Where do Fish Really Come From?
We all love to dig into vast platters of velvety gravlax, satisfying chippy cones, or a basket of coconut shrimp, not to mention the comforting creaminess of homemade tunafish sandwiches. But the real question underlying all these treats of the sea: where are these tasty fish really coming from? Unfortunately, it’s a little more complicated than “from the sea with a great big net.”
Fish either come from the sea (wild caught), or they are farmed (aquaculture.) Globally, seafood production reached 171 million metric tons in 2016, and on average ~17% of animal protein consumed globally comes from seafood (this number can be much higher for coastal communities.)
In its most basic terms, fishing is accomplished by net, line or trap. This gear can be mobile (active) or static (passive), depending on whether they are towed across the seabed or are fixed to it. Active gear includes any trawls, trolling and drifting nets or lines whereas static gear includes fixed nets, traps and rod and line. The environmental impacts of these nets, traps, and fancy fishing gear varies from extremely destructive (trawls and trolls) to minimally damaging (pots & hand-line.) In general, static / passive gear has a lower impact on the seabed.
And these commercial fishing methods aren’t occurring in a delicate way either. Currently, at least 30% of large commercial fish stocks are currently classified as overexploited. And although this proportion is actually an improvement over previous decades, for many regions of the world — particularly less economically stable countries with small-scale fisheries — the sustainability status of fisheries and even the amount of fishing actually occurring is uncertain, as management remains mysterious or non-existent.
A great intro to fishing practices & the dangers of overfishing.
AN ILLUSTRATED GUIDE TO FISHING METHODS
To help you have more clarity about what’s happening in the deep blue, I have outlined the most common fishing methods below, breaking them down into three groups depending on how they impact the ocean habitats & ecosystem, and how much bycatch occurs:
-THE Traditional (lower impact)
-THE So-So (varying impact)
-THE Nasty (highest destructive impact)
*Please note: these impacts vary depending on where they’re occurring, how intensively the area is fished, and how well the fishery is managed. *
THE TRADITIONAL METHODS
In general, these lower-impact static methods are less destructive to the marine habitat & wildlife within their range.
They are the most sustainable methods of gathering marine life.
HAND LINE: a single fisherman dangling a line off of their moving or stationary boat. catch is of very high quality, as it’s live when caught. Some larger vessels have mechanized systems to help with hauling in the catch. Overall, on a small scale, it’s a selective & sustainable method.
Species targeted: a vast variety of species around the world! Cod, mackerel, tuna, grouper, snapper, and even squid (with jiggers attached.)
Problems: very few on such a small scale.
POT & TRAP / CREEL: small baited traps which can be set out to catch fish & crustaceans. Potting is a highly selective method of fishing, since the catch is brought up alive, and sorting takes place immediately, allowing unwanted animals to be returned to the sea, making the method potentially sustainable
Species targeted: lobsters, crabs, whelk, and octopuses.
Problems: modern pots and traps are constructed from plastic-coated or galvanized wire with nylon netting, making them virtually indestructible, which is great for efficient fishing, but less so for giving the marine critters a chance to escape. Pots can also detach and float away, becoming a hazard for entanglement, particularly for whales.
How to make it better: Culling rings may be added to a section of a trap or pot to allow undersized animals to escape, but this approach does not minimize injury to marine mammals or turtles. Instead, “weak links” and “breakaway lines” are modifications that can allow an animal to break free from the gear and reach the surface to swim away with minimal trailing lines. The use of sinking ground-lines between traps also minimizes the risk of entanglement. Reducing the number of buoy lines in the water column by trawling up, or adding more traps per trawl, should reduce risks to protected species.
DIVER FORAGED: Free divers head to the bottom of the sea to gather edible creatures. its impact is low, and it’s potentially one of the most species selective and least damaging fishing methods, provided harvesting is carried out responsibly.
Species targeted: geoduck, sea cucumbers, urchins, scallops, barnacles, rock lobsters, abalone, grouper and reef fish.
Problems: this method is sustainable as long as the marine habitats have foraging limits.
THE SO-SO METHODS
These fishing methods have higher impacts on the ocean ecosystems, but if they are well-managed, their destructiveness can be controlled.
DREDGING: A dredge is a metal framed basket with a bottom of connected iron rings or wire netting called a “chain belly.” The lower edge of the frame has a raking bar, with or without teeth, depending upon the species targeted. The catch is lifted off the seabed by the (toothed) raking bar and passes back into the basket or bag. Depending on the size of the boat and the depth of water fished, the number of “dredge bags” may be up to 10 per side.
Species targeted: oysters, clams, mussels, conch, sea cucumbers, crab, scallops.
Problems: Dredging rips up the seafloor, but the environmental impact varies significantly depending on the type of sediment on the seabed and the habitat it supports. Sea turtles and marine mammals can also be injured.
How to make it better: in shallow water, diving or using rakes, shovels, clam tubes, and tongs can be used to reduce seafloor damage. However, there are no economically viable alternatives in deeper water, so habitat protection measures are important. Vessels in the Atlantic Sea Scallop fishery are required to use turtle deflector dredges in certain areas and seasons, which block the entrance to the dredge and deflect turtles over the top of the frame. Additionally, these vessel operators must also install chain mats at the opening of the dredge collection bags to block turtles from the entrance.
FIXED (GILL) NET: Gill netting is probably the oldest form of net fishing, having been in use for thousands of years. They catch fish that attempt to swim through the net, which are caught if their heads can pass through the meshes but not the rest of their body, so the fish becomes entangled by the gills as it attempts to back out of the net.
Species targeted: monkfish, turbot, bass, crawfish, Pollack, barracuda, spider crab, hake, saithe, ling, Cod and red mullet.
Problems: Techniques such as wreck netting and netting over rocky reefs can also result in snagged or lost nets. Lost nets can continue to fish and are often termed ‘ghost nets,’ and pose a real threat to marine life. There is also a big risk to larger marine animals such as dolphins, porpoises, sharks, rays and seals. Monofilament nets are very difficult to see when they are in the water, and these creatures can get accidentally caught in the nets.
How to make it better: Acoustic deterrent devices known as ‘pingers’ have been developed to significantly reduce the risk of bycatch by emitting a regular sonic noise which scares cetaceans (dolphins, porpoises and whales) away from nets. Use of “pingers” is now a legal requirement for all netting vessels over 10m in length, however smaller vessels are not yet required to use pingers.
PELAGIC TRAWL: Trawling is common worldwide due to its efficiency in capturing large numbers of fish. “Pelagic” means the trawling is focussed in the mid zone of the ocean.
Species targeted: sea bass, mackerel, Alaskan pollack, redfish, herring and pilchards.
Problems: Pelagic trawling affects marine mammals, as they are caught accidentally when feeding on the same fish being targeted by fishermen. Animals can remain conscious for some time while struggling in the net, causing suffering and injuries such as lacerations and broken teeth and bones, before dying of suffocation.
How to make it better: In response to the continuing slaughter of dolphins in pelagic trawl nets targeting sea bass and other species, the UK Government is developing a marine mammal escape device which, if successful, will reduce the number of dolphin casualties in these fisheries.
DRIFT (GILL) NET: Drift nets are gill nets that are allowed to drift with prevailing currents.
Species targeted: Drift nets are used on the high seas for the capture of a wide range of fish including tuna, squid and shark, and off north-east England for salmon. In Cornwall, they’re focussed on sardines & herring.
Problems: Much like the fixed gill net (above,) they’re highly unselective, so there’s a big risk of bycatch. Drift gill net fisheries in the Mediterranean for swordfish and albacore tuna pose a particular threat to striped dolphins.
How to make it better: Some fisheries must use “pingers”: acoustic alarms attached to nets, which deter marine mammals. It should be a requirement for all gill-netters to use these.
PURSE SEINE NET: This is the general name given to the method of encircling a school of fish with a large wall of net. The net is then drawn together underneath the fish (pursed) so that they are completely surrounded. Finally, the fish are scooped out and into the boat using “brailers”. It is a very efficient and aggressive fishing method, and aims to capture large, dense shoals of mobile fish. Ring nets are similar on a smaller scale, and are used in Cornwall to catch small schooling fish.
Species targeted: sardines, mackerel, anchovies, tuna, and herring.
Problems: Purse seining is a huge cause of overfishing due to its unselective nature. Purse seining for yellowfin tuna in the Eastern Tropical Pacific, specifically ‘dolphin-fishing’, where dolphins are deliberately encircled to trap the tuna swimming below them, is probably the most widely reported example of marine mammal by-catch. However, since the introduction of legislation to protect marine mammals in 1972 (Marine Mammal Protection Act) the number of yellowfin tuna taken in nets set deliberately on dolphins now only accounts for a very small proportion (3.3% in 1997) of tuna on the world market. Purse seines can also be used to catch fish congregating around fish aggregating devices (FADs), which in turn result in greater numbers of bycatch animals, and sea turtle and marine mammal entanglement.
How to make it better: Avoid the use of FADs, and avoid the time spent in the nets by the fish. Use encirclement methods that avoid harm to cetaceans. Use gear modifications shown to reduce bycatch, such as sorting grids, without killing the escaping fish.
THE NASTIER METHODS
These fishing methods are the harshest on the marine environments and the creatures that live there…
THEY NEED much more thorough MANAGEMENT in place to reduce their impacts.
POLE & LINE: Pole and line fishing (also known as bait boat fishing) is used to catch naturally schooling fish which can be attracted to the surface, like tuna. The method almost always involves the use of live bait (anchovies, sardines etc), which is thrown over board to attract the target species near the boat (chumming.) Poles and lines with barbless hooks are then used to hook the fish, and they are “gaffed” (impaled) to bring them on board. Pole & line is a more selective technique that purse seine nets, which historically have also been used to fish tuna.
Species targeted: tuna (skipjack and albacore)
Problems: live bait fish are used to “chum” the water, and chumming can attract other creatures that also get caught in the fishing gear, particularly dolphins and whales. If it was well-managed, it would be a most sustainable method.
How to make it better: Using circle hooks on longlines can reduce bycatch of turtles, while attaching streamers to lines can reduce bird bycatch. Using harpoons, hand lines, greenstick or buoy gear instead of long lines are more sustainable options that have proven to reduce bycatch. Avoid the use of live bait fish.
ELECTRICAL FISHING: Pulse trawling is a technologically advanced – but highly controversial – method of commercial fishing - an electrified form of Beam Trawling. A net is dragged across the seabed by a trawler and the mouth of the net is held open by a solid metal bar with ‘tickler chains’ thrashing the seabed in front of the net. This stirs up fish (especially flatfish and prawns, which bury themselves under the sand and silt of the seabed) which then allows the fish to be scooped into the net. Although it remains to be seen: pulse trawls are apparently up to ten times lighter than traditional beam trawling gear, meaning that fishing with pulse gear uses much less fuel than beam trawling
Species targeted: prawns, various flatfish
Problems: Fish death through electrical shock. Habitat destruction & bycatch. Beam trawling, (which this method is structurally based around), is considered one of the most environmentally destructive forms of trawling by environmental groups such as Greenpeace due to the very high levels of bycatch and the damage caused to the seabed by this type of commercial fishing. This pulse trawling method replaces the tickler chains of traditional beam trawling with a series of electrical drag wires. These wires send electrical pulses into the seabed which cause the muscles of fish to contract which forces the fish upwards out of the seabed and into the net.
DEMERSAL OTTER TRAWL: Demersal/ bottom trawling covers several gear types that are dragged along the seabed. These nets are towed by one or two boats and are designed to catch fish living at great depths or on the bottom of the sea. The forward part of the net – the ‘wings’ – is kept open laterally with “otter boards” or doors. Fish are herded between the boards and along the spreader wires or sweeps, into the mouth of the trawl where they swim until exhausted. They then drift back through the funnel of the net, along the extension or lengthening piece and into the “cod-end,” where they are stored until they’re collected.
Species targeted: bass, bream, cuttlefish, gurnard, haddock, hake, john dory, monkfish, mullet, octopus, plaice, pollack, prawn, shrimp, sole, whiting
Problems: The gear has a massive impact on seabed habitats & marine life. As they’re very unselective, the trawls can reduce biodiversity and productivity of the habitat, particularly when used for the first time in a new area. Trawling and tropical shrimp trawling account for 55% and 27% of all global discarded bycatch respectively. This type of trawling especially poses a threat to rare species of sharks, skates and rays such as Angel sharks and Long-nosed skate.
How to make it better: Trawl gear may theoretically be made more “selective” by modifications called bycatch reduction devices (BRDs.) These work by allowing unwanted species to escape though holes in the net while retaining the target species. But for this gear to be truly selective, the fish escaping must be sufficiently unharmed to survive. Another method of bycatch reduction is to reduce fishing effort, e.g. by closing a fishery at a particular time and place when bycatch levels are particularly high. They could also reduce the duration of the trawl, and handle the bycatch better, so it’s more likely to survive. The use of Turtle Extractor Devices (TEDs) help sea turtles and sharks escape from trawls. Unfortunately, they’re currently only required in a few selected fisheries, but NOAA is working to get their use more widely spread in the trawl fisheries.
LONGLINE: one of the most fuel-efficient catching methods, long-lining is used to capture both pelagic fishes (like tuna) and demersal (like flatfish.) It involves setting out a length of line, possibly as much as 80-100 km long, to which short lengths of line, or “snoods,” with baited hooks are attached at intervals. The lines may be set vertically in the water column, or horizontally along the bottom. The size of fish and the species caught is determined by hook size and the type of bait used.
Species targeted: swordfish & tuna. In deeper water: cod, rockfish & flatfish.
Problems: Although a selective method of catching fish, long-lining poses one of the greatest threats to seabirds. Species such as albatross, petrels, shearwaters and fulmars scavenge on baited hooks, get hooked, are dragged underwater and drowned. Also at great risk are vulnerable sea turtles and sharks.
How to make it better: Using circle hooks on longlines can reduce bycatch of turtles, while attaching streamers to lines can reduce bird bycatch. Using harpoons, hand lines, greenstick or buoy gear instead of long lines are more sustainable options that have proven to reduce bycatch. Avoid the use of live bait fish.
TROLL: Towing baited hooks or lures through the water. Particularly suited to the capture of pelagic species of high individual value.
Species targeted: tuna (albacore and skipjack), wahoo, Dorado/ Mahi mahi, barracuda and salmon.
Problems: While there are low levels of bycatch, the trolled hooks are a great threat to seabirds. Troll-caught salmon have been shown to be severely exhausted when landed.
How to make it better: Avoid the use of live bait fish. Monitor the gear, and land fish as soon as they are caught. Use circle hooks that cause less injury to the fish. Avoid gaffing fish. Ultimately, use a more selective, static fishing method.