We had another great day in the field on Saturday. Dolphins, alligators, roseate spoonbills, and
other birds added to the experience of catching six more sharks! We caught one shark on each of the first
three longlines - 1 two-year old which we implanted a transmitter into to track
its movements, and 2 one-year-olds, one of which was a shark we caught in
August. The marks from collecting tissue samples were already incredibly well-healed! (see the picture below).
On the fourth set we had a lot more activity - while deploying the
longline I felt a tug on the line after putting out ~15 hooks and then an
immediate splash at the surface. When we
investigated what had caused the splashed we found a small neonate that was
born a within the last few months and we processed it before continuing to set the
line. Immediately after we resumed
setting the line, another little bull shark took the bait from the first hook
in the water, so we processed her and then resumed
setting the line. The sharks allowed us
to finish before any more bites, but when we pulled in the line another shark
of the same size was on a hook. Each of
the three sharks had recently closed umbilical scars (see picture) telling us
that they were born sometime during the summer and are probably still
developing their foraging (hunting) skills - it can take sharks time to learn how
to catch prey, and a free - or seemingly free - meal is easier than catching
a fish. We put
transmitters in each of the three newborns so we can track their movements to
see what areas of the estuary newborn sharks are using compared to older
individuals, and to investigate any individual variability in the movements of
sharks as they grow .
Hopefully our
luck continues to be good when we go out again in 2 weeks - I’ll let you know.
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| A flat calm day! |
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| Umbilical scar on a young shark. |
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