Growth Of Japanese Flounder Research Articles

Genetic analysis of the main growth traits using random regression models in Japanese flounder (Paralichthys olivaceus )

For body weight (BW) and morphological traits measured repeatedly during growth in Japanese flounder, random regression models (RRMs) were constructed to genetically analyse growth curves and relative growth of morphological traits to BW or body length (BL). In the RRM of growth curves, genetic effects were optimally modelled using Legendre polynomials of two orders for six growth traits. Family and permanent environmental effects remained constant for morphological traits, whereas family effects changed linearly for BWs. During the measuring periods, the heritabilities of the traits increased with age and ranged from 0.256 to 0.843 for BW, 0.379 to 0.806 for body height, 0.338 to 0.773 for BL, 0.286 to 0.665 for head length, 0.159 to 0.708 for length of caudal fin and 0.335 to 0.774 for width of caudal peduncle. Genetic correlations for each trait decreased with increased lag in days of age. In the RRM of relative growth, all morphological traits analysed were significantly associated with BW and BL. The heritabilities for the allometries of morphological traits to BWs ranged from 0.251 to 0.755, whereas those to BLs ranged from 0.412 to 0.871. The majority of genetic correlations among these allometry scalings were negative. These estimated parameters can be utilized to not only guide the efficient selection of traits, but also to genetically regulate synchronous growth of body shape with BW in Japanese flounder.

Phenotypic and genetic parameter estimation of morphological traits related to axial body growth in Japanese flounder

A quantitative genetic analysis was undertaken to estimate the genetic parameters for morphological traits associated with axial growth in Japanese flounder. Three year classes (2009, 2010, 2011) that included a total of 47 full-sib families were produced. At 180 and 360 days of age, six morphological traits that included total length, body length, head length, trunk length, caudal peduncle length and caudal fin length were measured on 1,185–1,981 individuals per year class. Based on these traits observed, fifteen length ratio traits were constructed as well. The phenotypic analysis showed that coefficients of variation for the caudal peduncle length and the ratio of it to other length traits had large variation relative to the other traits analyzed. Genetic variations in axial growth of Japanese flounder were revealed by using a single-trait animal model with the fixed, additive genetic and full-sib family effects. All analyzed traits exhibited moderate to high heritabilities, ranging from 0.33 to 0.80. Heritability was higher at 180 days of age than at 360. The current results for estimating genetic parameters demonstrated that these traits related to axial growth could be improved with family breeding in Japanese flounder.

Stable cell-surface expression of Japanese flounder growth hormone in yeast Saccharomyces cerevisiae and growth-promoting effect on juvenile fish by oral administration

A cost-effective method for producing and using recombinant growth hormone (GH) has been developed. A cell-surface protein display system was constructed to produce recombinant Japanese flounder growth hormone (r-JfGH) in yeast Saccharomyces cerevisiae and the biological activity of expressed r-JfGH was evaluated by oral delivery to juvenile Japanese flounder. The expression vector pYD-E2, containing the JfGH gene, S. cerevisiae GAL1 promoter, and the S.cerevisiae URA3 gene downstream and upstream sequences, was designed and constructed to integrate the GH gene into the yeast genome and secrete r-JfGH stably on the surface of the yeast cell. Expression of r-JfGH was confirmed by flow cytometry until the 50th continuous generation of transgenic yeast strain y-E2, and over 0.98 μg r-JfGH per 1 mg total protein of y-E2 was estimated by an ELISA–RA assay. Growth of Japanese flounder was promoted significantly by the direct supplementation of freeze-dried transgenic yeast into the Japanese flounder juvenile feed at levels of 0.5 and 1%. The weight-specific growth rate and feed conversion ratio of the treated groups were 23.07 and 21.57% (0.5% feeding level) and 28.85 and 41.18% (1% feeding level), respectively, higher than that of the control group in a 7-week bioactivity study.

Present Status of Research and Production of Japanese Flounder, Paralichthys olivaceus, in Japan

ABSTRACT Aquaculture of Japanese flounder, Paralichthys olivaceus, started in the middle 1970s in Japan, and the commercial production became extensive in the early 1980s, with development of seedling production and farming techniques. Annual production in 1996 was 7,692 metric tons, ranked fourth among marine cultured finfish after yellow-tail, red sea bream, and coho salmon. Marine finfish aquaculture in Japan is mostly conducted in floating net cages; however, land-based culture tanks are the prevalent culture system for Japanese flounder. The tanks are circular, square, or octagonal and constructed of various materials: concrete, plastic and/or a combination of the two. Culture tanks are generally inside or covered with shade cloths. Sand-filtered sea water is continually supplied to each tank, with 12 to 24 exchanges daily. Three-gram fish are stocked in the culture tank and raised for 1 to 2 years until they grow to 500-1,000 g. Survival ranges from 60 to 80%. Sardines and sand lance, fresh or frozen, are mainly fed; however, use of moist or dry pellets are increasing recently because of the decline in catch of these fishes. Fingerlings are obtained from commercial hatcheries virtually year-round. The fish utilize almost no dietary carbohydrate as an energy source, and an increase of lipid in the diet did not improve the growth, although it did seem to produce a slight increase in protein efficiency ratio. Therefore, diet for Japanese flounder should contain high percentages of protein (fish meal). Finding alternative protein sources for fish meal in the diet has been researched, and the potential of defatted soybean, corn gluten, feather, meat, and meat bone meals have been examined. The optimum temperature for the growth is 20-25°C. Salinity range of 4.4 to 34.0 ppt did not affect the growth of Japanese flounder at 8 g initial body weight.

Effects of Temperature on the Growth of Japanese Flounder

Effects of Temperature on the Growth of Japanese Flounder