Class Polychaeta : Bristle worms

Order Phyllodocida

Order Capitellida

Worms are the most important of bait species collected in the UK, by digging on sediment shores. Their exploitation is also completely unregulated, since they are not classified as seafish and do not fall under the scope of fisheries legislation.

This Class is the largest group of worms. All are aquatic and the great majority is marine. A few polychaetes are commensal or parasitic, but most are free-living and include pelagic swimmers, crawling and actively burrowing species, and tube-dwelling species. However, only a very small number of the over 1,000 species which occur in UK waters are sufficiently large, robust, common and easily obtained to be target bait species.

Ragworms are very common errant (free-living) polychaetes all around the British Isles. Nineteen species have been recorded on British coasts, in nine genera (Knight-Jones et al., in Hayward and Ryland 1995).

All Nereidae are semelparous (or monotelic), breeding only once in their lifecycle before dying. When male and female ragworms reach maturity, hormonal changes cause their bodies to alter. Their digestive systems break down, to enable large numbers of eggs and sperm to be produced, and most species develop large eyes and swimming legs in preparation for leaving their burrows to spawn at the water surface. A combination of a temperature cue and lunar cycle stimulates the release of pheromones and gametes from all the mature worms in the population. Spawning during spring tides probably ensures the maximum dispersion of fertilised eggs in the water column. Some cultures collect spawning, protein-rich, reef polychaete worms for food (e.g. Palolo palolo worms in Samoa, South Pacific).

Some ragworms are capable of maturing and breeding after just one year’s growth in good conditions, but most important bait species take rather longer. King ragworms Nereis virens are two or three years old before hormonal changes trigger breeding in UK populations. Usually, therefore, about one third of the population will breed every year. However a proportion of the large king ragworms in the Menai Strait population exhibit delayed maturity, with only about 20% spawning each year (Coates 1983, Olive 1987).

The omnivorous nature of ragworms, their fast growth and swift maturity, makes them very suitable for large-scale commercial bait worm farming. This has the capacity to alleviate some baitdigging pressure from sensitive intertidal areas. However, farming may also result in the accidental release of non-native species imported for use as bait, or for farming in the UK. Non-native species are increasingly being imported into mainland Europe from Korea, Taiwan and the USA to satisfy demand for bait (Olive pers. comm.). Roch et al. (1990) report on their purchase from a retail shop in Italy of a Nereis sp. from the Yellow Sea, Japan.

The following species are most commonly collected for bait on UK shores:

Hediste (Nereis) diversicolor (O F Müller, 1776). Harbour rag. A greenish, yellowish or orange worm with a prominent dorsal blood vessel some 60-120 mm long. Feeds by spinning a mucous net to catch food particles (mainly dead organic material) suspended in the water. Found burrowing in intertidal black (anoxic) muddy sand, often in brackish areas, around most British coasts, and north-west Europe as far as the Mediterranean. Neither sex leaves their burrows when spawning and larval young do not disperse very far. Feeding birds may take up to 90% of the population during the year (Mettam 1981).

Neanthes (Nereis) virens (M Sars, 1835). King rag. A large dark green worm with large leaf-like dorsal lappets giving a fringed appearance to the body. This commonly grows to 200-300 mm long, and much more in a few areas (notably the Menai Strait, where maturity is delayed in a significant proportion of large worms). The king rag occurs in a mucus-lined burrow in black muddy sand habitat on most British shores. It scavenges and can take small invertebrates with its large jaws (although these may be used mainly for defence). Male king ragworms swim out of the burrows to spawn and fertilisation of eggs takes place inside the females’ burrows. There is a brief planktonic larval stage. Large numbers of dead males are sometimes reported washed up after spawning. The king rag is a highly valued bait species, and is particularly common in the south and west and on the Atlantic coast of Europe. It is farmed for commercial bait production, but some commercial bait outlets report that farmed ragworm do not travel well and can be of poor quality.

Perinereis cultrifera (Grube, 1840). Ragworm. A bronze-green worm with bright red dorsal vessel and parapods (‘legs’), reaching 100-250 mm long. Makes galleries in mud inside rock crevices, under stones and in eel grass. Common bait species, found all around British coasts, in north-west Europe to the Mediterranean (and in the Indian Ocean).

Medium or large, smooth, silvery worms which actively swim and burrow in clean sand beaches, usually close to the low water mark. The largest specimens are used for bait and are particularly sought-after by some anglers, including match fishermen.

Catworms do not have permanent, visible, burrows but wander through the sand in search of their prey (which may include smaller conspecifics). They are long-lived and can be aged by counting the annual growth rings in their jaws. An average three-inch long worm is usually four or five years old, and the largest worms in a UK population may be up to 12 years of age (Olive 1985b). Caron et al. (1995) report on an ‘enormous’ individual of Nephtys caeca from Canada with 15 visible jaw rings.

Like the ragworms, the catworms have separate sexes and all worms in the population breed on the same day. However, catworms are iteroparous, or polytelic, and may breed several times in their lifetime. Breeding does not necessarily take place every year; sometimes the worms reabsorb their gametes before spawning can occur. Olive (1985b) recorded only two successful spawnings in one species during the ten year period from 1975 to 1985. Catworm larvae have a long planktonic phase and may not settle onto the bottom until five weeks after fertilisation. Their slow growth, infrequent spawning and low recruitment rates make Nephtys species very vulnerable to bait digging (it is possible for local populations to be dug out), and also unsuitable for bait culture.

There are about ten species in two genera (Aglaophamus and Nephtys) recorded in Britain (Knight-Jones et al., in Hayward and Ryland 1995), although Howson and Picton (1997) record a larger number in the region. The three most common intertidal species are listed below.

Nephtys caeca Fabricus. 150-250 mm long, common and widespread in the intertidal and at low water all around Britain, and in the Arctic and Northeast Atlantic. Caron et al. (1995) report on an individual (>23g) of Nephtys caeca sampled in Canada that was over 23 g in weight and 15 years old, in a population with a longevity of over 6 years.

Nephtys cirrosa Ehlers. 60-100 mm long, found in the intertidal and at low water mark all around Britain and on the Atlantic coast of Europe.

Nephtys hombergi Savigny. 100-200 mm long, common and widespread in the intertidal and at low water all around Britain, north-west Europe and the Mediterranean.

The lugworms are the most popular bait worm used by anglers in the UK, and are extremely common. They are collected extensively by anglers for their own use, and by commercial diggers for resale. Two species are commonly used for bait (see below), but since one of these was only described relatively recently, differences in their ecology and life cycles are still not fully understood.

Lugworms live in U or J-shaped burrows on sandy and muddy sand shores, and feed on the remains of decaying seaweed, diatoms and bacteria. They are also found in the sublittoral, in muddy sands and mud, and may be particularly common around sources of organic input (e.g. fish farms). The location of lugworm burrows is obvious from the spiralled faecal sand casts left on the surface above one entrance to the burrow.

Lugworms begin to breed at an age of two years, when they also reach a large enough size to be considered suitable as bait. Each animal spawns on a single day, and the entire population of any beach completes spawning within a few days, although populations on different beaches spawn at different times. Most lugworms breed in winter (October to March), with the majority spawning in November and December. Some 20% of lugworms spawn in summer (July to September, Shahid 1982). Some lugworms die after spawning, and the remainder stops feeding and producing sandcasts for the period during which their larvae are living attached to sand grains in the adult burrows. Adult populations are at their lowest density, and individual worms at their smallest size in winter after breeding. Population density and worm size both increase quickly in spring as growth rates rise and maturing worms migrate into the adult lugworm beds.

Soon after fertilisation, the larvae migrate from the adult beds to a zone just below the low water mark, where they occur in dense populations for the next six months until they reach a length of about 10 mm. They then swim in a mucus tube to the upper part of the shore, where plenty of organic material occurs in a zone just below the strand line (in natural conditions; beach cleaning operations will remove much of the organic input usually provided during the holiday season). Very dense beds of juvenile lugworms occur in this area. The maturing worms eventually move down to the less densely populated adult beds at the bottom of the shore and in the sublittoral. Adult worms are capable of living for six years. They reach weights of 25 g in the south and west, or 10 g in the north-east, and may breed several times during their lifetime.

This complex life cycle makes lugworms very resilient to bait collection pressure, provided that bait diggers do not dig in the nursery beds high on the shore. Populations on the lowest part of the shore and in the shallow sublittoral are only rarely or never exploited. Adult worms will migrate into dug areas from these refuge populations, as well as from the nursery beds. However, the same complexity of life cycle and their relatively slow growth makes lugworms difficult candidates for bait farming, although progress is now being made with the culture of UK species (Olive pers. comm.).

Three genera are reported by Howson and Picton (1997) to occur in and around UK waters: Arenicola (two species), Arenicolides (three species), and Branchiomaldane (one species). Bait collectors actively target the two species of Arenicola. The two more common Arenicolides species (A. branchialis and A. ecaudata) are found in mixed sediments among rocks and stones, which are less likely to be dug over by most lugworm collectors (although they will be encountered in this habitat by ragworm collectors).

Other species of Arenicolidae are apparently used for human consumption as well as for fishing bait in East Asia. Trade statistics, based on custom clearance statistics released by the Japanese Ministry of Finance, record that 1,119 MT of lugworms and sea lavenders (living), worth 710 million yen, were exported from Japan to Korea in 1997. (Data from March issue of East Asia Economic Information, published by Tokyo-based East Asia Trade Research Board.) Other sources record that some of these lugworms are processed and canned in tomato sauce, presumably for human consumption.

Arenicola marina (Linnaeus). Blow lug (also known as lobworm and yellowtail). This species occupies U-shaped burrows, marked by a faecal cast and a feeding depression, on the lower shore of clean to muddy sand beaches. Its range extends from the Arctic to the Mediterranean in Northwest Europe. At 150-200 mm long, this is one of the most important UK fishing bait species, dug by hand. The blow lug is sold commercially for bait in many regions, but as a relatively small worm, it is less sought-after than black lug.

Arenicola defodiens Cadman and Nelson-Smith, 1993. Black lug (or runnydown). A larger worm than A. marina, and therefore particularly sought after by bait collectors (commercially and for personal use). This species occurs in a lower zone of the intertidal, and possibly on more exposed beaches, in J-shaped burrows marked by a faecal cast characterised by a hole in the centre of the cast (Mr Sharp pers. comm.). It is therefore mainly obtainable during low water spring tides, and is usually collected using a bait pump. It has only recently been distinguished from A. marina, and full details of its geographic distribution and life cycle are not yet available. Bait diggers report that the species seems to prefer areas that are relatively enriched, either by local sewage outfalls or exposed shores in estuaries (Mr Sharp pers. comm.). Black lug collected for resale are usually gutted and wrapped in newspaper.

Marphysa sanguinea (Montagu). Verm. Broad flattened body of 300 or more segments and 300-600 mm long. Valued as angling bait in the Channel Islands, but can bite painfully when handled. Found in mucus-lined galleries in muddy sand under stones and among old shells on the lower shore on western coasts of Britain.

Other species of Marphysa enter the international trade in bait worms (particularly to the Mediterranean) and their introduction to areas where they do not occur naturally could be environmentally damaging (Peter Olive pers. comm.).

Some 16 species in four genera are recorded in the UK, some of which can deliver a painful bite (said to resemble a bee sting). None of these UK species are known to be used for bait, but this family is introduced here because of the extensive international trade in Glycera dibrachiata, a species from the Northwest Atlantic which is imported to Europe (Atlantic and Mediterranean coasts) and elsewhere (see Section 6.7 below). This species has large jaws with a poison gland, and would be an extremely unwelcome addition to the European marine fauna.

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