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Off the Hook Answer Key

HOOK and BAIT TREATMENTS

Loggerhead Sea Turtle Catch by Hook and Bait Type
1. Using mackerel, the 18/0 Offset Circle Hook caught more loggerheads than the 20/0 Offset Circle Hook.

2. Using squid, the J Hook caught the most loggerheads and the 18/0 Straight Circle Hook caught the fewest.

3. Compared to the J hook baited with squid, the 18/0 Straight Circle Hook baited with squid caught about 65% fewer turtles, the 18/0 Offset Circle Hook baited with mackerel caught about 90% fewer turtles, and the 20/0 Offset Circle Hook baited with mackerel caught about 91% fewer turtles.

4. The 20/0 Offset Circle Hook baited with mackerel caught the fewest loggerhead turtles.

Leatherback Sea Turtle Catch by Hook and Bait Type
1. Using mackerel, the 18/0 Offset Circle Hook caught more leatherbacks than the 20/0 Offset Circle Hook.

2. Using squid, the J Hook caught the most leatherbacks and the 18/0 Straight Circle Hook caught the fewest.

3. Compared to the J Hook baited with squid, the 18/0 Straight Circle Hook baited with squid caught about 90% fewer turtles, the 18/0 Offset Circle Hook baited with mackerel caught about 58% fewer turtles, and the 20/0 Offset Circle Hook caught about 63% fewer turtles.

4. The 18/0 Straight Circle Hook baited with squid caught the fewest leatherbacks.

Swordfish Catch by Hook and Bait Type

1. Using mackerel, the 18/0 Offset Circle Hook caught more swordfish than the 20/0 Offset Circle Hook.

2. Using squid, the J Hook caught more swordfish than the 18/0 Straight Circle Hook.

3. Compared to the J Hook baited with squid, the 18/0 Straight Circle Hook baited with squid caught about 29% fewer swordfish, the 18/0 Offset Circle Hook baited with mackerel caught about 14% more swordfish, and the 20/0 Offset Circle Hook caught about 9% more swordfish.

4. The 18/0 Offset Circle Hook baited with mackerel caught the most swordfish.

TEMPERATURE

Loggerhead Catch by Temperature
1. Most of the loggerheads were caught in waters between 70-76 degrees F.

Leatherback Catch by Temperature
1. Most of the leatherbacks were caught in waters between 66-70 degrees F.

Average Swordfish Weight by Temperature and Hook/Bait Type
1. Most of the swordfish were caught in waters between 54-65 degrees F.

ANSWERS TO SUMMARY QUESTIONS

1. The 20/0 Offset Circle Hook with mackerel would best minimize the number of both loggerhead and leatherback sea turtles caught. This would be the second choice of swordfish fishermen.

2. The 18/0 Offset Circle Hook with mackerel would be the first choice of swordfish fishermen. The 18/0 Offset Circle Hook with mackerel results in approximately 0.15 turtles caught per 1000 hooks (0.04 loggerheads and 0.11 leatherbacks). The 20/0 Offset Circle Hook with mackerel results in approximately 0.105 turtles caught per 1000 hooks (0.035 loggerheads and 0.07 leatherbacks). This is a negligible difference.

3. The best temperature range for maximizing swordfish catch and minimizing turtle catch is 54-65 degrees F.

4. Swordfish fishermen can use the information from this study to minimize turtle bycatch while simultaneously maximizing swordfish catch. This can be done by switching from the J Hook baited with squid to the 18/0 Offset Circle Hook baited with mackerel, and by fishing in water temperatures ranging between 54 and 65 degrees F. Without the study, the fishermen may not have been aware that they could have a positive impact on reducing turtle bycatch, with relatively little compromise on their part.

5. If circle hooks are more costly than J hooks, regulatory agencies could cover enough of the cost to price them lower than J hooks and make them attractive to fishermen.

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Virginia Sea Grant Marine Advisory Program
Virginia Institute of Marine Science
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