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The Catch: waste not, want not

Oct 24, 2017 Environment ,Fishing ,General Interest

One of the results of the change to the minimum size limit for snapper from 27cm to 30cm in Snapper 1, instituted in 2014, has been an increase in the number of small snapper released back into the water to comply with the law. The onus, therefore, is on us as anglers to ensure the fish we’re obliged to discard survive, writes John Eichelsheim.

Unfortunately, while I would hope most fishers obey the law and release undersized fish, from my experience many of them release fish in such poor condition they are unlikely to survive. These fish are wasted – lost to the system.

Out of ignorance, or sometimes pure frustration, undersized fish – and non-target species too – are often roughly handled, or kept out of the water for too long. Many don’t survive the experience, dying immediately or hours, days and weeks later.

The problem is worse when fishing in deeper water, and not only for undersized fish. I’ve written about this before, but it’s becoming increasingly clear that snapper (and many other species) pulled to the surface from deep water suffer the ill effects of decompression. The associated physiological damage, called barotrauma, includes distended swim bladders that can push the stomach out through the mouth, ruptured swim bladders and damage to the fish’s internal organs. In severe cases, the eyes bulge and gas escapes through the skin, lifting the scales. The post-release survival of any fish suffering this degree of barotrauma is unlikely.

Unhook in water 2_cmyk (Small)

From what I’ve seen, if you fish for snapper or any other species susceptible to barotrauma in 20-30 metres of water or deeper, catch and release might not be a viable option – work-up fishers take note!

Venting fish usually allows them to swim back to the bottom after release, but one commercial fisher I talked to reckons most of these fish die, based on his experience with the live fish export trade to Japan a few years back.

To ensure they would arrive in good health, live fish were kept in holding tanks for three days before being air-freighted to Japan. The majority of those fish taken from deeper than 20 metres, most of which had been vented using a hypodermic needle, died in the tanks, he said.

However, there is evidence from several scientific studies, including work in Australia examining snapper, that fish survive barotrauma after venting. According to various studies, the most important thing seems to be to get fish back into the water fast and down to a depth of at least 10 metres, something my commercial fisher with his holding tanks was not able to do. See Barotrauma below.

BEST PRACTICE?

Whenever catches of undersized fish becomes a problem and/or catch and release is not feasible, or at least not ethical because fish are going to die anyway, anglers should take action. Stop fishing immediately or move somewhere else, preferably to shallower water.

If fish are of legal size but release is not a good option, stop fishing as soon as the legal bag limit is reached or you have enough fish for your needs: no high-grading or catch and release fishing.

For the well-being of the fishery, some people would argue that anglers are better to keep every fish they catch, regardless of
size or species, until they reach the daily bag limit and then stop fishing. In some parts of the world, such limits already exist.

In the USA and Canada there are even stricter restrictions, including season limits for certain fisheries i.e three salmon per
angler per season and no high-grading.

CATCH AND RELEASE

As someone who fishes regularly for recreation, I practice catch and release all the time, releasing both undersized fish
and fish I don’t need for the table. I seldom keep my limit and I might release dozens of fish in a day when the fishing
is good, so I need to be happy those fish are going to survive. However, when I fish deep water, I keep what I catch and stop when I’ve caught enough.

Since most of my fishing is done with lures in less than 20 metres of water, barotrauma is seldom an issue for the snapper, kingfish, kahawai and trevally I routinely catch. I’m well-practiced at handling and releasing fish at the boat, so I’m confident they live to fight another day.

Handling fish sympathetically is important, including small fish, which anglers often treat too casually. Where possible, don’t handle fish at all other than to remove the hook (use pliers to squeeze down the barb and make hook removal easier). Bigger fish can be unhooked in the water beside the boat, in the net (you can leave the net in the water), or inside the boat on the floor.

quick photo_cmyk (Small)

If you must bring fish aboard, don’t place them on a hot and/or dry surface (deck or gunwale). Consider lying them on
a freshly-wetted towel. I usually unhook bigger fish in the net because the net bag gives some protection against contact with
the deck, which can damage the mucus layer on the skin.

With small or undersize fish, handling is almost unavoidable, so always wet your hands first, don’t squeeze the fish, especially around the gut area, and keep your fingers away from the eyes and gills. Cut the trace on deeply hooked fish, don’t try removing the hook.

Return fish to the water as quickly as possible – if you want a photo, make it quick and use wet hands to hold the fish. Slip
small fish back into the water in the same way as you would larger fish – don’t toss them high into the air so they impact the
water with force. Be prepared to ‘spear’ large fish into the tide to give them a head start on their dive for the bottom and when fish are obviously exhausted, cradle them gently in the water (or in the net) until they are ready to swim away.

If a fish is unable to swim away, or continually pops back to the surface, you can try venting it (see barotrauma below) – or you can add it to your bag.

ATTITUDES TOWARDS UNDERSIZED FISH

Take a stroll along any wharf or easily-accessible stretch of rocky shoreline around Auckland, and probably in other centres too, and you will find people fishing.

Around the Waitemata at least, the majority are recent arrivals to this country, who bring their own cultural experiences to fishing. Many use fishing techniques that specifically target small fish, valued as food, regardless of the species, while some take large numbers of fish, shellfish and crustaceans when they are available, showing scant concern for the impact of such fishing practices.

gathering shellfish_cmyk (Small)

It’s very easy for someone fishing this way to fall foul of our fisheries law, since the fish they catch are often juveniles of species which have a minimum size limit. Many undoubtedly keen newbie fishers seem ignorant of the laws governing recreational fishing, put in place to ensure a sustainable fishery for all New Zealanders. Some simply ignore them…

I have witnessed people keeping undersized specimens of all sorts of fish, including snapper. The catches can be excessive too – I watched one very busy gentleman, who was fishing from a local breakwater with four rods at once, drop a procession of small kahawai into his bucket, most well under 25cm. There is no size limit on kahawai, but the recreational bag limit is 20 and they are part of a combined (multispecies) daily bag limit of 25 fish. He didn’t stop at 20 fish or 25 either…

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Not all fish species have a minimum size limit, nor a limit to the number you may take, but most of the popular recreational species do, and quite a few others as well. Size and bag limits vary by geographical region, so anglers need to check the regulations current in their fishing area.

In my opinion, many more fish species should fall under the umbrella limit of 25 fish per person per day, or some other limit. Open-ended bag limits for any fish, shellfish or crustacean species are outmoded and unsustainable. Indeed, I feel wild food gathering of any sort needs to be strictly controlled given our fast-growing, largely urban population.

Copies of the fishing regulations are available online from Ministry of Primary Industries website www.mpi.govt.nz/travel-and-recreation/fishing/fishing-rules/ in Chinese, Korean, Tagalog (Filipino), Samoan and Tongan as well as English and Maori.

Many popular fishing spots have daily catch limits clearly signposted in multiple languages, so ignorance of the rules is a poor excuse.

SUSCEPTIBLE TO BAROTRAUMA

To varying degrees, most bottom-dwelling and midwater (demersal) species with swim bladders. Although the majority
can make vertical movements between deep water and shallow, the movement must be slow enough for them to adjust the volume of gas in their swim bladders. Many bony fish use swim bladders to control buoyancy; rapid decompression releases so much gas from the bloodstream and tissues all at once, it overwhelms the swim bladder’s ability to compensate for depth changes.

Susceptible species include most of the commonly-caught bottom and midwater species: snapper, blue cod, tarakihi, hapuku, bass (but not bluenose), red cod, various wrasses, pigfish, maomao, banded perch and most reef-dwelling fish.

LESS SUSCEPTIBLE TO BAROTRAUMA

Most pelagic species, plus mid-water and bottom-dwelling species that transition between deep-water zones and the
surface (often at night), sharks and bottom-dwelling bony fish without swim bladders (flat fish) or with wax-filled swim
bladders (orange roughy). Examples: tunas, marlins, swordfish, oilfish, escolar, kingfish, jack mackerel, slimy mackerel, barracouta, various sharks, flounder, turbot and sole.

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TO VENT OR NOT?

Studies in Australia have indicated good survival rates for snapper taken in 37-50 metres of water and then released after
‘venting’ – perforating the swim bladder, either through the everted stomach in the mouth, or through the side of the fish
using a hypodermic needle.

Survival rates were 90 percent at 37-50 metres, 86 percent at 51-100 metres and 85 percent at 101-180 metres – surprisingly high and better for fish vented through the mouth.

The researchers also recorded the perforations in swim bladders and stomachs of the fish they sampled healed rapidly: 64 percent of stomachs and 45-55 percent of swim bladders had healed within three days of capture.

Other studies have shown that the use of circle hooks, minimising the surface interval and rapidly recompressing the
fish to at least 10 metres are the keys to maximising survival of fish taken from depth. Once fish get down to around 10 metresor so, they can usually look after themselves. Venting allows them to quickly dive to this depth and deeper.

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