From Valerie@stuart.ak.planet.co.nzTue Nov 21 22:30:01 1995 Date: Wed, 22 Nov 95 15:21:32 +1200 From: Valerie Cowperthwaite Reply to: SAED-SHARE-L@cornell.edu To: SAED-SHARE-L@cornell.edu Subject: Re: RFP - aquaculture instructional materials > >I have no special knowledge of aquaculture, but I confess I am > >suspicious about it as a form of "sustainable agriculture." First, > >are we talking marine or freshwater aquaculture? If marine, then > >how can an intensive managed production system (aquaculture) begin to > >equal the immense natural productivity of the oceans, which captures > >solar energy on every square foot. When I asked someone about > >marine aquaculture feedstock, I was told they are fed rough fish and > >fish waste from deep-sea fishing, plus grain produced on the land. > >I didn't get an estimate of the ratio. The point is, shrimp or salmon > >or whatever are most certainly NOT subsisting on the solar input > >associated with the surface area of their confinement space. So it sounds > >like maybe the growth of marine aquaculture depends in part on > >the continuing mining of the wild marine resources AS WELL AS industrial > >agriculture. Please, TELL ME IT ISN'T SO! > > > >Okay, so how about freshwater aquaculture. In a farm pond, integrated > >with a whole-farm production system, aquaculture sounds good. Inputs > >include residues and wastes as well as maybe some human-edible products > >from the farm. > > > >But I am guessing that intensive catfish, trout, tilapia, etc. are going > >to be mostly fed from grain, produced in industrial farming systems. > >Again, please TELL ME IT ISN'T SO. > > > >I'm not claiming to be informed, I'm just trying to be a skeptical consumer > >of ideas. What really sets me off is that this RFP talks about > >"aquaculture AS sustainable agriculture," not "aquaculture IN sustainable > >agriculture." > > > >I hope this comment will lead someone to share insights into these > >concerns I have with aquaculture. > > > > A farm I am associated with has incorporated a saltwater fish farm into its sustainable practices. The saltwater ponds were engineered out of mudflats in front of the mangroves, working with natural contours, tidal flows, etc. One man did this with one digger, the farm covers 5 acres. A system of valves works with natural tidal flows and a channel running partway round the entire farm feeds the individual ponds which are all graded to allow different depths for different sizes of fish and for draining when necessary. The main species farmed is the grey mullet which were bred from spawn caught from the breeding ground in the mangrove - only a small percentage at any one time were taken - one man and a large 'butterfly' net was all that was involved. The initial foodstuff was meatmeal which is a natural byproduct of the farms meat stock. This was used to feed the algae which is the natural food of this species of fish. As the algae became established meatmeal was discontinued. At different times other feedstuffs were used according to what needed to be recycled and fitted into the nutrition needs of the fish farm. For instance feather meal was used at one stage, milk powder at another. Nothing is being put in at this stage. Over time other associated water species have found their way into the ponds and live harmoniously in this ecosystem. Nets cover the ponds to protect against bird predators, and plants natural to the site have been re-established. Tests showed the water at the outlet into the harbour to be purer than that actually in the harbour - the Kaipara Harbour is the second largest natural harbour in the world and certainly one of the cleanest. When fish populations begin to increase too fast stock is returned to the harbour through the outlet system. I am not a technically minded person and some of this detail may be a little inaccurate but the concepts are pretty much what it is all about. The over-riding motivation in setting this up was to show that quality protein could be grown sustainably in harmony with the existing eco-system and in fact could assist it, which it does through water purity, providing breeding areas and restocking the harbour. The model has aroused interest in local Maori groups whose traditional protein staple was fish. It has also been studied by students wishing to help solve problems in third world and developing nations where our traditional beef/sheep etc are not appropriate suppliers of protein. I should add that the fish farm is part of a 1,000+ acre farm running beef and dairy cattle, plus sheep, tree crops, timber etc and a number of other 'diversified' operations. It is a commercial scale operation and proves I think that choosing the sustainable species (pl) for your locale, relating that to what 'wastes' are available locally in terms of inputs needed means that aqualculture, even 'intensive' saltwater aqualculture is a possibility. I believe there are also models in permaculture concepts which involve a tiered system of raising small livestock, e.g. poultry, with fishponds beneath which are 'fed' by the waste from above. While this obviously lends itself to small scale operations it could surely be adapted to commercial scale salmon etc farming.