Brook trout Salvelinus fontinalis is a popular sportfish native to North America and introduced worldwide, as well as an indicator of environmental quality. We review published studies and synthesize a view of how geomorphological, climatological, and ecological factors gave rise to the current distribution of brook trout and the geographic patterning of its population genetic diversity. Phylogenetic studies show that the center of diversity for charrs – i.e., members of Genus Salvelinus – is east Asia and northwestern North America and that divergence of most Salvelinus species occurred during the Miocene Epoch. Members of the Salvelinus lineage dispersed throughout northern Canada and eastern North America, the contemporary natural distribution of brook trout, perhaps with the opening of the Bering Strait at ~5.3 mya near the end of the Miocene Epoch or perhaps earlier through the Paleo-Bell River system. The contemporary population genetic structure of brook trout was patterned by retreat to refugia from Pleistocene glaciation, followed by Holocene recolonization of eastern North America. That is, contemporary populations of brook trout represent the descendants of fish from Acadian, Mid-Atlantic, or Mississippian refugia and from recent mixing upon secondary contact. Population genetic variation mostly conforms to watershed boundaries, a finding that informs fisheries and conservation management strategies. A growing body of research provides insights into local adaption of brook trout populations. The future viability of many populatons of brook trout will depend upon implementation of well-considered, conservation-oriented management actions.

Landscape genetics has emerged as a useful approach for inferring how environmental changes impact genetic variation and population structure within species. Brycon insignis, commonly known as piabanha or Tiete tetra, is a fish species endemic to the Para & iacute;ba do Sul basin in southeastern Brazil. Unfortunately, its population has declined over recent decades, and it is currently listed as Endangered in red books maintained by Brazil and the IUCN. We assessed the current genetic diversity of the four remaining populations of B. insignis in the region using microsatellite DNA loci and compared this to results of an assessment conducted over a decade ago. Our goal was to evaluate the current genetic status of these wild populations and assess how environmental changes relate to changes in genetic diversity over time. The respective populations remain notably distinct genetically (D EST = 0.34, F ST = 0.07), and comparison of results from 2009 and the present shows significant loss of genetic diversity within populations. The genetic structuring observed in the B. insignis populations may be attributable to environmental changes and demographic isolation. Additionally, decreased genetic variation may jeopardize the long-term viability of the isolated populations, in turn threatening the viability of the species. Our findings examined the effects of ongoing habitat degradation within the context of existing riverscape fragmentation and highlighted the loss of genetic diversity as a key response variable in landscape genetic models.

Nest association is a putatively mutualistic mode of reproduction utilized by many fishes of the North American freshwater family Leuciscidae. It is defined by the interaction between one 'host' species that builds and maintains a nest, and multiple other species of 'nest associates' that spawn upon it. We studied the aggregations of spawning Nocomis leptocephalus in order to identify potential embryo predation behaviors of the host or associates. We investigated the effectiveness of host parental care by comparing predation upon buried and unburied embryos. The main observed parental care behavior of the host-embryo burying-increased embryo survival by 26.8 (+/- 5.6%) on average, indicating that it is an effective method of improving reproductive success. We hypothesized that both host and associates are responsible in part for embryo predation, and that nest associate abundance increased the risk of embryo predation. DNA metabarcoding of gut contents revealed that indeed both host and associates consumed heterospecific embryonic material, whereas model-based evidence suggested that associate abundance only weakly affected embryo predation rate. This work furthers and supports previous research recognizing the nuance in identifying nest association as a mutualism, and work which has suggested the host benefits from nest associates beyond the predation-dilution effect on its embryos. Here we identify an additional benefit to hosts and associates-the direct consumption of each other's embryos-making this the first study to directly investigate and demonstrate predation upon embryos by nesting fishes in this system.

Mutualisms are complex, interspecific relationships, which sometimes create "selfish-herds" as individuals of each species compete to maximize their own fitness. Nest association, where individuals of different species spawn on a nest created by a host species, is a reproductive interaction characteristic of some minnows (Leuciscidae) and is considered mutualistic despite mimicking the behavior labeled "brood parasitism." We studied the spawning behaviors of bluehead chub (Nocomis leptocephalus) and its nest associates, testing the hypothesis that bluehead chub exploits the selfish-herd dynamic in a novel manner by arranging embryos within its nest to maximize the survival of its own offspring at the expense of the nest associates' offspring. Our results show that embryos were not uniformly distributed within a nest, as one section representing one-sixth of the nest's total volume contained a disproportionate percentage of embryos (x¯ = 40.0% ± 6.1% SE). We found three-quarters of host embryos within deeper nest sections safer from embryo predators, whereas only a third of all associate embryos were found in the same sections. These results support our hypothesis that male Nocomis leptocephalus create "embryonic selfish-herds" within their nests. This is the first study to document the existence of embryonic selfish-herds, a phenomenon that warrants the reexamination of some vertebrate reproductive interactions labeled as brood parasitism.

Freshwater mussels in the genera Fusconaia, Pleurobema, and Pleuronaia are similar in their external shell morphology, which has made the identification and classification of species within these genera difficult and led to many taxonomic revisions. Large samples (N = 464) of select mussel species in these genera were collected from 2012 through 2014, primarily in the upper Tennessee River basin of Tennessee and Virginia, USA. Mitochondrial ND1 and nuclear ITS1 DNA sequences were analyzed to assess phylogenetic relationships among taxa. Ten species were verified as phylogenetically distinct at ND1, two of which were cryptic and previously unrecognized species. Described herein as Pleurobema parmaleei and Pleuronaia estabrookianus, each species clade was diverged at this gene region by ~3.0% from the respective closest congener. The nuclear ITS1 gene region’s nucleotide-site insertion/deletion (indel) patterns were analyzed as single mutational events rather than as fifth character states or missing data. Most species, including these two, were phylogenetically distinct at the ITS1 region when incorporating indels into analyses, but some estimated interspecific pairwise distances were lower than corresponding intraspecific estimates. Among morphological traits assessed for each species, differences in foot color and gravidity characteristics illustrated differences between phylogenetically recognized species and their closest congeners. Due to the limited known geographical distributions of these two cryptic species, each may require protection under the U.S. Endangered Species Act. While this study collected large sample sizes for each species, many streams in the basin remain unsampled and could potentially contain populations of these species or additional cryptic species.

Aerobic denitrification, a novel method for complete nitrate removal process, relies on a constant carbon supply, and carbon availability can be a limiting factor for the process. Three biodegradable polymers - polybutylene succinate (PBS), polycaprolactone (PCL), and polylactic acid (PLA) were used as carbon source of aerobic denitrifying bacteria, Halomonas venusta for treating recirculating aquaculture wastewater in batch tests, respectively. The group utilizing PCL displayed the greatest efficiency in nitrate removal. Afterwards, a continuous flow airlift fluidized bed (CAFB) - aerobic denitrification bioreactor using PCL(PADR) as bio-carriers and carbon source was started up. The effect of shifting temperature on the nitrate removal and microbial community of CAFB-PADR was investigated under different hydraulic retention times (HRT). The results showed that no significant difference was detected in denitrification activity at 25 and 30 degrees C condition, where the denitrification rate was 1.1-1.8 times higher than that at 15 degrees C. However, the nitrogen removal efficiency was above 50 % and there was barely accumulation of nitrite at 15 degrees C, indicating the good nitrate removal performance in CAFB-PADR at all three temperature conditions. Microbial composition analyses revealed that as the temperature decreased, the relative abundance of Gammaproteobacteria increased, while those of Alphaproteobacteria and Bacteroidia diminished decreased. The existence of denitrifying function genera (Marinobacter, Pseudomonas, Halomonas and Hydrogenophaga) ensured the rapid removal of nitrogen in the biofilter. When the temperature dropped to 15 degrees C, Pseudomonas progressively took the position of Marinobacter, both of which had denitrification and degradation activities. The relative abundance of the denitrifying bacteria Halomonas that we inoculated has been less than 1 % since phase II. Overall, the PCL-supported CAFB-PADR demonstrated in this study shows potential for removing high concentrations of nitrate from recirculating marine aquaculture wastewater.

We quantified morphological variation among genetically identified specimens of Fusconaia flava, F. subrotunda, Pleurobema cordatum, P. plenum, P. sintoxia, and P. rubrum inhabiting the Green River, Kentucky, species with shells that are morphologically similar to each other and thus difficult to identify. Molecular identifications then were compared with phenotype-based identifications by experts, who on average correctly identified 70% of the specimens. Expert identification of the putative species P. rubrum and P. sintoxia resulted in them usually being identified as the latter. Multi-variable decision tree analysis was conducted to determine the best suite of morphological variables for identifying live mussels and shells to species. Cross-validation error rates for these analyses were 12.6% and 4.14% for live mussels and shells, respectively. Both random forest and decision tree analyses showed the most important variables to be the presence/absence of a sulcus and shell shape (trapezoidal, circular, oval, equilateral triangle, or isosceles triangle). Dichotomous keys for identifying shells and live mussels were developed based on key morphological characteristics readily identifiable in the field, including foot color, beak direction, and beak position relative to the anterior margin. However, a definitive identification of these species may still need to rely on molecular methods, especially for endangered species.

Objective Horseshoe crabs Limulus polyphemus play a vital role in the Delaware Bay ecosystem. The migratory stopover of several shorebird species occurs during the horseshoe crab spawning season, and the eggs of horseshoe crabs provide an essential food source to fuel their northward migration to breeding areas. High commercial fishery use of horseshoe crabs as bait during the 1990s coincided with a decline in crabs and shorebirds, particularly the red knot Calidris canutus rufa, which has been listed as threatened under the U.S. Endangered Species Act since 2015. In response to the population decline of shorebirds, the Atlantic States Marine Fisheries Commission began reducing the harvest of horseshoe crabs in 2000 with a goal of rebuilding the population of horseshoe crabs and shorebirds that depend upon them. The objective of this analysis was to determine whether horseshoe crab harvest management in the Delaware Bay region has increased the abundance of the species in recent years.Methods We analyzed data from fisheries-independent trawl surveys of horseshoe crab relative abundance using a Bayesian hierarchical model to determine whether harvest management has resulted in the rebuilding of the horseshoe crab population to levels seen in 1990-a period before the overuse of horseshoe crabs and the decline in the population of red knots.Results Data from multiple surveys showed that the horseshoe crab population in Delaware Bay declined from the 1990s through approximately 2005, was relatively low and stable until 2010, and then increased through 2023, with a 0.38 probability of exceeding the 1990 level.Conclusions The results of this analysis support the effectiveness of management decisions related to horseshoe crabs in the Delaware Bay region. In response to harvest restrictions, the abundance of horseshoe crabs has neared levels observed in the early 1990s-a period prior to high commercial use and a decline in both horseshoe crabs and shorebirds that depend on them for food during annual migrations. This study examined multiple horseshoe crab abundance indices and determined that the population has increased following harvest restrictions implemented in the early 2000s. By 2023, the population neared abundance levels estimated in 1990.

Trachurus trecae , commonly called the Cunene horse mackerel, is a crucial fishery resource distributed along the eastern Atlantic coastline from Morocco to Angola. Angolan fishers frequently catch this species, which is highly valued. In 2010 and 2017, scientists collected T. trecae specimens from three regions of the Angolan coast (Cabinda: North - Luanda: Center - Benguela: South) to conduct genetic analysis using microsatellites specifically designed for this species. The objective was to evaluate the genetic diversity within and among regions within and among years. The results show that the mean allelic richness values in the 2010 and 2017 collections were 11.87 and 11.30, respectively. The LynchRd Point Estimator of Parentage (EPP) estimated 27%, 33%, 20% and 23% inbreeding for the Northern, the Center, the Southern, and for the temporal South 2017 samples, respectively. The effective population size (N-e) was estimated to be 343.2 in 2010 and 685.2 in 2017. No recent bottleneck effect was detected within either collection period. Analyses of multilocus genotype frequencies using both DAPC and STRUCTURE revealed that the 2010 samples contained three genetic clusters. The collection from the Center site was genetically less related to the North and South ( R-ST =0.0265; D-EST = 0.1695, p <0.05) than the latter were to one another. We found no significant genetic differentiation between the temporal sets of samples (Phi(CT) = 0.0076 , p = 0.49), indicating temporal genetic stability of T. trecae on the Angolan Coast over seven years. Our results identified local stock structure, which informs management and conservation of the fishery.

Walleye is an important sportfish across eastern North America, is commercially fished in the Laurentian Great Lakes region, and has been introduced outside its native range. Thirty-eight Walleye populations within six watersheds across the Eastern Highlands and other portions of the native range were screened at eight microsatellite DNA loci to better understand evolutionary history and to inform fishery management and conservation efforts. Population genetic variation showed divergent assemblages of populations, respectively, living in the Mobile Bay, Mississippi River, Eastern Highlands (Tennessee, New, and Ohio Rivers), and Great Lakes drainages today. All estimates of effective numbers of breeding individuals were under 25, and all populations within all watersheds had ~15–20% inter-individual relatedness, likely attributable to the effects of both natural demographic processes and stocking. The extent of Eastern Highlands Walleye includes both the Ohio and Tennessee River basins.

Here, we report a new locality for a subterranean species of Garra in the Zagros Mountains of Iran. The mitochondrial DNA of fish from this locality is closely related to that of G. typhlops, but genomic data and presence of a mental disc are indicative of a possibly hybrid origin for the analyzed individual. Based on the genetic relationships among the Iranian subterranean Garra species and Eidinemacheilus smithi from different habitats, we infer that their respective karst habitats are isolated and might have been colonized by surface-dwelling ancestors independently. Based on the inferences made in this study, we suggest that subterranean fishes of Iran are mostly composed of small, local populations, a factor which must be considered in conservation planning.

Fish migrate for varied reasons, including to avoid predators and to access feeding, spawning, and nursery habitats, behaviors that enhance their survival and reproductive rates. However, the migratory ecology of many important fishes, especially those in river–floodplain ecosystems, remains poorly understood. One fish of the Amazon Basin whose migratory behavior is poorly understood is the catfish Pseudoplatystoma fasciatum. Here, we used otolith elemental microchemistry to characterize the migration ecology of P. fasciatum in the Amazon Basin. The main research questions of this study were: (1) does P. fasciatum move between waters with different Sr isotopic signatures (87Sr/86Sr) and chemical compositions? (2) What distance do they migrate? (3) Is the migration of P. fasciatum related to age? And (4) does P. fasciatum migrate mainly upstream, downstream, or in both directions? We assessed whether P. fasciatum migrates between waters with different 87Sr/86Sr values, comparing the Sr isotopic signature of otolith transects of each individual with the range of Sr isotopic signatures within the respective rivers. We found that 34% of the 71 fish analyzed migrated between rivers with different Sr isotopic signatures and 66% did not. The mean migration distance migrated was 126 km, with most specimens migrating between 72 and 237 km. Apparently, no fish of age one or age six or older migrated. All fish that migrated were between two and five years of age, with 20% of the specimens that migrated being two years old, 40% three years old, 30% four years old, and 20% five years old. Sixty-six percent of all individuals that migrated between rivers with different Sr signatures did so bidirectionally, while 33% moved unidirectionally. According to our definition of homing behavior in which fish migrated back to the same river where they were born, 41% of all fish that migrated displayed apparent homing behavior. Our findings provide insights into the migratory ecology of P. fasciatum, corroborating and refining knowledge reported in the literature. Our results on the migratory ecology of P. fasciatum have implications for sustainable fisheries conservation and management: conserving P. fasciatum requires habitat maintenance and suitable fishing practices in spawning and nursery habitats, and managers must consider large geographic areas for effective fishery management and conservation.

Fish growth is a fundamental biological process driven by a multitude of intrinsic (within-individual) and extrinsic (environmental) factors that underpin individual fitness and population dynamics. Interannual variability in river hydrology regarding the intensity and duration of floods and droughts can induce interannual variations in the biotic and abiotic variables that regulate fish growth. However, the understanding of how interannual variability in river hydrology affects fish growth remains limited for most species and ecosystems. We evaluated how inter-annual hydrological variations within the Amazon River basin influence the growth of the catfish Pseudoplaystoma fasciatum. Our research questions were as follows: Do floods lead to the faster growth of P. fasciatum and droughts lead to the slower growth? And do floods and droughts affect all age classes in the same manner? We sampled 364 specimens of P. fasciatum from five sites in the Amazon basin, estimated their growth rates, and related the growth rates to indices of the intensity of floods and droughts. We fitted linear mixed-effects models to test the relationship between growth increments and hydrological indices (with F and D quantifying the intensities of floods and droughts, respectively), age as fixed effects, and basins and Fish ID as random effects. We found an inverse relationship between the increment width in the fish hard parts and hydrological indices. That is, intense floods and droughts negatively affected the growth rates. We also found that the growth of P. fasciatum was no different in years with intense and mild floods across age classes 1–5, although was different for age class 6. However, the growth of P. fasciatum was faster in years of mild droughts for all age classes. Our results showing that the growth of P. fasciatum was slower in years of intense droughts are supported by those of previous studies in the Amazon basin and elsewhere. However, our results showing for the first time that the growth of P. fasciatum is slower in years of intense flooding is the opposite of patterns found in other studies. These results thus suggest that the growth of P. fasciatum is maximized within an optimum range of hydrological conditions, where neither floods nor droughts are intense.

Animal biotechnologies have the potential to improve the sustainability and security of our global food systems. Government regulatory authorities are responsible for ensuring the safety of food their citizens consume, whether it is produced via conventional breeding methods or biotechnologies. While some countries have implemented animal biotechnology oversight policies, many countries have yet to develop theirs. Historically, regulatory approvals were required before products of biotechnology could enter the marketplace, and the high cost of the approval process limited the number and types of animal and plant products that sought approval. Only one biotech animal in the world that was developed for food production has reached the market under a GMO or rDNA approval process. The advent of genome editing techniques has revolutionized the scientific approach to introducing changes into DNA sequences and how biotechnology can be used to enhance agricultural breeding. Regulatory dialogs about biotechnology also have changed as a result of these new technologies. Regulatory agencies have begun to respond to these scientific advances, and a growing number of countries are looking to modernize regulatory approaches for these products, based on risk (or lack thereof) and similarity to organisms that could be produced via conventional breeding methods. Advances in animal biotechnology, especially genome editing, can accelerate the incorporation of valued phenotypes in animals, including enhanced yield, disease resistance, resilience to changing climate, and improved animal welfare, as well as food qualities valued by consumers. For animals with these biotechnology-introduced traits to enter agricultural production and reach consumers, clear risk-proportionate regulatory approaches must be in place, and to facilitate international trade of animal products, regulatory processes need to be aligned and compatible. Effective scientific public communication is crucial to build public trust in precision animal biotechnology and risk-proportionate regulatory approaches. An international workshop on regulatory approaches for animal biotechnology was convened in 2022 with 27 countries represented. We synthesize here technical progress, development of regulatory policy, and strategies for engagement with diverse publics on animal biotechnology reported in the workshop. Our goal is to encourage development and implementation of risk-proportionate regulatory approaches and policies in a global context.

1. We assessed genetic variation at mitochondrial DNA (mtDNA) and nuclear DNA microsatellites for progeny (i.e., juveniles produced at a hatchery) of five endangered Epioblasma species reared at three hatcheries in the eastern United States. 2. The progeny of Epioblasma aureola, Epioblasma brevidens, Epioblasma obliquata and Epioblasma triquetra showed no loss of mtDNA haplotype diversity relative to broodstock (i.e., wild collected gravid females used to produce juveniles) and wildstock (i.e., individuals sampled in the wild to assess baseline genetic diversity), while progeny of Epioblasma capsaeformis showed no loss relative to broodstock but an similar to 50% loss relative to wildstock. 3. At DNA microsatellites, mean expected heterozygosities (H-e) were maintained in wildstock, broodstock and progeny, with the lowest values observed in E. aureola and E. triquetra. Among progeny, values of H-e and allelic richness (A) at times exceeded those observed in the wildstock and broodstock. Hence, no loss of genetic variation at DNA microsatellites was observed in progeny among species. 4. We documented multiple paternity in progeny of E. aureola, E. capsaeformis and E. obliquata and in part attribute their high H-e and A to fertilization of broodstock females by multiple males in the wild. 5. We observed significant divergence in F-ST and D values between progeny to wildstock and progeny to broodstock. Most pairwise comparisons for E. brevidens and E. capsaeformis were significantly diverged, and for E. obliquata, divergence was low but also significantly different, and only for E. aureola was it low and nonsignificant. 6. Our results showed that population genetic structure can develop quickly between progeny and their progenitors in the first generation (F-1) of offspring produced from a set of parents and that genetic diversity at mtDNA and nuclear DNA microsatellites was generally maintained in progeny of endangered Epioblasma species reared at three mussel hatcheries utilizing current propagation practices.

Genome editing (GnEd) has the potential to provide many benefits to animal agriculture, offering a means for achieving rapid growth, disease resistance, and novel phenotypes. The technology has the potential to be useful for rapidly incorporating traits into existing selectively bred animals without the need for crossbreeding and backcrossing. Yet only four products from animals created via biotechnology, all growth-enhanced fishes, have reached commercialization and only on a limited scale. The past failure of genetically engineered (or GM) products to reach conventional producers can largely be attributed to the high cost of meeting GMO regulatory requirements. We review the history of GMO regulations internationally, noting the influence of Codex Alimentarius on the development of many existing regulatory frameworks. We highlight new regulatory approaches for GnEd organisms, first developed by Argentina, and the adoption of similar approaches by other countries. Such new regulatory approaches allow GnEd organisms that could have been developed by conventional means to be regulated under the same rules as conventional organisms and in the future is likely to enhance the opportunity for biotech animals to enter production. Treating certain GnEd products as conventional has had a large impact on the variety of biotechnological innovations successfully navigating regulatory processes. We suggest that for the full potential of GnEd technologies to be realized, enabling public policies are needed to facilitate use of GnEd as a breeding tool to incorporate new traits within existing animal breeding programs, rather than only a tool to create distinct new products.

In Lar National Park (Caspian Sea basin, Iran), the Caspian trout (Salmo caspius) population faces different threats, including introduced fish species. Due to the harsh environmental conditions and limited accessibility, monitoring of fish species via conventional approaches proves difficult. Hence, environmental DNA metabarcoding may prove an appropriate tool for monitoring fishes within the park. Environmental DNA samples from eight stream sites in the National Park were sequenced via metabarcoding of the 12S rRNA gene, and the species identified via eDNA metabarcoding were compared to the results of electrofishing performed at the same localities on the same day. No significant difference in the number of Caspian Sea trout DNA sequence reads was detected among the collection sites (p > 0.05). The highest number of reads was detected in Dalichay Stream, but the highest population density determined via electrofishing was in Siahpalas Stream. The discrepancy between the eDNA read count and trout population density, as well as the limited sampling scheme within this study, limit our ability to provide a robust conclusion about the application of environmental DNA metabarcoding for assessment of fish density in Lar National Park. Environmental DNA metabarcoding detected more species than electrofishing, but no significant differences in the composition of the local fish community were observed. Introduced fish species were all observed or detected in Siahpalas Stream, which is characterized by high water temperature, muddy substrate, and lower flow rate. A significant effect of flow rate and total dissolved solids on the presence of introduced fish species (p = 0.02) and of flow rate alone on relative abundance of introduced fish species (p = 0.03) was detected. To standardize the application of eDNA metabarcoding as a biodiversity assessment tool in Lar National Park, future studies should characterize the parameters that affect eDNA persistence and detectability in the system.

Objective: This paper applies a catch multiple survey analysis (CMSA) to Atlantic horseshoe crabs Limulus polyphemus in the Delaware Bay to generate robust population estimates for harvest management. Currently, horseshoe crabs along the U.S. Atlantic coast are harvested as bait for other fisheries and collected for their blood, which is used in a biomedical industry. The Delaware Bay is home to the largest population of horseshoe crabs and is a significant stopover for shorebirds to rebuild energy by consuming horseshoe crab eggs prior to completing their northward migration. To address this interrelationship, the Adaptive Resource Management (ARM) Framework has been used since 2013 to ensure that horseshoe crab harvest within the region takes into account the forage needs of migratory birds. Since its inception, the ARM Framework has used a single trawl survey's swept area-based population estimates of horseshoe crab relative abundance and a theoretical population model developed primarily from literature-derived values. With more data collected in the region in recent years and other sources of mortality that can now be quantified, a catch survey model can provide horseshoe crab population estimates going forward.Methods: A CMSA was used to estimate male and female horseshoe crab population size for 2003-2021 using all quantifiable sources of mortality and three fishery-independent indices of abundance.Result: The CMSA results indicated that adult abundance of male and female horseshoe crabs was stable from 2003 to 2013 and then began to increase through 2017, a result that is consistent with stock rebuilding following a period of harvest restrictions as recommended by the ARM Framework. Population estimates were lower in recent years but remained above the levels estimated before implementation of the ARM Framework. In 2021, the CMSA estimated that there were over 6 million mature females and nearly 16 million mature male horseshoe crabs in the region.Conclusion: The CMSA provides the best and most comprehensive population estimates of horseshoe crabs in Delaware Bay and will improve modeling efforts within the ARM Framework going forward.

Genetics and biotechnology make increasingly important contributions to fishery science, fishery management, aquaculture, and related fields [...]

Species of the genus Pseudoplatystoma, the long-whiskered catfishes, are important in commercial and recreational fisheries in South America, and some species have become key to regional aquaculture. Some species of the genus are under pressure due to overfishing and the negative impacts of dams. Six questions are asked in this review: (i) What species are in the genus, and where are they distributed? (ii) What are the life histories and ecologies of Pseudoplatystoma species? (iii) What are the patterns of somatic growth for these species? (iv) What is known about the biomass, production, and population dynamics of Pseudoplatystoma? (v) What is the geographic distribution of genetic variation within Pseudoplatystoma species? (vi) What are the threats to the conservation of these species? The taxonomy of the genus currently includes eight species, respectively, distributed over the Orinoco, Amazon, Paraná, and São Francisco basins. Pseudoplatystoma catfishes typically exhibit longitudinal migrations for reproduction and lateral migration for feeding, but these patterns may vary among populations. The size of the first maturation of these catfishes varies between 57 cm to 82 cm in total length. Five of the eight species spawn during the rising water season. Pseudoplatystoma species can grow to about 130 cm in total length and 100 Kg in weight and live until 30 years of age, depending upon the species. Biomass production and population dynamics of these catfishes have not yet been fully described. Their life-history characteristics indicate that they are periodic strategists with associated population recruitment dynamics. Population genetic patterning varies among Pseudoplatystoma species, with some degree of homing behavior and genetic differentiation among populations, indicating the need for management by applying the Management Unit and perhaps Evolutionary Significant Unit concepts. The main threats to the persistence of these catfishes are overfishing and alterations in and obstruction of river flow due to the construction of hydropower dams. After synthesizing existing information on species of the genus Pseudoplatystoma, we offer suggestions for future research to fill critical gaps in the knowledge of this group.