Baleines noires et attirail de pêche

Les baleines noires furent chassées pour leur lard et leurs fanons à un point tel qu'elles sont presque disparues. En 1937, elles furent protégées contre la pêche commerciale, mais la population ne s'en est pas remise dans le Nord de l'Atlantique; seulement de 300 à 350 baleines ont été identifiées jusqu’ici. 

Les facteurs limitant le retour des baleines comprennent les collisions avec les navires, l'enchevêtrement avec les attirails de pêche, la variance génétique limitée et la dégradation de l'habitat. Bien que les collisions avec les navires soient un danger majeur pour les baleines noires, l'enchevêtrement avec les attirails de pêche s'avère être un autre danger important.

Présentement, le désenchevêtrement des baleines noires est la méthode la plus efficace pour débarrasser les baleines de ces attirails de pêche. Le désenche-
vêtrement des baleines est dangereux, difficile et souvent loin des côtes; et finalement, les tentatives ne sont pas toujours  fructueuses.

Il est donc essentiel d'éduquer les pêcheurs concernant les façons qu'ils peuvent réduire la fréquence des interactions entre les baleines et les attirails de pêche. La coopération de l'industrie de la pêche est capitale afin de réellement résoudre le problème de l'enchevêtrement.

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Right Whales & Fishing Gear

Laurie Murison
Grand Manan Whale & Research Station
Oct 23, 2002

ight whales were hunted to near extinction for their blubber and baleen plates (IWC 1986). They were protected from commercial whaling beginning in 1937 but despite this, their population has not recovered in the North Atlantic, with only 300-350 whales identified. The Canadian North Atlantic Right Whale Recovery Plan (RWRT, 2000) lists factors limiting the recovery of North Atlantic right whales, including ship strikes, entanglement in fishing gear, low genetic variability and habitat degradation.

While ship strikes are a major, usually fatal, hazard for right whales, entanglement in fishing gear is emerging as another major threat, although as early as 1909, a young right whale was entangled in a "fish trap" in Provincetown Harbor, MA, and subsequently killed with a bomb lance by the local fishermen (Allen, 1916).

Entrapment in fishing gear such as herring weirs, an ingenious large trap designed to intercept herring at night when the fish are close to shore, is a small problem. Entrapment differs from entanglement in that the whales are free swimming within the trap, and are not tangled in any of the gear. Five right whales have been entrapped in herring weirs in the Bay of Fundy (a mother and calf in 1976, a single animal in 1996, and a pair of females in 1998). The two pairs of animals successfully swam out with the assistance of the weir operators. The single whale apparently got out on its own.

Fixed fishing gear, often set on the bottom with lines and floats to the surface (for example, lobster and crab traps, gill nets, longlines), is the most likely source of many of the entanglements. Only a few right whales have been seen being entangled in fishing gear; however, a majority of the North Atlantic population exhibits scarring consistent with previous entanglements (Kraus, 1990). Although entanglement usually does not lead to death, it may cause secondary problems, such as infection or inability to feed, making them vulnerable to further entanglements because of trailing gear or exhaustion. The latter may result in a right whale spending more time at the surface and therefore it would be more vulnerable to ship strikes. Young right whales are particularly at risk because of their fast rate of growth; lines can become embedded quickly, leading to constriction and infection. Other large whales such as humpbacks are also vulnerable to entanglement in fishing gear. The Center for Coastal Studies in Provincetown, MA, maintains a website and database of large whale entanglements along the eastern seaboard.

Right whales are particularly vulnerable to entanglement in fixed gear because they are slow swimming and feed by skimming - opening their mouths and filter feeding for up to 20 minutes at a time. Lines are easily trapped in their baleen. Their forward vision is also limited and they may not see obstacles immediately in front of them. Right whales are also known to be curious about objects but when startled will attempt to flee. They also tend to roll when they become entangled, making things worse. Their powerful bodies are able to free themselves of most of the gear but rope and sometimes floats remain, tangled through the baleen, wrapped around flippers, around the body and the tail stock.

At present, disentanglement of right whales is the most effective method to rid right whales of gear. Disentangling whales is dangerous, difficult and often far from shore. Not all attempts are successful and repeated attempts are often necessary. Protocols for disentangling large whales have been developed, primarily by the Center for Coastal Studies in Massachusetts and by Dr. Jon Lien, of St. John's, Newfoundland. Caches of equipment are located along the eastern seaboard, including in the Bay of Fundy. There are first responder kits on Grand Manan and Campobello Islands, NB, and full caches of equipment on Brier Island, NS and Lubec, ME (seasonal). The equipment used to disentangle whales is constantly augmented to better suit new situations but cutters, grapples, poles and floats are standard equipment.

Despite heroic efforts to disentangle right whales, even whales that are successfully disentangled are not free from secondary infection from deep cuts. A young female right whale disentangled in the Bay of Fundy in August 2002, washed up dead on Nantucket Island, MA in October 2002. Although cause of death was not determined, a deep infected gash was present. In 2001, the right whale named Churchill garnered public interest because of the numerous disentanglement attempts, including using sedation. Satellite tracking enabled researchers to follow the whale and attempt were made to disentangle the whale when he was close enough to shore. Without satellite tracking it is difficult to relocate an entangled whale, unless the reporting vessel is able to standby until disentanglement teams arrive. Even then, weather, lack of daylight, complicated entanglements and uncooperative whales may not allow the whale to be disentangled on the first try. Satellite tracking reduces the effort spent relocating the whale. The satellite telemetry buoy is usually attached to a line trailing from the whale.

In Canada and the U.S., several committees and research efforts have been devoted to mitigating the problem. Attempts are made to identify the fishing gear types in which right whales become entangled with the intent of possibly modifying the gear to prevent or reduce the severity of the entanglement. The problem of entanglement may also be addressed by seasonal area closures, as was seen in June and early July off Cape Cod in 2002. Right whales stayed in an area where they could become entangled in fishing gear and the National Marine Fisheries Service requested fishing gear be removed from the area until the whales departed. Any expansion of fishing effort or development of new fishing methods should seriously consider the potential impact on right whales. Educating fishermen about ways they can reduce the frequency of interactions between whales and fishing gear is also essential. The cooperation of the fishing industry is essential to fully address the entanglement problem.

References:

Allen, G. M. 1916. The whalebone whales of New England. Mem. Boston Society of Natural History 8(2): 322pp.

IWC, 1986. Report of the workshop on the status of right whales. Report of the International Whaling Commission (Special Issue 10): 1-33.

Kraus, S.D. 1990. Rates and potential cause of mortality in North Atlantic right whales (Eubalaena glacialis). Marine Mammal Science 6:278-291.

Right Whale Recovery Team (RWRT), 2000. Canadian North Atlantic Right Whale Recovery Plan. Report supported by World Wildlife Fund Canada and the Department of Fisheries and Oceans, September 2000. 90pp.