HOPE report

Number: 25-015

Study on the interactive behavior of captive sea otters (Enhydra lutris)

Report: Rei Sumitani

Date: 2014/1/10 - 2014/3/20

 The reproductive rate of wild sea otters (Enhydra lutris) is said to be relatively stable. However, breeding under captivity has not been as successful, and few studies have focused on the reason behind this phenomenon. In order to gain a better understanding of sea otters under captivity, I visited the Seattle Aquarium, Washington, to conduct behavioral research. Here, one adult male and three females are kept in the same pool, therefore both female-female and female-male interactions can be studied. Observations were conducted from the passageway outside the sea otter exhibit using a video camera. Most observations were conducted between 9am and 5pm. Two night observations were also made.

 Interactions between the male and the female pup were the most commonly observed, while those between the male and the adult females were rare. Female-female interactions consisted of wrestling and nursing, and were also relatively rare. Several different types of male-female interactions could be identified, including wrestling, paired logrolling, nose biting, mutual porpoising, and penetration. During my visit, I also learned the procedures for fecal hormone analysis, including preparation of fresh fecal samples and analysis of corticosterone, testosterone, and progesterone. I will now analyze the behavioral data in depth, and examine the pattern of behavior and their relation with hormone fluctuations.

The four captive sea otters observed

Hormones analysis of the fecal samples

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