The cost of fish in the United Kingdom is largely due to a combination of controlling fish stocks and the cost of operating a fishing fleet. The waters surrounding the UK have been overfished, leading to a decrease in the size of catches. This is because people all over the world are consuming more and more fish. On average, British people eat 20 kg of fish per year, meaning that imported fish is necessary to meet demand.
If the UK were to rely solely on fish caught in the country each year, supplies would run out by July. This problem is even more pronounced in other countries, such as Spain and Portugal, where people eat two to three times as much fish as British people. In short, demand for fish is increasing while stocks are declining, resulting in higher prices worldwide. Additionally, the UK imports almost twice as much fish as it exports, with cod, tuna, shrimp, salmon and haddock being the five main types. Researchers have found that a hard Brexit would make these imports more expensive.
This would also affect UK fish farms, which export most of their products, and the fish processing industry, which depends on imports. For most freshwater fish, such as carp, you'd have to go to a wholesale market like Billingsgate in London. There isn't much retail market for them, so they're usually not found in stores; perhaps in communities that tend to eat them. The impact of a hard Brexit on trade would cause an increase in the cost of imported fish. This would also affect UK fish farms and the fish processing industry, both of which depend on imports.
In addition, it would lead to a decrease in incomes for UK fishermen. Every morning, Nick Jesse is in his tent at 3am ready to unload fresh fish brought in wagons from ports across the UK. He has been working in the family business for 40 years. Previously, illegally caught fish entered the market, as did blackfish (fish that exceeded the quota and were caught and not reported; see the Scottish blackfish scandal). The EU countries that would be most affected by the end of access to UK waters according to analysis were Ireland, Belgium and the Netherlands, whose fishing fleets catch between 35 and 45% of their fish in the UK.
And despite what has been said about selling fish from the UK in the EU, there isn't a single fishmonger or supermarket I've visited in Spain that sells fish from the UK. The increase in price of fish can be seen as either positive or detrimental for fish stocks depending on how it is managed. Charles Clover, columnist for The Sunday Times and author of The End of The Line, says that effective measures to stop illegal fishing have been one of the causes of rising prices.