熊野灘におけるイサキの成長
1980 年 27 巻 1 号 p. 64-71
詳細
1980 年 27 巻 1 号 p. 64-71
The present report deals with age and growth estimations based on ring marks on scales for Parapristipoma trilineatum (Pomadasyidae).Materials used in this study consist of 1170 individuals ranging from 49 to 355.7 mm in fork length.They were taken by set net, hook and line and gill net from coastal areas of Kumano-nada during the period from March, 1978 to April, 1979.A number of scales were taken from a row beneath the lateral line of the left side of the fish just posterior to the tip of the pectoral fin, and a scale of regular shape among them was selected and used for measurement.
The results obtained are summarized as follows:
1) The relationships between the fork length (L in mm) and total length (TL in mm), standard length (SL in mm) and body weight (W in g) were shown by the following equations:
logTL=1.01logL+0.019
logSL=1.02logL-0.106
logW=3.25logL-5.388
2) Ring marks on scales were formed twice in a year, both in summer and in winter.Of these two ring marks, the ring mark formed in the period from January to February was used for the estimation of age and growth of the fish.The other ring was considered to be the spawning mark, because the ring mark was inconspicuous in immature specimens and the time of ring formation in mature specimens corresponded to the spawning season from June to July.
3) An anti-Lee phenomenon was observed in the mean value of each ring radius.-Phenomenon may be attributable to the growth of old tissue of scale.
4) The relationship between the fork length and scale radius (R in mm) was shown by the equation log L=0.881 log R+1.842.The fork lengths at the time of ring formation were calculated using the above equation.
5) The results obtained from the Walford's growth transformation method indicated that the plots of ln+1 against ln fall on a straight line, given by the equation ln+i= 0.779ln+78.3.
6) Since the time difference between spawning and ring formation on scales was about 0.5 year, the Bertalanffy's growth equation for full age (t) in fork length (Lt) and weight (Wt) was given as follows:
Lt=355 (1-e-0.249 (t+0.731) )
Wt=794 (1-e-0.249 (t+0.731) ) 3.25
7) There was no sex-associated difference in growth.
