With the relentless increase in shipping on our oceans, it is recognised that the threat this poses to whales has also increased. Various attempts have been made to try and mitigate the damage to cetaceans caused by shipping, but a new initiative by British scientists is the most promising yet.
The Dangers to Whales from Shipping
Strikes by ships are a major factor in whale deaths globally. Any ship can potentially be a danger, but the severity of injury broadly increases with ship size and speed of travel.
The North Atlantic right whale is particularly at risk from ship strikes. This whale seems to be even less able than other cetaceans to relate the approach of large ships to the danger they pose. A report by Knowlton and Kraus (1992) states that between 1970 and 1989, twenty percent of the northern right whales found dead had evidence of ship strike injuries. Humpback whales, fin whales, sperm whales and grey whales are also very susceptible to ship strikes. Injuries from ships include impact fractures, skull damage, and deep gashes from propellers.
Marine creatures, including whales, are extremely sensitive to noise pollution from the sonar and engines of ships. Sound travels further and more easily in water than in air. Noise from shipping can interfere with the ability of whales to echolocate, that is, to use sonar in order to locate prey for feeding. They also rely to an extent on echolocation to search for a mate. Disruption of either of these behaviours is clearly a threat to the survival of affected species of whale.
Attempts to Avoid Damage
There is something horrifying and saddening when these wild, wonderful creatures are maimed or killed by human activity. Researchers and conservationists are busy trying to find ways to minimise the danger. The WDC (Whale and Dolphin Conservation) group report that propeller guards and acoustic detection systems have had some limited success. So far however, the most effective way of protecting whales is to limit shipping to 10 knots or less in areas where whales are known to be at the time.
Still, the problem remains that identifying with any accuracy where whales will be is not an easy task. This is why there is great interest in the recent innovative work by the British Antarctic Survey team.
Tracking Whales from Space
This potentially game-changing development was widely reported at the beginning of November 2018. Peter Fretwell, of the British Antarctic Survey (BAS) team, told CNN News,
“Most whale populations have been increasing after they were hunted almost to extinction in the 20th century, but some whale populations are struggling and that’s because of things like ship strikes and net entanglements,”
The team have taken images from the WorldView-3 spacecraft which, even from 620km up, give very high-resolution pictures. The images are so detailed that the species of whale pictured can be identified, and accurate counts made of whales in the surveyed location.
Initially, this technology will be used to conduct an audit of fin whales in the Mediterranean. However, the potential is there to develop a system which can alert ships, in real time, to the exact location of any groups of whales near the ships’ paths. This would be a welcome development in the effort to protect whales.