Marine‐climate interactions with the blue shark (Prionace glauca) catches in the western coast of Baja California Peninsula, Mexico

Abstract

Fishery and size data by sex of 28,110 blue sharks (Prionace glauca) from 2162 longline sets documented by observers on board 204 fishery trips from the industrial fleet based in Ensenada, Mexico during 2006–2016, were used to conduct a spatial–temporal analysis of the catch‐per‐unit‐effort (CPUE) and its relationship with climate indices along the west coast of the Baja California Peninsula. Catch length analysis by maturity groups indicated catches were composed mainly by juvenile females (58–199 cm TL) and males (60–179 cm TL). Relationships of seasonal CPUE with sea surface temperature (SST) and Chlorophyll‐a (Chl) were analyzed determining aggregations were in areas characterized by oceanographic physical processes. From the exploratory analysis of annual correlations of climate indices with CPUE, the local climate SanDiAs Index explained most variation in CPUE. A generalized additive model (GAM) with 13 predictor variables was applied to gain insight on their relationship with the total CPUE by size and sex groups. The model explained 50.5% of the total blue shark CPUE and 65.5% for juvenile females. The GAM results revealed blue shark CPUE is influenced by five relevant factors: SST, NPGO, year, latitude with distance to coast and quarter interactions, and hooks set. There is a trend to increase or decrease of CPUE when compared with the delay of NEI and SanDiAs indices in more than 1 year. Local and regional climate indices can be successful tools for forecasting blue shark catches in the Northwestern Mexican Pacific.

Exempted and Research Deep-Set Fishing Trials for Swordfish, Xiphias gladius, in the Southern California Bight, 2017–21

“…This is most likely due to the seasonality of sets, as the research sets during the same period revealed similar catch composition. Further, nearly all LBG EFP sets occurred during the months of July through October, whereas the majority of the blue shark catch occurred later in the swordfsh season (November-January) when blue shark abundance increased off southern California (Hanan et al, 1993;Sepulveda and Aalbers, 2018;Godínez-Padilla et al, 2022).…”

Effects of marine climate variability on the relative abundance of Lutjanus purpureus (POEY, 1866) on the Amazon Continental Shelf

“…In this context, the Generalized Additive Models (GAM) and Cross Wavelets are specific tools that help us to understand multiple variables in a same problem that can be ecological and economic approaches. Nowadays, this way of analysis has been widespread used in fisheries field (Godínez‐Padilla et al, 2022; Li et al, 2023; Ma et al, 2023).…”

“…In this context, the Generalized Additive Models (GAM) and Cross Wavelets are specific tools that help us to understand multiple variables in a same problem that can be ecological and economic approaches. Nowadays, this way of analysis has been widespread used in fisheries field (Godínez-Padilla et al, 2022;Li et al, 2023;Ma et al, 2023). This is crucial if our objective is to strengthen conservation policies and improve fisheries management in the region influenced by the Amazon River (Jongman et al, 1995;Pinaya et al, 2016).…”

First evidence of multiple paternity in the blue shark (Prionace glauca)

“…The blue shark Prionace glauca L. 1758 is one of the most abundant and widely distributed shark species (Nakano & Stevens, 2008), and has the highest capture rates on both incidental and directed fisheries (Bailleul et al, 2018;Campana et al, 2009;Compagno, 1984;Godínez-Padilla et al, 2016;Nakano & Stevens, 2008). Here the authors genetically analysed samples of P. glauca from the Mexican northeast Pacific Ocean to test the presence of MP in the species.…”