Pots and Traps - General
- Inkwell pots
- Crab pots
- Prawn creels
Pots and traps are generally rigid structures into which fish or shellfish are guided or enticed through funnels that make entry easy but from which escape is difficult. There are many different styles and designs, each one has been designed to suit the behaviour of its target species. Many designs have evolved over many years to suit the coastline and seabed where it is used only changing to make use of modern materials.
Most pots and traps should have low environmental impact and seabed impact.
In certain circumstances there may well be instances of Ghost fishing of lost pots and traps but this can be minimised by using appropriate gear and release devices. One of the main causes of gear losses is the interaction of mobile gear with static gear. Nowadays the instances of this should be fewer due to the improvements in communication between different commercial fishing sectors and the ability to accurately monitor gear placement using GPS systems.
By-catch is minimal and usually confined to small animals of the target species. This can be minimised by the use of appropriate mesh sizes in the cover netting and the use of relevant escape gaps. Any by-catch in the pots can be easily removed from the trap and released back into the sea immediately without harm.
Seabed impact with pots and traps is limited to light contact of the traps and minimal penetration of the seabed from the small anchors or weights that are used at the ends of the fleets of some gears. There may be some movement of the gear and the ropes on the seabed particularly in poor weather but this will not have much effect on the seabed.
Traps, in various forms of cages or baskets, have been used throughout the world for thousands of years to catch a wide variety of fish and shellfish. The basic design has not changed much over the years; the major changes have been in the materials that are used to make the gear. Early gear would have been made with wicker or willow, woven into a basket-form with a tapered entrance in the top, and stones inside to weight them down on the seabed. Nowadays, the pots and traps are made, along similar lines to the old wicker ones, but using modern materials such as wood, steel, plastic, etc. for the frame; this being covered with nylon and polyethylene netting.
Modern pots and traps tend to differ in shape, size and construction materials according to the behaviour of the target species, and local fishing practices. However, they will all be similar in that they will have at least one tapered entrance that makes it easy for the shellfish to enter, but very difficult for them to find their way out again. There is a big variation in the names of the different traps in different fisheries, with them being referred to most commonly as pots, creels, traps — but there will be numerous different local names for the different styles of pot. The pots are baited, usually with some type of fish. As with the pot construction, the choice of bait varies greatly with the locality and the target species, with some baits proving much more suitable for certain species than others. Despite this, it often comes down to what type of bait is readily available, and at a reasonable price.
The traps can either by shot individually or more commonly in strings (fleets), where a number of pots are attached to one long rope and laid on the seabed, with a dhan or bouy to mark the location of each end of the fleet. If the pots are very light weight, as in Nephrops creels, an anchor or weight may be added at both ends of the fleet.
The number of pots in a fleet depends on many factors, such as the type of pot used, the target species, the size and design of vessel, the area they are shot in, the type of seabed, and the personal preference of the skipper and crew.
The numbers in a fleet can vary from five in some inshore lobster fisheries to over 100 in offshore crab fisheries and Nephrops fisheries. The pots are baited and shot away from the vessel as it steams slowly ahead and, are left on the seabed to fish for a period of, usually, 24 hours. If left much more than overnight, there can be a tendency for some of the shellfish that are already in the traps to escape, thereby creating a loss of revenue for the vessel. The pots are hauled by firstly picking up the dhan at the end of the fleet of pots and leading the rope to the creel hauler. The hauler is usually mounted forward, to one side of the vessel. As the pots are hauled up to the vessel, the creel hauler will be slowed down as the pots approach the vessel side. They will then be hauled, or manhandled, over the side of the vessel and onto a flat working table where the catch is removed and placed in a container for onboard sorting and processing before storage. As the catch is being taken out of the trap, any by-catch or undersized crabs and lobster will be immediately returned to the sea and the traps will be re-baited. The re-baited pots are passed across the deck and stowed in correct order so that they are all ready to be shot away again. In the meantime, the hauler will have been engaged again to haul in the rope until the next pot is at the side of the vessel, and the whole process is repeated and continues like this until the whole fleet is onboard the vessel. The skipper will manoeuvre the vessel into position and start to shoot the fleet again. This is usually done by shooting away the dhan and rope and probably manhandling the first trap into the water. After this, the rest of the fleet should be ‘towed of the stern of the boat in turn as each length of rope comes tight. However, if there has not been a good catch the skipper may opt to keep the fleet onboard and move fishing grounds a short way in an attempt to improve the next day’s catch. This routine and layout is fairly standard on all UK vessels, and many overseas vessels fishing with traps and pots.
All sizes of vessels can fish with traps, with small inshore open boats often operating with a few traps shot individually instead of in fleets and hauled by hand, right up to 20 – 30 metre vessels operating several thousand pots in fleets of around 100. The smaller vessels will store their catch in boxes and land them daily, or put them into storage cages left underwater until the shellfish buyer is in port to collect them. The larger vessels will store their catch in vivier tanks to keep them alive onboard the vessel and land their catch after several days of fishing. A vivier tank is a tank built into the hull of the vessel with a pump system to circulate fresh seawater to keep the animals alive. Once put ashore, many shellfish buyers will transport the catch in lorries fitted with vivier tanks to ensure the shellfish are still alive and fresh when they reach the end user.
Shellfish can be transported long distances in this way, with much of the UK catch being shipped to France and Spain while it is still alive.
Traps and pots, of some description, are used all around the shores of the UK with fishermen concentrating on species such as crabs, lobsters, crayfish, Nephrops, whelks, spider crabs, velvet crabs, cuttlefish and several other species but in lesser numbers. The gear will be designed taking into consideration the behaviour of target species and fished on grounds where they are known to frequent. This helps to make pots and traps very efficient in species selectivity. However, in some cases there may be a small by-catch of other shellfish. Almost all of this will be retained and sold, with any undersize or unwanted.
A Pilot Pot Fishery for Nephrops Norvegicus off the Northern Ireland coast
The Evaluation of Ghost Fishing Preventors for Shellfish Traps
Main target species (UK)
- Brown Crab
- Spider Crabs
- Velvet Crab
- Very little bycatch