River Surveys Isle
of Man
During
a recent visit to the Isle of Man I went on a day out to assist with
a river survey on the island. For the past 12 years the department of
fisheries and agriculture (DEFRA) have been conducting surveys to
assess the abundance of fish in the rivers in order to give each
river a classification of quality.
Using
electro-fishing they sample the same 30m stretch of different rivers
each year. Catching, recording and returning any fish caught. By
conducting the surveys year after year they get an indication of the
health of the river while assess fish stocks.
Electro-fishing
sounds like a brutal way to catch fish but it has all been tested and
approved for use. Throughout the day it became more apparent how
necessary it was. Using a metal ring connected to a battery, electric
current is charged into the water this momentarily stuns the fish
while others using nets catch the fish, which are place in holding
buckets. The fish we were catching, mostly juvenile trout and salmon
and some eels, were often small, hidden under rocks and in fast
flowing water. Without the use of electricity it would be near
impossible to catch them, it was hard enough using electricity. The
fish are then identified and measure. A second pass is then made to
catch any fish missed on the first run. An equation is then used to
make an estimation on any fish missed on both runs. Finally the fish
are return to the river.
We
assess three rivers during the day and caught roughly a total of; 65
trout, 115 salmon and 35 eels.
No comments:
Post a Comment