The implication is not that they should be ignored because they hold a position that things are severe. If there is any implication, it is that at best they should be considered questionable until proven otherwise.
I have not been offering any concrete proof one way or the other, because I don't have any more proof than anyone else. What I have offered are possible alternative explanations for any perceived reductions in fish populations. What I have presented have been opinions only. If someone chooses to disagree with my opinions, that is perfectly alright with me. Perhaps they have some well-considered opinions of their own.
I have also tried to make it clear that it is unwise to believe everything one reads or hears. To do so is to be naive and gullible. I am surprised that anyone in your profession would have a problem with that. Anybody can spout stuff as "fact", and anyone can pose as an expert. Backing up those claims is another matter.
You have implied that you know enough about these people to remove all doubt as to the accuracy of their claims. You have been strangely silent about this. What, specifically, do you know about them?
You also say that you have not found any actual evidence that these people are wrong, but what actual evidence do you have that they are right? Are you seriously looking for evidence one way or the other, or are you willing to accept what they say because you already agree with them? If you have any evidence to support these people and their theories, then, as you say, out with it.
Hucksters come a dime a dozen, and outlandish claims need to be met with a good dose of skepticism. It's always a good idea to use one's head for more than a hat rack.
Considering your caustic sarcasm of late, I don't think you are in any position to talk to me about not moving a discussion forward.