Integrated culture of the spiny lobster (Panulirus ornatus), the green mussel (Perna viridis) and seaweed (Kappaphycus alvarezii) in Van Ninh District, Khanh Hoa Province, Vietnam | |
| Author | Vo Chi Dung |
| Call Number | AIT Thesis no.AQ-08-31 |
| Subject(s) | Spiny lobster culture--Vietnam--Khanh Hoa Mussels--Vietnam--Khanh Hoa Marine algae--Vietnam--Khanh Hoa |
| Note | A thesis proposal submitted in partial fulfillment of the requirements for the degree of Master of Science in Aquaculture and Aquatic Resources Management |
| Publisher | Asian Institute of Technology |
| Abstract | This study was conducted to assess technical and economical feasibility of the integrated lobster-mussel-seaweed cage culture system in Xuan Tu village, Nhatrang, Vietnam. The study consisted two parts. A short questionnaire survey was used to gather technical and economic information from thirty lobster cage culture farmers. An experiment comprised two treatments were conducted to assess the growth rate, biomass of green mussel and nutrient retention (total nitrogen and phosphorus) of mussels (Perna viridis) and seaweed (Kappaphycus alvarezii) were assessed for 123 days during this study. The treatments were green mussel and seaweed culture in the vicinity of the lobster cages (Treatment 1) and 1 km away from the lobster cages (Treatment 2) Green mussel was cultured using hanging method with a density of 1 kg per rope. One meter long ropes were hung at 20-120, 50-150 and 100 - 200 cm depth in the treatment 1. Average weight of seed was 7.05±2.7 g individual-1. Seaweed was placed inside a small net cage to protect from rabbit fish and hung around lobster cages. Seaweed was also hung vertically inside the lobster cages without a net cage. Density of seaweed was 0.5 kg rope-1. Water quality factors (T, salinity, pH, transparency level, suspended solid, total N and P) were measured fortnightly. Total N and P loss were estimated using the food conversion ratio (FCR). There are two types of lobster cage in Xuan Tu (wooden fixed cage and floating cage). The lobster feed comprised with trash fish, bivalves, small crap and small shrimp are used by the all interviewed farmers. Lobster cage culture encountered common diseases such as black grill, red body and moulting inability. The growth rate and biomass of green mussel and seaweed at the vicinity of lobster cages were higher than control site (P<0.05). However, there were no significant differences in growth rate and biomass of green mussel and seaweed between 20-120, 50-150 and 100-200 cm depths at control site and lobster site (P>0.05). Growth rate of green mussel near the lobster cages were 19, 21 and 24g individual-1 at 20-120, 50-150 and 100-200 cm water depth and in the control treatment it was 6.8, 7.3 and 9.3 g individual-1, respectively. The highest growth rate and biomass of seaweed were observed in the treatment 1 when seaweed was placed inside of the lobster cage without small net cage. (711% weight gain with 3.6 kg rope-1). Seaweed placed in net cages near the lobster cages had 220% weight gain with 1.6 kg rope-I and seaweed at the control site had 149% weight gain with 0.74 kg rope-1, respectively. The highest (10% day-1) relative growth rate (RGR) was observed in seaweed placed inside lobster cage. Seaweed placed inside the net cages and placed near net cages had a RGR of 1.2% day-1 and net cages placed 1 km away had the lowest (0.7%) RGR. Total N and P loss from lobster cage were about 1.12 and 0.26 kg cage-1, respectively. Total maximum N and P were removed by green mussel and seaweed approximately 0.53 and 0.01 kg cage-1 respectively. Green mussel and seaweed reduce some of the negative effects on the environment by removing the released N and P from lobster cage culture. It was found that the total cost of lobster monoculture cage system was approximately US$1,804 cage-1 crop-1. Net profit was US$717 cage-1 crop-1. Feed (35%) and seed (33%) costs were the main factors contributing to the total operation cost. Feed and seed costs in the integrated lobster-mussel-seaweed cage culture system accounted for 32 and 35%, respectively. The net profit per cage unit was US$ 819, which was 14% ($102) higher than the lobster monoculture. It was found that there is a good potential to develop integrated lobster culture with green mussel and seaweed in Xuan Tu village as it has around 7000 lobster cages. The estimated total green mussel and seaweed production capacity are 2,450 and 8,500 tons cage-1 crop-1, respectively. The corresponding N and P removal are 625 and 26.5 tons, respectively. |
| Year | 2008 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Aquaculture and Aquatic Resources Management (AQ) |
| Chairperson(s) | Yakupitiyage, Amararatne; |
| Examination Committee(s) | Gallardo, Wenresti G.;Ranamukhaarachchi, Senaratne Leelananda;Lin, C. Kwei ; |
| Scholarship Donor(s) | Netherlands; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2008 |