1. Individual specialization in the foraging behaviour of marine predators can affect the ecology, evolution, and ability of a population to respond to environmental variability and human impacts.
2. Here, blood serum and whisker stable isotope values from New Zealand (NZ) sea lion pups (Phocarctos hookeri) are compared with their mother’s values to identify whether they can be used as proxies to identify their mother’s isotopic niche and foraging strategy.
3. Female NZ sea lions have been identified, both through telemetry and stable isotope research of blood serum and whiskers, to have two distinct foraging ecotypes (mesopelagic or benthic), consistent across their adult life. Females who are mesopelagic foragers have higher overlap and a greater risk of harmful interactions with fisheries.
4. Stable isotope analysis of adult females can be used to determine the proportion of the female population exposed to these detrimental interactions. However, the capture, restraint, and removal of a whisker or blood from an adult female NZ sea lion is an expensive, time-consuming, and invasive undertaking. Instead, by comparing the blood serum and whisker δ¹³C and δ¹⁵N values of 12 NZ sea lion mother-and-pup pairs, for whom the foraging behaviour of the female is known, the question as to whether a pup’s blood serum or whisker isotope value can be used as a proxy to identify female foraging ecotype was investigated.
5. The δ¹³C and δ¹⁵N values for the blood serum and whiskers of pups and their mothers were correlated and differed significantly between foraging ecotypes. This research validates that pup blood serum and whisker stable isotope values from 1-month-old pups can be used as indicators of female isotopic niche and therefore foraging ecotype.
6. This tool can be used across all NZ sea lion colonies to indicate female NZ sea lion foraging ecotypes. For the Auckland Islands, it could determine the proportion of breeding females exposed to negative interactions with fisheries, leading to a better understanding of the level of these effects and helping to implement appropriate management to mitigate impacts.

中文翻译：

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通过幼须稳定同位素识别雌性觅食生态型和渔业影响

1. 海洋捕食者觅食行为的个体专业化会影响种群的生态、进化和应对环境变化和人类影响的能力。
2. 在这里，新西兰 (NZ) 海狮幼崽 ( Phocarctos hookeri ) 的血清和晶须稳定同位素值与其母亲的值进行了比较，以确定它们是否可以用作替代物来识别其母亲的同位素生态位和觅食策略。
3. 通过遥测和血清和胡须的稳定同位素研究，已确定雌性新西兰海狮具有两种不同的觅食生态型（中层或底栖），在其成年生活中保持一致。作为中层觅食者的雌性具有更高的重叠度，并且与渔业发生有害相互作用的风险更大。
4. 成年女性的稳定同位素分析可用于确定暴露于这些有害相互作用的女性人口的比例。然而，捕获、限制和去除成年雌性新西兰海狮的胡须或血液是一项昂贵、耗时且具有侵入性的工作。相反，通过比较已知雌性觅食行为的 12 对新西兰海狮母幼对的血清和晶须 δ ¹³ C 和 δ ¹⁵ N 值，问题是幼崽的血清或晶须同位素值可以作为确定雌性觅食生态型的代理进行了调查。
5. 幼崽及其母亲的血清和胡须的δ ¹³ C 和δ ¹⁵ N 值是相关的，并且在觅食生态型之间存在显着差异。该研究证实，来自 1 个月大幼崽的幼崽血清和晶须稳定同位素值可用作雌性同位素生态位的指标，因此可用作觅食生态型的指标。
6. 该工具可用于所有新西兰海狮群，以指示新西兰雌性海狮觅食生态型。对于奥克兰群岛，它可以确定与渔业产生负面影响的繁殖雌性的比例，从而更好地了解这些影响的程度，并有助于实施适当的管理以减轻影响。