This is part 1 of a two-part series about the coastal cutthroat on the San Juan Islands

Mary Lou White sees hundreds of river systems in a year, but she was surprised to find coastal cutthroat living in less than two inches of water in a ditch in the Garrison Bay watershed on San Juan Island.

These fish are known for living in extreme circumstance; juvenile cutthroats can live in small pools for up to four months after a stream bed has mostly dried up. Despite their durability, White, a biologist for the Wild Fish Conservancy, fears for the cutthroat’s future.

“It’s pretty amazing,” she said.  “But this fish can only adapt to so much.”

Russel Barsh, director of Kwiaht, the Lopez-based Center for the Historical Ecology of the Salish Sea, estimates the Cascade Creek population on Orcas at 100 to 500 adult fish, the Garrison Bay watershed population at 50 to 100, and several other locations including West Beach, Bayhead, and Doe Bay with fewer than 50 fish.

This species is unique not just because of its small population, but because it is only found in the coastal watersheds between southeast Alaska and northern California.

There is little data about past cutthroat populations, but one indication of lower fish numbers is the decline of fly fishing. The cutthroat is known as a favorite among fisherman because they are an aggressive fish, guaranteed to bite most flies.

“In the 60s and 70s fly fishing was still good on the islands,” said Barsh. “If you look at historical records, the 60s and 70s was a move from agricultural to residential county that correlates to the disappearance of fresh water fishing.”

What is a cutthroat?

Some experts call cutthroat a “trouty salmon,” while others see it as a trout with salmon characteristics.

The difference between the two is that salmon are born in fresh water, then go out to sea and often return to the same stream to spawn and, soon after, die. Trout spend their whole lives in fresh water and live long after spawning.

In the San Juan Islands, some cutthroat go out to sea, while others live only in fresh water.

“Nobody knows what triggers the cutthroat out to sea,” said Jamie Glasgow, director of the Wild Fish Conservancy. “It could be the quality or quantity of the freshwater. It could be more complicated than that, we just don’t know.”

While there is some debate on its name, one thing experts can agree on is that further research on cutthroats in the San Juan Islands is needed to determine the fish’s future.

— Find out more about the conservation of this mysterious fish in part two of the series.