Scientists have old whalers turning in their watery graves
Scientists are using centuries-old whalers' data from the southwestern Pacific & Tasman Sea to help better protect threatened whale species.
American offshore whaling maps, log books and strike documents from 1700s to 1920s are being re-analysed to shed light on southern right whales and sperm whales in Australasia.
These historic data, combined with oceanographic information will allow scientists to define the oceanic habitat preferences of these threatened species. The data include about 46 000 locations of strikes or sightings of the whales as well as the locations where the whalers searched for, but didn't observe them.
These data will also provide insight into the distribution and movements of endangered whale species before their numbers were reduced to what they are today.
"We are using these data, that are over a hundred years old, to tell us what the key foraging, migratory, and frequently used habitats were for southern right whales and sperm whales, because abundance levels were high in the 19th century before heavy whaling," says NIWA marine ecologist Dr Leigh Torres.
Whaling was big business in the 1830s, so very detailed records were kept. Using these historic records, Dr Torres has begun to analyse the old whalers' data for comparison with the distribution of whale sightings today.
Dr Torres is developing models, based on these historical data, that will be used to predict modern-day habitat use patterns of these two whale species. "Using data from a long time period and a large area, we hope to predict where whales are within tens of kilometres during certain months," says Dr Torres.
The models will be used to predict habitats for these whales. Such information can aid conservation efforts. Dr Torres will match the predictions of modern whale habitats with localities of known threats to these populations such as fishing activities, noise, shipping traffic, and hunting pressure. This will be done over a wide area and with many years of data to highlight areas that may need increased management, protection, or monitoring.
Shipping traffic frequently kills whales. Whales also get caught in fishing gear, including long lines and set nets. Ocean noise from seismic exploration and oil drilling is increasingly becoming a concern as whales rely on acoustics for communication and navigation.
Southern right whales are nationally endangered, and are in danger of extinction as there are scarce numbers of these whales within our waters. Prior to the 1830's there were an estimated 27 000 southern right whales within New Zealand waters, and now there is an estimated 5000.
Sperm whales are classified as threatened which means that they are likely to become endangered. The numbers of sperm whales in New Zealand waters are unknown, but a recent global estimate was about a million whales during the pre-whaling era, with about 32% of this original population level remaining in 1999, 10 years after the end of large-scale hunting. The percentage reduction in New Zealand waters is likely to be similar.
This project is being funded by Australian Antarctic Division's Marine Mammal Centre and NIWA.
The American offshore whaling document data were compiled by Tim Smith of the World Whaling History project that is describing the effects that whaling has had on populations of whales over the centuries and throughout the world's oceans.