Foraging diversity in lactating New Zealand sea lions: insights from qualitative and quantitative fatty acid analysis

Lactating New Zealand sea lions exhibit distinct foraging strategies that significantly impact their energy expenditure and diet composition. Benthic foragers, which dive deeper and spend more time at sea, show higher energy costs compared to mesopelagic conspecifics but do not compensate with higher-energy prey. Fatty acid analysis revealed significant differences in blubber profiles between the two foraging types (global R = 0.30, p = 0.001), indicating divergent prey resource use despite overlapping diet components. Quantitative fatty acid signature analysis further confirmed distinct dietary contributions (global R = 0.17, p = 0.022). The study suggests that benthic foraging may represent a trade-off between increased energy expenditure and reduced competition with trawling fisheries, highlighting the ecological adaptability of this species in the New Zealand Sub-Antarctic Islands.

Meynier, L., Morel, P. C. H., Chilvers, B. L., Mackenzie, D. D. S., & Duignan, P. J. (2014). Foraging diversity in lactating New Zealand sea lions: insights from qualitative and quantitative fatty acid analysis. Canadian Journal of Fisheries and Aquatic Sciences, 71(7), 984–991. https://doi.org/10.1139/cjfas-2013-0479