Townsend Cromwell
Just in from the Ship
TC-99-04 Lobster TaggingMarch 24-April 21, 1999
April
15, 1999 Lobster tagging operations continue
with trap haul-back in the mornings and resetting the traps in the afternoon.
On the evenings of the 13th and 15th, we bottom fished for the elusive onaga
(Hawaiian red snapper) juveniles. On the evening of the 14th, we were in
transit to a bottom fishing site when some of the crew noticed rope trailing
from one of the props of the ship. So we anchored up, shut down the engines
and we divers began to suit up. The water was extremely clear and from the surface, we could make out the sea bottom 105 ft (32 meters) below. The three of us made our way back to the ship's props and found the port (left side) prop had become entangled in some old trawl line that must have been floating on the surface. It took us only a few minutes to disentangle it and have it hauled aboard ship for proper disposal. As we had plenty of air remaining, we agreed to descend to the bottom for a quick look before returning to the ship. It took us only a minute or two to reach the bottom and were promptly visited by a 6 foot (2 meter) long Galapagos shark. Galapagos sharks, their smaller cousins the gray reef shark, and Uluas (below, left), are among the top predators in the reef ecosystem and usually prove to be very curious about anything new that enters their domain. Gray reef sharks usually stay about 10 feet or so away from divers. Galapagos sharks however, seem to be comfortable approaching within 5 feet, which can prove to be a little unnerving. The animals are not interested in the divers as food items, but are checking out if our actions will result in spooking fish out of the reef that they can feed on. Video cameras placed on the backs of Hawaiian Monk Seals have captured footage of seals foraging by turning over rocks and corals in search of eels, octopus and reef fish. As the seal travels along, it is often followed by gray reef sharks and Ulua (large jacks) who quickly take advantage of any prey the seal frightens from hiding. One segment of video clearly shows a seal with a fish in its mouth and a gray reef shark continually trying to snatch the fish away. The seal eventually won out by twisting this way and that and pushing the shark away.
In no way am I trying to say that diving with sharks is not hazardous. Many seals have scars from shark bites and seal pups are hunted by Galapagos sharks. Divers collecting reef fish have had to cancel dives when the gray reef sharks in the area became too aggressive. We have canceled an entire day of diving due to the presence of a single tiger shark, which is the top predator in these reefs. The tiger shark does perceive seals, turtles and large animals as prey, so it is standard procedure to cancel dives if we notice one of them around. During the 9 minutes we were on the reef floor, we were approached by two Galapagos and one gray reef shark. The 6 footer approached fairly closely a number of times. All of the animals were well behaved and were merely "checking us out". When a shark approached, we stopped doing what ever it was we were doing and focused our attention on the animal. Sharks prefer to approach behind you and will generally approach closer if undetected. However turning to face them, often causes them to be more wary and stay further off. Swimming quickly away or shaking your hands at
them are definite "No No's". I don't feel fear when a shark approaches and actually find them amazingly graceful to watch. However, I do respect them and appreciate what they are capable of. Minimizing any actions which may attract sharks to a diver has always been good practice for us.
- For related information about lobster research, visit the Honolulu Laboratory's Kewalo Research Facility Lobster Research web pages.