Large pelagic fishes such as blue sharks and swordfish although "cold blooded," appear to use heat acquired at the surface to remain warmer than the water at depth for many hours. Swordfish swim near the warm surface to feed at night, but move deep into cold water during the day. They appear to manipulate their body temperature by a thermal hysteresis in the muscle which cools slowly in deep cold waters, but rewarms rapidly upon return to warm surface waters. Blue sharks, which swim up and down hundreds of meters in continuous oscillations, may be obtaining the same thermal advantage. However, their continuous oscillations may be necessary because they are less effective in managing temperature than swordfish. Dr. Carey, who has pioneered research on this topic, will continue his investigations into the process of behavioral thermoregulation in these fish. He will combine telemetered information with shipboard measurements of water temperature vs. depth, light and echosounder records to investigate the factors the fish respond to.
