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Must admit I wasn't up to speed with the lights for specific fishing activities - but that one's still not applicable (blaming the skipper, not you) since the net clearly isn't caught on the bottom in the picture.
That might explain the unusual looking approach to hauling the net, don't they normally drag it in over the stern?
I confess to know naff all about trawling but they must snag a fair bit, it is after all not very dissimilar to anchoring. I would imagine switching the lights over would be the last thing you get around to doing.