Economics of fish farming in Saudi Arabia: Analysis of costs of tilapia production

Abstract

Because Saudi Arabia is a substantial importer of fish and its capture fishery is operating beyond maximum sustainable limits, it has a special interest in developing fish farming. It has been encouraging tilapia production. This study examines the costs of tilapia farming in the Central Region of Saudi Arabia using cross sectional data from 23 intensive fish farms. It provides information about the relative importance of different cost items such as variable costs and feed costs in total costs. Also, cost functions are estimated by ordinary least squares and a cubic cost function is found to provide the best fit to the available data. Minimum average cost of production occurs for 201 tonnes of tilapia per year per farm and profit is maximised for a production of 300 tonnes annually per farm. All farms operate at less than profit‐maximising scale and most operate at less than minimum efficient scale. The reasons could be low quality fry, low levels of management expertise in culturing tilapia and the secondary nature of tilapia farming. Lack of water is likely to limit future expansion of tilapia farming in Saudi Arabia.     

THE SUSTAINABLE LIVELIHOODS APPROACH TO THE DEVELOPMENT OF FRESHWATER PRAWN MARKETING SYSTEMS IN SOUTHWEST BANGLADESH

A conceptual framework, drawn from an approach to poverty reduction known as the Sustainable Livelihoods Approach (SLA), is applied to understanding the role of freshwater prawn (Macrobrachium rosenbergii) marketing systems in southwest Bangladesh. Freshwater prawn marketing potentially provides economic returns and social benefits to the rural poor. Although the potential benefits are great, a number of constraints were identified for the long-term sustainability of prawn marketing systems. The study used the SLA framework as an analytical tool to identify ways to strengthen livelihoods of prawn traders and associated groups.     

DISAGGREGATED ANALYSIS OF FISH SUPPLY,DEMAND, AND TRADE IN ASIA: BASELINE MODEL AND ESTIMATION STRATEGY

ABSTRACT

Quantitative modeling of fish supply, demand and trade is a useful tool for analyzing recent structural changes, such as the rapid development of aquaculture. Existing models are, however, limited by their use of highly aggregated fish categories and assumed (rather than estimated) elasticities. This paper outlines an estimation strategy and a multiproduct equilibrium model for disaggregated analysis of fish supply, demand, and trade. The model is composed of a producer, consumer and trade core, and is specified to accommodate special features of the fish sector. The estimation and modeling strategy also address common data problems, such as heterogeneity of fish types, diversity of production categories, and so forth. The model has been applied to nine major fish producers in developing Asia.     

Review of infectious agent occurrence in wild salmonids in British Columbia,Canada

Wild Pacific salmonids (WPS) are economically and culturally important to the Pacific North region. Most recently, some populations of WPS have been in decline. Of hypothesized factors contributing to the decline, infectious agents have been postulated to increase the risk of mortality in Pacific salmon. We present a literature review of both published journal and unpublished data to describe the distribution of infectious agents reported in wild Pacific salmonid populations in British Columbia (BC), Canada. We targeted 10 infectious agents, considered to potentially cause severe economic losses in Atlantic salmon or be of conservation concern for wild salmon in BC. The findings indicated a low frequency of infectious hematopoietic necrosis virus, piscine orthoreovirus, viral haemorrhagic septicaemia virus, Aeromonas salmonicida, Renibacterium salmoninarum, Piscirickettsia salmonis and other Rickettsia-like organisms, Yersinia ruckeri, Tenacibaculum maritimum and Moritella viscosa. No positive results were reported for infestations with Paramoeba perurans in peer-reviewed papers and the DFO Fish Pathology Program database. This review synthesizes existing information, as well as gaps therein, that can support the design and implementation of a long-term surveillance programme of infectious agents in wild salmonids in BC.     

Effects of different carotenoid supplementation sources with or without sodium taurocholate on growth,feed utilization,carotenoid content and antioxidant status in fry of the European seabass,Dicentrarchus labrax

A total of 210 European seabass fry with an average body weight of 0.51 ± 0.03 g were divided into seven experimental treatments (three replicates per treatment). The seven experimental diets (45.64% CP) were formulated to contain synthetic astaxanthin (SA; 0.1 g kg^?1), marigold flower meal (MFM; 0.2 g kg^?1) or crab waste meal (CM; 10 g kg^?1), with or without sodium taurocholate (ST; 0.4 g kg^?1); the control diet contained no supplementation. The experiment was conducted for 8 weeks. The results show that seabass fry fed the diets containing different sources of carotenoids, especially with ST, demonstrated higher growth efficiency, survival (%), feed efficiency, protein and ether extract contents of fish body. The best results were found with Diet_MFM+ST. Whole‐body carotenoid levels increased significantly with all supplementation treatments; the highest level was observed with SA, followed by fish fed Diet_MFM and Diet_CM, especially with ST co‐supplementation. Moreover, thiobarbituric acid‐reactive substances were significantly reduced in fish fed the diets containing different sources of carotenoids compared to the control diet. The total antioxidant status significantly increased in fish fed Diet_SA and Diet_CM alone or with ST compared to the control group. In conclusion, these results reveal that Diet_MFM+ST is the most suitable treatment for improving growth, feed efficiency, and the protein and ether extract contents of seabass fry compared to other sources of carotenoids. The best oxidant/antioxidant balance and carotenoid content were achieved using SA, CM and MFM with ST supplementation.     

Potential applications of biological filtration media in changing water properties and subsequent effects on common carp (Cyprinus carpio) in recirculating aquaculture systems

This work aims to develop a suitable aquaculture system to solve issues pertaining to water quality in recirculating aquaculture systems (RAS) thereby improving fish growth performance and their feed conversion ratio (FCR). It is known that the efficiency of nutrient decomposition depends on the amount and species of bacteria present in the filter, and these can in turn be regulated by the pH. Our study shows that the significant increase in pH from 7.45 to 7.51 and 7.47 is achieved after the water was filtered through sawdust and wood wool respectively. At the same time, nitrite concentrations were found to have significantly decreased from 0.06 ppm in the control to 0.01 ppm in the sawdust treatment. Changes in the physical–chemical properties of treated water affect the biological properties of the organisms. It was found that the average final body weight for fish in the wood wool treatment 30.96 g and fish in the sawdust treatment 31.44 g was significantly higher compared to that for the fish in the control treatment 28.42 g. The use of sponge, wood wool or sawdust resulted in significantly lower FCR and therefore better fish productivity in RAS. At the same time, the red blood cell count, plasma urea, plasma creatinine, plasma albumin, and GOT and GPT were significantly higher in fish in the plastic, sponge, wood wool or sawdust treatment compared to the control treatment. In summary, this study demonstrates the benefits of using sponge, wood, wool and sawdust as biofilter media for aquaculture.     

Leptin inhibits mitogen-induced proliferation of peripheral T lymphocytes from Holstein cows

This study examined the mitogenic response of bovine peripheral T lymphocytes to leptin, a pleiotropic hormone regulating food intake and energy expenditure. Leptin alone slightly suppressed proliferation of T lymphocytes in the presence of concanavalin A (ConA). Leptin also inhibited proliferation of T lymphocytes induced by anti-CD3 antibody. ConA treatment activated some protein kinases, including p44/p42(MAPK) and Akt/PKB, while anti-CD3 antibody treatment increased mRNA expression of suppressor of cytokine signalling (SOCS) 3, interferon (IFN)gamma, interleukin (IL) 2 and IL4 in T lymphocytes. Leptin alone increased only SOCS3 mRNA expression. Simultaneous treatment with mitogens and leptin enhanced IFNgamma mRNA expression but decreased IL2 mRNA expression, without any synergistic effect on phosphorylation of protein kinases or mRNA expression of SOCS3 and IL4. These results suggest that leptin modulates bovine T lymphocyte functions.     

In vitro culture of mouse preantral follicles using membrane inserts and developmental competence of in vitro ovulated oocytes

To develop a reliable follicle culture system, mouse preantral follicles 150-200 microm in diameter were cultured individually for 5 or 6 days in membrane inserts or in droplets, and then induced to ovulate with hCG (Experiment 1). The nuclear maturation and developmental competence of the oocytes that ovulated from the follicles cultured in inserts were determined (Experiment 2). There was no significant difference between the two culture systems in the survival rate (83 and 77%). However, follicles cultured in inserts showed a higher ovulation rate (63%) than those cultured in droplets (39%, P<0.05). About 80% of the oocytes that ovulated from the follicles cultured in inserts were at the metaphase II stage. After in vitro fertilization, 75 and 48% of in vitro ovulated oocytes cleaved and developed into blastocysts, respectively. These results demonstrate that the insert culture system is superior to the droplet culture system in terms of follicular growth and ovulation, and can be used to investigate the growth and ovulation of follicles in vitro.     

Growth Responses of Maize Plants Cultivated in Sandy Soil Amended by Different Superabsorbant Hydrogels

The growth responses of maize plants cultivated in sandy soil amended with five different superabsorbent hydrogels were studied. Soil amended by superabsorbent hydrogels could enhance growth of maize and the level of enhancement was concomitant with the rate of the added hydrogel. Morphologically, plants grown in soil with the highest concentration of hydrogel (0.4%) were healthier and taller, and root lengths were longer. Fresh and dry weights were increased. Addition of hydrogel could improve water availability in the soil, so that water contents were higher in plants grown in the amended soil compared with those of control. Although maize growth was enhanced by the addition of any hydrogel, plants showed different responses to different hydrogels. The used hydrogels were beneficial in newly reclaimed deserts that suffered from drought stress conditions.