Age determination of European lobsters (Homarus gammarus L.) by histological quantification of lipofuscin

During the past decade, quantification of the pigment lipofuscin in the olfactory lobe cell masses (OLCM) has been successfully used for age determination of crustaceans. The aim of the current study was to quantify the amount of lipofuscin in European lobsters (Homarus gammarus L.) of known age and to determine the accuracy of lipofuscin as an age predictor. Lipofuscin was quantified by confocal fluorescence microscopy and image analysis of histological sections. Our results showed that age and OLCM lipofuscin were closely and linearly related (r(2) = 0.88). Furthermore, in contrast to earlier studies, age was also closely, but nonlinearly, related to carapace length (r(2) = 0.78). Comparison of lipofuscin and carapace length as age predictors nevertheless showed that lipofuscin produced significantly more accurate estimates of age than carapace length. The relatively small difference in the precision of age estimation between lipofuscin and carapace length emphasises the importance of evaluating the relationship between age and carapace length/lipofuscin in studies of populations with variable environmental conditions or demographic processes. It is possible that age, in specific situations, could be satisfactorily predicted on basis of measurements of size.