Spatial distribution of Antarctic minke whales (Balaenoptera bonaerensis) in relation to spatial distributions of krill in the Ross Sea, Antarctica

Abstract

The spatial distribution of Antarctic minke whales in the Ross Sea with relation to spatial distributions of their prey – krill – was investigated in this study using generalized additive models (GAMs). Spatial distributions of two species of krill (ice and Antarctic krill) were estimated by GAMs. Three abiotic factors – distance from the continental shelf break (800 m isobaths), the mean temperature and salinity from the surface to 200 m (MTEM‐200 and MSAL‐200), and latitude and longitude – were used as covariates for models of krill. Estimated spatial distributions of krill were then used with other covariates to model the spatial distribution of Antarctic minke whales. In the selected model of Antarctic minke whales, Antarctic krill were more influential than ice krill. The number of Antarctic minke whales increased as the density of Antarctic krill increased to around 1.5 g m−2. Beyond that, the number of Antarctic minke whales decreased as the density of Antarctic krill increased. High densities of the Antarctic minke whales were estimated along the sea ice edge in the eastern part of the Ross Sea. Specifically, the densities were high in the north of the continental shelf break where low MTEM‐200 and MSAL‐200 and intermediate densities of Antarctic krill were observed. Further data collection is needed to investigate interannual variations and trends in their relationship. The results show that the spatial distribution of Antarctic minke whales is a function of longitude, distance from the shelf break, oceanographic condition (temperature and salinity), and densities of ice and Antarctic krill.

Distributions of krill and Antarctic silverfish and correlations with environmental variables in the western Ross Sea, Antarctica

“…For the Antarctic marine system, species distribution models have focused on Antarctic krill and top predators because of their importance in the food web, and the availability of observations to describe the distributions and habitat characteristics (Ichii 1990, Trathan et al 2003, Naganobu et al 2006 al. , Murase et al 2013.…”

Behavior of satellite-tracked Antarctic minke whales (Balaenoptera bonaerensis) in relation to environmental factors around the western Antarctic Peninsula

“…The association of minke whales with sea ice, the southern boundary of the Antarctic Circumpolar Current, and the shelf break is likely due to high prey abundances, particularly Antarctic krill (Euphausia superba) and ice krill (Euphausia crystallorophias) [14,39]. Antarctic minke whale foraging behavior is characterized by high feeding rates, defined by the number of feeding lunges per dive, compared to larger baleen whales [24].…”

How biological clocks and changing environmental conditions determine local population growth and species distribution in Antarctic krill (Euphausia superba): a conceptual model

“…Species distribution models for krill identified abiotic factors such as distance from continental shelf break, water temperature, and water salinity to be important (Murase et al, 2013). Biotic factors have also been suggested to determine the habitat distribution of krill such as food availability (Hill et al, 2013) and competing species (Loeb et al, 1997).…”