The problems of feeding a growing population seem insurmountable, on the surface. Sustainable seafood supplies is one such example. We’ve posted elsewhere in this section of our site the conundrum of making sure everyone has access to the essential fatty acids present in sea food, without depleting the word’s fish supplies. Professor Michael Crawford has added his own response to the thread, on the theme of marine agriculture:
“A quantum leap is required, but it is not a difficult one. Japan has made a start, and China is the world-leader in freshwater fisheries, as well as having had kelp in production for thousands of years. And freshwater fish farming is definitely a way forward. The rivers and lakes used to contain abundant trout and the like. However, the extent of freshwater is limited; whereas the oceans account for 71% of the planet’s surface.
Over-fishing is idiotic. Pollution of lakes, rivers and coasts is unpardonable. It needs to stop. The problem is, we are using the oceans with a Neanderthal mentality of hunting and gathering. Our pollution makes it worse. In my lifetime, the Firth of Forth, a once great fishing and seafood resource, has gone – poisoned by Edinburgh and industry. Aquaculture, which means feeding fish to fish, has now reached the point of having to use land-based vegetable oils, and even chicken meat.1
The solution as I see it is marine agriculture, such as they are developing in Japan. This means growing sea grass pastures on the sea bed for fish, just as we grow grass pastures for sheep and cattle on land. They have developed artificial reefs designed to merge with the behaviour and feeding grounds of specific species. Kelp forests can be grown, too.
This is essentially farming in the sea. It is sustainable, as it does not rely on feed input. Sunlight and the mineral wealth of the sea does it. As with land-based agriculture, you can develop sea plants to optimise productivity. Planting sea pastures also provides a safe zone for tiny juvenile fish, so enhancing survival rates.
Moreover there is a triple benefit. Firstly, the byproduct of fertiliser for land crops. Secondly, health: the brain evolved in the sea 500 million years ago using the omega-3 DHA for its signalling structures and function. It sill uses and needs the same. The rise in mental ill-health is a consequence of focusing the food system on protein and calories – good for body growth, but lacking in brain-specific nutrients. The brain is made mainly of fat requiring highly specialised essential fatty acids. The marine omega 3 are also good for heart and immune system health. Thirdly, there is the benefit of a counter to global warming – shellfish trap and sequester CO2 in a big way. Restoration of the great oyster beds worldwide after cleaning the estuaries would be like planting rain forests.
1 The lack of fish to feed the salmon in aquaculture is a huge problem. Over two-thirds of the total global salmon aquafeed production is produced by two companies: Skretting (Nutreco) and Ewos (Cermaq). The top three items in the printed ingredients list of Skretting’s salmon feed are poultry meal, fish meal, and poultry fat. Feathers are included too. One has to assume that poultry means intensively reared chickens (which in the UK still account for 95% of the poultry eaten). Chicken fat is totally different to marine oil, being largely omega-6 linoleic acid, which competes with the omega 3 of marine products.