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Halifax ? Scientists will begin probing waters off Nova Scotia in search of a slimy creature they believe is slithering north and could be blanketing some of Canada's richest fishing grounds.
Researchers from the U.S. Geological Survey plan to head out Monday to a vast area over the Canadian portion of Georges Bank to look for a colony of sea squirts nicknamed the Blob for its icky texture and habit of covering most everything in its path.
?It's something new. It covers up the bottom and it forms a barrier between fish and what fish feed on, so logically you'd think it could be a problem,? Page Valentine, a scientist with the agency, said from his office in Woods Hole, Mass.
?At some point it could get so pervasive that everybody will realize we've got a problem out there and it'll be too late.?
Dr. Valentine accidentally discovered the organism, a simple tunicate with no skeleton that filters plankton, in 2002 on the U.S. side of Georges Bank, a rich fishing area between Nova Scotia and Maine. He returned in 2003 and found that it was covering an area of at least 15 sq. kilometres.
One year later, a thick carpet of the porridge-like goop had spread over more than 104 sq. kilometres.
The creature, which measures one to two millimetres individually, attaches itself to rocky bottoms and proliferates rapidly until it creates a sometimes huge carpet that can come between various fish species and their food.
The fear is that it could also interfere with the scallop fishery, one of the most vibrant and lucrative on Georges Bank, by disrupting the resting ground for scallop larvae.
?The implication is that if this organism was limiting space for larvae to settle, then that would limit the amount of habitat for these larvae and that would not be a good thing,? said Dr. Valentine.
It's not clear how much of a threat the unique life form poses to lobster, herring, swordfish, groundfish and tuna stocks, but it could be difficult to slow or control since it has no known predators.
Dr. Valentine discovered through experiments in his lab that the tunicate can form new colonies after being disrupted. For example, if a trawler swept over a colony and picked up pieces, it could easily be spread to other areas.
So far, the tunicate, whose scientific name is didemnum, been found in British Columbia, New Zealand, the Netherlands, France, California and the eastern U.S. seaboard, but scientists haven't determined if they are all the same species.
Similar tunicates have attacked several shellfish operations around the world, including ones along Nova Scotia's south shore and in Prince Edward Island, by glomming on to mussels and oysters and killing them in large numbers.
Dr. Valentine plans to deploy camera systems to take videos and still pictures of the area. He will also collect samples of the tunicate, if they find it, and fish to determine if certain species are feasting on it.
Canada's federal Department of Fisheries and Oceans isn't involved in the research, but will likely pay close attention to Dr. Valentine's findings.
?The main thing is that fisheries managers need to know about this so they can decide whether this is a threat,? Dr. Valentine said. ?It certainly is a threat in aquaculture.
?It remains to be determined if it is a threat in offshore fishing grounds. But I don't think it's going away.?
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