If you are 'playing' a salmon you can significantly help its chances of survival by applying the information below. It is worth bearing in mind that less than 7% of smolts return as spawning adults, therefore, it is vitally important that the angler who is planning to return his catch is able to tackle this with success and confidence.
Ensure your rod is strong enough to subdue a fish quickly 1 minute per pound weight is a reasonable suggestion for time for landing a fish.
To avoid exhausting the fish it is prudent to use 15-20lb leader material where possible. Salmon are not renowned for being cautious about leader visibility.
When playing the fish it is the anglers aim to move the salmon out of the fast current into quieter water and have the angler positioned slightly below the fish.
By being below the fish you are able to ensure the salmon is battling the current as well as the anglers tackle whereas if the angler is upstream of the fish the angler is fighting the current and the fish. The fight time is therefore lengthened, perhaps un-necessarily. Make sure you pick a safe place to bring the fish to land. Once the fish is subdued bring it quickly to the bank for hand or net capture.
Landing the fish
Research has shown that exposing a salmon to air for even a short period, for example to take a photograph, can significantly reduce its chances of survival.
Keep the salmon in the water at all times. Do not at any time lift a salmon up by the tail as this can damage the tendons in the tail of the fish. Later in the season as the salmon nears spawning time, lifting a salmon by the tail can cause the egg sacs in females and milt sacs in males to rupture into the body cavity which can kill the fish in extreme cases thereafter. At all times support its belly whilst handling the fish in the water.
Use a large Gye-type landing net with knotless mesh which reduces damage to the fish's scales. It is wise to avoid beaching the fish as this again can remove protective mucous and scales from the fish which can lead to fungal infection.
The salmon that is being returned cannot be gaffed or tailed by mechanical tailer, as both implements cause considerable damage to the fish and were used historically when fish were being killed by the angler, in the days before the catch and release initiatives, that are currently in place through out many river systems in the UK.
Always handle the salmon with wet hands, or put on soft cotton gloves which need to be wet, when removing the hook from the fish's mouth or body if accidentally foul hooked. This prevents removing the fishes mucous which is the fish's first line of defence against disease and parasites.
It is very important that the fish is kept in the water after being captured and the fish should be supported from beneath, with the hook gently removed either by hand or by means of long-nosed forceps or hook releasing tool. If a hook is deeply embedded and cannot be removed, the leader should be cut close to the hook, as fish released with the hook attached will generally survive, and try not to squeeze the fish too hard, and never hold it by the gills at all times.
Releasing and reviving the fish
After removing the hook, or cutting the leader and leaving the hook or fly in the fish, then we should ensure that the salmon will be supported in the water, facing into the current to allow oxygen uptake by the fish's gills, and given sufficient time to the fish for it to recover. Hold the fish gently until it is capable of swimming away strongly, you will know it is time when you feel it starting to pulse and kick softly. If you release the fish and it turns 'belly up' then quickly capture the fish and support it again for a while facing into the current to allow more oxygen to be absorbed. When the fish is being fought there is lactic acid produced in the muscle tissue which creates oxygen debt and the muscles cannot function adequately Indefinitely.
Avoid weighing the fish if at all possible and if you have to then weigh the net with the fish enclosed in it, a Maclean net is suitable for this. Available here. A tape measure or a marked off wading stick can also be used to take the approximate length while keeping the fish in the water.
Alternatively, to accurately measure a big fish capture, an angler can run a length of monofilament or fluorocarbon from a spool, measuring from the fork of the tail to the nose of the fish and tie a knot. Continue to run the mono round the girth of the fish and tie another knot. By cutting the mono just above the second knot the angler has a length that he/she can measure against a tape measure later. FishFigure has been designed to make it as simple as possible for anglers to measure the size of their fish.
I am sure anglers will find this advice most helpful. Perhaps one day beats may supply this information to visiting anglers on small laminated leaflets with beat conditions. Survival rate is greater at water temperatures below 20°C so be aware of the necessity to quickly subdue and return the fish during the summer months.
Survival chances of released salmon
There has been research carried out by a number of fishery trusts that has shown that the survival rate of salmon caught and released may be close to 100% when we apply the above guidelines and practice.
Spawning success and viability of eggs may be unaffected in salmon caught and released in late autumn using the above guidelines, and they can recover within twenty four to forty eight hours of being captured and are able to spawn successfully.