Age, Growth and Mortality of the Goldlined Seabream Rhabdosargus sarba in Waters off Southwestern Taiwan

Age, growth and mortality of the goldlined seabream, Rhabdosargus sarba, were estimated based on 593 and 6516 specimens that were collected in waters off southwestern Taiwan from September 2015 to August 2016, and April 2015 to December 2017, respectively. The body weight (BW) and total length (TL) relationship (all data-pooled) was expressed as: BW = 0.01511 TL3.0346 (r2 = 0.95; n = 593). Growth rings (identified as opaque and translucent zones) were counted on 447 sectioned sagittal otoliths using a microscope under transmitted light and were counted up to 8 (42.0 cm TL) for both sexes. Edge analysis indicated that growth rings in otoliths were deposited once per year, and the opaque zone was formed in December. The von Bertanlanffy growth function (VBGF) best fit the observed length at age data for R. sarba. The growth parameters (±standard error) of VBGF for R. sarba (all data-pooled) were estimated as: L∞ = 53.94 ± 3.71 cm TL, k = 0.217 ± 0.033 yr−1, t0 = −0.182 ± 0.167 yr (n = 447). Total mortality estimated from a length converted catch curve was 0.655 yr−1, age-specific natural mortality and fishing mortality were estimated as 0.789–0.293 yr−1 and 0.109–0.365 yr−1, respectively. The exploitation rate was estimated to be 0.440.