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14.4 Goliath Grouper’s Research and Conservation in USA
14.4.1 Catching, Sampling and Tagging
Sampling the protected Atlantic Goliath Grouper requires non-lethal methods. We
have developed these methods in our research on the ecology and recovery of this
species in Florida since it was fully protected in 1990. To catch adults we use 20–0
circle hooks attached to 900 lb. test monofilament leader about 6–7 m long.
Monofilament leader is superior to stainless steel leader because monofilament will
abrade and break if the fish becomes entangled in the reef structure—cable will not
break causing extreme stress to the fish and potentially death. We use heavy swiveled longline clips at the upper end of the leader and connect the leader to a loop in
the lower end of a 30 m long hand line made of 1.0 cm diam braided handline.
Depending on the current velocity, we usually attach about 2.0 kg of lead weight to
the juncture between the handline and the monofilament leader. Large pieces of
dead bait or live bait are suitable.
Under some circumstances such as fishing on wrecks, we attach a polyball float
(#50) to the hand line to suspend the bait above the bottom. The float provides a
buffer to the impact of the initial strike exerted by a hooked fish and can keep the
fish out of the structure of the reef/wreck. To avoid extreme stress to the fish from
barotrauma we limit our depth of fishing to about 30 m.
After bringing the fish to the surface, we pull it on deck, then onto a 2.0 m long
stretcher, with a short swivel-handle gaff. We hook the gaff behind the lower jaw
through the thin membrane and pull the fish into the boat. The fish is then tied
down to the stretcher to keep it from thrashing about on deck—this eliminates the
possibility of injury to both the fish and the crew. A running seawater hose is inserted
into the fish’s mouth to irrigate the gills and the exposed eye is covered with a wet
towel to protect it from direct sunlight. We then vent the fish using a stainless steel
trocar (9.5 mm diam) & cannula which is designed for venting cows with bloat, but
it works well for venting Goliath Grouper. We puncture the fish with the trocar (with
the cannula slid over it) at a point just behind the tip of the pectoral fin (while the fin
is laid flat against the body) and just ventral to the midline—removal of a few scales
is necessary before penetrating through the skin. After puncturing the swimbladder,
the trocar is removed leaving the cannula inserted for about 30 s or until all the gas
is expelled.
While the vented fish is immobilized on the stretcher with seawater flushing the
gills, we sample and tag the fish. For aging the fish we excise fin rays 6 and 7 at their
base (or remove them at their articulation with their respective pterygiophores) from
the second dorsal fin. Fin rays are kept in labeled bags and put on ice until they can
be stored frozen for later processing. Stomach contents are collected by hand—we
insert a 15 cm diam, 30 cm long PVC tube into the mouth, then extend our arm
through the tube into the fish’s stomach to remove contents. We use several types of
tags: livestock ear tags, PIT tags (passive integrated transponders), and acoustic tags
(Vemco V16 s, 10-year battery). Ear tags are clipped into the base of the posterior
14 The Atlantic Goliath Grouper: Conservation Strategies for a Critically Endangered…
14.4 Goliath Grouper’s Research and Conservation in USA
14.4.1 Catching, Sampling and Tagging
Sampling the protected Atlantic Goliath Grouper requires non-lethal methods. We
have developed these methods in our research on the ecology and recovery of this
species in Florida since it was fully protected in 1990. To catch adults we use 20–0
circle hooks attached to 900 lb. test monofilament leader about 6–7 m long.
Monofilament leader is superior to stainless steel leader because monofilament will
abrade and break if the fish becomes entangled in the reef structure—cable will not
break causing extreme stress to the fish and potentially death. We use heavy swiveled longline clips at the upper end of the leader and connect the leader to a loop in
the lower end of a 30 m long hand line made of 1.0 cm diam braided handline.
Depending on the current velocity, we usually attach about 2.0 kg of lead weight to
the juncture between the handline and the monofilament leader. Large pieces of
dead bait or live bait are suitable.
Under some circumstances such as fishing on wrecks, we attach a polyball float
(#50) to the hand line to suspend the bait above the bottom. The float provides a
buffer to the impact of the initial strike exerted by a hooked fish and can keep the
fish out of the structure of the reef/wreck. To avoid extreme stress to the fish from
barotrauma we limit our depth of fishing to about 30 m.
After bringing the fish to the surface, we pull it on deck, then onto a 2.0 m long
stretcher, with a short swivel-handle gaff. We hook the gaff behind the lower jaw
through the thin membrane and pull the fish into the boat. The fish is then tied
down to the stretcher to keep it from thrashing about on deck—this eliminates the
possibility of injury to both the fish and the crew. A running seawater hose is inserted
into the fish’s mouth to irrigate the gills and the exposed eye is covered with a wet
towel to protect it from direct sunlight. We then vent the fish using a stainless steel
trocar (9.5 mm diam) & cannula which is designed for venting cows with bloat, but
it works well for venting Goliath Grouper. We puncture the fish with the trocar (with
the cannula slid over it) at a point just behind the tip of the pectoral fin (while the fin
is laid flat against the body) and just ventral to the midline—removal of a few scales
is necessary before penetrating through the skin. After puncturing the swimbladder,
the trocar is removed leaving the cannula inserted for about 30 s or until all the gas
is expelled.
While the vented fish is immobilized on the stretcher with seawater flushing the
gills, we sample and tag the fish. For aging the fish we excise fin rays 6 and 7 at their
base (or remove them at their articulation with their respective pterygiophores) from
the second dorsal fin. Fin rays are kept in labeled bags and put on ice until they can
be stored frozen for later processing. Stomach contents are collected by hand—we
insert a 15 cm diam, 30 cm long PVC tube into the mouth, then extend our arm
through the tube into the fish’s stomach to remove contents. We use several types of
tags: livestock ear tags, PIT tags (passive integrated transponders), and acoustic tags
(Vemco V16 s, 10-year battery). Ear tags are clipped into the base of the posterior
14 The Atlantic Goliath Grouper: Conservation Strategies for a Critically Endangered…