NORTHERN FUR SEAL BIOLOGY
Life span and survival rates of males and females have been estimated from the age composition of seals collected for scientific research by the United States and Canada (1968 – 1974). The ages of seals collected was determined by counting the annual growth rings on the upper canine teeth.
Females are capable of producing a single pup yearly from age 5 – 7 to age 23 years.
After birth, females tend to have a lower mortality rate than males (many males die between birth and age 8 – 10 years).
The maximum life expectancy for a breeding female is 26 years old.
Males reach sexually maturity at 4 – 5 years old, but usually don’t breed until 10 years old.
Competition between males for breeding territories is intense, and only the largest males are successful in obtaining and defending territories.
Age and body measurement data show that male fur seals reach their maximum mass at age 8 – 11 years.
The annual mortality rate of territorial males (≥ 10 years old) is approximately 38% (mostly due to fighting and fasting during the breeding season), and the maximum life expectancy of a breeding male is 17 years old.
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