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The bluntnose sixgill shark (Hexanchus griseus) is a wide‐ranged deep‐water shark species found off continental and insular shelves. Despite its global distribution, little is known about the reproductive ecology of the species, particularly with regard to the location and timing of important phenological events such as mating and pupping. In this study, we report the landing of a neonate H. griseus individual from an artisanal fishing camp in Baja California Sur, Mexico. This represents only the ninth confirmed record of the species from the Mexican Pacific and the first to report a neonate specimen in Mexican waters. We discuss this specimen in the context of the environmental conditions in which it was found, ultimately suggesting that these shallow coastal waters may be an important pupping ground for H. griseus in the region. Furthermore, the specimen was found during the winter months (whereas all previous reports have suggested H. griseus pups during the summer), implying regional variation in reproductive periodicity, or the presence of multiple reproductive events per year. This study provides novel insight into the reproductive biology of H. griseus and the ecological characteristics of the species in the Northern Mexican Pacific. [ABSTRACT FROM AUTHOR]

Elasmobranchs are slow‐growing marine predators whose populations have declined due to their susceptibility to overfishing, especially affecting species of large size. Rostroraja alba is a large skate that is currently classified as critically endangered.To address the effects of overfishing and promote the recovery of marine species and habitats, marine protected areas (MPAs) are a commonly implemented management strategy. A critical aspect of their success is using information on species' movement patterns; however, this is frequently not assessed for elasmobranchs.In this study, acoustic telemetry was used to monitor 30 R. alba in the Professor Luís Saldanha Marine Park (Portugal) to assess their long‐term movements in the context of a coastal MPA and to evaluate the contribution of this kind of spatial management to the conservation of this species.Immature individuals were more frequently captured than adults, which postulates this area as a potential nursery. The average residency was moderate and relatively consistent throughout the year, as was area use. No marked size or sex‐based differences in movement were noted. Individuals were more active and occurred in shallower waters at night and twilight, and occasional quick vertical movements into the water column, isolated or in sequence, were also noted.In general, the LSMP seems to offer stable protection to immature R. alba, with no strong seasonal variation. These results provide relevant input for adaptive management measures of this and other similar MPAs and highlight the contribution of these efforts to the protection of nursery areas. [ABSTRACT FROM AUTHOR]

This study delves into the foraging ecology of the cookiecutter shark (Isistius brasiliensis) in the Saint Peter and Saint Paul Archipelago (SPSPA), assessing bite marks on pelagic fishes collected between March and September 2018. Examination of 200 individuals from five species revealed the shark's predilection for targeting adult fish, ensuring efficient removal of energy‐rich tissue layers. However, a notable exception is Thunnus albacares, preyed on predominantly during its juvenile stage, possibly due to vertical spatial segregation. Recent bites were pervasive across species, with wahoo displaying a distinctive pattern. Cookiecutter shark bites predominantly targeted the lateral body portion (>55%) except for yellowfin tuna, which exhibited a preference for the ventral region (95%). The estimated length distribution suggests the SPSPA as a potential nursery area for cookiecutter sharks. Bite mark positions and frequencies may be linked to fish behavior, swimming velocity, and fishing gear strategy, highlighting the complex interplay in pelagic ecosystems. [ABSTRACT FROM AUTHOR]

Sandy beaches have experienced substantial human modifications worldwide for centuries. Yet, sandy beaches are known as nursery areas for coral reef fishes. Due to global and local stressors, the degradation of nurseries such as the sandy beaches may have wide reaching consequences for the resilience of reef fishes. In our study, the impact of erosion vs. accretion phenomena was highlighted on coral reef fish community in Guadeloupe in comparing the abundance and diversity of juvenile fish between two nearby beach sites (one that undergoes accretion and the other one that undergoes erosion since the 1950s). The main result showed that a significant retreat of sandy beach along the entire coastline, by bringing out an old reef, could create new habitats, favorable to the settlement of fish juveniles. This result is surprising when considering that erosion negatively affects coral reefs through the sedimentation, deterioration of water quality, and loss of habitat. [ABSTRACT FROM AUTHOR]

Bonnethead and Caribbean sharpnose sharks frequent coastal waters, rendering them vulnerable to overexploitation, with the bonnethead shark listed as endangered by the IUCN. Marine Protected Areas (MPAs) have been suggested as a management strategy to regulate shark-exploitation. Moreover, it's essential to identify key areas where nursery grounds (NG) and adult habitats overlap to prioritize conservation zones within MPAs. Along the Caribbean Sea, several NG have been identified for larger shark species, but little is known for smaller sharks. In Bocas del Toro (BDT-Panamanian Caribbean), both bonnethead and Caribbean sharpnose sharks are distributed, with the former appearing to be genetically isolated. The local MPA in BDT doesn't include a NG identified near Solarte Island. In this study, to provide ecological information on bonnethead and Caribbean sharpnose sharks within this potential NG, we evaluated stable isotopes (δ13C and δ15N) and total-mercury (THg) values in their fins. The results revealed a higher proportion of small-adult sharks in the NG, emphasizing the necessity of conducting a comprehensive study to further characterize this area. Moreover, there was no niche-partitioning between the two species and their diets primarily consisted of small prey-items, as evidenced by the significant and negative relationship between isotopic values. Both species exhibited low THg levels in their fins. Based on these initial results and previous genetic data, it appears that BDT plays a critical role as a habitat for sharks. Thus, extending the local MPA to cover the potential NG could effectively ensure conservation of bonnethead and Caribbean sharpnose sharks in BDT. [ABSTRACT FROM AUTHOR]

Abstract The bluntnose sixgill shark (Hexanchus griseus) is a wide‐ranged deep‐water shark species found off continental and insular shelves. Despite its global distribution, little is known about the reproductive ecology of the species, particularly with regard to the location and timing of important phenological events such as mating and pupping. In this study, we report the landing of a neonate H. griseus individual from an artisanal fishing camp in Baja California Sur, Mexico. This represents only the ninth confirmed record of the species from the Mexican Pacific and the first to report a neonate specimen in Mexican waters. We discuss this specimen in the context of the environmental conditions in which it was found, ultimately suggesting that these shallow coastal waters may be an important pupping ground for H. griseus in the region. Furthermore, the specimen was found during the winter months (whereas all previous reports have suggested H. griseus pups during the summer), implying regional variation in reproductive periodicity, or the presence of multiple reproductive events per year. This study provides novel insight into the reproductive biology of H. griseus and the ecological characteristics of the species in the Northern Mexican Pacific.

The nursery habitats of the broadnose sevengill shark Notorynchus cepedianus (Péron, 1807) remain largely unknown. The identification of these critical habitats is important for the conservation of these top-down regulator species and general coastal ecosystem dynamics. We investigated the role of the San Antonio cape (Argentina) as a nursery habitat for N. cepedianus and tested the hypothesis that physical conditions (turbidity, sea surface temperature) are more important than prey abundance in the habitat use by young-of-the-year (YOY). We used the presence, relative abundance, and size structure of YOY from a small-scale gillnet fishery (2008–2014) to assess the intra- and inter-annual persistence in habitat use. The results indicated intra- and inter-annual persistence in estuarine habitat use, and comparisons with previous studies suggested that YOYs were more commonly encountered in San Antonio cape than in other suitable areas. Finally, the YOYs' use of the area may be explained by a combination of the spatial–temporal variation in turbidity conditions and food abundance. These results suggested San Antonio cape as a nursery habitat for N. cepedianus YOYs and highlighted the importance of understanding key biophysical effects that regulate the use, movement, and residency of N. cepedianus in their nursery habitats. [ABSTRACT FROM AUTHOR]

Bonnethead and Caribbean sharpnose sharks frequent coastal waters, rendering them vulnerable to overexploitation, with the bonnethead shark listed as endangered by the IUCN. Marine Protected Areas (MPAs) have been suggested as a management strategy to regulate shark-exploitation. Moreover, it’s essential to identify key areas where nursery grounds (NG) and adult habitats overlap to prioritize conservation zones within MPAs. Along the Caribbean Sea, several NG have been identified for larger shark species, but little is known for smaller sharks. In Bocas del Toro (BDT-Panamanian Caribbean), both bonnethead and Caribbean sharpnose sharks are distributed, with the former appearing to be genetically isolated. The local MPA in BDT doesn't include a NG identified near Solarte Island. In this study, to provide ecological information on bonnethead and Caribbean sharpnose sharks within this potential NG, we evaluated stable isotopes (δ13C and δ15N) and total-mercury (THg) values in their fins. The results revealed a higher proportion of small-adult sharks in the NG, emphasizing the necessity of conducting a comprehensive study to further characterize this area. Moreover, there was no niche-partitioning between the two species and their diets primarily consisted of small prey-items, as evidenced by the significant and negative relationship between isotopic values. Both species exhibited low THg levels in their fins. Based on these initial results and previous genetic data, it appears that BDT plays a critical role as a habitat for sharks. Thus, extending the local MPA to cover the potential NG could effectively ensure conservation of bonnethead and Caribbean sharpnose sharks in BDT.

We review published research on the ingress of larvae and early juveniles of marine fishes into estuaries subjected to different tidal regimes and provide perspectives on the abilities and responses of these early‐life stages to the physico‐chemical, hydrodynamic and biological drivers that facilitate such ingress. We focus on documenting ingress and the mechanisms employed by early‐stage fishes from coastal waters to enter different types of microtidal and macrotidal estuaries but also include information on ingress into mesotidal systems. Spawning localities for estuary‐associated marine fishes are assessed with respect to ontogeny of larvae and their ability to ingress estuaries during the preflexion and postflexion stages. The processes and physico‐chemical cues employed by larvae and early juveniles to locate estuaries are reviewed, with olfactory cues being recognised as especially important. Particular emphasis is directed to vertical migratory behaviours and selective tidal stream transport (STST) employed by many larvae ingressing macrotidal estuaries, contrasting with mainly passive flood‐tide entry and active swimming modes typically used by larvae and early juveniles that enter microtidal estuaries and estuarine lakes and lagoon systems. [ABSTRACT FROM AUTHOR]

Nursery areas are essential habitats for sharks, offering protection and increasing the survival of newborns. We conducted interviews with local fishers and collected data from artisanal fishery landings between January 2013 and December 2019 to investigate Chetumal Bay as a nursery area for the bull shark (Carcharhinus leucas) in the Mesoamerican Reef region. The bull shark is a coastal euryhaline shark that inhabits temperate and tropical waters worldwide. In the Mexican Caribbean, bull sharks are caught mainly as bycatch in a multi-specific artisanal fishery using nylon bottomset gillnets, longlines, and hand lines. We record 63 bull sharks in the catches ranging from 67 to 125 cm TL corresponding to immature individuals, 23 neonates with either open or healing umbilical scars (67 and 78 cm TL), and 40 YOY with present but healed umbilical scars (79 to 125 cm TL), with a notable absence of large size juveniles and adults in the catches. Bull sharks were present in landings between May and November; the highest abundance was during July. Our data provide evidence to recognize Chetumal Bay as a nursery area for bull sharks, meeting all the criteria proposed to identify nursery areas. These findings constitute the first documented evidence of a bull shark nursery area in an estuary within the Mexican Caribbean as well as within the entire region of the Mesoamerican Reef System. Moreover, we discuss the importance of this nursery in light of a newly described distinct lineage of bull sharks in Chetumal Bay. [ABSTRACT FROM AUTHOR]

The Pacific coast of Colombia is characterized by mangrove ecosystems which play a crucial role as possible nurseries for juvenile sharks. However, trophic food webs from coastal ecosystems are heavily disturbed by increased fishing pressure, which affects numerous shark species. In this region of the Eastern Tropical Pacific (ETP), fisheries' data from coastal areas are scarce and unspecific, as most sharks from artisanal fisheries are landed decapitated and finless, making their morphological identification difficult. For the establishment and implementation of effective regional conservation and management policies, information on the diversity and population dynamics of shark species is crucial. We therefore sequenced the mitochondrial NADH2 gene of 696 samples taken from fishermen's landings of shark's bycatch along the Colombian north Pacific coast. We were able to identify 14 species of sharks, two of the most abundant species were Sphyrna lewini and Carcharhinus falciformis, both evaluated on IUCN the Red List of Threatened species (Critically Endangered and Vulnerable) and CITES regulated. We found low genetic diversity in the sampled area increasing the concern for both species in the region, even more considering that the majority of individuals were juveniles. Our results showed the importance of genetic markers for first population genetic insights as a complementary tool during the decision-making process in management plans. For this specific region, strategies such as the delimitation of conservation priority areas or the regulation of fishing gears could help improve the sustainability of shark populations in the Colombian Pacific. [ABSTRACT FROM AUTHOR]

The Pacific coast of Colombia is characterized by mangrove ecosystems which play a crucial role as possible nurseries for juvenile sharks. However, trophic food webs from coastal ecosystems are heavily disturbed by increased fishing pressure, which affects numerous shark species. In this region of the Eastern Tropical Pacific (ETP), fisheries’ data from coastal areas are scarce and unspecific, as most sharks from artisanal fisheries are landed decapitated and finless, making their morphological identification difficult. For the establishment and implementation of effective regional conservation and management policies, information on the diversity and population dynamics of shark species is crucial. We therefore sequenced the mitochondrial NADH2 gene of 696 samples taken from fishermen’s landings of shark’s bycatch along the Colombian north Pacific coast. We were able to identify 14 species of sharks, two of the most abundant species were Sphyrna lewini and Carcharhinus falciformis, both evaluated on IUCN the Red List of Threatened species (Critically Endangered and Vulnerable) and CITES regulated. We found low genetic diversity in the sampled area increasing the concern for both species in the region, even more considering that the majority of individuals were juveniles. Our results showed the importance of genetic markers for first population genetic insights as a complementary tool during the decision-making process in management plans. For this specific region, strategies such as the delimitation of conservation priority areas or the regulation of fishing gears could help improve the sustainability of shark populations in the Colombian Pacific.

Sphyrna lewini is a viviparous shark that pups in shallow coastal waters. Given dramatic declines in the S. lewini Eastern Pacific population, it is essential to identify nursery grounds that could potentially increase the resilience of adult populations. Here, we provide evidence of a putative nursery ground for S. lewini at an oceanic island in the Galapagos Marine Reserve. A fortuitous finding of hammerhead shark pups in 2017 led to a series of focused surveys from 2018 onwards, using experimental fishing, baited remote underwater videos stations (BRUVS), and acoustic telemetry, to assess presence and residency patterns of this species at Puerto Grande: a shallow bay at the island of San Cristobal. We caught 66 individuals, of which we measured 54 (mean TL = 52.13 cm). Four individuals were fitted with ultrasonic tags and were detected on an array of 14 receivers in the bay for up to 93 days, showing a high residency index of at least 89%. We actively tracked a single individual for 3 h at night and a further hour a week later. Our results suggest that Puerto Grande is a key habitat for the development of the critically endangered S. lewini. [ABSTRACT FROM AUTHOR]

Batoids comprise five of the seven most threatened families of sharks and rays. The East Asian endemic Naru eagle ray Aetobatus narutobiei is a large bodied ray whose estuarine habitat overlaps with an economically valuable bivalve fishery. In response to decreased bivalve yields, the government initiated a predator control program and as a result, Naru eagle rays have faced intense and targeted fishing pressure during the last two decades. The long-term impacts of the predator control program on the population of rays and bivalves and their balance in the ecosystem are unknown because the life history of the Naru eagle ray has not been characterized. To begin to fill these critical knowledge gaps, the reproductive life history of the Naru eagle was described. Females mature at a larger size than males and require nearly twice as many years to reach maturity (DW50, 952.0 mm vs. 764.2 mm; Age50, 6.0 years vs. 3.5 years). Both males and females reproduce annually and their reproductive cycles are synchronized and seasonal. Females have a single ovary and paired uteri, are viviparous, and reproduce via matrotrophic histotrophy. Mating occurs in August and September and gestation lasts approximately 12 months including a 9.5-month diapause that begins soon after mating and ends in June of the following year, leaving 2.5 months for embryos to complete development. Fecundity ranged from 1 to 7 embryos per brood (n = 158, mean ± SD = 3.36 ± 1.26) and was positively correlated with female disc width (linear regression; F = 105.73, d.f. = 151, P < 0.05). Naru eagle rays are vulnerable to overfishing because of their low fecundity, long reproductive cycle and long time to reach sexual maturity. Obligate embryonic diapause during overwintering and seasonal migrations is a survival strategy that benefits the adults and neonates. This research is a valuable resource to help guide science-based management, conservation and protection of the endemic Asian A. narutobiei and its nursery areas.

Knowledge about top predators’ trophic ecology is crucial for defining their role in ecosystems, understanding habitat preferences, characterizing life stage-specific feeding habits, and evaluating their interaction with fisheries. In the northeastern Pacific, white sharks (Carcharodon carcharias) occupy coastal habitats during the early life stages, including Bahía Sebastián Vizcaíno (BSV) in Mexico, which is a known nursery area. Although BSV presumably provides high prey abundance, the trophic ecology of immature white sharks is poorly understood. Carbon and nitrogen bulk stable isotope analyses (SIA) were used to explore the trophic relationship of early life stages with their potential prey and to infer dietary overlap with sympatric sharks, while SIA of amino acids were used to estimate trophic position. Muscle samples from young white sharks and inshore demersal prey commonly found in their stomach contents were sampled. Demersal prey and literature-derived isotope ratios for pelagic and offshore species were incorporated into mixing models with a Bayesian framework to estimate their contribution to white shark tissues. Nearshore demersal prey had the highest contribution for all life stages (between 35 and 47%), consistent with previous reports based on gut content analysis. The contribution of pelagic (between 26 and 37%) and offshore (between 14 and 32%) prey was smaller and suggests potential periodic changes in foraging grounds and the presence of a maternal-derived isotopic signature. A high contribution of demersal prey indicates a high level of interaction with local fisheries that target those species and catch white sharks incidentally and is consistent with immature shark movement patterns. Isotope ratios of two sympatric sharks, smooth hammerhead Sphyrna zygaena and copper sharks Carcharhinus brachyurus, were used to estimate the overlap in isotopic niche space. Immature white sharks had the smallest isotopic niche, while the highest was for copper sharks. Overlap was greatest between white sharks and hammerheads (∼45%), while overlap with copper sharks was limited (

Despite substantial progress in mobulid research over the past decade, knowledge gaps in manta ray ecology and behaviour remain, particularly in the South Atlantic Ocean. Opportunistic photographic and video records of manta rays collected between 2002 and 2019 at Fernando de Noronha Archipelago (FNA) in northeast Brazil provide evidence to support the year-round use of the region by manta rays (believed to be Mobula cf. birostris). From a total of 130 sighting records, manta rays exhibited feeding behaviour in 36.9% (n = 48) of sightings, indicating that the shallow waters surrounding the archipelago are used as feeding grounds. Approximately half of the records (53.8%) corresponded to identified individuals that were re-sighted repeatedly, using the area in different seasons and for several years. Of the compiled records, 69.2% of sightings were of small individuals (≤3 m disc width). All identified males had undeveloped claspers and females had no visible mating scars, suggesting a juvenile population. Despite being limited to a small local sample, here we present the first report of manta rays at FNA and provide preliminary evidence of feeding behaviour by juvenile manta rays in Brazil. This information contributes to our understanding of the regional distribution and habitat use of manta rays in Brazilian waters. [ABSTRACT FROM AUTHOR]

Characterization of essential habitat for sharks is a key requirement for effective conservation of shark populations. In Cuba, shark essential habitat is largely undocumented. Here we present the first study of a shark nursery area in Cuban waters, for the lemon shark. Nursery areas for lemon sharks are typically surrounded by mangroves and contain sandy substrate where the young can feed, grow, move, and eventually disperse from the area. We conducted our study in Cuba's La Salina Wildlife Refuge during 2015–2019, to understand the role this refuge might play as a lemon shark nursery area, by documenting the distribution and length structure of juveniles. Our results indicate that juvenile lemon sharks are present throughout much of the refuge with no clear pattern of aggregation by size. The size range of all juveniles captured was 39.8–108.0 cm precaudal length (PCL) with a mode in length-class 70.0–75.0 cm PCL. The mean size and weight of all individuals during the study period was 75.8 cm PCL and 5.5 kg, respectively. We infrequently observed neonates in May, June, and September with size range 39.8–55.5 cm PCL. Enforcement of management regulations, difficult access to the refuge for fishers and other user groups, and isolation from human settlements are factors that help maintain nearly pristine conditions in La Salina Wildlife Refuge. The size/age structure of lemon sharks likely represents a population unaltered by human influence. We recommend our study be expanded to contribute to shark conservation and management as outlined in Cuba's National Plan of Action for sharks. [ABSTRACT FROM AUTHOR]

In the past decade along the U.S. East coast, the overfished western North Atlantic stock of Carcharhinus plumbeus has been recovering; however, research investigating C. plumbeus habitats and seasonal habitat shifts is lacking. Accordingly, we studied the seasonal residency, catch abundance, and distribution of juvenile C. plumbeus in Winyah Bay, SC, as well as their migration patterns along the western North Atlantic. We set 303 bottom longlines from May through September in 2016 and 2017 and deployed 11 Vemco (V16-4H) acoustic transmitters in juvenile C. plumbeus. Catch abundance did not differ by month or year (p = 0.45) and was not significantly influenced by any tested water parameter (p = 0.58). C. plumbeus catches were dominated by individuals measuring 81–100 cm precaudal length, and mean size only significantly differed by year (p = 0.02) with slightly larger sharks (86.8 cm PCL) caught in 2017 than 2016 (81.4 cm PCL). Tidal stage and Bay region were positively correlated with catches (p = 0.02). From August 2016 through January 2019, juveniles were detected in Winyah Bay from April to November for 1–302 non-consecutive days (μ ± SE = 108.1 ± 32.6 days), with six juveniles exhibiting interannual return. Detection frequency and presence differed by Bay region, with most detections nearshore and in Lower Bay, fewest in Middle Bay, and none in Upper Bay. This study had two primary findings: monitored sharks utilized a previously unknown southern overwintering migration route, and Winyah Bay serves as a secondary nursery for C. plumbeus. [ABSTRACT FROM AUTHOR]

Generalised additive models (GAMs) were applied to survey data to assess the influence of dissolved oxygen, water temperature and year of sampling upon the presence/absence of small (≤15 cm TL), medium (16–34 cm TL) and large (≥35 cm TL) size classes of deepwater Cape hake Merluccius paradoxus captured off the west coast of South Africa. Data were obtained from surveys using the RV Dr Fridtjof Nansen conducted in 2003 and from 2005 to 2013 during summer (January–February). Among the variables investigated, oxygen was the most important for the small size class (juveniles), with both low and high constraints (two-sided, 'just right' option), whereas for the medium and large size classes the oxygen effects were one-sided (avoiding lows). This finding, in combination with other published information, suggests that the Orange Banks is a nursery ground for juvenile M. paradoxus and that the area covered by this nursery ground can vary with the optimal oxygen concentration. The temperature constraint was generally wider and weaker than that for oxygen, being two-sided for the small and medium hake and one-sided (avoiding highs) for the large hake. The medium hake displayed the greatest tolerance to the investigated variables, which resulted in the widest distribution for this size class. Temperature, oxygen and sampling year play an important role in determining the distribution of M. paradoxus, but details of the biology (life cycle) of the species, such as its pelagic–demersal transition and associated movements, are no less important. [ABSTRACT FROM AUTHOR]

Microbialite pools are dynamic, heterogenous environments with extreme physico-chemical variability in terms of temporal temperature, oxygen and salinity fluctuations. Despite this habitat being hypothesised to be an ecological trap for larvae of marine estuary-dependent fishes, late-stage larvae and early juvenile White musselcracker (Sparodon durbanensis) ubiquitously occur in these pools. This study aimed to investigate the relationship between S. durbanensis density, developmental stage, total length and the physico-chemical environment using a multiple linear regression model analysis. Moreover, it aimed to further explore the potential nursery role of these extreme habitats. All larval and early juvenile stage S. durbanensis were collected with hand nets from pools at three representative microbialite sites on the warm temperate coast of South Africa from late summer to late autumn in 2021. A total of 63 pools were sampled with a total of 57 postflexion larvae and 162 early juvenile S. durbanensis specimens collected. Pool temperatures ranged from 16.6 to 37.3 °C with a mean of 24.5 °C, dissolved oxygen concentration ranged from 5.5 to 26.0 mg/L with a mean of 13.5 mg/L, and salinity ranged from 1.3 to 34.8 with a mean of 25.4. Temperature had a significant positive relationship with total length for early juvenile stages, while none of the other predictor variables showed evidence of a significant relationship with total length. Fish density showed a significant relationship with pool volume for both developmental stages where higher densities occurred in smaller pools that were also characterised by the most extreme physico-chemical variability. Late-stage larvae and early juveniles of this marine fish, that does not use estuaries as a nursery area, appears to complete the larval phase under extreme estuarine-like conditions in microbialite pools. Microbialite pools, as well as adjacent non-microbialite rocky shore pools appear to act as a micro-refuge, possibly improving growth rates and reducing the pelagic larval duration due to warmer water temperatures after which fish move into adjacent deeper, low shore pools and gullies. Due to the extreme conditions in microbialite pools, protection from predators during transition from larval to juvenile stages is also afforded. • Microbialite pools have extreme temperature, oxygen and salinity variability. • Postflexion stage Sparodon durbanensis recruit into high-shore microbialite pools from marine hatching areas. • Warm and hyperoxic pools support late-stage larval grow out of Sparodon durbanensis. • Estuarine-like conditions in microbialite pools are tolerated by postflexion stage larvae of Sparodon durbanensis. • Sparodon durbanensis is absent from estuaries during early life history stages in South Africa. [ABSTRACT FROM AUTHOR]

Myoung, S.H.; Ji, H.-S.; Yu, H.-J.; Kim, H.J.; Kim, H.J., and Lee, B.-R., 2023. Ichthyoplankton assemblage structure in Jinhae Bay, Korea. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, 583-587. Charlotte (North Carolina), ISSN 0749-0208. Many studies on the species composition of ichthyoplankton have been conducted in Jinhae Bay. However, none have focused on the species' composition and distribution patterns. Therefore, herein, the species composition and distribution patterns of ichthyoplankton collected from January to December 2021 from Jinhae Bay, South Sea of Korea, were investigated. An oblique tow was collected from the bottom to the surface using a bongo net (80 cm, 330 µm) from eight stations. The collected samples were identified using morphological analysis and mtDNA cytochrome oxidase subunit I and 16S rRNA sequencing. A total of 66,938 ± 189,267 eggs/1000 m3 (mean ± Standard Deviation, SD) belonging to 30 species and 23 families, and 14,834 ± 31,325 larvae/1000 m3 from 45 species and 25 families, were collected from Jinhae Bay. The dominant egg species were Engraulis japonicus (93.4%), Repomucenus valenciennei (1.5%), and Nuchequula nuchalis (1.2%). Clupea pallasii (92.4%), R. valenciennei (2.5%), and E. japonicus (1.6%) were the dominant larval species. As a result of non-metric multidimensional scaling, fish were divided into two groups: One group spawns during low water temperatures and the other group spawns during high water temperatures. [ABSTRACT FROM AUTHOR]

From May 2003 to February 2005,20 female leopard sharks (78 -140 cm TL) were tagged with acoustic transmitters in Elkhorn Slough, California, and their movements and habitat use were examined using acoustic tracking techniques. Nine sharks were manually tracked for 20-71.5 h, and 11 sharks were monitored for 4-443 d using an array of acoustic receivers. Use of different regions in Elkhorn Slough by tagged sharks changed seasonally and was associated with changes in temperature, salinity, and dissolved oxygen. Sharks used Elkhorn Slough National Estuarine Research Reserve (ESNERR) extensively throughout the year, but especially during the spring and summer. ESNERR appeared to be important as both a foraging and nursery area, likely due to the abundance of intertidal mudflats. Movements and habitat use were tidally influenced, and likely were related to the distribution of important prey items in Elkhorn Slough.

Estuaries are renown sinks or repositories of contaminants and reflect historical pollution of persistent compounds. In particular, mercury (Hg) contamination is widespread in coastal environments and occurs in both inorganic (THg) and highly toxic organic forms (OHg) with high bioaccumulation potential. Trophic magnification factors have been increasingly used to quantify biomagnification and represent the average rate of change in contaminant concentration throughout a food web. Here, we assessed small-scale spatial variation in THg and OHg concentrations, as well as variations in local trophic magnification factors in three segregated areas of the Tejo estuary. Selected sites covered a gradient of contamination from industrial Hg hotspots to a natural reserve area, and are key nursery areas for multiple fishes. We analyzed concentrations in sediment and biota, representing the entire local food webs. Samples included sediments, primary producers (salt marsh plants), primary consumers (macrobenthic invertebrates) and top consumers (fish muscle and liver), and the trophic web structure was characterized via SIAR mixed-modeling of nitrogen and carbon isotopic ratios. Spatial variation in Hg concentrations was observed in sediment and biota (but not for all species), with highest concentrations in the area near historical mercury input. Hg concentrations increased with trophic level, and so did the OHg fraction (% of OHg relative to THg), with mean maximum values up to 48.7 and 94.9% in invertebrates and fish, respectively. Trophic magnification factors were positive for all sites (p < 0.05 for all regressions), ranging between 1.56 to 1.76 and 1.78 to 2.47 for THg and OHg, respectively. Overall, rates of mercury bioaccumulation were similar across sites with variations in biota Hg concentrations reflecting baseline differences in site environmental levels. Understanding mercury bioaccumulation and magnification in estuarine biota is critical to safeguard the multiple ecologic functions and economic benefits estuaries provide.

Catches of European hake (Merluccius merluccius) in the North Sea have increased substantially during the last decade, even though there is no directed commercial fishery of hake in this area. We analysed the spatial distributions of hake in the northern the parts of its range, (where it is less well-studied), using ICES international bottom trawl survey data from 1997 to 2015. We examine length-frequency distributions for (i) distinct modes enabling the assignment of fish into categories which likely corresponded to the ages 1, 2, and 3+ and (ii) patterns of seasonal spatial distribution for the different groups. Age categories 1 and 2 fish were most abundant in the northern North Sea, and appear to remain in the North Sea until 2 years of age, when they move into deeper waters. Their distribution has expanded into the western-central North Sea in the last decade. Age category 3+ fish were most abundant in the northern and central North Sea during summer, indicating a seasonal influx of large individuals into this area likely associated with spawning activity. The distribution of these older fish has gradually expanded westward in both seasons. [ABSTRACT FROM AUTHOR]

Abstract Europe's Blue Growth strategy promotes the intensification of human activities at sea and increases the environmental risk such as the decline of the provision of key ecosystem services and potential conflicts among human activities. The fishing sector, in the Alboran Sea, is economically and culturally one of the most important and relies on overexploited target species such as European hake (Merlucius merlucius). Here we identified and quantified the impact of human pressures on the capacity of marine habitats to support the provision of food as an important ecosystem service. We modelled the spatial distribution of nursery areas of European hake in the Alboran Sea, using General Additive Models (GAM) and overlaid those with European Nature Information System (EUNIS) habitats. A sensitivity analysis of hake nursery areas to cumulative human impacts identified the Bay of Malaga as the most sensitive area with trawling frequencies up to 60 times higher than the habitats recovery time. Further, we identified an increased conflict potential among human activities such as trawling and extraction with the presence of Marine Protected Areas (MPAs), which provide MPAs a high vulnerability similar to that found in unprotected areas. Future scenarios considering the increase of renewable energy and alternative food production show conflicts between aquaculture and MPAs as well as offshore wind farms and offshore shipping. Hence, our results show strong arguments for an integrated spatial management approach, including benthic trawling. We also suggest restricting trawling activities inside MPAs to safeguard the habitats capacity to support ecosystem services. Our spatially explicit assessment framework is transparent and transferable to other Mediterranean regions. Thus, it can function as a model on how to incorporate cumulative effect assessments in marine spatial planning processes. Highlights • Cumulative impact on Hake nursery area. • Benchmark of trawling impact by swept per recovery time index. • Present and future user conflicts in the Spanish contiguous zone.. • Incorporation of cumulative effect assessment in marine spatial planning processes. [ABSTRACT FROM AUTHOR]

The catfish Genidens barbus is a commercial species from South America. The aim of the present study was to examine the inter-annual variability in estuary-specific chemical signatures of otolith cores (Ba:Ca, Mg:Ca, Mn:Ca, Sr:Ca and Zn:Ca ratios) for three estuaries from Argentina and Brazil where adults were collected over multiple years. Secondarily, we evaluated whether the percentages of classification of individuals to their natal origin place are affected by the grouping of several cohorts. Most element:Ca ratios were not significantly different among year cohorts. Results from PERMANOVA revealed significant differences in the multi-element signatures of the otolith core between cohorts for the Plata River estuary (PR) (P = 0.006) and the Patos Lagoon (PL) (P = 0.03), while no significant differences (P = 0.9) were found for Paranaguá Bay (PB). The percentages of spatial classification (discriminant function analyses) decreased to between 15.5 and 25% for PR and PL when cohorts were grouped. This work makes it clear that the temporal variation in the chemical signature of the adult catfish otolith core can greatly affect the percentages of spatial classification. [ABSTRACT FROM AUTHOR]

This study produced the first data on population parameters for sicklefin lemon sharkNegaprion acutidensat the granitic Seychelles Islands, adding to a limited catalogue of species information. Juveniles at a site in the Curieuse Marine National Park were tagged over two periods, in 2014–2015 and 2015–2016, with measurements of length (precaudal, fork and total) and weight, sex, and state of the umbilical opening recorded. Recapture data were used to calculate growth rates and population size. Mean annual growth rate was 5.40 cm y–1. A mean size at birth of 62.5 cm TL is in line with previous assessments of the species. Population-size estimates were similar for the two sampling periods (comprising 311 and 255 individuals) and higher than anticipated. Movements to outside the lagoon were recorded for early ages, and this, combined with weight loss and a reduction in condition factor as displayed in several individuals, suggests that the study area alone could not support the large number of sharks pupped yearly. [ABSTRACT FROM PUBLISHER]

Stereo baited remote underwater video systems (stereo-BRUVs) are commonly used to assess fish assemblages and, more recently, to record the localised abundance and size of sharks. The present study investigated the occurrence and size of white sharks (Carcharodon carcharias) in the near-shore environment off Bennett's Beach, part of a known nursery area for the species in central New South Wales, Australia. Six stereo-BRUV units were deployed approximately fortnightly between August and December 2015 for periods of 5 h in depths of 7-14 m. Stereo-BRUVs successfully recorded 34 separate sightings of 22 individual white sharks. The highest number of individuals detected during a single day survey was eight. All C. carcharias observed on stereo-BRUVs were juveniles ranging in size from 1.50 to 2.46-m total length (mean ± s.e., 1.91 ± 0.05 m; n = 22). The time to first appearance ranged from 15 to 299 min (mean ± s.e., 148± 15 min). This study demonstrates that the use of stereo-BRUVs is a viable, non-destructive method to obtain estimates of the size and presence of white sharks, and may be useful in estimating relative abundance in near-shore environments where white sharks are known to frequent. [ABSTRACT FROM AUTHOR]

The shallow coastal zone is an essential nursery habitat for juvenile flatfish species such as sole ( Solea solea L.). The increased frequency of shoreface nourishments along the coast is likely to affect this nursery function by altering important habitat conditions, including sediment grain size. Sediment preference of juvenile sole (41–91 mm) was studied in a circular preference chamber in order to understand the relationship between grain size and sole distribution. The preference tests were carried out at 11 °C and 20 °C to reflect seasonal influences. The juveniles showed a significant preference for finer sediments. This preference was not length dependent (within the length range tested) nor affected by either temperatures. Juvenile sole have a small home range and are not expected to move in response to unfavourable conditions. As a result, habitat alterations may have consequences for juvenile survival and subsequently for recruitment to adult populations. It is therefore important to carefully consider nourishment grain size characteristics to safeguard suitable nursery habitats for juvenile sole. [ABSTRACT FROM AUTHOR]

In the Northeastern Pacific, immature white sharks ( Carcharodon carcharias ) have been recorded in the nearshore waters of the Southern California Bight (SCB), USA, along the Mexican coast off Baja California and throughout the Gulf of California, which makes them susceptible to incidental capture by coastal fisheries. While the SCB is considered a nursery area for white sharks, records of young-of-the-year white sharks (YOY) in Bahia Sebastian Vizcaino (BSV) off central Baja California suggest that this region could also be an important white shark nursery area, but a formal evaluation of the region’s habitat function is lacking. We analyzed incidental catch records of white sharks from the US-Mexico border to BSV and evaluated whether Heupel et al.’s (2007) criteria for the identification of shark nursery areas were met for BSV. We compiled a total of 390 white shark incidental catch records between 1999 and 2013 and compared incidental catch records from the region north of Bahia Sebastian Vizcaino (NBSV; an area not considered to be a nursery ground) with those for BSV. There was a significantly higher abundance of newborns and YOY in BSV than NBSV. White shark were caught consistently throughout the year within BSV; however, the majority (70.1%) were caught between May and September. Our results are consistent with the shark nursery area criteria proposed by Heupel et al. (2007), and indicate the region between BSV to the SCB may be an important migration corridor for YOY and juvenile white sharks. Future management and conservation efforts ought to consider BSV’s nursery habitat function. [ABSTRACT FROM AUTHOR]

Estuarine environments are known to provide important feeding, breeding, resting and nursery areas for a range of shark species, including some which are considered dangerous to humans. Juvenile white sharks (<3 m) are known to frequent inshore environments, particularly ocean beaches, but their presence in and use of estuaries and coastal embayments is unclear. Given that estuarine environments are often surrounded by highly populated areas, understanding how white sharks use these environments will not only assist with their conservation management, but also inform public safety policies. The use of estuarine environments by acoustic-tagged white sharks was investigated from 2009 to 2015 at Port Stephens, New South Wales and Corner Inlet, Victoria, both of which adjoin known nursery areas for the species. Juvenile white sharks were detected within both estuaries, with 20 individuals recorded within the Port Stephens estuary, including four on one day. Only one tagged shark was detected within Corner Inlet; however, monitoring effort and local tagging in the area was more restricted. Detections in Port Stephens were predominantly from October to January and peaked in November. This study demonstrates that the footprint of known nursery areas for white sharks in eastern Australia should be expanded to include their adjacent estuarine environments. Consequently, there is clear potential for them to be exposed to a range of anthropogenic estuarine impacts, and that human interactions are more likely over warmer periods (summer), when human use of such waterways is more prevalent. [ABSTRACT FROM AUTHOR]

Many coral reef fish species use mangrove and seagrass beds as nursery areas. However, in certain regions, the absence or scarcity of such habitats suggests that juvenile coral reef fish may be seeking refuge elsewhere. The underlying biogenic substratum of most coral reefs is structurally complex and provides many types of refuge. However, on young or subtropical coral reefs, species may be more reliant on the living coral layer as nursery areas. Such is the case on the high-latitude coral reefs of South Africa where the coral communities consist of a thin veneer of coral overlaying late Pleistocene bedrock. Thus, the morphology of coral species may be a major determinant in the availability of refuge space. Acropora austera is a branching species that forms large patches with high structural complexity. Associated with these patches is a diverse community of fish species, particularly juveniles. Over the past decade, several large (>100 m) A. austera patches at Sodwana Bay have been diminishing for unknown reasons and there is little evidence of their replacement or regrowth. Seven patches of A. austera (AP) and non- A. austera (NAP) were selected and monitored for 12 months using visual surveys to investigate the importance of AP as refugia and nursery areas. There were significant differences in fish communities between AP and NAP habitats. In total, 110 species were recorded within the patches compared to 101 species outside the patches. Labrids and pomacentrids were the dominant species in the AP habitats, while juvenile scarids, acanthurids, chaetodons and serranids were also abundant. The diversity and abundance of fish species increased significantly with AP size. As the most structurally complex coral species on the reefs, the loss of APs may have significant implications for the recruitment and survival of certain fish species. [ABSTRACT FROM AUTHOR]

Effective species conservation requires the protection of all stages of its life-cycle. The Shark Reef Marine Reserve (SRMR) in Fiji is a marine protected area where large numbers of adult bull sharks (Carcharhinus leucas) congregate due to food provisioning. At the end of a calendar year bull sharks leave the area for reproductive activity, but parturition sites are still unknown. Between February 2014 and January 2015, we interviewed local fishermen and conducted a fishing survey, so as to assess presence and abundance of bull sharks in the Navua River near the SRMR. In total 84% of fishermen reported either seeing or catching sharks up to 8 kmupriver from the river mouth. They described them as small sharks having a rounded snout and being grey-brown in colour with a white belly, morphological characteristics that match juvenile bull sharks. During the fishing survey, a total of nine juvenile bull sharks were captured, including two that were recaptured after 108 and 92 days at liberty. Our findings confirmed the presence of bull sharks in the Navua River and provide a preliminary characterisation of a potential shark parturition or nursery area from a data-poor region. [ABSTRACT FROM AUTHOR]

Understanding of the spatial distribution and habitat use in different stages of a life cycle represents the essential aspect of threatened species management and conservation. In the present paper, the spatial and temporal patterns of habitat use in juvenile and adult life stages of the long-snouted seahorse Hippocampus guttulatus in the Mar Piccolo of Taranto (Apulia-Italy) (40°28′N, 17°16′W) were examined. From October 2012 to January 2014, monthly visual censuses were conducted in six coastal habitats of a focal area (Buffoluto site). Of a total of 317 individuals of the long-snouted seahorse that were sighted, 148 were juveniles, 82 adult females and 87 adult males. Our results showed significant differences in the habitat use between adult and juvenile life stages of H. guttulatus. Adult individuals were mainly concentrated within Cladophora prolifera beds and the wood poles of a mussel farm at 2-4 m of depth, while juvenile individuals were mainly present in shallower water (0.4-1 m) on artificial hard substrates covered by a brown algae turf. Assessing and describing the habitat use within different life stages of H. guttulatus represent a useful tool to support species conservation by protecting the habitats it uses. [ABSTRACT FROM AUTHOR]

Mangroves are recognised as important nursery and feeding areas for resident and inshore fish species. However, the importance of West African mangroves to the life cycle of fish communities remains poorly studied. The present study is the first record of fish species in tropical insular mangroves for this region and its aim was to assess habitat usage by fish species. Two mangroves of São Tomé Island (Praia das Conchas and Malanza) were sampled with a multihabitat approach and using different fishing gear to maximise the diversity of fish species collected. Several environmental parameters were also measured. Both mangroves are nursery and opportunistic feeding grounds for fish species, as well as settlement areas for resident species. The highest number of both juveniles and adults (inshore and residents) was observed at the Malanza mangrove, which is also the largest and has the highest habitat heterogeneity. Four new occurrences were reported for the São Tomé and Principe area, namely Pomadasys jubelini, Bostrychus africanus, Dalophis cephalopeltis and the introduced species Oreochromis mossambicus. [ABSTRACT FROM AUTHOR]

The smooth hammerhead shark, Sphyrna zygaena, occurs in warm temperate waters around the northern North Island of New Zealand. Commercial fishing records and research trawl survey data were used to determine their distribution. Highest catch rates were recorded in relatively sheltered bays and coastlines along the northeast coast of North Island. Neonate and juvenile sharks use shallow coastal waters and large harbours and estuaries as nursery areas up to an age of two years and total length of 150 cm. Five sharks were electronically tagged but two apparently died and three (137-160 cm total length) returned useful data. Two tagged sharks remained in or near the Bay of Islands for 6-55 days after tagging, moving extensively through the bay. A third shark moved about 155 km southeast in 250 days. That shark spent 70 days mostly shallower than 10 m (94% of time) with occasional dives to 40 m. Thereafter, it oscillated between the surface and depths of 60-80 m, with most time (55%) being spent at 40-60 m. Maximum recorded depth was 144 m. [ABSTRACT FROM AUTHOR]

Trophic interactions play a key role in nursery habitats, and by affecting growth and condition of the juveniles, may control the quality of a given estuarine nursery. This study investigated the trophic ecology of flounder (Platichthys flesus) and common sole (Solea solea) juveniles in the Lima estuary nursery. Feeding location, main organic matter sources, and prey of the target species were assessed by carbon (δ13C) and nitrogen (δ15N) stable isotopes, as well as by stomach content analysis. The juveniles, macroinvertebrates, and sediment and water column samples were collected in August 2014 in the lower, middle and upper sections of the Lima estuary. The diet of 0+ flounder relied upon prey from the upper estuary (salinity >5), namely Chironomid larvae and Corophium spp. which showed the role of the upper estuary prey to the 0+ flounder diet and suggest the relative site fidelity of the young juveniles. In contrast, 1+ flounder juveniles had a diverse diet based on bivalves, polychaetes and crustaceans, and a variable stable isotope signature indicating they fed in different areas along the estuary. The 1+ sole juveniles also fed on polychaetes, crustaceans, and bivalves, but the stable isotope values suggested a dependence on the lower estuary (salinity >30) and marine food web sources. Such differential use of food may be understood as a strategic approach to reduce intra- and interspecific competition and thus ensuring the use of Lima estuary as nursery area for these two flatfish species.

Estuarine tapertail anchovy Coilia nasus is a small-sized anadromous species in the Yangtze River, China. It is probably the most expensive fish in the world with price as high as $1000/kg and even $9600 for a single extremely large individual with a total length of 45.3 cm and body weight of 0.325 kg in the Jiangsu section of the river in 2012. However, when and where C. nasus spawn along the Yangtze River has still remained a mystery so far. In our field surveys of 2014 and 2015, some highly mature female and male C. nasus with stage V or VI gonads were firstly collected in the water region around Xingzi County in the Poyang Lake, which is nearly 1000 km away from the mouth of the Yangtze River. Although previous studies believed that all C. nasus in the Poyang Lake were freshwater residents, the otolith microchemistry signatures of the present study determined with EPMA and LA-ICPMS further clearly demonstrated that these fish were anadromous individuals. The findings indicated that the C. nasus migrated over nearly 1000 km upstream, with an extremely strong migration ability, passing through the lower reaches of the Yangtze River from the adjacent Yellow sea (even from the areas nearly straight line for as far as ca. 300 km off the Chinese coast line) or East China Sea (Figure 1). The aforementioned evidence strongly suggests that the water region around Xingzi County in the Poyang Lake is a possible spawning/nursery area for anadromous C. nasus. It will be critical to ensure the protection of this region of the Poyang Lake being free from the environmental destruction of anthropogenic activities, especially hydraulic structure (especially dam) construction and sand mining.

Migrating humpback whales from northern and southern feeding grounds come to the tropical waters near Osa Peninsula, Pacific of Costa Rica, to reproduce and raise their calves. Planning effective marine protected areas that encompass humpback critical habitats require data about which oceanographic features influence distribution during the breeding period. This study examines the relationship between water depth and ocean floor slope with humpback whale distribution, based on sightings during two breeding seasons (2005 and 2006). Data are from the Southern and Northern subpopulations in the Eastern Tropical Pacific (ETP). Analysis followed the basic principles of the Ecological Niche Factors Analysis (ENFA), where indices of Marginality and Tolerance provide insights on the restrictiveness of habitat use. At a fine scale, physical factors such as water depth and slope define the critical breeding and nursing habitat for M. novaeangliae. Divergence in the subsamples means of depths and slope distribution, with the global mean of the study area in both eco-geographical variables, determine habitat requirements restricted by topographic features such as depths (< 100 m) and slope (< 10%), and locate the key breeding and nursing habitat of the species within the continental shelf domains. Proposed Marine Protected Areas (MPA’s) network plans should consider connectivity of Caño island-Drake Bay and the extension of Corcovado National Park maritime borders. Rev. Biol. Trop. 56 (2): 591-602. Epub 2008 June 30.Las ballenas jorobadas viajan a aguas tropicales para reproducirse y criar a sus ballenatos. Es importante entender las características oceanográficas que influencian su distribución para lograr una planificación efectiva de áreas marinas protegidas con hábitats críticos para estos cetáceos. Este estudio examina la relación entre la profundidad, la pendiente del suelo oceánico y la distribución de estas ballenas, usando avistamientos del 2005 y 2006 en la costa Pacífica de la Península de Osa, Costa Rica (temporada de reproducción del sur y norte en el Pacífico Tropical Oriental). Usamos Análisis de Factores de Nicho Ecológico (ENFA por sus siglas en inglés), donde los índices de Marginalidad y Tolerancia ilustran las restricciones en uso de hábitat. En una escala local, factores físicos como la profundidad y la pendiente definen el hábitat crítico de reproducción y cría de M. novaeangliae. Las divergencias entre las medias de las sub-muestras y la media global del área de estudio en ambas variables eco-geográficas, determinan las limitaciones en requerimientos de hábitat en aspectos topográficos como la profundidad (>100 m) y la pendiente del fondo (>10%), localizando los hábitat críticos para reproducción y cría dentro de la plataforma continental. Los planes y propuestas para un sistema de áreas marinas protegidas deben de considerar la conectividad de la isla del Caño y la Bahía de Drake, así como la extensión de los límites marinos del Parque Nacional Corcovado.

Habitat connectivity in coral-reef ecosystems partly depends on fish movements, and considerable effort has been made to understand their temporal and spatial patterns of habitat use. In the Caribbean, the schoolmaster, Lutjanus apodus , typically settle and grow up in mangroves and seagrass beds, migrating later to coral reefs. However, direct settlement on reefs, or permanent stay in mangroves, has also been observed in some localities, raising the question of whether schoolmasters could exhibit a wider repertoire of conditional, context-specific strategies. We investigated this issue in a new region, i.e., the Mesoamerican Reef System, based on parasite tagging. A total of 220 juvenile schoolmasters 1–2 yr old collected in estuarine mangroves, estuary sandy flats with marine influence, and reefs, in the region of Chetumal Bay were examined for metazoan parasites. This parasite fauna (36 taxa) significantly changed along the estuarine-marine gradient. The long-lived larvae of Contracaecum sp. type 2, Gorgorhynchoides bullocki , and Neoterranova sp. recruited very frequently in fish from estuarine mangroves. Infection patterns of these parasites suggested that (i) the fish collected in mangroves had settled and lived there until collection (1–2 years); (ii) the infected fish collected in sandy flats and reefs (a minimum of ca. 20% of the sample) had an estuarine origin. The digenean Hamacreadium mutabile had a clear marine affiliation and was never collected in estuarine fish. This suggests that 'marine' schoolmasters had not performed commuting excursions to estuarine waters, at least within the last months prior to collection. The small size of some fish infected with H. mutabile conforms to a direct settlement on reefs. In summary, the parasitological evidence provides mixed evidence of both habitat migration and residency of schoolmasters, also illustrating the potential of parasites to unveil patterns of habitat use by coral-reef fishes. • The use of parasite tagging to monitor coral fish movements is proposed, taking the schoolmaster as a model. • Out of 36 parasite taxa found, 3 were selected as key habitat markers. • The digenean Hamacreadium mutabile had a clear marine affiliation and was never collected in estuarine fish. • Fish in mangroves settled and lived there during 1–2 years, and those in sandy flats and reefs had an estuarine origin. • Parasite tagging can offer useful complementary mixed evidence of both habitat migration and residency of schoolmasters. [ABSTRACT FROM AUTHOR]

Otolith Sr:Ca ratios were used to evaluate the contribution of estuarine nursery areas to the temperate seabass ( Lateolabrax japonicus) population in Tango Bay, the Sea of Japan. Otolith Sr:Ca ratios of juveniles collected from freshwater, brackish and coastal areas were analysed to determine a criterion for distinguishing whether individuals used estuarine or coastal areas as nurseries. Otolith Sr:Ca ratios of adult seabass collected around Tango Bay were also analysed to detect the records of salinity that juveniles experienced and to estimate the contribution of each habitat. Sr:Ca ratios of the edges of otoliths of juveniles from freshwater areas were 2.4 × 10−3 in average, which were significantly lower than those of juveniles collected from a coastal area (4.9 × 10−3 in average) owing to differences in salinity conditions among these areas. Based on the threshold criterion determined by this difference, 39 out of 107 (36%) adult seabass were estimated to have used the estuary as a nursery during their juvenile stage according to their Sr:Ca chronologies. Despite the small area covered by estuarine nurseries compared with coastal waters, the Yura River estuary contributed considerably to the adult seabass population. This indicates estuaries play an important role as nurseries for seabass juveniles, and it should be noted that the estuaries are important nurseries to conserve the stocks of coastal fishes. [ABSTRACT FROM AUTHOR]

The feeding ecology of juvenile temperate seabass ( Lateolabrax japonicus) in relation to various prey environments was analyzed in the Yura River estuary from 2008 to 2012. Juveniles mainly fed on copepods and mysids, both in the Yura River estuary and in the adjacent coastal area. The dependency on the mysids increased as juveniles grew from 15 to 25 mm standard length (SL), and the main stomach contents were mysids for juveniles larger than 25 mm SL. The maximum size of food contents increased from 2 to 15 mm with the growth of juveniles from 15 to 25 mm SL. Most prey items smaller and larger than 2 mm were composed of copepods and mysids, respectively. The mean size of ingested food items increased with the size of the juveniles, while the mean number of prey items in each stomach decreased with growth after juveniles reached 22 mm SL. As a result, the stomach content index increased with the size of juveniles. These results indicate that the shift to larger-sized prey items (from copepods to mysids) is important for juveniles to obtain energy efficiently. Mysids were larger and more abundant in the estuaries than those in the coastal area. Therefore, the estuary provided better foraging conditions to juvenile temperate seabass than the coastal area. [ABSTRACT FROM AUTHOR]

Background: Shallow nearshore marine ecosystems are changing at an increasing rate due to a range of human activities such as urbanisation and commercial development. The growing numbers of constructions and other physical and structural alterations of the shoreline often take place in nursery and spawning habitats of many fish and other aquatic species. Several coastal fish populations have seen marked declines in abundance and diversity during the past two decades. A systematic review on the topic would clarify if anthropogenic physical and structural changes of near-shore areas have effects on fish recruitment and which these effects are. Methods: The review will examine how various physical and structural anthropogenic changes of nearshore fish habitats affect fish recruitment. Relevant studies include small- and large-scale field studies in marine and brackish systems or large lakes in temperate regions of the Northern and Southern hemispheres. Relevant studies may be based on comparisons between undisturbed and disturbed areas, before and after disturbance, or both. Relevant outcomes include measures of recruitment defined as abundance of juveniles of nearshore fish communities. Searches will be made for peer-reviewed and grey literature in English, Dutch, Danish, Finnish, German, Swedish and Spanish. All fish species and species groups will be considered in this review. Included relevant studies will be subject to a critical appraisal that will assess study validity. From relevant included studies, we will extract information on study characteristics, measured outcomes, exposure, comparators, effect modifiers and critical appraisal. Data synthesis will contain narrative and summary findings of each included study of sufficient quality. Meta-analysis may be possible in cases where studies report similar types of outcomes. [ABSTRACT FROM AUTHOR]

Annual spatial distribution and relative abundance of age-2 and age-3 northern rock sole (Lepidopsetta polyxystra) and summer bottom temperatures were analysed using data from eastern Bering Sea summer trawl surveys from 1982 through 2012. Previously observed differences in age-0 northern rock sole distribution persisted until age-2 and age-3. Latitudinal distributions of age-2 and age-3 fish were correlated most strongly with summer bottom temperatures 2 and 3 years prior to the survey year, during the time that the fish would have been age-0. Thus, temperature during the age-0 year may affect spatial distribution for the first few years of life. Distribution of age-2 and age-3 fish shifted northwards 2 years after the beginning of a warming trend from 1999 to 2003, and shifted southwards 2 years after a cooling trend from 2004 through 2010. Northerly distributions were correlated with high abundances. Density dependence was ruled out as a reason for northward shifts in distribution given a lack of correlation between latitudinal distributions and the annual abundances within the southern part of the distribution. We propose that the large northern nursery area produces large cohorts of northern rock sole, and that bottom temperatures in the age-0 year affect use of the northern nursery area. [ABSTRACT FROM AUTHOR]

Background: Determining the habitat use of mobile marine species is important for understanding responses to climate change and aids the implementation of management and conservation measures. Inference of preferred habitat use has been greatly improved by combining satellite-based oceanographic data with animal tracking techniques. Although there have been several satellite-tracking studies on ocean sunfish Mola mola, limited information is available about either horizontal or vertical environmental preferences. In this study, both geographical movements and diving behaviour of ocean sunfish were explored together with the environmental factors influencing this species' space use in the north-east Atlantic. Results: Habitat selection of electronic-tagged sunfish (n = 22 individuals; 0.6-1.4 m total length, TL) was investigated using geolocations from Argos-linked and pop-up satellite archival transmitters. Satellite tracking (up to 171 days, mean 66 days) revealed seasonal movements: northward in spring-summer and southward in cooler months. Sunfish spent extended periods in three focal areas, the Gulf of Cadiz, north-east Iberia and the Alboran gyre, which are characterised by the presence of frontal features with elevated primary production. Habitat modelling revealed that sea surface temperature and thermal gradients significantly influenced sunfish distribution. Diving profiles, extending from the surface to a maximum depth of 704 m, revealed different depth-use patterns not linked to geographical region or water column stratification. Overall, a size-related movement pattern was detected with larger individuals (>0.92 m TL) travelling further, exploiting greater depth ranges and spending more time at depth than smaller fish. Conclusions: Ocean sunfish in the north-east Atlantic displayed seasonal movements, primarily driven by thermal preferences, extending into higher latitudes in summer. Moreover, fish also occupied productive frontal areas for long periods, presumably for improved foraging opportunities. Lastly, sunfish showed considerable variability in diving patterns which likely reflect the tracking of planktonic prey distributions. [ABSTRACT FROM AUTHOR]