It may be the little things that determine whether whales and salmon survive

It may be the little things that determine whether whales and salmon survive

Source: The Olympian

2/13/2022

It may be the little things that determine whether whales and salmon survive

Credit: Cheryl Nelson

To understand the plight of Puget Sound whales and salmon, we need to know more about the tiniest creatures in the water — the zooplankton and phytoplankton that comprise the base of the marine food web.

“Anything that comes out of the ocean is eating something that eats zooplankton, or eating zooplankton directly,” says Phillip Dionne, senior research scientist at the Washington Department of Fish and Wildlife. And the zooplankton (tiny animals) mostly eat phytoplankton (tiny plants).

Juvenile salmon swimming into Puget Sound from their natal rivers depend on zooplankton. These small, hungry fish need little bites that fit in their little mouths.

When juvenile salmon get big enough to fit a herring in their mouth, it’s not always certain there will be herring around for them to eat. Herring populations, says Julie Keister, a University of Washington oceanographer, have been “a roller coaster.” A couple of years with higher-than-usual ocean temperatures seems to have boosted herring numbers, but before that there was acute worry over their decline.

Herring eat zooplankton. But at this point, it’s not known whether there’s a relationship between the health and abundance of any of the many species of zooplankton and herring populations.