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When certain types of fish are brought to
the surface after being hooked or trapped at
depth, they can sustain injury (barotrauma)
from the change in pressure. I witnessed
this myself a long time ago fishing for
rockfish off of the California coast - the
fish would come to the surface bloated by
the air that had expanded as it ascended.
Even if the fish would have been released,
it would have died. Our most recent trip
to the Dry Tortugas included some
researchers who wanted to tag Mutton Snapper
with an acoustic tag to be able to track
their movement. In previous years, they
tried capturing the fish at depth, bringing
them to the surface, and doing the surgery
to insert the tag on the surface. The
problem with this approach is what I
mentioned above - the fish are stressed by
the change in pressure and are likely to die
from the procedure or be eaten by a predator
in their weakened state. So, on this trip,
the challenge was to do the surgeries
underwater, at depths that the Mutton
Snapper call home. I was lucky enough to get
to participate in some of the surgeries as
well as video and photograph them. I did a
very impromptu interview with Mike Feeley,
the Principal Investigator on the project,
and included some snippets of that
conversation in the video. Unfortunately, I
still have very limited internet access so I
have to upload only a low-res copy of the
video for now.
Despite some of the challenges associated
with the procedure (like capturing only the
target species, keeping an eye out for any
sharks or goliath groupers who might want an
easy Mutton Snapper meal, and performing the
whole procedure at depths ranging from 95 to
123 feet) we were able to successfully tag 8
Muttons and 3 Groupers. I’m going to be very
interested to see the data from the
receivers to see how our little surgical
patients are faring.
Chris Parsons |
