September 29, 2020 — The following was released by NOAA Fisheries:
For young Alaska pollock in the Gulf of Alaska, survival may depend on which way the wind blows.
A study conclusively shows for the first time that year-to-year variation in the geographic distribution of juvenile pollock in the Gulf of Alaska is driven by wind. Depending on wind direction, water movement may retain juvenile fish in favorable nursery habitats, or transport them away. Young fish that are transported to less favorable habitats are less likely to contribute to year-class strength— the abundance of adults available to the valuable Gulf of Alaska pollock fishery.
For NOAA Fisheries biologist Matt Wilson of the Alaska Fisheries Science Center, the new study addressed a longstanding question.
“When we began this research, scientists thought that lots of juvenile fish would mean a relatively strong adult year-class. But in some years our surveys found a lot of juvenile pollock, followed by a weak year class. In other years a high number of juveniles grew into a strong year class,” Wilson said. “We undertook this research to better understand why large numbers of juveniles do not always translate into a high abundance of adults.”
Wilson and co-author Ned Laman also observed that the geographic distribution of juveniles was highly variable from year to year. In some summers, a very large proportion of the juvenile population was far southwest of the main spawning grounds.
“In this study we asked: what is the cause and consequence of year-to-year geographic variability in the distribution of juvenile pollock in the Gulf of Alaska?” Wilson said.