Gonadal material throws light on the cetacean's reproductive health, blubber thickness reflects the animal's general health while gut contents reveal much about a cetacean's diet.

First, researchers worry that including females in their experiments will increase variability — females have fluctuating gonadal hormone levels — thus necessitating the testing of more subjects.

Nor do they know how long gonadal resting phase between spawning events last or how long it takes an egg to reach maturity.