Modeling the spatial and temporal dynamics of foraging movements of humpback whales (Megaptera novaeangliae) in the Western Antarctic Peninsula

Abstract

BackgroundA population of humpback whales (Megaptera novaeangliae) spends the austral summer feeding on Antarctic krill (Euphausia superba) along the Western Antarctic Peninsula (WAP). These whales acquire their annual energetic needs during an episodic feeding season in high latitude waters that must sustain long-distance migration and fasting on low-latitude breeding grounds. Antarctic krill are broadly distributed along the continental shelf and nearshore waters during the spring and early summer, and move closer to land during late summer and fall, where they overwinter under the protective and nutritional cover of sea ice. We apply a novel space-time utilization distribution method to test the hypothesis that humpback whale distribution reflects that of krill: spread broadly during summer with increasing proximity to shore and associated embayments during fall.ResultsHumpback whales instrumented with satellite-linked positional telemetry tags (n = 5), show decreased home range size, amount of area used, and increased proximity to shore over the foraging season.ConclusionsThis study applies a new method to model the movements of humpback whales in the WAP region throughout the feeding season, and presents a baseline for future observations of the seasonal changes in the movement patterns and foraging behavior of humpback whales (one of several krill-predators affected by climate-driven changes) in the WAP marine ecosystem. As the WAP continues to warm, it is prudent to understand the ecological relationships between sea-ice dependent krill and krill predators, as well as the interactions among recovering populations of krill predators that may be forced into competition for a shared food resource.

Mid-summer abundance estimates of fin whales Balaenoptera physalus around the South Orkney Islands and Elephant Island

“…However, since the 2 surveys took place in 2 different years, it cannot be discerned from this study whether high fin whale densities occur area-wide throughout the full range of the suggested high-density area simultaneously or if aggregations of fin whales shift within the area. As highly mobile oceanic predators, whales are known to move dynamically with their prey (Santora et al 2014, Curtice et al 2015, possibly leading to temporal hot spot occurrences of fin whales throughout the suggested high-density area. Further studies are needed to characterise the spatio-temporal distribution, movements and habitat use of aggregating fin whales within the area.…”

Horizontal niche partitioning of humpback and fin whales around the West Antarctic Peninsula: evidence from a concurrent whale and krill survey

“…different species models can only be compared between models for the same species); dev.exp is a measure of how much of the observed values are predicted by the model (the higher the value, the more of variation is explained) The best models, given in bold, were chosen based on REML score and explained deviance hence more whales on the track line are missed. Moreover, humpback whales have been shown to be highly mobile around the WAP and to move in and out of the BS (Curtice et al 2015). Therefore, variation in abundance at any observed time can be expected.…”

“…Krill at the WAP undergo seasonal variations in distribution and abundance (Siegel 1988;Lascara et al 1999) which is influencing the distribution and abundance of the predators preying on them (Curtice et al 2015). Several studies suggest that whales might be able to identify physical features of the ocean that may lead them towards enriched prey abundances (Murase et al 2002;Friedlaender et al 2006Friedlaender et al , 2009Santora et al 2014).…”

Migratory preferences of humpback whales between feeding and breeding grounds in the eastern South Pacific

“…In addition, historical and recent studies provide evidence that humpback whales from the BSG can reach a latitudinal extent of up to 69°S (Rayner , Curtice et al . ), between 73°W (Rayner ) and 110°W (Mackintosh ) in the western extension, and up to 40°W (Dalla Rosa et al . ) and as far as 27°W in more eastward areas (Castro et al .…”