Researchers report Sitka (Sika) Sound mass-gain and a surge of feeding grey whales

Researchers presenting at a Marine Mammal Commission symposium described unusually large aggregations of grey whales feeding in Sitka (Sika) Sound and preliminary energy-balance modeling that suggests substantial mass gain over short residencies.

Andy Zabo of the Alaska Whale Foundation summarized a multi-team effort that documented roughly 250 grey whales using Sika Sound over two seasons and a peak single-day count near 171 animals. "We found that the grey whales over their average 20-day residency in that area are putting on about 100 kg of blubber a day," he said, describing a mass-acquisition model being developed with collaborators. Panelists said that scale of daily energy intake could be two-to-three times what similar models estimate for humpback or bowhead whales under comparable conditions.

Speakers noted the timing: Sitka Sound peaks roughly two weeks after local herring spawn and weeks after commercial fishery activity. That temporally buffered window, panelists said, appears to attract both PCFG (Pacific Coast Feeding Group) and other ENTP migrants in varying proportions. Lauren Wild (University of Alaska Southeast, Sitka) said this site has seen a dramatic rise since about 2019, with their largest single-day count at 176 this season.

Panelists cautioned the numbers reflect intensive short-season effort (March–May) and that mass-gain estimates remain model-based and under refinement. They emphasized continued photo-identification, drone-based photogrammetry and tag-based tracking to verify how many whales feed, how long they stay, and whether individuals later reach Arctic foraging areas.