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Lactating New Zealand (NZ) sea lions (Phocarctos hookeri) exhibit different foraging patterns during their foraging trips, with benthic divers spending more energy at sea than mesopelagic conspecifics. We compared blubber fatty acids (FAs) of 14 benthic and 12 mesopelagic females captured at the Auckland Islands, NZ subantarctic, in late January 2000 using an analysis of similarities (ANOSIM). FA profiles between foraging types were significantly different (global R = 0.30, p = 0.001), suggesting a different use in prey resources. We then compared the diet predictions by quantitative FA signature analysis (QFASA) by using a prey FA library available in the region. Overall, diet predictions were significantly distinct between benthic and mesopelagic females (global R = 0.17, p = 0.022), although the diets consisted of the same prey but in different contributions. The results suggest benthic females do not compensate their higher foraging costs by feeding on prey with higher energy densities. Foraging areas of benthic females are not exploited by the trawling fishery; therefore, the benthic tactic might be a trade-off between a higher foraging cost and less resource competition. Les lionnes de mer de Nouvelle Zelande (NZ) lactantes utilisent des tactiques de chasse en mer differentes: les individus chassant sur le benthos depensant plus d'energie que les individus mesopelagiques. Nous avons compare avec une ANOSIM les acides gras (AG) du lard de 14 lionnes de mer benthiques et 12 mesopelagiques capturees aux Iles Auckland (region subantarctique de la NZ) fin janvier 2000. Les profiles d'AG entre les comportements de chasse presentent des differences significatives (global R = 0.30, p = 0.001), probablement dues a une utilisation differente des ressources entre ces deux groupes. La composition du regime alimentaire a ete estimee par l'analyse quantitative des profiles d'AG (QFASA), en utilisant un catalogue d'AG de proies venant de la meme region. Les regimes alimentaires des deux types de chasse comprennent les memes especes de proies mais avec des proportions significativement differentes (global R = 0.17, p = 0.022). Il semble donc que les femelles chassant sur le benthos ne compensent pas leurs depenses energetiques plus elevees en mer par des proies de qualite superieure. Les zones de chasse des femelles benthiques ne sont pas exploitees par les pecheries; ces individus pourraient chercher un compromis entre une depense energetique elevee et une competition faible pour la ressource., Introduction The distribution and abundance of prey are major drivers in the foraging behavior of individuals (Costa 1993). Lactating otariids display a 'central place foraging' strategy during lactation because they [...]

We used quantitative fatty acid signature analysis (QFASA) to predict the long-term diet of New Zealand (NZ) sea lions (Phocarctos hookeri) incidentally caught in the NZ arrow squid (Nototodarus spp.) fishery. The QFASA model used fatty acid (FA) profiles based on 82 blubber samples of NZ sea lions bycaught between 2000 and 2006. First, the model was optimized by a series of simulations for which 1 model parameter--6 different sets of calibration coefficients (CCs) from different pinniped species and feeding regime, 2 sets of FAs, and the consideration of individual prey values, or mean prey values--varied each time. The best-fit parameters were those giving the lowest Kullback--Liebler distance values. Second, these parameters were used in a model to estimate the diet of NZ sea lions. QFASA was highly sensitive to the set of CCs applied. Across years the most important prey estimated with the best-fit CCs were southern arrow squid (Nototodarus sloani, 18-28% mass), hoki (Macruronus novaezelandiae, 10-27% mass), rattails (Macrouridae, 7-27% mass), and possibly scampi (Metanephrops challengeri, 1-19% mass). Despite the uncertainty on the accuracy of the match between the best-fit CCs used and the true FA metabolism of NZ sea lions, the variation of prey estimated among years was highly consistent with the trends of commercial catches during the same period, providing some confidence in the present QFASA predictions. The most important estimated prey were demersal species living mainly at depths >200 m that NZ sea lions encounter on the slopes of the Auckland Islands shelf. Our study emphasized the importance of these areas for bycaught NZ sea lions over the 1st half of the lactation period. DOI: 10.1644/09-MAMM-A-299.1. Key words: dietary methods, feeding ecology, pinniped

Recent research has revealed a neuroendocrine connection between the skeleton and metabolism. Exercise alters both bone modeling and energy balance and may be useful in further developing our understanding of this complex interplay. However, research in this field requires an animal model of exercise that does not cause a physiological stress response in the exercised subjects. In this study, we develop a model of short-term voluntary exercise in the female rat that causes bone modeling without causing stress. Rats were randomly assigned to one of three age-matched groups: control, tower climbing, and squat exercise (rising to an erect bipedal stance). Exercise for 21 days resulted in bone modeling as assessed by peripheral quantitative computed tomography. Fecal corticosterone output was used to assess physiological stress at three time points during the study (preexercise, early exercise, and late in the exercise period). There were no differences in fecal corticosterone levels between groups or time points. This model of voluntary exercise in the rat will be useful for future studies of the influence of exercise on the relationship between skeletal and metabolic health and may be appropriate for investigation of the developmental origins of those effects. computed tomography; corticosterone; exercise; metabolism; stress doi: 10.1152/ajpregu.00112.2010.