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1.
The effects of dietary mannan oligosaccharides (MOS) on the survival and growth of Astacus leptodactylus juveniles were evaluated. Experimental diets were prepared by using supplementation of 0 (Control), 1.5, 3.0, and 4.5 g MOS kg−1 commercial trout larvae diet containing 43 g kg−1 protein and 15.74 g kg−1 lipid. A. leptodactylus juvenile with an average total length of 3.6 ± 0.46 cm (TL) and average weight of 1.25 ± 0.43 g was stocked in 0.2-m2 aquariums at a rate of 50 crayfish/m2 and reared for 60 days at 22.8°C. The experiment consisted of four treatments with three replicates each. Each aquarium contained ten crayfish. Crayfish juvenile fed with 0, 1.5, 3.0, and 4.5 MOS attained 6.15 ± 0.49, 5.94 ± 0.29, 7.34 ± 0.39, and 5.94 ± 0.27 cm final total length and 50, 56.67, 46.67, and 50% survival rates, respectively. Moreover, molting frequencies in 0, 1.5, 3.0, and 4.5 g kg−1 MOS groups were detected as 44.44, 61.11, 83.33, and 38.88%, respectively. At the end of the experiment, a general enhanced growth performance (P < 0.05) and feed conversion ratio were observed in crayfish fed on the diet containing 3.0 g kg−1. Crayfish juveniles fed with 3.0 g kg−1 MOS had the highest final length (7.34 ± 0.39 cm), although their survival was the lowest (46.67%) compared to other treatments but not significant. Specific growth rates were significantly different (P < 0.05) among the treatment groups at the end of the 60-day experiment. There were no significant differences (P > 0.05) in percentage moisture, protein, and ash (wet-weight basis) in the tail meat of A. leptodactylus juvenile among treatments (diet) that averaged 82.3, 16.1, and 1.2%, respectively. However, lipid value was significantly different among the diets P < 0.05), with values between 0.13 and 0.32. From the current results, it could be advised to use MOS at the rate of 3.0 g kg−1 in A. leptodactylus juvenile diets.  相似文献   

2.
Recent advances in intensive rearing of astacid juvenile crayfish have greatly improved the results. This challenges the current application possibilities of the studies performed previously, and new research on density is required. A 100-day experiment was carried out under controlled conditions to evaluate density effects on survival and growth rates of juvenile crayfish in optimal conditions of feeding. Juvenile stage 2 Pacifastacus leniusculus were stocked in fibreglass tanks (1 m2, 200 l water) at 20 ± 1°C and fed a dry diet for salmonids supplemented with restricted amounts of Artemia nauplii. Stocking densities were 100, 300, 600 and 1,000 crayfish m−2. Mean survival rate was reduced significantly with increased stocking density, ranging from 86.33% (100 m−2) to 39.13% (1,000 m−2). All checks showed that at the lowest initial density (100 m−2) animals grew significantly faster those at higher densities, recording a final carapace length of 15.28 mm and weight of 1.08 g. Among the treatments of 300, 600 and 1,000 m−2 no differences were found either in carapace length or in weight throughout the experimental period, with a final mean growth of 14 mm carapace length and 0.72 g weight. The final proportion of animals with chelae autotomy rose significantly with increasing stocking density, ranging from 14.44% (100 m−2) to 41.45% (1,000 m−2). This study shows that diet is a decisive factor for stocking successfully high densities under controlled conditions and provides useful information to set adequate densities in accordance with the production objectives.  相似文献   

3.
The freshwater crayfish industry in Britain is based on two species, Pacifastacus leniusculus (Dana) and Astacus leptodactylus Eschscholtz, which were introduced during the 1970s and 1980s. The former is widely cultivated but both are also established in the wild, from where they are harvested. Very few studies have been made of the meat yield in these two species and none on British populations. Two essentially wild populations were assessed for their meat yield. Due to its more massive claws male P. leniusculus had a higher meat yield than male and female A. leptodactylus and female P. leniusculus in both winter and summer months. Less difference was found between the yield of tail meat between the sexes and species. Compared with other studies, meat yield in the two British populations of P. leniusculus (11–15%) and A. leptodactylus (9–13%) would appear to be lower; possible reasons for this are discussed. However, expressing meat yield as a percentage of wet body weight, although useful for comparative purposes, can give conflicting results – examples of this are given. Meat yields from the claws of the two species indicated that positive allometric growth continued after sexual maturity.  相似文献   

4.
Effects of size grading and stocking density on growth and survival of 3.5‐month‐old signal crayfish (Pacifastacus leniusculus Dana) juveniles were investigated in a 3 × 2 factorial design with size group (small, large and mixed) and stocking density (25 and 200 individuals m?2) as factors for 90 days. Carapace length and wet weight growth of the juveniles were affected by the presence or absence of other size groups, stocking density and animal size. All factors had statistically significant interactions, which make the interpretation of the results more complicated. The smaller crayfish grew faster in the absence of large animals and larger animals benefited from the presence of smaller cospecies. Increasing density decreased the growth in length and weight. Survival (82–100%) was good in all groups. Subsequently, the within population dynamics was studied by selectively removing the largest individuals (selectively removing (SR) group). Effects on growth and survival of the remaining juveniles were evaluated on 6‐month‐old P. leniusculus juveniles reared in plastic tanks (100 juveniles m?2) for 122 days. Size distribution manipulation was performed at days 34 and 70. Juveniles in SR group grew significantly faster in comparison with a control group (RR), from which juveniles were removed randomly. Also, the survival rate was significantly higher in the SR group than in the RR group. In conclusion, size grading of juvenile P. leniusculus either at the start of the experiment or repeatedly during the experiment increased growth performance of smaller animals in length and weight.  相似文献   

5.
New and viable species for aquaponics and integrated multi‐trophic aquaculture (IMTA) in freshwater systems can improve yields and sustainability of aquaculture. Freshwater crayfish species such as Astacus astacus and Pontastacus leptodactylus are omnivorous feeders and considered candidates for feeding on faecal matters in existing aquaculture systems. Feeding trials were conducted to determine growth response and RNA/DNA ratio in freshwater crayfish fed fish waste. Carapace length and wet weight were measured to determine the growth response. Juvenile A. astacus was fed faeces of hybrid striped bass (Morone chrysops × Morone saxatilis) and rainbow trout (Oncorhynchus mykiss), while adult P. leptodactylus was fed with two commercial pellet diets and pikeperch (Sander lucioperca) faeces. The nutritional composition of hybrid striped bass faeces was close to optimal diet composition of A. astacus, and crayfish showed significantly higher carapace growth, weight gain and weight gain per moult as the group fed rainbow trout faeces. The growth of P. leptodactylus was significantly lower in terms of weight gain and weight gain percentage per moult for crayfish fed on pikeperch faeces. Thus, this study can recommend a co‐cultivation of hybrid striped bass and A. astacus within one system, but cannot recommend co‐cultivation of P. leptodactylus with pikeperch. Additionally, this study showed controversial results of RNA/DNA ratio and weight gain of both crayfish species. Thus, RNA/DNA ratio cannot be approved for investigations on crayfish physiological status in controlled feeding experiments if animals are fed with an inadequate diet.  相似文献   

6.
In 1984, 40 mature and 100 immature signal crayfish, Pacifastacus leniusculus (Dana), were introduced into the River Great Ouse, England. By 1994, the population had spread up and down stream to occupy an 11.4 km river section. The estimated density and biomass (wet weight) of the population in 1993 were highest in summer at 4.0 m–2 and 133 g m–2 respectively, with annual means of 2.2 m–2 and 82 g m–2 for crayfish of >30 mm carapace length (CL) in the pool (P2) where the crayfish were originally introduced. Density and biomass were 15 m–2 and 78 g m–2, with annual means of 6.1 m–2 and 33 g m–2 for crayfish of all sizes in a riffle 300 m downstream from P2. An annual survival rate of 14% was estimated for crayfish >30 mm CL in P2 in 1993. The relative abundance estimated for six riffles and six pools in 1994 showed that crayfish abundance decreased gradually from the original site of introduction both up and down the river. Estimated annual production of crayfish >35 mm CL in P2 for 1993 was 52.58 g m–2 WW, with a turnover ratio (production/biomass) of 0.44.  相似文献   

7.
Potential fecundity of an introduced population, Keban Dam Lake, Elazı , Turkey, of freshwater crayfish, Astacus leptodactylus leptodactylus (Esch., 1852), was investigated in the present study. The results showed that there was not a linear relationship between female size and pleopodal egg number. The results also showed that although there is an increase in the mean pleopodal egg number with an increase in size (carapace length, CL), it is not the most important factor affecting potential fecundity in A. leptodactylus (slope=1.9294). Mean pleopodal egg number was 305.93 (S.E.=8.82) for the size range of 47–76 mm CL (N=96). The maximum pleopodal egg number was 588 for the crayfish in a 72-mm CL. The present study showed that Keban Dam Lake population of A. leptodactylus has more potential fecundity than the other populations in Turkey. The egg-bearing capacity of female A. leptodactylus caught from Keban Dam Lake could improve efficiency in controlled hatchery production of juveniles.  相似文献   

8.
Herbals such as Cynodon dactylon, Piper longum, Phyllanthus niruri, Tridax procumbens, and Zingiber officinalis were extracted with acetone, benzene, butanol, and petroleum ether and screened against the pathogen Vibrio harveyi isolated from the infected Grouper Epinephalus tauvina. Among the different solvent extractions screening to V. harveyi, petroleum ether extracts were suppressed significantly (P < 0.05). Equal proportions of the all-plant extracts were mixed with the artificial feeds at concentrations of 100, 200, 400, and 800 mg kg−1 of diet and fed to grouper juveniles of 20 ± 2 g average weight for a period of 60 days. Every 20 days, fish juveniles were challenged with V. harveyi and the immune response was studied. The herbal diets significantly (P < 0.05) increased the survival, growth, and immune responses compared to the control group. The herbal diets were significantly improved (P < 0.01) in immune parameters such as phagocytic activity and albumin–globulin (A–G) ratio. Among the different concentrations of the herbals in the diet, the 400 mg kg−1 diet was the most effective in the experiment.  相似文献   

9.
Increased market demand for algal raw materials has stimulated research and development into new cultivation technologies, particularly in countries with economically important seaweed industries. Chondrus canaliculatus is a red alga endemic to the temperate Pacific coast of South America and produces a complex carrageenan. In Chile, this potential marine resource has been underutilized since the early 1990s, after it was replaced mainly by imports of Kappaphycus and Eucheum from Asia. The study of the cultivation of C. canaliculatus in outdoor tanks demonstrates the potential to produce large quantities of algal material due to the high productivity observed. The material produced may be important in Chile as feed for cultured algal herbivores such as Haliotis spp. Data were obtained on the key factors affecting the growth of this alga, including light, temperature, and nutrient concentrations. The results showed that, on a dry weight basis, productivity varied seasonally between 40 g m−3 wk−1 in autumn and 200 g m−3 wk−1 in spring, and the optimal stocking density in our experiments was 8 kg m−3. Effects of self-shading were among the most important limiting factors in the culture. Discussion is presented on the interactions between temperature, pH, salinity, enrichment with N and P, and water exchange on the maximal growth of C. canaliculatus in this culture.  相似文献   

10.
Bacillus subtilis isolated from the intestine of Cirrhinus mrigala (Hamilton) was incorporated into the rearing water of Poecilia reticulata (Peters), Poecilia sphenops (Valenciennes), Xiphophorus helleri (Heckel) and Xiphophorus maculatus (Gunther) at four different concentrations (5 × 108 cells ml−1, 5 × 107 cells ml−1, 5 × 106 cells ml−1 and 5 × 105 cells ml−1) and its effect on fish growth performance and survival, water quality parameters and bacterial population of water were assessed. The results showed that the addition of bacterial cells in the rearing water resulted in greater survival and a faster growth rate and, hence, greater length and weight increments of the livebearers. The use of a bioaugmentor in the rearing water of the livebearing fishes resulted in significantly lower (P < 0.05) concentrations of dissolved organic matter and total ammonium nitrogen. The counts of motile aeromonads and total coliforms recorded in the water of bioaugmented tanks were also lower than that in the control tank. Bioaugmentation between 106 and 108 cells ml−1 in the rearing water is sufficient in establishing a bioaugmentor and the use of a higher concentration of bacterial cells did not always lead to significantly better results.  相似文献   

11.
《水生生物资源》1999,12(6):387-401
Signal crayfish (Pacifastacus leniusculus) originating from Lake Tahoe, California, were introduced into Karisjärvi, a small (11 ha) lake in central Finland (61° 58'N, 25° 32'E), in 1968 and 1969. Since then, the population has been monitored regularly by trap catches. The stocked signals (3–5 years old) were caught until 1973, by which time they had reached ages of 7–9 years. Catches have increased slowly since the early 1980s, the peak occurring in 1991 at 2.0 individuals per trap per night. The population size was estimated as 60 trappable specimens in 1974, 95 in 1981 and 420 in 1988. The mean density of adult population in suitable biotopes was low, 0.07 specimens per m–2, or 0.3 per shore metre, in 1988. The slow development of the P. leniusculus population has been attributed to environmental factors, mainly the limited area of good crayfish habitat. More than 90 % of all signal crayfish were caught in one-third of the shore area, i.e. in steeply sloping lake beds suitable for burrowing or rich in shelters such as rocks and submerged trees. The signals avoided flat, soft bottoms. Fifty per cent of the female P. leniusculus matured at 90 mm TL (smallest 64 mm), i.e. half of the females entered the breeding population in the autumn of their fourth year. The mean size of newly hatched (stage 2) juveniles was 9.7 mm TL and of one-summer olds 30.3 mm. The largest specimen trapped measured 159 mm. The signal crayfish imported into Finland and stocked were infected with crayfish plague (Aphanomyces astaci), but no mortality has been recorded. Two Branchiobdellidae (Annelida, oligochaeta) epibiont species new to Finland were imported from North America with P. leniusculus. The continuous occurrence of these commensals in the signal crayfish population indicates that they have adapted to Finnish conditions.  相似文献   

12.
The shore crab Carcinus maenas is a commercially important species, utilised as sea angling bait as well as supporting a European-wide fishery. Hatchery production could provide an alternative source of bait crabs, alleviating potential competition between these sectors and environmental concerns regarding bait collection practices. A series of experiments were carried to investigate the potential for hatchery production, focusing on effects of dietary regimes and stocking densities through the zoeal stages and the influence of tank substrates and stocking density during the megalopa stage. Inclusion of the rotifer Brachionus plicatilis as live food for early larval stages conveyed no advantage in terms of survival or rate of development compared to a diet of Artemia nauplii. Increasing zoea stocking densities (from 94 to 557 l−1) had a significantly negative effect upon survival to the megalopa stage (from 75% down to 47%), although this was off-set by a significant increase in production, with 260 megalopae−1 produced from an initial density of 557 zoeae l−1. The inclusion of substrates for megalopa stages had no impact on production or development rate, compared to tanks with no substrate. The completely benthic behaviour of megalopae indicates that tank floor area will be a limiting factor for crab production. Increasing stocking density of megalopae was found to significantly and negatively influence survival, although above 10,000 megalopae m−2 the rate of decline in survival stabilised and maximum production (3,114 juveniles m−2) of juvenile crabs could be achieved at the highest stocking densities tested (40,000 m−2).  相似文献   

13.
Two trials were carried out in the laboratory in order to assess the effect of microparticulated feed (F) and live (Thalassiosira pseudonana, M) diets on the growth of recently set (396 ± 13 μm shell height) and 2 mm Crassostrea gigas postlarvae. Different proportions of M and F (100:0, 75:25, 50:50; 25:75, 0:100) were delivered in a single dose of 3 h d−1 in trial 1. Dietary M:F proportions of 100:0, 50:50, and 0:100 were delivered as a single pulse of 8 h d−1 (P1) or two pulses of 4 h−1 (P2) in trial 2. Maximal daily M ration was 296 cells μl−1 d−1 (trial 1), 150 M cells μl−1 d−1 (trial 2), or their equivalent F dry weight. Shell height (SH), dry (DW), and organic weight (AFDW) were evaluated weekly. Oysters from trial 1 significantly increased their size after 28 days, and exhibited no significant dietary differences in terms of DW (1.21 ± 0.15 to 2.01 ± 0.28 mg) or AFDW (0.091 ± 0.022 to 0.166 ± 0.029 mg). Newly set postlarvae (trial 2) also exhibited significant growth after 25 days. No dietary differences were observed in trial 2, yet P2 oysters attained significantly higher shell heights (825–912 μm) than P1 oysters (730–766 μm) after 25 d. Pulse effects were marginally not significant in terms of AFDW and growth rate. Together, these findings showed that balanced microfeeds have a practical potential for the culture of early C. gigas postlarvae, when they are delivered in pulse-feeding schemes  相似文献   

14.
The agarophyte Gracilaria birdiae Plastino & Oliveira was cultivated under field conditions in an estuary over a 6-month period. Biomass production varied significantly (p<0.01) and ranged from 900.0 to 3537.0 g m−2 with a mean of 2124.4±1004.36 g m−2 over the cultivation period. The epiphyte-biomass varied from 64.7 to 313 g m−2, with maximum values observed in July. Relative growth rate (RGR) of G. birdiae varying from −0.59 to 4.67% day−1, with a maximum mean observed in July. Correlation analysis showed that RGR was positively correlated with epiphyte-biomass (R-Pearson=0.69; p< 0.01) and negatively correlated with salinity (R-Pearson=−0.41; p<0.05). These correlations were used in a mathematical regression model to estimate the growth of Gracilaria in an estuary. The regression model explained 61% of RGR variability demonstrating that growth rates of Gracilaria were directly related to the variables salinity and epiphytes. The model was developed to help to predict production at a cultivation site in order to evaluate its suitability for Gracilaria cultivation.  相似文献   

15.
The effects of two alternative prey (crayfish and hake) were tested on growth and survival of both juveniles and adults of Octopus vulgaris in two experiments. Octopuses fed the control (squid) were larger (3.0 ± 0.7 kg) than those fed crayfish (2.4 ± 0.6 kg) at the end of experiment I. Similarly, overall growth rates were higher for octopuses fed squid (1.7 ± 0.3 and 1.2 ± 0.2 %BW day−1, respectively). Average feeding rates for the experiment were not different, being 6.5 ± 0.9 and 7.5 ± 0.9 %BW day−1, respectively, for octopuses fed either squid or crayfish. Nevertheless, food conversions for the experiment were higher (42.4 ± 2.7%) for octopuses fed squid compared to the ones fed crayfish (23.9 ± 1.9 g). For experiment II, hake and crayfish were compared to squid; the final weight of octopuses fed squid, hake or crayfish was 1,183.0 ± 242.7 g, 1,175.6 ± 240.1 g and 922.3 ± 160.1 g, respectively. Overall growth rates for the experiment were 1.9 ± 0.2 %BW day−1, 1.9 ± 0.3 %BW day−1 and 1.1 ± 0.3 g, respectively. Final weight and growth rates were never different (P > 0.05) between octopuses fed squid and hake, but were always higher (P < 0.05) compared to the ones fed crayfish. Average feeding rates for experiment II were similar for the three diets, and of 4.6 ± 1.5, 4.2 ± 1.3 %BW day−1 and 5.1 ± 0.9 %BW day−1, respectively, for octopuses fed squid, hake or crayfish. Food conversions for experiment II were of 41.0 ± 9.6%, 40.5 ± 9.9% and 21.3 ± 7.4 g, respectively, for octopuses fed squid, hake or crayfish, and were always higher for octopuses fed squid and hake compared to crayfish. The results indicate that crayfish is not an adequate replacement for the usual prey to fatten octopus, even considering its much lower market price.  相似文献   

16.
The aim of this study was to evaluate the effects of practical diets with different levels of vitamin A on survival and growth of juvenile crayfish (Pacifastacus leniusculus). An 80‐day trial was conducted with stage 2 juveniles from the onset of exogenous feeding. Four diets differing in the level of retinyl acetate were tested: 0, 0.0025, 0.0050 or 0.0100 g kg?1 diet, equivalent to 0, 2500, 5000 or 10 000 IU vitamin A kg?1 diet, respectively. Each diet was tested on grouped or individually isolated crayfish. Crayfish fed the diet with 5000 or 10 000 IU vitamin A kg?1 diet achieved the highest survival (average of grouped and isolated: 88.9%) and growth (grouped and isolated: 13.45 mm carapace length, 533.4 mg weight). Final growth of isolated crayfish was significantly higher than that of grouped crayfish for all diets. This study provides the first data on vitamin A requirements of freshwater crayfish. A level of 5000 IU vitamin A kg?1 can be recommended for juvenile P. leniusculus during the first period of intensive rearing.  相似文献   

17.
This review focuses on the present distribution of populations of the crayfish Astacus leptodactylus that are harvested in Turkey. It also examines the history of this harvest and the impact that crayfish plague has had on them. Crayfish plague, caused by the fungus-like organism, Aphanomyces astaci Schikora, 1906, is a severe parasite of freshwater crayfish and has caused a lot of damage to A. leptodactylus populations in Turkey since 1984. Turkey was the largest provider of A. leptodactylus to Western Europe from 1970 (or possibly earlier) until 1986. For example, the peak production was reached in the early 1980s, with over 5,000 tonnes being exported in 1984. On the other hand, as a result of the crayfish plague the harvest of A. leptodactylus was reduced severely in most populations in Turkey after 1985. The harvest was only 320 tonnes in 1991. After the occurrence of crayfish plague in Turkey, in order to increase crayfish production uncontrolled A. leptodactylus stockings have been carried out in many waterbodies throughout Turkey. These introductions have caused an increase in the number of A. leptodactylus populations, but exploitation of A. leptodactylus is still under the pressure of the plague, although there has been a steady increase in crayfish production in recent years. The harvest increased to 2,317 tonnes in 2004. Fortunately, among those populations affected by crayfish plague, large amounts of A. leptodactylus can still be harvested from three lakes, ?znik (Bursa), E?irdir (Isparta) and Çivril (Denizli). Thus, it seems that A. leptodactylus has a degree of resistance to crayfish plague. It is therefore interesting to investigate the resistance of A. leptodactylus caught from these populations to crayfish plague.  相似文献   

18.
The effect of stocking density on the growth of mulloway, Argyrosomus japonicus, was tested with 17 g fish stocked at 4.08, 8.16, or 16.32 kg m−3 in 50 l aquaria. Weight checks were carried out every 2 weeks to track performance. Each density treatment was also compared to a nonhandled control group to establish if handling during weight checks influenced the growth of mulloway. Mulloway performed poorly at the lowest density and, under the current experiment conditions, growth did not appear to be negatively affected by regular handling.  相似文献   

19.
In the pearl cultivation farms of the Ehime Prefecture, Japan, mass mortalities of the pearl oyster Pinctada fucata have occurred since 1994. The occurrences of mass mortality roughly coincided with a shift of the dominant phytoplankton from Skeletonema and Chaetoceros to Chaetoceros and Nitzschia all of which belong to Bacillariophyceae. Hence, we evaluated Nitzschia, together with Chaetoceros and Isocrysis, as food for the oyster. Wet weights, lengths, widths, glycogen contents, and growth rates in terms of wet weight of the oysters in all the feeding treatments were significantly higher than those in the non-feeding treatment. The highest glycogen content (2.34%) and growth rate (2.21 g month−1) were found in the Chaetoceros treatment. Growth rate in the Isocrysis treatment (1.63 g month−1) was also high, although glycogen content in this treatment (0.41%) was low. In the Nitzschia treatment, growth rate of the oyster (0.94 g month−1) was the lowest and glycogen content (0.83%) was also low relative to that in the Chaetoceros treatment. Chlorophyll a concentration in fecal pellets was lowest in the Nitzschia treatment (<2.7 μg mg−1), suggesting more complete digestion of Nitzschia by the oyster. Thus, Nitzschia was edible and digestible but not assimilated by P. fucata. We propose the following scenario for the relationship between Nitzschia dominance and mass mortality. When Nitzschia dominates in a culture area, the physiological condition of P. fucata deteriorates due to low assimilation of Nitzschia by the oyster, followed by susceptibility of the oyster to infection by agents lethal to the oyster.  相似文献   

20.
The culture of Sepia officinalis hatchlings and juveniles at different densities and enriched environments was investigated. Experiments were conducted to determine effects of culture density and the use of a substrate on growth and survival. Experiment I studied the effect of three different densities (52, 515 and 1544 hatchlings m−2). Experiment II tested the effects of the enriched environment, using a sandy bottom with pvc shelters. Experiment III tested the effects of density on growth, survival, feeding rates and food conversions. Cuttlefish were fed live grass shrimp at rates of 20% body weight per day (BW d−1). Grass shrimp (Palaemonetes varians) was supplied ad libitum as food in all experiments. In experiment I, growth was different between the three densities, with highest growth for density of 515 hatchlings m−2. IGR was of 8.8, 9.6 and 9.2% BW d−1 for the three densities tested, respectively. Both groups of experiment II had similar growth. IGR was of 10.1 and 9.7% BW d−1 for enriched and non-enriched environments, respectively. Densities of 10, 45 and 120 juvenile m−2 were used in experiment III. Significant differences in feeding rates were only found between densities of 10 and 120 cuttlefish m−2 during the last week. Results indicate that culture of cuttlefish hatchlings could be done in a non-enriched environment, with densities not exceeding 500 hatchlings m−2 and minimum bottom areas of about 600 cm2. Densities of 120 juveniles m−2 in a minimum area of about 1083 cm2 should be considered for juveniles between 5 and 25 g. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

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