Search

Catch-and-release angling of salmonids is a widely implemented fisheries management strategy intended to provide recreational fishing opportunities while limiting harvest. Previous research has indicated mortality may be low, but the extent of sublethal impacts, including inability to reach spawning grounds or decreased spawning effectiveness, is relatively understudied. Sockeye salmon (Oncorhynchus nerka) were subjected to simulated catch-and-release events, with a subset also enduring air exposure, to determine how physiological stress influences the ability of sockeye salmon to reach spawning grounds and the viability of eggs produced. Short-term postrelease mortality was highest for fish that were subjected to air exposure, but once recovered, neither simulated catch-and-release nor air exposure had a major impact on their ability to reach spawning grounds. Egg viability was similar between treatment groups, indicating physiological stress associated with the trials did not have a negative impact on reproduction. These results suggest that handling, especially air exposure, is the primary concern and substantially impacts the short-term postrelease mortality of sockeye salmon, which has important implications for management. La peche avec remise a l'eau de salmonides est une strategie de gestion des peches largement utilisee pour offrir des possibility de peche sportive tout en limitant les prises. Des travaux anterieurs ont indique que la mortalite pourrait etre faible, mais l'ampleur des impacts subletaux, dont l'incapacite de rejoindre les lieux de frai ou une reduction de l'efficacite du frai, demeure relativement peu etudiee. Des saumons rouges (Oncorhynchus nerka) ont ete assujettis a des evenements de capture avec remise a l'eau simulee, un sous-ensemble etant aussi expose a l'air, afin de determiner l'influence du stress physiologique sur la capacite des saumons rouges de rejoindre leurs lieux de frai et sur la viabilite des reufs produits. La mortalite a court terme suivant la remise a l'eau etait la plus elevee pour les poissons exposes a l'air, mais une fois que les saumons s'etaient remis, ni la capture avec remise a l'eau simulee ni l'exposition a l'air n'avait d'impact significatif sur leur capacite de rejoindre les lieux de frai. La viabilite des reufs etait semblable pour les deux groupes traites, ce qui indique que le stress physiologique associe aux essais n'a pas eu d'impact negatif sur la reproduction. Ces resultats donnent a penser que la manipulation, en particulier l'exposition a l'air, est l'enjeu le plus preoccupant et qu'elle a un impact significatif sur la mortalite a court terme apres remise a l'eau des saumons rouges, ce qui a d'importantes consequences en ce qui concerne la gestion., Introduction Salmon fisheries have a lengthy history in North America, especially in the Pacific Northwest where many residents still rely upon commercial, recreational, and subsistence fisheries. However, salmon populations have [...]

Shark predation risk impacts many facets of dolphin life, including habitat use and foraging strategies. Because direct predation is rarely observed, researchers instead examine dolphins in situ for past injuries that can be attributed to sharks. We analyzed existing photo‐ID catalogs of common bottlenose (Tursiops truncatus) and Atlantic spotted dolphins (Stenella frontalis) off Bimini, The Bahamas. A minimum of 29% of individual T. truncatus had evidence of a past, nonlethal shark bite, while for S. frontalis this was only 15%. For both species, shark‐induced injuries were predominantly on the dorsal side. Regression analyses indicated that T. truncatus were more likely to have shark bite scars than S. frontalis and the likelihood of documenting a shark bite scar increased with a higher percentage of the body photographed. T. truncatus were less likely to have scars in the dorsal region, but sampling differences could have influenced these results. While the shark species responsible for scars was not determined, T. truncatus and S. frontalis overlap spatially and temporally with tiger (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas) off Bimini. This study builds on the understanding of dolphin/shark interactions from longitudinal studies of dolphins in this region, providing insight into factors influencing predation risk. [ABSTRACT FROM AUTHOR]

Consistent individual differences in behaviour (i.e. personality) can be explained in an evolutionary context if they are favoured by life history trade‐offs as conceptualized in the pace‐of‐life syndrome (POLS) hypothesis. Theory predicts that faster‐growing individuals suffer higher mortality and that this trade‐off is mediated through exploration/risk‐taking personality, but empirical support for this remains limited and ambiguous. Equivocal support to the POLS hypothesis suggests that the link between life history and personality may only emerge under certain circumstances. Understanding personality‐driven trade‐offs would be facilitated by long‐term studies in wild populations experiencing different ecological conditions.Here, we tested whether personality measured in semi‐captivity was associated with a growth‐mortality trade‐off via risk‐taking in the wild in two subpopulations of juvenile lemon sharks Negaprion brevirostris known to differ in their predator abundance. We expected stronger personality‐driven trade‐offs in the predator‐rich environment as compared to the predator‐poor environment.Sharks were captured yearly from 1995 onwards allowing us to obtain long‐term data on growth and apparent survival in each subpopulation. We then used a novel open‐field assay to test sharks for exploration personality yearly from 2012 to 2017. A subset of the tested sharks was monitored in the field using telemetry to document risk‐taking behaviours. We tested (a) if fast explorers in captivity took more risks and grew faster in the wild and (b) if natural selection acted against more explorative, faster‐growing sharks.In the subpopulation with fewer predators, more explorative sharks in captivity took more risks in the wild and grew faster. In turn, larger, fast‐growing sharks had lower apparent survival. In the predator‐rich subpopulation, despite finding selection on fast growth, we found no link between exploration personality and the growth‐mortality trade‐off.Our study demonstrates that the association between personality and life history is favoured in some ecological contexts but not in others. We identify predator and resource abundance as two main potential drivers of the personality‐mediated trade‐off and emphasize that future work on the POLS hypothesis would benefit from an approach integrating behaviour and life history across ecological conditions. [ABSTRACT FROM AUTHOR]

An intact and uncompromised internal acoustic transmitter was non‐lethally recovered from a lemon shark Negaprion brevirostris, after 13 years at liberty. The shark, first tagged at an estimated age of 2 years old near South Bimini, Bahamas in 2004, was recaptured in 2017 with a total length of 264 cm. The tagged shark displayed typical growth rate, pregnancy, natal homing and pupping behaviour of other individuals in this population. This observation provides important evidence regarding the effects from long‐term retention of implanted acoustic transmitters in a carcharhinid shark. [ABSTRACT FROM AUTHOR]