1999 年 65 巻 3 号 p. 424-431
Relationship between year-class abundance of the oval squid Sepioteuthis lessoniana and selected environmental factors are examined using multiple linear regression analysis to predict landings. Landings from April to August, an index of spawning stock size, had no relationship (r=-0.123) with the landings during the subsequent September to December as a recruitment index. This implies that no relationship between spawning-stock and recruitment occurs in this species. Landings from September in a given year to the next August were employed as an index of the year-class abundance in the year (criterion variable, Y). Average monthly values of four environmental factors during the period from April to September which includes the spawning and hatching season and the early life period of this species were examined as explanatory variables: water temperature (X1) and salinity (X2) at 10m depth; and atmospheric pressure (X3) and rainfall (X4) measured in Tokushima City. The year-class abundance were expressed as Y=-329 7.4+37.OX1+79.9X2. From the multiple regression equation with environmental data from April to September, year-class landings are predictable. The year-class landings is closely related to the water temperature with salinity during April to September. High water temperatures and high salinities during this period are associated with successful recruitment.
