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This document contains the proceedings of the technical workshop entitled “Expanding mariculture: technical, environmental, spatial and governance challenges”, held from 22 to 25 March 2010, in Orbetello, Italy, and organized by the Aquaculture Branch of the Fisheries and Aquaculture Department of the Food and Agriculture Organization of the United Nations (FAO). The objective of this workshop was to discuss the growing need to increasingly transfer land-based and coastal aquaculture production systems farther off the coast and provide recommendations for action to FAO, governments and the private sector. The workshop experts proposed general “operational criteria” for defining mariculture activities in three broad categories: (i) coastal mariculture, (ii) off the coast mariculture and (iii) offshore mariculture. Offshore mariculture is likely to offer significant opportunities for food production and development to many coastal countries, especially in regions where the availability of land, nearshore space and freshwater are limited resources. Mariculture is also recognized as a relevant producer of the protein that the global population will need in the coming decades. It is likely that species with the highest production today, such as salmon, will initially drive the development of offshore mariculture. Nevertheless, the workshop agreed that additional efforts are necessary to define optimal species and improve efforts in the development and transfer of technologies that can facilitate offshore mariculture development. The workshop discussions and reviews indicate large potential for the development of offshore mariculture although more detailed assessments are needed to determine the regions and countries that are most promising for development. It is also recommended that efforts be increased to farm lower trophic levels species and optimize feeds and feeding in order to minimize ecosystems impacts and ensure long-term sustainability. Similarly, risk assessments and/or environmental impact assessment and monitoring must always be in place before establishing offshore farms, and permanent environmental monitoring must be ensured. All coastal nations should be prepared to engage actively in developing the technological, legal and financial frameworks needed to support the future development of offshore mariculture to meet global food needs. The workshop report highlights the major opportunities and challenges for a sustainable mariculture industry to grow and further expand off the coast. In particular, the workshop recommended that FAO should provide a forum through which the potential importance of the sea in future food production can be communicated to the public and specific groups of stakeholders and to support its Members and industry in the development needed to expand mariculture to offshore locations. The proceedings include the workshop report and an the accompanying CD–ROM containing six reviews covering technical, environmental, economic and marketing, policy and governance issues, and two case studies on highfin amberjack (Seriola rivoliana) offshore farming in Hawaii (the United States of America) and one on salmon farming in Chile.
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With increasing interest in feed based methane mitigation strategies, fueled by local legal directives aimed at methane production from the agricultural sector in California, identifying local sources of biological feed additives will be critical in keeping the implementation of these strategies affordable. In a recent study, the red alga Asparagopsis taxiformis stood out as the most effective species of seaweed to reduce methane production from enteric fermentation. Due to the potential differences in effectiveness based on the location from where A. taxiformis is collected and the financial burden of collection and transport, we tested the potential of A. taxiformis, as well as the brown seaweed Zonaria farlowii collected in the nearshore waters off Santa Catalina Island, CA, USA, for their ability to mitigate methane production during in-vitro rumen fermentation. At a dose rate of 5% dry matter (DM), A. taxiformis reduced methane production by 74% (p ≤ 0.01) and Z. farlowii reduced methane production by 11% (p ≤ 0.04) after 48 hours and 24 hours of in-vitro rumen fermentation respectively. The methane reducing effect of A. taxiformis and Z. farlowii described here make these local macroalgae promising candidates for biotic methane mitigation strategies in the largest milk producing state in the US. To determine their real potential as methane mitigating feed supplements in the dairy industry, their effect in-vivo requires investigation.
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The use of seaweed as feed ingredient is gaining interest but the high ash content, low nutrient digestibility, short shelf life and poor economic feasibility hamper practical application. This study investigates the effect of washing, ensiling and extraction processes on the nutritional value of seaweed products for broilers, based on nutrient content and in vitro and in vivo digestibility. The effects of ensiling, washing and extraction processes were evaluated using Saccharina latissima, Laminaria digitata and Ulva lactuca, with 2, 4, and 6 h incubations in an in vitro simulated digestibility model, to obtain insight into the kinetics of digestibility. In an in vivo study, 160 Ross 308 male broilers were fed (day 14–22) a basal grower diet, or the basal grower diet with 100 g/kg of S. latissima silage or silage residue. Performance and ileal and total tract nutrient digestibility were determined. Washing and ensiling reduced the ash content, but also the in vitro organic matter digestibility (both P < 0.001). Washing also reduced nitrogen digestibility (P < 0.001). Extraction of seaweed decreased in vitro organic matter and nitrogen digestibility. Feeding seaweed diets to broilers resulted in a higher feed conversion ratio (1.62 versus 1.86 and 1.77 for broilers fed the basal, silage and silage residue diets respectively, P < 0.001) without increase in final body weight. Feeding S. latissima silage residue compared to silage resulted in a slightly better broiler performance and a higher amino acid digestibility. In conclusion, washing, ensiling and extraction processes reduce the nutritional value of the seaweed products, and do not make seaweed suitable for inclusion in broiler diets. To create suitable seaweed products for inclusion in broiler diets, a further reduction in the ash content and increase in digestibility is needed.
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In the US, seaweed aquaculture is still a developing industry. Since a significant number of seaweed farms are located in urbanized estuaries, cultured seaweeds could accumulate contaminants such as heavy metals. A warm temperate red algal species, Gracilaria tikvahiae and a cold-water brown algal species, Saccharina latissima were cultivated at three sites in Long Island Sound (LIS) and New York (NY) estuaries to biomonitor potentially toxic metals. Metal concentrations were below almost all national and international regulatory limits for human consumption. For example, the highest measured concentrations of Hg in tissue samples of G. tikvahiae and S. latissima are 88–93% less than the limit set by the Food and Drug Administration of the USA. Concentration maxima of Cd in G. tikvahiae and S. latissima were 20% and 32%, respectively, lower than stringent French limits. Maximum levels of Pb in tissue samples of G. tikvahiae (but not S. latissima) were close to the French limits at the NY estuary site. These results indicate generally that heavy metal contents of seaweeds cultivated urbanized estuaries should be monitored since accumulation appears to be site-dependent. The great capacity for the accumulation of nitrogen and other nutrients in seaweed tissues, improving water quality, is also accompanied by the uptake of other, less desirable materials.
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In this study, Saccharina japonica was treated with pressurized hot water extraction (PHWE) at a temperature of 180 °C–420 °C and pressure between 13 bar and 520 bar. The obtained hydrolysate was investigated for their yield, total organic carbon (TOC), pH, Maillard reaction products, viscosity, color, and amino acid, mineral, and monosaccharide contents. The extraction yield increased with an increase in temperature and varied from 72.21% to 98.91%. TOC, pH, and potassium and sodium content increased, whereas viscosity decreased, with an increase in temperature. Essential amino acids such as valine and lysine and non-essential amino acids such as aspartic acid, glutamic acid, glycine, and tyrosine recovered well at low temperature. The content of heavy metals such as arsenic, cadmium, mercury, and lead was very low in the obtained hydrolysate. The maximum amount of total amino acids was recovered at 180 °C/13 bar (761.95 ± 14.54 mg/g). The level of main monosaccharides such as glucose (6.70 g/L), fructose (8.40 g/L), and mannitol (17.50 g/L) was found to be very high at 180 °C/13 bar. The results indicated that the pressurized hot water extract of S. japonica has good potential for use in the fermentation industry and can be used as human food.
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Rates of inorganic nitrogen uptake by three Northeast US and three Asian species of Porphyra were compared in short-term incubations to evaluate potential for longer term and larger scale examination of bioremediation of nutrient-loaded effluents from finfish aquaculture facilities. The effects of nitrogen (N) species and concentration, temperature, acclimation history, and irradiance were investigated. Uptake rates increased ca. nine-fold from 20 to 150 μM N. Nitrate and ammonium uptake occurred at similar rates. Irradiance had a strong effect, with uptake at 40 μmol photons m−2 s−1only 55% of uptake at 150 μmol photons m−2 s−1. N-replete tissue took up inorganic nitrogen at rates that averaged only 60% of nutrient-deprived tissue. Although there were species (P. amplissima > (P. purpurea = P. umbilicalis)) and temperature effects (10 C>5 C>15 C), interactions among factors indicated that individual species be considered separately. Overall, P. amplissima was the best Northeast US candidate. It took up ammonium at faster rates than other local species at 10 and 15 C, two temperatures that fall within the expected range of industrial conditions for finfish operations.
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Redclaw aquaculture has developed at a rapid pace during the past few years, yet no specialized diet for the species has been developed. The present study was designed to evaluate whether soybean-based diets containing either fishmeal (FM), poultry by-product meal (PBM), ground peameal (GPM) or distillers dried grains with solubles (DDGS) meal as a protein source are suitable for redclaw aquaculture. Juvenile redclaw crayfish Cherax quadricarinatus (0.125±0.025 g) were stocked into 20 rectangular tanks at a stocking density of 12.5 m−2 for 8 weeks. Crayfish in four replicate tanks were maintained on one of five diets formulated to contain 35% crude protein and 7.1% lipids. Each 100 g of diet contained 25 g of protein from soybean meal (SBM) and 10 g of protein from the alternative protein sources mentioned above. A fifth treatment that did not receive feed was included to account for growth from natural productivity. There were no significant differences in survival (86–90%), growth (3.84–4.98 g animal−1) or feed conversion ratio (2.10–2.79) of crayfish among the four treatments (P>0.05). Survival and growth of crayfish in the treatment that received no supplementary feed were significantly less than those in treatments offered experimental diets. Results of the present experiment suggest that SBM-based diets with PBM, FM, DDGS or GPM have similar effects on growth performance and survival of juvenile redclaw, C. quadricarinatus.
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Five bacterial strains were isolated for primary screening to test the phosphate solubilizing activity fromseaweed fed earthworm gut and seaweed vermicompost. The selected three bacteria were tested for phosphatesolubilizing activity in Pikovskaya’s broth amendedwith 250mg of TCP. Among the bacteria, maximum phosphatesolubilization was observed in B. licheniformis i. e., 795.3 ±10.5μg/ml. 16S rRNA sequence of most efficient bacteria,Bacillus licheniformis strain APSAC 04 was deposited inthe NCBI Gen bank with the following accession numberKY886136 for further retrieval and comparison.
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It is important to accurately evaluate the wellbeing or nutritional condition of organisms when monitoring the wild stock conditions and improvement in aquaculture techniques; however, reliable nutritional condition indexes have not been established for sea cucumbers. In this study, the effects of starvation on condition factor (body weight / body volume), coelomic fluid constituent (protein, carbohydrate and cholesterol) concentrations and coelomic fluid density were analysed in an attempt to establish a method to determine nutritional condition in juvenile sandfish (Holothuria scabra). Body length, breadth and weight of juveniles produced at the sea cucumber hatchery of the Aquaculture Department, Southeast Asian Fisheries Development Center, were measured after anaesthetisation with 2% menthol-ethanol. Coelomic fluid protein level was analysed by the bicinchoninic acid method. Carbohydrate level was analysed by the phenol – sulfuric acid method. Cholesterol level was analysed by the Zak method. Coelomic fluid volume and coelomic fluid weight were measured. Starvation caused a concomitant decrease in body length, breadth and weight, resulting in no net change in the condition factor. This result indicated that condition factor cannot be used as a nutritional condition index. Coelomic fluid constituent level could be measured with a small volume of sample (i.e. 10–20 µL). Although no clear pattern was observed in coelomic fluid protein and cholesterol levels during the starvation trial, carbohydrate level increased, as did coelomic fluid density. These results suggest that coelomic fluid density and carbohydrate level may be used as indexes for nutritional condition of sandfish without sacrificing the animal.
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Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
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