Hemoglobin type, egg buoyancy, and antifreeze glycoprotein production as mechanisms for adaptive variation in Gulf of Maine Atlantic cod (Gadus morhua)

• Main Author: Clapp, Amanda R
• Format: Text
• Language: unknown
• Published: University of New Hampshire Scholars' Repository 2012
• Subjects: Agriculture; Fisheries and Aquaculture; Biology; Physiology; Zoology; atlantic cod; Gadus morhua
• Online Access: https://scholars.unh.edu/thesis/729; https://scholars.unh.edu/cgi/viewcontent.cgi?article=1728&context=thesis

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.