分段养殖模式在凡纳滨对虾(Litopenaeus vannamei)养殖过程中的应用

Application of Culturing in Stages in the Shrimp Culturing Pond

通过测定凡纳滨对虾(Litopenaeus vannamei)生长性能和监测池塘水质变化,研究分段养殖模式在对虾养殖过程中的应用价值。养殖实验在6口池塘内(0.267 hm^2/口)进行,首先在其中2口池塘内进行对虾的中间培育,养殖密度为300×104尾/hm^2。经过36 d和48 d的中间培育后,将对虾先后转移到其他4口池塘内,养殖密度为60×10~4尾/hm^2,分别记为T_1和T_2组。剩余的对虾继续养殖在中间培育池塘内,记为C组。结果显示,经过分段养殖的T_1和T_2组对虾,在分池养殖阶段7 d内,生长速度均明显增加,其特定生长率(SGR)分别达到9.36%/d和6.76%/d;养殖期间,T_1组具有最大的SGR(9.36%/d)和饲料投喂量,然而其饲料系数(FCR)(1.053)高于T_2组(0.822);经过分段养殖的对虾FCR均低于C组(1.082)。在分池养殖阶段的大部分时间,T_2组对虾的SGR高于T_1组;C组NH4+-N、NO_2--N和Chl-a浓度低于T_1组和T_2组,而颗粒物含量(T_PM)和总磷(T_P)高于T_1组和T_2组;T_2组Chl-a含量明显高于T_1组和C组。结果显示,经过48 d中间培育后,即对虾体重约为2 g时进行分池养殖仍可保证对虾在较长时间内保持较大的生长速度,对于饲料的节约具有重要意义。由于分池养殖阶段具有较多的饲料投喂,经过36 d中间培育后的对虾具有最大产量。分池养殖池塘内饲料投喂少于全期养殖,有利于养殖系统的稳定,然而单位时间内投喂量增加则会影响水质。分段养殖模式在提高分池养殖阶段对虾的生长速度和保持水质稳定方面具有重要的应用价值。

The effects of culturing in stages on the growth of shrimp Litopenaeus vannamei and the water quality were investigated from April to July in 2015. Experiments were conducted in 6 shrimp culturing ponds （2650 m2, 53 m × 50 m each）. The shrimp was first cultured in 2 ponds with a density of about 300x 104 ind/hm2 for early cultivation. The subjects were stocked at 3 culturing time points, 36, 48 and 83 days, and were referred to as T1, T2, and C groups respectively. After early cultivation, the shrimp in the T1 and T2 groups were divided into two ponds with a suitable density （60×104 ind/hm2）. The survival rate, the growth of shrimp, and the water quality were evaluated during the experimental period. The growth increment of weight and length during the first week was significantly boosted and the specific growth rate （SGR） for TI and T2 reached 9.36 %/d and 6.36 %/d respectively. The Zl group showed the highest SGR and food consumption during the experiment, and the feed conversion ratio （FCR） was higher in T1 （1.053） than in T2 （0.822）. In most of the divided culturing periods, the T2 group maintained a higher SGR. Compared to the T1 and T2 groups, the C group had lower concentrations of NH4＋-N and NO2- -N, a higher level of total particle matter （TPM）, and a lower content of Chl-a. The T2 group had the highest Chl-a content. These results indicated that the shrimp might achieve rapid growth later if divided into different ponds after a proper cultivation period （48 days）. The organic matter accumulation in the pond decreased in the early cultivation, which helped improve the water quality of the pond. However, the water quality may worsen when the feed consumption in the pond reached a certain level in unit time. In conclusion, divided culturing in the different ponds could improve both the growth of shrimp and the water quality.