Seasonal patterns of adult and subadult white shark presence at coastal aggregation sites in central California DOI
Samantha Andrzejaczek, Taylor K. Chapple, Alexandra E. DiGiacomo

et al.

Wildlife Research, Journal Year: 2025, Volume and Issue: 52(5)

Published: May 6, 2025

Context Gaining insights into seasonal aggregations of marine megafauna and how patterns vary among demographic groups is pivotal for evaluating anthropogenic risk exposure modeling populations ecosystem dynamics. In California, adult subadult white sharks recurrently aggregate on the coast near pinniped colonies in fall winter months, facilitating comprehensive long-term field studies. Aims this study, we used over 15 years passive acoustic telemetry data to compare dynamics coastal habitat use tagged central California four (adult females, males, males). Methods Acoustic tags were deployed 355 at aggregation sites monitored across a array underwater receivers from 2006 2022. The main Northeast Pacific (Año Nuevo, Farallon Islands Tomales) continuously monitored, with an expansion network south latter study. Key results White tracked average duration 594 ± 552 days (mean s.d.), total track durations ranging up 3235 days. Notably, male exhibited highest residency demonstrated earlier peak densities late October. Adult female presence peaked early December. displayed distinct gaps detection where they have been shown satellite migrate offshore, females displaying much longer than males (averaging 1.5 vs 0.7 years). contrast, subadults higher affinity more consistent widespread detections number throughout year, often extending beyond areas outside season. Conclusions We hypothesize that observed differences between are attributed sex- size-specific foraging reproductive strategies. extended receiver also showed expansive movements identified potential undescribed sites. Implications Insights our extensive dataset represent significant advancement assessing timing interactions both population

Language: Английский

Evidence for an ecological two-population model for white sharks (Carcharodon carcharias) in Australian waters DOI
Teah Grace Burke, Charlie Huveneers, Lauren Meyer

et al.

Wildlife Research, Journal Year: 2025, Volume and Issue: 52(3)

Published: March 2, 2025

Context Our understanding of population- and ecosystem-level processes commonly considers conspecific individuals to be ecologically equivalent. However, the same species may use resources differently, supporting prevalence individual specialisation or ‘apparent specialisation’. Individuals within a geographically defined population also exhibit complex subpopulation movements, whereby show philopatry specific regions that further drives variation. Aims White sharks (Carcharodon carcharias) are top predators in temperate tropical ecosystems. In Australia, two discrete subpopulations white (an east southwest subpopulation) have been proposed based on genetics limited movement across Bass Strait. We aimed characterise extent ontogenetic divergence resource–habitat behaviour from both regions. Methods used high-resolution retrospective stable isotope profiles (δ15N δ13C) 74 shark vertebral centra examine trophic–habitat signatures for sampled Key results demonstrate isotopic separation between juvenile–subadult (−13.7 ± 0.72 δ13C; 14.2 0.8 δ15N, n = 47) (−14.4 0.6 12.5 1.2 27) Strait, but with strong oscillatory trends regions, likely related seasonal movements. Relative niche width revealed apparent specialised Conclusions Retrospective vertebrae Australian provide evidence support an ecological two-population model juvenile subadult life stages. Implications Given many marine undergoing systematic declines, variation diet context structure true is central elucidating their roles.

Language: Английский

Citations

1
Seasonal patterns of adult and subadult white shark presence at coastal aggregation sites in central California DOI
Samantha Andrzejaczek, Taylor K. Chapple, Alexandra E. DiGiacomo

et al.

Wildlife Research, Journal Year: 2025, Volume and Issue: 52(5)

Published: May 6, 2025

Context Gaining insights into seasonal aggregations of marine megafauna and how patterns vary among demographic groups is pivotal for evaluating anthropogenic risk exposure modeling populations ecosystem dynamics. In California, adult subadult white sharks recurrently aggregate on the coast near pinniped colonies in fall winter months, facilitating comprehensive long-term field studies. Aims this study, we used over 15 years passive acoustic telemetry data to compare dynamics coastal habitat use tagged central California four (adult females, males, males). Methods Acoustic tags were deployed 355 at aggregation sites monitored across a array underwater receivers from 2006 2022. The main Northeast Pacific (Año Nuevo, Farallon Islands Tomales) continuously monitored, with an expansion network south latter study. Key results White tracked average duration 594 ± 552 days (mean s.d.), total track durations ranging up 3235 days. Notably, male exhibited highest residency demonstrated earlier peak densities late October. Adult female presence peaked early December. displayed distinct gaps detection where they have been shown satellite migrate offshore, females displaying much longer than males (averaging 1.5 vs 0.7 years). contrast, subadults higher affinity more consistent widespread detections number throughout year, often extending beyond areas outside season. Conclusions We hypothesize that observed differences between are attributed sex- size-specific foraging reproductive strategies. extended receiver also showed expansive movements identified potential undescribed sites. Implications Insights our extensive dataset represent significant advancement assessing timing interactions both population

Language: Английский

Citations

0