Monitoring Our Endangered Coho Salmon
So an adult coho is about 60-75 cm in length which is, I don’t know, about like that
big, and they’re bright red on the sides and the males have a really hooked snout kind
of like that whereas the females are, you know, normal fish mouths and they swim into
the creeks in the winter and spawn. The female lays the eggs, the eggs hatch into fry, and
then they grow into juveniles, and then they grow into smolts which swim out of the rivers
and into the oceans and they live in the ocean for about two years and they come back as
adults and spawn, and it keeps going and going, so it’s like a three year lifecycle. [Mike Reichmuth]
We are currently monitoring coho really to
get the status and trend of the species. They usually spawn up in the headwaters of
the stream and then continue to use the rest of the stream during their life all the way
until they get to the estuary and out to the ocean, so by monitoring them over their entire
lifecycle we’re able to really get the health of the entire ecosystem of the stream. Currently we have three main creeks that we
monitor. We monitor Redwood creek in the South.
We also monitor Pine Gulch Creek which is in the Bolinas area, and then the most northern
creek that we monitor is Olema Creek. These three creeks are some of the most southern
populations, especially if you look along the Pacific Coast, only Santa Cruz is South
of us. In general we have our monitoring encompasses
three main life stages. One is we monitor the adults when they come back
to spawn. When we monitor our adults, their ability really to overcome obstacles and get to their spawning
habitat is pretty amazing. In the springtime we monitor the smolt life
stage. This is the time when the fish are going out to the ocean. [Ben Atencio]When you get to the site we have the fyke
net which leads into the pipe which leads into the box and we check the box to see if
there’s any fish, clear out all the debris and all the fish and then count the fish.
We measure ‘em to millimeters and weigh them to the hundredth of a gram, and so yeah,
we just go from trap to trap counting fish. It kind of seems like for the smolts at least
every fish kind of has its own personality. Some fish will be really squirmy and really
fighty and then other fish will just be really relaxed and you can handle them just fine. [Mike Reichmuth] And then we monitor the fish when they’re – in the summertime – when
they’re considered juveniles rearing in the creek and during this life stage this
gives us an idea of what their success was in terms of their ability to survive the spring
and also feed and grow. Currently our monitoring is showing that the
population is decreasing. In the last few years we’ve noticed a large decline. Even
before that decline they were only at about 5% of what their historic levels were. So
really what we’re trying to do is figure out why is it decreasing and then figure out
how do we save these fish from no longer being in these creeks.
In terms of the past threats to coho is we have activities such as damming, infrastructure
such as buildings, roads, water withdrawals, fishing, and agriculture are some of the main
threats we’ve had in the past. Currently, we still have some of those.
Hopefully through some of the park’s most recent efforts of restoring some of the key
areas of the creek that the coho – that we know the coho will utilize – we’ll
be able to increase the population and restore these populations back to their historic levels.