Credit: Ros Cole
The first population assessment since the end of the whaling era reveals that New Zealand southern right whales have some way to go before numbers return to pre-industrial levels.
Reporting this week in Royal Society Open Science scientists from the University of St Andrews, the British Antarctic Survey (BAS), the University of Auckland, and Oregon State University explain how they used historic logbook records from whaling ships and computer modelling to compare population numbers.
The New Zealand southern right whale was particularly exploited in the nineteenth century when demand was high for oil extracted from its blubber. They were killed on the high seas and also in sheltered bays where females were vulnerable while caring for their young calves, making it easy for people to row out from the shore and kill them and for whale ships to hunt them on the open ocean. The term “right whale” was coined because they were so easy to hunt.
This latest research used current estimates of abundance and population increase to reconstruct the population’s trajectory over time. Estimates vary as to how many may have been killed. This latest research suggests there were between 29,000 and 47,000 before the nineteenth century and that this fell to a paltry 100 animals between 1914 and 1926. Today levels stand at less than 12 per cent of pre-industrial levels.
Credit: William Rayment
Dr Emma Carroll of the University of St Andrews’ Scottish Oceans Institute said: “The records of whale catches from the early nineteenth century are very patchy and we really needed to do a bit of detective work to get a good insight into the whaling history. We went back through early colonial New Zealand historical records and whaling logbooks, and even had to cross-reference what ships had been seen where to get an understanding of the scale of operations during the winter in New Zealand. This has given a good insight into whaling history in New Zealand and made this population assessment possible.”
Lead author, Jennifer Jackson, of BAS said: “The road to recovery for this species is proving to be long – we estimate it will be at least 60 years before this population is restored to pre-hunting numbers.”
Historical whaling records used in this research were compiled by the World Whaling History Project, which summarised records from American whaling logbooks and New Zealand government records from 1800 to the present as part of the History of Marine Animal Populations and Census of Marine Life (CoML.org) initiatives.
The research will be of vital importance in the planning of conservation strategies for this species and for the future protection of their habitats.
Notes to news editors
The paper ‘An integrated approach to historical population assessment of the great whales: case of the New Zealand southern right whale‘ by Jennifer Jackson, Emma Carroll, Tim Smith, Alexandre Zerbini, Nathalie Patenaude and C Scott Baker is published by Royal Society Open Science.
Photos available on request from the University press office.
Dr Emma Carroll is available for interviews from Tuesday (15 March 2016) afternoon. Please contact the University press office to arrange.
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