Virginia study finds effects on gamefish to be minimal
Trotlining is an effective way to catch catfish — blues, channels, and flatheads — lots of them, and large fish, too. Although I may curse them when I snag unmarked trotlines when bass fishing and have little tolerance for untended and abandoned lines, I’ve also had a lot of fun fishing trotlines. An often-repeated concern is the effect of trotlines on game fish. A study on Virginia’s New River offers insights on this issue.
The New River offers anglers opportunities to catch walleye, trophy muskie, and trophy smallmouth bass in addition to channel and flathead catfish. True, muskie do not occur in the Deep South, and populations of Gulf Coast strain walleye swim in only a few rivers and impoundments in Mississippi, but these fish share their fish-eating habits with several Mississippi sport fish. Thus, the study — one of the few that has rigorously evaluated trotline catch — is applicable to our fisheries.
Virginia Tech and biologists with the Virginia Department of Game and Inland Fisheries fished trotlines from May through October in four areas of the New River. Half the lines were baited with live bullheads and minnows, and half were baited with cut gizzard shad. They were fished overnight in likely catfish habitat. Each trotline had 26 hooks, split evenly between 3/0 circle hooks and 2/0 J-hooks attached to alternate dropper lines.
A total of almost 3,700 hook-nights (a 26-hook trotline fished overnight would be 26 hook-nights) caught 338 fish, 80% of which were catfish. By-catch included 12 snapping turtles, 14 smallmouth bass, 18 walleye and two muskie.
Live baits ruled
Approximately 80% of all fish were caught on live bait. All of the muskie, smallmouth, and walleye — and 91 of 93 flathead catfish — were caught on live bait. Only channel catfish were caught with cut bait, and catch rates were low: 3.5 channel cats per 100 hook-nights with cut bait, about half the catch rate of 7.2 channel cats per 100 hook-nights with live bait.
Trotline catches of channel catfish remained consistent throughout the study. Flathead catfish were approximately two times more likely to be caught in August. Gamefish were more likely to be caught in June and October.
Channel catfish were more likely to be caught on circle hooks, but flathead catfish and gamefish were equally caught with circle and J-hooks. Of gamefish, 67% were hooked in the stomach or throat with J-hooks, compared to only 18% with circle hooks. Half the walleye and one third of the smallmouth bass were dead when the trotlines were retrieved.
Assessing the impact of trotlines on gamefish required estimates of recreational trotline fishing catch and effort. Field surveys for trotlines counted 32 active trotlines in the four study reaches.
Trotlines fished in rivers can be hard to spot. To get an estimate of trotline detection, some of the biologists set “dummy” trotlines, and then other biologists searched for the lines. Of the dummy trotlines, 90% were detected. I don’t know about New River trotliners, but some trotliners I know set their lines so they can’t be seen and rely on a grapple to retrieve the line. Likely, the 32 lines was an underestimate of trotlining effort.
Trotliners reported fishing trotlines with an average of 30 hooks per line and fished their lines an average of almost nine trips per month during the May-to-October time frame. Few anglers fished trotlines after October or before May. Applying this data to the estimated number of lines resulted in an average of 518 hook-nights per mile of river for the season.
The trotliners averaged 13.2 catfish per 100 hook-nights. Most used live bait. Gamefish catch averaged 1.3 fish per 100 hook-nights, or one gamefish for every 32 catfish caught.
Trotlines: not evil
Virginia biologists concluded that the relatively few gamefish caught on trotlines did not pose a large problem. High proportions of gamefish were gut-hooked with J-hooks. Circle hooks had the same catfish catch rate as J-hooks and were much less injurious to gamefish. Survival of released gamefish would benefit from use of circle hooks without reducing catfish catch.
As catfish management moves forward, some anglers are clamoring for regulations that will increase trophy catfish opportunities. Accomplishing this in fisheries with moderate to high harvest will require some combination of high size limits or limited harvest of truly large fish. Achieving the benefits of such regulations will require high survival of released fish.
The New River study found more than 73% of channel and flathead catfish were hooked in the lip, and less than 3% were hooked in the stomach or throat. It appears that hooking mortality of trotline-caught catfish can be relatively low. I think it is a safe bet that frequently tending trotlines will increase catfish and gamefish survival after release.