Abstract
In the Antarctic Peninsula, during the chick-rearing period Adélie (Pygoscelis adeliae) and gentoo (P. papua) penguins feed primarily on Antarctic krill (Euphausia superba), which is also exploited by the commercial fishery. Krill length and proportion of juvenile krill consumed by these predators that breed at Stranger Point, South Shetland Islands (from 2007/2008 to 2015/2016), and those collected by the krill fishery in the Mar de la Flota/Bransfield Strait (from 2009/2010 to 2015/2016) were compared to evaluate the potential of each data source as an indicator of changes in the size composition and so, in the demographic structure of the krill population. Overall, the mean krill size taken by gentoo penguins was larger than that ingested by Adélie penguins, which consumed higher proportions of juvenile (≤ 35 mm) and one-year-old (≤ 25 mm) krill. Although the krill size caught by the fishery was statistically similar to that taken by both penguin species, there were differences in the frequency distributions of krill size among the three databases. Furthermore, when only adult krill (> 35 mm) was considered, the three sources of krill data showed a similar inter-annual variation in the availability of adult krill cohorts. Our findings suggest that each database analysed here can potentially provide different information (although complementary) about krill size composition. In addition, inter-annual fluctuations in the smaller size classes of krill likely reflect their first year of recruitment and, therefore, may be used as an indicator of shifts in local krill availability.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.