Maybe I'll offer a couple of thoughts.
With respect to avoiding or preventing illegal fishing in the first place, one of the things I think is important, which we support across all of our fisheries, is a process through which we build management plans— which hopefully have understanding and, ideally, support within the fisheries being regulated by those plans—to prevent or mitigate the potential in the first place for what you're describing with regard to illegal fishing.
In the incidents where other harvesters, or the public, observe what they believe to be a violation, we do have an observe, record and report line by which members of the public can submit information about what they hear and see. That can support the ability of our conservation and protection officers to respond.
I can't speak to the individual cases you are describing in terms of what might have explained the response the department took, but as my colleagues have described earlier, there is a range of tools and approaches available to our enforcement officers for how they deal with any specific incidents or violations.