A hydraulic study of salmon egg incubation baskets

Abstract

Atlantic Salmon egg incubation baskets are used to evaluate Atlantic Salmon egg survival rates in the natural streams and rivers in which they spawn. The survival data is gathered by placing a known number of Atlantic Salmon eggs within an incubation basket, placing the basket within a stream bed, and recording the number of hatched salmon caught within the emergence trap. Over time this data produces trends as to the heath of Atlantic Salmon as a whole, or in a particular stream or river. Survival rate data which has been collected for Atlantic Salmon populations through the use of incubation baskets has been very erratic. This maybe due to local variations in salmon survival or it maybe due to the incubation basket not adequately recreating the conditions for which the Atlantic Salmon require to survive. Therefore the goal of this project is to assess the hydraulic conditions within the salmon egg incubation basket and assess weather it adequately recreates natural conditions. The incubation basket itself is ~45cm long and ~12cm in diameter. It is made of ABS pipe which has been capped at both ends and has had 3 to 4 windows cut in the sides. In place of the windows, a 1mm mesh has been glued. The Atlantic Salmon eggs are placed in the centre of sieved gravel within the screened area of the incubation baskets. The incubation basket is then burred in the river's bed at the downstream edge of a river pool. The incubation basket remains there until the following spring when an emergence trap is placed on the top of the incubation basket, extending into the river. The hatched salmon swim into the emergence trap and are counted. This enables the a survival rate to be calculated.