Growth rate of two diverse populations of American oysters, Crassostrea virginica, and their reciprocal crosses

ABSTRACTS OF POSTER PAPERS

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Growth rate of two diverse populations of American oysters, Crassostrea uirginica, and their reciprocal crosses R.O. HAW’ES, K. SCULLY and H. HIDU tiniuersity

of Maine,

Orono, ME (U.S.A.)

ABSTRACT The Maine Agricultural Experiment Station has embarked on a long-term program to improve growth rate and reduce variability in the American oyster by evaluating various pure-line and cross-line combinations in the Damariscotta (ME) River estuary. Results from the initial matings between two diverse populations and their reciprocal crosses are reported. Stocks utilized were a commercial non-selected line (F) from Long Island Sound and the MSX disease resistant stock (D) developed at Rutgers (NJ) University. All animals were spawned in April 1986, placed at three estuarine sites in June, returned to a common system of ambient sea-water in November and again placed at the test sites in May 1987. At 7 months of age and at 18 months of age significant differences were seen between growth rates, with F x F animals being larger at all sites. The DXD animals were always significantly smaller than either of the crosses (Fd XD!? or D d x F $! ). The two cross-line combinations were generally not significantly different from one another. There was a significant site effect, with animals being longer at the warmer, less saline sites. Animals from the cross-line matings have been returned to Rutgers University to be evaluated for resistance to MSX.

Production of all-female carp and its applications in fish cultivation

WU CHINGJIANG. Institute

CHEN RONCDE.

of Hydrobiology,

Academia

YE YUZHEN AND HUANC WENYU

Sinica.

Wuhan (China)

ABSTRACT Production of ail-female carp is advantageous to fish cultivation, since female carp comes to maturity 1 year later than male and grows 20% faster than male in the first and second culture years. Female carp is presumed to be homogametic for sex determination(XX). The gynogenetic offspring which were employed for artificial sex reversal are all fernale( The phenotypic male(XX) was crossed with normal female carp(X?<) and all-female offspring were obtained. The fingerlings of all-female carp were cultivated in the adult pond and after 5 months the mean individual weight reached 0.6 kg and high fresh quality was achieved.

Study of clones of commercial fish

XIA DEQUAN, Freshwater (China)

LIU AIZHU, WU TINCTING

Fisheries

Research

Center,

Chinese

and SUN YU Academy

of Fisheries

Science,

Wuxi, Jiangsu