Gray Whales: Recruitment
Wayne Perryman, Biologist

What does "recruitment" mean? If a population is going to grow or even remain steady, enough new animals need to be born to replace those that die. So the more calves you get in excess of the natural mortality level, the more the population can grow.

In order to reproduce, adult females have to be very healthy. Their health is impacted by how much they get to eat during their 6-month feeding season. Sometimes things like weather can either shorten or lengthen the feeding season. For instance, if ice is slow to melt, it can form a physical barrier between the whales and their feeding ground. That means the whales will have less time to feed. That is why we watch Arctic weather very carefully, and use those data to predict calf production in gray whales.

Photo: Wayne Perryman, NOAA SWFSC

Copyright Journey North (journeynorth.org). All Rights Reserved.