Data from: Growth and longevity of the endangered freshwater pearl mussel (Margaritifera margaritifera): Implications for conservation and management

Key life-history data, such as growth and age, are necessary to
effectively manage and conserve threatened freshwater mussel species.
Traditionally growth and age studies require large yet destructive sample
sizes covering all age classes. Such methods pose a risk to populations of
conservation concern, and therefore alternative methods that need only
limited sample sizes are necessitated to prevent further threats to such
populations. We applied retrospective shell growth at age
reconstructions to 98 critically endangered freshwater pearl mussel (FPM)
individuals from 34 populations across Finland and Sweden, enabling the
use of extremely small sample sizes (n = 1–6 per population). We compared
the performance of six different growth models with the reconstructed
size-at-age data across FPM juvenile (<20 years old) and adult life
stages. The growth reconstruction model showed reasonable skill
in reconstructing FPM growth patterns. The von Bertalanffy model was shown
to be a good general descriptor of growth for FPM, but it systematically
underestimated the asymptotic size. The power law model was the most
accurate in estimating juvenile growth (lowest deviances from the
size-at-age data). FPM showed great variability in longevity (Amax =
54–254 years) and growth constant k (0.018– 0.057 year-1). Our
results show that reasonable estimates of growth can be attained even when
sample sizes are extremely limited. The results can be further applied to
gain knowledge on the population’s age structure, size at maturation, and
recovery potential. The methodology is applicable to other freshwater
mussel species of conservation concern.