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Idaho Biologists say Spring/Summer Chinook Redd Count Up

by CBB Staff
Columbia Basin Bulletin - February 21, 2003

If Mother Nature helps make rivers and ocean conditions salmon-friendly, Idahoans should see good fish runs again in a few years as a result of the 2002 spawning success of chinook salmon

The spring and summer chinook last year laid more eggs in native streams last year even though fewer returning adult fish were counted at Lower Granite Dam than in 2001.

Lower Granite is the eight hydro project that the big fish pass on their way up the Columbia and Snake rivers before they reach Idaho spawning grounds and hatcheries.

Idaho Fish and Game Department biologists have been reviewing their index 2002 redd (salmon nest) counts and are seeing what they expected -- a slight increase over the number of redds counted in 2001. This may seem odd because the total number of adult spring and summer chinook counted at Lower Granite Dam in 2001 was 185,700, whereas only 97,200 adults were counted in 2002. How then to explain more redds?

The answer lies in looking at the components of the run. Most of Idaho's hatchery stocks return primarily as two-ocean (four-year-old) adults. However, many of the state's wild spring and summer chinook stocks have an equal or larger number of adults that return as three-ocean (five-year-old) adults.

Thus, for smolts that went to the ocean in 1999, those from a hatchery mostly returned in 2001, but as many or more smolts that were wild returned as adults in 2002.

The adult return in 2001 included an estimated 28,951 wild fish and 156,742 hatchery returns. The 2002 return included an estimated 37,696 wild and 59,488 hatchery fish. The 2001 4-year-old and 2002 5-year-year old spring and summer chinook's parents included only 7,263 naturally producing and 37,301 hatchery returns in 1997.

Idaho fishery biologists count the same "index" populations of spring and summer chinook in the same places each year to give them a reliable gauge of trends in Idaho's salmon. Today's index redd count program started in 1957, when all of the index populations were wild. Now, some of the populations are influenced by hatchery fish. However, many remain unaffected by hatcheries, such as in the Middle Fork of the Salmon River wilderness.

In 2002, biologists counted 3,542 redds in Salmon River drainage index areas. That compares to 3,345 redds counted in 2001, for an increase of 6 percent. Looking back at recent history shows that there has been a substantial increase in chinook spawning compared to 1997, the spawn year for the "parents" of many of the adults spawning in 2002. The 1997 redd count was 1,169.

A comparison of the 1997 redd count to the 2002 count shows a 203 percent increase, attributed to better freshwater migration conditions for smolts and a more productive ocean. Smolts from the 2002 redds will migrate to the ocean in 2004, and will return to Idaho from 2005 through 2007.

That 1997 brood migrated to the ocean in generally good river conditions in 1999, Sharon Kiefer, IDFG anadromous fish manager.

The jury's still out on the natural production of the strong 2001 spring/summer return to the Snake River system. In that year of drought they encountered low, warm flows in the tributaries at spawning time in late August and September. Those low flows also have the potential to cause density problems, Kiefer said. The best measure of success will come this spring when the young fish pass Lower Granite and estimates are made of outmigrant numbers.

"It does appear in terms of smolts per female it may be a little lower than in other years," Kiefer said of the ratio.

The spring/summer resurgence as been a boon for Idaho's anglers. Selective fisheries targeting hatchery fish were launched in 1997, 2000, 2001 and 2002 after two decades with little salmon fish.

While the overall hatchery returns were down considerably from 2001's banner run (the overall upriver spring chinook was a record since counts began in 1938), fishing was still good in Idaho in 2002.

Sport anglers caught 14,297 chinook, and released 7,455, in the South Fork Salmon averaging 11 hours of fishing per fish kept. Another relatively hot spot was the Salmon River from Hammer Creek to the Little Salmon River. Anglers caught 1,867 fish and released 406, averaging 17 hours per fish kept.

Idaho fishers caught a lot of Salmon in the Lower Clearwater, landing 5,540 and releasing 1,069. But it took 21 hours per fish. The lower Snake River yielded only 184 salmon landings, of which 79 were released, for a whopping 49 hours per fish kept.

A longer look back in time reveals that in 1962, the total redd count was 7,287 for the same group of populations that was counted in 2002. So, although the increased redd count in 2002 will help Idaho's spring and summer chinook, the 2002 redd count declined 51 percent from just 40 years ago.

What does the future hold? The 2003 adult return forecast is lower than for the 2001-2002 returns, but biologists will not know the real number until the fish show up. What we can already count on is that come late August and September, no matter what, Idaho fishery biologists will be out counting salmon redds as they have for the last 46 years.

CBB Staff
Idaho Biologists say Spring/Summer Chinook Redd Count Up
Columbia Basin Bulletin, February 21, 2003

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