ICES Marine Science Symposia, 215: 416—423. 2002 The potential for ranching the scallop, Pecten maximus - past, present and future: problems and opportunities

Dan Minchin

Minchin, D. 2002. The potential for ranching the scallop, Pecten maximus - past, pres­ ent, and future: problems and opportunities. - ICES Marine Science Symposia, 215: 416-423.

Ranching scallops requires a full knowledge of their biology, and this has only evolved during the last half-century. This knowledge needed to be merged with the technolog­ ical developments of plastics, improved power, improved navigation, and aided by legal implements. Scallop cultivation in hatcheries has greatly contributed to produc­ tivity of spat used as a source for several ranching programmes. Depletion of natural scallop populations has made it necessary to consider ranching as a means for creat­ ing a sustained resource. Few areas currently have sufficient natural settlements; when these occur, they vary in intensity from year to year. As a result, collections of wild spat cannot provide a consistent source of supply. Movements of spat may need to be controlled to maintain the diversity present in some isolated populations and to reduce disease, disease agents, and parasite transfers. Future opportunities exist for ranching scallops provided there is an improved knowledge of their interactions with other biota. Developments in biotechnology and reduced predation rates are likely to lead to significant increases in production. Flowever, the spread in the range of toxic algal events and exotic species could modify such expectations.

Keywords: biology, culture, ranching, scallops.

Dan Minchin: Marine Organism Investigations, 3, Marina Village, Ballina, Killaloe, Co. Clare, Ireland; tel: +35J 86 60 80 888: e-mail: [email protected].

Introduction development was advanced by the endeavours of those who frequently reported their findings to ICES Statu­ The discipline of ranching scallops in Europe has tory Meetings. In addition, knowledge gleaned for other evolved during the last 25 years following high exploita­ scallop species worldwide was avidly assimilated and tion levels and population declines. The possibility of used in attempts to develop a viable ranching industry. restocking using releases of scallops was inspired by the development of an industry in Japan based on cultivat­ ing the scallop Patinopecten yessoensis (Ventilla, 1982; Exploitation Aoyama, 1989). However, in order to get to this stage, a greatly improved knowledge of scallop biology and han­ The scallop has long been regarded as an item of beau­ dling skills was needed. The information that led to the ty on account of its unique shape and has been the sub­ first attempts to cultivate Pecten maximus relied on the ject of artistic impression for many centuries (Cox, basic biological information gained from the 1940s. 1957). Its shell has been used for vessels and containers Nevertheless, more information is still needed in order for thousands of years and over the last century has to improve growth and survival and increase recapture become one of the more highly prized of seafoods, lead­ rates. This account examines the development of ranch­ ing to its high level of exploitation. ing, with particular reference to what has happened in In Ireland, some of the earliest records date from Ireland. The range for Pecten maximus extends from about 5470 BC (F. Mitchell, pers. comm.) from shell northern Norway to the west coast of Africa (Mason, middens. Shells have also been found elsewhere in un­ 1983a) and possibly into the Mediterranean Sea, as dated cave sites (Jackson, 1934). There is some indica­ Pecten jacobeus may be a form of Pecten maximus. The tion that scallops may have been commercially fished countries principally involved in investigations have during the 16th century in Ireland (Stanley, 1967) and been Spain, France, the United Kingdom, Norway, and were captured on the west coast of Ireland in the mid-to- Ireland, all ICES Member Countries. Although ICES late 1600s, but not in sufficient abundance to form a had not evolved a specific programme for the ranching trade, according to an Inquiry Report of 1836. Andrews of P. maximus, much of the information enabling this (1847) reported that small boats took scallops on the The potential for ranching the scallop, Pecten maximus - past, present, and future: problems and opportunities 417 southwest coast, and Brabazon ( 1848) records the use of tury before, the idea of managing scallop stocks by en­ oyster dredges for catching scallops. These scallops hancement seemed practical. were caught and used for soup, but more especially they were important for baiting longlines; the curved gonad is well shaped for placement on a hook. At about this Understanding the biology same time, there was a small fishery in Strangford Lough which included boats from Jersey (Welch, 1934). There were unexplained changes in scallop seasonal One method, probably used over a long period of abundance together with alleged sightings of swimming time, was the taking of scallops on calm days using a scallops that led to the belief that they migrated. This hoop net on a long pole into which the scallop was hypothesis was explored by Gibson (1953); he studied tipped (Gibson, 1957). Storms have washed scallops the movements of tagged scallops and, following diving ashore on beaches, and such events still continue to take investigations with Baird (Baird and Gibson, 1956), place from time to time. Oyster dredges were used for suggested that scallops "migrate" from "feeder beds" - their capture, but with the addition of a toothed bar, areas where young scallops accumulated following set­ scallops could be more efficiently raked from the sedi­ tlement. Their contentions were, in fact, partly correct. ment. Boats either used sail for power or hand-winched Thirty-five years later, in the same bay, scallop spat a 50-fathom anchor line using a capstan while dragging were found to gradually disperse to the large expanse of the dredge (Gibson, 1957). From the 1920s, captured sediment, where adult scallops were found, after detach­ scallops were dispatched in jute sacks to the Billings­ ment from marine algae (Minchin, 1992a). The move­ gate market in London. This was attributable to the main ments that followed after byssal release could not be demand being outside the country and the lack of home- considered as a migration because there was no obvious processing facilities at that time. Production rose during actively directed movement. Current and wave wash the period of general food scarcity in England during most probably dispersed scallops to the more open and 1940-1949 (Gibson, 1956). With the development of dredged ground. Baird and Gibson also noted that freezing and processing facilities and increased storage younger scallops were poorly represented in dredge capacity, exploitation in Ireland increased from the hauls, but Baird was able to recover a greater proportion 1960s. The use of outboard motors and then the more of younger scallops when diving on the same grounds powerful inboard motors led to increases in catching (Baird and Gibson, 1956). From these investigations, it ability. In the 1950s, Dick Baird designed a dredge with was realized that the tooth spacing on the bar used to a diving plane to prevent the dredge from hopping on rake the scallops out of the bottom was the important the seabed (Baird, 1959; Rolfe, 1969) and over two measurement for the selection of adult scallops rather decades, a wide range of dredge designs ensued. The than the mesh size of the bag. shallow inshore beds were the first to be exploited. Some years later, scallops were found to move up the Further increases in power resulted in a greater number slope of large ponds and concentrate near the water sur­ of dredges being used to fish progressively deeper face. In the still water environment of a pond, the vec­ waters. The dredges were designed to fish a wide range tors of tidal current and wave surge could not override of substrates by having spring-loaded teeth that would any specific small-distance movements of scallops. It is not snag on boulders. Scallops collected in this way interesting to note that concentrations of scallops occur were often broken. close to the base of scree slopes in fjords. These move­ Pulses of landings followed the finding of previously ments may, in fact, be a migration up-slope to better unexploited beds (Mason, 1983a). Following a series of feeding conditions or to form concentrations so as to coastal surveys along the Irish coast, several new fish- maximize fertilization (Minchin, 1987). able beds were found (Lee, 1973a, 1973b). Improve­ Growth rings appearing on the flat shell were used to ments in fishing efficiency and in dredge design togeth­ age scallops (Mason, 1957). The reproduction cycle was er with vessel modernization eventually resulted in extrapolated from changes in the size, shape, and colour reduced stock numbers and the necessity for conserva­ of the gonads, verified by histological techniques (Ma­ tion. Legislation varied in each country owing to the son, 1958), and enabled calculations of natural mortali­ varying rates of growth and social circumstances. In ty of unexploited populations (Gruffydd, 1974a). The Ireland, a by-law prevented the more efficient means of identity of larval scallops in plankton samples was made procuring shellfish by diving. Some heavily exploited possible following the studies by Rees (1950). He had fisheries in France became dependent on a small num­ examined the morphology of bivalve larvae in the North ber of year classes, and there were concerns for the Sea, but more detailed studies of larvae were to follow future of the fishery following a period of poor recruit­ (Le Pennec, 1974), and the time at which they settled ment (Ansell et al., 1991). Reliance on continued ex­ could be predicted by following their growth in the pansion of the industry based on previously unfished plankton. This helped in timing the deployment of col­ populations was unjustified, and existing stocks were lectors, thus increasing yields and reducing fouling. subject to high fishing pressure. As with the measures to For a very long time, the existence of scallops to cultivate oysters following their depletion almost a cen­ thumbnail size was rarely observed. The earliest record- 418 D. Minchin ed small scallops were those found by the Reverend ther (Minchin, 1993). The occasional success obtained Barlee, a Church of Ireland clergyman, in 1845. He col­ through rearing larvae to settlement in mesocosms lected large numbers of small Pecten maximus from immersed in the sea (G. Burnell, pers. comm.) or in Bertrabouy Bay on the west coast of Ireland, and these silos on land (Anderson et a l, 2000) may result in samples were recently rediscovered in the Smithsonian cheaper spat production once techniques are perfected. Museum. USA (Dr Thomas Waller, pers. comm). A cen­ Advances in feeding recently settled scallops in nursery tury later, Elmhurst (1945) described the finding of culture have also reduced costs (Rodhouse et al., 1981). some small spat, followed by collections of spat by Eg­ Reports of scallop spat collections in the wild for dif­ gleston (1962). The diving pioneer Jack Kitching found ferent countries were based on activities mainly in the many spat attached to hydroids and marine algae 1970s in France (Buestel, 1976; Buestel et al., 1979), (Kitching and Ebling, 1967) while working in Lough Ireland (Minchin, 1976), Scotland (Ventilla, 1977; Fra­ Hyne, Ireland. Mason (1969) then collected spat in zer and Mason, 1987), England (Pickett, 1978), Isle of localized areas where scallops had concentrated on the Man (Brand et al., 1980), and Spain (Roman et al., west coast of Scotland. Here, scallops grew and de­ 1985), although recruitment was found to be quite vari­ tached and, where there were few currents, would accu­ able (Boucher, 1985). Spat were obtained using differ­ mulate on the sediment nearby. In strong current areas, ent collector designs ranging from onion bags holding they were probably widely dispersed at a smaller size, small sections of confiscated drift salmon netting to their byssus not being strong enough to retain them; cur­ "humbug" collectors made up of stiff tetrahedra of plas­ rents easily disperse the light spat. This could explain tic containing net fillers. It was clear that many of these why they were rarely found in the strong tidal regions studies would not have advanced, but for the develop­ off the coasts of the Isle of Man and Brittany (Minchin, ment of plastic products used in pearl nets, lantern nets, 1992a). trays, cages, and synthetic rope. Some of the plastics Gibson (1956, 1959) noted that there were two main used were originally designed for other purposes, such settlements on the west and southwest coasts of Ireland, as the dishwasher tray later to become the well-known and this, he claimed, explained the two modes of the NW Plastic trays, used extensively in shellfish culture first year’s winter growth rings found in these popula­ during the 1980s and 1990s. tions. This first growth ring is not easily deciphered Environmental factors were also of importance in the from shell markings, and it now appears that the two management of stock (Gruffydd, 1974b; Wilson, 1987). growth rings may now represent two different year The layout of longlines tested and used in cultivation in classes (Minchin, 1992a). The modes from the two main Japan was employed. Although the efficiency of handling periods of settlement in a given year tend to merge, scallops gradually improved, the predation on scallops owing to variable growth rates and selective predation, and fouling of collectors and trays persisted. Some solu­ to give a single prominent mode. Most of the errors in tions to these problems, for example, the mortalities the ageing of populations stem from this early assump­ resulting from the binding of scallops with the byssal tion. threads from mussels, could be considerably reduced by introducing dogwhelks (Nucella lapillus) to the trays (Minchin, 1989). Culture of scallops A substance recommended in the early 1980s for con­ trolling fouling on shellfish cages was tributyltin. This Through knowing the reproductive cycle of scallops, it is highly toxic and impaired shellfish broodstock. It was was possible to spawn them in the laboratory (Comely, also used on fish cages, and this almost certainly led to 1972; Sasaki, 1979; Gruffydd and Beaumont, 1972; the poor and failed settlements of scallops in Mulroy Buestel et al., 1982). Settlements were obtained, often Bay, Ireland (Minchin et a l, 1987). In addition, its with difficulty because of varying egg quality (Cochard, usage by ships as an antifoulant on hulls may have led 1987), in part determined by their lipid content (Paulet, to declines of scallop stocks in enclosed harbours such 1989). With further knowledge of broodstock manage­ as Cork Harbour and the Rade de Brest. Legislation ment, it was possible to control reproductive activity banned its use on craft < 25 m from 1982, and this ac­ (Lubet et al., 1987), and more predictable settlements tion resulted in improvements in water quality. became possible by using correct sperm concentrations (Gruffydd and Beaumont, 1970). The production of scal­ lop spat over a long season enabled production of large Ranching numbers on which to develop an industry. For some laboratories, there has been a high depend­ Early studies in the 1970s in Ireland and France consist­ ence on antibiotics, which may reflect the geographical ed of broadcasting hundreds to thousands of scallops. It variations of water quality. Attempts at producing chea­ was a concern that the sowing of such small numbers per spat by spawning scallops in situ in sea loughs have would create a situation whereby there would be a dis­ been made; the fate of the produced embryos is proportionate mortality from immigrating predators. unknown (Minchin, 1992b), but could be explored fur­ Large-scale programmes were favoured. Survival esti­ The potential for ranching the scallop, Pecten maximus - past, present, and future: problems and opportunities 419 mates could be made from the commercial returns, but mortalities may subsequently be high. Scallops held out obtaining an indication of the survival before this time of water for periods exceeding 3 h at > 12°C show a was difficult because only small areas could be sur­ noticeable reduction in vitality (Minchin et al., 2000). veyed by diving, often with poor underwater visibility and with poor sea states. The main studies were under­ taken in the Rade de Brest and in the Baie de St Brieuc, Pandora’s sea chest France (Buestel et al., 1987; Dao, 1990) and more recently in Norwegian fjords (Strand, pers. comm). Exotic species continue to expand their ranges because Following sowing, scallops would take about two fur­ of the opportunities of free trade, introductions of "new" ther years to reach market size. The regions chosen for culture species, importation of shellfish, ballast water sowing should take account of the natural growth of releases, and hull fouling (Carlton, 1987; Carlton and scallops in these areas (Minchin and Ni Donnachada, Geller, 1993). These are the most prominent vectors, but 1995) and if transplanted, gonadal development may many others exist. These seemingly innocent activities, follow a different pattern (Latrouite and Claude, 1979), when undertaken without controls, can lead to the ex­ probably reflecting differences in the genetics of differ­ pansion of undesirable species belonging to a wide ent populations. In several experiments, unauthorized range of taxa. It is not always possible to predict their removal of scallops may have contributed unduly to pes­ harmful effects once introduced to a new geographic simistic estimates of survival. region; many are benign, and their establishment may Mortalities were associated with all ranching experi­ go unnoticed. However, some are likely to modify pro­ ments, and different bays appeared to have different duction and sales of scallops. The recent appearances of predatory problems (Paul et al., 1987) which changed amnesic shellfish poisoning (ASP) on the west coasts of with time. In the Baie de Saint Brieuc prior to the Scotland and Ireland are of grave concern, and further extended frosty period in 1963, the octopus was an im­ toxins continue to be described in cultivated shellfish. portant predator of scallops (Dao, pers. comm.), but The naked dinoflagellate Gyrodinium aureolum has since that time, the hermit crab has become more impor­ been associated with purges of bivalve larvae from the tant. In shallow inlets, scallops may also be killed by plankton and possible mortalities of spat (Minchin, extended cold periods (Minchin, 1985a). Scallops ex­ 1985b). The ICES Code of Practice (ICES, 1994) covers posed to temperatures below 4°C become torpid and those areas where species may be introduced in trade or will eventually expire. Over the last century, the biota as exotic species for culture. The advice provided in this within many European inlets may have changed consid­ Code arose over the course of 25 years, and this Code erably. The great reduction of predation by the exploita­ is also of interest to managers in countries outside tion of skates and rays may have resulted in increases in the ICES community. Controls for the management of their natural prey, such as crabs, which are known to be exotics by shipping are, in part, dealt with by Inter­ avid predators of sown scallops. Dispersal from the fish- national Maritime Organization guidelines. Unfortu­ able area also has implications for the economic viabil­ nately, these guidelines are not sufficient, and control or ity of ranching (Howell and Frazer, 1984). sterilization methods for the management of ballast Two approaches to the management of crabs have water need to be urgently examined. Many introductions been undertaken. One involves the optimum foraging have also been attributed to ships’ hull fouling. theory of Hughes (1980), whereby the crabs select scal­ Measures to control the usage of TBT antifouling paints lops and test their strength before investing any energy are likely to be implemented, with a possible banning of in opening them. The other method examines the maxi­ its use within the decade. The efficacy of alternative mum size of scallop preyed upon by crabs of different antifoulant methods, however, must be at least as effec­ sizes (Minchin, 1991). This last approach enables a cal­ tive as that of TBT. The improved management in the culation of a sowing size based on the sizes of crabs control of toxic discharges into port areas by industry trapped in the area to be sown. Still, it has been a puzzle will almost certainly make these areas more suitable for as to why crab predation has been so devastating; shell the invasion of exotic species releases in ballast water or strength of cultivated scallops, however, does seem to be for the progeny arising from brood releases or spawning much less than that of wild ones. Sometimes the shell of of hull-attached biota. the cultivated scallops has only half the strength of the wild ones (G. Haugum, unpublished). In most sowing studies, it was noticed that there was The scientific community an initial high mortality of scallops. Gradually, it be­ came apparent that the condition of scallops at the time The early studies by the pioneers Mason, Gibson, and of sowing was important; their vitality appeared to be Baird undoubtedly provided the basic information used reduced with prolonged exposure to air. Moving scal­ in the management of scallop populations today. Apart lops to the sowing area from the region in which they from the technological developments that aided these have been in intermediate cultivation involves some ex­ advances, the most important arose from the remarkable posure to air. Should this be prolonged, i.e. >12 hours. good will and open discussion of fellow scientists. The 420 D. Minchin

Table 1. Advantages and disadvantages of scallop ranching.

Disadvantages

Large mortalities due to cold winter events (1754, 1947, 1963) TBT contamination in some inshore bays ( 1980s) Poaching from divers and fishermen (from 1980s) Development of other culture activities (from 1970s) Apparent spread of algal toxins (from 1970s?)

Factors that promote cultivation in Northern Europe

Efficient recapture methods and decline of stocks (from 1950s) Development of durable plastic products (culture systems, rope, packaging) (from 1960s) Processing facilities close to production regions (from 1960s) Development of safe diving practices (from 1960s) Improved understanding of scallop biology (from 1950s) Large expanses in navigation zones in port areas available for cultivation The success of Japanese, New Zealand, Chilean, and Chinese culture-based productions

What has yet to be achieved

Successful returns from scallop ranching Development of ranching that promotes enhancement Improved understanding of predator-prey interactions Improved understanding of dispersal mechanisms Identification of optimal sowing regions Understanding of gigantism Legislation to enable private ownership Rapid assessment of scallop quality

teams of Baird and Gibson (1950s), Mason and wegian colleagues using the research facilities in Drinkwater ( 1960-1970s), Buestel and Dao (1970s), Norway. Experience gained on scallops from all areas of and Gruffydd and Beaumont (1970s) are examples of the globe was deemed to be of interest, and this infec­ how the expertise evolved and the centres of excellence tious enthusiasm still persists. The success of the large- in scallop studies developed, notably in Brest, Aberdeen. scale production and ranching of the ecomorphological- Port Erin, Menai Bridge and Conwy, La Coruna, ly similar Pecten novaezelandiae in Golden Bay, New Dublin, and more recently in Bergen. Exchanges of Zealand, demonstrated that ranching scallops with a ideas became more frequent with the Scallop (Pectinid) recessing habit could be achieved (Bull, 1987). Workshops that first met in Baltimore, Ireland, in 1976; the 11th gathering took place in Bergen in 1999. Meet­ ings normally took place every two years and represent­ Future developments ed all matters relating to scallops from science to mar­ keting. Many of the presentations from these workshops To date, ranching of Pecten maximus has met with more have been published, and reports of some of these meet­ failures than successes. Nevertheless, these experiments ings were presented to ICES (Minchin, 1976; Ma-son, have provided new information with which to improve 1983b; Beaumont and Mason, 1987). The ICES our knowledge, a summary account of which appears in Working Group on Assessment of Scallop Stocks held Table 1. One of the issues appears to be spat quality, in 1979 (ICES, 1979) contributed to the overall knowl­ which may explain the great variation in the ensuing edge, as have the many aquaculture symposia and ICES mortalities that follow a sowing. The impact of long­ Statutory Meetings via the Shellfish Committee. In the term stresses on scallops requires investigation and may 1990s, the European Union sponsored a programme to be a further quality variable that will need to be taken learn more about scallop ranching, and it clearly point­ into account, as will stocking densities and water flow ed out the difficulties with scallop spat quality and pre­ through different cage designs. There are some strong dation that required further attention (Fleury et al., behavioural responses in scallops, and some are remark­ 1997). Some of these matters were examined in a fur­ able. For example, cultured scallops once sown, recess ther EU programme run by Norway under the Large at similar rates to wild scallops. This may indeed be for­ Scale Facility, a programme that supported leading tunate because should they not do so, survival rates may researchers from elsewhere in Europe to work with Nor­ be poor. Scallop-predator interactions require further The potential for ranching the scallop, Pecten maximus - past, present, and future: problems and opportunities 421

detailed study, and these may include some unexpected laris and C. (Chlamys) varia. In Scallops: Biology, Ecology species such as sea anemones (Minchin, 1983), small and Aquaculture. Developments in Aquaculture and Fish­ spider crabs, and gobies (P.-G. Fleury, pers. comm.). eries Science, 21: 715-751. Ed. by Sandra E. Shumway. Elsevier, Amsterdam. 1095 pp. The biology of some predators remains poorly known; Aoyama, S. 1989. The Mutsu Bay scallop fisheries: scallop for example, little is known about the sea star (Mar- culture, stock enhancement and resource management. thasterias glacialis), an important scallop predator. In Marine Invertebrate Fisheries: Their Assessment and Continued investigations on various crab species are Management, pp. 525-539. Ed. by John F. Caddy. John needed to complete our understanding of their impact Wiley and Sons, New York. 752 pp. on sown scallops, as there are likely to be diurnal and Baird, R. H. 1959. Factors affecting the efficiency of dredges. In Modem Fishing Gear of the World, pp. 222-224. Ed. by seasonal variations in predation intensity. H. Kristjonsson. Fishing News (Books) Ltd., London. 607 pp. With the development of more efficient dredges, a Baird, R. H., and Gibson, F. A. 1956. Underwater observations decline in stocks has taken place, and the spatial pat­ on escallop (Pecten maximus) beds. Journal of the Marine terns of scallops have obviously been changed. The poor Biological Association of the United Kingdom, 46: 33—47. and reduced recruitment in many populations may arise Beaumont, A. R., and Mason, J. (Eds.). 1987. The Sixth from an increase in nearest neighbour distances, and so International Pectinid Workshop, Meani Bridge, Wales, 9-14 April 1987. ICES CM 1987/K:3. 31 pp. a reduced fertilization ability with fewer embryos being Boucher, J. 1985. Caractéristiques dynamiques du cycle vital produced. Should sowing of scallops include, as an de la coquille Saint-Jacques (Pecten maximus): hypothèses objective, an enhancement of settlement, there may be sur les stades critiques pour le recrutement [Dynamical less dependence on sowing activities in future years. characteristics of the life cycle of the scallop (Pecten max­ With the increase in dredge efficiency would come a imus)-. Hypotheses on the critical stages for recruitment], better recovery rate for sown scallops, and high recovery ICES CM 1985/K:23. 11 pp. Brabazon, W. 1848. Deep Sea and Coast Fisheries of Ireland. rates would make ranching projects more profitable James McGlashon, Dublin. 112 pp. because of higher returns. The sowing of scallops could Brand, A. R., Paul, J. D., and Hoogesteger, J. N. 1980. Spat set­ also lead to recreational fisheries for snorkellers, where­ tlement of the scallops Chlamys opercularis (L.) and Pecten by sown scallops released by a local community in maximus (L.) on artificial collectors. Journal of the Marine selected areas may promote tourism and increase bed Biological Association of the United Kingdom, 60: 379- nights. In the shallower waters, it may be more efficient 390. Buestel, D. 1976. A method of determination of settlement of to consider commercial harvesting using divers as there pectinidae spat. Results from the Bay of Saint Brieuc in would be less damage to the sea floor. Perhaps changes 1975. Scallop Workshop, Baltimore, Ireland, 11-16 May in licensing could promote the possibilities of ranching 1976. 8 pp. in the future, enabling divers where this is presently pro­ Buestel, D., Cochard, J. C., Dao, J.-C., and Gerard, A. 1982. hibited and enabling usage of the seabed by promoting Production artificielle de naissain des coquilles Saint- private and cooperative leasing of the seabed. Jacques Pecten maximus L. Premiers résultats en Rade de Brest (Artificial production of spat of scallop Pecten maximus, With improved understanding of the requirements of first results from the Rade de Brest). Vie Marine, 4: 24-28. scallops, a satisfactory and economic return will be real­ Buestel, D., Dao, J.-C., and Lemarie, G. 1979. The collection ized. Reduced mortality and improved production could of scallop spat in Brittany. Rapports et Procès-Verbaux des be achieved by farming scallops that exhibit gigantism; Réunions du Conseil International pour l’Exploration de la such individuals do naturally occur and may attain a Mer, 175: 80-84. weight of about 1 kg (Minchin, 1994). Buestel, D., Gerard, A., and Guenole, A. 1987. Croissance de différents lots de coquille Saint-Jacques Pecten maximus en With improved knowledge of local water movements culture sur le fond dans la Rade de Brest (Growth of différ­ and stock identities, the management of scallop popula­ ent groups of scallop Pecten maximus cultured on the bot­ tions will be further improved. Forecasting of settle­ tom in the Rade de Brest). Haliotis, 16: 463-477. ments may become possible, and the sowing of scallops Bull, M. 1987. Scallop seeding trails in New Zealand. In 6th in specific regions within certain bays may promote the International Pectinid Workshop. Ed. by A. R. Beaumont enhancement of natural settlements. Although results to and J. Mason. ICES CM 1987/K:3. 31 pp. Carlton, J. T. 1987. Patterns of transoceanic marine biological date have been disappointing, with improved knowledge invasions in the Pacific Ocean. Bulletin of Marine Science, of the environment and with further technological devel­ 41: 452-465. opments, a future for scallop ranching would seem assured. Carlton, J. T., and Geller, J. B. 1993. Ecological roulette: the global transport of nonindigenous marine organisms. Sci­ ence, 261: 78-82. Cochard, J. C. 1987. Observations sûr la viabilité des oeufs de References la coquille Saint-Jacques en Rade de Brest: Analyse des fac­ teurs affectant la croissance larvaire (Observations on the Andersen, S., Burnell, G., and Bergh, 0. 2000. Flow-through viability of eggs of scallop in the Rade de Brest, analysis of systems for culturing great scallop larvae. Aquaculture factors affecting the growth of larvae). In 6th International International, 8: 249-257. Pectinid Workshop. Ed. by A. R. Beaumont and J. Mason. Andrews, W. 1847. The fisheries of the coasts of Ireland. ICES CM 1987/K:3. 31 pp. Pamphlet addressed to Sir James Ussher, Dublin. 16 pp. Comely, C. A. 1972. 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