THE recent Washington Department of Fish and Wildlife decision to close steelhead fishing on all rivers feeding Lake Washington and Lake Sammamish is a dramatic move to compensate for the continuing predation of returning steelhead by sea lions at the Ballard Locks.
Bear Creek, which feeds the Sammamish River between Lake Sammamish and Lake Washington, had 334 steelhead return to spawn in 1986. In 1993, not a single spawning steelhead was observed by Fish and Wildlife biologists in Bear Creek. In fact, the wild winter steelhead run in Lake Washington tributaries has diminished nearly 80 percent in the past 10 years and, according to state fisheries biologist Bob Pfeifer, nearly two-thirds of this decline is from sea lions eating steelhead at the Ballard Locks.
Herschel was the first California sea lion spotted preying on steelhead at the Ballard Locks in the late 1970s. Herschel has since been accompanied and/or replaced by numerous other California sea lions that frequent the Locks because they can catch fish by corralling them against the cement walls. The steelhead returning to spawn are vulnerable at the Locks because they must rest for several days while their bodies undergo the metabolic changes necessary to adapt from their saltwater ocean habitat to the freshwater lakes and rivers.
Because the California sea lion is protected under the Marine Mammal Protection Act, Fish and Wildlife personnel have been legally prevented until now from using lethal measures to remove sea lions from the Ballard Locks. Since 1985, state biologists have attempted some creative, yet ineffective, tactics to solve the problem, but the sea lions have foiled these plans:
-- Sea lions were offered tainted fish to make them sick, but quickly learned to avoid dead food.
-- Sea lions were bombarded with underwater recordings of orca whale calls but soon seemed to catch on to the bluff.
-- Sea lions were shot at with rubber-tipped arrows and subjected to exploding underwater firecrackers, but this probably disturbed the steelhead more than the sea lions.
-- Sea lions were trapped and shipped back to both the Oregon and California coasts on multiple occasions, but each time the animals swam back to the Locks in a matter of weeks.
The predator-prey fishbowl situation at the Ballard Locks is an environmental dilemma that has stubbornly resisted resolution and has pitted special-interest groups against government agencies. William Rogers, University of Washington professor of law, observes: "The sea lion situation at the Locks has evolved into a dysfunctional environmental problem where meaningful solutions are being replaced by guns and law suits."
Threat of lawsuit against the Marine Mammal Protection Act by the steelhead conservation group Trout Unlimited pushed Congress to write a nuisance clause into the Marine Mammal Protection Act, signed into law by President Clinton last May. The nuisance clause, which specifically mentions the problem sea lions at the Ballard Locks, allows authorities to kill individual problem animals of a listed species where all other means have failed.
Last month, Fish and Wildlife proceeded under the nuisance clause and formally requested federal permission to lethally remove sea lions at the Locks. However, biologist Pfeifer notes that animal-rights advocacy groups such as Greenpeace and People for Puget Sound have hinted they will file a counter-suit if Fish and Wildlife personnel kill any sea lions. Due to the potential of additional lawsuits and because of the time-consuming environmental impact statement process necessary to get federal authority to act under the nuisance clause, Fish and Wildlife personnel are testing an underwater high-frequency sonar they hope will scare sea lions. It appears the state is hedging its bets with the sonar deterrent due to the chances that the lethal-removal option might become a legal standoff. But will the high-frequency sonar deterrent succeed where all other deterrents have failed?
When approaching environmental conflicts occurring in a system altered by man, it is useful to compare a natural system such as an undisturbed coastal estuary - located where fresh water carried by a river empties into and mixes with the ocean - with a highly developed and urbanized estuary like the Ballard Locks. (The area where the Locks are located was originally a natural estuary where Lake Union flowed by natural stream into Shilshole Bay.) Migrating steelhead are killed by sea lions in substantially fewer numbers in natural estuaries than is occurring at the Locks because natural estuaries provide cover, such as large rocks, undercut banks, submerged trees, root wads and aquatic plants where steelhead can escape from predators. Conversely, the Ballard Locks consists of straight, dead-ending concrete walls.
One solution to the stalemate at the Locks may be to provide migrating steelhead with artificial cover such as underwater "islands" of tightly spaced 6- to 8-feet-high vertical rods installed into the channel bottom. If these underwater "islands" were built into the channel bottom immediately below the fish ladder, steelhead would be provided with an escape matrix of vertical steel or concrete rods where they could swim but sea lions could not follow. With this protection, steelhead could adjust to the fresh water and safely migrate up the fish ladder.
Lower steelhead mortalities from predators in natural estuaries suggest that if cover is available, steelhead will use it. Furthermore, locating an escape matrix below the fish ladder may be ideal because Fish and Wildlife studies at the Locks show that steelhead are drawn to the freshwater "attraction flows" coming out of the fish ladder.
According to Pfeifer, state decision-makers have not pursued such an option because of: 1) the perceived construction costs and because state fiscal planners have not earmarked funds for this project; 2) concerns on the part of the Army Corps of Engineers, the agency responsible for constructing and operating the Locks, that an underwater structure may be damaged by hydraulic scour produced by the flushing action of the Locks; and 3) concerns on the part of the Army Corps of Engineers that an underwater structure might interfere with boat traffic.
However, these concerns may be solved by placing the underwater escape matrix on the south side of the Shilshole Bay channel immediately below the fish ladder. Hydraulic scour is substantially lower on the south side of the channel because the southernmost spill gate is only open for short periods during early spring. Furthermore, boat traffic is currently prohibited in this area.
One-time construction costs and minimal maintenance costs of an artificial escape matrix would certainly be cost-competitive with the expensive yet unsuccessful deterrents attempted thus far to save the steelhead run. Jerry Pavletich, West Coast representative for Trout Unlimited, estimates that nearly $1 million in public funds have been spent so far by agencies to solve the sea lion problem at the Locks. The potentially permanent solution of an escape matrix certainly seems more productive than fighting legal battles with special-interest groups and lobbying for additional allowances. Because the Ballard Locks is a federal project, perhaps installation costs could be a joint federal-state venture.
If saving the wild steelhead in King County is a priority, the cost we can least afford is time. According to Frank Urabeck, vice president of Western Washington Trout Unlimited, only 70 steelhead were counted at the Locks last year and a smaller return is expected this winter. While we search for answers acceptable to all interest groups, the steelhead are disappearing in front of our eyes.
Tom Blood is an environmental scientist with a Seattle firm and worked a summer at the Ballard Locks. He has written articles on natural resource management issues.