Alternatives to Sectioned Otoliths: The use of other Structures and Chemical Techniques to Estimate Age and Growth for Marine Vertebrates and Invertebrates

Abstract

In this chapter we describe structures, other than otoliths, and methods that are being used to estimate ages of fishes, sharks, molluscs, cubozoans, and echinoderms. Vertebrates and invertebrates are introduced and treated in separate sections and in each section we describe the structure, its preparation, interpretation and validation as a recorder of age. Our focus is on tropical, marine species but major gaps in the application of the various ageing techniques to this fauna means that we have described potential techniques from some temperate and freshwater studies. The utility of alternative structures to otoliths is illustrated and compared for the lutjanid sea perches, which predominate in published studies of age and growth of tropical fishes. Finally, we review the use of radioisotopes as a novel means of validating the age estimates of tropical animals and describe the technique of lipofuscin quantification to derive age estimates of invertebrates that lack hard body parts which can be used to estimate age.