AUSTIN – With more people heading out to the water, recent reports have shown anglers aren’t catching bass as often despite healthy fish populations in lakes. The Texas Parks and Wildlife Department launched a new study tracking the movements and behaviors of largemouth bass at Toledo Bend and Lake Fork to try and figure out why.
“Our goal is to provide the best fishing opportunities possible for our anglers,” said Jake Norman TPWD fisheries biologist, who is co-leading the study. “I think studying the actual behavior of bass and passing this information on to the anglers is a great way to do that.”
This unique study uses radio transmitters implanted in the fish to track their movement and habits on both lakes to see if increased traffic and angling on the lakes has influenced their behavior. The study began in May and a total target number of 50 fish are slated to be tracked. Researchers plan to track 20 fish on Toledo Bend and 30 on Lake Fork. The expected life span of the transmitters is 1.5 to 2 years so researchers anticipate it may take up to 2.5 years to complete the study and generate the results.
“Historically, most studies were designed with the intent of gaining knowledge to better manage a fish population,” said Todd Driscoll, TPWD fisheries biologist, who is also co-leading the study. “This specific telemetry study is focused on fish behavior and how that information can directly help anglers and potentially guide them in how they approach fishing the lake.”
Lake Fork went through its worst drought on record from 2010-15, resulting in thousands of acres of lost shallow water habitat. The reservoir filled in 2015, leading to thousands of acres of newly flooded shallow habitat and strong year classes. However, the high catch rates of smaller fish from 2015-2018 didn’t seem to translate into more fish in the 16- to 24-inch range in 2019.
Despite anglers reporting a reduced amount of slot fish, the electrofishing data biologists gathered has remained consistent.
“This is where the project started to come together,” said Norman. “What better way to answer this question than to track fish movements over the course of a year and have better answers to where slot fish potentially disappear?”
At Toledo Bend, bass fishing quality was exceptional from 2011-16, leading the Bassmaster organization to name it the best black bass fishery in the world for both 2015 and 2016. As expected, anglers flocked to the lake between 2016 and 2018 following the national publicity.
In 2018, anglers began reporting a decline in catch rates and many assumed that these drops were due to a waning population. TPWD electrofishing surveys showed a decline in the bass population. However, the question was raised if increased fishing activity on the lake was altering the behavior of the fish and also contributing to the decrease in angler catch.
The study happening on Toledo Bend and Lake Fork will focus on seasonal habitat use, movement and home range of largemouth bass and see how it correlates with angling activity. It will also explore the effects of boat motor noise and angling activity on fish behavior.
Few studies have examined boat and engine noise effects on fish behavior. The effects of boat motor noise on largemouth bass behavior outside of the spawning season has not been studied.
On both lakes, biologists will monitor the movement patterns of individual largemouth bass ranging from 16 to 24 inches in length. With the ability to collect basic location and movement data, researchers will be able to document the habitat and structure each fish is using. This information could potentially help identify behavioral trends throughout the year. Once a fish is located, the plan is to monitor its immediate behavior from overhead motor and sonar noise to see how these common sounds reposition or scatter fish.
The bass will be monitored at least every two weeks by boat using a handheld radio receiver and antenna. Each fish had a small radio transmitter surgically implanted in its abdomen.
“Learning and practicing this procedure was a fun and nerve wrecking component of this project,” said Driscoll. “There are several steps and precautions to follow in order to ensure a successful surgery.”
The tracking system will be used to pinpoint the location of the fish, and researchers will look to create a waypoint. If physically visible, they will attempt to record the habitat it’s in or near and using live scanning sonar, try to determine if the fish is alone, or part of an aggregation and if the fish is suspended in the water column, or bottom oriented. They also hope to record any structure the fish appears to be relating to and then continue to track the fish with both the radio receiver and live-scanning sonar, to monitor how the fish reacts to boat noises and if possible, how the fish reacts to direct fishing pressure.
So, what should an angler do if they happen to reel in one of these fish?
“On Lake Fork, the angler is encouraged to take a few pictures, record the external tag number (pink tag near dorsal fin) and release the fish,” said Norman. “They can contact me directly on my cellphone, which is located on the tag, and report the catch. However, if the fish is legal to harvest or retain (more than 16 inches in this case) it is entirely up to the angler whether they release it or not. If harvested, I would like to attempt to recover the transmitter and if the fish is retained for a tournament, I would like to make attempts to release the fish near where it was caught, if feasible.”
Anglers can also contact Driscoll if a fish involved in the study is caught on Toledo Bend.
“I have my cellphone number on the pink Floy tags attached to the fish,” said Driscoll. “Toledo Bend is managed with a 14-inch minimum length limit, and all tagged fish are legal for harvest. However, I would encourage anglers to release these fish where they caught them.”
Check out more information on Lake Fork and Toledo Bend Reservoir on the TPWD website. The study is being funded by the Sport Fish Restoration Program.
