Tribes look at spawning cycles of sea cucumbers

Gonads are sampled from a sea cucumber.

Treaty tribes in western Washington are sampling sea cucumber gonads to better understand mating behaviors and figure out what’s preventing populations from thriving.

“We’re hoping to capture gonad maturity over the course of the year and potentially see spawning behavior in the water while diving,” said Viviane Barry, the Suquamish Tribe’s shellfish program manager.

Shellfish biologists are sampling up to 30 cucumbers a month March through September, looking for the progression of gonad development.

Not much is known about sea cucumbers’ reproductive cycles, except that they are broadcast spawners. Sea cucumbers generally lie flat on the bottom of the ocean floor except during spawning, when they take on a cobra pose and release gametes into the water column.

“We don’t want to open a fishery when they’re making baby cucumbers,” said Zach Vetak, a Suquamish Tribe shellfish biologist. “This is step one to find out when they’re the most vulnerable. Then we can use that to predict when the next generation will set.”

Sea cucumbers provide an important economic opportunity for tribal fishermen and were widely harvested in Puget Sound, mainly by nontribal fishermen, until the Central Sound population was depleted locally in the 1980s and 1990s, just before the Rafeedie decision. This 1994 federal decision by Judge Edward Rafeedie in U.S. v. Washington reaffirmed the tribes’ treaty rights to harvest half the shellfish from their usual and accustomed places, except those places “staked or cultivated” by citizens.

Suquamish shellfish biologists Nik Matsumoto, left, and Sarah Anderson measure the width of a sea cucumber. 

Between 1989 and 1993, the state harvested more than 3 million pounds of sea cucumbers from Dyes Inlet and Keyport areas alone, Barry said.

“Basically, out of a very small body of water, they landed a tremendous amount of sea cucumbers and the population has never really truly recovered since then,” she said.

The Rafeedie decision set a mandate for the resource to be co-managed, which means splitting the resource 50/50 between the state and tribes. Surveys in the 1990s, 2014 and 2023 showed that the population hadn’t recovered, even after quotas were significantly lowered between 1995 and 2014 and a moratorium was placed in 2014.

“We need to continue assessing the sea cucumber population and learn more about what factors are impeding them from flourishing in this area,” Barry said. “It’s a slow-growing species so we have to be really careful. There is a population down here and they’re spawning. So why aren’t they expanding? Why aren’t we seeing more?”

Squaxin Island Tribe also is taking an active role in the study. Rana Brown, a shellfish biologist with the tribe, said although the work is a big undertaking, it will help the tribe and others manage the resource to preserve it for future generations. 

The more information tribes and co-managers have about spawning by location and region, the more specifically the resource can be managed, she said. 

“It’s a conservation measure,” Brown said. “We’re trying to get more information so each area can be managed appropriately and specifically.”

Squaxin staff have been diving to collect samples every month since March in coordination with the Nisqually Tribe and Puyallup Tribe of Indians. These tribes manage the southernmost region of the resource together.

“We’ve seen a marked increase in sea cucumber abundance in our usual and accustomed areas. That’s exciting,” Brown said. “Squaxin Island members have only begun harvesting sea cucumber in recent years, which means we are invested to manage it appropriately to preserve the resource for future generations.”

Other tribes participating in the study and coordinating with state co-managers at Washington State Department of Fish and Wildlife (WDFW) include Tulalip Tribes, Lummi Nation, Port Gamble S’Klallam Tribe and Jamestown S’Klallam Tribe.

The circumference of a sea cucumber is measured during the Suquamish Tribe’s sea cucumber sampling this year. Story: Tiffany Royal and Trevor Pyle; Photos: Tiffany Royal