Reference |
Niva, T. 1999. Relations between diet, growth, visceral lipid content and yield of the stocked brown trout in three small lakes in northern Finland. Ann. Zool. Fennici 36:103-120. |
Abstract |
Diet, growth, visceral fat accumulation and a consecutive yield of the stocked brown trout (Salmo trutta L.) (four age groups, initial weight range 29–373 g) were studied in three small Finnish lakes in 1991–1996. The average growth rate and visceral lipid content were significantly greater in lakes and years when the trout fed mainly on small fish, such as vendace (Coregonus albula L.), ninespine stickleback (Pungitius pungitius L.) and one-summer-old perch (Perca fluviatilis L.) than their insectivorous conspecifics. The stocked trout initially foraging unpreferred food items shifted rapidly to feed on small fish when their stocks became abundant. Piscivorous trout increased their visceral lipids prior to winter whereas in insectivorous fish these decreased gradually during the growth season which probably caused increased overwinter mortality. Therefore, relative yields were significantly higher for piscivorous than insectivorous trout. On the other hand, the largest trout at release showed the poorest performance irrespective of the quality of the foraging environment. |
Tag |
Coded Wire Tag (CWT) VI Alpha |
Objective |
Evaluate stocking programs |
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