Why Release Fish?
...By John Attard
The fisheries resources of our country are finite and coming under
increasing pressure, both due to pollution and over fishing. The
number of many species important to anglers has declined
drastically. It Is also becoming common for anglers interested in
the sporting aspects of fishing to release some fish that they
could easily keep for food, The benefits of releasing fish alive are
widely recognized. A released fish can live on to be caught later,
when they are bigger. They also continue to spawn, improving
populations in the longer term.
Numerous studies of freshwater fisheries have shown that most fish
survive catch and release. The limited amount of work done on
saltwater species has also shown a high survival rate of over 75 per
cent. The high Incidence of recaptures among tagged saltwater game
fish is another indication of the good survival rates of released
fish.
Surviving the Hook Wound
The site and severity of the hook wound obviously plays an Important
part in whether or not a fish will survive. Fish hooked in the gills
and gut are less likely to survive than those hooked less deeply.
However, even deeply hooked fish can survive if the line is cut and
the hook left in place. Removing the hook has been shown to reduce
dramatically the chances of a fish surviving. The type of tackle
used can influence fish survival. Many studies have reported that
fish caught on lures or files are more likely to be hooked superficially
in the Jaw or mouth and have higher survival rates than fish caught
on bolt.
Surviving Catch and Release
Fish become stressed as a result of capture and handling. This stress is
known to upset their blood chemistry. The result can be death either
immediately or later. Its condition and environment influence the
amount of stress a fish can tolerate. For example, some freshwater
fish are much less likely to survive if caught in warm water than in
cool water. As stress takes time to occur and its effects are
cumulative, it can be reduced by catching and releasing fish quickly
and handling them as little as possible.
If heavy tackle is used fish are less likely to become exhausted before they are landed and released. One of the major effects of stress is a reduction in the fish's normal resistance to infectious diseases. Fungal and bacterial infections are a common cause of death after release. Rough handling will increase the amount of damage done to a fish and create a greater chance of infection. As a fish's skin is particularly prone to injury, handling that causes a loss of scales and damage to the skin's
mucus-producing cells should be avoided.
Fish cut of Deep Water
Fish caught in deep water suffer problems similar to those of divers with 'the bends'. As a fish is brought to the water surface, the gases inside it are subjected to less pressure and therefore expand. This causes serious bleeding and the formation of large gas bubbles in the heart, blood vessels, gills and brain.
Unlike divers, some fish have the additional problem of the expansion of gas in the swim bladder. The swim bladder is a gas-filled sac that allows the fish to maintain neutral buoyancy. Many of the fish that anglers target have no way of venting gas directly out of the bladder and can only remove excess
gas by diffusing it into the blood. This slow process of gas diffusion restricts the speed at which the fish can move from deep to shallow water. As the fish is brought to the surface by the angler, the rapidly expanding gas in the swim bladder compresses its internal organs and sometimes forces the stomach out into the mouth. Although less damaging to the fish than the other effects of depressurization, this over inflation of the bladder can often stop the fish returning to deeper water, where the gases can
return to their original volumes and density. The fish is almost certain to perish if it is left floating on the water surface, unable to submerge.
Removing excess gas from the swim bladders of fish taken from deep water can greatly increase their chances of survival. Piercing the swim bladder through the body wail with a hypodermic needle or a sharp point can do this. It is effective and is commonly used when fish are being collected for breeding programs and aquariums. The swim bladder and gut lining can resist the pressure of the expanding gas for a short period only. For this reason the excess gas should be removed as quickly as possible to prevent the swim bladder from rupturing.
The tissue that protrudes from the mouth of a bloated fish is generally the stomach, which has been displaced by the expanded gas from the swim bladder. Puncturing this does not release the gasses in the swim bladder and does not help the fish return to its original depth.
For lively fish that are not excessively bloated, an alternative to piercing the swim bladder is to push the fish headfirst downwards into the water. This can help it to swim deep enough for the swim bladder to deflate as the water pressure increases.
Increasing the Survival Rates of Released Fish
Successful anglers have developed refined fishing skills that enable them to catch fish. Similarly, they can also acquire skills for releasing fish alive successfully. The following guidelines may help.
Fighting fish
Bring the fish in as quickly as possible, but make sure it is not in such a lively state that it will damage itself or you during landing or release. A fish exhausted by a long fight on light tackle can suffer greater stress than a fish caught on heavy tackle, and may be less able to survive. So great care must be taken when releasing fish caught on fine tackle, which is commonly practiced by Kingfisher members.
Unhooking and Handling
Flattening the barbs on hooks or using single instead of treble hooks on lures will make unhooking fish far easier.
(Barbless hooks are certainly easier to remove from hooked anglers) Avoid lifting the fish out of the water if possible, and unhook and release it quickly. A hook disgorger may be useful for removing hooks from the throat, but do not try to remove a hook from the gut or gills-cut the line. The few cents cost of a hook isn't worth killing a fish. If the fish has to be landed and there is no
danger of being spiked, bitten, cut or stung, it may be best lifted by a wet hand. A hand under and across the body of many fish allows them to be lifted without damage. Fish without teeth can be lifted by gripping the lower jaw, but only if you hold the fish vertically. Holding it horizontally may damage the mouth and neck.
If the fish has to be netted, a net made of knotless mesh will cause much less damage than the commonly available knotted polypropylene landing nets, which cause considerable skin damage and can blind fish by scarring the eye.
If you are putting a fish down to measure or photograph it or take a hook out, a smooth, wet surface will cause less damage to the skin than a dry rough surface. Covering the fish's eyes can help settle it down. If you are keeping only a few fish, try to select those that are bleeding from the gills or hove been hooked in the gut release those that are lightly hooked and have the best chances of survival.
Releasing
Fish can be held upright in the water and moved backwards and forwards for a short time to allow them to regain equilibrium before release. Avoid releasing the fish into warm shallow waters if deeper, cooler water is accessible. Fish that have been brought up from deep water have their chances of survival greatly increased if they are returned to deep water as soon as possible.
Deflating the Swim Bladder
Bloated fish from deep water should have excess gas released from their swim bladders as quickly as possible. The size of the swim bladder varies among species, but it is always located along the top of the gut cavity just below the backbone. It is usually in line with the top of the pectoral fin base and Just in front of halfway along the body of the fish. The swim bladder is best deflated by pushing a large gauge hypodermic needle (available over the counter from most chemists) or sharp point (for
example, a filleting knife) forward between the scales, then down through the side of the fish and into the swim bladder. If you miss the bladder the first time you can try again, as a small puncture wound will heal quickly. Sometimes you may need to expel excess gas by gently squeezing the fish's stomach. Once the bladder is deflated withdraw the point and promptly return the fish head first to the water.
Reducing Your Impact on Fish Stocks
Unfortunately even when fish are released with great care and skill there is still some risk of killing them. It is far better to try to catch only the right fish In the first place. You can sometimes avoid hooking undersized fish by moving to different fishing spots or by increasing the hook size. Changing rigs, baits or location may also allow you to target different species once your bag limit for one type has been reached.
Remember: fish for fun -fish for the future.