Abstract:
Population biology of the marble octopus Octopus dollfusi in Prachuap Khiri Khan Province was studied. Samples were collected during January-December 202 from pair trawlers landed at Hua Hin Fishing Port. The estimated sex ratio (female to male) was significantly different from 1:1 (p<0.05). Sex ratio of female to total categorized by length class was low at 62.5 mm. and high at 92.5 mm. The correlative equation between mantle length (L) and weight (W) for male, female and combined were W = 0.001* L[superscript 2.6028], W = 0.0018* L[superscript 2.4546] and W = 0.0014* L[superscript 2.5182] respectively. Ratio of mature female to total female categorized by length class could be described by a logistic curve: P[subscript L] = 1/1+e[superscript 13.131-0.133*L]. Calculated average length at first maturation was 65.35 mm. The marble octopus spawns al year round, with two peaks: March to May and August to October. The relationship between fecundity (F[subscript c] and mantle length (L) could be described as F[subscript c] = 2.2586* L[superscript 1.8482]. The estimated asymptotic lengths (L[subscript infinity]) were 103.56 and 115.42 mm. while curvature parameters (K) were 1.145 and 1.6 yr[superscript -1] in male and female respectively. The total mortality coefficients (Z) were 3.3042 and 4.6482 yr[superscript -1] in male and female respectively. The natural mortality (M), fishing mortality (F) and exploitation rate in female were higher than those of the male.