The Gulf waters are rich in economically valuable fish that find their way to dinner tables worldwide and generate enormous revenue for Alaska’s commercial fishing industry. These fish include halibut, herring, sablefish, pollock, rockfish, and several salmon species.
The research focuses on the presence of doliolids, a zooplankton common in Alaska’s coastal waters, and their impacts on the food chain. Throughout the marine heatwave and several times since then, Pinchuk and his collaborators used chartered vessels to collect data from the Gulf’s waters. At each collection point, they recorded water temperature and salinity, measured chlorophyll concentrations, and then used special nets to capture the zooplankton.
“We collected doliolids from different water depths…and then counted and measured them,” he explained. “The goal was to determine the density of doliolids per cubic meter of water.”
Pinchuk theorized that as water temperature increased, the doliolid population would grow as well. The problem this poses is competition for food, most notably phytoplankton and other zooplankton. The doliolids thrive on phyto- and micro-zooplankton, which are major food sources for larger zooplankton like copepods and krill, which in turn, provide food for many of the fish. Other fish species, however, eat doliolids. This means some fish might benefit from an increase in the doliolid population, while others lose out as their food sources become scarce.
Surfer was used to visualize three conditions in the Gulf of Alaska. The first showed the typical currents in the Gulf of Alaska with sampling points denoted. A second use of the software visualized the spatial distributions of important parameters – doliolids, temperature, and salinity. And the third application was to display the vertical profiles of temperature and salinity distribution at various depths in the water column.