Utah Perchology

[Therapist]

Regarding the impact of anglers on the perch population. One of the factors that impacts the population is the survival of the YOY ( young of the year). Nature realizes that many of the fry and fingerlings are going to be gobbled up, hence the huge numbers that are spawned each year. By shear numbers, it provides for the survival of the species. Where anglers impact the plan is our impact on the spawning members of the population. Using Yuba as an example. Almost ALL of the Jumbo's that were taken were gravid females. My recollection is that very seldom did we harvest a male, they were too small, under 10 inches, while all of the harvested fish were gravid females. The ratio of males to females in the population is small, you don't need that many male's to fertilize the eggs being laid. Because of this, taking a few, relatively, will not impact the spawning population. However when you start taking thousands of gravid females out of the population, you impact the number of eggs spawned, the number of fry, the number of surviving individuals. You still have the same amount of depredation, natural death, etc, the only variable is the reduced number of eggs spawned and fertilized. I don't know if anyone has ever studied that aspect of perch populations, but I know that many studies have been done on several species of forage fish in the marine environment. We are currently using that data, developed on menhaden, an over fished species in the ocean, to impact the carp population in Utah Lake. We never reached the tipping point due to harvest, however, coupled with habitat problems, low water, lack of vegetation, depredation on the eggs and fry, natural death of fry and eggs, all of these combined I believe DID reach the tipping point and resulted in the crash of the perch population in Yuba. So, over harvest prior to the spawn can have an impact on the population. Perch spawn EARLY, like under the ice sometimes. I mentioned Doug Sakaguchi ( SP) in another post. His project to provide betting spawning opportunities occurred prior to ice out.( he probably was able to do it because it was before they had to spend all their time on the put and take trout issues and SLC did not put the kibosh on it!!!!).