NOAA Fisheries researchers say new research shows that toxins from harmful algae are being found in the Alaska marine food web in high enough concentrations to be detected in whales, walruses, sea lions, seals, porpoises and sea otters.
These findings, which were reported in the online journal Harmful Algae,
www.journals.elsevier.com/harmful-algae/ document the northward expansion of the areas along the Pacific Coast where marine mammals are already known to be exposed to algal toxins. This is, however, the first documentation of algal toxins in northern ranging marine mammals from Southeast Alaska to the Arctic Ocean.
NOAA Fisheries research scientist Kathi Lefebvre led the study. She said researchers were surprised to find these toxins so widespread in Alaska, far north of where they were previously documented in marine mammals. Still Lefebvre said they do not know if the toxin concentrations found in these marine mammals were high enough to cause health impacts to these animals. Lefebvre said it is difficult to confirm the cause of death of stranded animals, but that scientists are aware that warming trends are likely to expand blooms, making it more likely that marine mammals could be affected in the future.
The Wildlife Algal-toxin Research and Response Network for the West Coast, which is funded by NOAA Fisheries, tested samples from more than 900 marine mammals that were harvested or found stranded in Alaska between 2004 and 2013. Tests showed the algal toxins, domoic acid and saxitoxin, present at low levels in some animals from each of the 13 marine mammal species examined, and from all regions of Alaska.
University of Alaska assistant professor Gay Sheffield, coauthor of the study, said clams found in the stomachs of harvested walruses and bearded seals that are themselves often eaten in coastal communities in western and northern Alaska may contain algal toxins.
Still the commonly eaten animal parts like muscle and blubber are not likely to accumulate these toxins in levels of concern for human consumption, Sheffield said.