As Paul Greenberg points out in his book Four Fish, when salmon aquaculture was launched in the 60’s and 70’s the idea of polyculture was lost, farmers were more attuned to the prospect of bringing high value species to market. Feedlot-style monocultures arose in pristine salmon country along temperate coasts of the world and attention was not always paid to farm site selection, effects of effluent, fish toxins, fish quality and spread of disease. In some places, effluent release was unchecked and the bottoms of bays and tanks were cloaked with the ooze of refuse.
The practice of feeding fish fish meal caused the bioaccumulation of PCB’s to unacceptably high levels, a problem that has plagued the farmed-fish industry since its inception. For each one pound of farm-raised salmon, three pounds of fish meal must be consumed, which not only accumulates these residual toxins but is an entirely unsustainable practice, wasting fish to grow fish.
Recurring infections and environmentalist opposition led the industry to reconsider this practice. In the 1990’s and early 2000’s there came pioneers like seaweed expert Dr Chopin from France who moved to the Atlantic Canada region and applied new farming concepts that lead to fish polycultures, improving the sustainability of the practice. By including algae, seaweeds, artemia, microorganisms, urchins, mussels and sea cucumbers, waste was removed, infections remedied and salmon quality improved as did levels of Omega 3 fats, DHA and EPA. New markets opened up supporting cosmetic, health and food industries.
In Peru years ago, I visited a town called Paracas, which means sand desert. The village was barren of plant growth for there had been no measurable precipitation in recorded times. A boat trip to a nearby rock formation though revealed an abundance of life where the ocean met the cropping of stones. Bats, pelicans, ducks and gulls deposited their waste on the rocks so much so that the stones were plastered in bleached white guano. On the shore were hundreds of seals barking their pleasure for the abundance of sea life that evidently was endemic to that particular spot. Our guide pointed out that the bird guano created fertility for the area and that the waste nourished the sea which provided mussels and clams for the seals, sea vegetables and fish fry for the larger fish and ultimately an entire ecosystem of nourishment recycling from the droppings of birds. This polyculture serves as an example of that which constitutes a self sustaining environment. The true integrity of poly culture exists beyond the most obvious and in fact includes insects, semi aquatic larvae, bees, lizards and even four legged animals. A diversity of animals and organisms balance the ecosystem and when allowed to play their role, create an abundance that extends beyond the feedlot mentality of raising one food group exclusive of the many others.
The future of fish farming will recognize the importance of these relationships. Our perspective must shift not simply towards what is organic, but instead focus on what is truly sustainable in the broadest sense of the word. For instance is it necessary to feed fishmeal to fish? Not if we hope to avoid cannibalization of our limited supply or toxic PCB buildup and harm to our health. What fish is perceived as popular today may not be practical tomorrow. Is the fish we eat rich in Omega 3 fish oils? Does it thrive in conditions that are suitable for farming? Are the farming biproducts recycled on-site to forms that are integral to the health and performance of the farm without need for treatments or nutriments derived off-site?
As with land based permaculture techniques addressing similar terrestrial farming issues, bioponics paves the path towards a culture of food production that includes water based animals and organisms. The success of which will require a more holistic consideration of factors including the reduction of labor costs, energy use, the conservation of water, the integration of waste plus and the preservation of diversity.