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Catch and effort data from 29 418 longline sets from Brazilian tuna longline vessels operating in the south-western and equatorial Atlantic Ocean between 2004 and 2011 were analysed to investigate the distribution, catch rate and size of three species of hammerhead sharks ( Sphyrna lewini, Sphyrna mokarran and Sphyrna zygaena). During that period, 6172 hammerhead sharks were caught. Among the elasmobranchs, the highest percentage of hammerhead sharks were caught in 2007, when they accounted for 3·90% of the group, while the lowest value of 0·40% was recorded in 2010. In general, the spatial distribution of the mean catch per unit effort ( CPUE) by years and quarters showed a trend of higher catches near the equatorial region and in southern Brazil. The nominal mean CPUE was 0·12 Sphyrna spp. 1000−1 hooks, with the highest value being recorded in 2007 (0·30 Sphyrna spp. 1000−1 hooks). The standardized yearly CPUE estimated by a generalized linear model assuming a zero inflated negative binomial ( ZINB) distribution were not much different from nominal values. Of the 205 sexed specimens, 117 were females and 88 were males, resulting in a sex ratio with a predominance of females (1·30:1·00), although not statistically significant. The total length of females ranged from 1200 to 2800 mm and of males from 1100 to 3100 mm. Juvenile hammerhead sharks represented 82 and 54% of the sexed female and male specimens, respectively. [ABSTRACT FROM AUTHOR]

Blue shark ( Prionace glauca ) populations are decreasing worldwide and the species is currently classified as near threatened. However, it is the main species caught by the Spanish and Portuguese longline fisheries; and blue shark is specifically targeted by a part of these fleets in the northeastern Atlantic Ocean. Sharks are well known to be able to detect electric fields in the microvolt range and this sense has been proposed to provide a mechanism to detect the earth's magnetic field. As a result, the use of magnets has been proposed as a method to reduce shark interactions with fishing gear. We therefore tested two models of high field strength neodymium magnets to effect shark catch rates during commercial longline fishing operations. Our results show that magnets do not reduce blue shark catch rates and can even have an attractive effect. This effect was significantly higher for the larger magnet model tested (26 mm × 11 mm × 12 mm, 0.885 T) compared to the smaller one (20 mm × 13 mm × 15 mm, 0.464 T). We also noted that hooks remain magnetized after removal of the magnets and are even slightly magnetized without any previous contact with a magnet. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate spatiotemporal patterns in the distribution and relative abundance of blue sharks and their relationship with environmental variables and oceanographic processes in the southwestern Atlantic Ocean. We modeled data on catch records from the Brazilian pelagic tuna longline fleet using generalized additive models (GAMs). The distribution of Prionace glauca was influenced by salinity, chlorophyll-a and temperature. Our models showed that both the catch per unit of fishing effort (CPUE) and the probability of presence increased mainly between March and August. The CPUE was also influenced by ocean depth and sea surface height, and the probability of occurrence by ocean fronts and slope. The highest CPUE values and probability of occurrence of blue sharks tended to occur mainly in parts of the continental slope off Brazil and at the Rio Grande Rise, characterized by the presence of seamounts. Such hotspots for P. glauca could potentially be considered in fisheries management plans., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Abstract: Catch and effort data from 14,835 longline sets conducted by foreign tuna longline vessels chartered by Brazil, from 2004 to 2010, were analyzed aiming at assessing the size, distribution and the relative abundance of the oceanic whitetip shark (Carcharhinus longimanus) in the southwestern and equatorial Atlantic Ocean. The nominal catch per unit of effort (CPUE) exhibited a gradual increase, from 0.04 sharks/1000 hooks, in 2004, the first year of the time series, up to 0.13, in 2007. In 2008, however, the CPUE increased sharply, reaching 0.43, dropping, then, back to 0.15, in 2010. A CPUE standardization was performed using a delta-GLM approach, but the standardized index of abundance did not differ significantly from the nominal CPUE. The models indicated that the catches of oceanic whitetip sharks are higher for the Spanish fishing strategy, which is characterized by the deployment of hooks at shallower depths. These results indicate that the use of deep longline hooks (>100m) may help to mitigate the bycatch of this species. [Copyright &y& Elsevier]

The nurse shark, Ginglymostoma cirratum, is an abundant coastal species widely distributed on both sides of the tropical and subtropical Atlantic Ocean. Despite being an endangered species in Brazil, information on bio-ecological aspects of this species is still very scarce. This study investigates seasonal fluctuations in abundance, sex ratio and residency of nurse sharks in coastal waters off Recife, northeastern Brazil. Total length of the specimens caught ranged from 107 to 300 cm. Sex ratio for nurse sharks was 1.31♀:1♂ but it showed a strong variation throughout the year. About 8% of tagged sharks were recaptured after an average of 248 days at liberty, at distances between 0.04 and 6.23 km from the tagging site. A growth rate of 15.77 ± 2.53 cm/yr was obtained from total length data collected from three recaptured specimens. Nurse sharks demonstrated some signs of affinity for temperatures between 25º and 30°C and salinities between 34 and 37. The combined analysis of longline and telemetry data indicated possible differences in habitat usage between sexes of nurse sharks off Recife. [ABSTRACT FROM AUTHOR]

The present study analyses the spatial and temporal distribution of the pelagic stingray (Pteroplatytrygon violacea) in the south-western Atlantic Ocean, based on data collected between April 1998 and March 2006 by the National Observers Program of the Uruguayan Tuna Fleet. During this period, data were recorded on 51 commercial fishing trips, in which a total of 2 306 851 hooks were set and 2740 stingrays captured. Of these, the sex was determined for 1329 individuals and the size for 944. The average disc width was 47 ± 8 cm (range: 24-82 cm) for females and 44 ± 5 cm (range: 28-84 cm) for males. The results indicate that the species seems to prefer warm temperate and tropical waters. There were no capture records in waters at <15.3 °C. The data collected suggest a mating season in late spring with a gestation period of 2 to 4 months and births occurring during late summer and early autumn. The increasing bycatch of this ovoviviparous species in pelagic longline fisheries, with an unknown survival rate after discard, coupled to its low reproductive potential, call for better monitoring in order to accurately determine its current conservation status. [ABSTRACT FROM AUTHOR]