Abstract
Recent studies have reported that crustacean age determination is possible. We applied a direct ageing method (i.e. transverse cross sectioning of gastric ossicles) to a subtropical freshwater crayfish (Cherax quadricarinatus) sourced from an aquaculture population. Growth mark periodicity and the potential for chronological depositions were investigated by staining C. quadricarinatus with calcein and examining their ossicles a year later. Pterocardiac ossicles were superior to other ageing structures (i.e. other ossicles and eyestalks) and produced repeatable between-reader counts (87% were corroborated and 13% varied by ±1). C. quadricarinatus size-at-age data (for an aquaculture population) was described by a von Bertalanffy growth equation (L ∞ = 32 mm occipital carapace length; K = 0.64; t 0 = –0.18; R2 = 0.81). Ossicular growth marks did not correspond to moult history. The calcein stain was retained over an annual cycle comprising multiple moults, demonstrating that pterocardiac ossicles retain chronological information. The maximum age (3+) corroborated other indirectly-obtained longevity estimates for C. quadricarinatus. Multiple lines of evidence indicate that the growth marks in C. quadricarinatus ossicles are probably deposited annually during winter. The ability to extract age information from subtropical decapods provides substantial opportunities for advancing fisheries and conservation research globally, but further research is needed to provide a definitive validation and elucidate the mechanism governing the accrual of ossicular growth marks.
Highlights
Age information is important for calculating growth, mortality and productivity [1] and is important for both fisheries and conservation management [2,3]
Live C. quadricarinatus were sourced from a commercial aquaculture facility (Cherax Park Aquaculture Farm in Theebine, Queensland)–where they are reared in outdoor ponds–before
Direct Age Determination of C. quadricarinatus being transported to Southern Cross University (Lismore, New South Wales) on April 26 2013
Summary
Age information is important for calculating growth, mortality and productivity [1] and is important for both fisheries and conservation management [2,3]. Substantial research efforts have focused on developing direct age determination methodologies for aquatic species. Analyses of sequentially-deposited growth marks in calcified.
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