The waters around Okinawa are a breeding ground for humpback whales. The Okinawa Churashima Foundation Research Center has been studying humpback whales, and confirming their presence from January through April each year for 21 years (1991-2012).

During our research, we observe the behavior of the humpback whales. By using individual identification methods, we can identify individuals by the characteristics and shapes of their flukes, tailing edges, and ventral area. Through this method we have distinguished 1,284 individuals that were identified by their gender, and noted the location, date of appearance and the group composition: lone whale, pairs, groups of three or more, and groups with calves.

From our results, we now know that from the end of January to the end of February (the beginning of the whale season) there are many pairs of male and female humpback whales, and mating groups (whales of mixed sex in groups of three or more). Mother and calf pairs are often spotted from the middle of February, through March, and increasingly at the end of the whale season.

Our research suggests that humpback whales frequently pass through Okinawa during January and February at the height of mating activity. After a year long pregnancy, they give birth during or just after February.

ザトウクジラの尾びれ

Authors’ names

Nozomi Kobayashi, Haruna Okabe, Isao Kawazu, Naoto Higashi, Hirokazu Miyahara, Hidehiro Kato, Senzo Uchida (Bold letters：Foundation staff member)

Title

Peak mating and breeding period of the humpback whale (Megaptera novaeangliae) in Okinawa Island, Japan

Journal

Open Journal of Animal Sciences

DOI

http://dx.doi.org/10.4236/ojas.2016.63022