TROUBLED WATERS - Whale and Dolphin Conservation Society

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9 The potential stress effects of whaling and the welfare implications for hunted cetaceans Barbara Maas, Chief Executive, Care for the Wild International, The Granary, Tickfold Farm, Kingsfold, West Sussex, UK. Whaling may impose physical and psychological stress even before any harpoon is fired. This may apply as much to whales that are struck and eventually killed as to those that evade capture. The IWC has, so far, restricted discussions on whale hunting to primary and secondary killing methods. However, from first sighting to the time when a whale is killed, the elements of pursuit, such as approach, duration, speed and distance covered may affect morbidity (defined as the incidence of disease or the occurrence of pathophysiological or degenerative changes) and mortality even among animals that successfully evade harpooning. Whaling operations and the potential for exertional stress and fear Whether whales experience stress as a result of being hunted depends on the level of exercise imposed on the animals. Øen and Walløe (1995) argued that because the top speed of most Norwegian whaling boats does not exceed 7-8 knots, this only permits a “slow stealthy approach when they try to position the boat next to the predicted surfacing of the whale” and so does not constitute a chase. Yet, according to the 1994 minke whaling summary report, “one [veterinary] inspector reported that a vessel had chased a whale for at least 6-7 hours. He proposed that a maximum permitted duration should be introduced for such chases.” (Government of Norway 1995). Minke whales normally swim at speeds of four to five knots but can maintain 20 knots for short spurts. Therefore, it would appear that Norwegian whaling boats can force minke whales to exceed their comfortable swimming speed and the potential for chase depends on pursuit duration and speed as well as distance covered. Japanese catcher vessels are faster than Norwegian boats and can both match and maintain a minke whale’s maximum speed. Thus, Japanese whale hunts have a greater potential to cause forced exertion. Eyewitnesses report that pursuit times of 30 minutes are not unusual in Japanese hunts, although 45 and even 90-minute chases also occur. In order to place a shot, the catcher boat must obtain a proximity range of 40-60 metres, and several hours may pass before this range is achieved (Tanaka 1987). It is routinely reported in Japanese hunts that a targeted whale’s respiratory rate is deliberately raised to shorten surfacing intervals, as this increases opportunities for harpooning. In aboriginal hunts, such as the hunting of gray whales in the North Pacific by the native Chukotka, it can take two to three hours to place the first of several harpoons (Zemsky et al. 1999). Zemsky et al. describe the duration of Chukotka hunts - “after a long chase of a whale, whalers have to stop whaling due to the impossibility to approach the animal at a near distance (sic)” (Zemsky et al. 1999). This suggests a race in which whalers try to get close enough to set the harpoon. The application of floats hamper a whale’s escape by slowing it down and impeding dives. Zemsky et al. (1999) list the The potential stress effects of whaling and the welfare implications for hunted cetaceans 69
70 A REVIEW OF THE WELFARE IMPLICATIONS OF MODERN WHALING ACTIVITIES “absence of ships and boats necessary for long-distance chases of grown-up whales capable of energetic and long resistance” as one of the factors impeding the 1998 hunt. However, “chasing a whale to exhaustion” is considered unacceptable in the Makah gray whale hunt (Ingling 1999). Fear is regarded as stressful in both animals and man and can compound the physical effects of stressrelated exertion (Broom 1985; Rushen 1986a, b; 1990). Biologically, fear can be understood in terms of sensory inputs related to previous experiences, or the unknown (e.g., Brambell 1965; Jones 1987; Hemsworth and Coleman 1998). The neuro-pharmacological system involved in fear and anxiety is the benzodiazepine receptor system, which occurs in all vertebrates except the agnatha (lamprey and hagfish). The manoeuvrability of the whaling boat and its movement in the direction of the whale or toward its anticipated surfacing area (see Øen and Walløe, 1997) are factors likely to influence whether the animal considers itself threatened. Threat perception can raise stress hormone levels and cause physiological changes. The significance of the whale’s perception of pursuit by whaling vessels was raised by Van Liere (see IWC/47/18). Van Liere emphasised the persistent and uncontrolled nature of pod disturbance associated with whale hunts and suggested that whales subjected to pursuit are likely to suffer stress. Øen (1995) on the other hand stated that in Norwegian minke whale hunts, whales are killed without the animals realising they are being hunted. Aboriginal whaling is invariably associated with a chase, utilises less effective weapons and ammunition and requires several harpoons with floats to tire and slow the whale (Øen, 1999, IWC/51/12, SC/51/AS29). Kills are therefore usually slow with the boundary between pursuits and kills increasingly blurred. Whales are pursued at least some of the time during commercial, scientific and aboriginal whale hunts. Current knowledge on cetacean hearing (Richardson et al. 1995) suggests that whales are aware of whaling vessels where they are about to surface. Predation is unlikely to have been a major selective force in the evolution of large cetaceans – nor are whales themselves predators that overwhelm their prey through prolonged pursuit. They may, therefore, not be physiologically adapted to ‘anti-predator’ behaviour involving prolonged and forced physical exercise. Although Norway reportedly carried out a pilot study examining stress hormones in minke whales (Øen and Walløe 1999), detailed hormone measurements have not been made available. Although elevated plasma cortisol levels (an indicator of stress) were not found, it is not known whether baseline measurements from undisturbed minke whales were used for comparison and if so how they may have been obtained. No significant differences in plasma cortisol levels between whales killed ‘instantaneously’ and those that survived between 1-13 minutes were found. The study concludes that plasma cortisol may not be a reliable stress indicator in minke whales. However, cortisol secretion in minke whales killed ‘instantaneously’ may already have peaked, and measurement of aldosterone level might have been of value. A study on the serum chemistry of minke whales by Ishikawa (1996) revealed results consistent with findings from animals with severe tissue damage. The study also found significant effects of sampling schedules and protocols (e.g., including the orientation of the dead whale during transport, sampling time and site and type of injury) on several blood parameters, thus confirming incompatibilities between rigorous scientific protocol and the limited procedural options associated with lethal whale research.
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Appendix II Colour plates ©Mark Vo
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Figure 13. Processing minke whales
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TROUBLED WATERS - Whale and Dolphin Conservation Society

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