Calverton
Fish Farm
2004
was a very bad year for the Environment Agency's Calverton Fish Farm
in Nottinghamshire - it was the year they discovered Tench Rhabdovirus
anti-bodies in some of their fish - a major dilemma for Calverton
manager Alan Henshaw and his staff, as none of the fish had previously
shown any abnormalities and no dead fish were found.
After gaining specialist advice and much soul-searching, there was
no choice left but to cull all existing stocks, disinfect the site
and start again. Not an easy decision to make, but the EA is accountable
to every angler and angling club in the country, so no risks were
taken and the deed was done.
I visited Calverton in recently to see how things were progressing
with the renewal of the fish stocks and the breeding programs.
Driving through the high cast-iron security gates into the 17.5 acre
site I was greeted by Alan Henshaw the team leader of Calverton, and
over a cup of coffee, Alan told me how the virus had been found in
only one batch of fish, and in only one of the buildings. It was found
by a test recently developed by C.E.F.A.S (The Centre for Environment,
Fisheries & Aquaculture Science), who are a government-body based
in Dorset, and the test had shown just a few traces of the virus,
but that was enough for them to take necessary action.
So with a clean slate, Alan went on to explain the plans for the future
of Calverton and the bio-security procedures developed to minimise
the risk of the disease re-occuring. He introduced me to Neil Lincoln
who kindly guided me around the farm and answered all my many questions
- many thanks to Neil for his patience!
I
discovered I was in the ‘Dirty Side’ of the farm, so I
had to change into some white wellies and wash and disinfect my hands
before being allowed into the farm proper.
The first building I entered (after first disinfecting the white wellies)
was the Atcost building which contained 20 holding tanks for young
fish. At the time of my visit there were 12 tanks of very small grayling,
grown from eggs collected in March. What impressed me the most, apart
from the cleanliness, was the absolute control over the fishes environment.
The water, which comes from the on-site borehole, was temperature
controlled, the oxygen levels and aeration were monitored - in fact
everything was made as near perfect as possible for the fishes well-being.
Anyone who keeps fish for a hobby will know the saying: ‘look
after the water and the fish look after themselves.’
Moving into the ‘Growing on Unit’, after disinfecting
the wellies again, (notice a theme here?) there were 12 tanks, again
with automated quality controls, but in here the amount of daylight
was controlled as well - giving maximum growing potential for the
fish. A purpose-built filter dominated one end of the building, allowing
the water to be re-circulated and to cut down on costs. Again everything
was spotless.
The Hatchery
A short walk to the Hatchery, (the newest of the buildings - being
only 5 years old), the nerve-centre of the fish farm, this is where
all the spawning and egg collection is done.
As you can imagine, bio-security is at a maximum and Neil explained
that visitors are not normally admitted when the farm is in full production.
Brood fish are first blood tested to check for any diseases, the eggs
are collected, fertilised and put into shallow tanks and then the
fish rearing starts in earnest!
Dace can take up to 30 days to incubate, Barbel take around a week
and Tench as little as two days to develop. Each species has its own
individual requirements, it's about now that you start to realise
just how complex the operation is.
Neil Lincoln explains the technical process
of
producing fish - to a slightly over-awed A.T. editor!
Eggs about to be stripped from a 12lb barbel
Artemia
Next
on the list was the Artemia Room - you’ve got to hand it to
the guys, they certainly know what they are doing, they’ve designed
special equipment to grow Artemia (brine shrimp to you and me) but
on a huge commercial scale. They even use de-capsulated or ‘shell-less’
Artemia as they’ve found the young fish can digest it better!
Specially designed vats for growing
shrimp brine - but on a vast scale!
By now I was starting to glaze over... the technical information was
coming out of my ears, the organisation and logistics were phenomenal
and the numbers quoted were astronomical. They can produce around
1,200,000 fish in one year! Just imagine - that’s one million,
two hundred thousand fish - that’s more than enough to stock
a few ponds!
Taking
a breather I walked over to the polytunnels where all the young fish
are grown on - there’s only 22 tunnels - (only!).
Each of the polytunnels has auto feeders and oxygenating units, along
with all the usual monitoring equipment. 25,000 roach were being grown-on
in this particular polytunnel. The humble roach I’m told, is
the most popular species requested from the E.A.
With the the hands of the clock speeding by, it was back to the main
office, (after disinfecting the wellies and washing my hands) for
a chat with Alan Henshaw and his team - and to fire some more questions
at them. They are a patient bunch of guys!
I asked if there were any fish they didn’t breed and I must
admit I was surprised when they reeled off a list comprising of pike,
perch, carp, zander and eels, I thought carp would have been a popular
fish for breeding. Alan went on to explain that it would be a pointless
exercise as there are so many commercial breeders already producing
an excess of carp.
‘Have you attempted to produce any unusual fish?’ I asked,
thinking there might be some catfish or big-mouth bass lurking in
one of the ponds, ‘Well,’ Alan replied, ‘We have
experimented with Shad and Burbot, but of course they couldn’t
be stocked into any of our waters, but we could produce them.’
An interesting thought regarding Burbot, which hasn’t been caught
in our waters since the 60’s, so I had to ask the question -
‘Why not’?
‘Good question! We’re not quite sure why the Burbot died
out, it could be many things: water quality, over-fishing, environmental
changes, predation, disease, but obviously something didn’t
suit them, so we can’t just introduce them back into our waters,
the impact of introducing a ‘new’ species can be catastrophic’
explained Alan.
Not wanting to get into scientific and technical arguments I moved
on and asked about any future plans the team had for Calverton.
‘Getting back to full production’ - was the unanimous
answer, ‘We like to see all our tanks and ponds full of fish
- it’s strange to see them empty’. ‘We might try
and produce some pure bred crucians, there seems to be a place for
them’ Alan added.
‘What’s your major worry regarding angling in general?’
A good question to finish on, I thought. Straight away Alan replied:
‘Fish diseases, with the Koi Herpes Virus a major concern, also
illegal fish imports and perhaps stocking levels at some waters,’
I reckon he’d been asked this question before and was expecting
me to pick-up on the stocking level theme, but being very diplomatic
(and time was running out on me), I decided that perticular discussion
could be saved for another day.
The experts - in front of their delivery vehicle
left to right:
Neil Lincoln, Ian Rockley , Richard Pitman, Alan Henshaw and Ian Cook
Driving back to my office in Chesterfield, I have to admit I was impressed.
The expertise, experience and dedication of these guys is second to
none. Each and everyone of them holding qualifications in fish management
and fish-related subjects.
All the equipment, tanks and ponds were maintained to the highest
standards, in fact it was just how you would expect the country’s
leading fish farm to be - and more. The E.A. should be proud of them.
Until next time - good fishing to you all -
Kevin Miles
