June 2017

By Danny Buss

Whales have had a pretty tough time throughout recent anthropogenic history. During the 17th Century, the Baleen Whales (an iconic group of large whales with baleen plates hanging from their upper jaw which they use to filter krill, zooplankton and other small fish species from the water) in particular, began to be targeted as a global resource. This was predominantly for oil (extracted from their blubber) to produce candles and lubricants, and to make whalebone stays from the baleen plates, which were used in corsets (Estes 2006). As whalebone corsets grew in popularity and the demand for whale oil increased to lubricate new machines developed during the industrial revolution, rates of whale exploitation grew exponentially across the globe.

Commercial whaling brutally hit Antarctica during the early 1900s, with the realisation that many iconic species, including Blue (Balaenoptera musculus), Humpback (Megaptera novaeangliae), Fin (Balaenoptera physalus) and Sei whales (Balaenoptera borealis) travel south and gather to exploit the high concentrations of plankton found there during the summer months. These Antarctic whale populations were massacred before “sustainable fishing” was even a concept. For example, records from a whale processing station at South Georgia estimated that 118,000 whales were slaughtered in only 19 years[1911-1930] (Baker and Clapham 2004).

And yet, this story of decimation may be turning into one of conservation success. Thankfully, throughout the period of commercial exploitation no one species was exploited to extinction. By 1946 a global convention for the regulation of whaling was signed, creating the International Whaling Commission, which in turn established guidelines for the whaling fleets and increased protection for the whales. By the 1970s, four species – Blue, Fin, Humpback and Sei, – had protection and by 1986 all commercial whaling was suspended (Tonnessen and Johnsen 1982). Since then, recovery has been evident for most whale species, albeit slow (Roman and Palumbi 2003; Baker and Clapham 2004).

Meanwhile, catastrophic events such as the near extinction of many of the Baleen species were a wakeup call that highlighted a pretty important question – how many whales were there before whaling began? We didn’t know, and without information about baseline population sizes, and studies to monitor changes in population sizes over time, how could conservation strategies be implemented, and population recovery rates accurately be predicted?

This leads me to the questions I am currently exploring as part of my role as research assistant at the University of Exeter and which I will investigate further during my PhD research at the British Antarctic Survey, commencing later this year:
1. Prior to commercial whaling, no monitoring of whale populations was in place. How many whales were there? Does anybody know?
2. If not, is it possible to accurately predict pre-whaling abundances of all whale species using historic whaling records? What other methods are currently utilised and what do we know so far?
3. Are there new methods which we could use to estimate pre-whaling abundances?

These questions are currently being tackled by our research team, led by Professor Dave Hodgson, at the University of Exeter. Using computer modelling techniques, our team is testing whether it is possible to make accurate predictions for all sorts of biological measures. For example, primate brain sizes – can we predict the brain size of one species based on data we have for other closely related species? Or if we know the wing length of 14 out of 15 closely related bird species, can we use this information to accurately predict the wing length of the 15th?

And we are applying the same techniques in an attempt to estimate pre-whaling abundances. To do this, I have gathered current global population estimates from the International Whaling Commission’s website, for all Baleen whales. We will begin by trying to predict the abundances of species for which we already have the data. If we can do this accurately, we can be more confident about our predictions for species for which the data is missing. This is very much ongoing research, but we hope that by combining information on known ecological traits such as prey type and reproductive rate, the extent of commercial exploitation, phylogenetic relatedness and current geographic range data (see figure 1) we may be able to produce accurate estimates of pre-whaling abundances, and in doing so provide vital information for the conservation of these charismatic species in the future.

References:

Alter, E.S., R. Rynes, and S.R. Palumbi. 2007. DNA evidence for historic population size and past ecosystem impacts of gray whales. Proceedings of the National Academy of Sciences 104(1): 15162-15167.

Baker, S.C. and P.J. Clapham. 2004. Modelling the past and future of whales and whaling. Trends in Ecology and Evolution 19(7): 365-371.

Estes, J.A. 2006. Whales, whaling, and ocean ecosystems. California: University of California Press.

Lubick, N. 2003. New count of old whales adds up to big debate. Science 301(1): 451-451.

Palsboll, P.J., Z.M. Peery, M.T. Olsen, S.R. Beissinger, and M. Berube. 2013. Inferring recent historic abundance from current genetic diversity. Molecular Ecology 22(1): 22-40.

Roman, J. and S.R. Palumbi. 2003. Whales before whaling in the North Atlantic. Science 301(1): 508-510.

Smith, T.D. and R.R. Reeves. 2003. Estimating historic humpback removals from the North Atlantic: an update. Journal of Cetacean Research and Management 5(1): 301-311.

Tonnessen, J.N. and A.O. Johnsen. 1982. The history of modern whaling. California: University of California Press.

Whitehead, H. 2002. Estimates of the current global population size and historical trajectory for sperm whales. Marine Ecology Progress Series 242 (1): 295-304.