The integrated modeling framework for Antarctic krill (Euphausia superba) has been extended to include estimates of krill growth consistent with survey data and to use multi-nation survey data collected from 1981 to 2014 near the Antarctic Peninsula. Four models of the population dynamics of Antarctic krill in Subarea 48.1 based on different aggregations of the data are described to illustrate the capabilities of the framework.
Calibrated, integrated, and averaged acoustics data, including estimates of krill (Euphausia superba) biomass density, collected around Elephant Island, the South Shetland Islands, and the Antarctic Peninsula by the U.S. AMLR Program. Data are integrated over depths from about 10-15m down to the bottom or 250m (whichever is shallower) and averaged over 1-nmi intervals.
An integrated, age-structured model was fitted to different combinations of survey data using two forms of selectivity (logistic or double-logistic) with time-constant or annually varying selectivity to investigate the population dynamics of Antarctic krill (Euphausia superba) near the Antarctic Peninsula. The
data were from surveys conducted by the U.S. Antarctic Marine Living Resources Program around the South Shetland Islands from 1992 to 2011. Two indices of krill biomass based on (1) trawl-net samples and (2) hydroacoustic sampling were combined with length-compositions from the nets. Sixteen model
configurations using different combinations of the two biomass surveys with the various options for modeling selectivities were examined.