I think as Pete points out, any and every development will be used to try to get Independence by the SNP.I wonder what the bigger concern is, relatively - Fish to the UK, or potatoes to Scotland?
Independence is nailed on at this point I reckon. Far too much contempt shown from Westminster these last few years (Scotland has always been an afterthought but now it's barely even that).
I would recommend inventing laws and regulations about trade in order to fool people into thinking something is happening that it isn't...they could talk about unelected bureaucrats at Westminster, types of oil that you have to legally fry your mars bars in, selling more fish to England than they buy, sovereignty of course - not being under the boot of London and a vassal state, bullying by the UK in not giving them exactly what they want...
The blueprint is there now.