Effects of fish age versus size on the development of whirling disease in rainbow trout

Diseases of Aquatic Organisms

Alexander V. Zale¹  Mark Nelson¹  Eileen K. N. Ryce¹  Elizabeth MacConnell¹ 

关键词: Myxobolus cerebralis;    Whirling disease;    Resistance;    Age;    Size;    Rainbow trout;   

DOI  :  10.3354/dao063069

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: We examined the effects of both fish age and size on the development of resistance to whirling disease in Erwin strain rainbow trout. Previously, we demonstrated that juvenile rainbow trout became resistant to development of the disease whenfirst exposed to triactinomyxons of the parasite Myxobolus cerebralis at about 9 wk post-hatch when raised at 12°C, but ages and sizes of fish used in that experiment were confounded (Ryce EKN, Zale AV, MacConnell E [2004] Dis Aquat Org59:225–233). In this study, rainbow trout of the same age and different sizes, and the same size and different ages, were exposed to the parasite to distinguish the influences of age and size. Fish were reared at 3 different water temperatures priorto exposure to produce groups with different growth rates and were exposed to the parasite at 7 or 9 wk post-hatch. Disease severity was affected by both age and size at first exposure, but the effects were not independent. An increase in fork length from36 to 40 mm among fish exposed at 7 wk post-hatch did not confer increased resistance, but the same increase in size at 9 wk post-hatch did. Similarly, an increase in age from 7 to 9 wk post-hatch among fish exposed at 36 mm fork length did not conferincreased resistance, but the same increase in age at 40 mm did. Rainbow trout must be both 9 wk post-hatch or older and at least 40 mm in fork length at time of exposure to exhibit enhanced resistance to whirling disease. Resistance to disease was notassociated with the level of skeletal ossification.

【 授权许可】

Unknown