Identifying gray whale (Eschrichtius robustus) foraging grounds along the Chukotka Peninsula, Russia, using satellite telemetry

Abstract

The purpose of this study was to evaluate summer and fall residency and habitat selection by gray whales, Eschrichtius robustus, together with the biomass of benthic amphipod prey on the coastal feeding grounds along the Chukotka Peninsula. Thirteen gray whales were instrumented with satellite transmitters in September 2006 near the Chukotka Peninsula, Russia. Nine transmitters provided positions from whales for up to 81 days. The whales travelled within 5 km of the Chukotka coast for most of the period they were tracked with only occasional movements oVshore. The average daily travel speeds were 23 km day ¡1 (range 9-53 km day ¡1 ). Four of the whales had daily average travel speeds <1 km day ¡1 suggesting strong Wdelity to the study area. The area containing 95% of the locations for individual whales during biweekly periods was on average 13,027 km 2 (range 7,097-15,896 km 2 ). More than 65% of all locations were in water <30 m, and between 45 and 70% of biweekly kernel home ranges were located in depths between 31 and 50 m. Benthic density of amphipods within the Bering Strait at depths <50 m was on average »54 g wet wt m ¡2 in 2006. It is likely that the abundant benthic biomass is more than suYcient forage to support the current gray whale population. The use of satellite telemetry in this study quantiWes space use and movement patterns of gray whales along the Chukotka coast and identiWes key feeding areas.

Determining the species assemblage and habitat use of cetaceans in the Svalbard Archipelago, based on observations from 2002 to 2014

“…KDEs were calculated using the Kernel Density Analysis tool within ArcMap, with a search radius of 50 km and a cell size of 1 km, for each species with over 100 observations to display where each of the species were observed in this study (see Silverman 1986;Powell 2000). The 50 km search radius was used as a general daily displacement distance for cetaceans using foraging grounds (e.g., Hobbs et al 2005;Zerbini et al 2006;Dalla Rosa et al 2008;Heide-Jørgensen et al 2012;Kennedy et al 2014;Heide-Jørgensen et al 2015). The resulting KDEs were displayed using 10 quantiles.…”

Factors affecting whale detection from large ships in Alaska with implications for whale avoidance

“…Even when shifts in shipping lanes are used, they may result in a reduction, but not elimination, of the risk of ship−whale encounters as whale aggregations may shift within and among years with shifts in prey or oceanographic conditions (e.g. Witteveen et al 2008, Chenoweth et al 2011, Becker et al 2012, Doniol-Valcroze et al 2012, Heide-Jørgensen et al 2012, Keller et al 2012, Pendleton et al 2012, Gregr et al 2013.…”

Site-fidelity and spatial movements of western North Pacific gray whales on their summer range off Sakhalin, Russia

“…Satellite-tags deployed on WNP individuals [29,30] and genetic and photo-ID comparisons between ENP and WNP individuals [31][32][33][34][35] demonstrated that at least a portion of the WNP whales migrated to Baja California. This indicated some degree of spatial overlap between the two populations, as ENP whales typically migrate from breeding grounds near Baja California to summer foraging areas in the Bering and Chukchi Seas [36][37][38][39]. However, genetic studies have consistently found significant differentiation, with some limited genetic exchange occurring [31,32,38,[40][41][42][43][44].…”