HUMPBACK WHALES MEGAPTERA-NOVAEANGLIAE IN THE ARABIAN SEA

The population identity of humpback whales Megaptera novaeangliae in t he Arabian Sea has long been a matter of dispute. New information is p resented from this region, based upon whaling and observations conduct ed by the Soviet Union, primarily in November 1966. In that month, a t otal of 238 humpbacks were killed off the coasts of Oman, Pakistan and northwestern India; 4 others were killed in 1965. Biological examinat ion of these whales showed that they differed significantly from Antar ctic humpbacks in terms of size, coloration, body scars and pathology. In addition, analysis of the length distribution of 38 foetuses indic ates that the reproductive cycle of the Arabian Sea whales was unequiv ocally that of a northern hemisphere population. Mean lengths were 12. 8 m for males (range: 9.5 to 14.9 m, n = 126) and 13.3 m for females ( range: 9.5 to 15.2 m, n = 112). All whales 12.5 m or more in length we re sexually mature. Among 97 females examined, 12 (12.4%) were immatur e. Of the 85 mature females, 39 (45.9%) were pregnant, 3 (3.5%) were l actating, and 43 (50.6%) were resting. A more plausible pregnancy rate , adjusted for underrepresentation of lactating females, was estimated at 39%. A majority of stomachs examined contained food, including eup hausiids and fish. Overall, the data presented here argue strongly tha t Arabian Sea humpbacks constitute a discrete population which remains in tropical waters year-round, a situation which is unique for this s pecies.