Co-occurrence of gray whales and vessel traffic in the North Pacific Ocean

Abstract

All species of large whales are susceptible to vessel strikes, but the true scale and geographical extent of such strikes is not known. This paper provides a qualitative assessment of the range-wide risks posed to gray whales Eschrichtius robustus by vessels, by comparing patterns of whale distribution with the density of vessel traffic seasonally throughout the North Pacific in 2019. Areas of very high vessel density were evident year-round near many coastlines, along inter-continental trade routes, and at hubs of commercial shipping near port entrances. Gray whales were exposed to vessel strikes throughout their range and in their feeding, southbound migration, wintering, and northbound migration periods. Areas of apparently high risk were in the Russian Far East (Kamchatka peninsula and Okhotsk Sea), Bering Sea (including the Aleutian Islands), Gulf of Alaska, and along the entire west coast of North America. Risk appeared greatest during south- and northbound migration when much of the gray whale population is moving through waters near shore. Tanker, container, and bulk-carrier ships represent considerable risk to whales in the North Pacific Ocean, but the large geographical extent of commercial fishing activities suggests that fisheries are also a substantial source of risk. Vessel-strike risk maps indicate the relative extent of exposure of gray (and other) whales to underwater vessel noise. The number of gray whales killed by ship strikes each year may be in the tens, or perhaps the low hundreds. Additional analyses, including quantitative assessments, are warranted to further clarify the risk of vessel strikes to gray whales.

Gray whale density during seismic surveys near their Sakhalin feeding ground

“…Eastern gray whales have also been shown to respond to vessel activity in their breeding lagoons (Bryant et al, 1984 ). Gray whales are also likely exposed to heavy vessel traffic throughout their home range with the potential risk to their survival associated with ship strikes (Silber et al, 2021 ). Western gray whales have been observed to respond behaviorally to the proximity and sound levels of vessel activity in the study area (Gailey, 2013 ; Gailey et al, 2007 , 2016 , 2022 ).…”

“…Seismic surveys use air guns to map deposits beneath the seafloor. Marine seismic surveys and vessel traffic are major contributors to global ocean noise (Hildebrand, 2009 ; Nowacek et al, 2015 ; Silber et al, 2021 ) and have the potential to impact marine life (Carroll et al, 2017 ; Richardson et al, 1995 ; Southall et al, 2007 ; Weilgart, 2013 ).…”

Pairing AIS data and underwater topography to assess maritime traffic pressures on cetaceans: Case study in the Guadeloupean waters of the Agoa sanctuary

“…The analysis of AIS data spans nowadays, from vessel routing and operations to complex issues such as the interaction between maritime traffic and wildlife or monitoring environmental compliance (Fournier et al, 2018;Robards et al, 2016). With regard to the knowledge and conservation of cetaceans, AIS data are now commonly used alongside observation data of some species, mainly to assess collision risk and exposure to noise pollution generated by shipping (Chion et al, 2012;Guzman et al, 2013;Lagueux et al, 2011;McWhinnie etal., 2021;Priyadarshana et al, 2016;Silber et al, 2021). But for cetaceans, the effects of maritime traffic pressures are not limited to physical injuries (collisions, hearing loss) and extend to more complex advert impacts such as physiological stress (e.g., caused by the prolonged or often recurrent exposure to ship presence or to noise), the creation of barriers to their movement and communication (e.g., via masking) and the modification of their behaviour, e.g., reduced foraging, shift or decrease in social activities, with short and long-term consequences (e.g., Lusseau et al, 2009;Erbe et al 2019;Smith et al, 2020.…”

Important areas for cetaceans in Russian Far East waters

“…All types of activities with vessel traffic present the risk of vessel strike to cetaceans (Laist et al, 2001; Silber et al, 2021). The Bering and Chukchi seas are listed among the high‐risk areas where collisions between ships and whales can occur (Silber et al, 2021).…”

“…All types of activities with vessel traffic present the risk of vessel strike to cetaceans (Laist et al, 2001;Silber et al, 2021). The Bering and Chukchi seas are listed among the high-risk areas where collisions between ships and whales can occur (Silber et al, 2021). Vessel strikes have been shown to cause injuries and significant levels of mortality in some cetacean species (Mullen, Peterson & Todd, 2013;van der Hoop et al, 2015).…”