Birds are easily disabled by stress, which often has adverse effects on their health, thus birds should be handled as little as possible to minimize stress. In the present study, the effects of the tranquilizer Diazepam against restraint stress were evaluated using the Japanese Quail Coturnix japonica. When restraint stress was applied to the birds by squeezing their cage, the plasma corticosterone (hormone which increases under stress) levels increased markedly, while no difference was observed in the birds that had only undergone blood sampling. Thus, the squeezed cage is a suitable instrument for examining restraint stress. Intramuscular injection of diazepam before restraint stress resulted in no significant increase in the corticosterone level. In contrast, the corticosterone level increased markedly when saline was administrered as a placebo. These findings demonstrate that the use of a tranquilizer is very effective in reducing stress, and that tranquilizers will be useful in the study of stress reduction or in the investigation of the mechanisms of stress in birds.

抄録全体を表示

In order to evaluate and to recover the gene pool of the threatened Clown Knifefish, listed in the red data book of Viet Nam, we applied an inducing hormone, LRH-A3+Dom at three different decisive rates of 70 mg, 100 mg, and 150 mg LRH-A3/kg for female fish at half of the decisive rates of those applied for male fish. In parallel, we also caught randomly ten Clown Knifefishes from four ponds and analyzed them using the SDS-PAGE electrophoretic protein method to evaluate their genetic diversity. Results showed that most of the electrophoretic proteins of the samples were similar to each other, suggesting that the gene pool of this species is very narrow and may decline seriously in the near future. Injecting the inducing hormone hormone at a rate of 150 mg LRH-A3/kg led to high rates (about 95%) of fertilization and hatching. Fortunately, we detected differently the genital papilla of mature males and females during the spawning season. Given the successful results of artificial propagation and the economic significance of this fish as food, this species may perhaps be encouraged to increase and so may be removed from the red data book in the near future.

抄録全体を表示

Four shrimp species (Penaeus merguiensis, P. monodon, Metapenaeus ensis, M. tenuipes) occur mainly in the estuary of the Mekong River, in mangrove forests along the seashores of the Mekong Delta. The SDS-PAGE method of protein analysis was applied to the structural protein of antenna in order to seek genetic diversity. Five traits were examined: phenotypic diversity (Ho), genetic diversity (H_EP), percentage of polymorphic individuals, percentage of polymorphic bands, and the sum of the effective number of alleles (SENA). Research revealed that M. tenuipes has the lowest level of diversity in all five traits, indicating that its population is declining dramatically. In addition, the genetic pool of the other three species in this region has decreased significantly as a consequence of extreme exploitation as a cash crop. The results of this research will be useful for these economically important shrimp species and for their conservation and breeding in the near future.

抄録全体を表示

The foraging ecology and acoustic behavior of the killer whale (Orcinus orca) was studied in Avacha Gulf, Kamchatka Peninsula in the Russian Far East from 1999 through 2003. Two main forms of foraging behavior were observed: the "carousel" type, when killer whales surround a school of fish and swim into the center one after another, and the "asynchronous diving" type, when a killer whale group forages within a determined area, either in a tight group or in subgroups of 2-5 animals. Killer whale groups contained from 1 to 49 animals (mean = 9.56), but the typical group size ranged from 6 to 10 animals. No examples of killer whale aggression or hunting behavior directed toward other marine mammals were witnessed. Kamchatkan killer whale groups proved to be highly vocal, producing calls, whistles, and echolocation sounds in different behavioral contexts. Call type repertoires defined for the seven groups within the study population showed that each of these groups shared at least one call type with another group, which by definition means that all these groups belong to the same acoustic clan and the same population. Killer whales observed during this study represent one population and have biological features (group size, foraging and acoustic behavior) similar to the northeast Pacific resident killer whale populations.

抄録全体を表示