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22 Jun 06
Your whaling questions answered
Greg Donovan is the head of science at the International Whaling Commission (IWC). His job is to provide detailed information on whale species to member states so that they can take decisions that are based on good science. On this page, he answers some of your questions.
Can some species of whale realistically be harvested in a sustainable way? ( Question provided by Anna Dennis, Southampton; and Alan Kieran, Sydney; among others.)
From a scientific perspective, the IWC Scientific Committee has developed probably the most rigorously tested way to estimate safe catch levels for any marine species. The approach, called the Revised Management Procedure (RMP) for commercial whaling, would allow very limited catches of only abundant populations. Catch-limits would not be set by species but by populations (e.g. the common minke whale in the northeastern Atlantic) and only for five-year periods before being reviewed. It has strict minimum data requirements and takes scientific uncertainty into account. Regular (5-6 years) abundance estimates are required.
A similar process is used for aboriginal subsistence whaling called the Aboriginal Whaling Management Procedure (AWMP). At present, the RMP is not being used. Although the IWC has agreed that it provides safe catch limits, it has not agreed on a set of rules to allow it to be used.
Taking into consideration the cultural differences between IWC members and the scientific findings for and against whaling, can you predict a resolution to this issue? ( Question provided by Julie, Bristol; and others who questioned the ethics of whaling and the role of science in the decision-making process. )
I believe that the views of a scientist on the political and ethical issues surrounding whaling (or indeed any issue) are worth no more or no less than anyone else's. In my opinion what we should do as scientists is to provide the best scientific information we can (on the numbers, trends, possible threats etc) and be honest about scientific uncertainty. That information can then be used to inform politicians, managers and the public who can then make a political decision. At least in theory, good scientific information is perhaps the only way we might have a chance to bridge the cultural divide on this and other issues. There is, of course, always the problem that politicians on all sides 'selectively' quote only the scientific advice that suits there predefined political position.
Is the relative scarcity of different whale species taken into account when determining which can be caught for "scientific research"? Are stocks of whale species recovering overall? ( Question provided by Daniel, New Zealand; Bonnie McBride, London; Seb Beloe, London; and others. )
For some populations of some species, we don't have good information on numbers. However, for other populations we have good estimates of present numbers and trends in abundance. As whales spend much of the time underwater, estimating their abundance is not easy and we use a number of different techniques from vessels, aircraft and sometimes from land (when animals all migrate very close to shore past a single point). That is why when we estimate numbers of whales, we also estimate the inevitable scientific uncertainty surrounding the numbers. So for example, we give a range (or 95% confidence limits) with a "central" estimate such as 8,000 (6,000-10,000). When giving management advice we always act in a precautionary way and give most weight to the lowest number.
The most endangered populations of large whales include the western North Pacific gray whale (about 120 animals) and the western North Atlantic right whale (about 300 animals). Both of these populations were reduced to very low levels by old "Yankee" whaling in the 19th Century.
The greatest threats to them now are bycatches in fishing gear, collisions with ships and potential damage to their habitat.
On the bright side, we have good evidence that a number of populations are increasing since they were reduced by whaling. These include several populations of Southern Hemisphere humpback and right whales, eastern North Pacific gray whales and western Arctic bowhead whales.
What account is taken of the possible impact of climate change on future whale populations, as oceanic current patterns change, sea-surface temperatures shift, and food chains become changed and/or disrupted? ( Question provided by Philip de Jonge, Liphook; Rob, Oxford among many others. )
To predict the influence of climate change on the abundance of future whale or dolphin populations is extremely difficult. There is considerable uncertainty about the effect of such changes at all levels of the ecosystem, from plankton to large predators. Indeed, there is considerable uncertainty about the local-level effects of climate change. Species that are flexible in their habitat requirements or have an ability to relocate if things change within their normal range will be best able to cope. Considerably more research is needed before we are in a position to make useful predictions. This emphasises the need to continually monitor not just whales but as many parts of the ecosystem as possible. Only with better data can we make long-term predictions. In the case of providing advice on hunting, then both the RMP and the AWMP (read my first answer to see what those are) require regular abundance estimates to be obtained to ensure that things are not going wrong. They have also been tested by computer simulations to see how they perform when there are changes in the habitat that result in much poorer conditions for whales, and when there are occasional disasters (e.g. disease) that result in large numbers of animals dying unexpectedly in a single year.
Greg Donovan is working through more of your questions. Come back later to read his answers. You can also find more information at the IWC office website
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