Age, growth and mortality of Gymnocranius audleyi (Pisces: Lethrinidae)

摘要

Age, growth and mortality of Gymnocranius audleyi (Pisces: Lethrinidae) from the central Great Barrier Reef (GBR), Australia were investigated. Age was determined by analyzing annuli in whole and sectioned otoliths (sagittae). Rings have not yet been validated as annuli for this species but for other lethrinids, as well as lutjanids and serranids on the GBR they were. The oldest fish in the sample (n = 107) was estimated to be 13 years of age. A high variability in size at age was observed. Both whole and sectioned otoliths and left and right otoliths were found to provide similar age estimates. Age estimates correlated with otolith weights better than with fork-length (FL), standardlength (SL) or total fish weight (TW). Fitted yon Bertalanffy growth functions (VBGF) gave growth (FL) parameter estimates (+- S.E.) of L_(inf)= 282 +- 9 mm; K = 0.557 +- 0.100: and t_o = 0.651 +- 0.388. The growth Performance index was #PHI#' = 4.648 +- 0.388 (S.E.)(for FL). Although all growth estimates were within ranges published for other lethrinids, G. audleyi appears to be a relatively fast-growing species. The total instantaneous rate of mortality (Z) was estimated as 0.583 +- 0.390 (S.E.). This study provides a basis for future management of the exploitation of this species on the GBR.