Abstract
Six baleen whale species are found in the temperate western North Atlantic Ocean, with limited information existing on the distribution and movement patterns for most. There is mounting evidence of distributional shifts in many species, including marine mammals, likely because of climate‐driven changes in ocean temperature and circulation. Previous acoustic studies examined the occurrence of minke (Balaenoptera acutorostrata) and North Atlantic right whales (NARW; Eubalaena glacialis). This study assesses the acoustic presence of humpback (Megaptera novaeangliae), sei (B. borealis), fin (B. physalus), and blue whales (B. musculus) over a decade, based on daily detections of their vocalizations. Data collected from 2004 to 2014 on 281 bottom‐mounted recorders, totaling 35,033 days, were processed using automated detection software and screened for each species' presence. A published study on NARW acoustics revealed significant changes in occurrence patterns between the periods of 2004–2010 and 2011–2014; therefore, these same time periods were examined here. All four species were present from the Southeast United States to Greenland; humpback whales were also present in the Caribbean. All species occurred throughout all regions in the winter, suggesting that baleen whales are widely distributed during these months. Each of the species showed significant changes in acoustic occurrence after 2010. Similar to NARWs, sei whales had higher acoustic occurrence in mid‐Atlantic regions after 2010. Fin, blue, and sei whales were more frequently detected in the northern latitudes of the study area after 2010. Despite this general northward shift, all four species were detected less on the Scotian Shelf area after 2010, matching documented shifts in prey availability in this region. A decade of acoustic observations have shown important distributional changes over the range of baleen whales, mirroring known climatic shifts and identifying new habitats that will require further protection from anthropogenic threats like fixed fishing gear, shipping, and noise pollution.
Highlights
Seasonal migratory patterns are the foundation of long-distance movements and dramatic changes in animal distribution for many taxa in the animal kingdom (Dingle, 2014)
Additional studies reveal bottom-up effects of temperature changes, such as shifts in kelp distribution (Merzouk & Johnson, 2011) and collapses of fisheries (Pershing et al, 2015), eventually leading to changes in communities within the entire marine ecosystems (Beaugrand et al, 2019). It is unclear whether other North Atlantic baleen whale species have undergone similar shifts in their movement patterns to North Atlantic right whales (NARW) in response to ocean warming and food source redistribution
This is the first study to show spatial and temporal occurrence of humpback, fin, blue, and sei whales across the western North Atlantic Ocean over long time spans and large spatial scales and to demonstrate how these species' distributions have changed over time
Summary
Seasonal migratory patterns are the foundation of long-distance movements and dramatic changes in animal distribution for many taxa in the animal kingdom (Dingle, 2014). Additional studies reveal bottom-up effects of temperature changes, such as shifts in kelp distribution (Merzouk & Johnson, 2011) and collapses of fisheries (Pershing et al, 2015), eventually leading to changes in communities within the entire marine ecosystems (Beaugrand et al, 2019) It is unclear whether other North Atlantic baleen whale species have undergone similar shifts in their movement patterns to NARWs in response to ocean warming and food source redistribution. Blue whales are found from southern Newfoundland to the Davis Strait (Mansfield, 1985), while acoustic detections indicate their presence as far south as the New York Bight and near the Mid-Atlantic Ridge (Muirhead et al, 2018; Nieukirk et al, 2004) They are seen and heard year-round outside the Gulf of St. Lawrence in waters off Nova Scotia (Moors-Murphy et al, 2019). North Atlantic Ocean, and to determine whether any of these species exhibited similar shifts in distribution patterns across time
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