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WHAT IS ELECTROFISHING ?
Scientists use electrofishing to survey fishes and monitor
the size of populations and determine the species in a
community. Whether using a boat or a backpack electroshocker,
the basic principle involves generating an electrical field in the
water to stun fish. When fish are stunned, they often times float
near the surface of the water and can be removed from the
electrical field.
How Do Fish Get Stunned?
When a fish swims into a weak electrical field, it may not be
affected at all. There is a threshold of electrical charge that must
be emitted into the water in order to affect the fish.
When the electrical charge in the water is sufficient to allow
transport of the charge across the nerve cells in the body, then
the fish's muscles will undergo involuntary contraction. The
contractions will lead to increased exercise of the muscle and a
build up of lactate in the blood stream. This process is very similar
to what happens to the muscles of a runner or a swimmer who
exerts a lot of exercise. The runner or swimmer may eventually
get a cramp in the muscle and cannot move it effectively. When
the fish cramps up, it floats to the surface and can be removed
from the electrical field. The process to stun a fish is usually 5 -
10 seconds.
Once the fish is removed from the electric field, the Tidal
Bass Survey team places the fish in a live well with good aeration.
The aeration and cool temperatures are essential in the live well
because the fish has an oxygen debt that needs to be paid. Like
a runner or swimmer, the lactate in the blood stream and
cramping must be treated with rest and good oxygen supply.
While this period of recovery may take a short time in humans,
