The
effects of hydropeaking and intra- and interspecific competition on the growth
performance (growth in length, mass and lipid content) of juvenile Atlantic
salmon Salmo salar and brown trout Salmo trutta were studied in six
experimental channels (three experiencing hydropeaking and three controls with
a stable discharge of water). Changes in the water-covered area in the
hydropeaking channels were small to avoid fish stranding. Each channel was
divided into three similar-sized sections and stocked with either low or high
density of Atlantic salmon, or a mix of Atlantic salmon and brown trout, with
the density of the latter equalling the high-density treatment of Atlantic
salmon. A marked effect of competition was visible as salmon in the low-density
treatment were significantly larger (27-33%) and had a higher mass (30-38%)
than salmon in both the high-density salmon treatment and the high-density
salmon and trout treatment. Hydropeaking had only minor and insignificant
effects on the growth performance: overall final length, mass and body lipid
content in the salmon experiencing hydropeaking differed by -9%, -7% and +2%
compared with controls. Furthermore, there was no indication that the
competitive regime influenced hydropeaking effects. The increase in both intra-
and interspecific competition among the juvenile salmon had a pronounced and
significant effect on growth. Our study adds to the growing evidence that
energetic consequences of hydropeaking are likely to be small for Atlantic
salmon and that stress and mortality associated with stranding represent the
main source of population impact
Takaisin
The
effects of hydropeaking and intra- and interspecific competition on the growth
performance (growth in length, mass and lipid content) of juvenile Atlantic
salmon Salmo salar and brown trout Salmo trutta were studied in six
experimental channels (three experiencing hydropeaking and three controls with
a stable discharge of water). Changes in the water-covered area in the
hydropeaking channels were small to avoid fish stranding. Each channel was
divided into three similar-sized sections and stocked with either low or high
density of Atlantic salmon, or a mix of Atlantic salmon and brown trout, with
the density of the latter equalling the high-density treatment of Atlantic
salmon. A marked effect of competition was visible as salmon in the low-density
treatment were significantly larger (27-33%) and had a higher mass (30-38%)
than salmon in both the high-density salmon treatment and the high-density
salmon and trout treatment. Hydropeaking had only minor and insignificant
effects on the growth performance: overall final length, mass and body lipid
content in the salmon experiencing hydropeaking differed by -9%, -7% and +2%
compared with controls. Furthermore, there was no indication that the
competitive regime influenced hydropeaking effects. The increase in both intra-
and interspecific competition among the juvenile salmon had a pronounced and
significant effect on growth. Our study adds to the growing evidence that
energetic consequences of hydropeaking are likely to be small for Atlantic
salmon and that stress and mortality associated with stranding represent the
main source of population impact