Catch and Release

Catch and release has been around for a long time and is now very widely adopted in many fisheries around the world, most famously in the USA and New Zealand but increasingly in countries that traditionally catch trout for the pot such as France, Spain and Italy, where ​‘no kill’ zones are now designated in some rivers. One notable exception is Germany where angling on a catch and release basis is not permitted. Many of the clubs and fishery owners that we work with now mandate catch and release or are moving towards 100% catch and release and reduced stocking with farmed trout. 

For us at the WTT, and for many anglers, the question is not whether catch and release is a good thing, but how well it is done. 

This web page is intended to give a guide to best practice catch and release as well as some of the impacts. The information applies to resident brown trout and sea trout. 

Catch and release – the quick guide

• Use barbless hooks
• Bring the fish to the net as quickly as possible
  
• Keep the fish in the water
• Handle as little as possible, and always with wet hands 
• Do not squeeze – it damages internal organs
• Remove the hook using forceps if necessary
  
• Avoid contact with the bank or gravel as this removes protective slime
• Release the fish by pointing its nose into the current so that water is flowing over its gills
• Support it gently until it swims away

This summary is available as a waterproof card from the WTT shop. 

The card also has a table to convert trout length to weight on the reverse — so you can measure the length of your fish while it’s resting in your net, and use the table to convert that length to an estimation of weight, based on the trout’s condition.

The video below is a good summary of best practice catch and release.

Getting trout to the net

Use a net! For anything but very small fish, a net is the most effective way to perform catch and release with minimum damage to the trout. 

The objective is to get the fish to the net and back into the water as quickly as possible to maximise its chances of survival. Evidence shows that a prolonged ​‘fight’ increases the stress on the fish and reduces its chance of survival, especially if water temperatures are high (see below for more on this).

Use tackle appropriate for the situation and the size of fish you expect so that you can land the fish quickly. A 1 or 2 weight rod and very fine tippet is perfectly good for small wild trout, but many rivers now hold wild fish of 2lb and upwards and for this you need a setup that allows you to control the fish and bring it to the net quickly. A 4‑weight rod and 5X / 4 or 5lb tippet is a good start point. 

Keep the trout upstream of you if at all possible so that the river is helping you and not the fish. Be prepared to move to keep the trout upstream of you. Pulling a large fish against the current is more likely to result in a lost fish.

Don’t have a tug of war. Learn how to throw the fish off balance by moving the rod left and right to create side strain. Bring the fish into slack water to net it. 

It can help to crouch down as you bring the trout to the net so that the trout is less alarmed. They do tend to spot you at the last moment so be prepared!
As soon as the trout’s head is up, get the net below the water. Bring the trout to the net (not the net to the trout), ideally using the flow of the river to help you. 

For a lot more useful information on this topic, read Don Stazicker’s article ​‘Fish Fighting Skills for Catch and Release Fishing’.

The video below shows tenkara angler with a soft rod landing a large trout in fast water without a dramatic battle.

The effect of temperature

Trout (and grayling) are cold water fish and brown trout prefer water temperatures of less than 15C, they will start to struggle at 20C and die at 25C. The amount of oxygen in the water declines as water temperature increases, which means that being caught and landed is far more stressful for trout as water temperatures rise, and the chances of survival reduce. 

During warm summers with low flows, especially in rivers with little shade, water temperatures can quickly become too high for survival following catch and release. It is the water temperature not the air temperature that matters. A nice cool summer evening for fishing for you may still be a lethal water temperature for the trout, so take the temperature of the water before you fish and if it is at or around 20C, it is better not to fish. 

For more information on temperature and trout (and salmon), click here.

Holding trout for photos 

Cradle the trout just behind the head and hold the wrist of the tail firmly. Keep the trout in the water, lifting it out very briefly to just above the water to take the shot. Always support larger trout with two hands.

Holding a live trout for a photo can be tricky (especially if it is a big trout) and it is tempting to squeeze the fish to get a good grip. However, you could be inadvertently killing a fish that you are planning to release, because the place where most people will hold and squeeze a fish – just behind the head – is where the heart and liver are located. A fish subjected to squeezing of the heart may swim away but die soon after. 

This article by Tony Bishop of Bish and Fish New Zealand gives a very good description of the problem and describes how to hold a fish for that triumphant photo!

For large fish, it is also important to support the fish so that the back isn’t sagging. Supporting the fish at the vent and the pectoral fins is the best way to achieve this. Those points generally do not indent and put pressure on the internal organs because of the skeletal and musculature structure.

How long should it be out of the water? Ideally less than 10 seconds, certainly not minutes – if water stops dripping off the fish, it’s too long. If you need another shot, put it back into the net in the water to recover for a minute or two and try again.

How big is it? 

You can use a weigh net but don’t hoist the fish out of the water, supported only by the net, for more than a second or two. An alternative is to measure the length of the fish from head to tail using a measure stuck on to your rod. You can measure a trout against your rod easily without removing it from the water. The length of the fish can be converted to weight using these tables (in old fashioned inches and pounds) that take into account the condition of the fish. 

Letting it go

Point the nose of the fish into the current so that water is flowing over its gills.
You need a reasonable flow but not a torrent, and clear water, not water full of sediment. If you have done a really good job, the fish will instantly kick away. If the trout is stressed, it may take a minute or two to recover before swimming off. Hold the trout gently in the water until it moves off. 

Do not move it backwards and forwards. Water needs to flow through the mouth and out over the gills for the fish to breathe. The unnatural backwards movement pushes the delicate gill lamellae in the wrong direction and hinders their breathing, potentially damaging the gill, causing additional stress and prompting the fish to swim away before it is actually ready.

A summary of things to avoid: 

• Holding the trout out of the water for more than a 10 seconds. A gasping trout is ​‘drowning’ in air. 

• Laying the trout on grass or shingle or any surface away from the water. Trout are covered with slime which protects them from disease, particularly fungal infections, and contact with surfaces (including rough nets) will remove slime.

• Touching the trout with hot, dry hands as this will also remove slime. Wet your hands before handling. 

• Don’t squeeze the trout or get your fingers near or in the gills.

• Don’t have a wrestling match to remove the hook. Barbless hooks should come out easily but if you can’t easily remove it then cut the leader close to the hook and leave the hook in place. The hook will come out naturally in time and this is better than squeezing the trout and holding it out of the water. 

Does catch and release make a difference to the number and size of trout?

By not killing fish, it seems self-evident that you will be removing one pressure on a trout population so there should be more fish. It is also likely that there will be more large fish too. And large hen fish will lay more eggs so that means more fish……

Anecdotally, we hear from clubs that have stopped stocking and introduced 100% catch and release that initially the numbers of small wild trout increase, but also that over time the average size of trout caught increases and specimen trout return, as one might expect from a healthy, balanced population.

This is rather simplistic, and there is one big caveat – that the population will increase to a point which will be limited by the available food and habitat – and lots of other factors which come into play in the complex natural environment. 

For a science-based summary of the impact of catch and release, take a look at these slides, based on research in the USA cited by Robert Behnke in his book About Trout. 

The contribution of big old trout 

The suggestion that killing off the larger/​older fish on the basis that they are going to die soon anyway needs re-evaluating. 

Trout often have very distinctive spotting patterns and this has allowed an increasing body of photographic evidence that shows trout get caught and re-caught over time. This evidence suggests that some trout live longer than we might have thought – 12, perhaps 14 years may not be that unusual. Some examples are given in this article by Dennis Moss. 

One example given is the case of a trout first caught by Trevor Ashton on a chalkstream in 2004 weighing 3lb 2ozs and caught again by him in 2011 weighing just 2oz more. This fish was in good condition, and assuming it was already five or six years old when it was first caught, it must have been around 12 years old when caught for the second time. 

Large old trout will typically be a small proportion of the total population, but large hen fish are potentially contributing a huge amount to that population because of the large number of eggs that they produce relative to smaller fish. In a Dorset stream, one study suggests that over ¾ of the fry were born from just six hen fish! A large, old trout that has been reproducing for many years is (in Darwinian terms) a very fit fish and well adapted to its environment. 

Large fish are more susceptible to physiological stress when caught – they fight harder and for longer, and people tend to take longer to release them whilst they get that ​‘trophy’ photo. Large fish also suffer more during warmer temperatures than smaller individuals because of their gill area to body volume ratio.

Given the contribution that large fish make to the overall health of the population, it makes sense to follow the guidance above and release them to breed and perhaps be caught by another lucky (or highly skilled) angler. 

Catch and release and angling pressure 

It would be wrong to suggest that all trout that are released, even those caught and released properly based on these guidelines, will survive and breed. Some highly skilled anglers report catching 20 or 30 fish in one day – all safely and no doubt expertly released, of course. But this level of angling pressure – whether from one person or many – will have an impact and we should bear this in mind and think about exercising some restraint and be mindful of the environmental conditions. For example, avoiding fishing when water temperatures are high. 

More information

The Keep ​‘Em Wet website is a very good source of information about catch and release for all fish species. 

There are a large number of academic articles that result from research about various aspects of catch and release for salmonids and other fish species. The guidance on this webpage is based on the conclusions that consistently appear in that research (much of which has also been helpfully listed by Trout Unlimited’s Brian Hodges in this annotated bibliography). 

If you would like more information please contact our Research and Conservation Officer (North), Professor Jonathan Grey.