All those fisherman are experienced. You're a lot safer with their observations and tests than "good enough for government testers".
I agree (we wouldn't sell anything we wouldn't eat ourselves when I held a commercial fishing license), and as far as I am concerned, the desire of seafood vendors and fishermen to avoid the consumption of or liability for a tainted product and the personal or market damage that would bring is quite likely to be enough to ensure the safety of the seafood.
Independent tests would not be conducted by either government nor oil companies, but by those with a vested interest in a safe product, or consumers.
It is just that those tests have not seen much--if any--coverage in the media, only the 'official' ones get press.