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Coho pre-spawn mortality movies
Ecotoxicology and Environmental Fish Health
Coho Pre-spawn Mortality in Urban Streams
These videos were taken during an intensive field study in the fall
of 2002. The first video shows the normal behavior of adult coho in
a small, non-urban stream (a tributary to the North Fork of the
Stillaguamish River, WA). The remaining three videos show coho from
Longfellow Creek, an urban stream in Seattle. The fish in these
videos are "symptomatic" - that is, they show behavioral symptoms that
are indicative of an underlying neurological or respiratory disorder.
The videos show the progression of the disorder, from a loss of
orientation to a loss of equilibrium. Affected fish die within a few
hours of exhibiting symptoms. Research scientists in the Ecotoxicology
and Environmental Fish Health Program are actively investigating the
problem of coho pre-spawn mortality in urban streams of the Puget
Sound Basin. For more information about this research, please send email to Dr. Tracy Collier.
Download the
QuickTime
plug-in to view the movies.
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Movie 1 - Coho in a non-urban (reference) stream. These animals have been in
freshwater for several days or weeks, and they have transitioned from a
silver coloration to the reddish colors of adult spawners. Their tails
show abrasions from digging nests (redds) in the gravel bottom of this
shallow stream. They are oriented to the flow of the stream, and they
exhibit social interactions with nearby animals.
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Movie 2 - A symptomatic fish in Longfellow Creek, West Seattle. This animal
is in the early stages of a disorder that will eventually lead to the
animal's death. At this point, the fish has lost orientation, and is
swimming in circles near the surface of the stream. The fish is no
longer oriented to flow, and it tumbles over a log and drifts downstream.
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Movie 3 - A different fish at a more advanced stage of the disorder. This animal
has lost equilibrium, and is drifting downstream. The affected fish is gaping
and has stopped swimming. It periodically attempts to regain equilibrium
(without success). The silvery color of this animal is an indication of recent
entry into Longfellow Creek.
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Movie 4 - Affected fish ultimately stop swimming altogether. This animal is
lying on the bottom of the stream and gaping. Note the extended or splayed
position of the fins. This was commonly observed in coho that died in
Longfellow Creek in 2002.
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EC Home | Ecotoxicology
last modified
02/16/2007
Web site owner: Northwest Fisheries Science Center
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