Scotland's fishermen have branded attempts to mislabel and substitute some fish for cheaper varieties "inexcusable".

The comments follow studies that found the likes of cod and haddock are being replaced with cheaper fish like pollock and Vietnamese pangasius, which is farmed in estuaries in south-east Asia.

Bertie Armstrong, chief executive of the Scottish Fishermen's Federation, said the public should make clear to retailers, restaurants and takeaways that they want Scottish fish.

He said consumers expected to get what they asked and paid for, and said it was inexcusable to substitute some types of fish for others. This seemed to be happening down the supply chain, and was something all fishermen were extremely concerned about, he said.

"We believe every consumer should be asking for Scottish fish when making their seafood purchases, as it is locally caught with low 'food miles', and is also fresh and sustainable. Scottish haddock, for example, displays the prestigious flagship Marine Stewardship Council certification as being sustainably caught by fishermen using specially adapted nets that minimise by-catch and who observe real-time fishing area closures to protect stocks," he said.

"Scottish seafood is a superb and sustainable food resource with a short supply chain, and which is also healthy to eat. For all these reasons, we should therefore be consuming more of it. It is vitally important con-sumers are not put off eating fish because of mislabelling in some instances, and there needs to be proper enforcement by the appropriate authorities so as to bring to an end such regrettable practices."