Marine Mammal Mania: harbor seal timeline

Just in time for four weekends of fun during our Marine Mammal Mania event, here are some fascinating details about the life cycle of the most ubiquitous (and, dare we say, most charming?) marine mammal in Puget Sound: the harbor seal! Plus tidbits about the Seattle Aquarium’s own Barney, Hogan and Q.

Marine Mammal Mania: harbor seal timeline

Mating (-10 months)

Harbor seals are usually conceived in September, when most mating occurs.

Implantation (-6.5 months)

When mating produces a fertilized egg, the egg stays in a state of limbo (or delayed implantation) for a couple months. It will not begin to develop into a harbor seal embryo until it implants in the mother’s uterus.

Birth (0)

In Puget Sound, most pups are born between late June and September.

Weaning (1 month)

Pups nurse for about one month before starting life on their own. Pups fast for the first 14–17 days after weaning and lose about 21 percent of their body weight. A rough start to life!

Sexual maturity (2–6 years)

Females mature when they are between 2 and 5 years old, and males mature when they are between 3 and 6 years old.


Marine Mammal Mania: harbor seal timeline

Hogan (2.5 years)

Hogan was born in June 2013 at Point Defiance Zoo & Aquarium.

Average longevity (8–10 years)

The average longevity for wild harbor seals is eight years for males and 10 years for females. But that average includes high mortality rates in the first few years. Wild harbor seals that survive those critical times can live into their 20s.


Marine Mammal Mania: harbor seal timeline

Q (16 years)

Q was born at Sea World San Diego.


Marine Mammal Mania: harbor seal timeline

Barney (30 years)

Barney was born right here at the Seattle Aquarium!

Oldest harbor seal? (48 years)

We don’t know for sure what the record is for the oldest harbor seal under human care but, as of 2014, a female at Cleveland was still going strong at the age of 48!

Interested in learning more about harbor seals before heading to the Aquarium for Marine Mammal Mania? Check out our harbor seal fact sheet!

Subscribe to the Seattle Aquarium Blog

Get news and updates from the blog delivered to your inbox