Scottish mussels arent a different species, well the one in farmed packets aren't supposed to be, however there is problem. The ordinary mussel is the blue mussel [mytilus edulis], good strong shell with nice meat and reasonably easy for shelf life to be preserved, there is also the bay mussel [mytilus trossulus] which although can be eaten have thin shells, much worse shelf life and are more prone to contamination. The bay mussel has led to farms in some scottish loughs to be abandoned. Whatever species these were the smell was appaling, they were tasteless and the flesh was crumbly. The meat was also half the size expected of the shell size. The shells were glass like, transparent and breaks with very little pressure. The bay mussel are probably fine straight of the sea, but aren't suitable for the the food industry.
We contacted the local food inspectors from the council which will get back to us, the shop gave us a refund [but did offer a direct replacement!!!!] , and the firm was polite when rung up. The shop didnt have a manager on duty, and didnt remove the product from sale. The shopp supervisior was informed that the local council food health had been informed and the company had been contacted. I honestly think these mussels are contaminated enough to be very dangerous, she dint seem to grasp they might be selling something unfit for human consumption. OK farmfoods most their stuff isnt that edible, but it shouldn't kill you.