The Competitive Advantages Arising from Different Environmental Conditions in Seabream,Sparus aurata,Production in the Mediterranean Sea

The economic performance of gilthead seabream, Sparus aurata, aquaculture in Mediterranean countries is not homogeneous despite the availability of a universalized technology and the absence of trade barriers. Differences in competitiveness among aquaculture facilities result, in part, from economic and environmental factors, which are conditioned by the geographical location of the facility. This article aims to identify and analyze the competitive advantages derived from the different environmental conditions in which seabream production has been developed along the Mediterranean Sea. A particle swarm optimization algorithm based on a seabream bioeconomic model was applied to the economic optimization of multibatch aquaculture production. The analysis involved hypothetical fattening farms located in the major areas in which this species is cultured. The water temperature was the only parameter that varied among locations. The average water temperatures in these locations were below the optimum growth temperature, around which growth progressively diminishes. The results of the study showed that the locations with higher average water temperatures and less variable water temperatures allowed the cultivation process to be more economically efficient. The seabream farms located in Greece and Turkey had a competitive advantage in terms of productivity and operating profitability because of more favorable environmental conditions.     

Possibilities of increasing marine biological productivity by artificial upwelling

An increase in biological productivity within defined sea areas may be achieved by creating an artificial rise to the surface (artificial upwelling) of bottom water rich in biological material. Powered by the wave energy in the Black Sea the experimental systems designed by the authors could raise water via pipes from below the thermocline layer from a depth of 200 m. The upwelled water differed appreciably from that in the surface layers. The concentration of nutrients was many times greater than that in the surface water and contributed greatly to an intensive growth of phytoplankton and to an increase in biomass. Prospects for the use of artificial upwelling systems based on sea wave energy are discussed not only with regard to increasing biological productivity of water but also for overcoming a number of other problems.     

Depth matters for bivalve culture in integrated multitrophic aquaculture (IMTA) and other polyculture strategies under non-eutrophic conditions

Bivalve cultivation, in single cultivation or in polyculture (including integrated multitrophic aquaculture; IMTA), is generally limited to eutrophic waters. We carried out a modeling study to test if, under meso- and oligotrophic conditions, depth could be a key factor for bivalve productivity associated to IMTA and other polyculture strategies. We applied the model Farm Aquaculture Resource Management (FARM) at three strata of the water column in two coastal fish farm areas in the Mediterranean Sea, using water column variables sampled seasonally to estimate the potential mussel production. According to FARM, mussel production was high in both areas and, in some cases, almost doubled when mussels were cultured below 25-m depth compared to shallower levels. Phytoplankton abundance is expected to notably influence mussel production compared to particulate organic matter. Thus, in meso- and oligotrophic stratified waters, where chlorophyll maximum is relatively deep, depth can be a key factor for the productivity of mussel cultivation. The obtained results could help to maximize the production of suspension-feeding bivalve cultivation and, therefore, the expansion and development of sustainable aquaculture in non-eutrophic marine waters.     

Finfish Mariculture in Inland Australia: A Review of Potential Water Sources, Species, and Production Systems

Secondary salinization has rendered over 100 million hectares of arable land throughout the world, and over 5 million hectares in Australia, unsuitable for conventional agriculture. The use of this land and associated water for mariculture is an adaptive approach to this environmental problem with many potential economic, social, and environmental benefits. In this article, we review three key technical aspects for the development of a finfish mariculture industry in inland Australia, namely the potential sources of water, the species suitable for culture, and the production systems available to produce them. Based on factors such as their quality, quantity, and proximity to infrastructure, the most appropriate water sources are groundwater obtained from interception schemes and waters from operational or disused mines. Pond‐based culture methods using these water sources have many specific advantages; however, few species can thrive in the wide range of seasonal water temperatures experienced within the temperate regions where secondary salinity is most abundant. Recirculating aquaculture systems (RAS) would enable production of more species in a greater number of water sources; however, the benefits typically associated with RAS are not as apparent in rural areas. Mulloway, Argyrosomus japonicus, are a temperate species that appear to have many positive attributes for inland mariculture; however, more data are required on their rate of growth across a wider range of temperatures. Seasonal production of barramundi, Lates calcarifer, in ponds has been demonstrated in the temperate climatic zones but may be more appropriate for those salinized water sources located in the warmer parts of the country. Freshwater species, such as silver perch, Bidyanus bidyanus, and Murray cod, Maccullochella peelii peelii, are likely to be suitable for low‐salinity waters. Rainbow trout, Oncorhynchus mykiss, also have excellent potential provided water temperature can be maintained below the upper lethal limit.     

The role of aquaculture in the sustainable development of irrigated farming systems in Punjab, Pakistan

Natural resource managers in Pakistan today preside over a massive investment in water distribution infrastructure. An historical bias towards large-scale irrigation systems and a focus on water use for arable crop production appears to have contributed to an imbalance in food production in the region. This has resulted in the diminished supply and elevated price of fish and meat products, compounded by the disruption of natural fisheries. The situation is inconsistent with the regions food security needs and an important potential role exists for increased aquaculture development. Physically and organizationally, the integration of various fish production approaches into existing land and water use practices would also appear to be fundamentally feasible. There would appear to be strong economic justification for diversified water use involving fish production, especially small and medium-scale carp production in ponds, using ground water. More broadly, within the context of the limited potential for further expansion of water resources, integrated aquaculture could contribute a vital productive element to various components of the water distribution arid irrigated farming systems in the Punjab. These include: supply canals, provided diverse institutional and engineering objectives can be accommodated; groundwater (including potential application of saline groundwater); the farm sub-system, especially integrated rice and fish production options in conjunction with alternative pest control strategies such as Integrated Pest Management; and irrigation drainage systems, where water quality permits. Therefore urgent broad research objectives should include the definition, investigation and development of a series of distinct economic and environmentally sustainable approaches to integrated animal protein production from aquatic resources, presently managed principally for agricultural production. Approaches should involve both the replacement of lost fishery potential resulting from large-scale irrigation development and flood control management, and the development of net gains in aquatic output, and should focus particularly on efforts to promote recycling of agricultural residues, reduced pesticide use and efforts to make better use of scarce water resources through the integrated aquaculture production across a broad range of water resources. An increasing number of countries are approaching full development of their surface water resources, and like Pakistan many face the development of new management approaches to increase diversity and improve productivity in relation to water use. The lack of research in support of the development of integrated aquaculture, which lags many years behind comparable agricultural research, may be constraining the breadth of choice available to natural resource managers to meet their food security needs.     

黑龙江省实施千亿斤粮食产能巩固提高工程的对策和措施

粮食是关系国计民生的重要商品,是关系经济发展、社会稳定和国家自立的基础,保障国家粮食安全始终是治国安邦的头等大事。黑龙江省是重要的粮食主产区和国家的商品粮基地,在全国占有十分重要的战略地位。黑龙江省要实施千亿斤粮食产能巩固提高工程,应采取建立健全各级政府的粮食安全责任法,确保耕地数量和质量,积极开展提高和恢复土地产能工程,科学规划并加强黑龙江省粮食生产布局和优质粮食产业带建设,开发盐碱地,建立粮食后备产区等对策和措施。     

PERI-URBAN OYSTER FARMING IN THE UPPER GULF OF THAILAND

Oyster farming is an important source of income in many coastal communities throughout Asia. Little is known, however, about the productivity of the farming systems used and the challenges faced by growers. This paper presents the results of a study undertaken in the small peri-urban coastal community of Ang Sila on Thailand's eastern seaboard. The community is located in one of Thailand's most important oyster production areas, and is dominated by small farms that use simple semi-traditional culture techniques. Farm attributes together with the personal characteristics and opinions of farmers were obtained from a survey of 30 oyster farm owners. A typical farm of 100,000 strings was found to produce a net profit of approximately 90,000 baht ($2250 USD). A high level of female participation in farm ownership was also identified that benefits women with relatively low levels of education and limited economic opportunities. Peri-urban coastal areas in Thailand cannot currently produce export quality shellfish owing to water quality concerns. Improved growing water management techniques and the introduction of seafood safety protocols could, however, improve the quality of oysters sold to domestic consumers and provide a basis for developing export opportunities in the future.     

生物絮团技术在水产养殖中的应用研究

传统的水产养殖模式所带来的环境污染、资源浪费和病害频发等问题已成为制约我国水产养殖业可持续发展的主要因素。生物絮团技术(BFT)具有净化水质、提高饵料利用率及病害防控等优点,被认为是有望解决上述问题的新型健康生态养殖技术,已在国内外得到一定规模的应用,并获得了良好的经济、社会和生态效益。本文重点介绍了生物絮团的形成与培养、生物絮团的主要影响因素及其在水产养殖中的应用效果。研究认为,BFT能够改良水质、节约养殖用水、降低饲料成本、提高养殖对象存活率、增加养殖产量和效益;将BFT与生物膜技术相结合,能够更有效地维持养殖水体中适宜的生物絮团含量,避免生物絮团的过量沉积,并能提高水质改良及增产增收的应用效果,具有广阔的应用前景。     

The effects of season, temperature and initial gonad condition on roe enhancement of the sea urchin Evechinus chloroticus

A series of 10-week experiments were repeated during the austral autumn, winter, spring and summer to investigate the seasonal effects, independent of seasonal temperature variation, on roe development (enhancement) of Evechinus chloroticus over a 12-month period and whether this differed among urchins with different initial gonad index (GI) values. E. chloroticus collected from wild populations with high and low initial GI values were caught and held in either ambient or constant ( 14.7 °C) seawater temperatures. The study has shown that, given a suitable roe enhancement diet, it is possible to significantly increase the GI of urchins throughout the year and that a seasonal effect on both the final GI and increase in GI, is primarily caused by seasonal variation in temperature. There are also significant effects from other factors, such as the initial condition of the animals prior to the trial and the reproductive stage of the urchins, but these are not as significant as the effects of temperature. The results indicate that it would be possible to increase the productivity of sea urchins by capturing them in cooler water and enhancing them at a site with relatively warmer water. The initial condition (GI) of the urchins plays an important role in gonad production with animals taken in low initial GI condition producing significantly larger increases in GI throughout each of the four seasons, than those with a high initial GI value. The urchins from the two populations developed through the stages of the reproductive cycle at a similar rate despite different final GI values and rates of increase in GI in both the temperature and population treatments, indicating that the differences in gonad production are related to environmental effects rather than the reproductive stage of the urchins. The exception to this occurred in the autumn samples where lower GI values and increase in GI were found during this season compared to in other seasons for the constant temperature treatment.

There is an overabundance of low GI urchins in the coastal waters of New Zealand and these animals are relatively easily found and fished on snorkel compared to high GI animals for which fishing pressure is much higher. It would appear to be more economic to fish and enhance low GI animals in New Zealand due to their relative abundance, ease of access and higher productivity during enhancement.     

Geography limits island small‐scale fishery production

Interacting social and ecological processes shape productivity and sustainability of island small‐scale fisheries (SSF). Understanding limits to productivity through historical catches help frame future expectations and management strategies, but SSF are dispersed and unaccounted, so long‐term standardized data are largely absent for such analyses. We analysed 40 years of trade statistics of a SSF product that enter international markets (sea cucumber) from 14 Pacific Island Countries and Territories (PICT) against response variables to test predictors of fishery production: (i) scale, (ii) productivity and (iii) socio‐economics. Combined production in PICT peaked over 20 years ago, driven by exploitation trends in Melanesia that accounted for 90% of all production since 1971. The size of island fisheries (as measured by total exports), and the duration and magnitude of fishery booms were most influenced by ungovernable environmental variables, in particular land area. The large and high islands of Melanesia sustained larger booms over longer periods than atoll nations. We hypothesize that land area is a proxy for land‐based nutrient availability and habitat diversity, and therefore the productivity of the shallow water areas where SSF are operating. PICT need to tailor management based on the intrinsic productivity of shallow inshore habitats: harvests from atoll nations will need to be smaller per unit area than at the high islands. Particularly countries with low productivity fisheries must consider the crucial economic “safety nets” that export SSF make up for dispersed island populations and incorporate them into broader development and island resilience strategies.