A new NOAA Fisheries study concludes that which way the wind blows is a critical factor in the survival rate of young Alaska Pollock in the Gulf of Alaska.
NOAA Fisheries biologist Matt Wilson of the Alaska Fisheries Science Center says the study addresses a longstanding question regarding the impact of wind on the survival rate of juvenile Pollock in the Gulf. Research biologists found that depending on wind direction, water movement may keep juvenile fish in favorable nursey habitat or move them out.
Fisheries scientists thought at the start of the study that an abundance of juvenile fish would produce a relatively strong adult year-class. Yet some years this did not transpire, so researchers took another look, and it turned out that wind is the culprit.
Wilson said that the consequence of a large proportion of the juvenile population being transported to the southwest is that many of those fish are likely lost from the Gulf. The study provides new insight into the importance of wind to Pollock population dynamics. “The findings argue for including wind-driven surface transport along with other important factors like temperature, prey, and predation that have been used in stock forecast models,” Wilson said.
In their first year of life Pollock are weak swimmers who drift where currents take them. Where they end up influences whether they will contribute to the adult Gulf of Alaska population.
Wind is the primary driver of water low in the western coastal Gulf of Alaska. Researchers found that when downwelling-favorable winds prevailed during and after spawning that juveniles appeared to be retained in upstream habitat near the main spawning area around Kodiak Island. NOAA Fisheries scientists are also looking at the contribution of diet to the dramatic reduction of the 2013-year-class of juvenile Pollock in the western Gulf.