ABSTRACT: The puffer fish Takifugu niphobles migrates to spawn in the intertidal where it releases gametes at the water's edge at specific beaches. To examine proximate factor(s) influencing spawning site specificity of the puffer, 3 environmental characteristics [angle of inclination, bottom type (size of pebble/sand), and wave strength (relative decrease in weight of a plaster ball)] were investigated and compared between and within spawning sites. The puffer spawned at various types of beaches. Among 7 spawning sites in Japan, mean angles of inclination (6.68 to 11.30°), mean pebble sizes (4.47 to 44.79 mm), and mean wave strength (20.73 to 33.44%) differed significantly. Comparison of spawning and non-spawning areas at a single beach at Magarisaki, western Kyushu, showed that mean angle of inclination was significantly larger in spawning areas (8.84°) than in non-spawning areas (5.33°), but mean size of pebbles (30.04 and 32.51 mm) and mean wave strength (22.58 and 21.62% in the spawning and non-spawning areas, respectively) were not different. A discriminant analysis and stepwise multiple regression analysis indicated that only the angle of inclination significantly contributed (1) to discrimination between spawning and non-spawning areas, and (2) to variation in the frequency of spawning along the Magarisaki beach. The range of mean angles in the spawning areas of Magarisaki (5.88 to 10.77°) included most of the mean angles of the 7 spawning beaches in Japan. These results suggest that the puffer prefers a range of angles as the criterion used when selecting spawning sites. The preference for particular inclination angles appears to be for the benefit of adult spawners rather than the benefit of developing embryos or larvae: moderately inclined beaches are likely to provide an environment where adult puffers can easily gather, strand, and spawn.

KEY WORDS: Proximate and ultimate factor · Intertidal spawning · Site specificity · Environmental features · Inclination · Takifugu niphobles

Published in MEPS Vol. 147 (1997) on February 27
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1997