Hi folks, this is Ranger Liam with another Ranger Minute for Redwood National and State
Parks and today I am standing in front of the estuary for Redwood Creek. And this is
just before Redwood Creek makes its way out to the Pacific Ocean. If I were to get into
a canoe and paddle upstream about 11 miles I would come to some of the tallest trees
on the whole planet. However what's going on behind me today is we have fish biologists
who are out here trying to determine how fish are in this creek. Let's go and check it
out! The process of counting salmon involves a few separate steps. To begin fish biologists
use a boat to cast the large seine net in the estuary. Then working as a team the net
is slowing drawn in, catching hundreds of juvenile fish. These fish will be king salmon,
steelhead, cutthroat trout, and stickleback. We are focusing on the salmon and steelhead.
Next the fish are placed in holding nets in the estuary to wait their turn to be counted.
Working in batches the fish are taken from the estuary to the counting tent where they
are first calmed by a mild sedative added to the blue basin. They are then tattooed
with blue dye and then placed in a holding bucket and given time to regain their composure.
These fish are then released back into the estuary. Why would we tattoo fish? Well we
can't count all of the fish in the estuary in one day, counting usually takes 3 days
a month 3 months a year. By tattooing these fish we can create a population estimate using
ratios. This container of chocolate covered raisins represents all of the fish in the
estuary. The yogurt covered raisins represent the fish that we have caught, counted, tattooed,
and then released back into the estuary. A month later when we recatch these tattooed
fish we can determine the ratio of marked fish to unmarked fish that we have caught
and thus estimate the number of fish in the estuary. So you see math actually does come
in handy. We should note that both the sedative and tattoo are fairly harmless and that in
the long run these population estimates will help us determine the health of the Redwood
Creek estuary as a fish rearing habitat.