Date of Award
Program or Major
Master of Science
David L Berlinsky
Three physiological traits were examined to compare captive populations of winter- and spring-spawning cod from the Gulf of Maine, as differences in these traits have been observed in other locally-adapted subpopulations. Daily mean neutral buoyancy of hatchery-spawned eggs was observed at three temperatures (5, 10, and 12°C) and three photoperiods (15:9, 9:15, and 24:0 L: D) at 12°C. Body fluids of larvae held at 0°C for five days were tested for antifreeze glycoproteins (AFGPs) to determine the onset of AFGP production. Juveniles held at 0°C were bled between 20 and 35 days to determine induction time for AFGP production. Hemoglobin type was determined by isoelectric focusing of blood from hatchery-reared adults. No significant differences were found in mean neutral buoyancy (∼1.024 g/mL) or hemoglobin type (mostly HbI-1/2). No AFGPs were detected in larvae. AFGPs were first produced by juveniles on day 30, although no AFGP production differences were found between populations.
Clapp, Amanda R., "Hemoglobin type, egg buoyancy, and antifreeze glycoprotein production as mechanisms for adaptive variation in Gulf of Maine Atlantic cod (Gadus morhua)" (2012). Master's Theses and Capstones. 729.