Length at Maturity, Sex Ratio, and Proportions of Maturity of the Giant Electric Ray, Narcine entemedor, in Its Septentrional Distribution

The size at which a certain fraction of a fish population reaches sexual maturity is an important parameter of life history. The estimation of this parameter based on logistic or sigmoid models could provide different ogives and values of length at maturity, which must be analyzed and considered as a basic feature of biological reproduction for the species. A total of 305 individuals of Narcine entemedor (N. entemedor) were obtained from artisanal fisheries in the Bahía de La Paz, Mexico. For the organisms sampled, sexes were determined and total length (TL) in cm was measured from October 2013 to December 2015. The results indicated that the females were larger, ranging from 48.5 cm to 84 cm TL, while males varied from 41.5 cm to 58.5 cm TL. The sex ratio was dominated by males ranging from 45–55 cm TL, while females were more abundant from 60 to 85 cm TL. Mature females were present all year long, exhibiting a continuous annual reproductive cycle. The length at maturity data were described by the Gompertz model with value of 55.87 cm TL. The comparison between models, and the model selection between them, showed that the Gompertz model had maximum likelihood and smaller Akaike information criterion, indicating that this model was a better fit to the maturity proportion data of N. entemedor.

TEMPORAL CHANGES IN LENGTH-WEIGHT RELATIONSHIPS OF SCIAENIDAE (PISCES: TELEOSTEI) SPECIES IN SOUTH BRAZIL

This study reports the importance to evaluate the length-weight relationships (LWR) across the years. We evaluate the LWR for 8 Sciaenidae species of Paranaguá Estuarine Complex, South Brazil, sampled between 2016 and 2018 by bottom trawls similar to the used by artisanal fisheries in this region. There were differences between growth type among the years for 5 species, and all species showed differences in the slope of LWR in at least one year. These results show the importance of fauna and fisheries monitoring programs to better evaluate the population dynamics and fisheries stocks. Keywords: estuarine fish, fisheries biology, marine fish, sciaenid, weight-length relationship

Small-scale fisheries in Madeira: recreational vs artisanal fisheries

Small-scale recreational and artisanal fisheries are popular activities in the Autonomous Region of Madeira, and to date no information is available on their impact on regional coastal ecosystems. Through fishers’ surveys and official registers of fish landings, we described and characterized these fisheries in Madeira, comparing artisanal and recreational fisheries. In 2017, artisanal boats landed 91 species in fishing ports, while recreational catches landed 58 species. The most frequent catches were Dentex gibbosus, Phycis phycis and Pagrus pagrus for artisanal fishery and P. pagrus, Serranus atricauda and Diplodus spp. for recreational fishery. Comparing the same techniques, artisanal fishery always showed higher catch per unit effort values than recreational boat fishery. Nevertheless, the low number of artisanal fishery boats in comparison with the recreational ones reflected the lower total landings of the artisanal fishery, which in 2017 were 62.3 t, compared with the 509.8 t estimated catches for the recreational fishery. Though the estimated recreational fishing data were based on surveys and thus subject to various biases, this activity seems to negatively affect coastal ecosystems and, together with artisanal fishing, exerts a combined pressure on targeted species. Improved legislation for both fisheries is essential for an appropriate management of resources.

The Biology of Mesopelagic Fishes and Their Catches (1950–2018) by Commercial and Experimental Fisheries

Following a brief review of their biology, this contribution is an attempt to provide a global overview of the catches of mesopelagic fishes (of which 2.68 million tonnes were officially reported to the FAO) throughout the world ocean from 1950 to 2018, to serve as a baseline to a future development of these fisheries. The overview is based on a thorough scanning of the literature dealing with commercial or experimental fisheries for mesopelagics and their catches, and/or the mesopelagic bycatch of other fisheries. All commercial (industrial and artisanal) fisheries for mesopelagic fishes were included, as well as experimental fisheries of which we were aware, while catches performed only to obtain scientific samples were omitted. The processes of generating bycatch and causing discards are discussed, with emphasis on Russian fisheries. From peer-reviewed and gray literature, we lifted information on mesopelagic fisheries and assembled it into one document, which we then summarized into two text tables with catch data, one by country/region, the other by species or species groups.

Climate Change and Fisheries: Perspectives from Small-Scale Fishing Community in Badagry, Lagos, Nigeria

The present study focused on impact of climate change on livelihood of Ganyingbo fishing community in Badagry, from June to September, 2020. Data were collected through administration of 58 structured questionnaires to artisanal fishermen while test of significance of research hypotheses was conducted using chi-square and t-test at 95% confidence interval. The results showed that the fisher folks composed of 83% male and 17% female. The most common age group among fishermen was 30-39 years (27.58%) and 57% do not have other job apart from fishing. Majority (37.93%) of the fishermen did not attain beyond secondary school education while only 3.45% had tertiary education. Calculated coefficient of marketing efficiency indicated that 54.8% and 72.26% of their sales revenue were taken up by costs before and after the effect of climate change respectively. Total expenditure of fishermen increased by 24.9% while income decreased by 5.26%. The t-test analysis indicated significant (p<0.05) difference between the total cost associated with fishing in Ganyingbo before (N17850.0± 2015.22) and after (N22300.0 ± 6297.40) effect of the climate change. Fishermen (87.93%) believed that adopting coping strategies to mitigate the climate change is germane for artisanal fisheries systems. A significant (p<0.05) difference was observed (X2 = 30.56: 9.49) between expected and observed perspective of fishermen based on viability of artisanal fisheries in Ganyingbo community. As noted in this study, fishing business in Ganyingbo is still viable however more effective mitigation measures are required to ensure its sustainability.

Evaluating artisanal fishing of globally threatened sharks and rays in the Bay of Bengal, Bangladesh

Sharks and rays are at risk of extinction globally. This reflects low resilience to increasing fishing pressure, exacerbated by habitat loss, climate change, increasing value in a trade and inadequate information leading to limited conservation actions. Artisanal fisheries in the Bay of Bengal of Bangladesh contribute to the high levels of global fishing pressure on elasmobranchs. However, it is one of the most data-poor regions of the world, and the diversity, occurrence and conservation needs of elasmobranchs in this region have not been adequately assessed. This study evaluated elasmobranch diversity, species composition, catch and trade within the artisanal fisheries to address this critical knowledge gap. Findings show that elasmobranch diversity in Bangladesh has previously been underestimated. In this study, over 160000 individual elasmobranchs were recorded through landing site monitoring, comprising 88 species (30 sharks and 58 rays) within 20 families and 35 genera. Of these, 54 are globally threatened according to the IUCN Red List of Threatened Species, with ten species listed as Critically Endangered and 22 species listed as Endangered. Almost 98% juvenile catch (69–99% for different species) for large species sand a decline in numbers of large individuals were documented, indicating unsustainable fisheries. Several previously common species were rarely landed, indicating potential population declines. The catch pattern showed seasonality and, in some cases, gear specificity. Overall, Bangladesh was found to be a significant contributor to shark and ray catches and trade in the Bay of Bengal region. Effective monitoring was not observed at the landing sites or processing centres, despite 29 species of elasmobranchs being protected by law, many of which were frequently landed. On this basis, a series of recommendations were provided for improving the conservation status of the elasmobranchs in this region. These include the need for improved taxonomic research, enhanced monitoring of elasmobranch stocks, and the highest protection level for threatened taxa. Alongside political will, enhancing national capacity to manage and rebuild elasmobranch stocks, coordinated regional management measures are essential.