Fishing Down the Food Chain

Fishing down the food chain (also known as fishing down the food web) is a concept used to describe the process of moving away from catching large fish (because they have become too scarce) and instead targeting progressively smaller and smaller fish until eventually, when all of the fish species have been removed non-fish species are targeted. The phrase ‘fishing down the food web’ has been credited to the world-renowned French fisheries scientist Professor Daniel Pauly, whose co-authored academic paper Fishing Down Marine Food Webs coined this phrase when it was first published in 1998. As Professor Pauly has remarked, today people catch and eat the species of fish that their grandparents would have used as bait.

Tsukiji Fish Market in Central Tokyo handles 600,000 tons of fish a year. The overfishing of large predatory fish such as tuna is a major issue in fishing down the food chain.
Tsukiji Fish Market in Central Tokyo handles 600,000 tons of fish a year. The overfishing of large predatory fish such as tuna is a major issue in fishing down the food chain.

The basic idea behind fishing down the food chain is simple. In an unexploited (pristine) marine ecosystem there will be a balance between large, long-lived predatory fish such as sharks and tuna, medium-sized fish such as grouper and cod and small species which the large and medium fish prey on such as mackerel and squid. There will also be even smaller species forage species such as sandeels, herring, sprats and anchovy (which the mackerel prey on), as well as crustacean and shellfish species on the seabed. Fishing down the food chain happens when species are removed from this ecosystem in the order shown below.

Fishing down the food chain

  1. In the first stage, the very largest predators such as sharks and tuna are targeted by commercial fisheries as these are the most valuable species. As the majority of these species are slow-growing and long-lived they can be reduced in number in a very short amount of time.
  2. Once the shark and tuna numbers become too low to fish commercially the attention will shift to medium-sized species such as cod and grouper. These too will be exploited until they are reduced in number to such an extent that it is no longer commercially viable to target them.
  3. The fish next targeted are the smaller species that the cod and grouper used to prey on such as mackerel and squid.
  4. Once the mackerel and similar species have been exhausted (or reduced to an extent that it is no longer economical to fish for them) then commercial fisheries will switch to catching the forage fish which were once prey for the mackerel – small species such as herring, anchovy and sandeels.
  5. As forage fish are the smallest species of fish which are caught commercially then once they are exhausted the commercial fishing operations must switch their attention to non-fish species. These are generally crustacean species such as crabs, shrimps and prawns as well as shellfish species, all of which are likely to have boomed in numbers due to all of their natural predators being removed from the ecosystem. Since crab, prawn and shellfish are all commercially valuable the fishery may still be able to provide employment and profit and successfully disguise the fact that the ecosystem has been stripped of fish and is now only capable of supporting crustaceans and shellfish species.
  6. In some places crabs and shellfish have been fished out, leaving commercial fishermen no choice other than to scrape the final stage of the food chain and attempt to catch creatures such as starfish, sea cucumbers and jellyfish.

As Professor Callum Roberts states in The Unnatural History of the Sea, today we are likely to have around five per cent of the total number of fish that once swan in Europe’s seas when compared to pre-commercial fishing times. For large species such as sharks and skates their numbers are likely to be closer to two per cent. With such reduced numbers fishing down the food chain is set to become increasingly common as commercial fishing operations need to find new species to exploit as traditional species continue to be overfished.

The Firth of Clyde, Scotland

Main article: The Decline of the Firth of Clyde

Firth of Clyde nephrops
Crustaceans such nephrops are now the only species which are commercially caught in the Firth of Clyde.

The Firth of Clyde on the west coast of Scotland was once one of the most productive fisheries in western Europe. The relatively sheltered waters attracted a multitude of species, but it was the herring fishery which formed the backbone of the fishing industry and provided plentiful employment for those living in and around the Clyde. A ban on bottom trawling introduced in the 1800s meant that the marine environment was protected from over-exploitation and the stocks of all species remained healthy. However, the increasing efficiency of fish-catching vessels meant that fish stocks in the Clyde were starting to show signs of depletion by the middle of the twentieth century. While this should have seen fish stocks given greater protection and signalled a reduction in fishing intensity it was instead agreed in the 1960s that the bottom trawling ban would be lifted, meaning that demersal fish such as cod, haddock and flatfish could now be fully exploited. While a ban on trawling within three miles of the shore was originally put in place this was lifted shortly after, and the entire Firth of Clyde was open to commercial fishing.

This had the effect of depleting the remaining stocks of large demersal fish, while numbers of the pelagic (mid-water) herring also dropped dramatically, meaning that it soon became impossible for the Clyde to support a fishery which relied on catching finfish. While the number of fishermen employed in the area shrank dramatically those who remained did were forced to begin fishing down the food chain. They switched from targeting fish and instead began catching crustaceans – mostly nephrops (a lobster species also known as Dublin Bay prawn or scampi) and crabs and lobsters. This type of fishing requires heavy gear and fine mesh nets to be dragged along the seabed, further damaging the marine environment and preventing the chances of the cod, haddock and plaice stocks from rebuilding. Today 98 per cent of the commercial catch in the Firth of Clyde is made up of crabs, lobsters and nephrops, and the only finfish found in the area in any meaningful numbers are small, immature whiting as well as a brief run of summer mackerel. The Firth of Clyde is a perfect example of intensive commercial fishing operations completely changing an ecosystem and commercial fishermen being forced to fish down the food chain in order to find new species to catch.

The Grand Banks, Canada

Main article: The Collapse of the Grand Banks Cod Fishery

The Grand Banks off the coast of Newfoundland, Canada was, for hundreds of years the most productive cod fishery on planet earth. Scientists now estimate that in the late 1400s when explorers first arrived there was a spawning cod biomass of around seven million tons. Beginning with steam-powered trawlers in the 1920s and then factory vessels in the 1960s the Grand Banks were fished intensively for most of the twentieth century. In the early 1990s it was finally realised that Grand Banks cod stocks were undergoing a collapse, leading to a moratorium on cod fishing being imposed in 1992 and extended indefinitely two years later.  Despite this, the Grand Banks have yet to return to a fraction of their former productivity, and a fishery which produced catches of more than 800,000 tons in the 1960s now, with the small amount of commercial fishing that is permitted, produces around 15,000 tons.

Commercially caught snow crabs.
Crustacean species such as snow crab have replaced cod as the commercial catch in the Grand Banks.

While the complete collapse of cod stocks has been an economic and ecological disaster, the absence of cod has seen the numbers of crab, shellfish and shrimp increase as cod were their natural predators. This has allowed a fishery for shellfish and crustaceans to develop in Newfoundland, although it is much smaller than the cod fishery of the twentieth century. While this new fishery appears to be well-managed and has even been awarded MSC (Marine Stewardship Council) certification, it is an example of fishing down the food chain, as it is the once-ignored shellfish and crustaceans which are now the target species. There are also concerns that a fishery dominated by shellfish and bottom-dwelling crustaceans can never be healthy, and were the crab fishery to collapse then the region would again be plunged into economic and social turmoil.

Georges Bank, USA

Main article: The Decline of Georges Bank Fishery

Georges Bank is an area of raised seabed located around sixty miles off the coast of New England. Like the nearby Grand Banks, it was an area which once produced huge numbers of fish, but poorly-managed commercial fishing throughout the twentieth century meant that stocks of commercially valuable fish have collapsed and fishermen have been forced to catch species that they once ignored or saw as pests.

In the book The Unnatural History of the Sea Callum Roberts explains how commercial fishermen on Georges Bank targeted premium whitefish such as cod, haddock and flounder. When these species began to decline in the 1970s catches became dominated by smaller species such as dogfish and rays. Fishermen were initially horrified that low-value species were becoming the most common species across Georges Bank, but with fewer predators present their numbers continued to grow and by the 1980s, dogfish and rays were at eight to ten times the abundance of whitefish.

With little else to catch the New England fishermen turned to catch these species. As Roberts states:

“[Small] sharks and rays with their tough and stringy meat are poor substitutes for succulent flaked haddock or cod. But necessity gave them a market.”

But by the mid-1990s even these species were declining in number as they became overfished. A new species was needed but this was not to be fish. Instead, fishermen turned to sea urchins which had exploded in numbers as the fish which once ate them were now absent. With international markets for seafood opening up across the world, a number of New England fishermen managed to make a living from catching sea urchins and exporting them to Asia where they were a popular food. From cod and haddock to dogfish and rays and finally, to sea urchins, Georges Bank provides a perfect example of fishing down the food chain.

UK and European Species

The declining numbers of once common commercial fish such as haddock and cod have led to retailers having to move to species which still have healthy stocks due to being further down the food chain, meaning they have mostly been ignored as commercial species. While it is fairly common to see whiting on sale in fishmongers and supermarkets now until relatively recently they were of very little commercial value and were either discarded at sea or only retained to be either reduced down to fishmeal or used in pet food. Now the lack of premium whitefish such as cod and haddock has seen whiting acquire a new reputation and a growing value as a commercial fish. The same is true of pouting – a fish which just a few short years ago was practically worthless but is now increasingly common both on both wet fish counters and as the fish used in ready meals and other fish products. Fishing industry website Seafood Source released an article which said that Tesco supermarket declared the species to be an “overnight success” when it was sold for the first time in its stores in 2011.

Gurnard is another species which has had its reputation completely transformed. Previously discarded at sea or used as bait in crab and lobster pots it could only raise a price of around 25p a kilo at the start of 2007. A year or so later gurnard were finding their way into supermarkets and fishmongers as a food fish. This was quickly followed by celebrity chefs featuring gurnard on TV shows and in recipes in cookbooks and by the end of 2007 the price of gurnard had reached £4 per kilo and sales were up 1000%, showing the speed at which the reputation of a fish as a food can be turned around. Even the most unattractive species can be re-branded to sell in place of more traditional food fish. In February 2016 Norwegian fish exporting company the Lerøy Seafood Group stated that they were investing money in re-branding lumpsucker fish so they could be exported and sent to Asia as a food fish, while Irish fishmongers have attempted to sell the unusual greater forkbeard species to consumers under the somewhat unappetising name of ‘Sweaty Betty.’

Switching to different species is often presented as being a success story which is good for overall fish stocks as it takes the pressure off overfished species (this is something which campaigns such as Hugh Hugh Fearnley-Whittingstall’s influential Fish Fight campaign promoted). However, the reasons why species like cod and haddock have been overfished are never questioned, and the reality is that if commercial fishing continues in its current form it is only a matter of time before stocks of newly valuable species such as pouting, gurnard and whiting themselves become overfish and decline in number. At this point, commercial fishermen will have to find a new target species which is even further down the food chain.

Sea Angling and Fishing Down the Food Chain

Evidence of fishing down the food chain can be seen in sea angling. LRF (Light Rock Fishing) is a development in sea angling where anglers use small, light rods that can cast lures weighing less than one gram to catch mini species such as rockling, blennies, gobies and sea scorpions.

Mini Species
Mini species which were once ignored by anglers are now caught using LRF methods – a case of anglers fishing down the food chain.

While this type of fishing is both fun and highly enjoyable it has developed due to the declining numbers of larger fish which anglers traditionally targeted such as cod, bass and ray species. While many anglers continue to target larger species as well as taking part in LRF, there can be no doubt that the expansion of Light Rock Fishing is a form of fishing down the food chain whereby anglers are having to turn their attention to smaller species due to the lack of larger fish which they originally targeted.

The Future: Jellyfish Sandwiches?

Fishing down the food chain has led to some previously unthinkable species being targeted for human consumption. Once the large and medium fish species, smaller forage fish and crustaceans and shellfish have been removed from an ecosystem commercial fishermen must move even further down the food and seek out non-fish species to catch. Daniel Pauly himself states that people in the developing world have seen their seas emptied by commercial fishing operations from rich nations and have therefore been reduced to eating sea creatures such as sea urchins and sea cucumbers due to the lack of fish.

Worldwide jellyfish catchWestern nations have also been forced to look for new non-fish species to catch in their own waters in order to keep their fishermen in employment. As predatory fish have been removed from the sea the number of jellyfish has increased significantly in recent years. This has led to some fishermen in both Europe and America targeting jellyfish commercially and there is now a fishery in the US state of Georgia where cannonball jellyfish are caught and then processed at a specially converted plant on shore.

Jellyfish and noodles
Cannonball jellyfish (Stomolophus meleagris), left, is caught in US waters and turned into a noodle like food, right.

The vast majority of jellyfish processed at this facility are dried and exported to Asia where they are used in soups and salads, or can be rehydrated and eaten as a noodle-type food. It remains a real possibility that jellyfish fisheries could expand and jellyfish could become an increasingly common food in developed nations in Europe and North America.

Prof. Daniel Pauly
Prof. Daniel Pauly

The only answer is to reduce commercial fishing to sustainable levels and allow the full range of species which make up marine ecosystems to rebuild their numbers back to something approaching the levels they were at before industrialised commercial fishing began in the 1950s. Anglers must also play their part by protecting the marine environment and returning endangered species and those fish which are not being kept to eat. In many parts of the world fishermen have already fished so far down the food chain that they are approaching the end point where soon there will be absolutely nothing left to catch.

As Daniel Pauly states:

“When we first presented this, it was a joke – you’re going to have a jellyfish sandwich … It was a joke, but now it’s real … We really are headed for trouble.”