Creation of artificial upwelling areas for brown trout, Salmo trutta, spawning in still water bodies

Abstract

Brown trout, Salmo trutta L., spawning sites were constructed by creating areas of artificial upwelling water, 252 ± 37mLm-2 min-1 (95% CL), through appropriately sized spawning gravel substrate in 3m2 vessels buried in the bottom of a 150-m2 pond. Natural spawning occurred in the vessels during autumn 2001-2004, with hatching and alevin swim up the following spring. In areas of upwelling, egg survival was 85-95%, while no live eggs were observed in areas without upwelling. In areas with upwelling, the maximum density of live eggs at the eyed stage was 570-1510 eggs m-2. In spring 2004 and 2005, the density of alevins was estimated at 322 (±187) m-2 and 567 (±217)m-2, respectively, in areas with upwelling water, compared with 35.2 ± 25.4m-2 in areas without upwelling water in 2004. © 2006 The Authors. Journal compilation © 2006 Blackwell Publishing Ltd.