The fin whale

Limiting factors

While present-day and pre-whaling North Atlantic fin whale population estimates remain imprecise, there is no doubt that numbers fell considerably due to commercial whaling activities. Currently, several man-made threats could prejudice the recovery of this population.*

* From COSEWIC 2005. COSEWIC assessment and update status report on the fin whale Balaenoptera physalus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. ix + 37 pp. and Species at Risk Act - Legal Listing Consultation Workbook, Fin whale (Atlantic Population), November 2005. Fisheries and Oceans Canada, 19 p.

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Accidental entanglement in fishing gear

Since large-scale commercial whaling has been banned, entanglement in fishing gear has become, without a doubt, the greatest threat to baleen whales. Yet, it is difficult to evaluate the extent of the problem as many cases involving fishing gear go unnoticed or are never reported. The recent introduction of sunken gillnets in the Bay of Fundy may represent a threat to fin whales. Lobster fishing gear near the Nova Scotian Shelf trapped seven fin whales in 2003. Numerous cases of fishing gear tangled around the tails of various baleen whale species have been reported and it seems that fin whales are among the species that fall victims to this type of activity.

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Ship strikes

Most ship strikesoccur with ships less than 80 m in length moving at speeds of 14 nautical miles per hour or more. Ship strikes are probably not all reported; mortally wounded animals occasionally sink without ever being seen. Some researchers believe that in areas where shipping traffic is intense, animals become accustomed to the ambient noise created by ships and are less likely to avoid them. Therefore, any increase in ship sizes or numbers constitutes an added threat to fin whales. Two areas are of special concern: the St. Lawrence— commercial shipping gateway to eastern North America—and the waters around the port of Halifax.

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Noise pollution and other man-made disturbances

Noise pollution has intensified significantly in the marine environment since the 1950s. The St. Lawrence and Atlantic Canada are no exception. This could have serious consequences for Atlantic fin whales. Sounds caused by commercial shipping, explosions associated with seismic exploration and all other low-frequency sounds could very likely lead to physical and behavioural modifications, injury and even death. The distance between sound source and animal, the transmission frequency, intensity and duration, the repetition of noisy occurrences, the auditory capacity and degree of habituation of the animal are all interdependent factors that determine the extent of the impact.

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Whaling

Although halted in Canada, whaling remains a threat for fin whale populations. This species is in fact still hunted in Greenland where natives are authorized by the International Whaling Commission to carry out subsistence whaling. Furthermore, Iceland has stated that it is interested in the possibility of resuming the fin whale hunt.

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A drop in prey abundance

The fin whale’s habitat is intimately associated to its prey distribution. Any reduction in the availability of a certain type of prey could consequently be perceived as a loss of habitat. The various phenomena that could lead to a drop in prey abundance include climate change, competition with other animal species and commercial fishing.

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Pollution

There is no proof that baleen whales suffer from the toxic effects of the contamination of their environment by heavy metals and organochlorines. Yet, several immunotoxic chemical products appear to affect other marine mammals. Known effects of these pollutants on these animals include a weakening of their immune system, a lessening of their reproductive capacity, lesions and cancers. Disturbing organochlorine levels were detected in fin whale specimens from the Gulf of St. Lawrence in 1991 and 1992. However, recorded contaminant levels are inferior to those detected 20 years earlier.

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