Trawling Vessels: What Boats Use Trawl Nets?

Trawlers, or draggers, are boats used for trawling, an industrial method of fishing that involves pulling a fishing net, or trawl, through the water behind one or more boats. Trawlers vary in size from small open boats with 30 horsepower engines to large factory trawlers with over 10,000 horsepower. Trawling can be carried out by a single trawler or by two trawlers fishing together (pair trawling). Trawls can be categorised based on where they sample the water column: surface, midwater, and bottom trawls. Midwater trawling is often used to catch pelagic fish, while bottom trawling targets both bottom-living fish and semi-pelagic fish.

Trawlers are large vessels that catch midwater species like pollock and bottomfish like flounder

Trawlers are vessels that use a trawl, a net to catch fish, which is pulled along the bottom of the sea or in midwater. Trawlers can be small open boats with as little as 30 horsepower or large factory ships with over 10,000 horsepower. The larger trawlers are often called factory trawlers and can be up to 600 feet in length. They possess onboard processing facilities and are used for commercial fishing.

Trawlers catch large quantities of midwater species like pollock and bottomfish like flounder. They use a large, cone-shaped net, with "doors" on either side of the net's opening to hold it open. Some trawlers also have a heavy chain along the bottom of the net's opening to keep it close to the seafloor. The net is retrieved using winches and a power drum, which the net is rolled onto as it is brought onto the trawler. The end of the net, the "bag" or "cod end", holds the fish and is usually pulled up a slanting stern ramp at the back of the trawler.

Trawlers can catch enormous quantities of fish, with a 2-hour tow of the net yielding up to 100 tons or more. The trawl fishery processes its catches into fillets, as with flounder, or minced fish called "surimi", which is used for fish sticks and similar products. Trawling can be done by a single trawler or by two trawlers working together (pair trawling).

Trawling can be divided into bottom trawling and midwater trawling, depending on the height of the net in the water column. Bottom trawling involves towing a large net with heavy weights along the seafloor, which scoops up everything in its path. Midwater trawling uses funnel-shaped nets and is used to catch pelagic fish, which live in the upper water column of the ocean. Midwater trawling is generally used to catch a single species of fish, whereas bottom trawling targets both bottom-living fish (groundfish) and semi-pelagic fish.

Trawls can be surface, midwater or bottom trawls

Trawling is an industrial method of fishing that involves pulling a net through the water behind one or more boats. The boats used for trawling are called trawlers or draggers. Trawlers vary in size from small open boats with as little as 30 hp (22 kW) engines to large factory trawlers with over 10,000 hp (7.5 MW).

Trawling can be divided into three types: surface trawling, midwater trawling, and bottom trawling. This classification depends on how high the trawl (net) is in the water column.

Midwater trawling, also known as pelagic trawling, involves towing a large net through the middle of the water column. Midwater trawls are designed to catch pelagic fish, which live in the upper water column of the ocean. This type of trawling is often used to catch a single species of fish, such as mackerel, herring, or hoki. Midwater trawls do not come into contact with the seabed, which reduces the risk of damaging marine habitats. However, this method can still result in the accidental capture of non-target fish species, leading to potential population impacts.

Bottom trawling involves towing a large net along the seafloor (benthic trawling) or close to it (demersal trawling). This method is used to catch both bottom-living fish (groundfish) and semi-pelagic fish. Bottom trawling uses a net with heavy weights that scoops up everything in its path. One disadvantage of bottom trawling is that it can stir up significant amounts of sediments from the seabed, which can harm some marine species and impact the food chain.

Surface trawling, as the name suggests, takes place closer to the surface of the water. While less is mentioned about this type of trawling, it is likely to share similarities with midwater and bottom trawling in terms of technique and potential advantages and disadvantages.

Trawlers can be beam trawlers, otter trawlers or pair trawlers

Trawlers are boats used for trawling, an industrial method of fishing that involves pulling a net (trawl) through the water behind one or more boats. Trawlers can be small open boats with 30 hp engines or large factory trawlers with over 10,000 hp.

Trawlers can be beam trawlers, otter trawlers, or pair trawlers. Beam trawlers use a solid metal beam, with metal plates, or 'shoes', at each end to keep the trawl net open. Beam trawling is mainly used on smaller vessels fishing for flatfish or prawns. Otter trawlers derive their name from the large rectangular otter boards used to keep the mouth of the trawl net open. Otter boards are made of timber or steel and are positioned so that the hydrodynamic forces push them outwards, keeping the net open. Otter trawling is often used for bottom trawling, where the net is towed along the seafloor.

Pair trawling is a fishing activity carried out by two boats, with one towing each warp (the towing cables). The lateral pull of the two vessels keeps the mouth of the net open, so otter boards are not required, and a larger net can be used. Pair trawling is effective for all demersal species and can result in a higher catch per vessel compared to standard bottom trawling. However, it has been controversial due to the high level of marine mammal bycatch, leading to a ban on pair trawling for bass in UK territorial waters.

Trawlers can be wet fish trawlers or freezer trawlers

Trawlers are boats used for trawling, an industrial method of fishing that involves pulling a net through the water behind one or more boats. Trawlers can be wet fish trawlers or freezer trawlers. Wet fish trawlers store fish in a fresh/wet condition, in boxes covered with ice or with ice in the fish hold. They must operate in areas close to their landing place, and the time they can spend fishing is limited. Freezer trawlers, on the other hand, have facilities for preserving fish by freezing, allowing them to stay at sea for extended periods. They are medium- to large-sized trawlers, with a similar layout to stern or side trawlers.

Wet fish trawlers keep their catch fresh by chilling them with ice or refrigerated seawater, or freezing them in blocks. They may also have some onboard fish processing capabilities, such as sorting and washing devices, or mechanical gutting and filleting. Freezer trawlers, on the other hand, can stay at sea for longer periods due to their freezing capabilities. They are typically medium- to large-sized vessels with a similar layout to stern or side trawlers.

The type of trawler used depends on various factors, including the size and power of the boat, local traditions, and bottom conditions. Trawlers can range from small open boats with 30 horsepower engines to large factory ships with over 10,000 horsepower. The gear used for trawling can also vary, including beam trawls, large-opening midwater trawls, and large bottom trawls like "rock hoppers", which are rigged with wheels to navigate rocky bottoms.

The choice between wet fish and freezer trawlers depends on the specific needs and constraints of the fishing operation. Wet fish trawlers are limited by their proximity to landing places and the freshness of their catch, while freezer trawlers offer more flexibility in terms of time spent at sea and the ability to preserve their catch for later processing.

Trawlers are sometimes confused with trollers

On the other hand, trolling is a method of fishing that involves drawing one or more fishing lines baited with lures or bait fish through the water at a consistent, low speed. This can be done behind a moving boat or by slowly winding the line in from a static position. Trolling is used for both recreational and commercial fishing, while trawling is primarily used for commercial fishing. Trawlers are generally larger vessels, with some trawlers in the ocean pollock fishery reaching up to 600 feet in length.

Another difference between the two types of fishing is the species of fish they target. Trawlers typically catch large quantities of midwater species and bottomfish, as mentioned earlier. In contrast, trolling is used to catch pelagic fish such as salmon, mackerel, and kingfish.

In terms of environmental impact, trawling has been the subject of protests by environmentalists due to its lack of selectivity and the physical damage it causes to the seabed. Trawling can stir up significant amounts of sediments and harm some marine species, as well as contribute to the creation of harmful algae blooms. On the other hand, trolling does not have the same level of environmental impact, although it can still be hazardous due to the use of downriggers that can snag on submerged objects.

While trawlers and trollers have some similarities in their names and fishing methods, they differ in their scale, target species, and environmental impacts. Trawlers are larger vessels that catch large quantities of fish using cone-shaped nets, while trollers use lines and lures to catch fish and are used for both recreational and commercial fishing.

Frequently asked questions