<html>
<body>
most of the salmon and steelhead populations that I'm familiar with would
be 'best served' with some decent water. Bill<br><br>
At 02:43 PM 3/25/2011, Sari Sommarstrom wrote:<br>
<blockquote type=cite class=cite cite="">THE COLUMBIA BASIN
BULLETIN:<br>
Weekly Fish and Wildlife News<br>
<a href="http://www.cbbulletin.com/" eudora="autourl">
www.cbbulletin.com</a><br>
March 25, 2011<br>
Issue No. 568<br><br>
<font size=4>* <b>Research Indicates Wild Fish Conservation Best Served
By Minimizing Wild/Hatchery</b> <b>Interactions<br><br>
</b></font>An exhaustive look at available data for 89 populations of
chinook and coho salmon and steelhead shows that productivity in the wild
shrinks in direct proportion with increases in the percentage of hatchery
fish that join wild fish on the spawning grounds.<br><br>
“Our results suggest that the net reproductive performance of the
population will decline under all of the hatchery scenarios,” according
to “Reduced recruitment performance in natural populations of anadromous
salmonids associated with hatchery-reared fish,” a research paper
published in the March 2011 edition of the Canadian Journal of Fisheries
and Aquatic Sciences. The paper was authored by Mark Chilcote of NOAA
Fisheries and Ken Goodson and Matt Falcy of the Oregon Department of Fish
and Wildlife.<br><br>
The paper can be found at:
<a href="http://cjfas.nrc.ca/" eudora="autourl">http://cjfas.nrc.ca</a>
<br><br>
“While using hatchery fish in the short-term to reduce extinction risk
and temporarily boost depressed wild populations to re-establish
normative biological function are laudable conservation roles, such
actions come at a cost in terms of reductions in per capita recruitment
performance,” the paper says.<br><br>
“Therefore, we conclude, as did Chilcote (2003) and Nickelson (2003),
that under most circumstances the long-term conservation of wild
populations is best served by the implementation of measures that
minimize the interactions between wild and hatchery fish.<br><br>
When considering the bookends a totally wild spawning population vs. a
spawning population comprised 100 percent of fish from hatchery origins
the conclusion was stark. The hatchery populations on average produced
only 12.8 percent of the recruits (the number of fish that have matured
in the ocean as counted before they encounter fisheries) produced by the
wild population.<br><br>
“The effect of hatchery fish on reproductive performance was the same
among all three species. Further, the impact of hatchery fish from ‘wild
type’ hatchery broodstocks was no less adverse than hatchery fish from
traditional, domesticated broodstocks. <br><br>
“We also found no support for the hypothesis that a population’s
reproductive performance was affected by the length of exposure to
hatchery fish,” the paper says. “In most cases, measures that minimize
the interactions between wild and hatchery fish will be the best
long-term conservation strategy for wild populations.”<br><br>
The analysis shows that it’s wise to “keep the hatchery fish off the
spawning grounds as much as possible if the goal is to rebuild the wild
population,” said Goodson, the ODFW’s Conservation Planning
coordinator.<br><br>
“We kind of suggest that supplementation might not be the way to go,” in
many cases, Goodson said.<br><br>
“If the fish are going to wink out because there are problems” that won’t
be remedied in the shorter-term, supplementing wild populations with
hatchery fish may be necessary, Goodson said. “In some cases that is all
we can do.” But the paper advises that such decisions should be weighed
carefully.<br><br>
“Supplementing natural spawning areas with hatchery fish to benefit the
local wild population is a conservation tool that has seen widespread use
in the Pacific Northwest (ISAB 2003),” the paper says. “The intent of
this activity includes re-establishing natural production in vacant
habitats, lessening the risk of demographic extinction for wild
populations, ensuring the available habitats are seeded to full capacity,
and maintenance of genetic lineages. <br><br>
“Depending on the circumstances there is a balance between risks and
benefits that conservation managers must accurately assess and act on if
supplementation programs are to be successful and achieve their intended
effect,” the paper says. <br><br>
The analysis indicates that using wild fish as broodstock in so-called
integrated programs does not necessarily make a more wild-friendly
hatchery fish.<br><br>
“Surprisingly, we found that neither length of time exposed to hatchery
fish nor hatchery type has any effect on a population’s intrinsic
productivity,” the paper says.<br><br>
“The incorporation of wild fish into hatchery broodstocks has been
undertaken with the expectation it will ensure that the hatchery fish
produced will be genetically similar to the local wild fish. <br><br>
“Therefore, it is assumed that such genetically similar hatchery fish, if
they escape capture and spawn in the natural habitat, will not harm, and
may in fact benefit the conservation of the wild population.<br><br>
“Use of wild fish for hatchery broodstock is a cornerstone of hatchery
reforms currently being implemented for salmon and steelhead hatchery
programs across much of the Pacific Northwest (USFWS 2010),” the paper
says. “However, our findings call into question the effectiveness of this
path as a means to lessen the impact of hatchery programs on wild
populations.”<br><br>
For the analysis the researchers selected 93 populations (four later were
dropped for a variety of reasons) of anadromous salmonids from the states
of Oregon, Washington and Idaho that were known to contain both wild and
hatchery fish. <br><br>
They employed annual estimates from 1981 to 2000 of parental (spawner)
abundance for each population that were based on information sources that
differed by species and region. They then estimated the proportion of
hatchery fish in the natural spawning population.<br><br>
The next step was to estimate the “preharvest number of adult progeny
(recruits) naturally produced by each brood year of spawners using the
following four-step process,” the paper says. <br><br>
“First, we estimated annual return abundance by dividing the fishery
survival rate, calculated as 1 - fishery mortality rate, into the
observed number of wild spawners. Next, we split each return into age
categories, on the basis of the assumed proportion of different age at
maturity for each population.<br><br>
“A table of return estimates by each age category was then constructed,
and members produced by each brood year were identified,” the paper says.
“Finally, all members of each brood year were totaled to yield an
estimate of recruits.”<br><br>
“Our primary finding is that across a broad geographical range and three
different species, Ph (the percentage of hatchery fish on the spawning
ground) was a population characteristic that is negatively associated
with reproductive performance,” the paper says.<br><br>
“Intrinsic productivity declines as the fraction of the hatchery spawners
in the natural population increases.<br><br>
“We came to this conclusion after considering 12 different models that
attempted to weigh the effect of four other covariates in addition to
Ph.”<br><br>
_______________________________________________<br>
env-trinity mailing list<br>
env-trinity@velocipede.dcn.davis.ca.us<br>
<a href="http://www2.dcn.org/mailman/listinfo/env-trinity" eudora="autourl">
http://www2.dcn.org/mailman/listinfo/env-trinity</a></blockquote>
<x-sigsep><p></x-sigsep>
Kier Associates, <i>Fisheries and Watershed Professionals<br>
</i>P.O. Box 915<br>
Blue Lake, CA 95525<br>
707.668.1822 <br>
mobile: 498.7847 <br>
<a href="http://www.kierassociates.net/">http://www.kierassociates.net<br>
</a>GSA Advantage Contractor GS-10F-0124U </body>
</html>