Hooking mortality is an angling reality

I was walleye fishing the other night when my partner began to strip line from his reel and carefully feed it out the end of his rod. We were backtrolling. Dragging leeches. He'd had a hit. And now, as we waited for the fish to swallow the bait, we wondered aloud what it might be. Walleye? Another rock bass? Maybe nothing?

Time passed. After thirty seconds, Bob tightened the line, lifted his rod and set the hook. It was a 17-inch walleye. This particular fish was destined to die because we intended to dine on one of nature's culinary perfections -- a pan-fried fillet, wild rice and the sour drippings from a wedge of lemon.

Still, the fish may have died even if released. That's because hooking mortality is a reality. How many fish die as a result of catch-and-release?

That's hard to say because so many variables come into play. Mortality factors, include species type, whether the fish was caught on live bait or an artificial lure, water depth and temperature, hooking location, fish size, angler experience and more. Clearly, no angler wants to see a fish go to waste. Yet even when mortality rates are fairly high -- say 15 percent -- 85 percent remain alive to be caught again and perhaps produce future generations of fish.

These benefits aside, hooking mortality is atop a wave of attention for a number reasons. On the international level, it's a cause within the animal welfare movement. Nationally, fish survival is an important component of high profile catch and release fishing tournaments. And in Minnesota, mortality is a major management issue because anglers release so many fish either voluntarily or to comply with conservation regulations. Moreover, hooking mortality snagged a fair amount of media attention last year when the walleye bite on Mille Lacs was 10 times above average. The fantastic fishing resulted in hooking mortality estimated at 228,000 pounds of the 382,000-pound total kill.

Was mortality really that high? Is there anything an angler can do to decrease it?

Those questions are the subject of research currently under way by DNR fisheries staff at Aitkin. Though a formal report is many months away, preliminary findings from data collected this spring and summer suggest that walleye mortality at Mille Lacs, previously set at 6 percent for walleye more than 13 inches and 10 percent for walleye less than 13 inches, is potentially less than that. In May, for example, none of the 145 walleye that were collected died within the first five days after being released. In June, the number was five of 244. In July, mortality was 14 percent based on a total sample of 181 fish.

These findings are based on a study in which DNR staff collected walleyes caught by anglers and then observed the fish for a number of days by placing them in holding pens that extend to the lake bottom. This research will continue into October. Research that results in a lower overall mortality estimate -- especially lower mortality in May and June, when the highest proportion of walleye are caught -- would translate into less fish dying from catch-and-release and more living to be caught again.

Another DNR research project under way at Mille Lacs aims to determine the difference in the rate of gut-hooked walleye caught and released with a standard fishing hook and those caught and released on a circle hook. A circle hook points inward. This design tends to increase hook sets in the jaw and decrease hook sets in the esophagus. Tom Jones, the DNR's Mille Lacs large lake specialist, has been catching walleye on both kinds of hooks the past two years and this is what he's learned:

* 45 percent of walleyes caught with a leech and circle hook are hooked deep in the mouth compared to 53 percent with a standard hook. Both percentages are based on waiting 20 seconds after the bite to set the hook. The difference in percentages, based on about 75 fish, suggests a switch to circle hooks would not result in any great saving of walleye;

* Regular hooks, Jones noted, injured fish more frequently than circle hooks, but circle hooks slipped out of the fish's mouth more frequently. Circle hooks, therefore, did reduce internal injuries to walleye but largely because circle hooks hooked fewer fish.

What are the practical applications of this and other DNR hooking mortality research for anglers?

One, most hooking mortality is the result of puncture wounds to organs inside the fish. Therefore, the longer an angler waits between the bite and the hook set the greater the likelihood the fish will swallow the bait deep and potentially suffer life threatening injury.

Two, the jury is still out on barbless hooks. Research findings are mixed. Barbless hooks allow anglers to handle fish more quickly yet study results vary as to the hook's effect on short-term mortality.

Three, infections kill fish, be they viral, fungal or bacterial. Frequently these infections are related to puncture wounds or the removal of the fish's protective slime. Like fish, humans are unlikely to die from a small puncture wound. On the other hand, you and I could die from an infection that results from stepping on a nail or some other small, deep wound. Similarly, a walleye that loses its protective slime while flopping around on the carpet of a boat could die from a fungal infection even though it was healthy when released.

Four, fighting a fish quickly is better than fighting it slowly. That's because the longer a fish fights the greater the lactic acid build-up and the greater the oxygen debt of the fish. Ironically, big fish are more likely to die from oxygen debt than small- or medium-sized fish because the ratio of their smaller gill size to body mass ratio. This ratio is why anglers who catch a big fish sometimes have a hard time reviving it to the point that it successfully swims away.

Finally, we all share a personal responsibility for fish mortality. Catch-and-release is great. It's natural resource conservation.

Still, we anglers must accept the fact that healthy-looking fish sometimes die. And more importantly, we have a responsibility to minimize that loss so other anglers can gain from our good intentions. For in the end, the angler who catches and releases many fish may kill more than the angler who simply harvests a few for supper, stows the rod and motors back to shore.

To reduce mortality, your local DNR fisheries managers ask that you remember the following:

* Set the hook quickly. A quick hook-set usually puts the hook in the fish's mouth, where it does little damage. Don't tear hooks from a fish's mouth.

* Wet hands before handling the fish. This will minimize the loss of the fish's protective mucous.

* Cut the line if you cannot easily remove the hook without damaging the gills or throat. A fish has a good chance of surviving if released quickly. Leave at least an inch of line hanging out the mouth. This helps the hook to lay flush when the fish takes in food.

* Don't keep the fish out of water for long periods. If possible, unhook the fish without placing it in a net or lifting it from the water.

* Don't place fish you plan to release on a stringer or in a live well. Confinement adds significant stress to the fish and decreases their chance of survival upon release.