A new fish habitat is being created in Halifax Harbour, thanks to a $25-billion shipbuilding contract won by Irving Shipbuilding.

A reef ball project got underway Tuesday morning as a result of a $200,000 contribution from the company – a tradeoff for work being done to expand the shipyard.

To the human eye, the reef balls look with concrete balls with holes, but to fish eyes, they look like a new housing development.

“These reef balls you see on the barge will construct an artificial reef designed to establish a quality habitat that will draw a variety of marine species into the coastal zone,” says Chris Morrissey, executive director of Clean Nova Scotia.

The reef balls are sunk in five to 10 metres of water so sunlight will cause algae to grow. There is potential the balls could become a hazard to small boats, so their location will be marked on marine charts.

Irving Shipbuilding is covering the cost of placing 100 reef balls in Halifax Harbour, close to Point Pleasant Park and McNabs Island.

“It’s a way to demonstrate to the public our commitment to a clean harbour,” says Kevin McCoy, president of Irving Shipbuilding.

More than a million reef balls have been placed in oceans around the world, including some in Cape Breton and some in Halifax Harbour.

Janet Stalker, the water programs manager at Clean Nova Scotia, says Clean Nova Scotia is the only agency in the region that makes reef balls.

“The reef ball itself is pH neutral so it’s not acidic. It’s not basic,” says Stalker. “It’s not going to hurt the environment in any way.”

Judy McMullen, a former program manager at the Atlantic Coastal Action Program, was involved in a similar project in Cape Breton 10 years ago.

“There’ve been several dives and the result has been great growth on the reef balls,” says McMullen. “Habitat and habitat has grown up and fish in that area.”

The reef project is Halifax is part of a requirement that allows Irving to fill in part of the harbour at the shipyard in Halifax’s north end.

“It’s part of the agreement on the loan, what we’re doing to build the facility,” says McCoy.

“Irving Shipbuilding had other options to fulfill their mandate,” says Morrissey. “This is one of the options they selected.”

The province granted the company a $260-million forgivable loan to expand and modernize the shipyard so it can cut steel on the first combat ships by the end of 2015.

McCoy says they are on schedule with the project.

With files from CTV Atlantic's Rick Grant