Abandoned Coal Mines Provide Liquid Assets for Fish Farmers

Hatchery International (March/April 2002, Vol. 3, Issue 2)
by: Quentin Dodd

A West Virginia fish-farming operation believes it has found the key to growing chill-loving Arctic char for the New England and US East Coast seafood markets, in the warmth of Appalachia - and it's all in the water from coal mines.

Seed for West Virginia Aqua's (WVA) two-phase program comes in the form of eyed Arctic char eggs from the Canadian east and west coasts, which have been arriving at Charleston Airport in batches of about 100,000 each in recent months - beginning in June of 2001. The eggs are moved rapidly under the watchful eye of program general manager Tina Savage to stacks of incubation trays in a hatchery building at Delbarton. The incubators are supplied with water which is pumped about a quarter of-a-mile (400 m) from an abandoned coal mine belonging to the Mingo Logan Coal Co., which also has an active mine nearby.

Underground conditions at the mine keep the water - which tests well below Environmental Protection Agency standards for solids, iron and sulphur - at a constant temperature of 13.5 - 14.5 °C, close to idyllic for growing char. Above or below that range they don't eat so much nor grow as fast. Temperatures above about 16°C are approaching the upper lethal limit.

After about six to seven weeks the newly hatched fish start to swim up in the trays. They are about one cm long, and look like a tadpole with a very prominent yolk sac. They are immediately transferred to the first of a series of circular tanks, starting with 12 shallower ones measuring six feet (1.8m) diameter, by two feet (60cm) deep. As they grow to four grams or so, they will be divided into smaller lots and transferred into other, deeper tanks about four feet (1.2m) deep. The hatchery has four 15 ft (4.5m) and four 12 ft (3.6m) diameter tanks where the fish will grow to about 25-30 grams, when they will be ready for transfer to West Virginia Aqua's grow-out site at Man. By then they will have spent about 22 weeks in the tanks, kept under high-intensity halogen lights which simulate daylight and are on 24 hours a day.

WVA currently uses a trout diet from Moore Clark in Canada but the feed manufacturer is reportedly designing a special feed for Arctic char. At WVA, the feed is given to the fish by automatic feeders which are on for about two seconds every 10 to 15 minutes, 21 hours a day. The other three hours a day are set aside so that the fish can build up their appetites again.

Savage reports that fish on that regime approximately double in weight every week for the first 10 weeks or so. After that, growth tends to slow slightly but continues at such a rate that the company expects to be selling three to four-pound (1.41-1.8 kg) fish after just 17 months or so. In the wild it would take char at least seven months longer to reach that weight.

According to Savage, the secret is not in the feeding nor in manipulating how much artificial daylight the char receive but in the constant water temperature. Water from the mine is not subject to the temperature fluctuations surface water supplies experience. Growing numbers of fish farmers in both Virginia and West Virginia have taken to using mine water for growing several different species, especially those which like cooler temperatures. West Virginia Aqua selected the site for its growout operation - about 20 miles away at Man - because of the quality of the mine water there, even though a smaller supply requires extensive use of water recirculation.

Typically though, pumped mine water has one drawback, it often has elevated levels of both nitrogen and carbon dioxide, which can be deadly to fish if not stripped out. The fish must have levels below 100% saturation for nitrogen and below 25 ppm CO2 Mine water often runs at 125% saturation of nitrogen and as much as 85 ppm CO2 to bring the two parameters within the safety threshold, NWA treats the incoming water with liquid oxygen. Only small amounts are needed, less than five liters a minute at the hatchery.

West Virginia Aqua, a consortium of three investors who lease the facilities from the Mingo County Redevelopment Authority, boasts of being the first company in the state to install and use a water recirculation facility for its Arctic char grow-out operation, recirculating some 95 per cent of the mine water it receives.

Other similar operations also using mine water are now reportedly following their example and retrofitting, due to the reduced cost and higher efficiency.

"We circulate about 5,000 gallons of water a minute (19,000 11m) at the grow-out site, but only about 400 gallons (1,520 I) of that is fresh make-up water from the mine," said Savage, adding that more companies are realizing that they will not necessarily have guaranteed access to unlimited volumes of water forever.

West Virginia's wealth of mines has clearly proved a boon for the blossoming aquaculture industry, and there is evidently a synergy to the relationship. Mine owners are not permitted, by law, to allow more than a certain amount of water to accumulate in the bottoms of their mines, in case its weight causes a disastrous collapse of the containing hillside. So the owners are happy to get rid of water to the fish hatcheries and grow-out facilities, which in turn appreciate its constant temperature and predictable quality.