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Life Aboard Ship, Dispatches From South of the "Roaring Forties"
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Tuesday, July 6, 2004
As you recall if you read Bulletin 16, we were due to arrive at Tristan da Cunha
shortly. We did arrive, but we have a small problem: we are unable to land or
collect the fish we came here to get! Tristan has no protected harbor; the anchorage
is offshore of the only town, Edinburgh, and when it is too rough, it's not possible
to land. This morning we were advised that the wind (almost 40 kts at the time)
made it impossible.
So, we steamed down the west side of the island until we reached Cave Point,
behind which there is a wind shadow where we thought we could work. We put
over our two inflatables and set fish traps and a long line in shallow water
(about 20-30 feet) to try to catch B. diacanthus. We caught a few fish in the
traps, but the long line came up with no fish and no bait. Unfortunately, the
trapped fish were not what we wanted. We caught a rockfish, the false jacopever
(Sebastes capensis) and a Tristan wrasse (Nelabrichthys ornatus) but no nototheniids.
That wasn't too surprising, considering that it's a small fish (shorter than
10 inches maximum length) and seems to live in tide pools and just below the
tide line in crevices. Where we were able to fish seemed to be boulders and
cobbles, probably not the species' preferred environment. We also tried fishing
with rod and reel, and that was quite successful for the species that dominates
(by weight) the fish fauna of the shelf (near shore) areas in the Tristan group
of three islands, the fivefinger (Acantholatris monodactylus). It is also the
most commonly used for food and bait. We could hardly get a line to the bottom
before hooking one. And, I can assure you that they really do taste good! Wednesday, July 7, 2004: This morning the weather is much the same, with the
added possibility of an approaching front that seems very likely to make the
surf even worse. We steamed up to Edinburgh and could see that the surf was
quite spectacular all around the anchorage, where swells coming from the northwest
collide directly with the lava cliffs to the north and south of the town. I
would guess that some of the white water was reaching between 50 and 100 feet
above the sea level. We sacrificed the remaining nototheniids several days
ago before the seawater temperature rose to levels that would kill the fish.
We need the B. diacanthus badly; for some of our researchers it is one of the
primary reasons why they came. We are considering arranging for Tristanians
to collect for us (for pay); these fish could probably be transferred by sending
in an inflatable one time only. It would be a very wet trip, but we think it
can be done. At least in that way we would have the specimens we came to get. The wind has dropped this afternoon and we are hoping to
be able to get ashore tomorrow. We have been in contact with the Fisheries
officer on
the island,
and he thinks that if nothing changes, we will be able to collect; he has
offered to meet us and drive us to the best locations. Stay tuned for the
next installment
to discover "did they ever get to the island?" and "did they
ever get the fish they wanted?"!
The Tristan wrasse is particularly interesting because it undergoes a sex
change during its life. Individuals start as females, but some change to males
at 16-17 cm length. These become territorial during the spawning season, defending
temporary territories of about 2 m diameter and enticing females to spawn if
they enter the territory. What determines whether an individual changes sex
is not understood.
Just one of many
five finger, Acantholatris monodactylus, caught off Tristan da Cunha.
In
the meantime, we have looked at the bottom around the other two islands here,
Inaccessible and Nightingale, to see whether we might be able to
collect near shore there but to no avail. We were rewarded by being
able to see both
of them this afternoon (this morning it was rainy and foggy) and I can
state categorically that neither of them looks "friendly". Inaccessible
merits its name: it is surrounded by cliffs of about 1000 feet in height;
and how Nightingale got its name, we haven't a clue, because it doesn't look
like "that kind of place"!
Anchorstock Point on Tristan. Barely visible on the lower slope are farm buildings, which give scale to the base of the island's volcanic center.
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