How do you study deep-sea fish?
Studying animals in their natural environment is difficult
enough but when the animal you are interested in lives deep
at the bottom of the sea under really high pressure AND with
no light, it makes it particularly challenging! So read further
to discover how the staff at Oceanlab do it….
Nicola uses a digital camera that can work down to depths of
6000 m - the length of 50 football pitches! The camera is baited
with mackerel, a particularly smelly fish, and the smell of the
bait attracts scavenging fish - fish that will basically eat
anything! The cameras takes pictures once every minute, and the
pictures allow Nicola to get lots of information including which
fish come to the bait, how long they stay, how many there are,
and their size.
The cameras are mounted onto special metal frames called “landers”.
The landers have floats but are weighted with scrap metal making
them sink to the seafloor. Once the camera has finished taking
pictures we send a sound signal from the ship which makes the
lander drop the weight. The lander then floats to the surface
where we can get it back onto the ship and downlaod the pictures.
The landers carry the camera (A) as well as other equipment
which measure how fast the current is moving, and in which direction,
and it also measures how salty the sea is (salinity) (B). The
lander also carries a flash (C) and a battery (D) for the camera,
and 2 releases which drop the weight when they receive the signal
from the ship (E). The bait is under the camera on top of the
weight with a ruler (F).
Once Nicola gets back to lab she can go through all the pictures
one by one identifying the fish, measuring and counting them.
Nicola never knows what she’s going to come across in the
next picture, and often there are big surprises like huge sharks
and really weird fish!
Listen
to the SCIENCE SNAP from Wed 16th March
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the Expert
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