Thursday, October 25, 2012

Juvenile Pacific Lamprey in Puget Sound Streams

Pacific lamprey (Photo: R. Tabor)
Pacific lamprey
Pacific lamprey (Lampetra tridentata) are native to the Pacific Ocean and are a vital component of native fish communities. They are also used for food, medicine, and ceremonial purposes by some Pacific Northwest tribes.

Pacific lamprey are anadromous--they live in both fresh and salt water. Adults live in the ocean where they feed on the blood and bodily fluids of marine mammals and fish. After about 2 years in the ocean, they return to freshwater streams to spawn, constructing nests in small gravel where they lay their eggs. Eggs hatch after several weeks. The blind larvae--called ammocoetes--live in fine sediment on the bottom of the stream and filter-feed on algae and detritus. After 4 to 6 years as an ammocoete, Pacific lamprey metamorphose to a second juvenile life stage called macropthalmia. During this stage, the juvenile lamprey migrates out to the ocean and begins a parasitic lifestyle as an adult, growing to about 2 feet in length.

Like salmon, the abundance and range of Pacific lamprey have been reduced. To improve their distribution and abundance, the U.S. Fish and Wildlife Service (FWS) and its partners are working to address threats to Pacific lamprey, restore habitat, and fill in large data gaps. Here in the Puget Sound area, we lack basic information on lamprey, including presence and absence of these fish in our local rivers. To remedy this, the U.S. Geological Survey partnered with the FWS in 2011 to look at lamprey caught in traps designed to capture juvenile salmon.

During the spring of 2011, juvenile lamprey were captured at 18 trap sites located throughout the Puget Sound area, including Hood Canal. Pacific lamprey were identified in 13 of these 18 watersheds. Color patterns and pigmentation on their tails were used to identify ammocoetes to species. No eyed juvenile (macrophthalmia) Pacific lamprey were captured in the traps. We suspect these ocean-bound juveniles move downstream at times outside of our trapping period.

Trap locations within Puget Sound (Mike Hayes, USGS)
Trap locations within Puget Sound
One interesting find was that of "dwarf" adult lamprey. These fish measured less than 300mm in length--an adult fish is typically over 500mm long. Why so short? Do they spend less time in salt water? Or do they remain and mature entirely in fresh water? We hope to find the answers next field season!

For more information on FWS Pacific lamprey activities:

Lamprey coloring book:

Pacific lamprey fact sheet:

Follow Luna the Lamprey's return voyage from the ocean:

Visit Luna's Facebook page
Follow Luna's tweets (@LunaLamprey) on Twitter
Where's Luna now? Find her on a map


Tuesday, October 2, 2012

Coho Salmon Passage - Feeding the Quilcene River Ecosystem

Releasing adult coho salmon
above the hatchery weir
Like many hatcheries, Quilcene National Fish Hatchery (located on the Olympic Peninsula) is equipped with a weir. A weir is similar to a dam, except that a weir controls the upstream flow of fish instead of controlling the downstream flow of water. At Quilcene NFH, the weir blocks returning adult coho salmon so that the hatchery can collect the number of fish it needs to breed future salmon generations and provide fish to its affiliated tribes for subsistence. In addition to these human needs, the ecosystem upstream of the hatchery needs fish, too.

Over the last 10 to 20 years, scientists have found that naturally-spawning salmon provide a myriad of ecological benefits to aquatic and terrestrial ecosystems, including delivering nutrients as natural fertilizers and serving as "ecosystem engineers" while digging their nests in the bottom of the stream. To help meet these ecosystem needs, our office is working with Quilcene NFH to intentionally pass adult coho salmon upstream of the weir.

This year, our target is to pass a total of 800 coho salmon over the weir. September 19 marked our first passage day when we released 170 fish into the Big Quilcene River above the weir.

A tagged coho salmon to be released above the hatchery weir. 
(Note the yellow tag near the rear of the dorsal fin.)

In addition to passing fish, we are also evaluating what these fish do and where they go afterward. To accomplish this, we tag the fish prior to release and later survey the river and streams to identify where the fish spawn and how many stay upstream versus return to the hatchery. We’ll write more about these evaluations later, but for now we are happy to see salmon spawning in the Big Quilcene River and delivering much-needed nutrients to support the ecosystem that also includes federally-listed Puget Sound steelhead.