Depredating sperm whales in the Gulf of Alaska: local habitat use and long distance movements across putative population boundaries

Abstract

Satellite tags were attached to 10 sperm whales Physeter macrocephalus (1 whale was tagged in 2 different years) to determine the movements of sperm whales involved in removal of sablefish from longline fishing gear in the Gulf of Alaska (GOA). Tags , respectively). Tagged sperm whales primarily travelled over the slope, but one spent considerable time over the ocean basin. Information on the timing and movement patterns of sperm whales may provide a means for fishermen to avoid fishing at whale hot spots, potentially reducing interactions between whales and fishermen.

When large marine predators feed on fisheries catches: Global patterns of the depredation conflict and directions for coexistence

“…In some regions, the use of satellite tagging increased knowledge on preferred areas of predators, and therefore, on areas where fishers were the most likely to be subject to depredation (e.g. Cronin, Gerritsen, Reid, & Jessopp, 2016;Oksanen, Niemi, Ahola, & Kunnasranta, 2015;Stepanuk, Read, Baird, Webster, & Thorne, 2018;Straley et al, 2014;Thorne, Baird, Webster, Stepanuk, & Read, 2019). Move-on practices, although commonly used by fishers, were shown effective only when vessels travelled distances sufficiently large to reduce the chances of being actively followed by predators (Forney, Kobayashi, Johnston, Marchetti, & Marsik, 2011;Janc et al, 2018;Tixier et al, 2018;Tixier, Vacquie Garcia, Gasco, Duhamel, & Guinet, 2015).…”

“…Instances of collective interdisciplinary research were highlighted in scientific programs on depredation involving biologists and fishery scientists, but also cross‐sectoral (transdisciplinary) collaborations with industry representatives (fishers, companies, gear suppliers, etc.). These programs, found for example in South Africa (Wickens et al, 1992), Alaska (Straley et al, 2015), the UK (Butler et al, 2008), the Baltic Sea (Bruckmeier & Larsen, 2008; Westerberg et al, 2008) and in the Southern Ocean (Guinet et al, 2015), have led to major advances on both the understanding and the mitigation of the conflict and, therefore, should be further developed across other depredation situations.…”

Demography or selection on linked cultural traits or genes? Investigating the driver of low mtDNA diversity in the sperm whale using complementary mitochondrial and nuclear genome analyses

“…Among toothed whales, however, unusually low mitochondrial DNA (mtDNA) diversity in some of the social odontocetes (e.g., sperm, pilot, killer and false‐killer whales; Alexander et al., , ; Hoelzel et al., ; Martien et al., ; Van Cise et al., ) has limited power to infer population structure, phylogeography and historical demography using traditional genetic tools. The sperm whale ( Physeter macrocephalus ) is particularly enigmatic in this respect, as it is one of the most cosmopolitan and abundant of the large odontocetes, and known to move over large ranges of up to thousands of kilometres over annual or longer time periods (Mizroch & Rice, ; Steiner et al., ; Straley et al., ), yet it exhibits low mtDNA diversity and evidence of female philopatry (Alexander et al., ; Lyrholm & Gyllensten, ; Lyrholm, Leimar, Johanneson, & Gyllensten, ; Mesnick et al., ).…”

Evidence for dietary time series in layers of cetacean skin using stable carbon and nitrogen isotope ratios

“…It must be noted that sperm whales have a higher trophic level than species in these studies; thus, the inner layer would not be an ideal tissue to infer baseline shifts because trophic discrimination probably obscures changes in baseline patterns. In addition, while male sperm whales are generally thought to move to GOA waters in the spring and summer months, no pattern exists for sperm whale departures from Alaskan waters, suggesting that arrivals are similarly non‐patterned. Shifting prey species between regions could also explain changes in stable isotope ratios, as sperm whales in the eastern GOA are known to consume more deep sea fish than squid, unlike other regions off the western coast of North America where squid is the primary diet item .…”