Relationship between cannibalism and increase of metabolic activity during transitional stage from larvae to juveniles in teleosts

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 13660184
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: General fisheries
• Research Institution: Kyushu University
• Principal Investigator: OIKAWA Shin Kyushu University, Faculty of Agriculture, Associate Professor, 大学院・農学研究院, 助教授 (10175234)
• Project Period (FY): 2001 – 2003
• Keywords: tiger puffer / cannibalism / early life history / larva and juvenile / oxygen consumption / metabolic scaling / gill / pseudobranch

Research Abstract

The resting metabolic rate per unit body mass, M/W, of animals usually decreases with increasing body mass, being expressed by an allometric equation M/W=aW^<b-1>, where M is oxygen consumption of an animal, W body weight, and b-1<0. This phenomenon is well known interspecifically (among species) as well as interspecifically (within a species). However, the precise nature and the biological meaning of the ontogeny of metabolism have not been established in teleost fishes, because of very small and fragile nature of larvae and juveniles. Here we show that a puffer fish Takifugu rublipes has two phases during early life in which M/W increases with increasing W. By determining M/W and the frequency of cannibalism from 0.00068 g in wet W (just after hatch) to 3.0g (57 days old), we found that larvae reached to 0.01g increased M/W, and they began to attack and kill other fishes smaller than them, until fish smaller than 0.01g disappeared. The same events again occurred when juveniles reached to 0.1g. In the natural condition, these phenomena imply that individuals with growing ability more rapidly are assured of higher survival to reduce predatory risk. Gill and pseudobranch developments also explained the increase of M/W in the puffer fish.