Shallow Raceway Asa Solution to Compact Resource-Maximizing Farming Procedure for Marine Fish Species

......

International Council for the C.M.19981L:2 Exploration of the Sea Theme Session (L) Marine Fish beyond the Year 2000: Technological Solutions for Biological Challenges

Shallow Raceway asa Solution to compact Resource-Maximizing Farming Procedure for Marine Fish Species

Victor 0iestad1 Norwegian College of Fishery Science University of Tromso N-9037 Tromso - Norway

ABSTRACT

The purpose of the project has been to develop a very compact farming system. It has been tested on five flatfish and three bottom-dwelling species, but also on three open-water species. The main effort has been on turbot, Atlantic halibut and spotted wolffish. The system is almost a standard raceway, but wiili very low water level (7 mm for fish at about 100 mg, 25 cm for fish above 2 kg). The system is a package with some crucial preconditions. These include high fish density (often 100-500 kgm-3), no counter-current in the leveled raceways (no jet-currents), adjusting of water intake wiili ilie most remote fish in mind and feeding wiili floating pellets; self-cleaning is obtained easily in ilie system. 2 2 The system has been tested for a wide size-range of raceways (0.07 m to 80 m ) and fish sizes (2 mg to >10 kg), normally wiili results as good as wiili traditional rearing systems with respect to growili and survival rates. There seems to be a "learning window"; ilie earlier the fish are introduced to shallow raceways, ilie better they perform. The results seems to indicate iliat it is possible to produce a variety of fish species in shallow raceways; iliese can be stacked in racks which facilitate reuse of water from level to level. A very compact and costCefIective farming system will be ilie outcome.

Keywords: cost-efficient, floating feed, halibut, self-cleaning, shallow raceway, turbot, wolffish

1 E-mail address:[email protected]

1 INTRODUCTION

Few terrestrial animal species have made their way into large-scale culture for food, although agriculture has been undertaken for 10,000 years. A similar long-term development for a limited number of aquatic animals is expected, but for a long time to come, a multitude of aquatic species are likely to be brought Into culture, including representatives from all temperature zones. A variety of rearing systems will also be applied, partly dictated by the specific demands of the reared organism. Some' systems with be low-cost and low-intensive while others will be highly intensive and sophisticated, often depending on a recirculating water system and formulated food. An increasing part of the farming. activity might develop in the direction of food production industry, in parallel to industrial chicken and turkey production. This sector of the fish production might be less confined to traditional rural locations, as its facilities often may be installed close to the market and even within city borders. Numerous research facilities in industrilized countries are undertaking studies to enable their fish-production industry to launch new rearing concepts suited for industrial food production (Reinertsen et al. 1993). The main characteristics of this industry will be extreme compactness, intensive use of all involved resources, use of pure oxygen and low-pollutant formulated food, and strict prophylactic measures. Most likely, a small number of fish species will dominate in this future industrial fish production.

In Norway, a modest R&D programme has been underway since 1988 to explore the potential of very shallow raceways as the basic farming unit for this type of compact industrial fish production (0iestad 1996). The study has included a variety offish species, both open water species [Atlantic cod (Gadus morhua), presmolt Atlantic salmon (Salmo salar) and white seabass' (Atractoscion nobilis)], bottom dwellers [common and spotted wolffish (Anarhichas lupus and A. minor) and lumpsucker (Cyclopterus [umpus)] and flatfish species [Atlantic halibut (Hippoglossus hippoglossus), turbot (Scophthalmus maximus), sole (Solea solea), Californian halibut' (Paralichthys californicus) and. winter flounder' (Pleuronectes american us )].

The study has been a low-budget activity and many questions have not been addressed properly. The main findings so far will, however, make it possible to evaluate some of the potential of this strategy in· fish production,

MATERIALE AND MEmOD

Initial studies started in 1988 in the company LMC AS at their facility in 0ygarden, outside Bergen. That activity was mainly a test of the basic concept: 125,000 juvenile turbot weighing about 1 g each

2 The work on white sea bass has been done in cooperation with Hubbs-Sea World Research Institute at their Marine Fish Hatchery in Carlsbad, California.

3 The work on Californian halibut has been in cooperation with The Halibut Research Project at . Natural History Museum of Los Angeles County at their facility in Redondo Beach, LA., and with Hubbs-Sea World Reseach Institute at their Marine Fish Hatchery in Carlsbad, California.

4 The study is carried out at University of New Hampshire at their Coastal Marine Laboratory in Portmouth.

2 were transferred to a 2 m wide, 20 m long raceway with a water depth;of 5-10 cm (tank depth 25 em). The test was terminated when the juveniles reach a meanWei@1tof 3 g and were sent by truck to turbot farms in Spain. Seven .years then passed before a larger system was constructed than the one used in 1988. Most of the systems applied throughout the years, have been small experimental units.

Most ofthe results from shallow raceway studies has not been published. They are primarily presented as master degree works at The Norwegian College of Fishery Science at the University of Troms0. Most of the studies have been carried out at The Aquaculture Station in Troms0 at Ringvassey in Troms county (700 N).

Tank design The basic tank design is rather simple. The tank has a rectangular bottom, narrow width relative to length,.and a screen at each end to shield the· water inlet and outlet from the chamber with fish (Cripps & Poxton 1992, 1993). The tank Should, irrespective of size, be completely leveled in its whole length. The smallest units, for larvae and juvenile fish, have been gutters, 7 cm wide with a potential depth of5cm and.with any desired length up to 300 cm. The largest unit tested, for large Atlantic halibut, has been 20 m long and 4 m wide with 25 cm water depth ..

Water transport aspects Correct introduction of water is a challenge. All types of jet current should be prevented, since any jet current will be compensated for by a counter-current in the fish chamber. The water inlet chamber thus must be designed to remove energy from the water and present a homogeneous current pattern at the entrance screen; A strategy to achieve this might be to have large openings in the introduction pipe to permit low water-speed at entrance and directing all incoming water away from the screen; filling the water inlet chamber with bio-bodies of plastic will further promote a homogeneous pattern, although this might represent a hygienic disadvantage.

The end· screen in not a necessity, as the stand-pipe might be Shielded to prevent fish from blocking it. With that approach, all particulate material would be easily transported away with the flow of water. With an end-screen, sedimentation will built up behind it unless special measures are taken to prevent it. If the outgoing water is to be reused after oxygenation, the need for a complete and immediate removal of particulate matter from each rearing unit might demand either that the outlet be within.the fish chamber or that flocculation takes place on the far side of the end-screen.

The current-speed in a shallow raceway is a compromise involving a number of factors. As the floating food is transported with the water, the speed should not transport the food out of the unit too fast. The oxygen needs of the ; biomass in the chamber put a minimum limit on water renewal. The self-cleaning of the raceway is partly dependent on the current speed, but with appropriate fish densities, the limit has been at about I cm/s. The water current speeds in raceways have typically been l from 0.7 cm to 5 cms· .

Food characteristics Shallow raceway's water depth have ranged from 7 mm to 25 em depending on fish size. As a result food particles will pass the vision field of any fish, even those resting on the .bottom. To make food more easily available along the . length of the raceway, floating formulated pellets have ·been used as the main staple food. With small juveniles. (wet weight from 2 to 100 mg), live food organisms have been used, such as natural zooplankton, Artemia nauplii and yolk-sac larvae of cod. These food organisms will drift slowly into the vision-field of the juveniles.

Fish sizes tested Shallow raceway studies have been made with fish smaller than 100 mg, such as metamorphosing

3 Atlantic cod, Atlantic halibut, turbot, sole, Californian halibut, winter flounder and white sea bass. Th e largest fish kept in shallow raceways have beenbroodstock turbot (up to 8 kg), halibut (up t08 kg) and spottedwolffish (beyond 10 kg). Table I reviews most of the fish species studied and their respective size. ranges.

Fish densities Shallow raceway is a very .compact· reating system,andfor that reason the fish density expressed as 3 kilograms per volume·unit might be as high as 800 kgm· • However, in many instances, particularly when dealing with flatfishes and bottom-dwelling fishes, the density should rather be expressed· as 2 density per m • Table I indicates typical fish densities in studies with different species and stages.

Self_cleaning Industrial fish production should take place with almost no cleaning needed in the rearing tanks. In most of the studies, almost complete self-cleaning in the fish chamber has been achieved as a combined effect of a rectified water current and fish movements. High fish density contributes to speed up the prosess, as do temperatures close to growth rate optimum when ·fish are more active.

RESULTS AND DISCUSSION

Tank design The original raceway, designed in 1988, was made by fibreglass reinforced plastic, from elements2m wide and 3 m long puttogether to a 20-m-Iong raceway. The original frame has been used repeatedly to make new units; its color has beeR' changed from grey to brown.

The first unit was put on top of a firm, carefully leveled ,bed of sand. Sand beds have been used for out door raceways in only one level. To prevent severe cooling of the bottom of the raceway in winter, Styrofoam plates have been put between the sand bed I and the tank bottom as insulation. Tile cold could otherwise harm bottom-dwelling fish, which will have no water between the plastic bottom and their skin.

Any division into more than one fish chamber in .a raceway has been for reasons other than to prevent heavy accumulation, as no flatfish· or bottom-dwelling species have ever had a tendency to over-accumulate. Rather, they spread out; even at feeding, they will wait for the food to pass their spot in the tank.

The front screen is used to prevent fish from entering the water introduction chamber. Normally the screen has been of perforated PVC or corrosion-resistant metal. The screen should have no cutting edges to prevent fish from being wounded when coming in contact with any part of it. The mesh size should also prevent floating food from entering the front chamber with occasional counter-currents in the surface. In some recent studies the front screen has been omitted.

The end screen, if any, should have some of the same characteristics, but in general have larger perforation to permit .uneaten food to pass to the outlet. The settling of particles at the bottom of the chamber behind the end-screen, is a challenge for, any commercial operation; in small research studies it has been solved by daily siphoning. For cases in which the water is supposed to be reused or there is restriction on particles in the affluent water from the plant, immediate flocculation by compressed air has been suggested and partly tested.

Without an end-screen no settlement of particles will take place. The standpipe is designed so particles are removed without any conflict with the fish surrounding the outlet unit. Removal of

4 '-, ...

particles can stiUtakeplace,but separ~ted from the tank, whichmight,for the fish, reduce the noice level from the compressed air., A watetquality modulation stUdy aimed at making water suited for repeated use has indicated that a combined use of airing and oxygenation caused flocculation of particulate matter and reduced. the level of CO2 and ammonia. The oxygenation took place in a standard AGA.cone (Vikingstad 1997).

The shallowness of the tanks might make it possible for fish to jump out of their chamber, either into another tank or fatally to the ground. This has been prevented by coarse nets across the fish chambers. In small units,transparent acrylic plates have been used frequently.

Water transport aspects The configuration and the leveling of the shallow raceway areimportant in determining the current pattern. The longer the raceway relative to its width, the easier it is to achieve a homogeneous current pattern across its width all the way through. Thorough leveling contribute further. However, jet currents have to be prevented even when other measures are taken. In most of the studies, the length-width. relation has been unfavorable mainly due to short length and overall low current speed. Counter_currents reversing the direction of floating food particles have been a frequent concequence. In commercial units, which might be 20 to 100 m long and with fairly high current speed, it should be far easier to obtain a desired current pattern and get rid of counter-current problems altogether.

The current pattern in shallow raceways is turbulent, which ensures almost the same current speed everywhere in the tank, the bottom included. The turbulence is enhanced by· fish movement and, as with flatfish, their uneven surface at the bottom. Complete water renewal and efficient transport of particles are benefits from the turbulent current pattern. With increasing water depth, the current pattern will be less turbulent and increasingly laminar; particularly when dealing with bottom-dwelling fish, the benefits of turbulence will diminish rapidly (Sparboe 1995).

However, ifthe water has been oxygenated, it should not be exposed to strong turbulence to avoid loss of oxygen. The losses of oxygen in oxygenated water in shallow raceways has been studied simulating a 50 m long stretch at three temperatures and with an initial level of 150% saturation. The water was not aggitated and losses· of oxygen were only at about 5% with a water depth of about 5 cm with no fish present in the raceway (Erik Vikingstad; pers. comm.).

Fish species and sizes tested Turbot .. Turbot has .been the. most studied fish species in shallow raceways (Table I). The smallest size group studied had a mean weight of 90 mg. In that forced settlement study, the metamorphosing turbot settled to the bottom far ahead of time due to the shallowness of the tank (water depth was 7 mm). Those offered formulated food had a specific growth rate ( SGR) of II % at onset of the study and a mean SGR of 7% to a weight of 3.8 g (52 days) with 3% mortality, all at 14°C. Weaning was immediate, and the density of fish increased from 8% coverage of the bottom to 100% when th ey reached 3.8 g. The group reach a weight of 12 g at day 78, giving a SGR of 4.5% with 210% coverage of the bottom and with no mortality. The water depth was gradually increased to 25 mm. Throughout the study the fishes spread evenly in the tank with no aggregation. of larger fish, no antagonistic behaviour observed, and no sigu of tails being bitten (Klokseth 1996).

Juvenile turbot with initial weight of 7.3 g reached a mean weight of 13 g after 34 days at 15.3°C with a SGR of I. 7% regardsless of weather their bottom coverage was 100, 200 or 300%. Again, no antagonism and almost no mortality was observed; fish at higher densities were less susceptible to disturbances (Lyngstad 1994). The low SGR, as compared with a more recent study where a SGR of 4% for a siinilar weight range at a somewhat lower temperature, might be explained by the acclimation of

5 the second group to shallow raceways at an early stage. The observation might indicate the exsistence of a "learning window" for optimal behaviour in shallow raceway with floating pellets.

Illumination at 0.16 lux and 1,200 lux gave significantdifferences in SGR values (1.6% and 1.9%; size range 20-35 g) as did the temperatures 15.9°C and 21.6°C (SGRvalues being 1.7% and 2.1%; size range 35-65 g; Lyngstad 1994).

In 'a grading effect study with almost 2,000 turbot, initial sizes ranging from 30 to 410 g, three groups were established, small (146 g), large (236 g) and unsorted (163 g). Their SGRs after 86 days at about 14°C, were not significantly different [0.84% (small), 0.79% (large) and 0.87% (unsorted)), and no positive effect of grading on biomass production revealed. The coefficient of variance gave no indication of social interactions (Strand & 0iestad 1997).

A number of other studies have indicated that turbot can grow fast in shallow and rather narrow raceways (1 m width) beyond 5 kg when offered floating pellets at 13-15°C. Occasionally growth depression is observed, as well as ,atypical fast growth in one or a few parallel groups, deviations we still have no exact explanation for (Vikingstad 1997). The overall performance of turbot is encouraging and make it one ofthe best candidates for shallow raceway farming (0iestad 1996).

Halibut Halibut. has been studied in shallow raceways since 1992, at sizes ranging from 70 mg to 8 kg. In a forced settlement study with 70 mg metamorphosing halibut, the fish settled to the bottom within two days due to the shallow (7 mm water depth) tank. Those offered live cod larvae as food had a SGRas high as .11% at the beginning of the study at 13°C. However, typical SGR values for the 19 days study were about 6% irrespective of whether the food was Artemiaor live cod larvae (Klokseth and 0iestad, in press). Mortality was 1-2% for those offered Artemiaor a mixture of the two diets; those on cod larvae had 28% mortality. Antagonism was observed, particularly among those offered only cod larvae (which was in short supply). Those on a mixed diet segregated themselves by size, with the larger occupying the foremost part of the chamber where the food entered. After removal of the larger fully metamorphosed halibut on day 19, the remaining about 70% were feed for another fortnight, now with no.'mortality and seemingly those recovered that had been suppressed by the larger. halibut as their overall SGR was 5%. In a recent study at The Aquaculture Station Austevoll, successfull weaning was achieved with 70 mg halibut in a similar system (Ingegjerd Opstad, pers. comm.).

Recent studies with juvenile halibut transferred from deep tanks to shallow raceways when they had passed 200 g indicate that halibut might also have a "learning window" for feeding on floating' pellets and for thriving in shallow water (0iestad & Aune 1997). In general, halibut is a more reluctant hunter than turbot; a fraction of the test groups never started to feed, a phenomenon almost unseen in groups being transferred to shallow raceways at metamorphosis. The "barking" behaviour, where a disturbed halibut swims fast while lifting the forebody above the surface, is also far more frequently observed among late transferred groups.

In general halibut seems to be more affected by the farming situation than turbot. However, larger populations of halibut reared from metamorphosis in shallow raceway have been studied only recently; these may be more successful.

Californian halibut and winter flounder Californian halibut metamorphosis at 7-8 mm with a wet weight of 8-10 mg. When transferred to shallow raceways, they settled to the bottom when not fully metamorphosed. When offered enriched Artemianauplii at about 22°C, their SGR was about 20% the first week declining to 12-15% the next two weeks, when their diet was supplemented with frozen mixed-sized Artemia. Early weaning {before

6 100 mg) has not been successfull so far.

Weaning studies undertaken at University of New Hampshire, USA, with metamorphosed winter flounderin shallow raceways during the summer 1998 met with success as they were fully weaned at 70 mg with modest mortality (W. Hunt Howell, pers.comm.).

Common wolffish Common wolffish has been ~tudied from first-feeding in shallow raceway as described by Strand et al. (1996). It has also been studied usingjuveniles collected by trawling with a fine-meshed trawl net in the Porsanger Fjord, Finmark County.

In general, newly hatched (l.8 cm) or wild-caught wolffish juveniles (2-3 cm) can easily be reared on live Artemia naupJii or be. weaned on formulated pellets in shallow mceways. Mashed krill with an alginate binder has also been used .with good results.

An optimization study was carried out starting with three densities, 25, 50 and 100% coverage of the bottom. No difference was observed, as their SGRs was all about 0.7-0.8%. The effect of different light levels (0.1 lux to 500 lux) was negligible, giving SGRs of 0.5-0.6%. The effect of temperature. differences was though significant with 10°C giving the highest SGR (0.6%; 0.2% at 6°C).

In general, common wolffish has a low SGR, even as juveniles. They are rather susceptible to diseases and is rather nervous, reacting strongly to abrupt changes in light level. They are also rather susceptible to eye snapping (pedersen 1995). The species has been dropped from the rearing programme in Norway, although it is still used in a reproduction~strategy study.

Spotted wolffish The first genemtion ever of artificially fertilized eggs from spotted wolffish hatched during the spring of 1994. Since then, five genemtions have hatched, and all have been reared in shallow raceways from first-feeding at 2 cm. The larger ones from the first generation have passed 10 kg, still in shallow raceways, where they snap the floating pellets from the surface while forming dense mats at the bottom, avoiding any open space when given too much surface area (Reinhold Fieler, Akvaplan-niva, Troms0, pers. comm.). They have to be feed the full width of the raceway, as the fish do not move far; the shallow water level prevents them from swimming across others.

At 4 to 8°C, the SGR is rather high from first-feeding (1-3%; Ingrid Lundamo, NFH-UiT0, pers. comm.), and. within four years the mean weight of the first generation had passed 5 kg. The spotted wolffish should not be reared above 10°C due to their susceptibility to atypical furunculosis at elevated temperatures. The autumn 1997 a number of the females ovulated, but no males reached maturation. Almost no mortality has been observed among fish larger than 109.

Spotted wolffish behaviour appears well suited for farming as the fish prefer very dense aggregation of conspecifics and seem to be unaffected by the farming situation and unfrightened by the presence of people; It is the first fish species where all research activity post-hatching has been in shallow raceways, and after five years effort, the species is about to be commercialized in Northern Norway.

Lumpsucker . Lumpsucker larvae have been tranferred at hatching to shallow raceways and reared beyond 109 (SGR first half year about 4%), first on live Artemia naupJii and later on formulated pellets. Its sucking ability from hatching make it easy to rear in shallow raceways at high density.

7 Atlantic cod and white seabass Some few studies have been carried out with cod from a size of 12 mm to 15 cm. Most of them have been distorted by super-saturation of nitrogen in the sea water with resulting swim-bladder problems. In the one without problems, jish density was more than 200 kgm·) and with SGRthe same as'at lower densities and compareable to other juvenile cod studies (1.5 to 3.5%; Folkvord 1991; Otterlei' 1993). The fish stem the current, forming shoals while feeding on the pellets drifting by on the surface. When the cod are properly feed, cannibalism is negligible even in ungraded groups.

The observations made on white seabass, were very similar to those on cod.

Presmolt of Atlantic' salmon The study with salmon suffered from an inappropriate diet, as no truely floating pellet was available from first-feeding. Lack of availability of feed in the surface in the full length of the raceway might have caused the fairly low SGR observed (1. 7% for fish from 2 to 8 g; Brilthen 1997). There was no difference in SGR between fish at about 500 kgm·) and those at less than 100 kgm·) (Sretre 1997). The self-cleaning was better at high density, where the fish formed one dense school in the total space available.

The shallow raceway as a standarized study unit Shallow raceways are fairly easy to standardize for fish rearing studies with respect to vital water quality parameters and parameters like light, current pattern, and current speed. For that reason they have been used in some type of fish studies. It is also easy to manipulate fish densitites within a far larger range than in traditional deep fish tanks. The system has been used on open water species from about 2 mg (white seabass) and on flatfish from 6-8 mg ( Californian halibut); In a future industrial' fish production, high density farming will be the-state-of-the-art from the fertilization stage; that makes it even more desirable to start using shallow raceways on almost any type of fish being studied and ,from the ealiest possible age.

CONCLUSIONS

The application of the shallow-raceway concept in full-scale fish farming is still in an early stage of development. The first few commercial farms are under construction in Norway. In the future these farms may contribute significantly to the further development of the concept, which so far has been tested with promissing results on II fish species, and: with fish ranging in size from 2 mg to above 10 kg. No significant negative experiences have been revealed within the range of fish sizes tested and for the sizes of raceways studied.

The shallow raceway concept is a package containing some essential elements that have to be realized for the system to operate appropriately. If any of these are violated, a number of problems will reduse the efficiency of the system. Attention should be given to fish density, water level, current pattern and speed, to type of food, and water quality, as these affect even the most remote fish in the system. When kept within the recommended'ranges, the system will normally operate smoothly.

It is obvious that flatfish production needs area more than volume. Typically, a 100-tonne annual 2 production of turbot will demand a space of 1,000 m • The same production in shallow raceways in an eight-level rack will reduce the space needed to less than 200 m'. If the sea water can be reused from level to level in the rack, the need for water can be III 0 or less than of a flow-through system. Since the raceways are self-cleaning and self-feeding as the food floats downstream, the need for employees also can be minimal. The cost of production in a full-scale operation would most likely be lower than what is observed with the standard procedure, and there should be a potential for even more cost-

8 effective management.

The construction cost per kg of production capacity can also be reduced compared to the-state-of the-art for other methods. The rack system will make it possible to have a far smaller building, and compactness reduces the logistics of most components, such as piping for water intake and outlet. Reuse of water might cause an overall reduction of pipe dimensions. The rack itself will have modest dimensions and as experience accumulates, both choice of material and the overall dimensions of racks and tanks will be scrutinized to further reduce costs.

The main objection ,to the shallow raceway system has been short reaction time in an emergency situation due to the small water volume in the tanks with its small stored quantity of available oxygen for'thefish. As there potentially are significant savings on investment per kilo production capacity, a fraction of these money could be used to invest in extra safety measures, such as, for example, a duplicate back-up system for electricity.

ACKNOWLEDGEMENT The main research activity has been funded by The Norwegian Research Council, through the projects 1048371110, 104830/110 and 1091251120.

REFERENCES Brathen, K.E. 1997. Egnethet av grunne lengdestromsrenner til oppdrett av juvenile laks (Salmo salar)(in Norwegian; Suitability of shallow raceways in rearing of pre'smolt Atlantic salmon). Cando scient.-oppgave i havbruk, NFH - UiTo, 63 S. Cripps, SJ. & Poxton, M.G. 1992. A review of the design and performance of tanks relevant to flatfish culture. Aquaculture Engineering 11: 71-91. Cripps, SJ. & Poxton, M.G. 1993. A method for the quantification and optimization of hydrodynamics in culture tanks. Aquaculture International I: 55-71. Drawbridge, Mark, pers. comm. Hubbs-Sea World Marine Fish Hatchery, Carlsbad, CA 92008, USA. Fieler, Reinbold, pers. Comm. Akvaplan-niva, N-9005 Tromso, Norway. Folkvord, A. 1991. Growth, survival and cannibalism of cod juveniles (Gadus morhua); effects of feed type, starvation and fish size. Aquaculture, 97: 41-59. Howell, W. Hunt, pers. comm. University of New hampshire, Coastal Marine Lab. Durham, NH 03824, USA. Klokseth, V.H. 1996. Adferd, vekst og overleving hos premetamorfosert kveite og piggvar i grunne lengdestromsrenner (in Norwegian; Behaviour, growth and survival of pre-metamorphosed halibut and turbot in shallow raceways). Cando scient.-oppgave i havbruk, NFH - UiTo, 75 S. Klokseth, V.H. & 0iestad, V. In press. Forced settlement of metamorphosing halibut (Hippoglossus hippoglossus L.) in shallow raceways: growth pattern, survival, and behaviour. Lundamo, Ingrid, pers. comm. The Norwegian College of Fishery Science, University of Tromso, N- 9037 Tromso, Norway.' Lyngstad, 0.1. 1994. Vekstoptimalisering pa ungfisk av piggvar (Scophthalmus maximus) i grunne lengdestromsrenner (in Norwegian; Growth optimization of juvenile turbot in shallow raceways). Cando scient.-oppgave i havbruk, NFH - UiTo, 80 S. Monsaas, Anne Karin, pers. comm. The Norwegian College of Fishery Science, University of Tromso, N-9037 Tromso, Norway. Opstad, Ingegjerd, pers. comm. Austevoll Aquaculture Station, N-5392 Storebo, Norway. Otterlei, E. 1993. Temperatur- og tetthetseffekter pa vekst, overlevelse og kannibalisme hos torskeyngel (Gadus morhua L.) (in Norwegian; Effects of temperature and density on growth, survival and cannibalism among cod juveniles). Cando scient.-oppgave, Universitetet i Bergen, 71 S. Pedersen, A. 1995. Vekstoptimalisering pa ung grasteinbit (Anarhichas lupus) i grunne

9 i,-,

lengdestmmsrenner (in Norwegian; Growth optimalization of juvenile common wolffish in shallow raceways). Cando scient.-oppgave i havbruk, NFH - UiTI!, 85 S. Reinertsen, H., Dahle, L.A.,Jl!rgensen, L. And Tvinnereim, K. 1993. Fish farming technology. Proceedings of the ftrst international conference on ftsh farming technology, Trondheim, Norway, 9- 12 August 1993, 482 pp. Sparboe, L.O. 1995. Matftskoppdrettavkveite i lengdestr0msrenner -en flerfaglig belysning. (in Norwegian; Farming of halibut in raceways - a biological, technological and economical evaluation). Cando scient.-oppgave i havbruk, NFH - UiTI!, 159 S. Strand, H.K., Hansen, T.K., Pedersen, A., Falk-Petersen, J.-B. & 0iestad, V. 1995. First feeding of common wolffish, Anarhichas lupus, on formulated dry feed diets in low water-level raceway system, Aquaculture International 3: 1-10. Strand, HX. & 0iestad, V. 1997. Growth and the effect of grading, of turbot in shallow raceway system. Aquaculture International 5: 397-406. Sretre P.O. 1997. Produksjon av lakseyngel (Salmo salar) i grunne lengdestr0msrenner: effekt· av ekstreme tettheter pa vekst og stl!rrelsesspredning (in Norwegian; Production of pre-smolt Atlantic salmon in shallow raceways: effect of extreme densities on growth and size distribution). Cando scient. oppgave i havbruk, NFH - UiT0, 68 S. Vikingstad, E. 1997. The growth performance of turbot (Scophthalmus maxim us (L.» reared under varying levels of water recirculation. Cando scient.-oppgave i havbruk, NFH - UiT0, 52 S. 0iestad, V. 1995. Vekststudier pa marine organismer i lengdestr0msrenner (in Norwegian; Growth studies on marine organisms in raceways). Sluttrapport for NFR-prosjekt 104837/110 (1992-1994), 17 S. 0iestad, V. 1996a. More farm yield with shallow raceways. Fish Farmer Magazine, Sept./Oct. 1996: p. 24. 0iestad, V. 1996b. Oppdrettskonsept for flekksteinbit (in Norwegian; Rearing concept for spotted wolffish), Sluttrapport for NFR-prosjekt 104830/110 (1993-1995), 11 S. 0iestad, V. & Aune, A. 1997. Kveiteoppdrett i iengdestr0msrenner (in Norwegian; Farming halibutin raceways), Sluttrapport for NFR-prosjekt 109125/120 (1996), 27 s.

10 ,( "

Table I. A review of some of the main works in shallow raceways from 1988 to 1998 in Norway and USA ("). Some of the references are to unpublished reports in Norwegian (0) or to personal communications (p.c.); lO<: only water depth is indicated and not the total tank high.

Species Fish Size Raceway Size in cm SGR Density Reference . WxLxHlO< (min-max) Turbot 0.09-> 12 g 20x60xO.7 (min) 4.5-11% 8->210% Klokseth (1996) 0 1->3 g 200x2000xl0 (max) 4% 200% Victor 0iestad (p.c.) 7-> 13 g 40x360x3 1.7% 100-300% Lyngstad (1994) 0 3 200->320 g 40x360x5 0.3-1.6% 15 kgm·2 (260 kgm· ) Vikingstad (1997) 0 (in English) I 146->800 g 200x300xl0 0.8% 100-200% Strand & 0iestad (1997) 1->8 kg 100x200xlS 100-200% 0iestad(1996a) Atlantic halibut 0.07->0.25 g 20x60xO.7 (min) 6% 8-10% Klokseth and 0iestad (in press) 1-8 kg 400x2000x25 (max) 0.25-0.35% 40-100% 0iestad & Aune (1997) 0 Californian halibut" 8->500 mg 7x200x2 12-20% 30-60% 0iestad (p.c.) I Sole 20->100 mg 20x60xl - - 0iestad (p.c.) Winter .flounder" 30->200 mg 40x400x2 - - W. Hunt Howell (P.c.) Common wolffish 0.2-15 g 20x60xl (min) 0.2-0.6% 25-100% Pedersen (1996) 0 0.2-2.0 g 20xl00x2 5-6% 50-100% Strand et al. (1995) 0.\-3 kg 200x300x10 (max) - 50-100% (500 hm·3) 0iestad (1995· 1996b) 0 Spotted wolffish 0.2-2,000 g 20x60xl (min) 0.5-2.4% 50-100% Ingrid Lundamo (p.c.); 0iestad 5-200 g 40x360xS 1.0-2.4% 50-100% 1996b; Anne K. Monsaas (p.c.) 10 kg 200x2000x25 (max) 0.6% 50-100% Reinhold Fieler (p.c.) Lum~sucker I mg-IOg 20xl 00x2-1 0 4% - Klokseth (1998) 0 . Atlantic cod 8 mg - 10 g 40x200x2 \.5-3.5% 25-220 kgm·' Tvedt (994) 0 White seabass* 0.002-2 g 7xl00x2 (min) 1-15% 1-12 kgm·' 0iestad (p.c.) . 100 g 60xSOOx30 (max) - 10 kgm"3 Mark Drawbridge (p.c.) Atlantic salmon 0.15-2 g 15xl00x3 (min) 1.5-3.0% 20-460 kgm"' Sretre (1997) 0 3 60 g 30x200x10· (max) \.5-2.0% 20-280 kgm- Britthen (! 997) 0