Playing fast and loose with the future of the Scottish fishing fleet and Scottish waters is not good politics yet that is what Alex Salmond did in Bruges this week.

Knowing full well the considered view among the great majority of policy makers in Brussels is that an independent Scotland will not automatically become a member of the EU and will have to apply to join and face the prospect of tortuous negotiations, the First Minister raised the possibility of foreign boats being denied access to Scottish waters and, as a consequence, access to Norwegian waters if the way was not cleared for an early Scottish entry.

As he said himself, this is clearly absurd. So why he raised this in the first place? Does he think the bureaucrats of Brussels would roll over, tear up the rule book, and make an exception of Scotland because he made threatening noises?

Having endured too many all-night sittings on the European circuit as officials and politicians wrestled over a paragraph, I know it is the prospect of a new applicant to the EU being accepted in 18 months that is absurd.

And it is neither diplomatically nor politically sensible to hold a gun to the head of member states of the EU.

The Spanish and Portuguese fishermen will have recoiled in horror before it dawned on them they would be entitled to free passage to Scottish waters for vessels passing en route to Norwegian waters under international law, even if Scotland split from the UK.

Regardless of the shock and concern in the ports of Cadiz and Porto, it would be nothing compared to the indignation and horror of the fisherman back home: on Whalsay, in Grimsby, Peterhead and Fraserburgh, Ullapool and Lochinver; wherever fishermen earned their living.

Even if it were possible to ban foreign fishermen from Scottish waters, Scottish fishermen would know that banned countries might play tit-for-tat and ban Scottish fishermen from their waters and, importantly, access to European markets. Large areas of the North Sea and the Irish Sea would be no-go areas for the Scottish fleet.

Bertie Armstrong, chief executive of the Scottish Fishermen's Federation who demanded an explanation from Mr Salmond, knows the stakes are high and that fishermen from the north east of Scotland in particular depend on the fish resources of other countries.

For the fragile communities of the west, the isolation of the Scottish fishing fleet in Europe would have dismal consequences.

An already depleted industry would face even greater pressure if the large, hugely capitalised boats became dependent on the prawn fishery of the Minch.

And there is no historical evidence to suggest that the bigger, more expensive boats of the east coast would indulge the smaller boats on the west.

Scottish waters, like the waters of every other country, are governed by international law.

There is, however, not such a thing as Scottish fish since fish do not recognise political borders. It is imperative, however, that fish, wherever they swim, are protected.

National management schemes cannot work and this would spell disaster for fish stocks, thereby threatening fishing and fishing-dependent communities.

Fishermen and marine scientists know this. It is why international treaties exist and why they are important to every fishing community in Europe and beyond.

Fishing have always been an emotive issue, not least because a great deal of money is at stake. It is not so long ago (1976) since the furore over cod brought two countries, and two Nato allies at that, to the brink of war.

Icelandic costguard vessels cut the nets or British trawlers and there were numerous violent incidents between Icelandic ships and British trawlers.

It is genuinely difficult to work out Mr Salmond's attitude to the EU. He wants Scotland, if broken away from the UK, to join up but he wants the rules changed to meet his demands.

The delicate subject of fish is but one of the issues.