Page updated May 18th, 2019.
COMMONSEAGOOD, my project for our Mother Sea.
WHY it should be done. There are two good reasons to proceed.
First, because we have to find new food resources: for the soon to be 9 billion individuals, our food production needs to increase drastically. It is easily understandable that broad spare areas and quality water in quantity is the least we will need. On the contrary, as desertification and urbanization progresses, available arable lands shrink dramatically. Remaining forests and wild lands are either highly coveted or already acquired. Fresh water is hit by scarcity or pollution, and most of the coastal seas are not even free for new exploitations anymore.
So where are there still enough space and water? On HIGH SEAS !
Secondly, we need to keep the oceans resources (and us) healthy: Oceans fish resources are overexploited. For several years now, despite the fisheries' technical efforts, going always further and deeper, the wild capture production stagnates. Nevertheless, total production is increasing thanks to aquaculture, which grows so rapidly, that it is going to overtake capture production.
(Source: FAO, The state of world fisheries and aquaculture 2018)
The inland farming of herbivorous fish (carps, tilapias) is still able to increase as long as appropriate locations can be found on land, but the marine farming of carnivorous fish (salmon, bass, cobia) or shrimp is on the wrong track. In the context of its global expansion, this food system bites its own tail, as wild forage fish is necessary for feeding, and is unfortunately lacking more and more. Therefore, the fish farming industry tries to reduce and substitute its contribution in their feed. The ongoing attempts to feed farmed carnivorous marine fish with terrestrial agricultural resources, instead of fish meal and fish oil, may work technically, but make us actually lose all the benefits of a healthy fish, and so, healthy food for us.
Indeed, marine proteins are healthy because, set apart their good amino-acid profile, vitamins, minerals and trace elements, they present high levels of long chain omega 3 polyunsaturated fatty acids (LC-PUFA), well known to develop our brain and protect our heart and eyesight. Fishes, as all aquatic organisms, need a very large amount of these omega 3 in their diet, as they are the fundamental component of all their cell membranes. These essential LC-PUFA are nearly exclusively produced by phytoplankton, the first marine trophic level, which is assimilated by zooplankton, which is assimilated by forage fish, and so on. Without an appropriate amount of LC-PUFA, fishes are much more sensitive to stress, undergo diseases, and have more difficulties to bear with parasites like sea lice. In most aquaculture plants, in order to grow fish properly despite those issues, feed has to be complemented with antibiotics and the water treated with pesticides, which are both ultimately ingested by us. After some relevant scandals, the fish farming industry seeks to improve its methods with vaccines instead of antibiotics and lumpfish (sea lice eating fish) or mechanical treatments, instead of pesticides. Other ways of ongoing improvements are to go further offshore, where the stronger currents can sweep the pollution away, or to filter the water in recirculating aquaculture systems (RAS) on land. But the main problem remains the low LC-PUFA level in aquafeed. With a long chain omega 3 rich diet, farmed fishes are much healthier for themselves of course, but also for us. For our part, as all terrestrial organisms, only our eyes and brain cells have their membrane constituted from LC-PUFA. Nevertheless, this is important enough to seek to ingest these LC-PUFA in sufficient quantities in order to grow and keep healthy. It thus becomes quite critical to us to preserve farmed fish as a good LC-PUFA omega 3 source!
(Picture: Philip Chou/SeaWeb/Marine Photobank)
I am not alone in coming to this conclusion. Two kinds of attempts are today in progress to take over from non-extensible reduction fisheries and supply more LC-PUFA to aquaculture in the context of its global expansion.
- Aerobic fermentation of an heterotrophic microalgae discovered in muddy marine waters and fed with cane molasses in tanks. AlgaPrime DHA is produced by Corbion for BioMar. Veramatis, a joint venture of DSM and Evonik, produces a similar omega 3 algal oil with corn derived sugar. Compared to forage fish reduction, it is a costlier process reserved for high-end markets. And what about the natural well balanced diet profile with a production based only on one single compound ?
- Genetically modified canola, with an added gene of a microalgae, will start to be planted this year in Australia (Nuseed's Aquaterra) and by 2020 in the USA (Cargill's Latitude). This technology is able to flood the market with its cheap alternative, but without any ethical consideration (try to find any reference to genetic manipulation in their web presentation above), especially in weak and sometimes corrupted developing nations. The natural well balanced diet profile is also missing.
- Insect meal is often presented as a third alternative, but this breeding produces only proteins of interest and saturated oils, not the bottlenecking LC-PUFA.
Anyway, these compounds are only suitable to "modern" agri-food industries which is fond of cracking technologies. Thanks to mechanical (heat, freezing, pressure) or chemical (organic solvent, surfactant, acid or alkali) denaturation processes, each constituent of a natural food is separated in several low-cost nutri-functional compounds, whose sum brings in more money than the original food could have brought. A catalog lists and allows then to combine different components in any wanted food, with the needed biochemical composition, aspect, flavour and palatability. This is the origin of junk-food, "la malbouffe" as we call it in France, ready to eat meals strongly suspected to develop diabetes, cardiovascular failures and hormonal dysfunctions with their related chronic diseases. The same occurs in feed industry's pellet manufacturing. We are not only what we eat, we are also what we feed. Biochemists should use their knowledge to enhance food production in accordance with nature's laws and not against them. This comes from the heart. Let it be said, I believe in organic farming with some biodynamic precepts, permaculture and multi-trophic aquaculture to feed the world, rather than in GMOs and the present industrialisation of animal husbandry.
My ambition is to develop a natural and healthy animal protein source in the high sea desert, far enough to supply some long chain omega 3 rich feed to fish farms around the world (first to family pons and small scale plants). Thus, fish farming would be able to provide a healthy food for us, and forage fish will remain at sea to nourish penguins, seals, dolphins, whales, sharks, seabirds... and wild fish from upper trophic levels we also want to catch and to eat. Rather than just looking down on how fisheries and aquaculture are managed nowadays, I suggest the whole process to be re-thought in a pragmatic way to the benefit of all, as well to fishfarms, as to marine ecosystems and artisanal fisheries. The main thread of my reflection is based upon an implacable logic:
"The better we aquaculture, the less we fish, and let the oceans live"
So HOW are we going to achieve all that ? Let us take a look at all issues we may encounter.
Weather conditions are the first issue encountered when operating any infrastructure on high seas. So let us first choose the only ocean not to be prone to cyclones, typhoons or other hurricanes, South Atlantic. Besides, it is the poorest ocean both in terms of fisheries and maritime traffic, so we should find an unoccupied and safe place there.
(Source: NASA Earth Observatory)
The lack of mineral nutrients for phytoplankton growth is the second issue on high seas in general, and in South Atlantic in particular. Except in some eastern areas, where constant wind from land cause upwelling, algae bloom and related important fish production, it is a real desert out there. Anyhow, we have to content us with the desert areas, because the naturally rich ones along the African coast are already exploited and occupied. Farther west, the nutrients present in the photic zone - above a 100 meters depth where light comes in - are quickly completely consumed by phytoplankton's photosynthetic activity. In these conditions, the phytoplankton cannot multiply enough to feed many zooplankton. That is why the high seas are biological deserts. No existing wind is strong enough here to mix the layers, and the minerals are not massively renewed from the deeper layers, where they stay present in quantity.
(Source: SeaWifs Project)
The challenge now is to bring the existing nutrients from the depth and the light from above together. Doing the math, there are only two possibilities, bring light down or bring nutrients up. Let us have a look at both.
Bring light down:
Due to the aggressiveness of ultraviolet radiation from the sun, and to the constant adaptation of the naturally sinking algae, the optimal wavelength for its photosynthetic activity is within the blue range, the one that have the highest water penetration coefficient. Luckily, thanks to today’s LED technology, we are able to produce just the needed blue light with very few energy. Furthermore LED can easily be deployed in high pressure environments, because, unlike light bulbs, they are not hollow and cannot implode. But, even if we manage to illuminate properly a portion of the dark aphotic zone - below 100 meters depth - with strings of blue LED, we still need to survey, handle and fix a production process in these depths… This is feasible, but too constraining.
Bring nutrients up:
Unfortunately, nutrients are diluted in great amounts of water, far too much to be pumped up with external energy and create an artificial upwelling. It would not be economically viable to spend so much energy. So can we bring up colossal amounts of nutrient-rich deep-sea water without energy? Yes we can :
Antarctic Intermediate Water (AAIW) is a nutrient rich, and low salinity water body, which characteristics are due, among other factors, to the mixture of seawater with mineral rich and fresh meltwater from the southern ice cap. These are the waters, where the Antarctic life explosion takes place every summer. AAIW flows slowly northerly in every oceans. In the South Atlantic, it meets warmer and saltier sub-Antarctic water at the convergence zone, 50°-60°S. There, it sinks to a depth of approximately 1000 meters (3280 feet), gliding over cold, salty and very dense bottom water. A large part of it is flowing northeasterly to the South Atlantic Gyre, where it loses its characteristics by mixing. But a little part of it is flowing due north on Atlantic's west side, until crossing the Vitoria Trindade Chain east of Brazil. AAIW lays at this depth, and does not mix with the upper and under layers, even in this tropical region, where surface water becomes heavier, due to evaporation and induced saltiness increase. The sea stays stratified because the diffusion between the different water masses is too low, no storms are strong enough in this region to mix the layers, and no constant wind from land forms an upwelling.
(Courtesy: Earth' Climate: Past and Future, written by William Ruddiman)
These conditions are ideal to set up a Perpetual Salt Fountain, an "oceanographic curiosity", as first described by Henry Stommel et al. in 1956. If you have a warm and salty water mass above a colder and fresher one, put a vertical pipe between this two layers, pump it up until the pipe is full with the deep water, and then you can stop pumping. The up flow will last perpetually, without any other external energy spending. This is due to the fact that the heat difference between the water masses is conducted through the pipe walls, but the salinity difference remains unchanged. This property has been recently validated on open sea by Shigenao Maruyama et al. from the Institute of Fluid Science, TOHOKU University. In our previous example, we have very salty and warm water above very little salted and colder water. The salinity having the largest influence on density, the salt fountain should be very strong. Here is our solution to bring nutrients up without energy spending.
(Courtesy: Institute of Fluid Science, TOHOKU University)
Furthermore, AAIW, found today at 1000 meters depth in the tropical zone of South West Atlantic, was in contact with the atmosphere about 300 years ago, in other words, long before the Anthropocene, and the wide dissemination of its pollutants. Even with the inevitable transfers between water layers, caused for example by the daily vertical migration of zooplankton, the concentration of anthropogenic pollutants in AAIW should remain insignificant. By considering the present state of seafood contamination with heavy metals and POPs, these waters constitute a very interesting aquafeed production environment. Since several years now years, WHO recommends to eat fish for its healthy omega 3 content, but not more than twice a week, because of its pollutants content. Just before Christmas 2016, a leading French consumer association revealed also, that organic farmed salmon has higher contaminant levels than conventional farmed fish (both luckily well below WHO standards), due to a higher fishmeal inclusion in their feed. On my view, the (still relatively low) contamination of fishmeal is not due directly to wild forage fish, but either to the 30% sourcing of trimmings from higher trophic level fishes, packaged in the filleting factories. In any way, it is time to take serious account of the current contamination of farmed fish with heavy metals and POPs, and to work on it.
Another issue is to build a floating infrastructure with, at least, a 1000 meters deep anchorage, or with dynamic positioning. This is quite preposterous if you consider the scale of the area, and the production we are aiming to. Help is provided here by seamounts, and more specifically guyots with a flat top, extinct volcanoes rising up from the seafloor, sometimes almost to the surface. Such a guyot is perfectly suited to support an infrastructure on its top and pipes along its slopes. In addition, due to Taylor columns effects, seamounts have the particularity to let the isotherms rise a bit, and form a vortex that retains the surrounding waters. This phenomenon allows us to find AAIW at less deep level and, after being raised through the Perpetual Salt Fountain pipes, to keep it a while above the seamount for exploitation.
A last issue is the needed energy supply so far away from the continent. Overlooking fossil fuels which have no more real future, let us have a look on renewable powers.
- Solar power: solar panels, deployed on a large area, are certainly too vulnerable in an open ocean environment.
- Wind power: wind mills have already been anchored off shore, but provide only a non-constant supply.
- Wave power: Wave Energy Converter are fragile mechanical devices and are also unable to provide a regular supply.
- Current power: marine turbines need a very strong current to be efficient and it is better to avoid it in our case .
- Osmotic power: membranes are expensive, cleaning chemicals are needed and the system is very complex to handle.
- Temperature gradient power: Ocean Thermal Energy Conversion plants are also very sophisticated systems and need chemical refrigerants.
What else ? I think on Earth's internal heat power. Yes, geothermal energy on high seas !
Why not, being located just above an extinct volcano, rising up from the seafloor almost to the surface.
And WHERE could this take place ?
I managed to found a suitable guyot in the Vitoria Trindade Chain, east of Brazil, the Davis Bank. It rises from 4000 meters on the sea floor to less than 50 meters depth (160 feet), and has a very large flat top, around 90000 hectares (222000 acres). In the tropical southwest Atlantic, it is the only known suitable seamount, which does not belong (yet) to a national Exclusive Economic Zone (EEZ).
Finally WHAT shall we raise there ?
The core of all production in the sea is phytoplankton, which multiplies rapidly, subject to presence of mineral nutrients and light. From there on, a short trophic relationship with an organism, which has a good conversion efficiency, would be the most effective and healthiest way to produce anything.
Sessile filter feeders like mussels are good candidates, because they belong to the second marine trophic level, don’t spend any energy to swim and cannot escape. The very short trophic relationship between primary production of phytoplankton and production of mussels assimilating it, combined with the very pure AAIW quality, are the unquestionable guarantee of the lowest level of anthropogenic pollutants at the end of the production process.
Mussel aquaculture has been practiced for centuries, even millennia, because it is rather an easy culture. They multiply profusely, attach themselves on any surface or created device, and feed on any organic matter they find. Several techniques are used nowadays. Using long lines is the most productive technique for mussel aquaculture, because it takes advantage of the volume in the water column, instead of a surface. However, this production method, intended for human consumption, is too expensive, and needs to be improved to fit aquafeed production. Several stage sorting and mussel cleaning can for instance be discarded, sparing a lot of time and money. The long lines themselves are too expensive in their actual form, and need also to be re-thought.
(Source: The MARICULT Research Programme)
Despite these observations, long lines mussel farming is by far the world’s most productive breeding method, with currently 150 tons, up to 300 tons, per hectare and per year. To put these figures into perspective, beef production is only around 0,340 ton per hectare per year, almost a thousand times less ! With mussels on long lines, we can reasonably forecast a production between 3 to 6 million tons of mussel flesh (75% is shell) in a square of 90.000 ha, like the flat top of Davis Bank is. This figure can also be compared to the 5,5 million tons of Peruvian anchovies caught in 2018, world’s largest fishery dedicated to the production of fishmeal and fish oil. These were their highest landings since 2011 and won't be surpassed, due to government policy to limit the total allowable catches (TACs). Moreover, 2018 has not experienced the famous El Niño event, periodically resulting in a temporary collapse of this reduction fishery.
However, as a consequence of their relative easiness to be cultured, some aspects of mussels’ biology, like their most efficient diet, have only been poorly documented. We just know that mussels ingest preferably plankton and other organic particles from 5 to 15 microns. Diatoms, the main intake, provide DHA (good for our brain) and flagellates provide EPA (good for our heart), both important LC-PUFA omega 3. The control of mussels’ diet, until now neglected, has all its importance here, especially if it is revealed to be adjustable.
Each mussel filters nearly 100-liter water a day. Retaining all the present particles, its food conversion factor can be very fluctuant, between 30 and 80%. That means mussel produce between 20 and 70% faeces (which pass through the digestive system), or pseudofaeces (which are immediately rejected). These sink and pollute the surroundings, because the organic charge is too important for being degraded by aerobic bacteria during the fall, especially when the bottom is not very deep, what is mostly the case in mussel culture areas. Once the faeces are accumulated on bottom, anaerobic bacteria take place, with its inconveniences. That’s why knowledge about mussels’ most efficient diet has its importance. Especially if we are able to sway this food conversion factor and the nature of the metabolized substances, by using the appropriate phytoplankton mix to feed the mussels. In our case, these particular phytoplankton species can be injected in the rising nutrient-rich AAIW passing through the salt fountain pipes, to let them multiply on their way up, thanks to strings of blue LED inside the pipes. That’s a way to control mussels’ diet, in order to minimize faeces and maximize LC-PUFA omega 3 production.
Now we have the framework. But it will not work as it is, because of the environmental footprint of such a huge mussel farm. To avoid contaminations, it still needs to be atomized between several places, or at least separated in some way, by macroalgae for example. Anyhow, it needs also to be associated with other cultures to become a self-sufficient biotope. This technique is called Integrated Multi Trophic Aquaculture (IMTA) where one species' wastes are recycled as feed for another.
(Source: Fisheries and Oceans Canada, drawn by Joyce Hui)
Mussel faeces cause pollution problems in most of today's monoculture areas. To avoid this, the soluble faeces can be assimilated by kelp or another macroalgae, and the solid ones can be assimilated by scavengers on bottom like sea cucumbers. These will also strongly contribute to the project's viability, because of their value for Asiatic people, who appreciate them a lot as food and medicine. You can read more about it on the website of the IMTA Research Laboratory.
However, despite IMTA technics, such a mussel farm will lead to a huge threat for the existing biodiversity of this rhodolith covered seamount, which counts several species of algae, corals, crustaceans, sponges, fishes, among which some are endemic. In short, Davis Bank is a rich reef biotope as shown in this video below entitled "Fish biodiversity of the Vitoria-Trindade Seamount Chain - Pinheiro et al 2015".
Since this filming in 2005, carbonates mining to provide fertilizers for Brazilian sugar-cane plantations has occurred there between 2009 and 2011, together with mining trials of cobalt-rich crusts. Moreover, since several years now, fishing vessels from China, South Korea, Portugal and Spain are commonly on work there, as we can observe on Global Fishing Watch. If this fleets use bottom trawlers, the reef might be in pretty bad shape.
(Spanish fishing vessel on Davis Bank in April 2018)
(Chinese fishing vessel on Davis Bank in november 2018)
I don't know how this paradise looks like today, but we may perhaps choose a less space requiring marine organism for our purpose. Copepods, especially calanus can also be good candidates. From 13 000 species of known copepods, 10 000 are marine and 5 000 of them are nonparasitic and free living zooplankter, like calanus. These little 1-2 mm crustaceans represent a considerable marine biomass and are naturally a crucial link between energy-producing phytoplankton and fish. Like mussels, they belong to the second marine trophic level. In spring, they aggregate together in huge swarms near the surface, until seawater becomes like syrup and baleen whales can scoop them in big mouthfuls.
(Photo courtesy: Terje van der Meeren, Institute of Marine Research, NO-Bergen)
A single copepod can catch and consume a few hundred thousand phytoplankton cells per day, clearing about a million times their own body volume of water. They feed at the surface at night to avoid visual predators and eventual toxic emanations from phytoplankton. At daytime, they sink several hundred meters down to stay protected. In Polar Regions, they sink until thousand meters depth to hibernate during the cold season and live on their reserves, after fattening up in spring.
This is why their metabolism allows them to build up a very high protein and LC-PUFA content. To be able to sink, they change their oils in more dense fats, wax esters. They accumulate also astaxanthin, a lipid soluble carotenoid, well known for its anti-oxidant properties, which enables them to hibernate with preserved stocks of nutriments. Astaxanthin is also the substance that gives the orange-red color to wild salmon flesh. Fish feed is currently added with synthetic astaxanthin to avoid rancidness and give the right color to farmed salmon flesh.
With a view to calanus breeding for fish feed, some very interesting properties can be highlighted:
- they are already natural fish feed, a whole feed for aquaculture.
- they aggregate together naturally and can thus be easily harvested.
- they have a very high protein and LC-PUFA content, naturally well balanced with all needed micronutriments.
- bound as wax esters, the LC-PUFA are much better assimilated as those of fish oil and lead to very pronounced positive effects on important metabolic parameters.
- thanks to their astaxanthin content, perhaps they don't even need to be processed into meal and oil to be stored at room temperature.
Hope can be given to be able to breed calanus swarms inside the Perpetual Salt Fountain pipes, harvest them on the top outflow and thus avoid threating the environment.
All these conclusions of mine are written without references to all the sources I have used, because I do not claim to have done a scientific work. My project is all the same a solid base to the challenges of fish farming sustainability and oceans’ biological productivity preservation. As a pragmatic ecologist and amateur oceanologist, I think we have to start by installing perpetual salt foutain pipes on Davis Bank.
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