They wouldn't find anything to publicise if there wasn't anything there to find. This can't be an expensive problem to fix.
You seem to have a problem with real images and facts.
Tassal seems to take these things seriously or I wouldn't invest in them. Sustainability and environmental management is part of their brand. If they forget that, their pricing and desirability is damaged.
They're asking people to pay a premium for "Clean, Australian Seafood". If their attitude is to cut corners on maintenance and the environment they're going to be toast imho. Fortunately I don't think that's the case.