Understanding and Managing
CARRYING
CAPACITY
We need to think about the whole catchment. Problems in one part are likely
to affect other parts – e.g. poor habitat or obstacles in the upland
tributaries or pollution in the estuary.
And we need to understand that rivers can only support a limited number of fish. A 5 acre field can only support 20 sheep, a square meter in a garden will only grow 3 potato plants. If you put in more they all may suffer.
The
Girnock Burn fish traps at summer flow
For the last 35 years the salmon entering the Girnock Burn, a tributary of the Aberdeenshire Dee, and the smolts leaving have been counted. The Burn requires 40 hen salmon to seed it. Whether 40 or 140 hen salmon spawn the burn produces the same number of smolts. There is not food or habitat available for more.
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