The seas of some of the world’s poorest nations are being plundered to feed an unsustainable global appetite for farmed salmon and prawns, according to a major report.

International investigators today allege that meal made from seafood illegally or unethically caught in the Gambia, Vietnam and India is ending up in fish farmed and sold in Scotland, Norway and, especially, China. Scottish producers vociferously deny the findings of the Netherlands-based Changing Markets Foundation, the body that last year exposed links between polluting Third World sweat shops and cheap high street fashion.

But the new report, titled Fishing For Catastrophe, casts new light on a booming market for fishmeal and fish oil (FMFO), often processed by Chinese-owned mills in developing countries.

#Changing Markets said UK supermarkets were selling farmed seafood fed with meal or oil from such unsustainable sources.

However, its report aimed most fire not on retailers or even fish farmers but on the body it claims both represents and regulates meal and oil makers, the IFFO, or Marine Ingredients Organisation.

The investigation sought to map the origins of fishmeal and oil in three countries from fish to fork.

The IFFO, it said, gave assurances of the sustainability of its supply chain but investigators allege its members were engaged in illegal or unsustainable fishing.

Natasha Hurley, of Changing Markets, said: “Shoppers across the UK are totally unaware the seafood they are buying has a dark secret.

“The boom in aquaculture to match the global demand for premium seafood products such as salmon is fuelling illegal and unsustainable fishing practices that are stripping the oceans bare.

“Climate change is already destabilising our food system and that’s being exacerbated by the FMFO industry, which will take anything and everything out of the ocean to meet demand from the growing aquaculture industry.”

Scottish fish farmers say they have been using less fishmeal to feed their salmon and trout. Changing Markets believes producers must refocus on plants or face their own ruin, and that of marine eco-systems.

Ms Hurley continued: “These practices are not only destroying vulnerable marine ecosystems, but are also causing huge social issues, as communities that have been reliant on the ocean for food for generations are having their livelihoods destroyed and their access to a vital source of protein undermined.”

Chef and writer Hugh FearnleyWhittingstall has backed the Changing Markets report.

He said: “I saw for myself while making my Fish Fight programmes that fishmeal for the aquaculture industry – producing UK supermarket favourites like prawns and salmon – is being sourced in a way that is devastating to the marine environment, and to the wild fish stocks that make up much of the feed.

“It’s increasingly clear that even products certified as sustainably produced are based on aquaculture that is sourcing fishmeal in deeply irresponsible ways. “The bottom line is we need to stop taking wild fish out of the ocean to feed farmed fish, before it’s too late.”

The Scottish Salmon Producers Organisation said its members got fish from reputable sources.

A spokesman said: “Companies providing feed for Scottish farm-raised salmon have confirmed none of them uses ingredients from the Gambia, Vietnam or India or from reef fishing – the main thrust of the criticism highlighted in the report.

“Any claim or suggestion that Scottish feed suppliers are sourcing from these fisheries would be wrong, misleading and inaccurate.

“Scotland’s feed suppliers will continue to ensure their ingredients are sourced from responsible and sustainable fisheries, allowing Scotland’s salmon farmers to achieve the best feed conversion ratios of any livestock, thus ensuring best use of marine resources.”

The IFFO says its certifying wing IFFO RS is an entirely separate legal entity and rejects criticism it is both judge and lobby for the industry.

Petter Martin Johannessen, IFFO director general, said “the majority of wild-caught fish is responsibly sourced” and that a third of fishmeal and fish oil came from by-products.

He added: “Fishmeal and fish oil produced from these resources are used to provide many times more volume of edible fish through aquaculture than are consumed as raw material.

“The small pelagic fish species that form the bulk of the fisheries dedicated to fishmeal and fish oil production are a highly productive, natural resource with no, or very limited, food markets.”