Effects of oxygen supersaturation and temperature on juvenile greenlip, Haliotis laevigata Donovan, and blacklip, Haliotis rubra Leach, abalone

Growth and survival of juvenile greenlip (39.03 (SD 3.80) mm (n=524)) and blacklip (31.92 (SD 4.19) mm (n=531) abalone were investigated at high dissolved oxygen levels (95–120% saturation) between 17 and 19°C. Abalone were fed the same artificial diet and each species was contained in groups of approximately 30 individuals within triplicate tanks for each of six treatments and were exposed to flow through water adjusted to give experimental conditions for up to 75 days. Blacklip abalone held at 16.9°C and 97% oxygen saturation grew in shell length significantly faster than all other treatments of blacklip abalone held at 19°C, and significantly faster than blacklip abalone maintained at 111% oxygen saturation and 17.5°C. Both temperature and oxygen saturation significantly affected the survival of this species. Blacklip abalone held at 19°C had significantly lower survival for both 96% oxygen saturation and 120% oxygen saturation, compared with blacklip abalone maintained at either 110% oxygen saturation and 19°C, or for any 17°C treatment. No significant differences were noted for greenlip abalone within the range tested in terms of growth rate, food consumption rate or survival, indicating that greenlip abalone tolerated these conditions better than did blacklip abalone.     

Terrestrial leaf meals or freshwater aquatic fern as potential feed ingredients for farmed abalone Haliotis asinina (Linnaeus 1758)

Three terrestrial leaf meals, Carica papaya, Leucaena leucocephala, Moringa oliefera and a freshwater aquatic fern, Azolla pinnata were evaluated as potential ingredients for farmed abalone diet. All diets were formulated to contain 27% crude protein, 13% of which was contributed by the various leaf meals. Fresh seaweed Gracilariopsis bailinae served as the control feed. Juvenile Haliotis asinina (mean body weight=13.4±1.6 g, mean shell length= 38.8±1.4 mm) were fed the diets at 2–3% of the body weight day^–1. Seaweed was given at 30% of body weight day^–1. After 120 days of feeding, abalone fed M. oliefera, A. pinnata‐based diets, and fresh G. bailinae had significantly higher (P<0.01) specific growth rates (SGR%) than abalone fed the L. leucocephala‐based diet. Abalone fed the M. oliefera‐based diet had a better growth rate in terms of shell length (P<0.05) compared with those fed the L. leucocephala‐based diet but not with those in other treatments. Furthermore, protein productive value (PPV) of H. asinina was significantly higher when fed the M. oliefera‐based diet compared with all other treatments (P<0.002). Survival was generally high (80–100%) with no significant differences among treatments. Abalone fed the M. oliefera‐based diet showed significantly higher carcass protein (70% dry weight) and lipid (5%) than the other treatments. Moringa oliefera leaf meal and freshwater aquatic fern (A. pinnata) are promising alternative feed ingredients for practical diet for farmed abalone as these are locally available year‐round in the Philippines.     

Comparative performance of juvenile red abalone, Haliotis rufescens, reared in laboratory with fresh kelp and balanced diets

Juvenile Haliotis rufescens were reared in the laboratory in order to investigate the extent to which fresh kelp and formulated feeds with 250 g kg⁻¹ (25P) and 380 g kg⁻¹ protein content (38P) affected their growth rate, gut residence time (GRT), food consumption ( C ), food conversion ratio (FCR) and digestibility. Abalone from 38P attained the highest growth rate (70.5 ± 4.2 μm day⁻¹; 98.3 ± 6.95 μg day⁻¹), followed by 25P (47.9 ± 2.79 μm day⁻¹; 67.4 ± 2.82 μg day⁻¹) and kelp (23.6 ± 3.36 μm day⁻¹; 28.2 ± 4.11 μg day⁻¹). No significant differences were observed in consumption rate among treatments (0.61–0.68% body weight per day), yet kelp-fed abalone exhibited higher FCR (2.44), protein efficiency ratio (4.42), and apparent digestibility of dry matter (69.5%), protein (69.8%) and gross energy (79.2%) than 38P organisms (59.8, 62.4 and 62.2%, respectively). They also showed longer GRT (23.1 ± 0.93 h). This study demonstrated that formulated diets with 250 g kg⁻¹ and 380 g kg⁻¹ protein inclusion can sustain higher growth rates of juvenile H. rufescens than fresh algae. These differences seem to be due to the amount of dietary protein. Kelp meal appears to improve the consumption and digestibility of balanced diets, and its inclusion in formulated diets is recommended.     

Optimum dietary crude protein level for growth in South African abalone (Haliotis midae L.)

A 95‐day feeding trial was conducted to evaluate the effects of dietary crude protein level on total body weight gain and protein gain of juvenile (4.89 ± 0.57 g) South African abalone (Haliotis midae). Six semi‐purified diets containing casein, fish meal and cottonseed meal as protein sources, and with crude protein levels ranging from 54.8 to 479.2 g kg^?1 dry matter (DM), were fed to four tanks containing 30 abalone each in a continuous flow system. No differences (P > 0.05) were found in moisture, ash or lipid content of soft‐body tissue as dietary crude protein level increased, indicating that differences (P < 0.05) in soft‐body protein content were solely due to dietary crude protein level. The relationships between dietary crude protein level and total body weight gain and protein gain were analysed by broken‐line and second‐order polynomial regression models. Based on total body weight gain, 358.7 g kg^?1 DM dietary protein from good quality sources is recommended for maximum growth of juvenile H. midae, while, if dietary protein is reduced to 280.7 g kg^?1 DM, growth will be depressed with 5 g kg^?1.     

Supplementary oxygen and temperature management during live transportation of greenlip abalone, Haliotis laevigata (Donovan, 1808)

Live greenlip abalone, Haliotis laevigata , are highly valued in Australian export markets with demand increasingly being met with cultured stock. Live transportation of abalone requires the maintenance of favourable conditions within transport containers for periods exceeding 35 h. We examined the combined effects of temperature regulation (ice provision) and of supplemental oxygen (60% and 100% concentrations) on mortality rates of abalone over 7 days following a 35-h simulated live-transport experiment. We also examined the physiological condition of greenlip abalone (oxygen consumption rate, haemolymph pH and weight) during the simulation experiment. The provision of ice and supplementary oxygen reduced abalone mortalities. Omission of ice and supplementary oxygen during the transport simulation resulted in mortality rates ranging from 70% to 100%. The addition of ice to containers with ambient oxygen concentrations decreased average mortality rates by 50%. While supplementary oxygen further reduced these rates, the provision of both ice and 100% oxygen was by far the most effective combination, reducing mortalities to between 2% and 6%. Supplementary oxygen increased oxygen consumption rates of abalone above those transported at ambient oxygen concentrations. Live-transport decreased haemolymph pH in all treatments but was most pronounced in treatments without ice or supplementary oxygen. On average, abalone lost 7–13% of their weight during the simulation but this loss was independent of transport treatment.     

Effect of ammonia on the growth rate and oxygen consumption of juvenile greenlip abalone, Haliotis laevigata Donovan

Juvenile greenlip abalone, Haliotis laevigata, (mean whole weight 4.48±1.9 g, mean±s.d., n=953) were highly sensitive to ammonia as indicated by depressed growth rate and food consumption measured over 2–3 months in bioassay tanks. For growth rate expressed on a whole weight basis, the EC₅ and EC₅₀ values (5 and 50% growth reductions) were 0.041 mg FAN l⁻¹ (Free Ammonia–Nitrogen) and 0.158 mg FAN l⁻¹, respectively. Shell growth rates declined over the entire experimental range (0.006–0.188 mg FAN l⁻¹). At the end of the bioassay, groups of abalone were transferred to respiratory chambers. Oxygen consumption rate increased to a maximum of 188% of control values at 0.235 mg FAN l⁻¹ and decreased slightly at the highest concentration of 0.418 mg FAN l⁻¹.     

Evaluation of an in vitro digestibility technique for the prediction of protein digestibility in the South African abalone, Haliotis midae L.

A pH-stat multienzyme in vitro digestibility assay was investigated for its efficacy in predicting apparent protein digestibility coefficients in abalone diets. Linear regression analysis between in vitro digestibility estimates and in vivo digestibility coefficients obtained from abalone, revealed that the technique could be used to reliably predict apparent protein digestibility. Maximal predictability of the system was obtained when protein sources were analysed according to origin – animal or plant. The technique was used to assess the apparent protein digestibility of 34 potential protein sources for use in formulated feeds for Haliotis midae .     

Triploidy induction in Australian greenlip abalone Haliotis laevigata (Donovan) with cytochalasin B

Triploid induction in Australian greenlip abalone, Haliotis laevigata (Donovan), was conducted by blocking the formation of the second polar body using cytochalasin B (CB). Twenty minutes after fertilization, the zygotes of greenlip abalone were treated with four CB concentrations (0, 0.25, 0.5 and 0.75 mg L⁻¹) for 10, 15 and 20 min. The ploidy of resultant larvae was determined using flow cytometry at 72-h post fertilization. Our study showed that fertilization, hatching, survival and induced triploidy of abalone larvae were significantly affected by the CB concentration and treatment duration. The effective range of CB concentration for triploid induction on greenlip abalone was 0.5–0.75 mg L⁻¹ with an induction duration of 10–15 min. The results indicate that the most effective treatment combination for triploid induction in greenlip abalone is 0.5 mg CB L⁻¹ for 15 min starting at 20-min post fertilization.     

Using micro particle diets to replace diatoms for feeding postlarval abalone Haliotis discus discus (Reeve.)

Feeding artificial micro diets instead of diatoms may allow a more constant and controlled form of nutrition, and thus results in lower mortality rate and increased growth. A 4-week trial was conducted to determine the growth and survival of postlarval Haliotis discus discus (Reeve.) postlarvae fed three experimental micro particle diets, and naturally occurring diatoms. A completely randomized design was adopted with each diet being replicated three times. All diets varied in terms of particle size and gross composition. Survival rate was significantly lower ( P  < 0.05) in the diatom diet (19.5 ± 2.1%) when compared with the K-1 diet (38.8 ± 8.9%), the K-2 diet (43.7 ± 5.6%) and the MD-Q diet (44.2 ± 14.8%). The size of postlarvae fed the four diets was not significantly different ( P  > 0.05). There was also little difference in the daily growth rate. Based on the results of this work for the preliminary implementation of artificial food as a replacement diet for diatoms, it seems that postlarval H . discus discus readily consumes artificial micro particle diets and has a superior survival rate when compared to that of diatoms.     

Survival, growth and osmolality of greenlip abalone Haliotis laevigata (Donovan 1808) when exposed to different ionic profiles of inland saline water

Two experiments over 21 days were conducted to assess the effect of different ionic profiles (mainly K⁺) of inland saline water (ISW) on the survival, growth, osmoregulation and moisture content of juvenile greenlip abalone Haliotis laevigata. In experiment I, the juveniles were cultured in five different water types: ocean water (OW) as a control, inland saline water (ISW or ISW K⁺₀), ISW fortified with 33%, 66% and 100% K⁺ as in OW (ISW K⁺₃₃, ISW K⁺₆₆ and ISW K⁺₁₀₀ respectively). In experiment II, five different culture media, 100% OW(control), 75% OW mixed with 25% ISW (ISW₂₅), 50% OW mixed with 50% ISW (ISW₅₀), 25% OW mixed with 75% ISW (ISW₇₅) and 100% ISW (ISW or ISW₁₀₀), were tested. Within 21 days, all of the abalone in ISW (ISW K⁺₀ and ISW₁₀₀; Na⁺/K⁺ ratio of 111 L^?1) died compared with 100% survival in OW. One‐hundred per cent K⁺ fortification of ISW increased the specific growth rate (SGR) and serum osmolality of the surviving juveniles. The 96 h acute LC₅₀ value was between ISW₅₀ and ISW₇₅. The increased proportion of ISW in OW resulted in significantly (P<0.05) lower survival, SGR and serum osmolality of juveniles. The moisture content of the juveniles was not influenced by any water type. The results suggested that abalone cannot survive in raw ISW, but survival can increase when it is fortified with K⁺ and ionic ratios of ISW are brought closer to OW by mixing it with OW. Furthermore, abalone survival is influenced by other ions in ISW besides K⁺.     

The effects of density on the behaviour and growth of juvenile blacklip abalone (Haliotis rubra)

The growth of juvenile abalone in aquaculture is known to be affected by density as a result of competition for food and decreases in water quality. Our results suggest that behaviour is also affected by density and this also has a significant impact on the growth of individual abalone. 1800 juveniles of Haliotis rubra were individually tagged and reared for 5 months in 12 gravity-fed tanks at two levels of density. The experimental design allowed the differentiation of the direct from the indirect effects of density. The abalone growth and distribution was monitored monthly along with the water quality. The distribution of abalone during daytime was closely related to the availability of preferred shelter space. The percentage of abalone stacked on the top of others increased with density. Preferred shelter space was characterized by low light intensity and a corner or edge for the abalone to rest against. Hides at the ends of the tanks were not occupied as much as others. Abalone were found crawling on the side of the tank during daytime when tanks were shaded. Abalone juveniles of 15–60 mm showed fidelity to their resting shelter during daytime but this fidelity was significantly reduced at the higher density. Shading of the tanks totally changed the distribution of the abalone and their daytime behaviour. Competition for shelter space reduced growth more than water quality. This revised version was published online in August 2006 with corrections to the Cover Date.     

The effect of temperature and conditioning interval on the spawning success of wild-caught blacklip (Haliotis rubra, Leach 1814) and greenlip (H. laevigata, Donovan 1808) abalone

Wild‐caught blacklip (Haliotis rubra, Leach 1814) and greenlip (H. laevigata, Donovan 1808) abalone fed a formulated feed were held at 16 or 18°C for different conditioning intervals ranging from 114 to 235 days and induced to spawn using ultraviolet‐irradiated seawater. They were conditioned again for a second identical period before another induction. For H. rubra, mean spawning rate of both sexes was higher in groups held at 18°C than at 16°C, as was the repeat spawning rate. Conversely, animals held at 16°C produced significantly more gametes than those at 18°C. Egg production peaked in groups held at 16°C for ≥165 days. While both mean and total sperm production of H. rubra varied significantly, both figures were always high. Unlike H. rubra, the spawning rate, repeat spawning rate and gamete production of both sexes of H. laevigata were higher when cultured at 16°C than at 18°C. Egg production peaked in groups conditioned at 16°C for ≥212 days. Both mean and total sperm production by H. laevigata were much lower than for H. rubra. This study demonstrates that year‐round hatchery production of seedstock of both species is possible providing broodstock are held under favourable environmental conditions, preferably 16°C.     

The potential for utilizing fouling macroalgae as feed for abalone Haliotis discus hannai

In order to assess the potential of utilizing fouling macroalgae as feed for abalone Haliotis discus hannai, the species, biomass and total stock of fouling macroalgae attached on the aquaculture facility‐lines were investigated and assessed at Sungo Bay, China, in August 2007. The nutritional value of four fouling macroalgae (Codium fragile, Sargassum muticum, Ulva pertusa and Laminaria japonica) and one cultured macroalgae (Gracilaria lemaneiformis) as the diet of abalone was assessed by analysis of the chemical composition of the macroalgae and by measuring bioavailability and digestibility to abalone H. discus hannai under laboratory conditions in August 2007. The results showed that the biomass of fouling macroalgae at the two sites was 243.61 ± 26.23 and 1078.15 ± 50.28 g m^?1 respectively. The contents of protein of G. lemaneiformis and C. fragile were 18.30% and 17.60%, respectively, which were significantly higher than the others. The five macroalgae were accepted by the abalone, and growth energies (P) and growth efficiency (%) were positive. However, significant differences were found among the different macroalgae. The growth efficiencies of abalone show a negative relationship with the levels of dietary lipid and a positive relationship with the protein contents. These results suggest that fouling macroalgae have a great potential to be used as diets of abalone.     

Growth and biochemical composition of juvenile green abalone Haliotis fulgens fed rehydrated macroalgae

Under controlled laboratory conditions, juvenile green abalone Haliotis fulgens were fed rehydrated natural feeds to determine the effects on growth, survival, feed efficiency and biochemical composition of the digestive gland and muscle. Five macroalgae, Ulva sp. (Chlorophyta), Eisenia arborea, Macrocystis pyrifera, Egregia menziesii (Phaeophyta) and Porphyra perforata (Rhodophyta) were tested. The macroalgae promoted growth, although, depending on the species, there were considerable differences in growth, feed efficiency and biochemical composition of the digestive gland and muscle. Mean growth rate in length and weight and survival rate varied within the ranges 1.6–15.1 μm day^?1, 1.4–8.1 mg day^?1 and 44–69%, respectively. Significantly, higher growth rates were obtained from Egregia menziesii, M. pyrifera and P. perforata. Feed conversion ratio ranged from 6.5 to 42.4 for P. perforata and Ulva sp. Protein, carbohydrates and lipid contents in the digestive gland ranged from 113 to 180, 98.3 to 448 and 17.2 to 23.3 mg g^?1_, respectively. In muscle, the ranges were 66.9–123, 9.5–23.2 and 2.8–3.9 mg g^?1, respectively. This study shows that rehydrated Egregia menziesii, M. pyrifera and, particularly, P. perforata are more efficient in promoting growth than Ulva sp. and E. arborea which match results reported by other authors when using the same fresh macroalgae.     

Temperature and size range for the transport of juvenile donkey's ear abalone Haliotis asinina Linne

Live transport of hatchery‐produced juvenile donkey's ear abalone Haliotis asinina Linne was examined to evaluate the effect of transportation on the survival of juvenile abalone. Simulated transport experiments were conducted to determine the appropriate temperature using 5, 10 and 20 g L^?1 of ice to air volume for 8 h and the appropriate size using two size groups (Size A, 15–20 mm, 0.5–1.3 g, and Size B, 30–35 mm, 5.3–8.5 g) up to 24‐h out‐of‐water live transport. Survival was significantly higher (P<0.001) when 10 g L^?1 of ice was used to decrease the temperature to the range of 17–23 °C. At this temperature, both size groups subjected to simulated transport for 8 and 10 h had 100% survival after 48 h, while mortality occurred in abalones subjected to 16 and 24 h of simulated transport. The Size B abalone subjected to 24 h of transport had significantly higher survival (64.4 ± 2.9%) (P<0.001) than the Size A abalone (5.5 ± 1.6%) after 48 h. Live juvenile abalone were successfully transported to the field applying the protocols developed in the lab experiment. This study serves as a guide for handling and shipping live juvenile abalone.     

Apparent and true availability of amino acids from common feed ingredients for South African abalone (Haliotis midae L.)

Apparent (APD) and true (TPD) protein digestibility and apparent (AAAA) and true (TAAA) amino acid availability of fish meal and plant protein ingredients utilized in the South African animal feed industry (corn gluten meal, soya bean meal, cottonseed meal, sunflower meal, canola meal, peanut meal, lupins and faba beans), incorporated at 450 g kg^?1 into single protein diets, were determined with juvenile South African abalone (Haliotis midae). Soya bean meal (96.34%) and lupins (96.51%) presented the highest APD values, with corn gluten meal (76.08%) the lowest value, while values for sunflower meal (92.21%), canola meal (93.94%) and faba beans (93.17%) were above 90%. APD values for cottonseed meal (86.28%) and peanut meal (86.73%) were comparable with that of fish meal (82.94%). A correlation coefficient (r) of 0.99 was found between ADP and mean AAAA. Furthermore, amino acid availabilities were relatively consistent within various feed ingredients. The mean amino acid secretion from a protein‐free diet was 19.08 mg 100 g^?1 dry diet, resulting in a mean increase of 1.88% units over all feed ingredients when comparing TAAA with AAAA. Calculated APD according to APD coefficients determined with single protein diets underestimated determined APD in several compound diets by 1.10–6.50%, while mean AAAA was underestimated by 6.93%.     

Patterns of growth of juvenile pink abalone Haliotis corrugata fed re-hydrated natural feeds at a laboratory and a hatchery

The feasibility of obtaining a similar growth response from juvenile pink abalone Haliotis corrugata at a research laboratory and a hatchery, when using natural feeds was evaluated. Four macroalgae, Egregia menziesii , Eisenia arborea , Macrocystis pyrifera , Gracilaria sp., and the surfgrass Phyllospadix torreyi were used as feeds. Response patterns of abalone were very similar at both facilities in terms of final length, weight, and survival, varying from 13.0 to 15.50 mm, 0.31 to 0.52 g, and 60.0% to 78.6%, respectively. Better growth was obtained when E. menziesii , M. pyrifera , and Gracilaria sp. were offered. Poor results were obtained with surfgrass. The feed conversion ratio was determined at the laboratory and did not vary significantly, ranging from 42.3 to 199.0; although a significant inverse correlation was observed with growth rate. Growth in length and weight and survival rates varied within 1.6–20.2 μm day⁻¹, 0.123–1.664 mgday⁻¹, 0.4–0.64%day⁻¹, respectively. Mean growth rate in length (14.7μm day⁻¹) and weight (1.18 mg day⁻¹) at the hatchery were significantly higher than that obtained at the laboratory (9.4 μm day⁻¹ and 0.77 mg day⁻¹), which is most likely a consequence of more suitable water temperature at the hatchery. Mean survival rate was significantly higher at the laboratory (53.1%day⁻¹) than at the hatchery (46.1%day⁻¹).     

Dietary phosphorus leaching and apparent phosphorus digestibility from different inorganic phosphorus sources for South African abalone (Haliotis midae L.)

The objective of this study was to determine phosphorus leaching of diets supplemented with various inorganic phosphorus sources [mono basic sodium phosphate (MSP), mono basic calcium phosphate (MCP), a 3 : 1 mixture of mono and dibasic calcium phosphate (MDCP), dibasic calcium phosphate (DCP)], and the apparent phosphorus digestibility of these sources in Haliotis midae. A trend of increased dietary phosphorus leaching from diet pellets with increased water solubility of sources was observed. MSP presented the highest (P < 0.05) phosphorus leaching (58.8%), while a value of 14.9% was obtained with DCP. Unexpectedly high phosphorus leaching (48.7% maximum) was obtained for a reference diet consisting of commercial feed ingredients (fish meal, soya bean meal, cottonseed meal) without any phosphorus supplementation. DCP presented a lower (P < 0.05) apparent phosphorus digestibility (27.9%) than MSP (66.5%), MCP (72.6%) and MDCP (66.3%). When dietary phosphorus leaching and apparent phosphorus digestibility were take into account, MDCP seems to be the most promising inorganic phosphorus source for inclusion in abalone diets. Further research should concentrate on minimizing dietary phosphorus leaching through feed preparation techniques.