Approximating home ranges of humpback and fin whales in Drake Passage and Antarctica

Abstract

Identifying home ranges—those areas traversed by individuals in their normal foraging, mating, and parenting activities—is an important aspect of cetacean study. Understanding these ranges facilitates identification of resource use and conservation. Fin and humpback whales occur in Antarctica during the austral summer, but information regarding their home ranges is limited. Using opportunistically collected whale sighting data from eight consecutive summer seasons spanning 2010–2017, we approximate the home ranges of humpback and fin whales around Drake Passage (DRA), West of Antarctic Peninsula (WAP), South Shetland Islands (SSI), an area northwest of the Weddell Sea (WED), and around the South Orkney Islands (SOI). Approximate home ranges are identified using Kernel Density Estimation (KDE). Most fin whales occurred north and northwest of the SOI, which suggests that waters near these islands support concentrations of this species. Most humpback whales were observed around the SSI, but unlike fin whales, their distributions were highly variable in other areas. KDE suggests spatial segregation in areas where both species exist such as SOI, SSI, and WPA. Partial redundancy analysis (pRDA) suggests that the distributions of these species are more affected by spatial variables (latitude, longitude) than by local scale variables such as sea surface temperature and depth. This study presents a visual approximation of the home ranges of fin and humpback whales, and identifies variation in the effects of space and environmental variables on the distributions of these whales at different spatial scales. Citation: Orgeira J L, Alvarez F. Approximating home ranges of humpback and fin whales in Drake Passage and Antarctica. Adv Polar Sci, 2020, 31(4): 248-257, doi: 10.13679/j.advps.2020.0014