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More Undersize Catches Can Survive With "Venting" Method

Date:
February 26, 1999
Source:
University Of Florida, Institute Of Food And Agricultural Sciences
Summary:
Imagine you're the captain of a charter vessel taking a bunch of anglers to sea for a day of fishing. They catch a beautiful grouper, but it's a few inches undersize, so you have to take the fish off the line and throw it back. Now imagine that the fish floats away on the waves, unable to descend to its normal depth, and is snapped up by a bird looking for dinner. That's the scenario the University of Florida and the Florida Sea Grant College program are trying to prevent.

SARASOTA---Imagine you're the captain of a charter vessel taking a bunch ofanglers to sea for a day of fishing. They catch a beautiful grouper, butit's a few inches undersize, so you have to take the fish off the line andthrow it back.

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After all, it's the law.

Now imagine that the fish floats away on the waves, unable to descend toits normal depth, and is snapped up by a bird looking for dinner.

The fishermen are irritated, you've lost any word-of-mouth business andfisheries laws look pretty silly.

That's the scenario the University of Florida and the Florida Sea GrantCollege program are trying to prevent. Frank Lawlor and John Stevely,marine extension agents for Sea Grant and UF's Institute of Food andAgricultural Sciences, are teaching charter captains and fishermen atechnique to help undersize reef fish survive after they are tossed backinto the water.

The problem is with the creature's swim bladder, an organ the fish uses toregulate its buoyancy, Stevely says. When a reef fish like snapper orgrouper is hooked in deep water and reeled to the surface quickly, its swimbladder does not have time to adjust to the change in water pressure. Theswim bladder ruptures and swim bladder gas fills the gut cavity. Anundersize fish with air in its gut cavity has no chance for survival whentossed back into the sea because it can't descend or right itself to swim.

"An 18-inch grouper is a beautiful fish," says Stevely. "It could be thelargest fish someone has ever caught, and then if the captain throws itback and the fish floats away on the surface of the water it reallyirritates them.

"Sea Grant got involved when charter captains asked for help. They werereturning more undersize fish to the water, but many clients weredistressed about throwing back fish that looked like they were going to dieanyway," Stevely said. "Coming up with a means of increasing survival ofthe released fish was important, because if the fish returned to the waterdon't survive, then fisheries management laws will not be very effective."

Frustrated charter captains had been trying to deflate fish, but were usingtechniques that injured the fish further. Some fishermen were jabbing thefish with a knife or ice pick and cutting internal organs. Others were justsqueezing the fish until the gut cavity popped.

Sea Grant stepped in and designed a venting method that deflates the gutcavity and gives fish the best chance for survival. A tool made of a hollowsteel cylinder is inserted underneath a scale behind the base of thepectoral fin to release trapped air. The tools that will work include asharpened sports ball inflating pin or a veterinarian's cannula. The pointis that it is hollow and allows gas to escape.

"By giving the fishermen a means of venting, we're promoting voluntarycompliance with fisheries laws," Stevely said. "It's important to returnthe smaller catches so the fish have a chance to grow, reproduce, replenishthe stock and perhaps be caught another day, when they are bigger."

The small puncture wound inflicted by the venting tool has a good chance toheal because the cut is small and covered by muscle and scales. The swimbladder itself heals in about four days. And fish that are vented at leasthave a chance for survival, unlike a fish with an inflated gut cavity.

Mote Marine Laboratory in Sarasota has collaborated with Sea Grant onevaluating venting methods, and Karen Burns, Mote fisheries biology programmanager, said venting increases the survival of undersize catches that arethrown back.

"If the minimum size regulation is to work, then we need to make sure thatundersize fish that are thrown back survive," Burns said. "This is an easy,shipboard method to enhance the survival of undersize fish."

Fishermen don't mind following laws that force them to throw back undersizereef fish, Stevely said. They just get frustrated throwing back a fish thatis going to die anyway. Most fishermen are conservation-minded andunderstand that the minimum-size laws are designed to allow fish to spawn,replenishing populations and making for good fishing for generations tocome.

"Venting is an important part of the fisheries management process," Stevelysaid. "We can put down rules about returning undersize catches to thewater, but we need to take the next step and try to ensure that theysurvive. It's a great stride forward, and that's why this work is soimportant."


Story Source:

The above story is based on materials provided by University Of Florida, Institute Of Food And Agricultural Sciences. Note: Materials may be edited for content and length.


Cite This Page:

University Of Florida, Institute Of Food And Agricultural Sciences. "More Undersize Catches Can Survive With "Venting" Method." ScienceDaily. ScienceDaily, 26 February 1999. <www.sciencedaily.com/releases/1999/02/990226075210.htm>.
University Of Florida, Institute Of Food And Agricultural Sciences. (1999, February 26). More Undersize Catches Can Survive With "Venting" Method. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/1999/02/990226075210.htm
University Of Florida, Institute Of Food And Agricultural Sciences. "More Undersize Catches Can Survive With "Venting" Method." ScienceDaily. www.sciencedaily.com/releases/1999/02/990226075210.htm (accessed December 20, 2014).

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