The most dramatic expansion in Southern Ocean whaling took place over only three seasons between 1927 and 1931, when the effort and catches quadrupled (T0nnesen and Johnsen, 1982). In 1930-31, there were 6 shore stations, 41 factory ships and 238 chasers involved in Antarctic whaling. 40,201 whales which produced 3,608,348 barrels of oil were caught in that season alone. Despite a lull in the depression years caused by over-production, low prices and reluctant forward-buying of oil, catches continued to increase throughout that decade. Figure 9.5 shows the areas of the Antarctic Sector of the Pacific that modern whalers concentrated on.

Fig. 9.5. Areas of modern (post-1900) whaling (light hatching). Darker hatching corresponds to concentrated catch zones (after Gaskin, 1977).

In the Ross Sea, blue whales abounded, and therefore represented most of the catch. However, there were soon signs of over-catching - younger whales being caught, and the proportion of different species in the catch were changing. More fin and sei whales were appearing on the records.

In the 1930s, an international agreement was reached which limited the whale catching season in the Southern Ocean to 3 months. It also afforded female whales and calves protection, and prescribed humane (as they were thought to be then) methods of killing whales. Although there were many cries for some stronger form of conservation of whale stocks, the number of whales caught was not controlled until much later when the International Whaling Commission (IWC) was formed in 1946 (McHugh, 1974; Gulland, 1988). Annual catch quotas also served to prevent over-production of whale oil and corresponding market instability. Even during the war years, 46,656 whales were caught in southern waters. Many of the old factory ships were damaged or destroyed during the 1940s as they were pressed into service to support the war effort. The post-war years saw big development of new ships, and the entry into Southern Ocean whaling of the new modem whaling nations Russia and Japan.

Catches in the Antarctic Sector of the Pacific averaged 6,151 whales a season between 1946 and 1964, reaching a peak of 12,979 in 1956-57. Britain, Norway and the Netherlands found the poor catches of the early 1960s uneconomic, and by 1964-65 had given up sending whaling fleets to the Southern Ocean, leaving the grounds for Japan and Russia. It has been estimated that almost 1.4 million whales were removed from Antarctic waters between 1904 and 1978 (Tonnesen and Johnsen, 1982).

The graphs in Fig. 9.6 show the numbers of different kinds of whales that were caught annually in the Antarctic Sector of the Pacific between 1946 and 1986 (data courtesy Dr. R. Gambell, International Whaling Commission). The graphs demonstrate the successive concentration of catching on humpback, blue, fin, sei and minke whales as each species was depleted.

From 1979, the small minke whale was the only species allowed to be caught in Antarctic waters under the International Whaling Commission's regulations, and since 1986 there has been a total moratorium on commercial whaling in the Antarctic. There is, however, provision in the International Convention for the Regulation of Whaling for the taking of whales for scientific purpose. Japan has continued to catch minke whales (241 in 1989) in the interests of scientific research.

There is now considerable opposition to "scientific whaling" amongst the IWC nations, and, at the 1988 Commission meeting in New Zealand, 10 nations co-sponsored resolutions opposing the issuing of special whaling permits. It has been argued that it is necessary to catch whales to provide the basic data for monitoring the status of populations and the age and reproductive status of individuals. However, new methods of sampling whales are being developed which may reduce the need to kill the animals. For example, the technique of genetic "fingerprinting" can be applied to whales (Hoelzel and Amos, 1988). A small plug of body tissue painlessly removed by a dart can identify an individual, patterns of paternity and, in some cases, maternity, and be used to assess the amount of genetic variation with populations of whales. There are also new benign study techniques involving photo-identification of whales, and analysis of their vocalizations, which, for some species, can provide data on migrations, population sizes and life histories.

Fig. 9.6. Numbers of whales caught in the Antarctic Sector of the Pacific Ocean, south of 40°S, between 1946 and 1986 (from IWC data).

Gambell (1987) has reviewed the effects of exploitation on the whale stocks of Antarctica and has pointed out that, although there is some strong evidence that both pregnancy rates and age at sexual maturity have changed in the big baleen whales since the main reductions in numbers took place, there is little sign of an increase. Current doubts over the estimates of the numbers of whales, and the rates of growth and recruitment, have made it difficult to draw any firm conclusions about the impact of changes in the whale population sizes on both the whales themselves and their ecosystem. Gambell suggested that the advantage now taken by competing species (other krill-feeders) may actually prevent the recovery of whale stocks.

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