Non-traditional sampling provides insights
For many bass anglers, size matters, and several states have implemented management efforts to enhance trophy bass opportunities.
Evaluating these efforts is difficult, because very large bass are rare and infrequently collected in routine electrofishing or creel surveys. Results of a cooperative effort by biologists at the University of Florida, University of Georgia, the Wisconsin Department of Natural Resources, and the Mississippi Department of Wildlife, Fisheries and Parks may offer something of a solution.
The problem
Calling Panther Lake is a 400-acre state lake in Copiah County, that opened for fishing in 2006. It was stocked with crappie, bluegill, redear sunfish and channel catfish to provide a multi-species fishery. Florida bass were stocked to provide trophy bass potential, and forage stocking and a series of regulations have been used to help build a trophy bass population. Were the efforts working? What was the status of the trophy bass population?
Electrofishing is the standard method for sampling largemouth bass in southeastern states. Although providing important information about relative abundance, population-size structure, and recruitment, electrofishing has been shown to under-represent large bass compared to angling. While angler-provided data can fill in some gaps in fishery assessment data, biologists remain skeptical about angler data due to potential biases and validity. Could angler-caught fish caught under properly controlled conditions be a valid source of accurate data?
The study design
The bass population at Calling Panther was sampled by standard electrofishing in October and November of 2010 and 2012. Creel surveys were conducted from February through June of 2010, 2011 and 2012. All bass collected were measured for length and weighed.
Specialized angling designed to catch trophy bass but still be a standardized sampling method occurred from June to December 2011. The specialized angling consisted of two anglers trolling live golden shiners in all habitats in the lake where trolling was possible. All bass collected were measured for length and weighed. In addition, all bass collected were checked for tags, and a tag was applied if the fish was not already tagged to allow a mark-recapture population estimate.
The results
During 51/2 hours of electrofishing, 166 Florida bass were collected that ranged from 3.5 to 24.7 inches, with an average length of 10.7 inches. Only four of those bass were classified as “trophy size” —greater than 22 inches or approximately 8 pounds.
Anglers interviewed during 65 creel days caught 707 bass; 337 were harvested and measured by creel clerks. The harvested bass ranged from 5.5 to 26.8 inches and averaged 13.3 inches. Twelve trophy bass were measured.
The specialized-angler team fished 256 hours and caught 95 trophy bass. Twenty-nine of those fish were larger than 10 pounds, and the largest was 26.3 inches and 13.2 pounds. On average, it took the specialized anglers 2.7 hours to catch a bass greater than 8 pounds and 8 hours to catch a bass greater than 10 pounds.
Analysis of tagged and recaptured bass caught by the specialized anglers estimated of the trophy bass population at 150 fish or about 0.4 trophy fish per acre.
Implications
The specialized angling, which was designed to be a standardized sampling method — and thus, provide repeatable and comparable estimates — clearly was more effective than electrofishing and creel surveys for capturing trophy bass and provided useful information about a segment of a bass population that is poorly estimated by traditional sampling methods. As such, it is useful to assess trophy bass.
Although useful, this specialized angler-data approach is not a replacement for traditional sampling that provides information about bass population-size structure, recruitment and angler harvest. It’s effectiveness as a way to estimate the abundance of trophy bass is also limited to relatively small waters.
Statistically, the population estimate was relatively precise and indicated Calling Panther Lake had a large population of trophy-size bass. However, the accuracy of the population estimate is vulnerable to changes in catchability of the bass, a topic that has been discussed previously. If catchability of previously caught bass declines, as several studies have found, the specialized angling method will underestimate the abundance of trophy bass. If that is the case, Calling Panther Lake had a lot of trophy bass, at least in 2011.
