As international maritime traffic continues to grow and the speed of ships increases, the risk of collisions is also increasing, with serious consequences for species such as whales.
- Identify the effects ship strikes have on marine species
- Compare and distinguish legislative regulations to reduce the threat of ship strikes
Ship strike: A collision between a vessel and a marine mammal causing injuries to or death of the marine mammal.
Motorized vessel collisions with whales appear to have begun late in the 1800s and remained infrequent until the 1950s. The earliest known account involved the steamship Munroe in the United States in 1887. From 1975 to 2002 there were nearly 300 documented cases, with the actual number of strikes much higher, as many go undocumented or unreported.
Collisions are a significant source of mortality for some whale populations with the worldwide frequency of collisions increasing. The highest number of incidents have been reported for fin whales, northern and southern right whales, sperm whales and humpback whales.
Ship strikes may occur anywhere where vessel and whale distribution overlap, especially coastal urban areas in the proximity of whale feeding or breeding grounds. Injuries to whales take two forms: propeller wounds and blunt trauma injuries.
While the impact of ship collisions on whale species is not sufficiently documented, the threat to the endangered North Atlantic right whale is apparent with an average of two deaths or serious injuries per year caused by collisions.
National regulations to reduce the threat of ship strikes have been implemented by two countries, USA and Canada.
Effects of Ship Strikes on Whales
All whales are considered to be sensitive to ship strikes. Reports of ship collisions have been recorded for at least 21 species of large whales, with the occurrence of strikes happening in coastal areas.
Propeller wounds are characterized by external gashes or severed tailstocks. While blunt trauma injuries can be indicated by fractured skulls, jaws, and vertebrae, and massive bruises.
Threat to Whale Populations
The endangered North Atlantic right whale for example, is too slow or buoyant to swim away from ships or unaware of its surrounding. With less than 400 right whales remaining in the North Atlantic (2010), this population is in danger. This is evident as since 1991, about half of all recorded right whale deaths have been attributed to ship strikes.
Regulations to reduce the threat of ship strikes have been implemented by the USA and Canada. These regulations include:
- In 2006, the IMO approved a proposal from the US to reconfigure the "Traffic Separation Scheme" (TSS) that services Boston, Massachusetts. It involved a 12-degree shift in the northern leg and narrowing the two traffic lanes by approximately one-half mile each way.
- Self-propelled ships 300 gross tons or greater must report in when entering designated right whale reporting areas along the U.S. East Coast.
- All vessels 65 feet (19.8 meters) or longer must travel at 10 knots or less in certain locations (called Seasonal Management Areas or SMAs) along the U.S. east coast at certain times of the year to reduce the threat of vessel collisions with endangered North Atlantic right whales.
- The purpose of this mandatory regulation is to reduce the likelihood of deaths and serious injuries to these endangered whales that result from collisions with vessel.
- Because vessels of all sizes can strike a whale, NOAA Fisheries also encourages vessels less than 65 feet in length to help protect right whales by slowing to 10 knots of less within active SMAs as well.