浮筏养殖虾夷扇贝的自然稀疏效应

为了研究虾夷扇贝浮筏养殖自然稀疏效应和科学养殖密度,2009年8月—2010年7月,对不同密度梯度的3个贝龄虾夷扇贝进行浮筏养殖现场实验。在自然稀疏条件下,逐月调查浮筏养殖不同贝龄的虾夷扇贝壳长生长、湿重增长和累计死亡率,并估算了适宜的扇贝浮筏养殖密度。结果表明,在不同养殖密度条件下,3 个贝龄扇贝周年壳长生长都没有显著差异;1龄贝壳长增长最快,年均增长29.53 mm;2龄贝壳长年均增长23.50 mm;3龄贝壳长增长较慢,年均增长15.47 mm;3个贝 龄扇贝周年湿重增长都没有显著差异,3龄贝和2龄贝湿重增长较快,3龄贝的年均增长约54.07 g,2龄贝的年均增长约37.80 g,1龄贝的年均增长约14.69 g;2 龄贝、3龄贝各养殖密度梯度之间累计死亡率都没有显著差异,3龄贝死亡率介于76.30%～83.33%,2龄贝死亡率介于88.89%～91.78%,养殖密度为150个/层的1龄贝与80个/层和50个/层的1龄贝累计死亡率差异显著。依据自然稀疏模型,浮筏养殖适宜密度3龄贝为4～5个/层;2龄贝为8～16个/层,1龄贝为29～124个/层。

Effects of self-thinning in the sea of raft culture of Pationopecten yessoensis

A field experiment of different density of three shellfish ages was carried out in the sea of raft culture of Pationopecten yessoensis in Changhai County from August 2009 to July 2010 to study the self-thinning effect and to estimate the optimal culture density using the monthly data of the growth of shell length,wet weight growth and cumulative mortality.No statistical difference was found in the anniversary shell length growth(P>0.05)in different density for the surveyed scallop samples of every shellfish age.The shell length of the first-year scallop grew fastest with an average annual growth 29.53 mm,followed by 23.50 mm for the second-year shell growth and 15.47 mm for the third-year shell.The anniversary of wet weight growth was not significantly different(P>0.05)either,the wet weight growth of the first-year scallop,the second-year and the third-year scallop were 14.69,37.80 and 54.07 g,respectively.The difference in cumulative mortality of different density groups for second-year and third-year shellfish was not statistically significant(P>0.05) with the third-year shellfish mortality ranging from 76.30% to 83.33% and the second-year shellfish mortality rate ranging from 88.89% to 91.78%.The cumulative mortality of the first-year scallop with cultural density of 150 ind/layer was significantly different(P <0.05)from that of the density of 80 ind/layer and 50 ind/layer.Based on self-thinning model,the suitable raft breeding density is 4-5 ind/layer in third-year scallop,8-16 ind/layer in second-year,29-124 ind/layer in first-year,respectively.