Safe Release of Atlantic Halibut
Recent research has established that 50 percent of female Atlantic halibut (Hippoglossus hippoglossus) in the Gulf of St. Lawrence (NAFO Division 4RST) reach reproductive maturity at a size of 130 cm. This finding has raised concerns that large numbers of females could be captured before being able to spawn. It is important, therefore, to minimize the mortality of Atlantic halibut smaller than the legal minimum size. Current licensing conditions prohibit the retention of Atlantic halibut that are less than the minimum size specified in license conditions. If such fish are alive they must be released in a manner that causes the least possible harm.
A key to developing and protecting the spawning potential of Atlantic halibut in the Gulf of St. Lawrence is to ensure that undersized halibut captured in directed fisheries, as well as all halibut captured as a by-catch in fisheries where halibut retention is prohibited, are released back into the water with the least possible harm.
Surveys and experiments conducted with Atlantic halibut and the closely related Pacific halibut (Hippoglossus stenolepis) indicate that there are two factors that have a marked effect on the survivability of the species:
- time on deck before release; and
- the extent of injuries sustained by the fish while captive.
Therefore, to maximize the chance of survival, fish harvesters must:
- minimize the time that the halibut spends out of the water before release (five minutes should be the maximum handling time); and
- release the fish from the fishing gear in such a way that further injury is avoided. Do not use a gaff on any fish that appears undersized.
Ensuring the proper release of the species is a key element of good fishing practices, fishing ethics and a proper code of conduct. This will go a long way to help continue building the stock of Atlantic halibut in the Gulf of St. Lawrence.
Release from Hook and Line Fishing Gear
Fish harvesters should use circle hooks in all fishing situations when directing for Atlantic halibut as they tend to catch the fish in the corner of the jaw and minimize the chance of them swallowing the hook. Methods of release include:
Cutting the gangion
This is the preferred method to release Atlantic halibut from hook and line fishing gear. To do so, cut the gangion close to the hook if possible and release the fish with the hook still embedded. The hook will fall out by itself in one or two days.
Use the gaff to hold the hook against the roller until the hook is straightened and pulls out of the fish. The hook can also be cut using heavy duty pliers or bolt cutters.
Slide the curved end of the gaff hook down the gangion to the hook, engaging the shank of the hook on the shaft of the gaff. Maintain tension on the gangion, lift the end of the gaff and twist it, rolling the hook so that the fish is hanging down on the point of the hook, the hook being supported above the location where the fish is pierced. Gently shake the gaff to make the fish fall off the hook.
Avoid the use of hook strippers or any method that pulls the hook through the jaw.
Release techniques courtesy of Steve Kaimmer, International Pacific Halibut Commission
Release from Gillnets
If the fish is still alive release it from the net as soon as possible, taking care to avoid injury to the operculum or the gills. If necessary, cut away the net strands to release the fish.
Increasing the survival rate of Atlantic halibut so more of them grow to reproductive size is essential to the development of these valuable fish as a sustainable source of seafood. Take the time to learn the best methods for releasing non-target halibut (undersize and by-catch) and apply them to your fishing activities.
For further information, please contact your nearest DFO office or visit the Fisheries and Oceans Canada website.
© Her Majesty the Queen in Right of Canada, 2009
Catalogue No.: Fs114-16/2009E
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