First evidence for fin whale migration into the Pacific from Antarctic feeding grounds at Elephant Island

Abstract

This study presents the first long-distance tracks of fin whales ( Balaenoptera physalus ) equipped with satellite transmitters off the Antarctic Peninsula. Southern Hemisphere fin whales were severely depleted by twentieth century industrial whaling, yet recently, they have returned to historical feeding grounds off the northern Antarctic Peninsula, forming large aggregations in austral summers. To date, our knowledge only extended to summer behaviour, while information regarding migration routes and the location of breeding and wintering grounds are lacking. During the austral autumn of 2021, we deployed nsatellite transmitters on four fin whales at Elephant Island. Two transmitters stopped working while the animals were still at the feeding grounds, while two continued to transmit during the transition from feeding activity to migration. Both migrating animals left the feeding ground on 15 April 2021, travelling northward into the Pacific and up along the Chilean coast. The most northerly position received before all tags stopped transmitting on 1 May 2021 was at 48°S. These tracks provide initial evidence of seasonal migratory routes and a first indication toward possible locations of winter destinations. This information, even if preliminary, is critical for investigations of population connectivity, population structure and the identification of breeding grounds of Southern Hemisphere fin whales.

Historical baleen plates indicate that once abundant Antarctic blue and fin whales demonstrated distinct migratory and foraging strategies

“…This historical evidence for foraging outside the Southern Ocean can be compared to contemporary observations. Antarctic blue and fin whales have been acoustically and visually detected in numerous highly productive areas in temperate regions outside of the Southern Ocean in recent decades including southern Australia (Aulich et al., 2019 ; Gill, 2002 ), Madagascar (Samaran et al., 2013 ), Chile (Herr et al., 2022 ; Sepulveda et al., 2018 ; Thomisch et al., 2016 ), and other locations throughout the southern Indian and Pacific Oceans as far north as 15° S (Balcazar et al., 2017 ) and evidence points to foraging behavior there. In contrast, as mentioned previously, acoustic detections of some blue whales have occurred year‐round in the Southern Ocean (Double et al., 2013 ; Širović et al., 2009 ) although virtually nothing is known about the prevalence of overwintering in this location, or potential foraging through winter months.…”

Report of the Scientific Committee

“…The Committee reviewed the first long-distance tracks of two fin whales equipped with satellite transmitters off the Antarctic Peninsula (Herr et al, 2022b). Both migrating animals left the feeding grounds on 15 April 2021 and travelled northward into the Pacific and up along the Chilean coast, providing the first evidence of seasonal migratory routes toward over-wintering grounds.…”

Pack-ice seals contribute to biological transfers of iron in the Southern Ocean

“…These areas are also targeted by other megafauna taxa, i.e. penguin colonies and aggregations of feeding whales (Herr et al 2022). As all individuals take advantage of the increased productivity, they synchronously participate in maintaining iron levels in the euphotic zone when conditions are favourable for primary producers.…”