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Gross and histological observations of ovarian development and related condition changes in American plaice
Author(s) -
Maddock D. M.,
Burton M. P. M.
Publication year - 1998
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1998.tb00454.x
Subject(s) - vitellogenesis , biology , gonadosomatic index , oocyte , ovary , development of the gonads , seasonal breeder , fishery , zoology , gonad , endocrinology , medicine , population , fecundity , embryo , sociology , demography
The largest increase in gonadosomatic index of American plaice Hippoglossoides platessoides occurred between January and February. Hepatosomatic index was lowest in the spawning season, suggesting cessation of feeding activity during spawning, but rose immediately in July when condition factor recovered from its low spawning level. Increases in white muscle water content during the spawning season suggests protein depletion. Conservation of some white muscle fibres is suspected, but no regular pattern in area conserved was found. Gonad development was advanced in December and in April some gonads were showing evidence of spawning. Ovaries from spawning females showed hydration patterns and histological detail consistent with batch or serial spawning strategy. Evidence of recent spawning activity, including the presence of postovulatory follicles, was found in ovaries that also contained oocytes undergoing exogenous vitellogenesis. Oocyte size frequency distributions show a gap in size between cortical alveoli and vitellogenic oocytes prior to spawning which does not exist during the spawning season. This may represent the ability of plaice to push oocytes through vitellogenesis from a previtellogenic condition during the spawning period. The increased white muscle moisture during June and July may reflect the use of muscle protein to bring oocytes through vitellogenesis for the current spawning season.