The life-history of Cheilodactylus rubrolabiatus from south-western Australia and comparison of biological characteristics of the Cheilodactylidae and Latridae: support for an amalgamation of families

Cheilodactylus rubrolabiatus collected from the south and lower west coasts of Western Australia were used to investigate the influence of habitat and environmental conditions on the biology of this species. A lack of difference in the growth C. rubrolabiatus from cool south coast and warmer lower west coast waters in Western Australia and the greater maximum ages attained by fish on the latter coast, both run contrary to premises of the metabolic theory of ecology (MTE). Although the greater size (L₅₀) and age (A₅₀) at maturity of C. rubrolabiatus on the south coast is consistent with MTE, this may reflect higher densities of fish on discontinuous shoreline rocky reefs on this coast and thus the need for fish, particularly males, to attain a larger size to successfully defend habitat and mates during spawning. Members of the closely related Cheiodactylidae and Latridae vary in maximum fork length (L_Fmax 280–950 mm) and age (19–97 years) and display a range of growth patterns. While the L₅₀ of cheilodactylid and latrid species increased with increasing asymptotic lengths (L_∞), their maximum ages did not necessary reflect the A₅₀ (i.e., mature early, but live long). The M (natural mortality): k (von Bertalanffy growth parameter) ratios indicate that Cheilodactylus and Nemadactylus species exhibit a type II life-history strategy, typified by initial rapid growth, L₅₀ close to their L_∞ and little or no growth during an extended adult phase. A lack of distinct difference in the biological characteristics of the Cheilodactylidae and latrids may assist in resolving uncertainty regarding the taxonomy of these families.