Ship strikes of cetaceans are an issue of growing concern internationally. With the increase in the number, size and speed of ships, the threat of ship strikes of cetaceans may also increase and thus there have been calls for the Organization to take action to minimize this threat.
Collisions between cetaceans and ships occur worldwide where there is an overlap between cetaceans and vessel activities. Such collisions involve a wide variety of vessel types, including recreational, commercial and governmental vessels. Damage to vessels, ranging from minor to extreme, has resulted from ship strikes of cetaceans. Such damage includes cracked hulls; damaged propellers, propeller shafts, and rudders; damaged port and starboard aft strut actuators; broken steering arms; and ruptured seawater piping. In some cases, in particular involving large vessels, captains may be unaware that a collision with a cetacean has occurred.
Although the vulnerability among species varies, a wide variety of cetaceans have been involved in ship strikes. Evidence of a strike has been noted by blood in the water; animals seen with cuts; propeller gashes or severed tailstocks; animals observed sinking after strikes indicating death; fractured skulls, jaws, and vertebrae; or haemorrhaging, massive bruising or other injuries noted during a necropsy of an animal. There are gross and histological evidence of sharp and blunt trauma in such species as fin whales (Balaenoptera physalus), and sperm whales (Physeter macrocephalus) killed by vessels. Improvements in necropsies have resulted in the ability better to identify when a ship strike results in the death of a whale. Notwithstanding, many animals subject to ship strikes likely go undetected or unreported because ship strikes may occur in remote areas or the carcasses may sink or drift out to sea.
In a marine region where vessel traffic and other human activities are as intense as in the Agreement area, disturbance is also a source of considerable concern for the continued survival of cetacean populations. However, again, the need for a better understanding of the mechanisms affecting cetaceans and their long-term effects on populations appears as imperative. The potential of vessel traffic, collisions with ships, noise from various sources (shipping, industrial, coastal construction, dredging, mineral prospecting, military, etc.), and a growing commercial whale watching industry, to negatively affect the status of cetaceans in the Agreement area adds to the threats described above.
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Last Updated (Tuesday, 03 July 2012 08:05)