Abstract
Climatic effects on the growth of apex marine predators – such as sharks – are poorly understood; moreover, shifts in shark growth are primarily attributed to fishing pressure. This paucity of information impedes management and conservation planning for these taxa. Using vertebral increment patterning as a proxy of somatic growth, this study reconstructed mean growth of the philopatric and demersal Heterodontus portusjacksoni population from Gulf St Vincent (South Australia). A biochronology of shark growth spanning 1996 to 2010 was developed using linear mixed effect models. The biochronology showed considerable year-to-year deviations in growth that were significantly and negatively correlated with mean sea surface temperatures during the species’ breeding season (July to November). These findings are consistent with mesocosm experiments and support the influence of changing climates on shark growth; particularly in an inshore, demersal and highly philopatric shark species. It is likely that the effects of environmental variation occur in a species-specific manner, governed by life history strategies and ecological requirements. In this manner, life history traits might aid in estimating species vulnerability to climate change.
Highlights
Environmental controls on the phenology and biology of terrestrial and aquatic taxa are well established (Parmesan, 2006)
Centrum diameter was significantly correlated to total length (Figure 3), confirming that Port Jackson shark vertebrae provide suitable proxies of somatic growth, developing in proportion to total length (Figure 3)
This study demonstrates that in the absence of targeted fishing pressure, shark growth fluctuates through time; with Port Jackson shark population growth negatively correlated with sea surface temperature over a 15 year period
Summary
Environmental controls on the phenology and biology of terrestrial and aquatic taxa are well established (Parmesan, 2006). Key biological processes, such as growth, have been linked to temperature, with fluctuations in external conditions correlated to variations in growth. This is well-established in teleosts; with particular interest in climate change effects (Morrongiello et al, 2012). Biochronologies provide a means of measuring growth deviations though time, using the incremental patterns of calcified structures as proxies of somatic growth (Morrongiello et al, 2012). Possess analogous incremental growth patterns and are widely used to estimate (Environmentally) Sensitive Sharks chronological age (Cailliet and Goldman, 2004), with vertebral increments potentially providing suitable proxies of somatic shark growth when allometry is validated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
