Canadian Scallop Die-off: Another non-native species unable to adapt?

Is Perkinsus Qugwadi (PQ) killing non-native hybrid scallops?

 

"The extreme pathogenicity of this parasite

to P. yessoensis (Japanese scallop) requires that

caution be taken to prevent the spread of this disease."

Fisheries and Oceans Canada, May 2013

Pustules in the Japanese scallop caused by PQ

 

Are Hybrid Japanese/Weathervane scallops now susceptible to the return of PQ?
The sudden die-off of scallops in British Columbia is being pointed to as another sign of ocean acidification impacting the shellfish industry. It may play a role, but acting on assumptions is dangerous and at times expensive.

Hybrids are not the same as native species
As noted on the Aboriginal Aquaculture Association website, the scallop which is currently being cultured is a hybrid between the native Weathervane scallop (Patinopecten caurinus) and non-native Japanese scallop (Patinopecten yessoensis). It is commonly called the "Pacific Scallop" and is the scallop which Island Scallops produces in its hatcheries for cultivation. The hybrid was thought to have been resistant to PQ, as the native Weathervane is. It may be that PQ has returned and the hybrid is not resistant.

Perkinsus Qugwadi disease reported again in 2011
With the disease last reported in 1997, it was thought that the non-native Japanese scallop and the hybrid had developed a resistance similar to the native Weathervane scallop. In April of 2013, however, Diseases of Aquatic Organisms published an article on the pathogen having been rediscovered in 2011 in the Japanese scallop in Canada. It is reported to be 90% fatal to juvenile scallops, less so in adults.

Holding the reins a bit tighter
It is important that agencies act on facts and not feelings when dealing with die-offs such as that recently experienced in Canada and those in the shellfish hatcheries in Washington. Ocean acidification may well be the root cause of problems currently seen. However, it may also be that attempts by an industry to create species of shellfish through hybridization and other genetic modifications which grow faster more quickly may also be the root cause. It may be wise for people riding the horse of ocean acidification to hold the reins a bit tighter.