不同放养密度和混养石莼对牙鲆鱼种生长的影响

INFLUENCE OF STOCKING DENSITY AND POLYCULTURE WITH(Ulva pertusavar)ON GROWTH OF JAPANESE FLOUNDER (Paralichthys olivaceus) JUVENILES

牙鲆的放养密度以所放养鱼腹面表面积之和占养殖池底面积的百分数 ( % )表示。在直径为27cm、容积为40L的塑料桶中放置网箱 ,按网箱底面积48 % ,74 %或100 %的密度放养牙鲆 (Paralichthysolivaceus)幼鱼 (体质量1.86g±0.18g,全长6.3cm±0.27cm)。同时另在放养密度100%组中混养石莼40.00g。经45d饲养 ,混养石莼组中的牙鲆生长最快 ,水质好 ,饲养系数最低。在单养组中 ,牙鲆生长速度由快至慢依次为48 %组>74%组>100%组。牙鲆体长增长和体质量增长速度最快的密度分别为80 %～100%和100%～110 % ,低于或高于此密度鱼的增长均减慢。

A 45-day experiment was conducted to test the effects of 48%, 74%, and 100% stocking densities (percentage of ventral fish area to bottom tank area) and polyculture with Ulva pertusavar on growth in Japanese flounder (Paralichthys olivaceus) juveniles in twelve 27 cm diameter plastic baskets with volume of 40 liters. The fish were stocked into net cages placed in the baskets and fed formulated pellet feed to satiation. There were better growth and higher food utilization in the polyculture than in monoculture. It was found that the fish in 48% groups had the best growth, better followed by the 74%groups, then worse in the 100% groups in monoculture of fish. The maximum stocking density for good growth in body length and body weitht was 80%～100%, and 100%～110%, respectively.