Like many cetacean species very little is known about the pygmy sperm whale (Kogia breviceps) and dwarf sperm whale (K. sima). Even basic parameters such as respiratory rates and maximum breath hold have not been determined for these two species. The average respiration per minute, longest normal breath hold during recorded 30 minute respirations, and maximum breath hold during stressful situations were determined for two K. breviceps calves and one K. sima calf undergoing rehabilitation at Mote Marine Laboratory and Aquarium's Dolphin and Whale Hospital in Sarasota, FL. The two K. breviceps included a male which was believed to be a few weeks old when it stranded, and a female that was roughly a month old when it stranded. Data was collected during the three months that the male K. breviceps was in rehabilitation, and 15 of the 21 months that the female K. breviceps was in captivity. The third animal was a female K. sima calf that was less then a day old at stranding, and data was collected on it for the nine of the 15 months it was in rehabilitation.
Weekly average respiratory rates were determined, and significant regressions were found for all animals. For the first few weeks the animals were in rehabilitation, there was a period of rapid decline in the respiratory rate for all three animals. This period of rapid decline was followed by a period of a more gradual decrease in respiratory rate for the two K. breviceps, or an increase in respiratory rate for the K. sima. The initial rapid decrease in respiration rate is believed to be due to a high initial stress level from stranding and transport followed by acclimation of the animal into captivity. The period of more gradual change in respiration represents the basal respiratory rate and the ontogenic change for each animal.
The weekly average longest breath hold during the 30 minute sampling periods was determined for each animal, and a significant increase was observed for both the male K. breviceps (r2 = 0.597, P < 0.001) and the female K. breviceps (r2= 0.801, P < 0.001). The K. sima showed an initial increase, but then leveled off and began to decrease, which is believed to be due to behavioral and disease factors. The maximum breath hold during captures for health examinations were recorded for the two females, and the K. sima showed a greater potential (21.67 minutes) at a much younger age than the K. breviceps (17.55 minutes).
Environment, behavior, and the overall health of the animal all appeared to influence the average respiration rate and maximum breath hold time of these animals.
We would like to thank the staff and volunteers of the Dolphin and Whale Hospital for their many hours working with these animals and the college interns with the hospital that spent countless hours assisting with data entry. In addition, we thank the private donors and Mote Marine Laboratory and Aquarium for their support of the rehabilitation of these animals, and many other sick and injured dolphins and whales.