We estimated the growth of Jack mackerel (Trachurus murphyi) using increments of daily growth, otolith weight and annual ring reading in sagittal otoliths. The daily micro-increments were used to fit ring density to the otolith radius (n = 4481) and then to estimate the age of the individual in days. The parameters of the von Bertalannfy growth equation were: maximum theoretical fork length, FL∞ = 75 cm; individual growth coefficient, K = 0.16 year-1; theoretical age at which fish length is zero, t0= –0.19 years. The growth parameters of T. murphyi estimated using annual rings reading were: K = 0.10 year-1, FL∞ = 74.7 cm, t0 = –0.50 years. The growth parameters estimated using otolith weight were: K = 0.15 year-1, FL∞ = 75.0 cm, t0 = –0.48 years. The parameter K estimated with the daily micro-increments was similar to the K estimated using sagittal otolith weights. We constructed a size-age key for T. murphyi using otolith weight, OW (milligrams) as a variable was: OW= 0.0323*t-15.197 (r2= 0.68). We recommend using otolith weight to estimate age in T. murphyi due to this technique is statistically reliable, but also cheap and fast.
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