Abstract: The food consumption (recorded as kg of individual fish species), body length, and body mass of 19 (four males and 15 females) Atlantic bottlenose dolphins (Tursiops truncatus) kept at Harderwijk Marine Mammal Park, the Netherlands, between 1965 and 1995 are reported. This broad-scale, longitudinal study is based on data originally archived for short-term husbandry purposes. The chemical composition and caloric value of the diet were not measured. Because caloric content of fish varies seasonally and annually, and depends on the geographical region where it was caught, the food intake variations seen in this study may reflect the caloric content of the diet. However, because the effects of age, gender, and reproductive state are consistent in various animals, and all animals entered the study at different times, the effects are believed to be independent of variation in caloric content of the diet. After weaning, the average annual food consumption of males and nonpregnant, non-lactating females increased rapidly until the estimated age of 3-5 years, thereafter it averaged around 1900 kg (estimated at 133 × 105 kJ) per year. After the age of 20 years, food consumption of several dolphins decreased slightly. Two females reproduced and nursed their calves successfully. Twelve months before parturition, consumption by both ceased almost entirely for one week, probably indicating estrus. Food intake did not increase during pregnancy. After they gave birth, the food consumption of the two mothers showed a comparable pattern; the food intake remained at a consistent level during the month of birth, but increased rapidly in the following month. Food consumption dropped during the third month of lactation in one case and during the fourth month in the other case. During the lactation period, the mothers consumed 2600 kg (48%) and 3300 kg (72%) more than during similar periods in non-reproductive years. The two calves began to eat fish, in addition to suckling, at the ages of 6 and 19 months respectively. Average standard body length at birth was 116±6 cm for males (n=15) and 114±10 cm for females (n=6). It increased rapidly until around the age of 5 years, after which growth rate declined. Body length reached an asymptote (between 260 and 280 cm) between the ages of 15 and 20 years. Average body mass at birth was 18.0±3.8 kg for males (n=15) and 15.6±4.9 kg for females (n=5). Weight gain was rapid until around the age of 3 years, after which it decreased. The relationship between body mass and standard body length was: Body mass (kg)=12.904e0.017(body length (cm)- 100). There was a negative relationship between body mass and average daily food consumption expressed as a percentage of body mass. The average initial passage time of food through the digestive tract of five animals (with an average body mass of 185 kg) was 235 min.
Key Words: BOTTLENOSE DOLPHIN; CARMINE RED; ENERGETICS; FEEDING; INITIAL PASSAGE TIME; NUTRITION; ODONTOCETES; REPRODUCTION; WEANING; GROWTH; BODY MASS; BODY LENGTH; TURSIOPS
Document Type: Research article