water and habitat quality and food availability. In October 2008, 1220 cultured age 0+ bullhead were released. To enlarge the chance for success, ceramic roof tiles were added to the stream as artificial spawning substrates. In 2009, the success of the re-introduction was assessed. The recaptured fish had grown since their release and were in visual good condition, but most important, natural reproduction occurred. [ABSTRACT FROM AUTHOR]