Development of a DNA-based aging technique for use in fisheries assessments
Rosie Godwin, Damien Broderick, Vivek Mitter and Raewyn Street, Ian Brown, John Russell, Brian Paterson and Phil Gaffney, Steve Montgomery, Melissa Brown and Stewart Frusher.
Supported by funding from the Fisheries Research and Development Corporation (FRDC) on behalf of the Australian Government ( 2007/033)
The ages of individual animals in the wild are not always obvious. For most species, once juvenile stages are complete, there are no outward signs of age. Some animals (e.g. fish) continue to grow with age, but size is influenced by environmental conditions. Hard parts (e.g. teeth and bones) can indicate age but accuracy is low and the method is usually destructive. Species without hard parts (e.g. beche-de-mer) or whose hard parts are shed (e.g. crustaceans) cannot be easily aged.
One method that has been applied to age determination in the past is telomere length. Telomeres are units of repeated DNA at the end of chromosomes complexed with specialist proteins. They generally decrease in number at each mitotic division in somatic cells. A DNA-based method of estimating age has been the topic of research in project 2007/033. The DNA method has the potential to be (1) rapid and inexpensive, (2) performed on biopsy tissue without sacrificing the animal and (3) applied across broad size range. The project compared telomere lengths and rates of attrition of telomeres with age in a range of crustacean and molluscan species. Interestingly, there was little if any relationship for crustacean species, while the two molluscan species (abalone and oysters) showed declining telomere lengths with age (oysters) or shell size (abalone).