Evidence of resource partitioning between humpback and minke whales around the western Antarctic Peninsula

Abstract

For closely related sympatric species to coexist, they must differ to some degree in their ecological requirements or niches (e.g., diets) to avoid interspecific competition. Baleen whales in the Antarctic feed primarily on krill, and the large sympatric prewhaling community suggests resource partitioning among these species or a nonlimiting prey resource. In order to examine ecological differences between sympatric humpback and minke whales around the Western Antarctic Peninsula, we made measurements of the physical environment, observations of whale distribution, and concurrent acoustic measurements of krill aggregations. Mantel's tests and classification and regression tree models indicate both similarities and differences in the spatial associations between humpback and minke whales, environmental features, and prey. The data suggest (1) similarities (proximity to shore) and differences (prey abundance versus deep water temperatures) in horizontal spatial distribution patterns, (2) unambiguous vertical resource partitioning with minke whales associating with deeper krill aggregations across a range of spatial scales, and (3) that interference competition between these two species is unlikely. These results add to the paucity of ecological knowledge relating baleen whales and their prey in the Antarctic and should be considered in conservation and management efforts for Southern Ocean cetaceans and ecosystems.

Trophic cascades in the western Ross Sea, Antarctica: revisited

“…Friedlaender et al 2014). The depth of minke whale foraging is certainly affected by the depth of their prey and appeared to average well within our prey sampling zone to 90 m (Friedlaender et al 2014), even if the depth at which prey (krill) aggregate in the presence of whales becomes deeper (Friedlaender et al 2009). Unfortunately, the low den sity of the glider tracks precluded our ability to assess how mesopredator foraging might have altered the size and shape of prey schools/ swarms.…”

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

“…This provides an indication of a horizontal niche separation between the two species. As suggested by Friedlaender et al (2009) for Antarctic minke whales and humpback whales, sympatric whale species feeding on krill may have evolved some form of resource partitioning mechanism to avoid interspecific competition for prey. In the case of Antarctic minke whales and humpback whales, both species prefer coastal habitats on the shelf of the AP region (Friedlaender et al 2009).…”

“…As suggested by Friedlaender et al (2009) for Antarctic minke whales and humpback whales, sympatric whale species feeding on krill may have evolved some form of resource partitioning mechanism to avoid interspecific competition for prey. In the case of Antarctic minke whales and humpback whales, both species prefer coastal habitats on the shelf of the AP region (Friedlaender et al 2009). They appear to feed on krill in different depth ranges in the water column, indicating vertical niche segregation (Friedlaender et al 2006(Friedlaender et al , 2009.…”

“…In the case of Antarctic minke whales and humpback whales, both species prefer coastal habitats on the shelf of the AP region (Friedlaender et al 2009). They appear to feed on krill in different depth ranges in the water column, indicating vertical niche segregation (Friedlaender et al 2006(Friedlaender et al , 2009. The results of our study suggest a horizontal niche separation between humpback and fin whales, with humpback whales preferring the coastal parts of BS and fin whales residing in habitats around the shelf edge in DP.…”

“…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). For example, recurrent and tidally predictable availability of krill occurrence has been shown to make areas highly attractive for whales (Cotté and Simard 2005).…”