Circumstances of energetic use of white muscle protein in two flatfish species, Hippoglossoides platessoides and Pleuronectes americanus: starvation, natural variation and reproductive demands on white muscle

• Main Author: Maddock, Dawn M.
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1997
• Subjects: Newfoundland
• Online Access: https://research.library.mun.ca/4134/; https://research.library.mun.ca/4134/1/Maddock_DawnM.pdf; https://research.library.mun.ca/4134/3/Maddock_DawnM.pdf

White muscle moisture was examined in two species of flatfish indigenous to Newfoundland waters, the winter flounder (Pleuronectes americanus) and American plaice (Hippoglossoides platessoides), in relation to seasonal cycles and experimentally induced energetic stress. Natural elevation of white muscle moisture observed during the spawning season in H. platessoides reflects protein usage and is probably due, in part, to energetic demands imposed by batch spawning. The observation of developing yolky oocytes coinciding with evidence of recent spawning suggests the potential to increase fecundity during the spawning season by recruitment of immature oocytes for release in the current season. This might require further depletion of white muscle protein resulting in the significantly higher muscle hydrations observed at this time. -- Experimental conditions which imposed energetic stress on H. platessoides as a result of high temperatures caused restricted gonad development if condition of the fish was less than 0.85 prior to setup and allowed maintenance of low white muscle moisture. Low condition fish which underwent reproductive development despite unfavourable conditions, experienced high muscle hydration and resorption of vitellogenic oocytes was evident upon termination. Those fish with high condition prior to setup developed their oocytes to a mature, vitellogenic state and maintained significantly lower muscle moisture than low condition fish which were in similar state of reproductive development at termination. -- Depletion of white muscle protein is a reversible process. After only four months of refeeding, a rebound in condition and lowered white muscle moisture was observed in winter flounder, P. americanus, in which low condition and high white muscle moisture had been induced by starvation. The ability to selectively use and rebuild white muscle suggests an energetic storage system which has been developed to deal with energetic demands the fish might face in the wild, including reproductive ...