Alaska and Hawaii are about as different as two states get โ one icy, one tropical. Plenty of humpback whales spend the year in both of them.
In summer, humpback whales of the North Pacific feed in cold northern water, including the seas around Alaska, where the food they filter out of the water is thick.
Basis: NOAA Fisheries: North Pacific humpback whales feed in cold high-latitude waters, including Alaska, during summer.
In winter, many of those same whales swim thousands of miles to the warm, shallow water around the Hawaiian Islands. That is where they breed and where their calves are born โ and while they are there they mostly do not eat.
Basis: NOAA Fisheries and the Hawaiian Islands Humpback Whale National Marine Sanctuary: humpbacks migrate to Hawaii in winter to breed and calve, and fast through that season.
How do we know it is the same whales? The underside of a humpback's tail has a pattern as individual as a fingerprint. Researchers photograph it, and the pictures have matched whales seen off Alaska with whales seen off Hawaii.
Basis: NOAA Fisheries: humpbacks are identified individually by fluke photographs, and basin-wide North Pacific photo-identification work (the SPLASH study, 2004โ2006) matched individual whales between northern feeding areas such as Alaska and winter breeding areas such as Hawaii.
Why swim that far to a place with almost nothing to eat? Warm, calm, shallow water may be a safer nursery for a newborn calf with hardly any blubber. It is the usual explanation โ but scientists are still arguing about what really drives the trip.
โป A hypothesis is an idea that isn't proven yet.
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