Ship strikes threaten fin whales

Aug 17, 2009

By Anuradha Rao

On the morning of Saturday July 25th, a cruise ship entered the Port of Vancouver with a fin whale impaled on its bow. At the time of writing, it is still unclear whether the ship killed the whale or whether it was dead before impact.

Measuring up to 22 metres in length, the fin whale (Balaenoptera physalus) is the world’s second largest living animal, after the blue whale. One of the fin whale’s distinguishing features is a white right lower lip and a dark left lower lip. Fin whales are found worldwide, but especially in polar and temperate waters. They are seen in British Columbia in summer and winter, usually offshore in Hecate Strait and Queen Charlotte Sound.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) lists the Pacific population of fin whales as Threatened. The International Whaling Commission lists them as “Protected” and the World Conservation Union (IUCN) lists them as “Endangered”.

Fin whales tend to be sighted in offshore waters of British Columbia, though populations were significantly reduced by commercial whaling throughout the North Pacific. Whaling removed over 7000 fin whales between 1905 and 1967, and thousands more in the 1970s. Catch rates declined in British Columbia in the 1960s. COSEWIC estimates that today’s population of fin whales is less than half of what it was between 60 and 90 years ago. Along with entanglement in fishing gear, fin whales are also at risk of ship strikes.

An international team of researchers published an article in 2001 in the journal Marine Mammal Science concerning ship collisions with whales. The researchers found evidence of ship collisions with 11 different species of whales around the world, with fin whales hit most frequently. They suggest that an increase in number and speed of ships since the late 19th century may influence the number of whales hit by ships. They say that collisions with ships can result in severed tails, slashes from propellers or internal injuries, and in some cases can lead to strandings.

The researchers also found that vessels of any size can hit whales, but larger vessels and those travelling more than 14 knots are responsible for most serious and lethal injuries. Although whales communicate through sounds, in some cases they appear to be oblivious to the noise of ships, for example when they are engaging in activities at the surface, such as feeding. The confusing sounds of several vessels in an area and other interference with ship sounds may also have an effect on the whales’ behaviour.

Ship strikes are just one of many issues that currently threaten whale populations, but the loss of one or a few individuals can have a significant impact on highly endangered and small populations such as northern right whales, western North Pacific grey whales, and Gulf of St. Lawrence blue whales, according to the researchers. Furthermore, if year-round Arctic sea routes are established, then highly endangered bowhead whales, which currently live away from most shipping traffic, can also be at risk.

Plans to minimize travel in whale hotspots or to reduce speed to less than 14 knots in areas where whales occur may be needed to help reduce this threat. More research is necessary to find out where collisions between ships and whales happen most frequently, and to find ways to prevent these collisions from occurring.

For scientists to learn more about where fin whales may be struck in British Columbia, they need know more about their distribution.  To help, report any sightings of fin whales to the BC Cetacean Sightings Network here or by calling 1866 I SAW ONE.  You can report collisions, entanglements, strandings or other incidents with whales, other marine mammals and sea turtles to the 24 hour, toll-free Marine Mammal Incident Response hotline at  1800 465 4336.

Boaters can help reduce the threat of ship strike for any cetacean by following the ‘Be Whale Wise’ guidelines while on the water.  Learn how to best conduct your boat around whales here.

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Ship strikes threaten fin whales

John Ford

Fin whale struck by a cruise ship in 1999


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