ECONOMIC RISK ASSESSMENT OF A SEMI-INTENSIVE SHRIMP FARM IN SINALOA,MEXICO

In Mexico shrimp farming is the most important aquaculture activity. However, its sustainable development has been threatened in recent years by the economic risk associated with low yields caused by outbreaks of viral diseases. A stochastic bioeconomic model was developed to analyze the economics of farm management adjustments as a response to disease risks, using pond-level data from a farm operating in the State of Sinaloa, Mexico, during the period 2001–2005. The data base analyzed included different combinations of stocking density (in the range 6–30 PL/m²) and culture time (from 12 to 31 weeks), which allows for wider application of the simulation results, even at the industry level. Results from this study indicate that operating costs would increase by 33% if the farmer would choose to market product directly. Scenarios with lower stocking densities and intermediate culture times generated the highest probabilities 6–9 PL/m² 16–19 weeks (76%/100%/70%), and 10–14 PL/m² 20–24 weeks (72%/99%) of achieving superior economic performance, as demonstrated by achieving the target reference point of 35% operating profit margin ratio. The study reinforces the value of the current trends in Sinaloa to reduce stocking density as a good management practice to decrease the impact of diseases. This study also provides important additional knowledge on the specific economic results and risks associated with the combination of these two management variables at different levels.     

RISK ASSESSMENT OF A SHRIMP AQUACULTURE INVESTMENT IN FLORIDA

A stochastic simulation model was developed to examine the impact of risky economic variables on the profitability of a small-scale shrimp farm. Sources of risk included input and output prices, random-kill events, and hurricane damages. Success was measured using the probability distribution of the net present value (NPV). A baseline model that assumed capital costs of $493,993, a stocking density of 100 shrimp per m², a harvest survival of 80%, and a discount rate of 8% failed to generate a positive NPV. Subsequently adding a $0.66 price premium also failed to establish a positive NPV. Further reducing initial capital costs by 50% resulted in a 2% probability of a positive NPV. Incrementally reducing the discount rate generated increasingly positive NPV probabilities ranging from a 9% probability of success (7% discount rate) to a 94% probability of success (3% discount rate). Additional analyses suggested that probabilities of financial success were also sensitive to random-kill and hurricane events.     

EFFICIENCY ANALYSIS AND THE EFFECT OF POLLUTION ON SHRIMP FARMS IN THE MEKONG RIVER DELTA

This article investigates the efficiency of intensive, semi-intensive, and extensive shrimp farming practices as well as the difference between the upstream and downstream efficiency of shrimp farms in the Mekong River Delta (MRD), Vietnam. Our article is the first to compare the efficiency of the 3 shrimp practices and investigate the difference between the efficiency of downstream and upstream farms. The efficiency of shrimp farms is measured using group-frontier and meta-frontier analysis on a sample of 292 farms. The results show that, on average, shrimp farms are inefficient; extensive farms are more efficient than intensive and semi-intensive farms; and, controlling for key socio-economic factors, upstream farms are more efficient than downstream farms, suggesting that pollution from upstream farms may influence shrimp farm efficiency. The results give some direction for improvement and some evidence to shrimp farmers and policymakers in the MRD to take the pollution problem seriously and find solutions for more sustainable development.     

大连紫海胆人工育苗的初步研究

本文报道了有关海胆人工育苗的方法,并对大连紫海胆幼虫的生长发育和变态作了详细描述。大连紫海胆的幼虫可分为,棱柱幼虫、二腕长腕幼虫、四腕长腕幼虫、六腕长腕幼虫和八腕长腕幼虫五个时期。在山东省荣城浬岛海区,大连紫海胆的育苗时间为7—8月。在水温为23—24℃时,自受精卵发育至变态成幼海胆的时间大约需要19—20天。幼虫的饵料以角毛藻为最佳,而幼海胆的饵料早期为底栖硅藻,后期以石药较为合适。     

中国对虾养成期间虾池水体和底质中细菌含量的变化

中国对虾养成期间虾池水体和底质中细菌含量的变化高尚德，陈旭仁，吴以平（青岛海洋大学，２６６００３）（青岛教育学院，２６６００１）关键词养虾池，细菌数量，变化ＶＡＲＩＡＴＩＯＮＯＦＴＯＴＡＬＢＡＣＴＥＲＩＡＮＵＭＢＥＲＩＮＳＨＲＩＭＰＰＯＮＤＷＡＴＥＲ...     

TESTING FOR MARKET INTEGRATION AND THE LAW OF ONE PRICE IN WORLD SHRIMP MARKETS

Using import price data from Japan, United States, and the European Union, shrimp price movements in these markets were evaluated to test if it denotes an integrated world market for shrimp. Cointegration techniques were utilized to investigate if prices in these markets share a common stochastic trend and if the law of one price holds. Results indicated a strong link amongst Japanese, American, and European markets. The results on the aggregated shrimp markets were checked against the results at a more disaggregated level. Data from wholesale markets in Tokyo, New York, and Europe for specific shrimp products confirm the integrated nature of shrimp markets. Evidence also supports the law of one price in shrimp markets.     

光合细菌在虾病防治中的作用研究

本文着重研究光合细菌(PSB)在虾病防治中的作用,结果表明:对虾养殖池施用光合细菌后,随PSB浓度的增加水质、底泥中弧菌和异养细菌数量而逐渐减少,表明了PSB具有调节和改善养殖的微生态环境的作用。PSB还能降低底泥中的有机质和硫化物含量,降低COD含量,并提高养殖水体的溶解氧,改善水生环境。本文还分析了PSB在长毛对虾幼体培育中的应用效果,光合细菌的营养通过食物链的传递,促进对虾生长,增强对虾抗病能力,降低发病率和死亡率。     

中国对虾（Penaeus chinensis）养成期虾池水体和底质及虾体异养菌和弧菌含量的变化

本文报道了辽宁省瓦房店市邓屯乡高家养虾场对虾养成期虾池水体和底质及虾体异养菌和弧菌含量的变化。结果表明外海水中异养菌数量为１０￣４～１０￣５个／毫升，弧菌数量为１０￣２～１０￣３个／毫升，虾池水中异养菌数量为１０￣４～１０￣５个／毫升，弧菌数量为１０￣２～１０￣４个／毫升，底质中异养菌数量为１０￣５～１０￣７个／克，弧菌数量为１０￣３～１０￣４个／克。虾体肌肉中异养菌数量为１０￣３～１０￣５个／克，弧菌数量为１０￣３～１０￣５个／克；肝胰脏中异养菌数量为１０￣３～１０￣７个／克，弧菌数量为１０￣２～１０￣７个／克；肠道中异养菌数量为１０￣６～１０￣７个／克，弧菌数量为１０￣６～１０￣７个／克。     

单克隆抗体酶联免疫技术检测对虾皮下及造血组织坏死病的病原及其传播途径

用单克隆抗体ＥＬＩＳＡ技术对１９９４年５月～７月自山东和辽宁采集的虾池和海区材料，包括对虾、浮游生物、小型甲壳类生物、鱼类、底泥及饲料等共１９２个样品进行了对虾暴发性流行病病原ＨＨＮＢＶ的检测。结果表明，对虾中的ＨＨＮＢＶ阳性与虾池发病情况基本相符，用单抗ＥＬＩＳＡ方法可提前２０～４０ｄ对虾池的发病可能性作出预报；桡足类浮游生物的带毒率高于对虾，且其阳性的出现早于对虾，沿岸海区的桡足类浮游生物有较高的阳性率，它可能是对虾暴发性流行病的主要病原携带者；部分地区的卤虫也带有ＨＨＮＢＶ，同时还从糠虾等小型甲壳类生物中检出了病原。     

中国内陆盐湖卤虫资源开发利用的研究

我国内陆盐湖卤虫资源分布地区约有４３处，其中重点产区有内蒙古的额吉淖尔、黄旗海；青海的尕海、小柴旦湖；新疆的艾比湖、巴里坤湖；山西的解池等７处。卤虫资源量为２５０００～３００００ｔ／ａ；卤虫卵５００～７００ｔ／ａ；可开发量：鲜卤虫１５００ｔ／ａ，原料卤虫卵２００～３００ｔ／ａ。研究了主要盐湖卤虫生物学特性和投喂对虾幼体的饵料效果以及卤虫的孵化特性和加工工艺。并对我国内陆盐湖卤虫资源进行了评估，提出了繁殖保护和开发利用的意见。     

温度与盐度和缢蛏幼体生存、生长及发育的关系

本文以长期生活在较高盐度(26—28‰)海域的亲蛏所繁衍的幼体为材料,探索温度和盐度单因子及双因子结合与幼体生存生长、发育的相互关系。浮游幼虫期适盐范围为8.4—32.4‰,最适盐度为12.4‰,稚贝适盐范围为8.4—28.4‰,最佳盐度为12.4‰。温度对幼体的影响,是受盐度高低所支配。在盐度为28.4‰生境中培育,浮游幼虫期适温范围为17—25℃,最适温度为21℃,稚贝适温范围为13—25℃,最适温度为17℃,幼体对25℃以上的较高温度的忍耐力较差。若在最适盐度(12.4‰)中培育,浮游幼虫期最适水温为25℃,稚贝最适水温为21℃。幼虫对较高盐度的忍耐力比对较低盐度的忍耐力来得强。     

史氏鲟南移驯养及生物学的研究:Ⅲ.仔鱼的开口摄食

用单一的水蚯蚓、卤虫无节幼体、池塘浮游动物、人工配合饲料投喂及先卤虫无节幼体后人工配合饲料混合投喂等五种方式培育史氏鲟仔鱼。结果为：卤虫无节幼体是史氏鲟最好的开口饵料,可获得高的成活率和生长率;开口摄食后３－５天,即可开始投喂人工饵料进行食性驯化,２０日龄的鱼苗可获得满意的饵料驯化效果。     

濒危物种─—新疆大头鱼的生态和资源调查与保护对策的研究

１９９２年起对濒危物种──新疆大头鱼的生态进行了调查。调查的水域有：叶尔羌河、阿克苏河及其上游托什干河和库马里克河、塔里木河、博斯腾湖及上游开都河和天鹅湖、大西海子水库、渭干河水系及克孜尔水库和车尔臣河及新发现的喀依拉克湖等水域，行程１００００多ｋｍ。初步查清了新疆大头鱼的分布范围、生态要求及其数量演变。新疆大头鱼分布的海拔高程为８００～１２００ｍ之间，最高不超越１５００ｍ。栖息于水温较高的静水或缓流的湖泊中，仅为了产卵进行短距离的溯河徊游。现存有新疆大头鱼的水域仅为阿克苏河下游的艾西曼湖群、车尔臣河的喀依拉克湖和渭干河水系的克孜尔水库，并在库区下的河道中发现幼体。目前新疆大头鱼物种已极度濒危。新疆大头鱼系裂腹鱼亚科中生长快、个体大、性成熟年龄晚、繁殖力低的大型食肉性鱼类。运用Ｖｏｎ．Ｂｅｒｔａｌａｎｆｆｙ的理论生长方程求得的生长参数：－Ｋ＝０．０６３；ｔｏ＝０．２７５；Ｌ＝１１８．２ｃｍ；Ｗ＝２５８８４ｇ；ｔｉｐ＝１７．１龄；ｔｍａｘ＝４７．２龄。与历史上捕获的最大个体基本一致。并对新疆大头鱼的食性、繁殖、及其生态环境进行了初步研究。新疆大头鱼濒危的原因：１、新疆大头鱼生物学特性的本身决定它对环境要求苛刻