“Memoirs” of a Clam Farmer
Born in Belgium in 1940 during the turbulent era of WWII, Phil Dor
began his life on the run. After settling in Holland, he began his
education in Holland and finished it in Belgium. Phil’s
pioneering spirit inspired him to start his first business venture
in a game birds farm (pheasants, etc. for hunting). In the late
sixties, his adventurous personality led him to New Caledonia
where Phil owned and operated a pet store and his for exposure to
marine tanks and coral reefs. But the travel bug bit again, and
after some bush-walking in remote Indonesian islands, Phil met his
wife in Singapore and began the first commercial edible mussel farm
there. Imported Californian Pacific oyster was soon added to
However, Phil soon found out that doing business in Singapore as a foreigner at that time was difficult, so he moved his mussel farm operation to Brunei, beginning with an impressive mass translocation of the mussel spat via air. The initial success in Brunei was great. However, Phil soon found out that people could pick off mussels from just about everywhere without having to pay for them. So once again, he (now with a family) set off to another location: Cairns (Great Barrier Reef) – where he was offered a job to manage a reef aquaculture facility (Reefarm). After 12 years in the tropical, blistering heat of Cairns, Phil and his family moved to Perth in 2000, where he is starting from scratch again for the last time. His current projects lay in coral farming through spawning (not budding), and the launch of his latest invention for the benefit of all aquarium hobbyists: EzyReef.
It all happened on Fitzroy island near Cairns (Australia) from 88 to 91. Reefarm was the first commercial giant clam farm in the world and at that time only 2 research projects existed, one in Palau (J. Heslinga) and the other on Orpheus island by J. Cook Uni (J. Lucas, R. Braley & J. Barker).
I was appointed hatchery manager in Feb 88 (at the end of that year’s breeding season) after arriving from Singapore where I had managed edible oysters and mussels farms.
Reefarm hardware was quite impressive: 4 deep raceways 20 yards long, 6’ wide and 4’ deep and one shallow raceway same length, 16’ wide and 1 ½’ deep, plus a 30,000 gal seawater storage tank that was filled 3 times a day.
Farming techniques before my arrival were based on similar extensive methods used in Palau and results were extremely unreliable and poor. Only J. Cook was using intensive techniques and their results still could not pass the 100.000 units because of the very difficult methods used.
The low-tech method was spawning in very large raceways, feeding larvae with algal cultures for about 10 days, and then hoping for the best until juveniles were visible to the naked eye 4-5 months later, My boss (a Cairns dentist) called it the “mystery phase”.
My initial reaction was that this method was totally unacceptable for a commercial operation as too unreliable and inefficient. Besides that, the species farmed so far T. Gigas and T. Derasa had only a very limited market in Taiwan, when T. Crocea showed almost unlimited market potential on the Japanese seafood market.
First I started to divide each raceway into 3 compartments to increase the number of possible spawning experiments and then I started collecting local Crocea brood stock and my first (spontaneous) spawning was from 6 Croceas in Oct 88.
Croceas can have between 20 and 30 million eggs each, so I started feeding the larvae at day 2 till day 11 and at day 12 most larvae had settled and bottom samples revealed “millions” of crawling tiny (about 120 micron) juveniles. Super result I taught!!!
After settling and a 95% water change I started running unfiltered seawater into the raceway at a rate of 3 times total volume per day, and everything seemed fine.
Less than a week later green filamentous algae appeared and was growing about 1000 time faster than the juvenile clams, and only 2 weeks after settling the now 1” hairy algae was starting to suffocate the juveniles still only about 150 microns.
At that rate everything would be lost within days, no “mystery” about that, so I took an impulsive and drastic (but logic) measure and scooped up everything from the bottom with a plastic dustpan and put the whole hairy mess through a mosquito mesh under water sieve.
Not surprisingly the hairy algae was very easily separated from the tiny juveniles which were thrown back into the raceway, and again bottom sampling revealed insignificant mortality, so this operation was repeated every 2 weeks for about 3 months.
Later Sea hares (slugs) had appeared and taken over the removing of the hairy algae. At 5 months the result of this new “experimental” method was a carpet of 1.6 million juvenile Croceas 4 - 5mm in size, and my boss was already making big plans for next year.
Unfortunately, soon after some regular daily mortality started, J. Cook Uni was called in but could not help, and mortality kept going severely for another 2 months till I finally convinced my boss to install an aeration system and to run it during the night as well and the problem was solved.
The final result was 1.4 million lost juveniles from one spawning alone. But luckily other spawnings had filled the other raceways in the meantime.
The next breeding season my boss became greedy and wanted us to experiment also on fish, prawns post larvae and pearl oysters, and all that without increasing the hardware or even putting the yearlings at sea, and to top it all, by putting us on part-time shifts.
I did not want to play “Superman” and resigned early Dec middle of breeding season, and about 2 weeks later the hatchery was almost totally devastated by a category 4 Typhoon called “Joy” on Christmas day 1990.
Only the yearlings in the shallow raceway survived and these were sold on the German aquarium market two and three years later. J. Barker from the J. Cook project took over my position but never managed to produce much as he switched over to intensive methods, and Reefarm was finally sold in 1997 for prawn P. L. production.
During my brief stay at Reefarm I did not passed on my “innovative” and very successful farming technique to anyone else but once to J Barker, but he judged it too “crude” and never used it again, and if the prices of clams on the U.S. market are any indication nobody else did.
These prices are quite amazing as we had calculated that for the huge 500 million clams/year potential Japanese seafood market we could (with the right investment and location) have produced Croceas at 25 cents each/year!
After my last aquaculture job I became aquarium lease & maintenance provider, did some limited coral collecting and later coral farming but gave this up when it became obvious I could not get an export permit (bureaucrats) and the local market is not viable because still relying on natural collecting.
Now retired, I’m trying to launch a new aquarium system I patented combining my aquaculture and aquarium experiences for super reliability and efficiency with minimum complexity: www.ezyclean-aquariums.com
Husbandry and farming tips:
Before aeration was installed we were also loosing the adult clams used as zooxanthella donors after day 12 of each larval cycle (mass larval mortality period), and this confirms my belief that adult clams are extremely sensitive to lower oxygen levels, this would explain sudden and unexpected death of healthy looking clams. In tanks they should get well circulated water directly targeted at them.
Other problems encountered with wild stock was pyramedellid (2-3mm white) snails hiding near the byssus or in the clam’s flutes, these can kill adults clams and affected clams show signs of disease by not opening fully during day-time.
Wild collected Crocea brood stock could not be used subsequent years because of parasitic gonad infection after spawning, and clams with damaged byssus (not attached to rock any more) were needing special protection from predators (worms, fish etc). Farmed Croceas had great difficulty reattaching once they reached 3cm (about 1,5 year)
The lesson for hobbyists is never to buy clams not attached to rocks, these are most probably wild collected and not really farmed, as serious farms should sell Croceas at least half incrusted into rock, Maximas and Squamosas well attached onto rocks.
Farming in itself is easy if you know what to do: first the brood stock must be over 10 years old (10 – 15cm), then properly conditioned over a period of 6 months in very stable and very gradually increasing temperatures. (this is the most difficult part if not at sea)
Once biopsy confirms the clams are “ripe”, a 2 –3 temp shock combined with small salinity shock will trigger the spawning. Use only 2 –3 clams per spawning, place them in a black coloured plastic 10-15gal bin.
The sperm always comes first and looks like smoke, let them give 2-3 puffs only then remove to second bin until they start blowing eggs (look like fine granular sugar) use magnifying glass, then put back in first bin with other egg blowing stock. No need to add sperm water to avoid polyspermy.
After about 20-30 min of egg blowing pour content of bin into 1000 gal well aerated tub, start feeding larvae at day 3 up to day 10 with algal cultures high in omega 6.At day 9 spread a very fine layer of fine sand into your tub. When most larvae have settled (day 12) do a 95% water change and hang 2-3 adult clams for zooxanthella transfer.
In closed conditions you would need a good filter system to keep water clear, and good lighting system, and juveniles should be “fed” with fertiliser once a week. After that just watch the filamentous algae and sieve them out every two weeks.
At 5 months Croceas and Maximas should be 4 – 6mm in length, at one year the biggest will be about 2,5cm and the smallest about 1cm. At this time they should be placed individually in/on their own rock, and fil-algae control should be done with turbo snails.
Statistics: 5% are super fast growers, 10% fast growers, 70% average growers, 10% slow growers and 5% super slow growers. In Croceas 98% are normal blue, and only 2% are special colours, unless selective breeding?
For any hobbyist which would be dreaming about producing clams in his small set-up, unfortunately this is not possible, not because of the difficulty which is not really much, but more because of the infrastructure and amount of water involved.
But clams are certainly not the “sacred cows” close to extinction some make you believe they are, here in Australia all species are still quite common over the full length of the Barrier Reef (or about 1000 miles) and on Orpheus island’s fringing reef Croceas are so plentiful that you can not put your foot down without standing on one or two.
The high prices asked for clams can be justified by the rarity of the special colours in demand (only about 2% of production), but the interesting question is what is happening to the other 98% common coloured clams???
Also, many clams are still sold without being attached to any substrate and this shows a complete lack of understanding by the farm and/or dealer, because these clams are doomed for sure if they are Croceas, Maximas or Squamosas. Only Hipopus, Gigas and Derasa loose their attachment and can live long without it.(50 to over 100 years).
Clams are ordinary bivalves, generally very hardy and very long living as long as they have the right conditions, and it’s up to the hobbyists to make sure his clams are getting what they need: clean water and shelter, protection from predators and food.
I’m sure all hobbyists do their best for their clams, but the husbandry of clams in aquariums still seems to have a long way to go before losses can be reduced to a bare minimum.
I did 3 years of clam farming but after that ironically I never kept a clam in my tanks as it is not allowed in Queensland, so with clams in aquariums I guess I still have a lot to learn, and for that I’m very glad I discovered #reefs a few weeks ago. Let’s talk! Phil Dor.
Phil's pictures can be viewed here.
Questions & Answers
Who was farming the clams at JCU?
In charge was Rick Braley.
What is the most "hardy" clam for a beginner?
How does an aquarist get rid of pyramedellid snails if they find them on their clams?
Brush them off and check a week later.
My question is on this new disease I had seen posted, which attacks and kills an entire tank of clams in a matter of days, is there any treatment? And how bad has this hurt the clam farming?
That forum is still going on.
What phytoplankton species to you prefer to feed to newly settled larvae?
The ones high in Omega 6. Cultures look brown at full strength, not green. Sorry, I forgot the names.
Is crocea are the most valuable food product and so easy to grow, why does everyone grow maxima, squamosa and derasa? I know Orpheus used to grow gigas as well (I was at Orpheus only a few days ago) and also went to Aquasearch on Magnetic Island, no crocea at all.
Because the market in Japan wants "millions" and it will take "millions" of dollars to do that.
What is your favorite clam?
Can you give some advice on water flow precautions. I always hear that high currents will make some clams close, but yet I see amazing clams in aquariums that have high current. Is there any truth to the flow restrictions?
I have no experience with clams in tanks. But I would favour good current conditions.
What should I do if my clam starts to gape?
If possible, get them out of there and in brand new sea water.
How do you explain the success of so many aquarists who purchase clams without a substrate attached?
I wouldn't do it.
Do I need to feed my adult clam anything?
No, they are not filter feeders.
What lighting does my clam need?
Metal halide 10,000k.
I have a maxima which has brown blotches. started when it was about 1.5" (2 yrs ago) in size I've seen this on many clams...any idea what causes it?
No idea. Is it on the mantle or in the mantle?
Might be genetic mutation
Rick Braley still does Aquasearch on Magnetic Island right?
I don't know.
Could you explain what the requirements would be for a small clam farm for someone who wants to lease oceanfront property using NSW.
First a good diesel pump to pump about 100 000 liters at a time. Then 5 or 6 circular tanks for the spawning and rearing of larvae.
Do you have any plans on the making of a book? Or possibly other books in the making related to clam farming?
No plans But if you want more info please contact me at here.
What exactly is polyspermy?
When more than one sperm reach one egg at the same time, never works.
What do you mean exactly by "hang 2 to 3 adult clams for zooxanthella transfer"?
Hang them in a basket in the race way or tank
What is the success ratio of saleable clams versus spawned eggs?
1 to 2 percent could be increased with right equipment.
Last question, how many clams can a man eat before he gets sick? ;-)
Not many :) I got sick at the first one.
Thanks for the great Talk, Phil
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Last modified 2005-02-07 05:53