WFFD Tries New Tactic For Stocking Delta Bass
Each year the Alabama Wildlife and Freshwater Fisheries Division publishes a B.A.I.T. (Bass Anglers Information Team) Report that identifies bass fishing success through reports from various bass tournaments around the state. The 2008 report, which is the latest available, shows the Mobile-Tensaw Delta ranked last in four of the six categories that determine the statewide rankings and next-to-last in another.
The Delta finished in the middle of the pack in only one category – percent success. Facts from the report indicated a total of 249 anglers caught 541 bass that averaged 1.28 pounds each. More than 87 percent of Delta bass anglers weighed in at least one fish during 2008. For bass fishermen, size does matter, and not one bass that weighed more than 5 pounds was landed during any of the tournaments that turned in reports.
For fisheries biologists with the Wildlife and Freshwater Fisheries Division (WFFD), the Delta has resisted change. Attempts to introduce Florida bass DNA into the population have proved fruitless. WFFD stocked Florida-strain bass from 1988 to 2000 with more than 236,000 fingerlings released into the Delta, but the brackish water proved to be a hostile environment for the Florida bass. There is no evidence now that any of the DNA from the Florida bass has survived.
“We skipped one year, so we had 12 years of stocking Florida strain,” said Dave Armstrong, fisheries biologist at the WFFD’s Spanish Fort office. “It never made a dent.”
Obviously, WFFD needed a new approach, and about 10 years ago Monroe County Lake became a site to evaluate how well Delta bass would perform in a more typical largemouth bass habitat. The lake was drained and cleaned out completely and restocked with Delta bass to see if they would really get bigger grown in fresh water. So far they have.
“Right now, you can go to Monroe County Lake and catch them up to eight pounds. You don’t see that in the Delta,” Armstrong said.
Delta bass appear to have a unique identity in the black bass world. During the last eight years WFFD contracted with Auburn to conduct two extensive studies of the Mobile Delta largemouth bass population. One notable finding was that Delta bass were genetically distinct from both northern and Florida largemouth bass and this is likely an indication that this population has adapted over time to the challenges it has faced in an estuarine habitat which is marginal for this species. WFFD Fisheries Biologists determined that the best strategy for increasing the potential for larger growth of largemouth bass in the Delta would be to work with the fish that were native and acclimated to this habitat.
Last year a new multi-year research study was initiated to begin investigating how to best manipulate the existing stock of largemouth bass in the Delta to enhance the inherit traits of the population to produce larger size individuals.
“One of the primary goals was to look at a bigger fingerling being produced that would have better survival and express their genes across the Delta population,” Armstrong said. “The idea was that instead of the 1- and 2-inch bass we stocked with the Florida strain, we’d try to stock with a 6-inch (sub-adult) bass. We won’t stock as many but we should get a better survival rate with a bigger fingerling.”
Adult Delta bass were collected from Monroe County Lake and spawned at the Marion Fish Hatchery, and then their offspring were reared in hatchery ponds through the summer and fall to a larger advanced size fish.
Each hatchery raised fingerling was tagged by injecting a tiny magnetized stainless steel wire tag into the snout of each fish. These tags can later be detected by the use of a specialized metal detector without having to harm the fish. There are no external tags, so anglers will not be able to tell if they hook one of the released fish.
One of the downsides of stocking these bigger fingerlings is that it’s expensive.
“It takes a lot more space and money to grow the larger fingerlings,” Armstrong said. “On a large scale, this would be very difficult.”
With the first annual stocking for this study, a couple of weeks ago, WFFD stocked 3,376 sub-adults in Three-Mile Creek in Mobile County and 671 in Byrnes Lake in Baldwin County and 200 in Monroe County Lake. Armstrong said WFFD fisheries biologists will sample bass in the spring and fall for several years to keep track of the released fish.
The fish put in Monroe County Lake were the cream of the crop, averaging from 8 to 12 inches. Each fish released in Monroe County Lake had PIT (Passive Integrated Transponder) tags injected to allow fisheries biologists to track growth rates for each individual fish. Each year of this project, the fastest-growing offspring will be stocked back into Monroe County Lake with the remainder being stocked at selected sites in the Delta.
Eventually, through this process there will be many tagged fish in this 90 acre lake that will have a known “pedigree” characterized by fast growth, capable of reaching older ages and subsequently reaching larger size.
“We’ll be able to look at growth advantages of these selected bass,” Armstrong said. “In reality, part of the project is to develop a new line of brood stock, which takes many years. Unlike a hatchery, at Monroe County Lake the fish will be affected by angler harvest.”
Armstrong said it will take a minimum of three years to determine if stocking the larger fingerlings has been successful in the Delta. However, establishing a new line of Delta bass brood stock at Monroe County Lake is an achievable (but much longer term) goal.
“One of the (potential) shining stars of this program is developing an improved stock,” he said. “Building a new stock of hatchery bass is a big deal. Like developing the Marion strain at Marion Fish Hatchery, it took about 30-40 years to develop that strain. It’s a fast-growing, big-bodied bass with an aggressive nature and is considered an excellent bass for small impoundments.”
Bass that spend their entire lives in the harsh Delta environment tend to be abundant and somewhat stunted in growth with a relatively short life span. The WFFD-funded studies done by Auburn University indicate Delta bass are negatively affected by salinity and high amounts of nutritionally inferior blue crabs in their diet. With that said, there is an unavoidable uncertainty involved with this project. There is no guarantee this effort will result in superior growth in Monroe County Lake or the fish stocked into the Delta.
“We’ll probably start checking bass for tags at tournament weigh-ins in 2012 ,” he said. “We’ll track the return and growth rates compared to the resident bass. Our expectations are that we will hopefully see bass that got a better start than their wild counterparts that first year. Whether they attain better growth compared to the resident bass remains to be seen. We’ll track them through each year class and see if they do attain better growth rates because of their genetic predisposition and/or if because they were held in a protected, controlled environment for eight or nine months.”
PHOTOS (by Dave Armstrong): Maurice Winton opens the valve to release the large bass fingerlings into Byrnes Lake in Baldwin County. Richard Deavours scoops up bass fingerlings at the Marion Fish Hatchery to transfer to the Mobile-Tensaw Delta.