Thread: Crappie Biology at Kentucky and Barkley lakes

It seems with the mild winter weather, a lot of crappie anglers fishing Kentucky and Barkley lakes are having success at finding and catching crappie. Some might be asking, why the drastic change in fishing success from two years ago. The weather does play a part in it, the mild weather makes the lake accessible and pleasurable for anglers, as compared to typical cold winter weather. But, as many have heard me say, crappie populations are cyclic. Just so happens we have reach the top part, or good part, of the cycle, so to say.

Last month several anglers fishing Blood River donated the carcasses to me from the crappie they harvested. I used the carcasses to determine white from black crappie, determine sex, get a length, and removed the otoliths. Otoliths are a small bone near the brain that grow as the fish does, and rings are laid down on it, much like a tree, that can be counted to determine the age of the fish. Google if you need more information on otoliths. So, I aged 150 crappie from these anglers, 87% were white crappie. The ratio of males to females was almost a 1 to 1. When I aged the crappie 74% were age 2, 15% age 3 and 9% age 1. This is exactly what I expected on the ages. The majority were age 2, which is the 2014-year class. From our fall trap netting, we knew the 2014-year class was well above average; it’s a huge year class. The 2013 (age 3) and 2015 (age 1) year classes were above average as well. Anglers also reported having a lot of undersize crappie that they released. These are most likely representing the 2015-year class. This helps explain why crappie fishing has gotten better this year, we are at the top part of the cycle. The cycle of crappie is caused by good and bad year classes, what we also call recruitment. As compared to a few years ago when anglers complained of poorer fishing success. At that time most of the harvestable size crappie in the population came from the 2010-2012 year classes, which were below average. This would have been the bottom of the cycle. The 2012-year class was one of the worst we have documented since the mid 1980’s. One explanation for this poor year class is that in 2012 the lake never reached summer pool level due to drought conditions in the Tennessee and Cumberland river drainages. This left little shallow water “preferred” habitat for the crappie to spawn around. There are a lot of factors that are part of the spawning success equation; most are environmental, and the others are population density factors.

In regards to the population density factors, one might theorize that the more adult crappie you have the better the spawn. Wrong? Actually, most of the time in the wild, it is just the opposite. There are exceptions when it comes to species where there are very few adults, like species heading toward extinction. But for crappie that is not the case. Think about the last paragraph. The population had low adult number (2010-2012 year classes) but we had one of the better spawns (2014) than we have seen in a long while. Populations with low adult densities typically produce larger year classes. Low adult density populations will likely spawn earlier than populations with high densities of adult fish. Early spawning may lead to decreased competition and longer growing seasons than spawning late, which allows for increased growth, larger size, avoidance of predation, and better overwinter survival of offspring.

During these years when harvest was down, due to the poor year classes, I heard from a lot of disgruntle anglers that “we” needed a 11 or 12-inch size limit on our lakes (KY and Barkley) like they have down in Mississippi (Sardis, Grenada, Washington) on their good crappie lakes. Anglers argued that if we protected the crappie more, it would allow the crappie to spawn a few more years before being susceptible to harvest. This might help flatten out the cycle mentioned above. (though refer to the previous paragraphs on density dependent population growth and environmental factor that affect recruitment). Additionally, if we had a larger size limit, we could have more 2 to 3-pound crappie like they have in the Mississippi lakes. Believe it or not, I do stay in contact with biologists from other states and we do share data. So I have reviewed crappie data from Mississippi to compare to our lakes. If I thought we could change our regulations to achieve what they have, we would.

One explanation for the bigger crappie in Mississippi, is their growing season. It is longer in the south. Again, I have reviewed their data, but I recently had a friend (Mr. Scott Waldrop), who fishes down in Mississippi, to bring me back some carcasses of crappie he caught down there. Scott was recently at Lake Washington crappie fishing, and he brought me back 15 white crappie carcasses. He had caught 75% females and 25% males. But the interesting thing is, 86% were age 2, the 2014-year class. Though, there was a difference. The average length for these age 2 crappie from Mississippi was 12.0 inches. Going back to the age 2 crappie from Blood River, their average length was 10.2 inches. So, the proof is in the catch, Mississippi crappie are faster growing. Additionally, I made the comparison of a 12.8-inch crappie caught from Lake Washington, which was age 2, to a KY Lake crappie that was 12.7 inches, though its age is 5. (I have added a picture of the otoliths for you to see, MS on left, KY on right). Hence, this is why we don’t have a larger size limit on our lakes. Our crappie don’t have fast enough growth. Crappie are a relatively short lived fish. We rarely see a crappie over 7 years old in our lakes. With our crappie’s slower growth, if we had a 12-inch size limit, most would be in their last few years of life. This would leave a reduce chance of every being harvested (fishing mortality) before potentially dying of old age (natural mortality).

We have also recently re-examined the need for pole limits. Using the past decade of creel data from Kentucky Lake and Lake Barkley surveys, it is evident that the number of anglers utilizing 3 or more poles has increased. At Kentucky Lake the percentage of crappie anglers using 3 or more poles has increased from 17% to 64% in the past decade. We can estimate from this data, if 100% of the crappie anglers would have used 3 poles at KY Lake, crappie harvest might have increased to almost 147,000. This is a 15% increase to the actual harvest of 128,000 reported during the 2015 creel survey. If all anglers would have used > 5 poles, it is estimated that harvest would have increase by 36%. If all crappie anglers began using >5 poles, this would be the worst case scenario where all crappie anglers use the most efficient method. In this scenario, harvest might increase to an undesirable level. In addition, using the creel data, we can also estimate how a pole limit might affect the harvest of crappie. By implementing a 3 pole limit we estimated harvest would only be reduce slightly. The average reduction to harvest at both lakes is about 5%. Though, if overharvest was to become a concern, we feel pole limits might be better accepted by crappie anglers than a further reduction in creel limit from 20 down to 15 or even 10.

Thank you. Very interesting read.