Lake sturgeon growth and longevity from capture-mark-recapture data

Effective fishery management policy depends on accurate life-history data,
particularly for harvested species. Longevity is a core life-history trait
that is directly related to annual survival and lifetime reproductive
potential, but fish longevity is generally not well documented,
particularly for long-lived species. We used capture–mark–recapture data
spanning 44 years as an alternative method to estimate sex-specific adult
lake sturgeon (Acipenser fulvescens) average annual growth and longevity
for five populations in the Laurentian Great Lakes. We determined
individual fish average annual growth and fit population and sex-specific
exponential lines for average annual growth as a function of fish length
at initial capture. We used the exponential equations to estimate age for
180 cm fork length (FL) female and 160 cm FL male lake sturgeon from each
population by sequential subtraction of annual growth increments and
assuming age at onset of sexual maturity of 24 and 15 years for females
and males, respectively. Average annual growth estimates varied between
sexes and among populations and ranged from 0.26 to 1.15 cm year−1.
Estimated ages also varied among populations. Age estimated for a 160 cm
FL male lake sturgeon across the five populations ranged from 90 to
279 years. Age for a 180 cm FL female across populations ranged from 99 to
427 years. Our data suggest lake sturgeons live much longer than currently
believed. High longevity and inferentially higher adult survival have
important implications for sturgeons in general and support conservative
harvest regulations for lake sturgeon fisheries.