Effects of release strategy, CPUE and temperature on the total length at recapture of hatchery-produced ocellate puffer Takifugu rubripes in Ariake Sound

Abstract

  This study was conducted to examine the effects of release time, release size, release site, quality of seeds, CPUE of young-of-the-year and water temperature of the habitat on the growth of hatchery-produced ocellate puffer Takifugu rubripes released in Ariake Sound. The effects of seven factors on the fluctuations of the total length at recapture on November 1 (Y) of 23 release groups of seeds released based on the data of mark-recapture experiments from 1991 to 1995 and from 2000 to 2002 were examined by multiple regression analysis. The factors were as follows: the date of release in July (X₁), total length at release (X₂), release site (X₃), CPUE (X₅) and average surface water temperature of the habitat in July and August (X₆) and in September and October (X₇). The relationship of total length to these factors was follows:
  Y=-1.14X₁+0.49X₂-6.03X₃+0.54X₅-2.60X₆+1.87X₇+211.69
The regression was significant at the 1% level. The calculated values of the total length follow the trend of fluctuations of the observed values. Thus, it is concluded that is necessary to release hatchery-produced ocellate puffer early in July and at a large size in Isahaya Bay and the innermost area of Ariake Sound to maximize the total length at recruitment.