Bits & Pieces: Unpacking Angler Impact Across Species and Systems

Science in Action: Recycling Muskies

Catch and release (C&R) has been the norm for muskie anglers for at least a couple decades, and muskie fisheries have rebounded. Muskie fishing is about size, and C&R is the best way to keep fish in the population to grow larger. But how well does it really work? A multi-year Ohio DNR mark-recapture study of more than 4,100 tagged muskies in 1,033-acre Clearfork Reservoir and 1,011-acre Leesville Lake offers insights.* And a couple surprises.

Analysis of self-reported angler catches suggested that anglers would be expected to catch and release one quarter of the muskie population in each reservoir annually. This is a catch rate higher than the 11 to 22 percent catch rate estimated for two Minnesota fisheries, but lower than the 57 percent catch rate in the James River, Virginia. It may be important that both muskie and muskie-angler densities are very high in the James River.

Annual survival of C&R muskies was 58 percent at Clearfork and 67 percent at Leesville. These rates were lower than the annual 67 percent survival of at-large muskies—fish collected only with agency gear and not caught by anglers—at Clearfork and 87 percent at Leesville.

The low estimated survival of muskies in Clearfork was possibly influenced by fish escapement over the dam, as suggested by the lower survival of fish caught only by agency gear. Nevertheless, lower survival rates of C&R muskies than at-large fish indicate some fishing mortality. Further,  muskie survival estimates in this study were well below the 100 percent survival assumed by many anglers and the nearly 100 percent survival estimated in short-term studies in Michigan and Ontario. The Ohio study assessed long-term survival and also included the fate of fish captured during warm-water periods, conditions that have been shown to reduce muskie survival.

Recycling rate—the subsequent capture of previously C&R muskie—was 15 and 18 percent in the two reservoirs. Only 2.5 and 3.4 percent of recycled muskies were caught again in the same year. In comparison, within-year recapture rates ranged from 5 to 14 percent in two Minnesota lakes. In both Ohio reservoirs, the median recycling time—the elapsed time of half the repeat captures—was 1.1 years, and recycling time was more than 2 years for 25 percent of the catches.

Statistical analysis possible by this powerful, multi-year study allowed a unique insight: the probability of a captured muskie being recycled was 1.4 to 1.6 times greater than the probability of catching an at-large (a previously uncaught) muskie. Vulnerability to capture (catchability) has been well studied in largemouth bass and found to have both learned and genetic components, but catchability of muskies has received little attention. The only other study I am aware of was done by Wisconsin DNR biologists in Escanaba Lake. In that study, researchers analyzed 13 years of angler catch data and found only a very slight decline in trip success as the portion of the muskie population captured increased.

In the Ohio reservoirs, the rarity of recaptures within the same year of initial capture suggests learning may affect recapture. But also important, the greater likelihood of recapturing a previously caught muskie than of catching an at-large muskie suggests inherent—that is, genetic—differences in catchability among individuals in the muskie populations.

—Dr. Hal Schramm

*Page, K. S., C. P. Wagner, and E. Lewis. 2024. Using mark-recapture techniques to evaluate catch and release, recycling, and associated survival probabilities of stocked muskellunge at two Ohio reservoirs. N. Am. J. Fish. Mgmt. 44:1197-1211.

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Field Research: Effects of Electronics on Fishing Success

The use of increasingly advanced sonar systems has been a controversial topic among anglers of varying philosophies, as well as a source of concern for fishery managers charged with safe harvest oversight. Over the past five years, “live action” and “forward-facing” units have increased the ability of anglers to locate and target fish, particularly those in deeper open water.

To evaluate these effects in real-world situations, a team of biologists studied angler behavior, success, and fishing satisfaction on nine lakes in southern Wisconsin (Dane County) and 18 lakes in the sparsely populated northern part of the state (Vilas County) in 2022.* They conducted a creel survey, talking to anglers both before their trip and after they were done, during ice-fishing and summer seasons.

Pre-trip data included target species, expected catch, and trip length.

Afterward, they inquired about use of technology: type of electronics if any (sonar systems, underwater cameras, GPS/chartplotter), spot-lock-style trolling motors, trip duration, catch, and degree of satisfaction with their trip and satisfaction with their catch once they were done. For summer trips, anglers were also categorized as boat or shore anglers. They did not, however, differentiate among type of sonar systems (2D, 360-imaging, or forward-facing).

They conducted 1,227 angler interviews, though not all contacts included pre-trip and post-trip data. Almost 3/4 of contacts were in Dane County, split between 45 percent ice anglers and 55 percent in summer. Overall, about 80 percent of ice and boat anglers used technology, while, not surprisingly, few shore anglers did so. Ice anglers targeting panfish were significantly more likely to use technology (sonars and cameras) than those pursuing gamefish (primarily pike and walleyes).

In all situations, most anglers failed to meet their expectations in terms of catch success, and use of technology had no effect on this disparity. Other research has found that anglers tend to rate their skills highly, which can inflate their expectations. In considering their overall trip, anglers using technology had higher expectations but ended up with lower satisfaction than those who fished without it. The researchers theorize that viewing fish on sonar and failing to get them to bite might prove disappointing. Sociological implications proved interesting, but they noted that fear of overfishing may be unfounded, at least in those types of waters.

—Steve Quinn

*Kerkhove, A. M., A. Trudeau, O. P. Jensen, D. A. Isermann, P. A. Dombrowski, A. M. Latimer, and Z. S. Feiner. 2024. Understanding the role of recreational angling technology in angler expectations of catch, trip catch, and angler satisfaction. Fisheries 49(10): 463-474.

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Habitat Connections: Black Bass in Tennessee River Reservoirs

To evaluate the biology and conservation status of black bass species in the Tennessee River system, Dr. Steve Miranda of Mississippi State University analyzed 21 years of electrofishing collections made on nine reservoirs there.* This river, the fifth largest in the U.S., flows from the Appalachian Mountains in a generally westward direction to its confluence with the Ohio River. Its impoundments are among the most popular for bass fishing, as well as for other species, notably catfish and crappies.

The study sample included 43,243 bass of all sizes—67 percent largemouth; 14 percent smallmouth; and 19 percent spotted bass. Note that these collections predated the recent revision of spotted bass genetic status, so the spotted bass sample was dominated by what’s now known as Alabama bass.

Many samples contained multiple bass species. Electrofishing catch rates of largemouth were highest; lowest for smallmouth, with spotted bass intermediate. Overall, when one species was more abundant in a reservoir, or portion of it, they typically were found in more types of habitat as well. Conversely, lower abundance tended to coincide with fewer types of occupied habitat.

Miranda noted that these nine contiguous reservoirs offer rather similar habitat characteristics, as the Tennessee River flows steadily through their basins, covering 637 river miles as it drops 460 feet in elevation. Largemouth bass have higher fecundity and mature at a younger age than smallmouths, with spotted bass intermediate. Largemouths were largest in size as well, with spots smallest on average.

He pointed to two important long-term developments that could shift relative abundances of these species: reservoir aging and climate change. With largemouths suited to a larger variety of habitats including eutrophic conditions, and also tolerant of warmer water, they may tend to thrive in coming decades. Smallmouths have the lowest warm-water tolerance of the group and these waters represent their southernmost distribution, so further warming could limit smallmouth numbers and habitats they’re found, in comparison to largemouths and spotted bass.

—Steve Quinn

*Miranda, L. E. 2023. Abundance-occupancy patterns of black bass in an impounded river. Fisheries 48(1): 29-37.

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