NOAA Led Study Shows Walleye Pollock Resilience to Ocean Acidification
Scientists at NOAA’s Alaska Fisheries Science Center recently found that some life history parameters of walleye pollock seem to be only minimally affected by high CO2 waters. Dr. Thomas Hurst and University of Alaska colleagues Elena Fernandez and Dr. Jeremy Mathis conducted multiple experiments in conditions mimicking both present day CO2 levels in high latitude waters and those predicted to occur over the next century (280-2100µatm, pH= 7.4- 8.16). They measured the rate at which walleye pollock eggs hatched as well as their size when they hatched, along with larval survival, size, and growth rates. In elevated CO2 waters, time-to-hatch was slightly longer, but no decrease in size at hatch was measured. The researchers observed a trend toward larger body size in the higher CO2, low pH waters, but this result was not statistically significant. Because varied responses were observed among experimental trials, it is possible that egg and prey quality as well as characteristics of the foraging environment of the parental brood stock may have affected experimental outcomes.
The results of this study highlight the importance of examining other natural or human-induced factors that can affect an organism’s response to changes in pH, while also considering a species’ ability to adapt to these changes. Although the direct effects of ocean acidification on the physiological parameters of larval walleye pollock measured in this study were minimal, this critical resource species may be indirectly impacted by the responses of their food sources (i.e., krill, zooplankton, and other crustaceans) to high CO2 conditions. These impacts will likely be important factors in dictating future pollock populations, one of the largest single-species fisheries in the U.S.
This research was funded by the Pollock Conservation Cooperative Research Center, the Rasmuson Fisheries Research Center, Oregon State University’s Hatfield Marine Science Center, and NOAA's Alaska Fisheries Science Center and Ocean Acidification Program.