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<font face="Garamond" size=4>Sari <br><br>
You will remember J.O Snyder's Klamath River salmon production findings
of nearly a century ago
<a href="http://www.krisweb.com/biblio/klamath_cdfg_snyder_1931.pdf" eudora="autourl">
http://www.krisweb.com/biblio/klamath_cdfg_snyder_1931.pdf</a> that there
appeared to be several chinook salmon life history strategies (or a
'diverse portfolio' as suggested by one of the commenters in the article
you've kindly shared with the list) at play in the Klamath basin back
then<br><br>
Those, such as Frank Fisher and Marty Kjelson, who delved deeply into the
history of chinook salmon life histories in the Central Valley note that
far-and-away the majority - like 95 percent - of the system's young
salmon arrived in the then-expansive Bay-Delta estuary on late-winter
freshets and historically reared there successfully<br><br>
All that, of course, has changed - on the Klamath, in the Sacramento-San
Joaquin Bay-Delta estuary ecosystem and, alas, in the lower Columbia
River system, which, like that of the Sacramento-San Joaquin has been
diked, drained and basically degraded as juvenile salmon rearing
habitat<br><br>
The salmon have always had the ways. The question is whether we have the
will.<br><br>
'Best,<br><br>
Bill<br>
</font>At 03:15 PM 5/20/2011, Sari Sommarstrom wrote:<br>
<blockquote type=cite class=cite cite="">THE COLUMBIA BASIN
BULLETIN:<br>
Weekly Fish and Wildlife News
<a href="http://www.cbbulletin.com/" eudora="autourl">
www.cbbulletin.com</a><br>
May 20, 2011 -- Issue No. 576<br><br>
<b>* Salmon History: Centuries Ago Juveniles Entered Columbia Estuary
Younger, Smaller Than Today’s Fish<br><br>
</b>Chinook salmon reared in the upper stretches of the Columbia River
watershed 250 to 500 years ago used to leave their freshwater habitat and
enter the estuary and possibly even the Pacific Ocean when they were
smaller and younger than most of their contemporary
counterparts.<br><br>
Researchers tracking the life history of salmon long before dams were
built on the Columbia say the finding suggests that fisheries leaders may
need to manage for a diversity of life histories.<br>
<br>
Results of the research have been published in the Canadian Journal of
Fisheries.<br><br>
“The Columbia River estuary is an amazingly productive system and there
clearly are advantages for fish to enter into that environment,” said
Jessica Miller, an Oregon State University ecologist and lead author on
the study. “Yet today fish remain in fresh water for a longer period of
time possibly because they must navigate past the dams, and because
river flows during their ocean migration have been reduced with the
development of the hydropower system.<br><br>
“Chinook salmon have a more diverse portfolio than other salmon species,
which may be one reason some of their populations are doing so well,”
Miller added. “Managing the resource to retain that diversity seems like
a logical strategy.”<br><br>
“We know there are advantages for the salmon to reach a certain size
before entering the ocean, especially in avoiding prey,” Miller noted.
“But there may be long-term advantages to having individuals that migrate
at a diversity of sizes.”<br><br>
To learn more about ancient salmon runs, the researchers worked with the
Confederated Tribes of the Colville in Washington, where they obtained
the skeletal remains of salmon from a former archaeological site just
downriver from Grand Coulee Dam. The fish, which the scientists dated to
250-500 years ago, were in an area of the Columbia River which is no
longer accessible to migrating fish because of the dams.<br><br>
One goal of the research was to see if fish that used to go upstream of
Chief Joseph Dam the farthest upriver that salmon and steelhead return
had different characteristics than present-day fish. To do this, they
looked at the bony structure within the salmon’s ears called an
“otolith,” which accretes calcium carbonate and forms growth rings. By
examining the growth rings and isotopes within otoliths, scientists can
ascertain the age of a fish, where it lived and sometimes what it has
eaten.<br><br>
“It’s pretty amazing that we can look at the otolith of a 500-year-old
fish and determine which river it likely originated in and at what size
it entered marine waters,” said Miller, an assistant professor of
fisheries and wildlife who works out of OSU’s Hatfield Marine Science
Center in Newport.<br><br>
They do this by analyzing the ratio of strontium-to-calcium isotopes in
the otolith. A high ratio indicates a fish has been living in salt water,
while a lower ratio suggests recent freshwater history. They also can
examine two isotopes of strontium, which can provide information on the
river of origin.<br><br>
“We can also estimate where in the river system they were, because as you
move east to west, the rocks get younger and the strontium values
change,” Miller said. “In most cases, the isotopic signature is
extraordinarily revealing.”<br><br>
Miller also was lead author on another study, published in the Marine
Ecology Progress Series, which examined diversity of fish runs in modern
populations. Focusing on Central Valley (California) chinook salmon, the
study determined that adult fish typically had begun their juvenile
migration in two “pulses.”<br><br>
A majority of adults had begun their seaward migration as larger
juveniles (75 millimeters or longer), which typically leave rivers in
mid-April to May. But the adult sample also contained fish that had begun
their emigration as smaller fish (less than 55 mm). Though fewer in
numbers, these smaller fish were still significant and typically left
rivers in February and March.<br><br>
“In the Central Valley, the vast majority of hatchery production is
focused on larger juveniles, whereas most of the naturally produced fish
appear to emigrate at a smaller size,” Miller said. “Similar to the
variation in adult run timing which may protect runs against
catastrophic floods, drought or disease variation in the timing of
juvenile migration to the ocean may be important for long-term
survival.”<br><br>
Other researchers on the Canadian Journal of Fisheries study include
Virginia Butler, Portland State University; Charles Simenstad, University
of Washington; David Backus, Williams College; and Adam Kent,
OSU.<br><br>
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