This article titled “Revealed: whale-watching boats the greatest collision threat to whales” was written by Paul Farrell and Nick Evershed, for theguardian.com on Friday 27th June 2014 01.25 UTC
Whales are more likely to to be hit by whale-watching boats than any other identified vessel type, data from the International Whaling Commission shows.
Whale collisions around the world have been collated by the commission in a database which runs from 1885 to 2010.
While the type of vessel is unknown in most incidents, where the boat type was identified the highest number of collisions came from whale-watching vessels. Motor yachts, naval vessels and ferries came close behind. This could be due to the reporting of incidents being skewed by certain vessel types being more likely to report a strike.
Whale watchers are the most likely overall to hit whales when counting all collisions, but when analysed by injury outcome, naval vessels were most likely to cause death, and whale-watching vessels were highest for injuries.
Whale watchers in Australia were warned this week to be cautious, as humpback whales migrate from the antarctic to warmer waters.
Mark Read, the Great Barrier Reef marine authority’s conservation manager, said watchers should always keep a safe distance.
“These giants of the deep never cease to amaze, even for people like whale researchers or tourism operators who are lucky enough to have interactions with them each year,” Read said.
“But given the growth in recreational vessel registrations and the popularity of commercial whale watching, it’s becoming increasingly important for people to abide by approach distances.
“Vessels need to stay more than 100m away from a whale, while in the Whitsundays whale protection area the distance is 300m.”
Most recorded whale collisions took place off the east and west coasts of the US. The number of contacts off the US coast was fives times higher than the second highest recording by country, which was Australia. Hawaii, Canada, France and New Zealand also had a number of collisions.
Fin whales, humpback whales and north atlantic right whales were the most likely type of whale to be hit by vessels in the water. The extent of many injuries was unknown, but a quarter of all recorded collisions led to the death of the whale.
The number of whale strikes peaked in 2006. This may be a function of observations increasing, as well as an increase in both the human and whale populations over this time.
The humpback whale population in Australian waters was decimated because of whaling but has recovered significantly since the practice was restricted in 1979.
The University of Queensland has studied Australia’s east coast humpback population for the past 30 years by surveying the number of whales passing each day during their migration period each year. Their analysis shows the number of sightings increased from six every four weeks in 1984 to 84 every four weeks in 2010. Based on the number of sightings in 2010, there was an estimated population of 14,522 humpback whales on the east coast.
“The main reason for the higher rates of growth is they were hunted down to their last 1%, and all we really had to do was stop hunting them, and then they started rebounding by themselves. In the Australian case that’s been a fairly rapid recovery,” said Dr Michael Noad, a senior lecturer at the University of Queensland.
“It’s very hard to get data on many species of whale. Humpbacks are the exceptions, because they migrate across the coastline. Many other species spent their time out in the deep archipelagic regions which makes it much harder to gather data.”
Unfortunately a recent study showed the sperm whale population migrating through Australian waters has failed to recover in a similar fashion.
• This post was amended to emphasise that certain vessel types may be more likely to report incidents, and therefore be over-represented in the whale strike database. An incorrect caption credit was also removed.
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