Washington Sea Grant-funded researchers investigated how domoic acid and saxitoxin, which are produced during harmful algal blooms (HABs), spread through the food web. They focused on species that are commercially and culturally important to the Makah Tribe, including several types of fish and gray whales. The scientists worked with local fishermen to obtain stomach and muscle samples from fish and surveyed samples of gray whale scat and prey. They then ran enzyme-linked immunosorbent assay (ELISA) analysis on the stomach samples in order to determine if the samples contained algal toxin concentrations above the threshold for human consumption.
The Makah’s usual and accustomed fishing grounds are located in the California Current, a highly productive feeding area for marine mammals, seabirds and fish. This area is also subject to harmful algal blooms (HABs) that produce toxins such as domoic acid and saxitoxin. These toxins can accumulate throughout the food web, from zooplankton to mammals, and can cause illness in marine animals as well as the people who eat them.
Results Thus Far
In order to detect domoic acid and saxitoxin concentrations, the scientists ran enzyme-linked immunosorbent assay (ELISA) analysis on 42 of the fish stomach samples. Concentrations ranged from below detection to 407 ng toxin/ g stomach contents for domoic acid and 386 ng/g for saxitoxin. Both of these upper values fall well below the regulatory limit for human consumption. It was a “low feeding” year for the gray whales: the researchers saw few whale sightings and very little evidence of the whales’ zooplankton prey, and so they were able to collect fewer scat samples than anticipated.