Catch and Release Fishing: How Many Fish Survive, and How to Do It

Catch and release fishing works, but not every released fish lives. A review of the science pooled 53 studies and 274 mortality estimates from fresh and salt water. On average 18 percent of released fish died; the median study found 11 percent, and the range ran from zero to 95. Almost all of that spread comes down to three things you control: where the hook lands, how long the fish is out of the water, and how warm the water is.

Exhausted rainbow trout held out of the water for 30 seconds survived at 62 percent, and for 60 seconds at 28 percent; with no air at all, 88 percent. Count to ten and the fish goes back.

How many released fish survive?

Each fish here was held or tagged after release. An angler sees none of these deaths, which is why release looks better from the bank than it is.

Saltwater, where the depth of capture joins the list:

What decides whether a fish lives?

1. Hook location. The 53-study review ranks it first: gut- and gill-hooked fish are where the deaths are. In the FWC snook trial, four of twelve deep-hooked fish died when the hook was removed. None of twelve died when the leader was cut and the hook left in.
2. Bait or lure, and the hook. Bait is swallowed; a moving lure is not, hence the Colorado trout split of 4, 21 and 32 percent. Circle hooks hooked bluefin tuna shallow 96 percent of the time, against 66 for J-hooks, and cut deep hooking in striped bass fourfold. Across the 2004 review they halved mortality; sailfish on J-hooks were 21 times more likely to bleed. The hooks hub covers circle hooks and the snell knot that makes them work.
3. Water temperature. Warm water holds less oxygen and raises the fish’s metabolism, so every other stress bites harder. The Oklahoma tournaments lost 3 percent in spring and up to 43 in summer.
4. Air exposure. Ferguson and Tufts’ trout were exercised to exhaustion first, as a fight does; the air finished them. Bass are tougher: at 70 °F (21 °C) and below, tournament largemouth survived up to 13 minutes in air, though they were slower to right themselves. Nobody has shown the same in summer water.
5. Handling. Dry hands and surfaces strip the mucus that protects against infection. Hanging a big fish by the jaw loads the jaw and the organs behind it.
6. Depth. A fish from 30 ft (9 m) or deeper, sent back down on a descending device, usually survives; tossed back, many float.

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What do you need?

• Circle hooks for bait fishing, or J-hooks with the barbs crushed flat with pliers (barbless hooks come off in one twist).
• A rubber or rubber-coated landing net; knotted nylon mesh strips the slime coat.
• Long-nosed pliers or a dehooker, and cutters for the line.
• A wet hand, a wet cloth, and a camera that is ready before the fish comes out of the water.
• A thermometer; the water temperature decides whether a release can work.
• A descending device for fish from deeper than 30 ft (9 m).

How do you release a fish?

1. Fish tackle that ends the fight fast.
2. Use circle hooks for bait and crush the barbs on lure hooks.
3. Keep the fish in the water while you get the pliers and the camera ready.
4. Net it in rubber, wet the net first, and leave the fish in the net in the water while you unhook it.
5. Wet your hands before touching it, and never lay it on a dry deck, rock or grass.
6. Unhook in the water if you can. With barbless hooks most fish come off with a twist of the pliers. A fish you will not photograph never needs touching: run a hand down the line and back the hook out.
7. Gut-hooked: cut the line as close to the hook as you can and leave it. Steel and bronze hooks rust or are pushed out; digging for the hook is what killed the snook.
8. Photograph in under ten seconds, held level with a wet hand under the belly, never hanging from the jaw.
9. Revive only a fish that cannot swim off. Hold it upright facing the current, or in still water move it gently forward, until it kicks away on its own. Pushing it back and forth drives water the wrong way through the gills.
10. Deep-caught fish: clip on the descending device and send it down before you do anything else.

How do you take the photo in ten seconds?

The photo is the one part of the release an angler wants to take time over, and that is where the damage happens. In Keep Fish Wet’s routine, the fish stays in the water while the camera comes out. The photographer calls “one, two, three,” the fish is lifted, and air exposure stays at ten seconds or less.

Hold it level over the water, not the deck, so a fish that kicks free lands in it. One hand goes under the belly behind the pectoral fins, the other around the base of the tail; no fingers in the gills. How to hold a trout has the grip for a big one.

Which tools help, and what spec matters?

The lip grip is easy to use wrong. Clamped on the lower jaw and lifted, it hangs a 10 lb fish from the joint of its jaw. Held level with the other hand under the belly, it keeps your fingers out of pike and muskie teeth, which is its job. The accessories hub has the net and plier picks, and the fishing thermometer page the $14 stream tube.

What about fish from deep water?

A fish reeled up from 30 ft (9 m) or more comes up with the gas in its swim bladder expanded: a swollen belly, bulging eyes, the stomach everted through the mouth. That is barotrauma. In a pressure-chamber trial, unvented red snapper survived at 67 percent from 100 ft (30 m) and 17 percent from 200 ft (60 m); vented, all of them did.

Venting works when done right. FWC specifies a hollow needle no longer than 1½ in (38 mm) and about ⅛ in (3 mm) inside. It goes in at 60–75 degrees just behind the tip of the pectoral fin, never into the stomach. Done wrong, it punctures the heart, liver or gut.

The descending device has largely replaced venting. The University of South Florida trial covered 1,030 red snapper and 190 grouper over 14 trips. Fish recompressed to at least 60 ft (18 m) survived two to two and a half times as often as vented fish. Recompressed to less than 60 ft, they did no better than vented ones.

Since July 15, 2020, every boat fishing for snapper or grouper in South Atlantic federal waters must carry a descending device. The same rule requires non-offset, non-stainless circle hooks for bait fishing north of 28° N.

A descender does not fix a deep hook, though. Off North Carolina, 79 red snapper were tagged from 125 ft (38 m) and sent down on descenders. Six percent of the jaw-hooked fish died, and roughly 88 percent of the deep-hooked fish were dead within a day. Walleye through the ice follow the same rule: predicted mortality was 1.5 percent from under 30 ft (9 m) and 15 percent from deeper, and 64 percent of the dead showed barotrauma.

How warm is too warm?

Every number in the tables gets worse as the water warms, and each fish has a temperature above which the honest choice is to stop.

Trout stress above 68 °F (20 °C): a 2008 Montana State study found trout released from warmer water far more likely to die. Montana now closes rivers to afternoon fishing after three days at 73 °F (23 °C). Walleye deaths on Mille Lacs climbed from none in May, under 68 °F, to about 12 percent in July and August.

Muskie are the extreme case. In the USGS pond study at 68–91 °F (20–33 °C), 30 percent of angled fish died against 11.3 percent of fish never caught. Maryland asks anglers to stop targeting them above 80 °F (27 °C). Bass are hardier, but the Oklahoma tournament numbers above follow the same curve.

Bass, pike, catfish, stripers, tarpon: what changes?

Bass and tournaments. Fish dead at the weigh-in run under 5 percent in B.A.S.S. events. The larger number dies later, from the livewell and the heat. Fresh water pumped through, ice in summer and a short bag time are the levers.

Muskie and pike. Hooks come out in the water, in a big net or a cradle, with long pliers or cutters. A cradle is the long sling net that keeps a 50 in fish horizontal from net to release. Lift it level and briefly, never by a lip grip on the jaw.

Catfish. The danger is to the angler, not the fish. The three spines are covered on how to hold a catfish, and a lip grip is the right tool for a big flathead.

Striped bass. ASMFC’s Addendum VI made circle hooks mandatory with bait on the Atlantic coast, and the 28–31 in slot sends most fish back; in summer water the Roanoke figures apply.

Tarpon, sharks, tuna. The big ones never leave the water; Florida requires tarpon over 40 in to stay in it. Tuna and some sharks breathe only while moving, so they are revived by idling the boat forward with the fish held alongside.

Mistakes that kill fish

• Lifting a fish by the gills, or hanging a heavy one from the jaw for a five-minute photo on the deck.
• Ripping out a swallowed hook, or fishing bait on J-hooks in summer for fish you mean to release.
• Throwing a fish back instead of putting it back, and throwing a deep-water fish back at all.

Where did catch and release come from?

Lee Wulff wrote in 1936 that “game fish are too valuable to be caught only once.” Michigan adopted catch and release for trout in 1952 to cut hatchery costs. It is mandatory for some species in Canada, and banned in Germany and Switzerland under animal-welfare law. Yellowstone National Park reversed it in 2011 and now requires anglers to kill invasive rainbow and brook trout in some waters.

In the United States it is the default for bass, the norm for trout on many rivers, and compulsory wherever a slot limit applies. Florida’s redfish may be kept only between 18 and 27 in, so every fish outside that slot is a release, planned or not. The fishing terms define slot, bag and possession limits.

When should you keep the fish instead?

Release is not always the conservation choice. A legal fish bleeding from the gills is a dead fish: keep it if the rules allow, kill it at once and count it in the limit. A legal fish throat-hooked on bait in warm water dies one time in three or worse by the studies above, and a fillet is a better end than a float.

A trout from 72 °F water, a muskie from 82 °F water, a snapper from 200 ft without a descender on board: the fix for each is not a better release but not making the cast.

FWC’s livewell rule: decide before the trip which fish you are keeping, and release the rest at once. Never hold a fish to let it go later if a bigger one comes; fish released from a livewell survive less often. Fishing for beginners covers the license-and-limit side of that decision.

The basics hub has the rest of the fundamentals, from knots to the species pages.

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The Water Temperature Fishing Chart. Take one water temperature reading, find it on the chart, and you know which of 26 freshwater fish are feeding today, where they are and what to throw. For your phone and the tackle box.

• The 26-fish chart: who's spawning, feeding hard or shut down at your reading
• Where they sit and what to throw at every band: bass, crappie, bluegill, walleye, catfish and trout
• The best hours at your reading, the cold front day by day, and the spawn calendar from ice-out to midsummer
• The three thermometer mistakes that make a reading lie (the first one is the surface)

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