How much does a marine mammal weigh?

Come out to the Seattle Aquarium and find out!

Many adult marine mammals gain and lose weight throughout the year depending on the water temperature, food availability and behavioral changes associated with breeding seasons. Here at the Seattle Aquarium we weigh our marine mammals at least twice a month in order to monitor their health.

Harbor Seals, April 11-13 – We’ll be weighing Barney, a 28 year old male harbor seal.
Guess Barney's weight here!

Harbor seals are the most abundant marine mammal living in Puget Sound and it’s almost impossible to tell a male from a female just by looking at them. The two male harbor seals at the aquarium usually weigh the most during the winter and lose some weight in the summer as the water temperature increases.

Fur Seals, April 25-27 – We’ll be weighing Commander, an 10 year old subadult male Northern fur seal.  
Guess Commander's weight here!

Male northern fur seals can weigh 5-6 times as much as their female counterparts! A female may only gain and lose 10-20 pounds throughout the year, while adult males can gain and lose over 250 pounds in one year! During the early summer, northern fur seals return to islands in the North Pacific to breed. Males come ashore to defend territories with the largest and strongest males attracting the most females into their harem.