摂餌量推定のための琵琶湖産魚類の標準代謝量

抄録

The standard metabolic rates of fishes were measured for fundamental data that are useful for the estimation of the minimum amount of food required and for the consideration of the production problems. Various sizes of 17 species of fishes living in Lake Biwa were selected and their oxygen consumption was measured. The apparatus employed was similar to Hall's experimental apparatus using the running water system. The results obtained showed that the relation between oxygen consumption (R) and body weight (W) could be expressed by the equation, well known in the field of respiration physiology, R=KW^b (b : weight exponent constant, K : metabolic level). By the least square method, the values of b for each species was determined. Eliminating the values b having large standard errors, the values of b ranged from 0.41 to 1,the mean of which was 0.68,this is very close to the value 2/3. It was concluded reasonable to adopt the value of 0.68 for all fishes except "YARITANAGO" (Acheilognathus lanceolata) since the assumption, that is, the value of b for each species of fishes is 0.68,was not rejected statistically but for "YARITANAGO" it was rejected. Then assuming the value of b as 0.68,the values of K were calculated from the same equation, which was termed K_c, and then the metabolic levels at 20℃ (K_20) were determined from the values of K_c by assuming Q_10=2.5,with the aim of comparison between the oxygen consumption of different species of fishes. Values of K_20 obtained from laboratory experiments in which the fishes were kept in starvation, were about 0.3 for many species. On the other hand, the values of K_20 obtained from field experiments in which the fishes supposed to be not starved were about 1.1 on avarage. In this case, the K_20 values of a few species, that is"NIZIMASU"(Salmo gairdnerii), "BIWAMASU"(Oncorhynchus rhodurus), "AYU" (Plecoglossus altivelis), "ISAZA" (Chaenogobius isaza), were especially higher (1.58-2.23). Except for the above four fishes, they were about 0.7 which was about twice as much as those obtained from laboratory experiments (used fishes kept in starvation).