In NewScientist (“There She Blew!”, 5 November 2016, paywall)
Using Bayesian statistics to account for uncertainties in modelling population dynamics, Smith and his colleagues have also reconstructed the historical abundance of these whales. Their analysis suggests that before widespread commercial whaling, southern right whales around New Zealand numbered somewhere between 29,000 and 47,000 – a range corroborated by the genetic diversity we observe today. Following 19th-century harvesting, they almost disappeared, with mature females plummeting to 40 or fewer individuals in the early 20th century. None were seen between 1928 and 1963. And although numbers are now slowly recovering, the population still hovers at no more than 12 per cent of pre-exploitation levels.
Morgana Vighi at the University of Barcelona, Spain, has also used logbooks to track the fate of southern right whales in the south Atlantic. Looking at entries from whaling grounds off the coast of Argentina and Brazil, she charted a decline between 1776 and 1923, as well as seasonal north-south and inshore-offshore movements. “In the early period of whaling, the sightings were spread along the coastline of South America,” says Vighi. Now things appear different. Chemical signatures she has found in modern bone samples from whales living off Brazil and Argentina suggest that whaling may have caused a schism, splitting what was a single population into northerly and southerly groups.
At the French National Center for Scientific Research in Montpellier, Ana Rodrigues and her colleagues have estimated historical numbers of north Atlantic and north Pacific right whales. “The logbooks are an amazing data source,” she says. Her team has concluded that before commercial whaling, the former numbered between 9000 and 21,000, and the latter between 15,000 and 34,000. So intensively were north Pacific right whales hunted that the population crashed after 1840. “In 10 years, they nearly exhausted the entire stock,” says Rodrigues.
And to what logbooks do they refer? Those at the New Bedford Whaling Museum:
Welcome to the general citation search page for the logbook and journal collection of the New Bedford Whaling Museum Research Library. The Museum’s logbook and journal database has been recently updated and can be downloaded (an excel spreadsheet) by clicking on the the text link. This database is not set up for detailed subject searches. However, subject searches are possible through the Search Library page of the Museum’s website.
If citizen science appeals to you, you can help translate old weather logs here.
