Study of clones of commercial fish

ABSTRACTS OF POSTER PAPERS

327

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

ABSTRACT Artificially induced fish gynogenesis is a special genetic and selective method for producing inbred lines or homozygous lines. Induced gynogenetic grass carp (Ctenopharyngodon idella) and silver carp (Hypophthalmichthys molitrix) were produced by use of ultraviolet rays for common carp sperm inactivation and cold shock for egg diploidization. Examination of serum esterases as genetic markers, using electrofocusing of thin-layer 5% polyacrylamide gels, demonstrated that the genetic material of induced gynogenetic grass carp and silver carp was from the maternal parent, and was not detected from the paternal parent. Sex reversal experiments were performed on 12-13-cm gynogenetic silver carp with lo-12 mg methyltestosterone released from silastic implants that were inserted in the fingerling. Changes of morphology and construction of the gonads resulted.

Viable nuclear-cytoplasmic hybrids are obtained by electrofusion

CHEN HONCXI,

LIU PEILIN,

YI YONGLAN

and LIU HANQIN

Institute of Hydrobiology, Academia Sinica, Wuhan (China)

ABSTRACT Nuclear-cytoplasmic hybrid fishes have been obtained from the combination of nucleus and cytoplasm between two intergeneric species of fresh-water teleosts using the technique of electric fusion, i.e. the combination of the nucleus of carp (Cyprinus carpio red variety) and the cytoplasm of crucian carp (Caroasius auratus red variety), and the combination of the nucleus of Paramisgurnus dabryanus 9 x Misgurnus anguillicaudatus d and the cytoplasm of loach (Misgurnus anguillicaudatus). Morphological characteristics of those hybrid fish that have been examined so far are similar to those of donor nucleus parental species. Some of the hybrid fish grow to normal adults.

Survival in the early fresh-water period in Atlantic salmon (S&no solar) and rainbow trout (S&no guirdneri): heritabilities for survival and genetic correlation between survival and growth

M. RYE’ and K.M. LILLEVIK’ ‘Institute of Aquaculture Research, P.O. Box 10. N-1432 AS-NLH (Norway) 2Felleskjopet Rogaland, N-4000 Stavanger (Norway)

ABSTRACT Heritabilities

for survival in five periods in the early fresh-water

phase and genetic correlations