44 SEPTEMBER 2012 Marine invertebrates can provide a valuable substitute or supplementary nutritional source that may decrease the demand for fishmeal in the production of aquafeeds. Large-scale production of live aquatic worms and other invertebrates also may be useful for marine or estuarine stock enhancement and sea ranching efforts, as well as for aquarium, terrarium, laboratory and hobby maintenance of fishes, amphibians, reptiles, birds and larger invertebrates. Ideally a mass cultured invertebrate is fast-growing, precocious, fecund, easy to rear and able to thrive at high densities (Ivelva 1973). White worms Enchytraeus albidus are 2–4 cm long, globally distributed, intertidal oligochaetes that feed on decaying organic matter. They are found on a wide variety of moist terrestrial soils, in fresh and brackish waters, in the marine littoral zone and on aquatic plants washed ashore. They have even been found in large densities within the gravel filters of irrigated fields as well as in urban water pipes (Ivelva 1973). Their ease of culture may enable the production of a natural, sustainable feed for marine aquaculture. White Worm Productivity Experimental work on the mass culture of invertebrates for production purposes began in Russia at the end of the nineteenth century (Ivleva 1973). White or pot worm cultivation was developed in the 1940s as a result of expanding fish culture programs in the former USSR. Studies on the biology, nutrition and cultivation of white worms are reported in Russian-language publications but few have been translated into English (Vedrasco et al. 2002). Published reviews describe rooms of wall-to-wall racks stacked with wooden boxes (50 x 40 x 12 cm) of worms (100 - 300 g/box). Many fish breeding facilities maintained over 1,000 of these boxes and produced 500 kg to several tons of white worms per season to feed 2.5 to 3 million juvenile sturgeon (Ivelva 1973, Memiş et al. 2004). Peak production biomass can be 2–3 kg/m2 with mean production of 1.2 kg/m2 (Ivleva 1973). An individual white worm can produce approximately 1,000 viable eggs over the course of its lifetime (L50 = 200 d), of which 93-95 percent will develop successfully. The species has a high survival rate at all growth and developmental stages. Although some aquarium hobbyist and research organism suppliers produce white worms on a small-scale for use as feed by hobby aquarists and for biological and toxicological studies, currently no targeted, large-scale production is occurring. The reasons for this are unclear, but the cessation of production appears to correspond with the breakup of the Soviet Union and perhaps the increased availability of formulated feeds there. Worm Feeds White worms are composters and feed on decaying plant- and animal-based organic matter under natural conditions. Thus, these worms can be cultured on a variety of feeds considered wastes, including the byproducts of brewery, bakery and other food processing industries, as well as proteolyzed yeasts prepared in paper and pulp plants (Ivelva 1973). This dietary flexibility provides the culturist with the potential to develop mutually beneficial local partnerships and generate favorable publicity. The use of wastes as worm fodder keeps materials that would normally end up in a landfill within a sustainable food production system. These wastes provide the culturist with an inexpensive and easily obtained food supply for worm production. Instructions for the small-scale production of white worms to feed ornamental fish (e.g., discus, bettas, angelfish, and killifish) can be found widely on the Internet. However, mass culture is successful only in exceptional cases, with the difficulty lying in the transition from a satisfactory, modest production to an efficient, large-scale operation expected to produce hundreds or thousands of kilograms (Ivleva 1973). Culture Methods at UNH For small-scale production at the University of New Hampshire, worms were reared in clear plastic shoeboxes (34.5 x 20.25 x 12.75 cm) filled 5-7 cm high with damp organic potting soil (Walsh 2012). Feeding and moistening of the soils of all cultures (up to 25) took less than one hour, once per week. Feed, such as stale formulated fish pellets, baby cereal flakes, hot dog rolls, a mixture of moistened dry dog food with oil, was distributed against the bottom of containers and covered White Worms Enchytraeus albidus as a Live Feed and in Formulated Aquafeeds Michelle L. Walsh 1 White worms are composters and feed on decaying plant- and animal-based organic matter under natural conditions. Thus, these worms can be cultured on a variety of feeds considered wastes, including the byproducts of brewery, bakery and other food processing industries, as well as proteolyzed yeasts prepared in paper and pulp plants. This dietary flexibility provides the culturist with the potential to develop mutually beneficial local partnerships and generate favorable publicity.
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