The northern abalone is listed as threatened under the Canadian Species at Risk Act. Northern abalone occur in a wide range of habitats from fairly sheltered bays to exposed coastlines. However, not all habitats are likely to support high abalone densities with large northern abalone that have high fecundity. Therefore, habitats that can support dense concentrations of large abalone would be better suited for aggregation rebuilding projects. Several experimental rebuilding projects are currently underway; the experimental sites were, in general, selected based on abalone presence and relative abundance. This study attempts to describe abalone habitat suitable for rebuilding efforts by using data from surveys completed at the start of the large decline of abalone densities observed in British Columbia (BC). Several areas were surveyed to determine abalone density on the southeast coast of the Queen Charlotte Islands and the north central mainland coast of BC between 1978 and 1980. Habitat data were recorded after each dive, including substrate types and dominant algae cover and species. Four categories of algal types were analyzed based on height and growth patterns: (1) canopy; (2) understorey (large bottom cover); (3) turf (short bottom cover); and (4) encrusting. In addition, an index of wave exposure was also calculated for each site surveyed. Northern abalone density was inversely correlated to mean abalone shell lengths. The exposure index was correlated positively to abalone density but negatively to mean shell length. Regression tree classifications successfully separated habitats of high and low abalone densities, but these differed from habitats classified using mean shell length as the response variable. To optimize rebuilding efforts, a compromise between the two classification models, one with density as the response variable and the other with mean shell length, may have to be developed.

Outplanting abalone seed on artificial reef can potentially achieve the dual aim of stock enhancement and habitat improvement. This study examines the feasibility of ranching with hatchery-reared juvenile Haliotis laevigata Donovan and H. rubra Leach, in northern Port Phillip Bay, Victoria, Australia, and compares growth and survival of outplants on various artificial substrata. The experiments involve seeding 1,440 hatchery-reared juveniles, 10–30 mm size and aged 8–15 mo, at densities of 20–40 m⁻², onto concrete and basalt rock artificial reefs. On concrete artificial reefs, the mean survival of H. laevigata was 15% after two years, with a mean annual growth rate of 39 mm·yr⁻¹. For H. rubra, survival was 9% over three years, and growth rate was 22 mm·yr⁻¹. No significant difference in juvenile survival was detected on noncomplex concrete artificial reef versus complex concrete plus basalt rock habitats. Important lessons for ranching and stock enhancement on artificial reefs are discussed.

The total allowable commercial catch from New Zealand's Haliotis iris Gmelin 1791 fishery was reduced by 18% between 1999 and 2004. Quota holders have initiated research to assess the viability of stock enhancement by release of hatchery-reared seed. Boulder reefs (1 × 2 × 0.5 m) were constructed by placing natural boulders in wire baskets over sand or bedrock. These reefs allowed accurate census of small abalone during short-term experiments (3–4.5 mo.) examining the effects of seed size [5–25 mm shell length (SL)] and density (25–640 m⁻² of seafloor) on survival and growth. Survival increased with seed size, but beyond 10 mm the increased survival did not offset the cost of larger seed. Growth and survival of 8–24 mm seed decreased with increasing density, but regressions were nonsignificant (P = 0.06–0.36) because of variability among reefs. Densities as high as 300 m⁻² gave good growth and survival (>40%) over 3 mo. on some reefs. Five natural sites were seeded with 2,600–20,000 juveniles (mean 10–11 mm SL, range 6–19 mm) at an average density of 50 m⁻² to estimate long-term survival from commercial reseeding. After 17–20 mo, when recovered abalone averaged 47–60 mm SL, survival varied widely among the five sites ranging from 1.7% to 25.1% (average 13.8%). Estimated survival to harvest size of 125 mm SL ranged from 1.3% to 18.6% (average 10.2%) assuming 3 further years of mortality at M = 0.1. The two sites with the lowest survival were affected by substrate movement during storms, highlighting the risk of using exposed locations with boulders small enough to be turned for surveys. Survival to harvest averaged 15.2% across the three sites without significant storm damage. Growth averaged 29.5 mm SL year⁻¹ across the five sites (range 25–33 mm·year⁻¹). A model was used to examine the economic viability of reseeding, assuming that reseeded abalone supplement natural recruits. At a price of NZ$0.32 per 10 mm SL seed, the return on investment was 20% yr⁻¹ at 10% survival to harvest, and 30% yr⁻¹ at 15% survival. These returns compare favorably with opportunity costs of ∼10% yr⁻¹, suggesting that reseeding is likely to be economically viable if sites and habitat are carefully selected. Large scale seeding should be accompanied by monitoring to quantify net population increase.

Abalone aquaculture is rapidly developing in Chile although this mollusc does not occur naturally in this country. The red abalone Haliotis rufescens was introduced in 1977 and the ezo abalone Haliotis discus hannai in 1982. After several years of research and development, the industry began in 1992 and Chile is currently the fifth producer of cultured abalone in the world with 304 tons in 2006. Twenty five companies are involved in this Chilean industry, culturing mainly red abalone. Most of the farms in the North include hatcheries and land-based grow-out operations, whereas most of the in-water grow-out facilities are located in the South. All farms in Chile use algae as the main food for growing abalone, but artificial feeds are also used in some land-based operations in the North. The average size of abalone harvested in Chile is 8 cm (100–120 g) after 3–5 y in culture systems. Whole frozen abalone (shell on) is the most important form of this Chilean product (82% in 2006) and the main market is Japan (90.2%). Abalone production has increased at a rate of around 50% per annum over the last 3 y. This development is expected to continue in the next years, fostered by favorable geographic, economic, and environmental conditions as well as an important government support to invest in abalone. A survey among producers revealed that feed availability and quality is currently considered a key issue to further develop this industry in Chile.

The management section of California's recently adopted Abalone Recovery and Management Plan (ARMP) uses results of fishery independent transect surveys at eight index sites to regulate total allowable catch (TAC) for the recreational red abalone, Haliotis rufescens (Swainson), fishery. The ARMP uses abalone densities over all depths, densities in deep water (8.4–19.7 m), and successful recruitment (>4,500 abalone/hectare in the 100–177 mm size class) to decide whether changes need to be made in the TAC (see ^{Table 1} later). The catch is estimated from telephone surveys and returned abalone permit report cards. Recent surveys in 2003 and 2005 at four of the eight index sites show red abalone densities in the range of the baseline densities established by surveys in 1999 and 2000. Applying the results of the 2003 and 2005 surveys to the ARMP criteria indicates no change is needed in the current TAC. Two-way ANOVA showed there were no significant differences in density between sites (Van Damme and Salt Point; df = 1, F = 0.06, P > 0.8) and time periods (df = 1, F = 1.33, P > 0.25) for all depths combined. Likewise there were no significant differences at deep depths between the two sites (df = 1, F = 0.23, P > 0.63) and the two time periods (df = 1, F = 0.10, P > 0.75).

We estimate annual growth and mortality of red abalone, Haliotis rufescens, in northern California using tag recapture data applied to multiple growth and mortality models. We investigate seven growth models of the form, L _{t 1} = L_t f(L_t ) where L_t is the shell length at tagging (time t), L_{t 1}, is the shell length one year later, and the function f(L_t ) is a model of the change in length ΔL. Abalone are drawn from a broad range of sizes (shell lengths 5–222 mm) tagged and recaptured one year later (n = 231) in the Point Cabrillo Reserve in northern California. We present the results for seven growth models, rank the fit of the models (using the sum of the squared residuals) selecting the Richards, Gaussian, Ricker, and von Bertalanffy models (in that order) as most appropriate for these variable growth data. The von Bertalanffy model yields the shortest time to fishery (recreational legal size is 178 mm) as it slightly overestimates early growth. The Ricker model yields the longest time to enter the fishery underestimating early growth. We present a table of abalone sizes as a function of time for the Gaussian model, from which we estimate the number of years to grow into the fishery (12.0 ± 1 y). Because differences among the applicable models are not great, we use the growth parameters generated by the simple von Bertalanffy model (L_∞ and K) to estimate mortality. The results are consistent among our five mortality estimates ranging from 0.11–0.23 per year. Estimates of the number of years to enter the fishery and mortality estimates, as well as knowledge of how model selection can influence these estimates, is important for fishery management. Informed fishery management for red abalone is critical because the fishery in northern California is the last open abalone fishery in the state.

In most commercial abalone nurseries worldwide, algal biomass grown on vertical plates becomes inadequate once juvenile abalone reach about 5 mm in shell length. At that stage animals need to be moved into a different tank system and weaned onto a formulated feed or alternative algal diets consisting of diatoms or macroalgae that can provide more biomass for the growing juveniles. Two trials were conducted to compare the growth and survival of juvenile greenlip abalone (5.9 ± 0.6 and 7.1 ± 0.1 mm in initial shell length) in two rearing systems: (1) shallower tanks with or without horizontal shelter, feeding a commercial formulated feed on horizontal surfaces; (2) deeper tanks with plate system feeding algal diets. The second experiment included two algal diets and two abalone stocking densities for one of the algal diets. The first experiment revealed that the algal diet consisting of Ulvella lens produced the best growth rates during the first 4 wk of the experiment, when juveniles reached about 9 mm in shell length and seawater temperatures averaged 20.1°C. Growth rates on the Ulvella diet declined rapidly thereafter, whereas growth rates on formulated feeds increased, coinciding with a decrease in seawater temperature to 15.2°C at the end of the experiment. The formulated feed produced high growth rates (over 75 μm day⁻¹) once juveniles reached 7 mm in shell length. In the second experiment, the algal diet that included germlings of the green alga Ulva sp. produced the highest growth rates (105 μm day⁻¹), indicating that Ulva sp. germlings are a suitable additional food source for juvenile greenlip abalone. Growth rates were particularly high towards the end of the experiment when seawater temperatures were above 19°C. Juveniles stocked at higher density (80 juveniles per plate) feeding on one of the algal diets showed reduced growth rates and overall lower average weight gain per individual compared with the juveniles stocked at low density and juveniles in the tank system feeding on formulated diet. In both experiments the survival was higher on the algal diets (77% to 82%) than on the formulated feed (62% to 65%). Culturing and maintaining algae for larger juveniles in the nursery system involved more labor, compared with the tank systems feeding formulated feed, suggesting that in higher labor cost countries, juveniles should be weaned onto a formulated feed as early as possible. We recommend moving animals into a tank system to feed formulated feed once they reach 7 mm in shell length. The weaning process can be delayed (e.g., to 17 mm shell length) by supplementing with macroalgal germlings if the seawater temperature is high and high mortality is expected when weaning onto formulated diets. The algal diet including Ulva sp. germlings produced particularly high growth rates when seawater temperature was above 19°C.

A variety of red algal species have been identified as potential food sources for juvenile Greenlip Abalone, Haliotis laevigata (>5 mm shell length). To provide the red algal species in a diet suitable for juvenile abalone three propagation methods; spore production, protoplast isolation, and fragment culture were investigated. The potential algae requirements and consumable costs for each propagation method were determined, using experimental data and values from the literature, to assess the viability of utilizing each of these propagation methods in a commercial abalone nursery. The use of red algal spores required 592–52,000 kg of algae, depending on the level of spore release and the percentage of fertile algal thalli collected. Protoplast isolation reduced the amount of algal biomass to 8.55–910 kg but was affected by the efficiency of the isolation procedure. Even at an efficient production of 1 × 10⁸ protoplasts·g⁻¹ wet weight alga the cost of consumables (enzymes) was $US 13,576. A feeding trial utilizing Laurencia sp. fragments adhered to the plates using agar, produced juvenile abalone growth rates comparable to those obtained with the current commercial nursery diet of the green alga Ulvella lens plus the diatom Navicula cf. jeffreyi. The Laurencia fragments did not regenerate on the plates so it was reapplied weekly, which is not feasible on a commercial scale because it would require 10.6 t of Laurencia and 443 kg of agar at a cost of $US 34,899. Gracilaria sp. fragments were able to regenerate with a growth rate of 4.42%·day⁻¹ and therefore the algal fragments would only need to be applied to the PVC plates once, at the start of the later nursery phase (5 mm SL), reducing the amount of algal biomass to 432 kg. We therefore conclude that regenerating fragment culture (fragments <1 mm) is the only method that could successfully produce red algal diets for juvenile abalone on a commercial scale in the later nursery phase.

The water bathing postlarval abalone often lies within the diffusive boundary layer (DBL) so its chemistry is greatly influenced by the metabolism of the biofilm on which the abalone feed. This study used microelectrodes to investigate the influence of water velocity and diatom morphology on dissolved oxygen and pH in the DBL. Decreasing water velocity increased the thickness of the DBL, thereby increasing the amplitude of changes in oxygen concentration. Over a film of the prostrate diatom Nitzschia ovalis Arnot, DBL thickness averaged 71, 139, 177, and 406 μm at water velocities of 78, 15, 7, and 1 mm s⁻¹ respectively. Corresponding oxygen concentrations at the biofilm surface under moderate light (75 μE m⁻² s⁻¹) and temperature (15°C) averaged 111%, 120%, 125%, and 151% of air saturation respectively, at the four velocities. The presence of a 1-mm tall diatom canopy (Achnanthes longipes Agardh) over a Nitzschia ovalis film thickened the DBL by 3-fold at 1 mm s⁻¹ and 6-fold at ∼80 mm s⁻¹. The thickened DBL and higher diatom biomass generated extreme conditions at the biofilm surface. Dissolved oxygen concentrations as high as 440% of air saturation, and pH as high as 9.8 were recorded beneath the canopy in moderate light (105 μE m⁻² s⁻¹) and temperature (15°C) at a water velocity of 1 mm s⁻¹. Changes during darkness were less extreme, with 53% oxygen saturation and pH 7.7 the minima recorded. These measurements demonstrate the extreme water chemistry that can develop in the microhabitat of postlarval abalone. The changes will be amplified by the presence of filamentous diatoms, by increased light intensity, and by lack of water movement. Standard aeration will greatly reduce the extremes experienced by postlarvae by generating water movement sufficient to thin the DBL.

A series of trials was conducted to investigate the optimal temperature and light conditions for the culture of 3 benthic diatoms (Cocconeis sublittoralis, Achnanthes longipes and Navicula cf. jeffreyi), their biochemical composition as well as their suitability as a feed source for juvenile greenlip abalone (Haliotis laevigata) (4.07 ± 0.08 mm shell length) in commercial scale nursery culture over 24 wk. C. sublittoralis can grow well in a range of light intensities (830–1,217 lux) and is thus suited for the changing light conditions in a commercial abalone nursery. Achnanthes longipes grows well under high light conditions (1,412–4,400 lux) at low (18°C) and high (25°C) temperatures indicating that this species is more suited to culture in unshaded tanks and higher in the water column, on plates closer to the water surface. Cocconeis sublittoralis and Navicula cf. jeffreyi were cultured together to investigate competitive interactions between the two species. Throughout the experiment Navicula cf. jeffreyi was significantly higher in cell density when grown separately compared with the combined culture with C. sublittoralis. However when considering cell volume C. sublittoralis is substantially larger with a cell volume of 20,183 μm³ compared with 367 μm³ for N. cf. jeffreyi. Thus the cell density of N. cf. jeffreyi must be around 4 times higher than C. sublittoralis to achieve similar biomass, which was only the case at the start of the experiment. Hence N. cf. jeffreyi is a pioneer species (early colonizer) whereas C. sublittoralis is likely to eventually out compete N. cf. jeffreyi. Cocconeis sublittoralis is a suitable diatom species for commercial abalone nurseries, particularly when larger photophobic juveniles ( 5 mm shell length) are cultured and shading is often necessary. The percentage of protein was significantly higher in N. cf. jeffreyi in comparison with the other two species whereas A. longipes contained significantly higher percentage lipid. At a commercial scale juvenile abalone were successfully maintained on diatom diets for at least 18 wk (to ca. 8 mm in SL) after which growth slowed. All diatom species declined in density after week 18 coinciding with a drop in temperature from 20.38 ± 0.09°C at the beginning of the experiment to 16.23 ± 0.11°C. Juveniles feeding on N. cf. jeffreyi and A. longipes reached only 9.99 ± 3.52 and 9.49 ± 3.21 mm, respectively, in nursery tanks after 24 wk. The biomass of these later two species was lowest overall because of the small cell volume of N. cf. jeffreyi and low cell density of A. longipes. Shell length reached 10.71 ± 3.58 and 10.42 ± 3.71 mm in the C. sublittoralis and mixed diatom treatments, respectively. Speci

Feeding activity of the Japanese abalone Haliotis discus hannai is clearly diurnal, with an increase in feeding between the onset of darkness and midnight. The feeding rate increases slowly in the afternoon, approaching sunset and becomes constant between sunset and midnight. The abalone remain within shaded refuges during the day, and only emerge from them at night. The present study evaluated some effects of varying the photoperiod on a group of these abalone to determine its potential effects on their feeding behavior. Three groups of juvenile abalone with an initial mean length near 14 mm were maintained in raceway cage culture systems with a continuous flow of fresh seawater and abundant food where each group was exposed to different photoperiods. Growth of the abalone in these systems was monitored for a period of 106 days. Treatment A, considered “natural,” included 12 h of light and 12 h of darkness. In Treatment B, the abalone were maintained in complete darkness, and Treatment C included four h of light and 20 h of darkness. The results showed that juveniles cultured in total darkness demonstrated some retardation in growth early in the experiment compared with abalone in a natural light regimen, and those with a partial light regimen. After 43 days, the abalone in the partial light regimen reached and surpassed sizes of the abalone maintained in the natural light regimen and in total darkness, although their feeding activity and growth patterns were erratic compared with abalone in the normal light and total darkness regimes. The results of the experiment were inconclusive as to which light regimen was most favorable when considering the growth patterns and comparative mortality rates within the systems.

Growth and survival of the Japanese abalone Haliotis discus hannai were studied over a six-month period at the Center for Abalone Production, Universidad Católica del Norte, Coquimbo, Chile. Cultures were carried out in lantern and basket nets suspended in seawater tanks having a constant flow of fresh seawater from La Herradura Bay. A total of 900 juveniles were observed, starting with individuals having an average length of 20 mm. The abalone juveniles were fed with two species of macroalgae, half of which was Gracilaria chilensis, and the other was half Ulva sp (mass basis), fed ad libitum. Artificial pelletized food was fed as a supplement, at a rate of 2% of the body mass of the abalones daily. Water quality in the cultures was monitored twice daily, included water temperature, pH, dissolved oxygen, and water flow rate. The average survival of the abalones at the termination of the experimental period was 96.2% in the lantern nets, and 94.6% in the culture baskets, although these differences were not statistically significant (P > 0.05; nested ANOVA). The highest mean specific growth rates were obtained in the lantern net systems with rates of 0.34% per day in length and 1.02% per day in weight; comparative values for the basket systems were 0.31% per day and 0.86% per day. Higher growth rates for weight and length of the shell were obtained in the lantern systems than in the basket culture systems. An analysis of covariance of values for growth in weight and length of the abalones showed significant differences between results from the lantern and basket systems (P < 0.05). Based on the results of the study, the lantern systems should be considered as an interesting alternative for the culture of Haliotis discus hannai both in land-based cultures, and at sea, because they have a larger carrying capacity for abalones compared with the baskets in the culture tanks and only occupy one third of the water column space. The lantern nets not only provided the best growth, but were also more economical, and easier to handle than the baskets.

Three closed systems were evaluated for the transport of abalone larvae for use in remote settlement associated with mass culture activities. The first of these systems maintained the larvae in seawater, the second in seawater with oxygen added, and the third in wet condition without seawater but with oxygen added. Survival of the larvae was determined within each system over periods of 10, 16, and 36 h. In a separate experiment, larval settlement in aquaria was determined after holding the larvae in the three different transport systems for 10 h. The results showed the best survival was obtained for the larvae in water alone, with survival rates ranging from 97% at 10 h to 63% at 36 h. In the system without water these rates were 88–50% respectively. The use of oxygen in the transport systems only produced a positive effect at 36 h. Larval settlement after 10 h showed no significant differences in relation to transport system, from 60% settlement of larvae transported in water to 54% settlement of larvae in the wet condition, not suspended water.

Metamorphosis induction and postlarval growth of the red abalone (Haliotis rufescens) were evaluated in a commercial farm of Baja California, México. This hatchery settles larvae with gamma-aminobutyric acid (GABA, 1-μM final concentration) and culture postlarvae in 250-L tanks placed in a four-story structure inside a building with artificial illumination. Eight tanks (four at the top and four at the bottom of a culture structure) were sampled during four months after settlement. Upper tanks received more light than the lower tanks (means of 727 and 217 lux, respectively) and had a higher mean water temperature (14.9°C and 14.4°C, respectively). Estimates of metamorphosis induction were highly variable (37% to 99%) and mean values were higher in lower (76%) than in higher (54%) tanks. Potential causes of this unexpected variability are discussed. There was a significant positive linear relationship between metamorphosis induction and early (7-day) postlarval survival. Average postlarval growth rates were also highly variable among tanks (37–63 μm/day) and slightly higher in upper than in lower tanks (60 and 52 μm/day, respectively). During the sampling period, growth variability was positively associated with water temperature changes, especially after the formation of the first respiratory pore when growth increased abruptly.

The effect of two light conditions (light at 10–13-μmol quanta/m²/s and darkness) in three water flow rates (0, 200, and 600 mL/min) on the survival, grazing, and growth rates of 6-day-old Haliotis rufescens postlarvae (pl) was evaluated. A factorial experiment with three replicates per treatment in blocks was conducted for 44 days in 2-L plastic containers with ca. 100 postlarvae each, inoculated every week with the cultured diatom Navicula incerta. Survival was highest (80%) in the treatment without water flow and with light, whereas the lowest (52%) corresponded to the 600-mL/min flow rate under darkness, but these differences were not significant. Initial grazing rate was significantly higher in darkness than in light (37 cell/pl/hr, SE = 1.6, and 27 cell/pl/hr, SE = 2.8, respectively). Growth rate was not significantly affected by the light treatments. However, in static conditions growth was higher in darkness (38-μm/day, SE = 2.0) than in light (34-μm/day, SE = 1.0). Growth rates of postlarvae were significantly affected by flow conditions, with means of 36 (SE = 1.3), 33 (SE = 0.7) and 31 (SE = 0.7) μm/day in flows of 0, 200, and 600 mL/min, respectively). These results suggest that the benefits of dark conditions on the growth rate of abalone postlarvae shown in previous experiments might not occur under flow conditions. However, the flow rates tested here were apparently too high to allow an optimal postlarval growth and slower flows should be tested in future experiments. On the other hand, flow allowed the development of high diatom densities under the light condition, which were difficult to maintain in darkness.

The effects of chloramphenicol and streptomycin/penicillin on the concentration of heterotrophic bacteria in biofilms associated with abalone postlarval culture and on the growth and survival of Haliotis rufescens postlarvae (3–5 days old) were studied under laboratory conditions. Two experiments were carried out in 12-well polystyrene tissue culture plates with 5 mL of 1-μm-filtered autoclaved seawater. Water was changed every other day and antibiotics were added during the water change. Experimental units were previously inoculated with the benthic diatom Navicula incerta. In the first experiment chloramphenicol at 0, 5, 10, and 20 mg L⁻¹ was used and a mixture of streptomycin and penicillin at 0/0, 50/50, 100/100, and 150/150 mg L⁻¹ was tested in the second experiment (in both cases with three replicates). Bacterial counts (Zobell plates) were performed for a period of 4 and 5 wk (experiments 1 and 2, respectively). Bacterial densities decreased 90% in 20 mg L⁻¹ of chloramphenicol during the first 48 h; however, bacterial counts increased in all treatments thereafter and differences were not significant at the end of the experiment. The growth of abalone postlarvae was not significantly different among treatments. In the experiment with antibiotic mixtures, bacterial abundance was reduced 99% at the highest concentration (150/150) in the first 48 h, and remained significantly lower than the control for 2–3 wk. During this period, postlarval growth in this antibiotic treatment was also slower, as well as final survival, suggesting an important role of bacteria in the nutrition and/or digestion of abalone postlarvae. Results of this study also suggest that bacterial resistance to these antibiotics develops fast, discouraging their long-term use in abalone culture.

Traditional abalone culture is carried out in flow-through systems with water exchange rates between 200 and 2,400% of the total tank volume per day. These high volumes of water associated with abalone culture represents a constraint for the growth of this industry, and recirculating systems can become a viable alternative, because the water exchange rates are less than 10% of the total volume. The objective of this experiment was to evaluate the water quality parameters and the growth rate and mortality of the pink abalone cultured at two different densities, 10% (D1) and 30% (D2) in a flow-through system (S1) and two closed recirculating systems (S2 and S3). A total of 2,400 juvenile abalone (7.11 ± 2.0 g and 37.01 ± 3.4 mm) were distributed among the three experimental systems. The experiment lasted for 127 days. Weight and length of all the abalone were measured at the beginning and end of the experiment. Average water quality parameters for each system (S1, S2, and S3) were respectively: temperature (18.2 ± 1.4, 18.4 ± 1.9, and 18.1 ± 2.0°C); salinity (33.8 ± 1.0, 34.5 ± 1.2, and 34.2 ± 1.5‰); alkalinity (127 ± 13.2, 135 ± 13.7 and 131 ± 14.1 mg of CaCO₃/L), total ammonia nitrogen (0.006 ± 0.02, 0.03 ± 0.07, and 0.02 ± 0.08 mg TAN/L) and nitrite (0 ± 0.00, 0.08 ± 0.07, and 0.07 ± 0.05 mg NO₂/L). Growth rates in weight (g/d) were for S1D1 (0.027 ± 0.007), S1D2 (0.018 ± 0.001), S2D1 (0.007 ± 0.001), S2D3 (0.005 ± 0.000), S3D1 (0.007 ± 0.000) and S3S2 (0.009 ± 0.003), and growth rates in length (mm/d) were for S1D1 (0.038 ± 0.004), S1D2 (0.031 ± 0.002), S2D1 (0.013 ± 0.001), S2D3 (0.013 ± 0.000), S3D1 (0.002 ± 0.000), and S3D2 (0.024 ± 0.001) respectively. In flow through systems growth in length and width was density dependent. Mortality was higher in S3D2 than in any other treatment. A lower water exchange rate in closed systems could adversely affect growth and mortality. Abalone culture in closed recirculating systems could become another alternative for this industry, but more research is required.

A 240-day feeding trial was conducted in a recirculated water system to investigate the effects of dietary vitamin E on the activities of antioxidant enzymes (catalase, CAT; superoxide dismutase, SOD; glutathione peroxidase, GPX) and the composition of fatty acids in abalone, Haliotis discus hannai Ino. Triplicate groups of juvenile abalone (initial weight: 0.71 ± 0.00 g; initial shell length: 15.49 ± 0.04 mm) were fed to satiation one of three semipurified diets containing 0, 50, and 5,000-mg/kg vitamin E, respectively. Abalone were sampled on the 120th day and the 240th day, respectively. There were no significant differences in activities of CAT and SOD in soft body of abalone fed with different levels of dietary vitamin E for 120 days (P > 0.05), but significantly higher activity of GPX was found with 5,000-mg/kg dietary vitamin E (P < 0.05). Activities of CAT and GPX were significantly elevated by dietary vitamin E on the 240th day. The lowest value of 18:1n-9, 18:2n-6 and the highest value of 22:6n-3 in soft body were found with 50 mg/kg dietary vitamin E supplement on the 120th day. On the 240th day, the content of monounsaturated fatty acids (MUFA) in abalone with 50-mg/kg dietary vitamin E supplement was significantly higher than those in the other two treatments (P < 0.05). There were no significant effects of dietary vitamin E on the content of polyunsaturated fatty acids (PUFA) in abalone during the two sampling periods (P > 0.05). In conclusion, 50-mg/kg dietary vitamin E supplement elevated the activities of antioxidant enzymes and could protect MUFA from peroxidation damage. Excessive dietary vitamin E (5,000 mg/kg) did not serve as an antioxidant any more, but tended to be a pro-oxidant in the soft body of abalone.

Juvenile abalone, Haliotis discus hannai Ino (initial mean body weight: 0.56 ± 0.01 g, shell length: 15.74 ± 0.13 mm) were fed six diets with graded levels of pyridoxine (PN) (0.40, 12.5, 22.7, 43.5, 87.8, and 172.2 mg/kg diet). Each diet was fed to three replicate groups of juvenile abalone for 16 wk. Dietary PN significantly (P < 0.05) affected abalone growth, tissue concentrations of PN and pyridoxal 5′-phosphate (PLP), and the activities of asparatate aminotransferase (AST) and alanine aminotransferase (ALT). The responses of all these parameters to dietary pyridoxine levels fitted the broken-line model. Broken-line regression analyses showed that the breakpoints were 23 on the basis of growth data, 32–38 on tissue concentrations of PN and PLP, 20–21 on the activities of visceral AST and ALT, and 39–40 on the activities of muscle AST and ALT. Hence, the requirement of H. discus hannai for dietary pyridoxine should be 23 mg/kg diet for maximum growth, and about 40 mg/kg diet for the saturation of tissue PN and PLP, or tissue aminotransferase activities.

Greenlip abalone (Haliotis laevigata) (Donovan 1808) is a preferred aquaculture species in temperate Australia and selective breeding programs are being developed for this species. This study presents the results of a genetic parameter study for a small population grown on a farm in Tasmania, Australia. A total of 21 families were produced from 14 parents, with all parents except one being used in at least two families. Length and total weight were measured at four periods during the grow-out (10, 21, 27, and 38 mo after spawning) and at the final assessment meat and shell weights were also assessed. Because of issues with tag durability, only 17 of the original 21 families were recovered at final assessment. Genetic variation was low and, at best, the age 3 y heritabilities for total weight, meat weight, and length were 0.10, 0.10, and 0.04 respectively. Despite this low genetic variation, economically important gains appear possible in this small population, with a 5% gain in total weight being predicted. Prior to age 2.5 y, the genetic variation for length and weight appeared to be masked by maternal, larval, and settlement effects. The main factors limiting genetic gains in this study were difficulties in raising large numbers of pedigreed families in separate larval and settlement tanks, the effects of variability in the stages up to and including settlement and difficulties in tagging animals. DNA pedigree assignment is seen as a way to overcome these limitations.

The fundamental goal in cytogenetics is to analyze how the structure and behavior of chromosomes guarantee the conservation of the genetic information throughout the process of inheritance, and how the chromosomal variations could affect the evolutionary process. The aim of this study is to ascertain the cytogenetical relationships of three abalone species from California. Larval cells were obtained from Haliotis corrugata, H. fulgens, and H. rufescens to obtain metaphase chromosomes. Karyotype analysis showed that all studied species have a diploid number of 2 n = 36 chromosomes. However, the relationship of chromosomal arms lengths showed that H. rufescens has 8M 9SM 1ST (metacentric submetacentric subtelocentric) chromosome pairs, H. fulgens has 8M 8SM 2ST, and H. corrugata has 10M 7SM 1ST. Statistical analyses carried out on abalone chromosomal morphology showed that from the 18 chromosome pairs of each species, 8 pairs were similar in all three species; 3 pairs were specific to H. rufescens, 7 pairs to H. fulgens, and 2 pairs to H. corrugata. Chromosome relationships showed that H. rufescens and H. corrugata are cytogenetically more similar to each other than either is with respect to H. fulgens. We suggest that significant chromosomal rearrangements occurred during the evolution of Haliotidae on the California coast. The implications of the karyological composition of California abalone and their genome sizes are discussed.

Pacific abalone (Haliotis discus hannai) and Californian red abalone (Haliotis rufescens) are easily distinguished by their shell and epipodial characteristics. A few individuals of H. rufescens were discovered to have epipodial coloration similar to that of H. discus hannai suggesting that they may have been hybrids of the two species, because hybridization of these species has been informally reported from local hatcheries. The present study uses molecular genetic methods to determine whether the rarely colored variants represented hybrids between the two species. Two hundred RAPD primers were tested with PCR on two DNA pools of eight individuals of each species. Primers that showed different amplification profiles between species were tested on 27 randomly sampled individuals of each species to check the existence of polymorphisms. Two primers differentiate both species. Primer 356 amplified an approximately 450 bp and 460 bp specifics-DNA fragments in H. discus hannai that were not present in red abalone, whereas primer 368 amplified a 750 bp, 850 bp, 860 bp, and 1,190 bp specific-DNA fragments in H. rufescens that were not present in H. discus hannai. The amplification pattern of the DNA of individuals with ambiguous morphology for both primers was characteristic of red abalone. The results strongly suggested that the specimens with unusual epipodial coloration were not hybrids, but rather, phenotypic variants of H. rufescens. Future studies should focus on the cause of the variation of epipodium color in H. rufescens, which could be either genetic polymorphism or phenotypic plasticity.

The design of appropriate management plans of the green abalone Haliotis fulgens fishery needs a better understanding of the present status of the genetic diversity of the wild stock, as well as its genetic structure. Samples from nine locations along the Baja California Peninsula, including one from an oceanic island (Isla Guadalupe), were obtained covering the areas where the commercial fishery is active. DNA was extracted from muscle tissue of 50 individuals from each location, and was used for PCR amplification of 4 microsatellites (Hka28, Hka56, Hful260, and Hful603). The number of alleles observed in all samples with Hka28 and Hka56 (23–35 and 15–19, respectively) was higher than that observed in Hful260, and Hful603 (3 and 6 alleles, respectively). A relatively high mean heterozygosity was observed in all locations with the lowest value of 0.687 in Isla Guadalupe. A deviation from Hardy-Weinberg Equilibrium (HWE) caused by a heterozygote deficiency was only observed in 2 out of 36 tests, indicating that this disequilibrium is random. An AMOVA showed a significant F_ST (P < 0.00196) suggesting genetic differentiation among locations. Pairwise analyses using F_ST and allele frequencies showed that the significant difference was caused by Isla Guadalupe, which indicates a restricted gene flow between this and the other locations. Nevertheless, no significant differences were observed among sites along the Peninsula. The implications of these results on the management of the fishery are discussed.

First description of the complete embryo and larval development of the Canarian abalone (Haliotis tuberculata coccinea Reeve.) was conducted along 39 stages from fertilization to the appearance of the third tubule on the cephalic tentacles and illustrated in a microphotographic sequence. Eggs obtained by induced spawning with hydrogen peroxide from the GIA captive broodstock were stocked at a density of 10 eggs/mL and kept at 23 ± 0.5°C for 62 h until the formation of the third tubule. Live eggs and larvae were continuously observed on a 24 h basis at a ×400 magnification under transmitted light. At each stages, specific morphological features, illustrated by microscopic photographs, were described, as well as the time required for their apparition. Fertilized eggs diameter was 205 ± 8 μm (mean ± SD), whereas length and width of larvae ready to undergo metamorphosis were 216.6 ± 5.3 μm and 172 ± 8.8 μm, respectively. Knowledge on the larval morphological development acquired through this study will contribute to the improvement of larval rearing techniques for this abalone species.

This is the first time that the genus Dodecaceria is reported in shell galleries of the red abalone Haliotis rufescens. The worms measures up to 60-mm long with about 120 setigers and have a brown-greenish color. Previously Rozbaczylo and Carrasco (1996) mentioned the presence of this species in the shells of the gastropod molluscs Fissurella maxima and Concholepas concholepas and in the bivalve Aulacomya ater. Hernández et al. (2001) reported it in the shell of the barnacle Austromegabalanus psittacus in Concepción, Chile.

Various red abalone shells (Haliotis rufescens) taken from Chiloé, X Region, Chile, were examined revealing an enormous amount of vermiform organisms identified as phoronides (Phylum Phoronida) belonging to the genus Phoronis. These individuals have an extended vermiform body not divided into segments, but its upper extreme shows a crown of tentacles shaped in a circular ring (that is the reason why they could be confused with Sabellidae polychaetes, although they do not have segmented body and lack bristles). These are found in the interior of very fragile quitinous tubes. Only Phoronis ovalis has been recorded in Chile found perforating the shell of Chilean abalone, Concholepas concholepas, in samples from the coastal rocks of Mehuin, Valdivia (Arenas 1972).

The external morphology of sabellids polychaetes gathered from green abalone (H. discus hannai) and 2 species of Chilean native gastropods (Fissurella sp. and Concholepas concholepas) was studied. According to the taxonomic keys of Fauchald (1977) and Rozbaczylo (1980), all of these polychaetes belong to the family Sabellidae; subfamily Fabriciinae, and genus Oriopsis (according to Day 1967 and Fitzhugh 1989). This work constitutes the first report of the presence of sabellids of the genus Oriopsis forming tubes in the shell of the green abalone Haliotis discus hannai. The worms analyzed correspond to small sized sabellids (1–2 mm long). The body is fusiform, not sacciform like T. heterouncinata. The gill crown is constituted of three pairs of radiolae, unlike T. heterouncinata counting with 2 pairs of radiolae. Another important difference with this sabellid previously reported habiting abalone shells is the shape of the abdominal uncini, in Oriopsis are rasp-shaped plates, without main fang, defining a clear difference with the abdominal uncini acicular with a single main tooth crowned with shorter series of teeth, characteristic of T. heterouncinata.

The sabellid polychaete Terebrasabella heterouncinata (Fitzhugh & Rouse 1999) has a unique life history in which larvae settle on the edge of gastropod shells and rely on shell deposition to create a tube with an opening to the exterior. This worm was accidentally imported to California, USA on abalone from South Africa in the 1980s and spread with abalone shipments to most culture facilities and some public aquaria throughout the state. Its ability to infest California's native gastropods has sparked concern regarding potential establishment in intertidal habitats adjacent to facilities that held sabellid-positive abalone. We examined the ability of T. heterouncinata to transmit between individual turban snails, Tegula funebralis. We found that transmission between T. funebralis did occur, but at a significantly slower rate than that between red abalone Haliotis rufescens. During 2002 to 2006 native gastropods (turban snails and limpets) were collected at most sabellid-exposed sites and no T. heterouncinata were detected; it thus appears that this species has not become established in California. Freshwater exposure was examined as a method to kill T. heterouncinata in shell fragments that may remain after abalone are removed from production or display units. Freshwater immersion for up to 8 hours but not 16 or 32 h resulted in survival of adults and/or larvae resident in brood chambers. In a similar study, motile T. heterouncinata larvae were found to survive up to 32 sec of freshwater exposure, whereas none survived a 64-sec exposure. These data can be used by abalone culture and display facilities to establish reliable sanitization procedures to prevent T. heterouncinata transmission or reinfestation.

Research and captive rearing programs targeted to restore the endangered white abalone, Haliotis sorensen, are being conducted in California and Washington state. Captive rearing, whereas successful, has demonstrated that this species is highly susceptible to withering syndrome (WS), a rickettsial disease of abalone; WS has not been demonstrated in remnant wild white abalone populations. Thus, WS may limit white abalone production and supplementation of captive abalone must include measures to preclude the introduction of WS into wild populations. Oxytetracycline (OTC) is approved for use in aquaculture and has been demonstrated to effectively reduce rickettsial loads, WS development, and associated losses. White abalone were medicated at 90.82 mg/kg of OTC daily for 20 days and the efficacy, elimination, and potential to protect against exposure to the WS rickettsia were examined. This study illustrated that OTC effectively eliminates rickettsial infections. High concentrations of OTC (1,089 ppm) were observed in the digestive gland after medication; depletion occurred over a prolonged period providing protection to rickettsial challenge in abalone with a mean of over 72 ppm in this tissue. These data highlight the need for further optimization of this drug for use in commercial and restoration aquaculture.

Mollusc shell formation requires calcium (Ca ) and bicarbonate (CO₃ ⁻) ions, transported through the mantle via the hemolymph, and the secretion of an organic matrix that interacts with the mineral ions to form either the aragonite or calcite polymorph of calcium carbonate (CaCO₃). The biomineralization process takes place in the extrapallial space, between inner shell and outer mantle epithelium, and is believed to be under the control of calcium-binding proteins and hormonal factors such as calcitonin-related molecules (CGRP-like peptides). Epithelial cells from the mantle are responsible from the secretion of matrix molecules whereas hemocytes are involved in ion transportation during shell formation and regeneration. To understand the biochemical and cellular events implied in the biomineralization process, we developed primary cell cultures from the nacreous gastropod Haliotis tuberculata. Mantle cells as well as hemocyte cell cultures were successfully maintained in vitro and evaluated for their viability and proliferation using semiautomated assays. The effect of calcitonin-related molecules (h-CGRP) on cellular activity and proliferation was evaluated in those primary cell cultures. The results indicate that human-CGRP modulates the activity of both mantle cells and hemocytes and increases carbonic anhydrase activity in vitro. These results are consistent with those obtained in vivo, supporting the hypothesis that CGRP-like molecules control the activity of target cells involved in the biomineralization process.