超声波估计鱼数量的研究

一、前言，日本渔业界对用探鱼仪原理来估算鱼数量的方法给予很大的希望，即用这个方法直接并且迅速地测定鱼数量。

Genetic Variation Among White Croaker Populations

To investigate the genetic structures and differentiation of different wild populations of white croaker （Pennahia argentara）, horizontal starch gel electrophoresis was performed on 133 individuals collected from five different locations in China and Japan. The eleven enzyme systems revealed 15 loci, of which eleven were polymorphic. The percentage ofpolymorphic loci of white croaker populations varied from 6.67% to 53.3.3%; the mean observed and expected heterozygosity ranged from 0.0033 to 0.0133 and 0.0032 to 0.0191, respectively. The expected heterozygosity revealed a low genetic variability for white croaker in comparison with other marine fishes. The genetic distances between populations ranged from 0.00005 to 0.00026. A weak differentiation was observed within each clade and between clades; and no significant differences in gene frequencies among populations were observed in white croaker. Among the five populations, three Chinese populations showed more genetic diversity than that in Japanese populations.

Application of quantitative PCR method in detection of Lymphocystis disease virus China (LCDV-cn) in Japanese flounder (Paralichthys olivaceus)

Lymphocystis disease causes serious economic losses in the fish farming industry. The causative agent of the disease is Lymphocystis disease virus China (LCDV-cn), which has a wide range of hosts. Based on competitive quantitative PCR technology, we established a method to quantify the LCDV-cn in tissue. Results demonstrate that the average amount of LCDV-cn in the peripheral blood of infected flounder with evident tumors is about 106virions/ml while the average amount in those flounder with no evident tumor but cultured with the flounder with evident tumor is about 104virions/ml. No virus was found in the negative samples of flounder.

Breeding and mass scale rearing of clownfish Amphiprion percula: feeding and rearing in brackishwater

Breeding and mass scale larval rearing of clownfish Amphiprion percula is very limited in brackishwater. We designed an indoor program of A. percula culture in brackishwater with a salinity of 24±1, during which the impacts of feed type, water temperature, and light intensity, on the efficiency of its reproduction, were revealed. The fish were accommodated along with sea anemones in fibre glass tanks to determine the influence of brooder diet on breeding efficiency. Higher reproductive efficiency [number of eggs laid （276±22.3 eggs）] was observed when fish were fed live Acetes sp. rather than clam （204±16.4 eggs）, trash fish （155±12 eggs） and formulated feed （110±10 eggs）. The spawning rate was increased during September and October （water temperature, 28.74±0.55℃） on average of 2.4 spawning per month; and low spawning rate was in January （water temperature, 24.55±0.45℃） on average of I spawning per month. Among three light intensities （100, 500, and 900 1x） set to evaluate larval survival rate, larvae showed the highest survival rate （65.5%） at 900 lx. The breeding method specifically in brackishwater developed in the present study is a new approach, will help the people from the regions of estuary and backwater to enhance their livelihood and it will lead to reduce the exploitation from the wild habitat.

Construction of a microsatellite-based genetic linkage map for half-smooth tongue sole Cynoglossus semilaevis

The half-smooth tongue sole Cynoglossus semilaevis is an important cultured marine fish and a promising model fish for the study of sex determination. Sex-specific genetic linkage maps of half-smooth tongue sole were developed with 567 mark- ers （565 microsatellite markers and two SCAR markers）. The parents and F1 progeny （92 individuals） were used as segregating populations. The female map was composed of 480 markers in 21 linkage groups, covering a total of 1388.1 cM, with an average interval 3.06 cM between markers. The male map consisted of 417 markers in 21 linkage groups, spanning 1480.9 cM, with an average interval of 3.75 cM. The female and male maps had 474 and 416 unique positions, respectively. The genome length of half-smooth tongue sole was estimated to be 1522.9 cM for females and 1649.1cM for males. Based on estimations of map length, the female and male maps covered 91.1% and 89.8% of the genome, respectively. Furthermore, two female-specific SCAR mark- ers, f-382 and f-783, were mapped on LG15f （linkage group 15 in female maps）. The present study presents a mid-density genetic linkage map for half-smooth tongue sole. These improved genetic linkage maps may facilitate systematic genome searches to identify quantitative trait loci （QTL）, such as disease resistance, growth and sex-related traits, and are very useful for marker-assisted selection breeding programs for economically important traits in half-smooth tongue sole [Current Zoology 59 （1）： 99-108, 2013].