Scientists are calling for speed limits at key times of the year on fast ferries linking the Canary Islands as evidence mounts that they are linked to a dramatic increase in the deaths of sperm whales and other cetaceans.
It is feared that the catamaran and trimaran ferries which travel at up to 40 knots (46mph) can cut the whales in half and it is estimated that at least one whale is being killed each three months.
Researchers at the Institute for Animal Health at Las Palmas University believe the death toll may be higher than the local population of sperm whales can sustain.
Over the past 20 years, the Canary Islands Stranding Network has recorded almost 1,000 stranded or dead whales in the region. Around 80 of these animals had injuries consistent with ship strikes, such as deep lacerations, and 34 were confirmed to have been hit by a ship. Based on these two decades of observations, a whale in the Canary Islands is killed in a suspected collision every three months. Each year pathologists examine about 60 whales and dolphins that have either washed up on beaches or are found floating dead offshore.
Leading the team of pathologists is Antonio Fernandez, director of the Institute for Animal Health at Las Palmas University, who reports that fin whales, right whales, pilot whales and beaked whales have died in similar circumstances.
However, it is feared that sperm whales are most at risk. The death rate from collisions is thought to exceed the sperm whale’s reproduction rate of one per cent a year. A 2015 study estimated a population of 224 sperm whales in the archipelago.
Manuel Arbelo, a zoologist at the University of Las Palmas de Gran Canaria, presented details of the team’s research to the World Marine Mammal Science Conference in Barcelona, Spain, more than two years ago. However, since then the number of fast ferries working in the area has steadily increased and there are now more than 20,000 high-speed ferry connections a year between the islands.
Arbelo pointed out that the whales that wash up on beaches are ‘the tip of the iceberg’ of total deaths from ferry strikes as most would be lost to the ocean, and added, that if collisions continue at the present rate it could mean a significant decline in the Canary Islands’ sperm whale population.
On Friday the Tenerife Association of Friends of Nature (ATAN) called on the Spanish authorities to take urgent action to stop the collisions. In a statement, ATAN said it feared that post the Covid-19 lockdowns ferry traffic will increase even further and more cetaceans will die.
A spokesperson said: ‘There is clear and blunt scientific data on the impact of these collisions on protected species such as cetaceans, but still neither the Spanish nor the Canary Islands’ governments have taken measures to regulate sea traffic in a way that can reduce the mortality of whales in the Canaries.’
Scientists say the solution could be as simple as establishing seasonal speed limits in specific areas where the whales are known to congregate. Mandatory speed limits imposed on the east coast of the United States have been shown to be effective in reducing collisions with the North Atlantic right whale.
The Spanish government is financing a pilot project with ferry companies to develop thermal cameras that can detect the presence of whales. Tests have shown the technology is effective but Aguilar said they still needed to develop software to help to interpret the images and warn ship crews, while avoiding false alarms.
