AMLR 2009/10 Field Season Report: objectives, accomplishments and conclusions

The U.S. Antarctic Marine Living Resources (U.S. AMLR) field season completed it’s 24th season of a long-term series of studies of the Antarctic Peninsula ecosystem. Hydrographic results characterizing the waters around the South Shetland Islands indicate that several water masses converge in the area, forming a front along the shelf break north of the archipelago. During the 2009/10 U.S. AMLR Survey in the South Shetland Islands, acoustic estimates of krill biomass were the lowest seen since 2006; the results will be recalculated based on updated models from the 2010 CCAMLR WG-ASAM. Net-based estimates of krill abundance also decreased, for the second consecutive year, and recruitment indices were low, indicating that a weak cohort was produced the previous year. The abundance of Salpa thompsoni was greater this year than the last ten years. The production of penguin chicks decreased compared to the 2008/09 breeding season; gentoo penguins produced 16% fewer than the 12-year mean, while chinstrap penguins produced 41% less than the 12-year mean. Antarctic fur seals pup production decreased for the third consecutive year during the 2009/10 austral summer. Foraging trips by female fur seals decreased in length midway through the breeding season, and increased again toward the end of the season. Mortality of neonate fur seals increased compared to the prior year, and 69% of pups were lost to leopard seal predation. (AMLR 2009/2010 Field Season Report: Objectives, Accomplishments and Conclusions. NOAA Technical Memorandum, NOAA-TM-NMFS (in press))