Populations of several billfish species are declining due to overfishing and bycatch, and fundamental aspects of their biology and population dynamics remain poorly understood. We provide the first assessment of the population genetic structure of longbill spearfish (Tetrapturus pfluegeri) in the western Atlantic Ocean. We screened variation at 12 nuclear microsatellite loci (n = 144) and mitochondrial DNA control region sequences (mtCR, n = 177). Both marker types revealed three genetically differentiated clusters, with mean values for microsatellites showing differentiation of FST = 0.136 and DEST = 0.201, and for mtCR FST = 0.645. Microsatellite markers demonstrated moderate-to-high genetic diversity, with a mean allelic richness of 6.73 alleles per locus, moderate heterozygosities (Ho = 0.446, He = 0.604), and a positive inbreeding coefficient (FIS = 0.22) across the three sample collection sites. The overall estimated effective population size was 789.2 (95% CI: 246.7–∞). The mtCR exhibited 96 haplotypes, with high haplotype (0.989 ± 0.003) and nucleotide (0.025 ± 1.3%) diversities. We found higher mean relatedness within clusters than among them, supporting the interpretation of population subdivision and the Wahlund effect. Tajima’s D and Fu’s Fs were negative across all localities, with significant values observed along the Brazilian coast but not in the Caribbean Sea. These neutrality test results, together with low Harpending’s raggedness indices from DNA sequence mismatch distributions, are consistent with historical demographic expansion. Our findings establish a genetic baseline for fishery monitoring and management, contributing to the conservation of T. pfluegeri populations in the western Atlantic Ocean.

The skipjack tuna, Katsuwonus pelamis is the worldwide most fished and economically significant tuna species. In the Atlantic Ocean, the management strategy of the International Commission for the Conservation of Atlantic Tunas (ICCAT) includes two stocks: (a) eastern (SKJ-E) and (b) western (SKJ-W) stocks. However, the genetic cohesiveness between these stocks remains poorly understood. Here, we provide this information through mitochondrial [control region (CR)] and nuclear (intron S7) data. In both markers, high genetic diversity and no contraction signals in effective population sizes were found, supporting the species conservation status as ‘Least Concern’ by the IUCN and the results of the latest ICCAT assessment of the two stocks. In general, no well-defined genetic-geographic structure was detected, which may be explained by the specie life history strategies, such as large population effective sizes and migratory behavior, with a broad geographical distribution, that reduce the isolation, inbreeding, and genetic drift effects. However, pairwise FST values within and between the Eastern and Western Atlantic suggest some weak to moderate genetic differentiation. These results involved mainly the Eastern Temperate Zone, represented herein by the Azores archipelago. It is important to highlight that higher differentiation levels were found between sites from different stocks. In addition, the CR data revealed a weak but significant genetic differentiation between the eastern and western stocks (FST = 0.0006). These results can be used to improve and support the ICCAT management strategies of skipjack tuna stocks, highlighting the need for a reevaluation and possible alignment between Eastern and Western Atlantic management actions.

Blackfin tuna (Thunnus atlanticus) is a small tuna distributed in the western Atlantic Ocean where it is exploited by growing recreational and commercial regional fisheries. In this work, genome-wide genetic variation was analysed to investigate the occurrence of stock subdivision. A de novo assembly of the blackfin tuna genome was generated using Illumina paired-end sequencing data and applied as a reference for population genomic analysis of specimens from nine localities (average sample size per locality n = 72) spanning most of the blackfin tuna distribution range. A total of 2139 single-nucleotide polymorphisms were discovered and genotyped using the double-digest restriction associated DNA sequencing. Pairwise exact homogeneity tests were significant in 24 out of 36 population pairs and significant spatial autocorrelation of genotypes was observed for specimens collected within 2250 km of each other. However, divergence among locality samples was very low (pairwise F-ST range 0.0002-0.0025) and significant temporal variations were detected in localities sampled multiple times. Approaches to detect cryptic groups de novo were unsuccessful. Additional sampling is warranted to determine if multiple stocks need to be defined for management and assess temporal and spatial patterns of gene flow connecting them.

Permeable phylogeographic barriers characterize the vast open ocean, boosting gene flow and counteracting population differentiation and speciation of widely distributed and migratory species. However, many widely distributed species consists of distinct populations throughout their distribution, evidencing that our understanding of how the marine environment triggers population and species divergence are insufficient. The sailfish is a circumtropical and highly migratory billfish that inhabits warm and productive areas. Despite its ecological and socioeconomic importance as a predator and fishery resource, the species is threatened by overfishing, requiring innovative approaches to improve their management and conservation status. Thus, we presented a novel high-quality reference genome for the species and applied a seascape genomics approach to understand how marine environmental features may promote local adaptation and how it affects gene flow between populations. We delimit two populations between the Atlantic and Indo-Western Pacific oceans and detect outlier loci correlated with sea surface temperature, salinity, oxygen, and chlorophyll concentrations. However, the most significant explanatory factor that explains the differences between populations was isolation by distance. Despite recent population drops, the sailfish populations are not inbred. For billfishes in general, genome-wide heterozygosity was found to be relatively low compared to other marine fishes, evidencing the need to counteract overfishing effects. In addition, in a climate change scenario, management agencies must implement state-of-the-art sequencing methods, consider our findings in their management plans, and monitor genome-wide heterozygosity over time to improve sustainable fisheries and the long-term viability of its populations.

We conducted a scientific literature review, and a comprehensive analysis based on international fisheries databases, for dolphinfish (Coryphaena hippurus) from the Western Central Atlantic Ocean (WCA) from 1950 to 2018. This analysis updated the dolphinfish catch and efforts trends in comparison to those calculated in Mahon (1999), the first regional catch review for the species that was conducted with data from the 1950s through the mid-1990s. Results showed that the commercial pelagic longline effort doubled within, and quadrupled outside, of national jurisdictions. Commercial landings increased nearly three-fold, but 23 nations still do not report explicit dolphinfish landings to the FAO yet are known to catch dolphinfish. In the WCA, the US Atlantic recreational fishery represents the largest reporting sector by two-fold. When combined with reported commercial landings for 2016, total direct dolphinfish catch was 14,110 metric tons, of which 62 % was estimated to be recreational catch. Since the first regional fishery analysis of dolphinfish, the uncertainty of the status of the fishery has increased with several nations reporting higher landings of unidentified marine fish species. Also, new burgeoning social (e.g., FAD programs) and environmental processes (e.g., Sargassum blooms) lead to the presumption that higher amounts of juvenile dolphinfish are caught throughout the region. First reports of consequential amounts of dolphinfish bycatch have been documented in the pelagic longline fisheries, as well as the first modeled and anecdotal evidence of stock decline has been suggested. Results stress the immediate need for WCA nations to adopt a precautionary approach for proper fishery management of dolphinfish throughout the WCA, not only to increase spawning biomass but also for overall stock health and its conservation.

The blackfin tuna, Thunnus atlanticus , is a small tropical tuna exploited by recreational and commercial fisheries in various parts of its range. Information on stock structure is needed to develop management plans for this species but is currently lacking. In this work, 470 blackfin tuna from nine geographic populations were assayed at 13 homologous microsatellite markers to provide a first assessment of stock structure across the species range. The overall divergence among locality samples was very low (overall FST = 0.0004) indicating high connectivity of blackfin tuna across their range. No clear grouping of localities in differentiated units was inferred but structuring followed a weak isolation by distance pattern (r = 0.16, P = 0.032). Pairwise exact tests and spatial analysis of molecular variance suggested divergence of the sample collected offshore Baía Formosa (Brazil) possibly reflecting reproductive isolation of Brazilian populations from those in the Caribbean region and further north. Further study of the status of Brazilian populations and the transition between this region and the Caribbean is warranted. Cryptic subdivision within the Northern Hemisphere part of the range is possible and should be evaluated using increased marker density and a more comprehensive geographic coverage.

Since the Miocene profound climatic changes have influenced the biology and ecology of species worldwide, such as their connectivity, genetic population structure, and biogeography. The goal herein is to evaluate the phylogeography of sailfish Istiophorus platypterus between the Atlantic, Indian, and Pacific oceans. Our results evidenced a high genetic diversity and three distinct populations among the ocean basins with limited gene flow among them. In addition, the species is characterized by two deep evolutionary lineages that diverged during the Miocene/Pliocene transition, one of them is circumtropical while the other is restricted to the Atlantic Ocean. These lineages evolved along the successive glacial-interglacial cycles from the Pleistocene and remained isolated from each other in glacial refugium until deglaciation. Assessments of sailfish suggest it may be subject to overfishing and the results herein imply the need to re-evaluate the current stock delimitations and management measures adopted by the Regional Fisheries Management Organizations, especially in the Atlantic and the Indo-Western Pacific oceans to effectively manage the species. In addition, this work highlights that both lineages should at least be treated as two distinct management units in the Atlantic Ocean until their taxonomic status is fully resolved, given their high genetic divergence.

The age of Piaractus brachypomus was determined by decomposing the distribution of length frequencies in cohorts that represented ages, using the Battacharya method; while the growth study was done by inference of multiple models, using the Akaike information criterion (AIC) to select the best fit. The models proposed were the unified versions of the model of Richards (U-Richards), von Bertalanffy (U-von Bertalanffy), Logistic (U-Logistic) and Gompertz (U-Gompertz). The age was between one and three year of age (y), with fish from one y measuring 13.0 ± 1.9 centimeter (cm) of (TL), those from two y 25.2 ± 3.0 cm of total length, and those from three 36.3 ± 2.8 cm of total length. From the statistical point of view, shape of the curve, AIC and biological, the best fit model was the U-Gompertz, which produced a sigmoidal curve determined by an asymptotic length of L ∞ = 71.9 cm of TL, a relative growth rate K = 0.148 y -1 , a point of inflection in the curve T i = 2.02 y and an initial point of the curve W o = 8 cm of TL. P. brachypomus presented a relatively slow growth that makes it vulnerable to fishing exploitation, and therefore, must be properly managed.

Atlantic blue marlin fin spines were sampled from Venezuelan fleets during 2003-2008 for the purpose of estimating age and growth. Transverse sections of the second spine from the first anal fin were sampled from 1708 individuals. Of these, 1638 (95.9%) were readable (774 males, 744 females and 120 indeterminate). Males ranged in size from 130 to 254 cm LJFL, females from 126 to 370 cm LJFL. Samples were scored for visible growth annuli and age-corrected for early annuli lost as a result of increased spine core vascularization. Maximum age estimates based on visible annuli were 19.6 yrs for males and 31.3 yrs for females. After agecorrection the maximum age estimates were revised to 43.4 and 43.5 for males and females, respectively. The von Bertalanffy growth model and alternate variant models are presented for the observed individual LIFL at-age data, and three derived data sets: (1) mean observed LIFL at age, (2) all back-calculated LJFLs at each age, (3) mean back-calculated LJFL at each age for males, females, and combined sex.

Entre las especies de mayor importancia comercial y pesquera de la pesca artesanal del rio Orinoco se encuentra Pseudopatystoma orinocoense, donde el desembarco de peces pequeños motivó la realización de estudios anteriores de evaluación de su población, que demostraron un nivel de sobreexplotación del recurso. Sin embargo, los valores de los parámetros de crecimiento que se usaron en su evaluación han creado cierta incertidumbre por estimarse al aplicar a priori el modelo tradicional de von Bertalanffy, por lo que hubo la necesidad de verificar dichos resultados, utilizando la inferencia de modelos múltiples de crecimiento y el criterio de la información de Akaike (AIC) para seleccionar el modelo de mejor ajuste. Los modelos usados fueron las fórmulas unificadas von Bertalanffy (U-von Bertalanffy), Logístico (U-Logístico) y Gompertz (U-Gompertz), derivados del modelo genérico U-Richardas, cuyos ajustes dependieron de la información contenida en los datos. Cuando los datos incluyeron todas las edades el modelo U-von Bertalanffy produjo el mejor ajuste, coincidiendo con resultados anteriores de crecimiento de la especie. Al excluir las edades de uno y dos años, como ocurre con los datos provenientes de la pesca artesanal debido a la selectividad, el mejor ajuste lo produjeron los modelos U-Logístico y U-Gompertz. Instituto Limnológico, Universidad de Oriente, Departamento de Recursos Acuáticos, Dinámica Poblacional de Peces Continentales. MsC Biología Pesquera.

Se determinó la edad de Piaractus brachypomus descomponiendo la distribución de frecuencias de talla en cohortes que representaron edades, utilizando el método de Battacharya; mientras que el estudio del crecimiento se hizo por la inferencia de múltiples modelos, usando el criterio de la información de Akaike (AIC) para seleccionar el de mejor ajuste. Los modelos propuestos fueron las versiones unificadas del modelo de Richards (U-Richards), von Bertalanffy (U-von Bertalanffy), Logístico (U-Logístico) y Gompertz (U-Gompertz). La edad estuvo comprendida entre uno y tres años (a) de edad, con los peces de un a midiendo 13,0±1,9 centímetro (cm) de longitud total, los de dos a 25,2±3,0 cm de LT, y los de tres a 36,3±2,8 cm de LT. Desde el punto de vista estadístico, forma de la curva, AIC y biológico, el modelo de mejor ajuste fue el U-Gompertz, el cual produjo una curva sigmoidea determinada por una longitud asintótica de L= 71,9 cm de LT, una tasa de crecimiento relativo K = 0,148 a ∞ , un punto de inflexión en la curva Ti-1= 2,02 a y un punto inicial de la curva W= 8 cm de LT. P. brachypomus presentó un crecimiento relativamente lento que la hace vulnerable a la explotación pesquera, y por lo tanto, debe ser adecuadamente administrada.

The age of Piaractus brachypomus was determined by decomposing the distribution of length frequencies in cohorts that represented ages, using the Battacharya method; while the growth study was done by inference of multiple models, using the Akaike information criterion (AMC) to select the best fit. The models proposed were the unified versions of the model of Richards (U-Richards), von Bertalanffy (U-von Bertalanffy), Logistic (U-Logistic) and Gompertz (U-Gompertz). The age was between one and three year of age (y), with fish from one y measuring 13.0 +/- 1.9 centimeter (cm) of (TL), those from two y 25.2 +/- 3.0 cm of total length, and those from three 36.3 +/- 2.8 cm of total length. From the statistical point of view, shape of the curve, A/C and biological, the best fit model was the U-Gompertz, which produced a sigmoidal curve determined by an asymptotic length of L-infinity= 71.9 cm of TL, a relative growth rate K = 0.148 y(-1), a point of inflection in the curve T = 2.02 y and an initial point of the curve W-o = 8 cm of TL. P brachypomus presented a relatively slow growth that makes it vulnerable to fishing exploitation, and therefore, must be properly managed.

This study presents data and estimates reproductive parameters of the sailfish Istiophorus platypterus (Shaw, 1792) in the western Atlantic, useful for future stock assessments of the species in the Atlantic Ocean. During the period 2006-2011, a total of 1132 fish were sampled by scientific observers on board Venezuelan and Brazilian longline vessels and from artisanal fisheries based out of Cumana, Puerto La Cruz and Playa Verde, Venezuela and Cabo Frio, Rio de Janeiro, Brazil. The ovaries of 543 females were classified into five ovarian development phases based on microscopic analysis of the most advanced group of oocytes. Generalized additive models were applied to the gonadal index and sex ratio data in order to assess spatio-temporal trends of the reproductive activity and identify the spawning areas. Space-time effect was a significant factor contributing to changes in sex ratio and reproductive activity. Spawning activity was observed in two distinct areas. On the south-east Brazilian coast spawning peaked during December-February, while in the south-eastern Caribbean Sea spawning occurred between March and September, with its peak in March and April. Using a Bayesian approach, size at 50% maturity was estimated to be 146.12cm (credibility interval of 95%, 138.45-152.09cm). Batch fecundity ranged from 436,800 to 2,492,500 hydrated oocytes per female. This study confirms multiple aggregation spawning for this species in the western Atlantic Ocean.

The contribution of the cachama (Colossoma macropomum) in the species composition of artisanal fi shing landings in the middle Orinoco region has decreased, so the assessment of the sustainable yield of the species and the generation of information for establish conservation measures, was required. Based on the above, evaluation studies of the exploited population were carried out to estimate the age and growth parameters of the species in the Orinoco medial region. Age was determined from the growth rings of the otoliths and the length-age by the retro-calculation procedure. The growth characteristics were determined by inference from multiple models such as von Bertalanff y, Logistico, Gompertz and Schnute-Richards. Then, the best fi t was selected using the Akaike information criterion (AIC). The maximum age was fi ve years in fi sh up to 63 cm in total length, while the growth parameters estimated from an average model between von Bertalanff y and Schnute-Richards models were L∞ = 74.3 cm in length total, K = 0.309 year-1 and to = -0.358 years; with relatively rapid growth.

The blue shark (Prionace glauca) is the most frequently captured shark in pelagic oceanic fisheries, especially pelagic longlines targeting swordfish and/or tunas. As part of cooperative scientific efforts for fisheries and biological data collection, information from fishery observers, scientific projects and surveys, and from recreational fisheries from several nations in the Atlantic and Indian Oceans was compiled. Data sets included information on location, size and sex, in a total of 478,220 blue shark records collected between 1966 and 2014. Sizes ranged from 36 to 394cm fork length. Considerable variability was observed in the size distribution by region and season in both oceans. Larger blue sharks tend to occur in equatorial and tropical regions, and smaller specimens in higher latitudes in temperate waters. Differences in sex ratios were also detected spatially and seasonally. Nursery areas in the Atlantic seem to occur in the temperate south-east off South Africa and Namibia, in the south-west off southern Brazil and Uruguay, and in the north-east off the Iberian Peninsula and the Azores. Parturition may occur in the tropical north-east off West Africa. In the Indian Ocean, nursery areas also seem to occur in temperate waters, especially in the south-west Indian Ocean off South Africa, and in the south-east off south-western Australia. The distributional patterns presented in this study provide a better understanding of how blue sharks segregate by size and sex, spatially and temporally, and improve the scientific advice to help adopt more informed and efficient management and conservation measures for this cosmopolitan species.

A standardized index of relative abundance for sailfish (Istiophorus albicans) was developed by the combination of three data sources, the international billfish program (1987-1990), the Venezuelan Pelagic Longline Observer Program (1991-2011), and the National Observer Program (2012-2014). The index was estimated using Generalized Linear Mixed Models under a delta lognormal model approach. The standardization analysis procedure included year, vessel, area, season, bait, and fishing depth as categorical variables. Diagnostic plots were used as indicators of overall model fitting. The time series show that the relative abundance of sailfish caught by the observed Venezuelan longline fleet reflects a strong drop in the early period of the series, thereafter the series remains somewhat stable with the exception of two peaks that occurred in 1999 and in 2007. A descending trend in the catch is observed towards the final years of the series.

La Organización de las Naciones Unidas para la Alimentación y la Agricultura(FAO), indica que los datos de la producción pesquera venezolana alcanzaron la cifrade 524.000 toneladas en el año 2003, lo cual representó para ese año alrededor del0,6% de la producción mundial de la pesca. Si bien a nivel mundial la contribuciónnacional es relativamente modesta, nuestro país se presenta como un importanteproductor pesquero en el ámbito regional, puesto que las capturas venezolanas en el2003 representaron alrededor del 20% del total correspondiente a la región norte deSuramérica, Mar Caribe y Golfo de México.Los rubros que más contribuyeron a la producción nacional en el 2003 fueron elatún aleta amarilla, capturado principalmente por la flota industrial de cerco en elPacífico Oriental con un total de alrededor de 90.000 toneladas, la sardina capturadaen la región nororiental (área de influencia directa del PMS), por la flota artesanal dechinchorros y cercos, con un total de aproximadamente 142.000 toneladas y la pescade arrastre artesanal de pepitona en el nororiente del país con un total de alrededorde 46.000 toneladas (área de influencia indirecta del PMS). Estas tres especiesrepresentaron alrededor del 53% del total de la producción nacional reportado en2003. A nivel de la economía nacional la contribución del sector pesquero esrelativamente modesta, puesto que representa alrededor del 0,5% del ProductoInterno Bruto (PIB). Sin embargo, en algunos estados del país como Sucre, DeltaAmacuro, Nueva Esparta y Falcón representa un componente fundamental de laeconomía de esas regiones y contribuye significativamente en los diferentes sectoreseconómicos a la generación de empleos y al valor agregado de la producción.

Fisheries provide nutrition and livelihoods for coastal populations, but many fisheries are fully or over-exploited and we lack an approach for analysing which factors affect management tool performance. We conducted a literature review of 390 studies to assess how fisheries characteristics affected management tool performance across both small-scale and large-scale fisheries. We defined success as increased or maintained abundance or biomass, reductions in fishing mortality or improvements in population status. Because the literature only covered a narrow set of biological factors, we also conducted an expert elicitation to create a typology of broader fishery characteristics, enabling conditions and design considerations that affect performance. The literature suggested that the most commonly used management tool in a region was often the most successful, although the scale of success varied. Management tools were more often deemed successful when used in combination, particularly pairings of tools that controlled fishing mortality or effort with spatial management. Examples of successful combinations were the use of catch limits with quotas and limited entry, and marine protected areas with effort restrictions. The most common factors associated with inadequate biological performance were 'structural' issues, including poor design or implementation. The expert-derived typologies revealed strong local leadership, high community involvement and governance capacity as common factors of success across management tool categories (i.e. input, output and technical measures), but the degree of importance varied. Our results are designed to inform selection of appropriate management tools based on empirical data and experience to increase the likelihood of successful fisheries management. (Less)