"With Earth's burgeoning population to feed we must turn to the sea with new understanding and new technology. We must farm it as we farm the land" - Jacques Cousteau 1973
Cousteau didn't explain what he meant by this. I'll try and explain today whait it means to me.
The Mexican tunafleet catches mainly yellowfin tuna and, to a lesser extent, skipjack tuna in thewarm waters of the eastern Pacific Ocean.These catches are primarily for canning. Ensenada usedto be the main tunafishery port in Mexico, and almost all of its production was exported to theUnited States.
A few years ago, thefleet moved to the southern ports of Mazatlan and Manzanillo, located closer tothefishing grounds and the major national markets, mainly Mexico City, Guadalajara and Monterrey.Thisfleet relocation negatively impacted the port of Ensenada, but bluefin tuna farming has beenestablished nearby as a lucrative added-value activity off the coast of Baja California. Wild tuna arecaught and stocked intofloating pens, where they are fed until they gain enough weight and fat tomeet market demands.
As a response to growing land and freshwater shortages and climate change, the use of seaweeds as food, their cultivation at sea and its effect on biodiversity are being researched on both the Caribbean and Pacific coasts of Costa Rica. Native species, more plentiful on the Caribbean coast, were collected and pre-selected based on existing information and on criteria including ubiquity, abundance, growth and palatability. These species were then evaluated as food and subjected to floating long-line cultivation using vegetative propagules. After establishing postharvest procedures, use as food involvedmany preparations to be eaten fresh or after drying, including a dry-ground meal. Ten of these species, which had nutrient contents within expected values including 9.8% crude protein on a dry weight (dw) basis and high iron, were considered adequate as food, both directly and as part of recipes in quantities not exceeding 20% dw of a given dish. Higher concentrations either ‘overwhelmed’ traditional recipes or their taste was rejected by tested consumers. Near-coast cultivation was in general a simple matter, easily transferred to artisanal fishers. To a great extent due to herbivory and theft of ropes, yield (ranging from 51.7 to 153.2 t ha−1 yr−1 on a fresh weight basis) was quantified for only five species with amean of 9.3 t ha−1 yr−1 dw, equivalent to 0.91 t ha−1 yr−1 of crude protein—very similar to yields of two grain crops per year. Species of Codium, Gracilaria, Sargassum and Ulva were considered adequate both for use as food and cultivation. Cultivated seaweed plots rapidly attracted biodiversity, including a significantly larger number of fish species and individuals than nearby control areas. Based on this we postulate the need to further explore a ‘biodiversity enrichment’ service from seaweed cultivation and any effect of this on fisheries enhancement. While noting areas in which further research and international collaboration are needed, it is concluded that tropical seaweeds, besides their many other uses, can at this stage substitute up to 15% of food on a dry weight basis, their cultivation is simple, and effects on biodiversity are a previously undocumented advantage. Given the lack of experience in most of the world excepting some Asian countries, the agriculture-like approach followed here may be of use to others in tropical developing countries who wish to explore seaweed cultivation at sea, for food and other products and for environmental/biodiversity services.
Seaplants such as macroalgae, microalgae, sea-grasses and mangroves form the primary productivity base for seashore habitats and integrated multi-trophic aquaculture (IMTA) systems. The foundation for sustainable seashore development is therefore the effective utilization, cultivation and management of seaplant populations.
In the long run the aquaculture productivity of global seashores can be maximized if seaplants are effectively developed as cash crops, feeds, fodder and bio-mitigation agents within IMTA systems that make optimal use of lower trophic-level species.
In the Coral Triangle 400 million people live in archipelagos that have 100,000 kilometres of tropical seashore distributed among more than 25,000 islands. About 80 million of these people live below the poverty line and many aspire to gain a sustainable livelihood from well managed seashore habitats.
IMTA development along Coral Triangle seashores can generate tens of billions of USD in annual income for micro, small and medium enterprises owned and operated by the coastal people of the Coral Triangle. IMTA can be developed on the basis of already existing technology, it addresses existing market demands, it can alleviate poverty for millions of people and it can generate positive environmental impacts. Stimulating adequate investment in this opportunity will generate substantial benefits that can be realised in the coming
decades.
Executive Summary
Performance assessment, regional tuning and validation of a software program known as AquaModel were the primary goals of this study. The software was designed for use by governments and industry to predict the sea bottom and water column effects of fish aquaculture. From an industry perspective, it also includes advanced tools to optimize fish production by obviating the usual trial and error method of configuring pen spacing and loading, by estimating optimum fish loading and culture density for growth in relation to currents and ambient oxygen supply.
The benthic submodel of AquaModel software was applied, tuned and validated at the Blue Ocean Mariculture LLC fish farm site near Kona on the big island of Hawai’i (herein “study site”). Fish production is relatively small at present and this factor, combined with the deep water location and moderately strong current velocity and variable directions of flow allows the organic wastes from the farm to be spread over a very large area and readily assimilated into the food web without perturbations. Seven years of field data from five locations was collected by an independent scientist who reports to the State of Hawaii government for this study. To more accurately simulate the fish farm waste production, AquaModel staff created the first physiological and growth model of the cultured fish, Seriola rivoliana (aka KampachiTM or Almaco jack) and tuned this submodel to produce the same growth patterns and food conversion ratios seen at the study site.
Model Overview
AquaModel is composed of interlinked submodels of fish physiology, hydrodynamics, water/sediment quality, solids dispersion and assimilation into the aquatic food web. The model simultaneously calculates and displays a time series of water and sediment quality conditions resulting from fish feed ingestion, fish growth, respiration, excretion, and egestion. The user is presented with a 3-dimensional video-like simulation of growth, metabolic activity of caged fish, associated flow and transformation of nutrients, oxygen, and particulate wastes in adjacent waters and sediments. The software is used by government managers and researchers in several locations worldwide and is presently being formally validated in Canada and Chile at five large fish farms. These validation activities have necessitated numerous upgrades and new utilities in AquaModel, some that are described herein.
New Fish Submodel
Solid wastes dynamics in the model are calculated from feed consumed and a small percent of waste, as well as the assimilation efficiency and food conversion ratio. These results were compared to measurements and estimates from the fish farmers as a quality assurance measure. A physiological model of the cultured fish species reared at Blue Ocean Mariculture (Seriola rivoliani, aka “KampachiTM”) was created for this project and tested to produce growth and food conversion efficiency results similar to that achieved at the farm site.
Circulation of Study Site and Prior Monitoring Results
Accuracy of aquaculture models is strongly related to the quality of the physical oceanographic inputs, particularly in open ocean conditions where non-tidal forcing factors result in considerable variation of flow rates and directions. Two months of continuous surface to bottom (ADCP) current meter records were collected every 20 minutes at the center of the net pen area lease. Surface currents above submerged net pen depth were strong, averaging about 28 cm s-1, but these subsurface readings were affected to some degree by backscatter from the water-air interface. Reliable current velocity readings were obtained from about 10 meters depth (top of submerged net-pen depth and below) to a few meters above the bottom averaging about 9 to 13 cm s-1 (SD range 7 – 9 cm s-1). Polar current vector diagrams produced by AquaModel indicated good dispersion flows in all directions with dominance to the northeast and southwest at net-pen depth and flowing mainly to north and south nearest the sea bottom. These characteristics indicate suitable conditions for rearing fish and provide regular resuspension of solid wastes on the sea bottom. Resuspension allows for aerobic assimilation of the waste feed and fish feces.
The sea bottom was composed of a thin, coarse-sand layer over hardpan and had very low background (reference station) total organic carbon concentrations (TOC) of about 0.14% (SD = 0.03) as measured over several years of monitoring. There were four reference areas sampled and one near-net-pen location from the center of the aquatic lease area. Field data suggested only a possible increase of about 0.1 to 0.2 %TOC near the center of the net pen locations to values of 0.15 or 0.16 %TOC (SD = 0.05), respectively. Statistical difference (p =0.035, df =6) was found comparing sediment TOC results of annual mean from a reference area to the center of the net pen area. No field data were available from sediments immediately adjacent to the net pens but the model produced estimates for all locations.
Modeling Challenge
Because of the naturally low organic carbon content of the sea bottom and the relatively small size of the fish farm and the limitations of a single net pen area sampling location, it was not certain at the outset that the model could produce reasonable results. Typically, aquaculture models are used at or for planning of fish farms that may be much larger than the Blue Ocean Mariculture project. Most other farms are located in shallower water, sometimes with lesser current velocity and this produces a strong benthic-effects signal. Therefore, the signal to noise ratio is high for these other farms, but low by a factor of about 5 to 10 or more for the study site. The model was set up to grow concurrent crops of KampachiTM in each cage to a total fish biomass of 590 metric tons, slightly exceeding previous annual production. Figure 1 illustrates one of thousands of frames of the video-like output that the model produces. This one is from near the end of the fish production simulation with maximum fish biomass. The color scale in Figure 1 was adjusted to show an extremely low range of TOC concentrations. Solid green color indicates values of about 0.18 %TOC or about 0.04 %TOC above background, a difference that is similar to the normal error range of a high-precision laboratory analysis.
Model Performance
After calibrating and tuning the AquaModel to regional conditions, it produced background (reference) conditions within >0.001 %TOC of measured, steady-state reference-station values. This is essentially no difference between modeled and measured and certainly not with respect to measurable outcomes in the field. This is noteworthy as other benthic aquaculture models have been unable to maintain background organic carbon steady state concentrations due to resuspension washing TOC out of their modeling domains. With AquaModel, best estimates of the results at the single sampling station nearest the net pens were within<0.0012 %TOC of measured, long-term average results for the best-tuned setup. AquaModel consistently produced slightly higher sediment TOC concentration estimates (<0.02% TOC) at other locations nearer the two largest pens that had no corresponding field data measurements to verify the model predictions at these locations. All of the >250 simulations performed for this study indicated the same spatial pattern of increased TOC, with differing values depending on the calibration settings. None of the TOC concentrations measured or modeled indicated any risk of sea bottom eutrophication or probable significant biological change.
Validation Outcome
This study indicates that the tuned and validated AquaModel program should be sufficiently robust to model other open ocean locations of the leeward shores of the Hawai’ian Islands. The model is designed to work effectively with much higher levels of sediment organic carbon loading from fish farms, but not at grossly eutrophic cage sites in some sheltered, inshore cage locations utilized decades ago. AquaModel use would readily identify such outcomes through observation of several parameters, such as TOC delivery rate to the bottom (“TOC Rate”, in grams carbon per m2 per day) as well as sediment interstitial oxygen and sediment sulfides results. With separate cages that are spaced appropriately, most open ocean locations on the leeward shores of the Hawai’ian Islands that are in sufficient depth of water would not produce eutrophic or even modestly elevated sediment conditions. However, some habitats are considered of special biological significance, where net pen siting should not be considered.
Overview and AquaModel Use in Hawai’i
This evaluation, along with the existing routine monitoring program at the subject site as well as other analyses cited herein, indicate that the fish farm operation is not adversely affecting benthic conditions in the area. The waste tracking utilities of AquaModel applied to this particular site indicate that a small fraction of the waste fish feces reaches locations outside the modeling domain. The estimated loading rate of organic carbon in those locations are so minimal at present that it produces no measurable or even modeling-predicted change in concentration of sediment TOC. The chance of changing the biology of the benthos at these same locations is therefore highly unlikely. In general, small amounts of TOC added to the sea bottom from any source in the marine environment have been found to increase biodiversity and abundance of benthic organisms, but often at nearshore fish farms, these levels are exceeded. AquaModel provides a convenient and relatively accurate means of estimating future carrying capacity for this farm or groups of farms in the future. It also should be used to inform future monitoring efforts, rather than selecting sampling locations through best guess or randomly. Now that regional tuning is complete, configuring and running the model is not difficult for other locations similar to the west coast of the Big Island of Hawai’i and in other similar habitats throughout the region.
AquaModel validation continues at other sites around the world that are larger in fish biomass and more replete with measurement locations in the field. Optimum model calibrations or trends identified in this study were in many cases as expected and occurred in other model validation locations. These findings, combined with prior model use experience and published literature guidance gives us confidence that the validation procedure employed herein is not a product of simple coincidence.
Several.concepts have been developed for tropical marine biomass cultivation for bioconversion to methane. These concepts take advantage of Florida's large areas of relatively shallow water. One concept, tidal flat seaweed farms, uses currently available macroalgal candidates (Gracilaria, Ulva) and at biomass yields of 12-25 dry ash free tons/hectare-year can-provide delivered low feedstock costs of · $40-25/DAFT, or on an energy basis, $3.60-2.30/G joule, respectively. These biomass yields are close to those achieved in commercial Gracilaria culture in Taiwan. Such systems would be constrained to nearshore waters of 0.5-1.5 m in depth, of which there are 190,000 hectares in northwestern Florida.
Concepts which would work in deeper waters (from 1.5-20 m depths) use floating seaweeds. Such biomass species would need to be produced by genetic breeding and hybridization, as there is not an adequate natural species available which also has high bioconversion rates. Such hybrids may be intrageneric ones of Sargassum, or Sargassum hybrids with other algae such as Macrocystis. A biotechnology approach could provide competitive feedstock costs with a large potential gas production, as there is approximately 1,900,000 hectares between 1.5-20 m depths in northwestern Florida.
Gracilaria is a group of warm water seaweeds. There are more than one hundred species in the world, some of which have very important economic value. Gracilaria is used as food and in the preparation of food products. It is also an important raw material in agar-agar production. At present, the world's annual output of Gracilaria is about 30,000 tons, dry weight, most of which comes from natural production. For example, the natural production in Chile, Argentina, and Brazil accounts for one third of this total output. With the increasing demand for Gracilaria, greater attention has been focused on the development of its artificial culture by many countries, especially those in Southeast Asia. China is the earliest country that artificially cultured Gracilaria. Today, the culture area in South China is about 2,000 ha producing 3,000 tons dried material annually. Taiwan produces 1,000 tons dried Gracilaria yearly from 400 hectares under cultivation.
Nowadays, Gracilaria is cultured mainly using the following methods: bottom culture, raft culture, stake-rope culture and pond culture. Pond culture can be divided into two systems, monoculture and polyculture with shrimp and other species. The varieties of culture methods can be adapted for different areas.
In view of the importance of Gracilaria as a seafarming commodity, the National Coordinators of the Regional Seafarming Project recommended the dissemination of its culture and processing technology, through a regional training and demonstration activity, as a means to further increase the opportunities to develop the seafarming industry of the region.
This manual has been prepared for the training course on Gracilaria culture under the Regional Seafarming Development and Demonstration Project (RAS/90/002) to be held at Zhanjiang Fisheries College, Zhanjiang, China in August, 1990. The training course includes processing of seaweeds, thus the manual devotes a chapter on the properties, manufacture and application of agar, algin and carragenan.
The manual was edited by Professor Wu Chaoyuan who also reviewed all the manuscripts, Professor Ji Minghuo, Mrs. Li Renzhi, Associate Professor and Mr. Wang Xiaohang, Associate Professor, all of the Institute of Oceanology in Qingdao; Professor Liu Sijian of the Zhenjiang Fisheries College; and Mr. Miao Zenian, Associate Professor of the Yellow Sea Fisheries Research Institute, Qingdao. Mr. Sun Jimin of the Yellow Sea Fisheries Research Institute computer-processed the text and images. The staff of the Seafarming Development Project in Bangkok provided the final editing and prepared the manual for publication.
We would like to acknowledge the support of the Intergovernmental Network of Aquaculture Centres in Asia and the Pacific (NACA), the Institute of Oceanology of Academia Sinica, the Yellow Sea Fisheries Research Institute under the Chinese Academy of Fishery Sciences, and the Zhanjiang Fisheries College in the organization and implementation of the training course including the development and publication of this manu
Integrated Multi-Trophic Aquaculture (IMTA) systems are designed to mitigate the environmental problems caused by several forms of fed aquaculture. Gracilaria chilensis is commercially cultivated in Chile and experimental studies recommend it as an efficient biofilter in IMTA systems. Traditional bottom culture Gracilaria farms face production problems mainly related to the cultivation system and seasonal changes in nitrogen availability and irradiance. IMTA may offer a solution to some of these problems.
This study intended to investigate the productivity of G. chilensis near salmon farms and assess its nitrogen removal and photosynthetic performance. The most appropriate cultivation methodologies (i.e. floating long-lines vs. bottom cultivation) for Gracilaria production were also evaluated. During austral summer and autumn, 3 long-line cultivation units were set at different distances from a salmon farm, one of them being away from the influence of salmonid aquaculture. Additionally, a similar cultivation unit was installed as a traditional bottom culture.
Gracilaria growth performance was always higher on the suspended cultures near the salmon cages. Summerdaily mean growth rates at those sites reached 4% (±0.29) with a mean biomass production of over 1600 gm−2 month−1(±290) which was double the unimpacted site. The productivity of bottom cultured Gracilaria was highly reduced by biomass losses. N removal and photosynthetic performances provided possible explanations for the differences found. The long-line cultivation unit proved to be the most efficient technology for nutrient removal with monthly removal of up to 9.3 g (±1.6) N per meter of long-line.
The proximity to the salmon farm also mitigated the decrease in photosynthetic activity after the midday irradiance peak. G. chilensis at those sites maintained daily average values of ΦPSII around 0.6 and rETR close to 40 μmol e− m−2 s−1. Fv/Fm values (0.6) were similar at all cultivation areas. Our results clearly indicated the advantages of integrating G. chilensis aquaculture with salmon farms. Within the IMTA system, the productivity and physiological performance of G. chilensis ere greatly improved and this seaweed's biofiltration efficacy was confirmed. We suggest that a 100 ha G. chilensis long-line systemwill effectively (ca. 100%) reduce the N inputs of a 1500 tonnes salmon farm.
With the increase in the world’s population, demand for food and other products is continuously rising. This has put a lot of pressure on the agricultural sector. To fulfill these demands, the utilization of chemical fertilizers and pesticides has also increased. Consequently, to overcome the adverse effects of agrochemicals on our environment and health, there has been a shift towards organic fertilizers or other substitutes, which are ecofriendly and help to maintain a sustainable environment. Microalgae have a very high potential of carbon dioxide (CO2) capturing and thus, help in mitigating the greenhouse effect. It is the most productive biological system for generating biomass. The high growth rate and higher photosynthetic efficiency of the algal species compared to the terrestrial plants make them a wonderful alternative towards a sustainable environment. Moreover, they could be cultivated in photobioreactors or open ponds, which in turn reduce the demand for arable land. Biochar derived from algae is high in nutrients and exhibits the property of ion exchange. Therefore, it can be utilized for sustainable agriculture by partial substituting the chemical fertilizers that degrade the fertility of the soil in the long run. This review provides a detailed insight on the properties of algal biochar as a potential fertilizer for sustainable agriculture. Application of algal biochar in bio-refinery and its economic aspects, challenges faced and future perspective are also discusses in this study.
Selaru Island community has long ago been familiar with activity of fulfilling needs through Tnyafar. Being a local wisdom, every household used Tnyafar as a livelihood strategy. Through Tnyafar, community exploited natural resources regularly to ensure the fulfillment of the needs. This research was aimed to analyze community activity that based on local wisdom and to understand the position of local wisdom in the process of fulfilling needs. Research used qualitative approach. Data collection technique involved depth interview and focussed group discussion. Informants were selected with Snowball Technique with land-owner as key informants. Other informants included Tnyafar Chief, Village Chief, and Tnyafar members either men or women. Result of research indicated that Tnyafar was a local wisdom expression in small island that takes into account the limited natural resources as the inheritance for the next generation. Also through Tnyafar, community did work activity together to ensure the fulfillment of needs. All the needs including food, cloth and shelter were fulfilled through the work output at Tnyafar.
Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
Contact: Marine.Agronomy.Group@gmail.com
Funding for this web portal is provided by the World Wildlife Fund and the University of Hawaii-Hilo.
