Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Aging fish scales of Yellow Perch

Joe - You should be able to with a fair amount of accuracy determine the age of your perch using scales. As the link mentioned, collect a few scales from just behind the pectoral fin and just above the lateral line. YOu do not need to press the scale in plastic like Chris mentioned. It will help if you first clean the scale in some soapy water &/or maybe a little chlorox solution to remove any slime layer so the scale is clean. HOwever a dried scale will often curl and make it very difficult to examine, so you want to look at it damp or mount in on a glass slide under a cover slip. You should be able to use clear corn Syrup as a mounting medium. I usually soak them in a weak solution of rose bengal stain to help highlight the scale rings. You don't need real high manification for the aging process; 25X-50X maybe 100X is usually adequate (depending on size of scale). For each year the fish has lived (each winter season) you should be able to see crowding of the rings on the scale similar to the example scale shown in the link above.

COMMENTARY
I'm not sure that you really need to age your fish to solve your problem of not having larger YP. If your pond has had YP for 4 yrs and no 8"-9" perch, then there is a problem. YP with good or normal growth should be 3"-4" at age 1, 2yr = 4.5"-7", 3yr = 6"-9", 4yr = 7"-11". Even at fairly slow growth (my experience) you should have after 4 yrs YP that are 8"-9". If you in PA do not have perch this size there is a problem.

If your perch are not getting any size to them one or a combination of things could be hapenning.
1. large sized predators could be cropping or eating all or most all the perch once they reach a certain size.

2. More likely problem is the perch population in your pond is hitting a food limiting road block when they hit a certain size and not enough of the right size of food items are available for them to continue growing past a certain size. This same thing often happens with LM bass.

3. The other feature, that is closely related to No 2 or essentially the same thing, is too many perch over eating the food source and not enough food is available for them to keep growing thus stunting or very slow growth occurs beyond a certain size.

SOLUTIONS
To try and improve this problem you could try one of two things or use some sort of combination thereof.
1. Remove a fairly large number of perch thus reducing the number of "hogs feeding at the trough" as Lusk puts it. More food will then be available for remaining perch. Initially this may take a relatvely strong reduction in numbers of YP. For this to work effectively another panfish can not quickly fill the vacancy of reduced YP density. AND the natural in-pond food base has to be able to recover/reproduce fast enough to adequately feed the remaining fish/perch so growth resumes.

2. Remove some perch and enhance or add stock to increase the food chain or food availability. YP removal can in smaller ponds (less than 2ac) be mostly manual - trapping, angling, seining, although this could require a fair amount of effort depending of size of pond and numbers of overabundant YP.

3. Add an appropriate size of predator to help reduce perch numbers. Predators will also eat some of the newly stocked forage. Ideally for best control of the fishery, one should use a non-reproducing predator so they do not become too abudant and themselves become overpopulated and eventually eat all the small fish including perch. As the predator grows they will likely eat larger perch/forage which is sort of counter productive to your assumed goal of more larger perch.

4. Since I regularly raise fish in cages, I would handle the problem a little differently. I would manually remove the thin bodied or smaller, most abundant YP. Then begin a plan of annually stocking pellet fed perch. At the same time each May, I would remove (angling with worms) some 4"-6" YP, cage them and train them to eat fish food. My experience is that a fish that will bite a worm under a bobber will be an easy fish to pellet train. Pellet feed caged YP all summer, then in late fall or the next summer release them into the pond. If you can hold them overwinter, and again pellet feed them the next spring for a about month or so, a larger percentage of those caged fish will stay "on pellets". The imprinting is stonger. If you do this annually, gradually you will develop a large number of pellet eating YP and their growth will not be limited by food shortages in the pond. (For information about building small fish cages and growing fish including YP in cages see my articles in three back issues of Pond Boss magazine 2007, Mar-Apr, May-Jun, Jul-Aug).

The other option is to each year buy some larger sized pellet trained YP. If the pond has a population of pellet eating perch then a FEW non-pellet eating perch, especially the youngsters, will convert or learn to eat pellets. Your perch population with larger individuals will then gradually improve.