TPWD just finished trap netting for crappie at Sam Rayburn to try and find some measure of crappie abundance for the lake (I emphasize the word try here). Before I go any further I’ll explain what a trap net is and why they are usually a poor sampling tool for crappie, even though they are our current weapon of choice. A trap net consists of four 2.5’ diameter hoops that are connected to two 3’x 6’ frames with a 60’ leader. TPWD has used trap nets for years to gauge crappie populations throughout the state. The things we are looking for when we deploy these nets are how many crappie we catch in each of these nets per night and the size structure of the fish and how this compares to previous years. TPWD protocol dictates we are to set these trap nets perpendicular off the bank. Now I know what you crappie fishermen are sitting there thinking, that crappie are further from the bank than that 60’ leader and we probably won’t catch very many fish, and you are correct. Recently, TPWD allowed its district biologists to determine whether or not trap nets are used as an index tool for crappie populations at lakes they are responsible for. This was done because the catch rates from most trap nets are so low that it is impossible to come to any conclusion as to what it means. A good trap net haul in most lakes around here will be at best 10 fish with most hauls ranging from no fish to about 5 fish. What does 5 fish caught in a trap tell you about a population of fish on a 5,000 or 25,000 or a 100,000 acre lake? Not much. My boss the district biologist realizes this and we have opted out of using trap net data to make any determination about the crappie populations for the lakes we manage.

Crappie are one of the most sought after fish in Texas and it is imperative that TPWD has some effective way of monitoring the populations in order to make recommendations such as appropriate bag and length limits, and how those recommendations are working. Based on our creel survey data we know that nearly 20% of all fishing effort on both Sam Rayburn and Toledo Bend is devoted to targeting crappie. We also know from our creel survey data that fishermen for each of these lakes spend over $1,000,000 a year to fish for crappie. Given both the recreational and economic importance of the state’s crappie fisheries, TPWD is working on better ways to monitor crappie, unfortunately, crappie are a difficult fish to monitor.

Because trap nets set off the bank yields few to no fish, TPWD has begun to evaluate if traps set in deeper water and if traps tied together (tandem nets) also set in deeper water will catch more fish. This year throughout the state across many lakes we evaluated which way of setting trap nets works best. As I write this article I don’t have access to all the data, so I don’t know what the results are statewide. Based on the results from our local lakes, there doesn’t appear to be much difference between the three different approaches.

There are other sampling gears available besides trap nets that are better at catching crappie. The best gear that I know of is an otter trawl. This gear is towed behind a boat and can be fished at different depths. The drawback to an otter trawl is that you have to tow it and if your sampling a lake with a lot of stumps and trees then likely you’ll spend more time destroying and repairing gear than catching fish. There have been studies where large, and I mean monster-sized trap nets have been found to be effective at catching crappie. The drawback with these is that they are hard to deploy and given the costs of these large nets we would be limited to just a few nets, and therefore would have trouble achieving the number of sampling sites required to get a good lake wide sample of the fish. Therefore options for using nets or traps are limited.

TPWD conducted a telemetry (radio tag) study to determine crappie movement patterns to see if we could target the fish more effectively with the trap nets we currently have on hand. To my knowledge and to give credit to the department this is the only telemetry study ever done to track crappie movement across seasons. There have been a handful of other crappie telemetry studies, but they have been limited to only a single season. In the TPWD study the goal was to determine if deploying trap nets at sites near known fish locations and at similar sites predicted to contain fish would result in increased trap-net catch compared to randomly selected sites. The end result was there was no difference in catch regardless of how it was determined to set the trap nets. Also, it was observed that individual tagged fish had a high variation of preferred water depths and distances from shore and were highly mobile with about 20% of the tagged fish being truly nomadic. Basically crappie movement and location throughout the year was more random than predictable.
 
However, a good way to keep tabs on how a crappie population and fishery is performing is to go directly to the fishermen themselves. As most fishermen who fish Sam Rayburn and Toledo Bend on a regular basis know, TPWD is constantly out there conducting creel interviews. Based on our creel data we feel like the crappie fishery for these lakes is doing pretty well. Over recent years, fishermen caught about three fish per hour. We also know that these lakes have good crappie growth rates with fish reaching legal size (10 inches) in two to three years, which is exceptional compared to other lakes in our geographic range.

As always, if you should have any questions concerning this article or have any other fishery questions please don’t hesitate to contact me at This e-mail address is being protected from spambots. You need JavaScript enabled to view it or call me at 409-384-9572. Good Luck and Good Fishing!

Dan Ashe is a fisheries biologist with Texas Parks and Wildlife Department. He has worked out of the Jasper, Texas field office since 2005 helping to manage east Texas reservoirs including Sam Rayburn and Toledo Bend. Dan has also worked as fisheries biologist in Puerto Rico, California, and Alaska but now calls Texas home.