|Biologists from the Oregon Department of Fish and Wildlife pull in a seine net at the mouth of the Alsea River while monitoring juvenile chinook salmon in coastal estuaries.
-Photo by ODFW-
NEWPORT, Ore. – What does the future hold for chinook salmon populations in streams along the Oregon coast?
That is what biologists from the Oregon Department of Fish and Wildlife hope to find out with data collected from a research project that will take place this summer on eight coastal rivers.
Over the next three months ODFW biologists will use seine nets to collect juvenile salmon in the tidal zones of the Nehalem, Tillamook, Nestucca, Salmon, Siletz, Yaquina, Alsea and Siuslaw rivers to see whether they can find clues to future coastal chinook salmon returns.
Biologists are delving into this research because they are concerned about the recent downward trend in coastal fall chinook populations. This year the expected number of adult chinook returning to coastal rivers was low enough that in June the Oregon Fish and Wildlife Commission ordered substantial reductions of coastal fall chinook sport fisheries, including the complete closure of the Nehalem River.
“We believe this monitoring will give us a sense of whether we should expect low adult returns farther down the line or if juvenile numbers are relatively stable, meaning run size could rebound with improved ocean conditions,” said Derek Wilson, assistant district fish biologist for ODFW’s mid coast district.
Chinook salmon that emerge from gravel beds in the rivers during the late winter and early spring typically swim downstream and spend the summer in the tidal zones or “estuaries,” where they grow and prepare for their migration to the ocean. Researchers want to monitor the relationship between adult and juvenile chinook. Specifically, they want to find out how the abundance of juveniles relates to the abundance of spawning adults. Smaller numbers of fish may reduce competition for habitat to the extent that the effectiveness of the adults and the survival of the juveniles actually improves. This can help to buffer the population from extremely low levels, potentially resulting in more rapid recovery.
“With more information we may have more options in the way we manage these fish and may not have to take such severe actions in the future,” said Wilson.
Seining at the mouths of the eight rivers began in early July and will continue through September at periods of low tide. While the research is aimed primarily at juvenile chinook salmon, biologists will also document the occurance of other species they observe, including juvenile greenling, lingcod, smelt, herring, anchovies, and several varieties of perch. All of the fish will be handled in the water near shore and will then be released unharmed.