Are anglers getting better, despite bass becoming harder to catch?

Catching bass nowadays seems like a battle between the knowledge and skills of the anglers and the too-often unpredictable behavior of the bass. 

Scientific evidence points to bass becoming harder to catch. Studies in the 1980s attributed declining catch rates of bass in ponds to lure avoidance. A more-recent study found rapidly declining catch rates in weekly fishing trips on small impoundments in Mississippi and suggested the decline in catchability may be simply due to the presence of anglers or some component of the act of fishing. A 30-year Illinois study demonstrated that vulnerability to capture was a heritable, genetic trait that resulted in harder-to-catch fish. All this points to declining bass catch rates, but a recently published study has found anglers may be evolving faster than the bass. 

Testing efficiency

Illinois Natural History Survey fishery scientists used bass-tournament catch data to ask a simple question: are anglers getting better at catching bass? They compared tournament-angler catch rates (bass weighed in per angler in each tournament) to electrofishing catch per hour, the standard way biologists estimate relative abundance of largemouth bass. 

Electrofishing and tournament data were available for 969 tournaments on seven Illinois reservoirs for time periods spanning 2002 to 2016. The number of years of data for individual reservoirs ranged from five to 14.

All tournaments were single-angler events with a 5-bass limit. Using tournament weigh-in data to estimate catch rate has a potential flaw: it may not fully account for the total number of tournament-legal fish caught by anglers that weigh in a 5-fish limit. For example, an angler may have caught 10 legal fish but only weighed in the five largest.

While this possible data glitch cannot be ruled out, the average number of fish weighed in was only 1.15 bass per angler per tournament in events surveyed. Less  than 1% of all anglers in all tournaments caught four or five bass. Thus, underestimating angler catch was considered a minor issue.

On six of the lakes, angler catch rates increased over time, while bass relative abundance remained the same or decreased. On the seventh lake, angler catch rates decreased slightly, while bass relative abundance had a bigger decrease. Conclusion: bass tournament anglers are getting better at catching bass.

Implications

Bass might be getting smarter or evolving to be less vulnerable to capture, but bass anglers, at least in Illinois, seem to be winning the catch-me-if-you-can angler vs bass contest.

Several years ago, I analyzed trends in catch rates for anglers fishing in 311 large, top-tier, professional B.A.S.S.-sponsored tournaments. From 1972 to 2015, average catch rate in these tournaments increased at a rate of 0.06 bass per angler per day each year. The increase was statistically significant, but this is a tiny effect; at that rate of change, it will take almost 20 years for the average catch rate to increase by one bass per angler.

But in agreement with the Illinois results, it supports the conclusion that anglers armed with more knowledge of bass behavior and tremendous advances in boats, tackle and electronics are becoming more effective and efficient.

A downside?

I’m all about catching more bass, but there may be a dark side to increased angler efficiency that can affect management of black bass resources. 

Fisheries managers have long debated the value of angler-generated data. In the vast oceans, thorough, scientifically valid fisheries surveys are limited. Marine fisheries managers, instead, have long relied on the catch of commercial fishermen and operated on the assumption that greater catches mean-more abundant fish, declining catches warn of depleted stocks.

Scientifically valid fisheries assessments, like catch rates measured by electrofishing or nets, are more easily achieved in lakes and streams and, indeed, comprise a large portion of the work fisheries biologists do. Angler catch rate data is readily and relatively cheaply available and potentially useful, but to be useful for estimating fish abundance requires a very important assumption: catchability of the fish does not change.

If catchability declines with increased fishing, as has been found in several studies, declines in angler catch rates would be expected in a stable population. But a biologist assuming no change in catchability would interpret the declining angler catch rate as a depletion of the fish, a false conclusion.

But the opposite is true if anglers are becoming more efficient. In a stable population, increasing catch efficiency would result in greater angler catch in a stable population. Thus, the biologist assuming equal catchability would interpret the greater catch rate as an indication of an increasing fish population. Again, a false conclusion.

The worst-case scenario is a sufficient increase in angler efficiency to maintain high catch rates and mask a declining fish population.

These misinterpretations of angler catch rates are not worries as long as biologists continue to rely on on-the-water biological assessments, but they are concerns. Decisions on the status of a fish population based solely on angler catch data can lead to wrong conclusions.