Breakthrough technological innovations against the diabetes epidemic2019/04/15
Seafood: making resources truly sustainable
There is still plenty of room to exploit the wealth of seafood products. However, just like on dry land, the question is how to ensure that seafood remains sustainable: with the means available to us today, the world’s oceans are no longer immune from waste and pollution. A number of avenues are now being explored to remedy this.
“The sea is everything! It covers seven tenths of the terrestrial globe. Its breath is pure and healthy. It is an immense desert, where man is never lonely, for he feels life stirring on all sides. The sea is only the embodiment of a supernatural and wonderful existence. […] The ocean is the vast reservoir of Nature.”*
Written almost 150 years ago, these words, which Jules Verne puts in the mouth of Captain Nemo after the memorable meal – memorable because it consists purely of seafood – he shares with Professor Aronnax, still resound with the same intensity even today. As we become increasingly aware of just how finite our world is, there is a clear temptation, in our desire to exploit the planet’s resources, to seek some respite in the oceans. However, while there is undoubtedly still plenty of room to exploit the oceans’ wealth, things are not so simple when it comes to ensuring that seafood remains sustainable: what are the opportunities and obstacles as regards virtuous environmental management of marine resources?
Although the oceans might look like a huge space to explore, marine resources are not inexhaustible
As quickly as we are discovering the huge range of applications for products of the sea, we are also becoming aware that, while the oceans might look like a huge space to explore, marine resources are not inexhaustible either… Worse still, we have been very slow to realise that, thanks to the water cycle, the world’s oceans are becoming the final resting place for huge quantities of non-degradable waste, creating what some are calling a “seventh continent” made up of myriad particles of plastics drifting in the middle of the Northern Pacific and now covering an area six or seven times the size of France! This waste is now found in marine organisms, which also harbour – in high concentrations within the trophic chain** – synthetic chemicals, notably resulting from medicines and pesticides, more or less severely and permanently disrupting species’ reproductive cycles and genetic integrity, and even their very existence.
However, it is not enough to clear the seas of these pollutants to protect the health of their inhabitants: it is just as urgent to prevent overexploitation of marine resources, primarily by ensuring they are only removed at a rate that allows populations to remain stable. Furthermore, shortages of certain species have prompted humans to look further and deeper for new ones to catch. However, as has happened with the grenadier, which flooded fish markets in the 1980s as an alternative to hake, we are already seeing populations decline, forcing authorities to set ever lower fishing quotas… Fisheries are now having to be controlled by satellite monitoring of authorised vessels; alas, this does not prevent poaching, which often takes place in international waters, making it all the more difficult to curb.
Around 600 species and groups of species are farmed
As on dry land, the answer seems obvious: it is time to stop simply catching fish and other seafood; we must now cultivate them! While some species – notably freshwater fish like carp – have been farmed for millennia, only recently have quantum leaps been made in farming and thus producing more and more marine species: around 600 aquatic species and groups of species are now farmed, including over two thirds of fish species, as well as around a hundred types of mollusc, 60 or so species of shellfish, almost 50 varieties of seaweed, and so on. Mainly thanks to carp, China has the lion’s share of this production, accounting for over 60% by weight, while Africa’s share is still modest, growing from 0.5% to 2.5% of the global contribution in the space of 20 years. All projections show that in less than two years, total tonnage arising from farming will exceed volumes from fishing. This is already true if you include products intended for non-food use.
This growth in aquaculture production is coupled with an explosion in the seafood trade, so patently obvious is it that areas conducive to fishing and the development of large-scale aquaculture no longer coincide with areas of human habitation. Thirty-five percent of halieutic*** resources are involved in international transactions (including non-food uses); by contrast, only 10% of meat is shipped beyond its region of production.
The vast majority of species promoted by fish farming are carnivorous
Despite its apparent virtues, the development of aquaculture poses two problems: pollution resulting from areas of ever more intensive farming; and the fact that, unlike in virtually all types of land-based breeding, the vast majority of species promoted by fish farming are carnivorous. In other words, to produce fish for use as human food, you have to catch the species needed to feed them, known as forage fish. The second-largest tonnage of fish, behind the Alaska pollock (3.4 million tonnes in 2016) and ahead of tuna, is still the Peruvian anchoveta (3.2 million tonnes), a major base ingredient in fishmeal and fish oils produced for use in aquaculture.
This growing awareness of the two dead ends to which traditional practices lead is guiding current research on aquaculture.
As regards the risk of pollution and eutrophication of dedicated spaces, the main field of research goes by the name of multi-trophic aquaculture, a technique that consists of linking two or more species by encouraging commensalism**** between them. Nutritional residue falls to the seabed, where it is consumed by scavengers such as echinoderms (e.g. sea urchins and sea cucumbers), while fish and shellfish faeces also benefit other species: for example, some seaweeds are able to recycle nitrogen and phosphate nutrients. It should, however, be emphasised that these efforts are still in their early stages: it is very difficult to replicate and, above all, sustainably control anything approximating an ecosystem, especially in an open environment.
Efforts to limit the use of forage fish
The other focus of research obviously consists of attempting to limit the use of forage fish. There are two possible approaches, the first of which is to give preference to herbivorous species. Unfortunately, these are few in number and their flesh is often less flavourful. Of the species most commonly found at fish markets, efforts are currently being made to farm mullet (or grey mullet). Tilapia and, to a lesser extent, panga also meet this requirement. The second approach is to reduce as far as possible the amount of animal flesh used in aquaculture feeds. However, it is vital to ensure that such feeds continue to provide sufficient energy and vitamins, and that they remain appetising for farmed fish. One interesting approach is to incorporate insect-based flour, only recently authorised for use in fish food – a practice that is no doubt set to rapidly expand.
Marine species are no longer simply there for the catching; rather, they must be cultivated in other ways, applying what we’ve learnt on dry land by favouring relationships between living species for maximum mutual benefit and sustainability: this is a major challenge, and one that a farmers’ bank like Crédit Agricole is logically particularly well placed to help meet.
Benoît Bousquet - benoît.firstname.lastname@example.org
* Jules Verne, Twenty Thousand Leagues Under the Sea, 1870
** A network linking organisms living in the same biosphere, through flows of energy and biomass that pass between them, particularly as a result of organisms feeding off each other.
*** Of or relating to fishing.
**** A relationship between two organisms in which one provides the other with food (sometimes on a reciprocal basis).