This is an account of what went wrong the other week, I truly hope this never happens again, but your help is needed to ensure that.
Swimming pools for fish farming?
We use second hand swimming pools for the fish and on the whole they work really well. They are a super cheap option, and having no money, being able to pick one up for as little as £50 is a real bonus.
We have a duty to keep our fish in the best way possible and a 15 foot swimming pool allows for a large volume of water to be held for the fish. Wherever possible we try to use second-hand equipment so we can keep our impact on this beautiful planet of ours to an absolute minimum, and for a long while these have worked, and for many of the fish, we keep they still do work.
The great thing about swimming pools is that they are round, allowing the fish to swim without stopping, rivers don't have corners, so fish find them hard to cope with. Creating a natural swimming pattern is important for fish welfare. Secondly, they hold a large volume of water for very little cost. Our 15 foot pools hold around 3000 gallons. This allows us to hold a lot of fish by the time you add on another 2000 gallons held in the filtration system, plant trays and sump. And there are many 2nd hand pools available each year, I am always shocked at how many people purchase a new one every couple of years.
Now the down side. They don't cope with big fish.
Our sturgeon are growing fast which is amazing, quicker than we thought they would according to growth data we have been able to access. But that means they are close to outgrowing the ponds but also if they decide that they're going to splash about ( which they do quite often) they can do things like one of them did.
On the Monday I got a call from Dave in the middle of the afternoon when he got to the greenhouse to say get to get there quickly. The sturgeon were belly up, and the pond had split.
Those are words that fill me with dread, because belly up usually means dead and sturgeon are at the heart of everything we do.
As we only have one car at the moment I got our neighbour to drive us to the greenhouse. Myself, James, Robbie and Lucy, Robbie's girlfriend, all jumped in her car. James was able to grab towels and clothes for Dave, sadly not for anyone else though, and we headed up there as quickly as we could.
When we got there David was a little bit calmer as there were only a few of the fish that he hadn't been able to bring around already. The pond was still holding enough water for the fish to cope with and he was topping it up at roughly the same rate it was leaking. He had been able to pump pure oxygen from our oxygen cylinder into the water which had brought most of the sturgeon round straight away, they are very oxygen sensitive. This was necessary because as the water had dropped from the hole that had appeared in the pool the oxygen levels had dropped to a level that the sturgeon could not cope with. It is the one thing that affects them, sturgeon are really tough strong fish but if the oxygen level drops you have roughly two hours to rectify everything to save them, thankfully he had arrived in time. Although the water was still slowly slowly dropping it was a slow enough leak that we could buy ourselves time by adding fresh water. With the added pure oxygen, extra water pumps moving the water around to increase oxygen levels and extra air pumps in the pond plus increased water level most of the fish had come around on their own very quickly, and were out of danger.
That just left 10 that we were very worried about.
The trick to helping sturgeon recover from oxygen depletion is to hold them directly over fast flowing water which is rich in oxygen. Holding them like this so the water is going through their gills is a little bit like putting an oxygen mask on a person.
David had been standing in the pond tending to those that were affected directly over water sources, but we needed him to start taking other action to work out where we were going to put the fish because the pond obviously needed fixing urgently. So Robbie and I jumped in the pond and took over fish holding duties. The water was very cold. We try to keep it as cool as possible for the sturgeon as that keeps the oxygen levels high and more like the natural temperatures they would live in. Whilst we worked with the fish Dave got a second pond ready for the smaller sturgeon and then started moving the largest sturgeon into the other 15-foot pool.
All in all Robbie and I stood in that pond for four hours trying to nurse those fish back to life.
Robbie in the pool.
We saved two of the ten who were struggling and of the 60 sturgeon we could have lost this was not as bad as it could have been, although every fish lost is damaging to our work and of course the fish. Every single sturgeon is so precious and hurts us if we lose any of them.
They are not just fish to us they are our life's work for and as most of the species are on the critically endangered list or endangered in the wild every fish is really important. There are very large scale farms across the world who keep hybrids or only keep one or two species we have always prided ourselves in trying to have a diverse collection of sturgeon not just because we wish to produce caviar at some point but because we believe in being able to breed these sturgeon to keep the populations diverse around the world.
It turned out once Dave headed back to the greenhouse the next day and the water was all out of the pond, that one of the sturgeon had poked his nose through the side of the pond. It must if been spooked by something, sometimes there's a loud noise outside or something that would disturb them and they swim really fast and bash against the side of the pond. As you can see from the picture there is a nose shaped hole in the side of the pond. One of the things that really helped stop the pond completely splitting and all of the water coming really fast is that we double skin the swimming pools having had one that a few years ago did completely split! We now never take that chance and always have two liners sitting around each other. This means that only one is ever going to split at any one time and it gives us plenty of time as in this instance to save the fish.
Pressure washing to find the hole - The hole! - Always a shame to remove he life on the sides of the pond that help make it a living system.
As we believe passionately that nothing should go to waste we have skinned the surgeon that we have lost and the skins will be tanned to create leather when we have a bit more time. The bodies we have composted, and have already completely broken down in our hot composting bays. It did give us a really good opportunity to check whether we had worked out the sexes of the fish right. Of the eight two were too young to tell, two we got completely wrong and the other four we had got right. Sadly one of the females had a belly full of eggs which weren't quite mature enough to actually be caviar. We believe this is why she didn't survive because of her extra body mass from the eggs, she struggled with the lower oxygen levels quicker and sooner and for longer than some of the others.
Dave’s patched the pond, a career of 35 years in pond maintenance and building means he is very good at repairing ponds so they are safe. And it's almost at the time of writing it's almost ready to have the fish put back in but really need to stop using swimming pools especially for the sturgeon.
We've been drawing up the plans for the system at our new site at Boldre and we have spaced it all out so that there is room for 20 ft metal sided ponds lined with butyl pond liner. This is the most secure way to keep these fish. The ponds will be round and they work beautifully in fact they are used around the world for fish farming.
Downside is that they are around £3000 each and we don't have a penny to rub together! Everything we do is on a shoestring but now I really do need some help to actually achieve keeping our beautiful amazing fish safe.
If you would like to help us there is a donation link at the bottom of this article you can also find it on our home page with more details. Even if the moment we can only get one pond to house the biggest surgeon we would be intensely grateful and it's the key to us progressing with our regenerative aquaponics farm. It is time for us to prove everything we've been saying over the last few years, that aquaponics does work on a community level and can provide a planet friendly addition to farming in the UK.
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