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Hatchery Methods Developed For Pacific Lamprey With Hopes Of Supplementing Slumping Populations
Posted on Friday, September 14, 2012 (PST)

New programs to develop methods for the hatchery culture of Pacific lamprey are under way in on either side of the Cascade Mountains in Washington with the goal of creating a tool for restoring depleted stocks of a fish of great cultural and environmental importance in the Columbia River basin.

Research begun this year at the Mukilteo Research Station on Seattle’s northside led by Mary Moser of NOAA Fisheries’ Northwest Fisheries Science Center. The station is an arm of the NWFSC.

In central Washington, Yakama Nation biologists are conducting similar experiments to evaluate lamprey needs and behaviors in the very earliest stages of their life cycle.

Moser is working on the project with the Confederated Tribes of the Umatilla Indian Reservation. She and other researchers there have been conducting experiments to explore culture methods for the imperiled species.

An initial batch of lamprey eggs was housed in a re-circulating freshwater system research station. The developing eggs have been tested with various egg disinfection methods and monitored for viability.

Experiments will continue at Mukilteo to assess methods for culture of Pacific lamprey larvae, known as ammocoetes. These larvae burrow in sediments and filter feed during their extended freshwater residence, presenting many challenges, and opportunities, for fish culturists.

In this first year of research Moser’s project has employed a makeshift system of 30 tanks, each with a capacity of 30 liters. The tanks are outfitted with a variety of gravels and also fine sediments. The eggs are deposited in the gravels or cobble, the type of substrate that lamprey prefer for spawning.

Mating pairs of lamprey construct a nest by digging together using rapid vibrations of their tails and by moving stones using their suction mouths. The young hatch in just a few weeks and, after a pause of about five days, swim or drift downstream.

“The do shift downstream to where the sediment is finer,” Moser said. They would appear to seek backwater or eddy areas of low stream velocity where sediments are soft and rich in dead plant materials

“Then they reside there for what’s thought to be 5-7 years” as ammocoetes before, ultimately, heading for the ocean, Moser said.

The larva burrow into the muddy bottom where they filter the mud and water, eating microscopic plants (mostly diatoms) and animals.

Before leaving, the lamprey experience a metamorphosis into the juvenile phase (macropthalmia), developing eyes, a mouth for feeding and a gut (a changed digestive system that will be capable of processing a new diet in saltwater). In the ocean the lamprey parasitize other fish to sustain themselves, feeding on blood and tissue.

Like salmon, Pacific lamprey are anadromous, spending two or three years in the ocean before returning to freshwater to spawn. Pacific lamprey are susceptible to many of the same threats facing other anadromous species listed under the Endangered Species Act—reduced access to spawning habitat, degradation of spawning and rearing areas, predation, and impassable sections of the Columbia River hydropower system.

Their long residence time in freshwater also makes lamprey highly vulnerable to the effects of pollution.

Declining lamprey populations in the Columbia River basin have spurred the development of specialized, lamprey-friendly, passage ladders at hydro projects where the eel-like fish have historically had passage survival of only about 50 percent. The new “lamprey passage” devices are designed to take advantage of the species’ unique climbing ability.

Before its decline, the lamprey was a very important fish for many of the tribal people of the Pacific coast and interior Columbia River basin. Tribal people harvested these fish for subsistence, ceremonial, and medicinal purposes. The spawning Pacific lamprey also import marine-derived nutrients that help sustain freshwater ecosystems.

“That base is gone. The lamprey missing link is important,” Moser said of populations that are just a fraction of what they were 20-30-40 years ago.

A number of factors – including hydro system passage and habitat degradation – are believed responsible for a sweeping decline in the population of Pacific lamprey returning to the Columbia River basin.

“They have been trending downward since the ‘40s and ’50s,” said Brian McIlraith, Pacific lamprey project leader for the Columbia River Inter-Tribal Fish Commission, which provide research services and technical advice to the Nez Perce, Umatilla, Warm Springs and Yakama tribes.

“2010 was probably the lowest year ever” with only about 10,000 lamprey counted passing over Bonneville Dam via salmon ladders, those special lamprey devices and other means, McIlraith said. “They’ve come up (lamprey counts at Bonneville during the past two years) but they’re still well below counts from 10 years ago” and even farther below counts from decades past.

“Counts are reduced radically after you get above McNary Dam,” said Bob Rose, the Yakama Nation’s hydro program coordinator. McNary is the fourth dam on the Columbia River that the fish must pass on their way to Yakama country. Bonneville is the first.

“The population is pretty much done here,” Rose said of the sparse presence of lamprey now above McNary in the Snake and the mid-Columbia. There have been zero lamprey counts in recent years at Roza Dam on the Yakima River, he said. The Yakima flows into the Columbia above McNary and the big river’s confluence with the Snake.

The problem is being attacked on a variety of fronts, such as the “translocation” of adult fish by tribes from places of plenty, in a relative sense, to rivers upstream. The work being done this year at Mukilteo is intended to increase knowledge of young lamprey needs, and to develop protocols for producing them in hatcheries.

Learning to hatch out lamprey and keep them healthy in the early stages is seen “as possibly a critical supplementation tool” at some point in the future, Rose said. Supplementation is the practice of outplanting hatchery produced fish in rivers with the hope some number of them will complete their life cycle by spawning in the wild.

So far so good for the Yakama experiment.

The Yakama biologists have rigged up “a couple of very modest facilities” at two existing hatcheries, Marion Drain Sturgeon Hatchery near Toppenish, Wash., and at tribe’s hatchery in Prosser, Wash.

“We’ve got tens of thousands growing and feeding,” Rose said. The plan is to continue monitoring their growth and habits.

“We’re not going to release any of these little guys this year,” Rose said.

With lamprey juveniles and adults in low numbers and hard to find in upriver habitat, the Yakama biologists have been mining downstream sites for adult broodstock -- fish captured at John Day and The Dalles dams, as well as lamprey that had been housed at Oregon State University.

The tribes have dabbled in the past in lamprey propagation but “this year we did it really intensively,” Ralph Lampman, who heads up the lamprey research project.

Genetic samples are taken from the bloodstock so that their progeny can be identified down the road.

The tribe has experimented with various incubation techniques, including those developed in Japan and Finland. Those two countries are as advanced as any in the art of artificial production of lamprey.

The two studies ongoing this summer are believed to be the first concerted effort to develop lamprey incubating and rearing techniques in the Columbia River basin.

Like Moser’s project, the Yakama research this year at assessing such things as preferred food types, potential optimal rearing densities, favorable incubation flows and temperatures and other factors. They also chart survival and growth rates.

The Yakama experiment will also attempt to ascertain how long the lamprey should be fostered in the hatchery.

“We need to find out what’s the best time to release” the lamprey, Lampman said.

Because young lamprey are fewer and even harder to find upriver, some of the hatchery fish will also be used for research purposes to solve other mysteries about the fish’s early life.

There’s still a lot to learn about the little studied, at least when compared to salmon, lamprey.

“They’re such a different fish,” Rose said.

To this point in the process the young Yakama hatchery lamprey are “still alive and growing – nothing but success here,” Rose said.

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