Survival Rates When Releasing Fish

New information on the survival rates of snapper caught and released could help fishers save hundreds of thousands of fish per year and help sustain their fishery, writes Grant Dixon.

A research project commissioned by Fisheries New Zealand and undertaken by the National Institute of Water and Atmospheric Research (NIWA) in collaboration with Ngāti Kuta, Legasea, and Bluewater Marine Research, confirmed what many recreational fishers already knew about safe handling practices. It looked at survival rates of recreationally caught and released snapper, showing that around 85% of the fish were still alive at the end of the first experiment. The fieldwork took place in April and November 2022, with fish caught from depths of 5-35m and monitored in holding pens for three days.

Bruce Hartill, the principal scientist for Fisheries New Zealand, led the project in his former role at NIWA. He says that although the numbers can vary year-to-year, recreational fishers land over 4,000 tonnes of snapper annually in New Zealand.

“For every snapper landed, there will be approximately five times that number under the minimum legal size that will be returned. What happens to those fish can have a real bearing on sustainability.”

Sam Connelly releases a snapper taken from Great Barrier during an early morning soft-baiting mission in the shallows. 

The research took place in Mangahawea Bay, off Moturua Island in the Bay of Islands, with volunteers fishing from a charter boat. Researchers recorded details of each captured snapper, including how the fish was hooked and the depth it was caught. The fish were quickly transferred to one of nine holding nets in 15m of water and monitored over the following five days.

“Two major impacts on fish survival rates were the depth snapper were caught and where they were hooked. But there are some things we can do to help,” Bruce Hartill says.

“Using recurve hooks which are less likely to be swallowed by the fish, handling them carefully while making sure not to touch the eyes or the gills, and releasing them quickly will give them the best chance of survival. Mortality rates were also about five times higher for the snapper caught in depths greater than 25m than if they were taken from under 10m.

“If the fish was caught in deeper water, release weights will help get them back to their capture depth before they are free to swim away.

Going down. Hamish Beesley’s snapper heads back to the reef after successfully being released.

“Anyone that goes fishing wants the same thing – both a feed for today and healthy fish in the water for tomorrow, so handling practices and the gear used can make a real difference.”

Final survey results are expected to be available by the middle of 2023. The results will give anglers a better understanding of the consequences of throwing fish back, so there’s less unseen mortality, and help fisheries managers set optimal fishing regulations, such as daily bag and minimum size limits.

LegaSea and the likes of recreational fishing personalities Matt Watson and Tony Orton, along with NZ Fishing News and www.fishing.net.nz, have long been advocates of fish care, promoting safe release and fishing practices. In particular, writers Mark Kitteridge and Sam Mossman have driven this education process. The NZ Sport Fishing Council’s public advocacy arm – LegaSea – has produced the comprehensive Fish Care document and video on the subject.

The late Paul Barnes, a passionate recreational fishing advocate, developed the popular Target recurve hooks that incorporated a short length of wire attached to the shank sticking out at 45 degrees just beneath the eye, discouraging small fish from swallowing it. 

Measure-based contests encourage release

Knowing how and when to release fish is more important than ever, given the proliferation of catch, measure and release tournaments where anglers now compete in centimetres instead of kilograms.

The measure-based events allow anglers to release big fish and still be eligible for honours, whereas, in weight-based events, all fish had to die to feature in the results.

NZ Fishing Media has been hosting the Export Fishing Contest for the last 10 years, where anglers throughout NZ can fish for nine target species and compete for bragging rights along with some fantastic prizes over a 12-month season.

NZ Fishing Media Managing Director Grant Blair, who initiated the event, notes that anglers had recorded the release of 1226 snapper with an average length of 60.5cm and 452 kingfish averaging 100.5cm since the competition started in 2014. Large numbers of other species have also been released and based on average weight tables, he estimates well over 10 tonnes of competition fish have lived to see another day.

The advent of major measure-based events makes it more critical than ever that anglers are up to speed with safe handling practices.

Thanks to Export, the event is free to enter, and last year one lucky angler entered just one fish, and his name was drawn to win an Extreme centre console boat worth $80,000. A similar Extreme boat prize is up for grabs in the 2022-23 competition year.

“There is no compulsion to release the fish once it has been measured but we’re empowering anglers to make the best decision for the catch at the time,” Grant says.

NZ Fishing Media has developed an online platform which makes it easy for clubs and other organisations to run measure-based contests. All anglers need is a smartphone and an approved measure to participate.

Florida Proposes Mandatory Venting Tool Use

In the current issue of the American Sportfishing magazine, a news item by Bob McNally highlights a proposal from the Fish and Wildlife Conservation Commission (FWC) to help increase the survival of released reef fish.

The rule, if passed, will require all boats to carry specialised descending devices or venting tools on board and ready for use when targeting reef fish in state waters. Survival of released deep reef fish is a state and federal management priority in South Atlantic and Gulf of Mexico waters, where red snapper is a popular target species.

According to the FWC, the proposed rule would require using a descending device or venting tool to release any fish showing signs of barotrauma. When reef fish (snapper, grouper, etc.) are hooked in deep water, they can suffer pressure-related injuries known as barotrauma, also called the ‘bends’ by SCUBA divers.

Such injuries in fish include a stomach protruding out of its mouth, bulging eyes, bloated belly, distended intestines, and inability to swim back down to a deep reef. If not appropriately treated, barotrauma can be deadly to reef fish.

Two descending devices recommended by the American fisheries managers – the Shelton (right) and the Seaquililizer. 

When used correctly by anglers, specialised descending devices and venting tools help released fish avoid barotrauma and survive to get back to their deep reef homes.

The FWC explains that descending devices are weighted gadgets capable of releasing fish at a sufficient depth to recompress expanded gas and help fish recover from the effects of barotrauma.

Venting tools are sharp, hollow instruments that allow expanded gas to escape from an over-expanded swim bladder, allowing fish to survive the bends.

Barotrauma mitigation tool requirements have already been adopted in Gulf and Atlantic federal waters. In Gulf federal waters, anglers may use either a descending device or a venting tool that is rigged and ready for use. In Atlantic federal waters, fishermen are required to have a descending device that is readily available.

NZ’s Matt Watson (ITM Fishing Show) has been a strong proponent of venting tools for many years and has demonstrated on several occasions just how to do this. NZ Fishing News has also previosuly run numerous articles discussing barotrauma and release techniques, including how to make a simple but effective release device.

Matt Watson uses a venting tool to give this snapper a chance of survival despite being caught in 55m of water.

Release Tips

• Use a scale-friendly rubber net

• Keep fish intended for release in the net and the water while removing the hook

• If measuring fish, do so quickly; get your photos and put them back asap

• If you bring a fish you intend to release aboard, lay it on the wet towel while you remove the hooks

• Don’t touch the fish with bare, dry hands

• To subdue a fish while removing the hook, place a wet towel over its head

• Don’t lay a fish on a hot deck, sand or rocks

• Try to release big fish in the water and avoid dragging them over the gunwale or rocks

• Keep hands away from gill areas. Handle kingfish by gripping them in the mouth with a gloved hand or a lip gaff

• Time is of the essence

• Fish with non-offset circle hooks for easier release

• Crush the barbs down on your hooks, especially trebles, to make releasing fish easier

February 2023 - Grant Dixon
New Zealand Fishing News Magazine.
Copyright: NZ Fishing Media Ltd.
Re-publishing elsewhere is prohibited