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Columbia River smelt, sturgeon show recent increases

Lagging population estimates in past years have forced state managers to close fisheries for White sturgeon and eulachon, or smelt, one big and one small, in the lower Columbia River and tributaries. But trends most recently seem to looking up for both after years of roller coaster populations impacted by fishing and ocean and river conditions.

The “2014 Joint Staff Report Concerning Stock Status and Fisheries for Sturgeon and Smelt,” issued Tuesday by the Oregon and Washington departments of fish and wildlife charts those ups and downs, and takes a look at the future.

Based on previous Oregon and Washington fish and wildlife commission actions, effective Jan. 1, 2014, all recreational and non-Indian commercial fisheries in the Columbia River and tributaries downstream of Bonneville Dam (river mile 146) are scheduled to be closed to the retention of white sturgeon in 2014.

The only retention fisheries for white sturgeon currently planned for 2014 will be upstream of Bonneville Dam and in the Willamette River upstream of Willamette Falls.

As a result of the 2010 listing of eulachon (Columbia River smelt) under the Endangered Species Act, all eulachon-directed fisheries in the Columbia River closed as of January 2011.

For 2014, the states have been discussing with NMFS the possibility of re-establishing eulachon fisheries to gather adult catch-per-unit-effort (CPUE) data for monitoring the status of the population.

Effective May 17, 2010, the Southern Distinct Population Segment (DPS) eulachon were federally-listed as threatened under the ESA. This genetic group is composed of eulachon spawning in rivers from the Skeena River in British Columbia to the Mad River in Northern California. Of the numerous streams and rivers in this geographic area, the Columbia River has the largest spawning run.

Both species historically have shown tendencies for populations to bounce up and down in response to fishing pressure, environmental conditions in the freshwater and ocean and other factors. Signs seen recently may well point toward a rebound for populations that had been at a low ebb.

Columbia River eulachon population estimates plummeted from a high in 2001 to an all-time low in 2005 and populations remained low through the 2010 listing.

Oregon and Washington waters have been closed to the harvest of eulachon since December 2010, so no landing or CPUE information is available; however, there was anecdotal evidence (general observations by the public backed by juvenile production estimates) of adult presence improving during 2011, 2012, and 2013.

The Joint Staff Report looks at various indicators of abundance in considering smelt status. Positive abundance indicators for 2013-14 include: (1) a modest improvement in eulachon larval densities during the winter of 2011; (2) a relatively high level of Age 1+ bycatch during 2011, and a relatively high level of Age 2+ bycatch during 2012 in the Canadian ocean shrimp fisheries; and (3) favorable ocean conditions during most of the ocean-phase for BY 2009-2011 fish.

Negative abundance indices for 2013-14 include: (1) low mainstem Columbia River larval densities during the winters of 2009 and 2010; (2) decreasing adult smelt biomass tonnage in the 2010-2012 Canadian ocean shrimp fisheries; (3) warm ocean conditions during the end of 2009 and beginning of 2010; and (4) weak adult landings and CPUE for brood years 2009 and 2010.

“The mixed bag of positive and negative indicators, does not readily point toward improving or declining returns in 2014,” the joint staff report says. “However, a similar mixed forecast was made for 2013, which ended up being one of best runs in a decade, so the 2014 run is forecasted to be similar to 2011 and 2012, but could be on par with 2013.”

As of last week, smelt have been confirmed to be present in the Cowlitz and reported in the Grays rivers. Smelt return annually to the Columbia River to spawn in the mainstem and several of its tributaries downstream of Bonneville Dam. The fish typically begin to enter the Columbia River in December. Eulachon return to fresh water at age three, four, and five. Peak tributary abundance is usually in February, with variable abundance of adults through April.

Sturgeon abundance in the lower Columbia River collapsed at the end of the 19th century due to overfishing and remained depressed through the first half of the 20th century, according to the ODFW-WDFW staff report. The population began to rebound only after the adoption of management actions aimed at reducing overall harvest and protecting broodstock, particularly the 6-foot maximum size limit regulation enacted in 1950.

White sturgeon abundance subsequently increased significantly through the 1990s and supported robust recreational and commercial fisheries. Abundance of sub-adult fish began declining in the mid-2000s, prompting changes in harvest quotas and retention seasons

Joint state tagging and recovery programs were initiated in 1986 to provide data necessary to estimate the annual abundance of white sturgeon inhabiting the lower Columbia River. Abundance estimates, based on tagging conducted in one year and mark sampling extending into the following year, have been produced since 1987 with the exception of 1994 and 2004 (the estimates refer to the year of tagging, although final estimates require recoveries through the following year).

Abundance estimates for harvestable size fish (42-60 inches total length (TL) or 38-54 inches fork length) were generally low during 1988-1992 averaging 55,600 but improved significantly during 1993-1997 when average legal abundance was 169,200 fish. The estimates from 1998 through 2007 were lower (131,400 average) but more stable, ranging between 121,600-140,700 fish.

The most recent estimates declined steeply, from 131,700 fish in 2007 to a low of 65,300 fish in 2010 before increasing to 72,800 fish in 2011 and to 83,400 fish in 2012.

An alternative indicator of legal-size abundance, harvest per angler trip in recreational fisheries, remained relatively stable from 1995 through 2007, but declined 26 percent in 2008 from the previous 13-year average. The decline continued in 2009 and 2010, but at a more modest 10 percent per year, the report says.

Starting in 2011, harvest per angler trip has been increasing by 12 percent in 2011, by 4 percent in 2012, and by 39 percent in 2013.

Catch per angler trip (CPUE) of sublegal (<42 inches TL, <38 inches FL) white sturgeon decreased annually from 2004 through 2009 following eight years of mostly steady increases.

By 2008, CPUE of sublegal-size fish had dropped by almost 40 percent of the 1996-2006 average. This declining trend slowed in 2009, decreasing by just 5 percent that year, then remained relatively stable through 2012 before increasing by almost 6 percent in 2013.

Columbia Basin Bulletin

Posted on Friday, January 24, 2014 (PST) used by permission


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