Wednesday, October 8, 2014

Second Week with CPW

     September 30th:  Today the goal was to electroshock Henson Creek, a tributary to the Lake Fork of the Gunnison River.  We were going to shock a section of the creek that was about one mile upstream of Lake City.  The idea was to get a general population sample and species composition of the creek, as well as compare the numbers of stocked to wild fish.  We made the journey to the site and continued to get everything set up, once again the individual electrodes, shocking truck, holding well, live well and all the tools to process the trout.  We got everything set up and began to shock the section.  Due to the high river flow from rain the previous days, we once again got shut out.  With higher flows the electrodes voltage had to be increases.  More water makes it difficult to locate the fish, and then once they do receive a shock the high flows take them downstream very quickly. We quickly realized the flows were much to high and once again got shut down.  I have fished this creek for many years, so I was excited to see the fish it had to offer.  So we packed everything up and checked out a couple of other potential shock sites for the next season.
    October 2nd:  Today was the first day of the Kokanee Salmon spawn at the Roaring Judy Fish Hatchery.  Blue Mesa holds a landlocked/freshwater species of Kokanee Salmon.  Every fall the fish travel all the way up the Gunnison River and then take a left on the East River where they have a five mile or so journey to the hatchery.  The fish are diverted into holding ponds that are connected to fish runways.  Once the fish are in the runways, they are blocked off from downstream.   Then stations are set up to extract the eggs from the females and the milt from the males.  Some of the fish are not quite ready to spawn, so they are released back into the runways and assessed again in a few days.  Once a female is determined ready to spawn, her eggs are squeezed out into a bowl.  Then a male that is determined ready goes through the same process to extract the milt.  Eggs and milt are mixed, given some fresh water, and then sit for about a minute or so.  This minute or so allows the fertilization to occur.  Then the broken or bad eggs are removed from that individual batch, and poured into a main egg holding bucket.  On this particular day we precess upwards of 500 salmon.  About once a week, 100 salmon are taken as samples once they are spawned out.  These were taken back to Gunnion were the Otolith Bones were extracted.  To my understanding, the otolith bone is an inner ear bone in many fish species.  Once they were extracted we placed the bones in individual packets with the fish's sex, weight and length.  These are sent into a lab where the age of the fish can be determined through growth rings, as well as weight, of the otolith bones. A lot more salmon to go!      

1 comment:

  1. Interesting, I had no idea that electric shocks were used to monitor fish in rivers.