Whale Strikes by Ships: Causes and Solutions
M.S. Coastal Zone Management
Collisions with ships are one of the leading causes of death for whales and are increasing. It is imperative to eliminate or greatly reduce whale mortality caused by ship strikes because even a few deaths may have a significant impact on severely endangered species, such as the North Atlanticright whale (Eubalaena glacialis). There are numerous proposed causes and solutions, but none that will completely eliminate the problem. New avenues must be explored.
Causes include cetacean biology, as well as anthropogenic. Biology related factors that may affect collisions include species, gender, physical condition, age, activity, time of day, season, changes in food location and availability. Suggested anthropogenic causes include increases in ship traffic, ship size and speed, hull configuration, and propellers.
Ocean noise is considered a multi faceted factor. Sound is the primary form of sensory perception for most cetaceans. The naturally noisy ocean is increased by anthropogenic sources of noise which have increased over the years. Of greatest concern is active sonar used by a variety of users, but of most impact are the navies around the world. The U.S. Navy has been involved in ongoing disagreements regarding their use and the detrimental effect of sonar on cetaceans. Sonar is believed to disrupt their normal behavior and hearing, making them more vulnerable to ship strikes.
From the plethora of data, a “typical” whale strike can be constructed. The profile shows the following characteristics: a young fin whale (Balaenoptera physalus) injured by blunt trauma likely carried into port on the bow of the ship in theMediterranean Sea.
Proposed solutions include an audible whale deterrent, changes in vessel design to reduce noise, and reduction in noise producing activities. It is believed that if whales can be located, they may be avoided. Thus, solutions for locating whales include tracking whales by tagging, electronic monitoring, passive acoustic detection, active sonar, radar, and infrared detection. Changes in vessel operation include shifting shipping lanes. They also include a reduction in speed which is seen by many as one of the most viable solutions, but is not eagerly embraced by the shipping industry. Because voluntary speed reduction compliance was violated extensively, the reduction in speed became mandatory.
Suggestions for further research include changes in vessel propulsion to reduce noise and injuries, changing the frequency of some shipping noise, a device to attract whales away from vessels, new sensors and software for locating whales, dual use of security sonar, use of virtual training to replace live sonar training by Navy, and relocation of more shipping lanes.
Because the ocean is not a discrete entity, divided by country, there must also be an international policy solution. TheU.S.needs to ratify the U.N. Convention on the Law of the Sea in order for the country to take a leading role in international solutions.
Just as there may not be a single definitive cause of whale strikes by ships, there may also not be a single solution. There may very well be a combination of several solutions. No matter the solution or solutions, implementation will require international cooperation, and the results will be for the benefit of all.
Holly R. Hubbell. 2011. Whale Strikes by Ships: Causes and Solutions. Capstone. Nova Southeastern University. Retrieved from NSUWorks, . (140)