Question of the month

During an interview with Moira Brown, Whales on-line asked him the following question :

Why are right whales so susceptible to ship strikes and entanglement in fishing gear?

M. B. :

With a population of approximately 325, the North Atlantic right whale is considered to be one of the most threatened great whales in the world. The right whale got its name from whalers who considered it to be the right whale to hunt due to its coastal habits, the fact that it is a slow swimmer (easier to catch) and because it floats when killed. Decimated by whaling, it has been protected internationally since 1935. However, the North Atlantic right whale population is still threatened by human activity. The same characteristics that made it the right whale to hunt render it vulnerable in our modern world. Its coastal habits and slow pace make it susceptible to entanglement in fishing gear and to ship strikes.

Right whale feeding, mating and calving grounds are generally found in coastal areas where shipping traffic is intense. Such is the case in the Bay of Fundy and Roseway Basin (south of Nova Scotia) in Canadian waters and Cape Cod Bay, the Great South Channel (east of Cape Cod), the Gulf of Maine, as well as in the only known calving ground off Georgia and off Florida in U.S. waters. The fact that ships are increasing in size and speed and that right whales are large, slow cetaceans that feed, socialize and rest at the surface means that they are prone to being struck by ships where there is an overlap between right whales and shipping. It has also been noted that even if they hear the ships approaching, right whales often appear to ignore their presence, although they have been seen, on occasion, to swim away from some vessels at the last moment. It is possible that they become accustomed to the noise and no longer pay any attention to it, concentrating instead on feeding or other group activities. Furthermore, right whale cows accompanied by calves often tend to spend more time at the surface, increasing the risk of ship strikes. Almost half of the known mortalities of right whales over the past decade have been attributed to ship strikes.

Entanglement in fishing gear is another serious problem. Present-day fishing gear uses wear-resistant plastic ropes that are more apt to fatally entangle a whale. Approximately 70 percent of the North Atlantic right whale population bears scars caused by fishing gear and there have been at least eight known mortalities from fishing gear entanglement. This number is likely lower than the actual number of entanglement mortalities because entangled whales often have difficulty feeding and become emaciated over several months and sink after death. Right whale sighting data from the New England Aquarium, combined with information from the fishing industry, can be used to determine where, when and what type of fishery poses the greatest threat to these whales. Results will be used to develop actions to minimize whale entanglement, as well as minimizing damage to local fisheries.

Portrait of Moira Brown