Ship speed key to protecting New Zealand’s resident Bryde’s whales
While we don’t always like to slow down when we’re out for a drive, most of us appreciate the need reduce our speed; we don’t hesitate to comply with speed limits in school zones, for example. Just as pedestrians are more at risk of fatal injuries when hit by vehicles at higher speed, it’s the same for whales in busy shipping lanes.
Sad news emerged from New Zealand recently of another Bryde’s whale washing up dead in the Hauraki Gulf, outside of Auckland. Necropsy results confirmed the whale was killed by ship strike.
Ship strikes have been identified as the main cause of mortality for Bryde’s whales in Hauraki Gulf. There have been over 40 recorded deaths in recent years. For those where cause of death could be determined, all but two were attributed to ship strikes.
The Hauraki Gulf has one of the few known resident populations of Bryde's whales in the world (Bryde’s whales are generally thought to be migratory animals). This critically endangered resident population may number fewer than 200 so even a few deaths from ship strikes could have a dramatic effect on this population of these long-lived whales.
Thanks to the work of researchers at the University of Auckland, we already know how these whales use the Gulf and what makes them so vulnerable to ship strikes. The same research has shown us that successful solutions used elsewhere in the world, like re-routing ship traffic or using acoustic warnings as pioneered by IFAW in the north Atlantic, would be limited in their effectiveness.
However, research also clearly shows that reducing ship speeds results in fewer fatalities. There is over an 80% chance that a whale struck by a ship travelling at 16 knots will be killed; this probability is reduced to less than 25% at 10 knots.
That’s why IFAW is teaming up with New Zealand researchers, NGOs, government agencies, iwi and the shipping industry to identify solutions. We’ve been encouraged so far by the response of the shipping industry, who have engaged willingly and constructively in discussions. We’re hopeful that as this work continues it will identify ways to better protect these special residents of Hauraki Gulf.