IMPACTS OF INTRODUCED AQUACULTURE SPECIES ON MARKETS FOR NATIVE MARINE AQUACULTURE PRODUCTS: THE CASE OF EDIBLE OYSTERS IN AUSTRALIA

Economic competition between introduced and native aquaculture species is of interest for industry stakeholders since increased production can affect price formation if both aquaculture species are part of the same market or even substitutes. In this study, we focus on the Australian edible oyster industry, which is dominated by two major species—the native Sydney rock oyster (grown mainly in Queensland and New South Wales) and the non-native Pacific oyster (grown mainly in South Australia and Tasmania). We examine the integration of the Australian oyster market to determine if there exists a single or several markets. Short- and long-run own, cross-price and income flexibilities of demand are estimated for both species using an inverse demand system of equations. The results suggest that the markets for the two species are integrated. We found evidence that the development of the Pacific oyster industry has had an adverse impact on Sydney rock oyster prices. However, our results show that both species are not perfect substitutes. Demand for Sydney rock oysters is relatively inelastic in the long run, yet no long-run relationships can be identified for Pacific oysters, reflecting the developing nature of this sector.     

BIOECONOMIC MODELING OF SHRIMP AQUACULTURE STRATEGIES FOR THE MAHAKAM DELTA,INDONESIA

Bioeconomic modeling was used to evaluate traditional and extensive shrimp production in the Mahakam Delta and impacts of adopting Better Management Practices (BMP) for semi-intensive and integrated mangrove-shrimp culture. Modeling outcomes indicate that traditional production is not financially viable, failing to generate a positive 10-year Internal Rate of Return (IRR). Such practices persist in the Mahakam Delta as capital costs have been depreciated against past financial returns, input costs are negligible, risks are minimal, opportunity costs are low and options to intensify production have been retained by producers. Returns from BMP-guided semi-intensive culture (20% IRR) are marginally higher compared to extensive culture but entail a 10-fold increase in operating costs and greater risks. Integrated mangrove-shrimp production gives a reasonable IRR (53%) but costs remain high, management demanding and risks uncertain. Risk adverse operators with short-term leases may favor traditional and extensive practices. Sustainable intensification, allied to social capital development and rehabilitation of mangrove ecosystem services and environmental flows, is needed to reconcile multiple demands.     

冷冻对轮虫休眠卵上浮率的影响↑（*）

本文报道了冷冻对轮虫休眠卵在水中上浮率的影响，一次冷冻（２４小时）可使各种轮虫休眠卵在水中的上浮率平均提高近５０％，使晶囊轮虫休眠卵的上浮率提高９０％左右。多次反复冷冻能使各种轮虫休眠卵的上浮率提高８５％左右，冷冻时间在８～１０４小时间，延长冷冻时间不会影响轮虫休眠卵的上浮率，并分析了冷冻处理后的休眠卵在水中和糖盐高渗液中上浮率提高的机理，讨论了冷冻处理在轮虫休眠浮选，定量以及土池轮虫生产中的意义     

DEMAND FOR AQUACULTURE PRODUCTS IN TAIWAN: AN APPLICATION OF THE GENERALIZED MODEL

ABSTRACT

Policy decisions on what aquaculture products to develop require information on consumer demand for cultured species. However, information on the structure of demand for aquaculture products is limited and what few studies there are in Taiwan, where aquaculture is a major industry, suffer from methodological problems. To clear up some of these problems, we used modified nonnested testing techniques and performance forecasting to determine which generalized models could best estimate the demand for Taiwanese aquaculture products. The results of modified nonnested testing of the aquaculture demand system showed that prices predetermined and quantities predetermined could be used to estimate demand. The generalized ordinary demand model was able to better forecast performance than the generalized inverse demand model. We used the likelihood ratio test to discriminate among the four competing models for the generalized ordinary model; the AIDS model could be more suitably applied to the data. A more general model that is able to incorporate different dynamic structures (partial adjustment, first autoregressive, and static). This general framework is applied to the AIDS model. The first autoregressive AIDS model we used to calculate the own and cross-price elasticities for milkfish, tilapia, shrimp, shellfish, and carps found that price elasticities varied across fish type, that some products had high long-run own price elasticities, and that the demand for aquaculture products was largely determined by inertia.     

绳拖网网口结构设计和装配工艺

本文主要阐述适用于我国东海和黄海渔场的双船两片式底层绳拖网网口结构设计，上、下纲和悬纲长度计算方法及其装配工艺。根据绳拖网的上纲和下纲的工况特点，上纲呈抛物线状；下纲呈悬链线状，分别依据其各自的曲线方程组求算。关于悬纲和上、下纲之间的装配工艺，是按我国底层拖网特点设计的。经生产实践，证实这些设计和装配都是合适的。     

SIMULATED ANNEALING FOR COST-EFFECTIVE TRANSPORT OF LIVE AQUACULTURE PRODUCTS

This study elucidates a vehicle routing problem with a single depot and multi-customers, in which a simulated annealing approach is used for transporting live aquaculture products. In contrast with previous models that focused on cost, transportation distance, or time, this study separately optimizes a sole depot with multi-customer flows by using a mathematical model that considers transportation, survival rates, and cost classifications of live aquaculture products. Specifically, the simulated annealing approach is adopted to facilitate the multi-customer transport vehicle routing problem on carrier selections and their interactions. The proposed model is applied to several relevant scenarios with cost-effectiveness. The computational results demonstrate the effectiveness of the model for solving the problem of transporting live aquaculture products.     

ANTICIPATING THE GROWTH OF AN OCEAN AQUACULTURE INDUSTRY

In assessing the future expansion of aquaculture in coastal-ocean environments, most studies focus only on the constraint posed by the local environmental assimilative capacity. In open-ocean environments, however, the assimilative capacity is difficult to gauge. We develop an alternative economic approach for projecting the growth of the open-ocean aquaculture industry. We evaluate equilibria in the market for seafood, where the product may be supplied either by a wild-harvest fishery or open-ocean aquaculture or both. In our framework, the net demand for farmed fish determines the size of the aquaculture industry and, in turn, the levels of pollution discharges. We illustrate our approach with a case study of a groundfish fishery and the proposed open-ocean aquaculture of Atlantic cod in New England. We find that, for a range of competitive production costs for aquaculture, the optimal industry structure would comprise both a wild-harvest fishery and aquaculture.     

THE ECONOMICS OF AQUACULTURE INSURANCE: AN OVERVIEW OF THE U.S. PILOT INSURANCE PROGRAM FOR CULTIVATED CLAMS

One important issue affecting the continued growth and success of the aquaculture industry is risk management. Aquaculture producers face a number of production risks (e.g., weather, disease) that substantially affect their output quantity and quality. Crop insurance is one important potential mechanism for managing these risks, but aquaculture has historically had limited insurance availability in the United States, in part because of unique challenges associated with implementing crop insurance programs in aquatic settings. The Cultivated Clam Pilot Insurance Program, which began in 2000 in four Atlantic Coast states, is the first United States, federal crop insurance program for aquaculture. This program experienced relatively high loss ratios in the early years of the program, but substantial modifications beginning with the 2004 crop year resulted in a significant improvement in actuarial performance. Experiences with clam insurance can provide insight into the potential development and application of insurance programs for other aquaculture products.     

鱼类胚胎低温冷冻保存降温速率研究

在低温下采用慢速降温速率，以０．２－０．５℃／分降至－４０℃以上温度，胚胎获得２０％以上成活率。在超低温下采用快速降温速率，以２℃／分降至－４０℃，再以１０℃／分降至－１９６℃，胚胎获得了９０％以上复活率。     

水温对石蛙人工孵化影响的试验研究

利用地下水微流水状态下孵化石蛙卵子，初步试验结果表明：水温对石蛙卵子的出苗率影响很大，21-23℃是其最适宜的卵化水温，当水温高于25℃，石蛙孵化开始出现畸形苗，32℃是其孵化的致死水温。     

海洋增殖渔业的理论和若干技术问题的探讨

海洋增殖渔业(Marine Propagated Fisheries)，在日本称为栽培渔业(Cultivating Fisheries)，在其他国家又称为海洋牧业(Marine Ranching)。我们考虑到“栽培渔业”和“海洋牧业”这两个概念在我国都不能反映这种渔业的特点，因此使用海洋增殖渔业这一名称。     

公海渔业的限制与发展——国际渔业法律环境剖析

本文阐述了公海渔业的概念,论述公海捕鱼自由是国际海洋法中的一条基本规则,指出公海捕鱼的权利必须在国际法规定的有关规则限制下行使。根据近年来一些沿海国家试图对公海渔业进行管辖的实际状况和1992年国际上一些主要的国际渔业会议的主要精神,本文分析了国际渔业法律环境的发展趋向,预测了今后国际上进一步限制公海渔业的可能形式,并结合我国公海渔业发展的实际情况,提出我国发展公海渔业过程中应当给予重视的几个问题。     

急升温对十种甲壳动物存活率的影响

温度是影响海洋生物生长繁殖和分布的一个重要因子。在适温范围内,生物可以正常生长繁殖;超过适温范围时,生物的行为活动以及生长繁殖都将受抑制,甚至导致死亡。张伟权等(1980)、王克行等(1984)曾观察过温度对中国对虾幼体存活率和生长的影响,黄加祺和郑重(1986)、林森杰和李松(1988)、Bhattacharga(1984)、Bradley(1975)、Moreira(1982)分别报道过温度与某些桡足类生长、繁殖及存活率关系的实验结果。有关虾、蟹等经济动物和浮游甲壳类的行为生态与分布,不少学者已作过较细致的研究和论述。     

THE FARMING PRACTICES AND ECONOMICS OF AQUACULTURE IN THAILAND

ABSTRACT

The paper reviews freshwater and coastal aquaculture practices in Thailand, and compares the productivity, costs, and benefits across various types of cultivation and various intensities of production. The paper is based on data that were collected in surveys conducted during 1998–2001 by the Department of Fisheries (DOF), Thailand and the WorldFish Center. More than 22% of Thailand's fish supply comes from aquaculture, with coastal aquaculture accounting for more than 88% of this in terms of value. Intensive culture of shrimp is the dominant form of coastal aquaculture, occupying 69% of the area under production. However, in some regions, the average net profit/kg of intensive shrimp culture is negative, and semi-intensive farming, with relatively lower fixed investment and operating costs, delivers the highest rate of return on investment. On the coast, grouper and sea bass are the most important cage-cultivated species, achieving an economic rate of return as high as 92%. In the same environment, culture of mollusks, such as green mussels, oysters, and blood cockles, is widespread. It can also be economically sustainable, with relatively low capital and operating costs. Although the relative share of freshwater aquaculture production is declining, the level of output has been increasing rapidly. While the average production from monoculture of carnivorous species is higher than that from polyculture, the average capital investment and operating costs associated with the former are also higher. The expansion of freshwater polyculture and of mollusk culture in coastal areas would greatly assist poor fish farmers.     

渔业资源评估专家系统设计及实践

利用国内外常用的渔业资源评估模型及东海主要经济种类渔业资源评估专家知识,应用面向对象的知识处理系统（ＯＫＰＳ）作为开发工具,开发了渔业资源评估专家系统。运用该专家系统可以对东海主要经济种类,如带鱼、鲐鱼和马丽等的资源量、可捕量进行评估和预报。     

海蜇帆张网的设计与生产试验

本文报道了1996～1997年江苏省启东市海蜇张网的改革和试验结果。文章分析了海蜇鱼发多变、体型较大和常漂游于水域中上层的特点,提出用锚张网替代桩张网,使用大网目以扩大网口并在网口两侧加装柔性帆板以增大水平扩张。改进设计的海蜇帆张网经较大规模的海上生产试验在1997年取得大面积丰收。单船平均网次产量比原用桩张网增加3倍多。文章针对吕四渔场流速(2.5～3.5节)对网具规格及阻力、锚具重量和爬驻力以及渔船起网鼓轮绞拉力之间的相互制约关系提供了经验计算式。文章指出,这种海蜇帆张网的推广、使用必须强化管理,以确保伏休制度得到贯彻。     

A COMPARISON OF THE ECONOMIC PERFORMANCE OF OFFSHORE AND INSHORE AQUACULTURE PRODUCTION SYSTEMS IN KOREA

The economic performance of the current inshore rock bream aquaculture industry conducted in Yeosu, Korea was compared with a pilot commercial scale offshore aquaculture farm in Jeju, Korea. Data was collected from 12 inshore farms and two production cycles of the offshore farm for use in Monte Carlo simulations run over a ten year time horizon. Net present value was compared for the inshore farms and two survival rate scenarios for the offshore farm. The offshore farm is expected to have a higher survival rate if it can withstand tsunamis and avoid pollution, disease and red tide impacts that are prevalent inshore. When the offshore farm was modeled with its observed higher survival rate, its average net present value ($1,016,483) significantly outperformed the inshore farms average net present value ($182,153). In the second scenario, the offshore farm survival rate was lowered based on performance data from the inshore farms. Not surprisingly, given the higher investment costs, the offshore farm performed poorly in terms of average net present value ($-137,142) compared to the inshore farms when it no longer had the advantage of high survival rates.