Like I said that relies on the honesty of anglers. Also it is far easier to keep tabs on 1,000 or so pros than a million or so rec anglers. Some larger pro vessels have cameras installed so everything they do is recorded. Audits are done to check the accuracy of reporting. Trigger points are enacted if non-compliance reaches a certain level. I would be a huge job (expensive) to collate all that data from the app and it may not be any more accurate than surveys. Money might be better spent on more regular and more rigorous surveys.