The SP drop makes no sense - it was a dramatic drop and that's for sure but it doesn't seem to be anything specific about Tassal because if it was you'd think it would out there by now. Whether it is the weather or whatever else it is I don't see anything that it is a long term problem because the actual business itself seems to be in great shape.
I also think it looks like a red hot buy at the moment and if I wasn't already a bit overweight in it I'd be keen to top up and reduce my average. Either way I'm not losing any sleep over the SP and remain more than happy to hold.