Fish Handling Techniques

Recreational fishers can play their part by only taking the fish that they absolutely need for a feed. Fish above the minimum legal size should be kept and undersized fish should be returned carefully.   

Most recreational fishers understand the rules and, overall, compliance figures are high, so what else can recreational fishers do to help maintain healthy fish stocks?

There are a vast array of hook types and sizes available in New Zealand, and it can be confusing trying to figure out what to buy. MPI recommends: 

• Using big hooks to reduce the chance of an undersized fish managing to get its mouth around the hook. Even though a gut- or gill-hooked fish might appear healthy and swim away, the internal damage it causes increases the chance the fish will die later. 

• Use barbless circle hooks to significantly reduce gut hooking and make releasing unwanted fish in the water much easier.

• If you keep catching undersized fish, it’s best to move to another spot.

There are no restrictions on what fish recreational fishers can legally return to the sea.

In the SNA 1 fishery, recreational fishers return one fish for every one they keep. That means that for someone keeping their bag limit of seven snapper in SNA 1, they are probably really catching fourteen fish and returning seven.  

The problem with returning fish is that not all fish released alive go on to survive. As fish are reeled in, the rapid decrease in pressure causes gas to expand inside their bodies. This is why some fishes’ eyes are popping out or their stomach has expanded to protrude from their mouth when landed. The technical term for this is barotrauma.      

In one study from Australia, 100% of fish hauled up from 20m showed some sign of barotrauma. Of these fish, 75% showed the following three signs at the same time: the stomach expanding into the mouth, swelling around the anal cavity due to internal bloating, and the colon extending out past the anal cavity. Fortunately, signs of barotrauma don’t always mean a fish will die. 

Based on the 2011-2012 national panel survey and estimated mortality figures, recreational fishers kill between 300,000 and 900,000 snapper in SNA1 through returning fish. This is in addition to the fish that they take home.

Of the fish that are released and survive, there may be damage to their ability to breed for the next season at least. This is especially the case with fish caught and released during the spawning season, with their enlarged gonads allowing less space for the swim bladder to expand as they are reeled up from depth.  

Snapper released after being caught in deep water have a much higher chance of dying than those caught in shallow water. Research shows that more than half of all snapper caught and released in water deeper than 45 metres will die.

We understand that photographing big fish to share with friends and family is a big part of recreational fishing. Many fishers then go on to release these fish with the idea that they will continue to live and breed another day. The science on whether this actually does help our fish stocks is not clear cut.

If releasing fish, be sure to implement the following suggestion measures to increase the chance of them surviving. 

• Make sure your hands are wet – especially if covering the fishes’ eyes, as some anglers do to calm them. Dry hands remove the natural slime and cause burns that can lead to infection and death. 

• Don’t lift the fish by the tail, as this can dislocate the spine.

• Don’t place them on hot boat decks, rocks or sand, as again this will cause potentially fatal burns afterwards. 

• Hold fish with one hand under the jaw and the other behind the anal cavity for quick photos. Fingers inserted inside the gill plate can cause injury. If damaged, or even touched, the fish can struggle to breath afterwards; there is also a high likelihood it will bleed out and die.

• Fish organs are largely unprotected in the gut cavity. Holding fish around the belly can cause internal damage to organs, especially enlarged gonads during the breeding season.

• Make sure that any fish returned are caught in less than 30 metres of water to increase the likelihood of survival afterwards. 

• Return fish as quickly as possible. 

It is well known that seabirds are Nature’s fish finders. Large works-ups can provide great fishing, but they also increase the risk of catching seabirds. Keeping the deck clean and putting bait scraps and fish waste in covered containers provide less of a visual incentive for birds to follow your boat.

Seabirds mostly hunt within six metres of the surface. Sink your bait quickly out of this danger zone. 

Make sure your berley containers are set well below the area where birds can dive. The less fish waste in the water, the less incentive there is for birds to hang around.

Deck hoses and water pistols can be used to scare birds away from bait when setting and retrieving your gear. Aim beside the birds and not directly at them.

Keep in mind that deliberately killing or injuring seabirds is an offence that carries stiff penalties, so instead of taking frustrations out on them, think a little smarter instead – it’s best for all concerned.

If you are catching lots of undersize fish or are being hassled by seabirds it is best just to move on. Birds – especially shags - are likely to catch and eat returned undersize fish, so it’s best to avoid this situation altogether. 

 

Following this advice and keeping up to date with the latest rules and any regulation changes is good for the fish and will help ensure you have an enjoyable and productive summer.

 

Marty Bowers

Senior Fisheries Analyst   

Recreational Fishing Team