Unusually warm ocean conditions off the Pacific Northwest in the last few years led anchovies, sardines and hake to begin spawning in Northwest waters much earlier in the year and, for anchovy, longer than biologists have ever recorded before, new research has found.
The rapid northerly shifts in spawning may offer a preview of future conditions if ocean warming continues, according to the new study published in Global Change Biology by scientists from the Pacific States Marine Fisheries Commission, Oregon State University and NOAA Fisheries’ Northwest Fisheries Science Center.
Some species may spend less time in southern waters off California, where anchovy and sardines have been less prevalent in recent years, and more of the year off the Northwest, the authors suggest. From 2015 to 2016 researchers found the highest concentrations of sardine, anchovy and hake larvae in the Northern California Current, off the Pacific Northwest, than they have in any year since collections began in 1998.
“Changes in spawning timing and poleward migration of fish populations due to warmer ocean conditions or global climate change will negatively affect areas that were historically dependent on these fish, and change the food web structure of the areas that the fish move into with unforeseen consequences,” researchers wrote.
The research drew on samples collected from a transect off the central Oregon Coast called the Newport Hydrographic Line, where scientists have regularly measured ocean conditions for decades.
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Image via NOAA Northwest Fisheries Wildlife Center