NOAA National Marine Fisheries Service conservationists are looking into why Hawaiian Monk seal numbers continue to decline despite their best efforts and asked NOS scientists to test for evidence of what might be ailing the animals. Using state-of-the-art analytical methods, the researchers discovered that nearly 20 percent of the samples taken from free-ranging monk seals had ciguatoxin levels in their blood high enough to cause symptoms in laboratory animals.

Ciguatoxin comes from certain tiny algae that live in reefs and are eaten by small fish. Larger fish prey on the little ones, and so on, concentrating toxins up the food chain. Toxicity symptoms in seals may be analogous to chronic fatigue syndrome in humans, making it difficult to tell how seriously the seals are affected.

Sick seals struggle to catch enough prey to survive, leading ultimately to declining populations. NOAA Fisheries wants this information to adjust management plans for this critically endangered mammal.