ASSESSING HAWAII'S AQUACULTURE FARM AND INDUSTRY PERFORMANCE

This investigation uses farm-level data from the U.S. Census of Agriculture to evaluate the economic performance of the aquaculture industry in Hawaii. We first examine the entire aquaculture industry by assessing its profitability, efficiency, and input cost structure over time and across economic farm sizes; we then proceed to analyze the farms at the individual subsector levels of crustacean, Chinese catfish, other foodfish, and ornamental farms. The results reveal a wide variation in performance across farms, even within the same subsectors. In 2007, 57.6% of the aquafarms generated a profit; however 39.4% of the farms were found unable to cover their variable cash expenses. The presence of significant economies of scales were detected in performance with full-time operations being found more profitable and efficient than part-time operations. Finally, Hawaii's labor cost share for aquaculture enterprises is about 3.5 times greater than that found on the continental United States.     

Mine Water Aquaculture as an Economic Development Strategy

Abstract

This study involves a comprehensive economic analysis of mine water aquaculture. First, the costs and benefits are quantified using standard enterprise budgeting and feasibility techniques. Next, a price analysis is conducted to determine the underlying probability distribution and generate confidence intervals for use in planning purposes. Then, the relationships between mine sites and unemployment, and mine sites and tourism, respectively, are illustrated using a spatial analysis. Finally, the potential economic development impacts of growth in the aquaculture industry on statewide output, income, and employment are estimated. The results have implications for entrepreneurs and the aquaculture and coal industries in Appalachia and other parts of the US where coal mining can be linked to fish farming, water conservation, and recreation.     

斑点鳟陆海接力养殖初步研究

为有效突破中国北方网箱养殖品种少的缺陷,并合理利用闲置网箱,通过陆海接力养殖模式,开展斑点鳟(♀Oncorhynchus mykiss×♂Oncorhynchus mykiss)的陆海接力养殖试验,并与工厂化养殖进行了对比,达到提高斑点鳟的养殖存活率,增加经济效益的目的。结果显示:从2013年6月1日至2014年6月19日,3种规格斑点鳟的初始体质量分别为(225.1±36.2)g、(102.8±23.5)g、(55.3±12.3)g,经384 d的工厂化养殖,养成平均质量分别达到(2143.4±253.1)g、(1 763.8±210.3)g、(946.3±120.4)g,存活率分别为91.2%、90.6%、89.3%;经384 d的陆海接力养殖,养成平均质量分别达到(2 408.3±321.2)g、(2 065.5±256.3)g、(1 142.6±156.3)g,存活率分别为87.5%、88.1%、85.3%,其中大规格苗种的平均日增体质量达到8.5 g/d。由此可见,最适宜进行陆海接力养殖的斑点鳟规格为体质量100 g以上的中等规格斑点鳟,且"陆海接力"养殖的斑点鳟具有生长快、经济效益高等特点,是一种值得推广的新型斑点鳟养殖模式。     

Nonparametric estimation of returns to investment in Honduras shrimp research

Abstract

Economic returns to the investment in shrimp research in Honduras by Auburn University researchers, as a part of the Pond Dynamics/Aquaculture Collaborative Research Support Program (1993 to 1998), were estimated using a nonparametric approach. A survey of shrimp growers in Honduras provided data on yield, input application, and prices for their first year of production and for the year 1997. Research investment data included funding from both public and private sectors. Results showed that total factor productivity indices increased from 1995 to 1997 indicating technical progress due to research. When both private and public investment were considered, the internal rate of return to the investment in research was 46%. However, the internal rate of return to public‐sector investment alone was above 6,681%. This indicated that the public funds invested in shrimp research in Honduras have been leveraged effectively with private‐sector capital to generate technological progress.     

我国水产养殖设施模式发展研究

作为世界水产养殖大国,我国的养殖设施模式要走上可持续发展的轨道,应该在为健康养殖提供进一步保障的前提下,更加注重系统在"节水、节地、节能、减排"方面的功效。养殖池塘、流水型养殖设施、循环水养殖设施和网箱养殖设施是我国集约化养殖的主要设施模式。这些设施在发挥巨大生产力的同时,在养殖水环境控制、水资源利用、生产系统效益、系统对环境的影响等方面,不同程度地存在着问题或矛盾,没能发挥出现代设施系统在健康养殖和产业可持续发展上应有的作用。本文在对以上4种主要养殖设施模式进行分析的基础上,结合养殖设施科技领域的研究成果,提出未来我国水产养殖设施模式的发展方向以及需要解决的重大科技问题,包括池塘工程化生态养殖设施、节水型养殖设施、经济型循环水养殖设施、系统化深水网箱养殖设施等4种发展模式。     

Effect of turbidity on the ultraviolet disinfection performance in recirculating aquaculture systems with low water exchange

This research was carried out to study the effect of turbidity on the effectiveness of ultraviolet light (UVC) for removing heterotrophic bacteria (HB) from two commercial recirculating aquaculture systems (RAS). We developed a simple and straightforward UV disinfection model based on water turbidity to predict the cost‐effectiveness of disinfection. The UVC from RAS1 (12.8 m³, 80 L min^?1, indoor system) was tested at 9.2, 9.9, 16.3, 17.2, 23.1 and 28.2 nephelometric turbidity units (NTU) after 24 h of exposure. The RAS2 (140 m³, 1140 L min^?1, outdoor system) was tested at 8.0, 9.2, 11.0, 12.1, 16.0, 24.2, 27.0, 31.3 and 31.7 NTU after 72 h. An increase in turbidity in the water was achieved by rearing Oreochromis niloticus fish. The RAS1 achieved a maximum UV efficiency (89.8%≈1 Log) at 9.2 NTU after 24 h and RAS2 at 8.0 NTU (86.4%≈0.9 Log) after 72 h of exposure. For RAS1, the UVC removed 90% of HB in 24 h when the turbidity was <9.9 NTU. For RAS2, without restrictions on particle size and relatively high phytoplankton abundance, the UV was unlikely to be a cost‐effective way of removing HB at turbidity above 11.0 NTU.     

Effects of water flow velocity and fish culture on net biofouling in fish cages

The effects of water flow, fish feed and cage position on net biofouling was examined in a floating cage fish farm. Fouling of 16 mm mesh net panels suspended inside and outside net cages and exposed to different treatments were monitored weekly until net apertures were completely occluded by the fouling organisms (8 weeks). Results indicate a dramatic reduction in water flow velocity throughout the fish farm due to the cage units themselves and net biofouling. The reduced water flow (<10 cm s^?1) inside net cages promoted rapid net biofouling, while rapid water flow outside the net cages (>25 cm s^?1) kept the net fouling organisms at bay. Although fish rearing in net cages with inputs of commercial pellet feed increased sessile biofouling (222% higher than outside the net cages) and non‐sessile biofouling (570% higher), the type of fish feed used did not significantly affect biofouling development. The study recommends that the geometry of serially arranged net cages, as commonly deployed in tropical tidal estuaries, be reconfigured to improve flow through in order to minimize the impact of fouling.     

俄罗斯鲟(Acipenser gueldenstaedtii)家系构建及不同家系间生长性能比较

为了解决现有网箱养殖中放养苗种需要前期培育、清洗更换网箱工作强度大的问题,研发出一种双层鱼类苗种池塘养殖网箱。双层网箱呈长方形,箱体网衣由上层大网目和下层小网目组成,两种网衣高度均为1 m,鱼苗在下层小网目 (0.42 mm) 水体中培育,随着鱼苗生长逐渐升高水位,苗种在上层大网目 (0.6 cm) 和下层小网目合围的水体中养殖。结果显示,双层网箱可以进行大鳞鲃鱼苗到鱼种的连续养殖,漂浮网箱适合大规格鱼苗 (全长>2.0 cm) 到鱼种的养殖。双层网箱养殖大鳞鲃1龄鱼种的全长、体长、增重率和特定生长率均显著高于漂浮网箱养殖的鱼种。3个月养殖期间,双层网箱不需要更换清洗网箱,漂浮网箱需要更换清洗网箱5次。结果表明,双层网箱大鳞鲃1龄鱼种的养殖效果显著优于漂浮网箱,并且养殖管理工作强度显著降低。为了验证双层网箱苗种选育的养殖效果,以大鳞鲃耐盐碱选育家系为养殖对象,分别在3个660 m²的池塘中平行安装6个相同规格的网箱,进行从鱼苗到1龄鱼种的池塘养殖。在双层网箱养殖条件下,大鳞鲃选育家系1龄鱼种体长为13.87~16.07 cm,体重为34.71~42.07 g,与池塘养殖条件下的1龄鱼种规格相似,并且6个家系呈现出不同的生长性状。研究表明,在池塘中进行多个双层网箱养殖,可为鱼类选育苗种提供相同的养殖条件和准确的生长数据。双层网箱可为鱼类选育苗种提供一种池塘养殖方式。