No differences in egg buoyancy and anti-freeze protein production in genetically divergent subpopulations of Gulf of Maine Atlantic Cod (Gadus morhua)


Locally-adapted subpopulations of Atlantic cod are found in both the northwest and northeast Atlantic and exhibit differences in morphology, behavior and physiological characteristics. We conducted experiments to determine if demonstrable differences were evident in egg buoyancy and antifreeze glycoprotein production between captive populations of genetically divergent winter and spring-spawning cod from the Gulf of Maine. Fertilized eggs (<24 h post-spawning) were collected from both populations on 3 dates and transferred to 3 controlled-temperature rooms (5, 10, and 12 degrees C). Egg buoyancy was determined in triplicate samples, at each temperature, in seawater ranging from 28 to 35 ppt with 0.5 ppt increments. No significant differences in mean neutral buoyancy (similar to 1.024 g/mL) were found between stocks or treatment temperatures. Antifreeze glycoprotein (AFGP) production was examined in captive-bred cod juveniles (13-24 cm) from both populations held at 0 degrees C for periods ranging from 20 to 35 days. AFGP were first produced on day 30, although no differences were found in AFGP production in either population. Our results do not support the hypothesis that physiological differences in egg buoyancy and anti-freeze protein product exist between these two cod populations. The similarity in expression of these traits may reflect the high level of nutrition that both broodstock populations received, and the common juvenile size during cold-water exposure. (C) 2012 Elsevier B.V. All rights reserved.

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Fisheries Research



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© 2012 Elsevier B.V. All rights reserved.