Assessing current knowledge and future challenges of age determination, life span and growth performance in notothenioid fishes: a review

Age determination is an important tool in fishery research and management, providing key data for growth modelling and population dynamics. Knowledge of longevity and growth performance of fishes is especially important in defining their life history strategies. In this review we summarize all published data on the ageing of notothenioid fishes of the Southern Ocean, and evaluate factors influencing growth performance and longevity in a phylogenetic context. Most age estimates in notothenioids are based on otolith readings and application of the von Bertalanffy growth model to describe body growth throughout the life span. Growth performance and longevity both exhibit wide ranges between 3.5 and 5.5 and 7–52 years, respectively. However, growth performance is positively related to asymptotic fish size, whereas longevity is negatively related to the Brody growth rate coefficient. Lifestyle and latitudinal and depth distributions are the main factors influencing the life history traits of notothenioids. Growth performance significantly increases from benthic to pelagic species and declines toward higher latitudes. Conversely, longevity is higher in pelagic species and shows a positive trend with latitude and depth of occurrence. There is a trend toward an increase of both traits in the phylogenetically derived families, such as bathydraconids and channichthyids. Compared to Arctic fishes, notothenioids have similar values for growth performance and longevity. Currently the major gaps in our knowledge of age determination of notothenioids are the lack of validation of age estimates and the relatively low number of species studied. Future efforts have to provide more reliable and objective estimates of age through multiple comparisons among different laboratories and application of validation tools.