1.1 Background

This research project stemmed from the principal investigator’s (J. Leland) pioneering crustacean ageing research at Southern Cross University (see Leland et al., 2011), for which he was awarded the Department of Agriculture, Fisheries and Forestry 2013 Science and Innovation Award (Fisheries category). The associated Fisheries Research and Development Corporation (FRDC) funded grant initiated a one year research project into direct age-determination studies for two short-lived Australian crustaceans (ie the Mud Crab, Scylla serrata and Redclaw Crayfish, Cherax quadricarinatus). That project allowed J. Leland to refine his direct ageing protocols and resulted in one scientific publication (Leland et al., 2015) and an Honours thesis (Sarapuk, 2014) that demonstrated the methods applicability to short-lived subtropical decapods. During that time, co-investigator S. de Lestang was investigating the utility of direct methods for ageing Western Rock Lobster (Panulirus cygnus–see Rudd, 2013), while applying for FRDC funding (along with other co-investigators) to support further research. This project represents a combination of the two initiatives. Recognition of the value of developing direct methods for ageing crustaceans, while extending Australian leadership in this field has led to this collaborative effort. This project aligns with five FRDC Strategic Priority Areas: Program 1 (Environment), Program 2 (Industry), Program 3 (Communities), Program 4 (People) and Program 5 (Adoption).

From a fisheries management perspective, age information is an important biological variable, because of its importance for calculating recruitment, growth and mortality (Campana, 2001). Global recognition of this, combined with the requirements for effective sustainable management, has led to the development of methodologies that can be used to directly assign individual ages. Since the early fish ageing studies, direct ageing methodologies have expanded to include a diverse range of calcified structures that are present in invertebrate and vertebrate taxa, including gastropod statoliths (eg Chatzinikolaou and Richardson, 2007), polychaete mandibles (eg Leland, 2009), octopus stylets (eg Leporati and Hart, 2015), and the more commonly known fish otoliths (eg Piddocke et al., 2015a). Such structures are retained for life and record easily extractable age information. During the past few decades, finfish ageing studies have become somewhat routine, but analogous methods for crustaceans have been lacking (Leland et al., 2011; 2015).