Greenlip Abalone Haliotis Laevigata Research Articles

“Fishing Smart”: Bioeconomic Optimization of Fishing Strategies in an Australian Mollusk Fishery

AbstractRecent declines in the biomass of wild abalone populations around Australia are leaving fisheries with low catches, declining profitability, and an uncertain future. Using the abalone fisheries in the western zone of South Australia, we investigate ways to help mitigate these changes by “fishing smart.” We use a two‐pronged approach to demonstrate (1) considerable benefits to fishing abalone during specific months of the year and (2) that fishing profitability can benefit considerably from fleet rationalization. This was achieved by (1) using the seasonally variable biology of abalone to increase fishing efficiency and (2) analyzing the economic benefit of reducing fleet size and fishing season. We demonstrate that profitability can be improved by changing the timing of fishing and amending fleet size as the total allowable commercial catch changes. We show that information on the seasonally variable biology of greenlip abalone Haliotis laevigata and blacklip abalone H. rubra can be used to increase net economic return, reduce exploitation rates, or achieve a combination of these two management objectives. The outputs identify clear economic and biological benefits to altering monthly fishing effort for both species. A cost–benefit analysis contrasted restructure scenarios that involved combinations of changes in fishing season and fleet size with a status quo baseline.

Development of a semi-quantitative scoring protocol for gill lesion assessment in greenlip abalone Haliotis laevigata held at elevated water temperature.

Water temperatures that exceed thermal optimal ranges (~19 to 22°C for greenlip abalone Haliotis laevigata, depending on stock genetics) can be associated with abalone mortalities. We assessed histopathological changes in H. laevigata gills held in control (22°C) or elevated (25°C) water temperature conditions for 47 d by developing a new scoring protocol that incorporates histopathological descriptions and relative score summary. Lesions were allocated to 1 of 3 reaction patterns, (1) epithelial, (2) circulatory or (3) inflammatory, and scored based on their prevalence in gill leaflets. Indices for each reaction pattern were calculated and combined to provide an overall gill index. H. laevigata held in 25°C water temperature had significantly more epithelial lifting and hemolymph channel enlargement and significantly higher gill and circulatory reaction pattern indices than H. laevigata held in 22°C water temperature. One H. laevigata had a proliferation of unidentified cells in the v-shaped skeletal rod of a gill leaflet. The unidentified cells contained enlarged nuclei, a greater nucleus:cytoplasm ratio and, in some cases, mitotic figures. This cell population could represent a region of hematopoiesis in response to hemocyte loss or migration to a lesion. Without thorough diagnostic testing, the origin of these larger cells cannot be confirmed. The new scoring protocol developed will allow the standard quantification of gill lesions for H. laevigata, specifically for heat-related conditions, and could further be adapted for other Haliotis spp.

Development and validation of a SNP-based genotyping tool for pedigree establishment in Australian greenlip abalone Haliotis laevigata Donovan, 1808

To enable cumulative increases in aquaculture productivity, structured and efficient selective breeding programs are required. These are contingent on the management of genetic resources within the breeding population though the attainment of accurate pedigree information which can be provided by DNA-based parentage analysis. This study developed a SNP panel for greenlip abalone, Haliotis laevigata, from DArTSeq data produced from a genetic audit of greenlip abalone (n = 336) from five farms. The initial dataset consisted of 15,320 SNPs. Strict filtering on SNP quality control metrics was conducted to select the most informative 1,004 SNPs for the design of a DArTag™ genotyping panel for greenlip abalone. Sixteen broodstock and 1035 hatchery produced progeny were genotyped using the 1,004 SNP DArTag™ panel. The resulting genotypes were filtered, to produce 705 high performing SNPs. In silico parentage analysis using subsets of these SNPs (highest ranked by polymorphic information content) revealed that the inclusion of < 50 SNPs were satisfactory to resolve parentage for 10,000 simulated progeny to up to 200 candidate parents. The resolving power of the panel was also assessed under high levels of inbreeding (0–50 %) and relatedness (0–50 %) between candidate parents, and conditions of missing parental genotypes (10–50 %) in silico. Under all levels of inbreeding, relatedness and missing parental genotypes simulated, the panel was able to accurately assign parental pairs to the offspring. To validate these in silico results, parentage analysis of the hatchery produced progeny of the 16 candidate broodstock was conducted using both CERVUS and APIS. Complete parentage was assigned to all experimental progeny, with 100 % consensus between the two methods used. This study indicates this panel will serve as an efficient and cost-effective tool for accurate pedigree establishment for greenlip abalone.

Colour change of greenlip abalone (Haliotis laevigata Donovan) fed formulated diets containing graded levels of dried macroalgae meal

This study evaluated the effects of supplementing dried macroalgae meal on the shell, foot and lip colour in terms of colour hue, saturation and brightness and pigment concentration in greenlip abalone Haliotis laevigata. Two species of dried macroalgae meal (Ulva sp. and Gracilaria cliftonii) at four levels (0% basal diet, 5%, 10% and 20%) of dietary inclusion were fed to the abalone (2.89±0.01g; shell length 22.41±0.06mm) for 92days. The abalone fed G. cliftonii meal developed brown-red colour on the shell and the increased inclusion of algal meal resulted in darker brown shells, whereas abalone fed Ulva sp. meal or the basal diet exhibited light green shells. Although foot hue and foot brightness were not influenced by the type and level of inclusion of dried algal meal, the foot colour saturation of abalone fed ≥10% macroalgal meal was significantly higher than those fed the basal diet. Abalone developed a green lip when fed ≥10% of G. cliftonii meal, whereas lip colour did not change when fed Ulva sp. meal inclusion, compared to the basal diet, and exhibited milky lip colour. Although diet pigments varied with the species of macroalgae and inclusion level, β-carotene was the major pigment in the tissue of abalone fed all test diets and its content increased significantly with the inclusion level of macroalgae in the diet. Abalone fed the basal diet had significantly lower tissue β-carotene than those fed the diets with macroalgal inclusion. This study suggests that the inclusion of ≥5% G. cliftonii can produce a brown-red shell and the inclusion of ≥10% G. cliftonii intensifies the green colour of the lip. The brown-red colour mark on the shell by feeding macroalgal meal may be used as a harmless shell-marking method for ranching, stock enhancement or growth study in the wild. Statement of relevanceFeed manipulation can change abalone shell, foot and lip colour.

Colour changes of greenlip abalone (Haliotis laevigata Donovan) fed fresh macroalgae and dried algal supplement

Abalone colour is an important market trait in the seafood industry. Two experiments were conducted over 93days to test the effect of diet on the colour of the foot and shell of 1-year old greenlip abalone Haliotis laevigata. In Experiment 1, a commercial control diet and two species of fresh macroalgae (Gracilaria cliftonii and Ulva sp.) were used and each macroalgae species was either non-enriched or enriched with nutrients in the culture media. The shell of abalone fed the commercial diet and fresh Ulva sp. was green but abalone fed fresh G. cliftonii developed a brown shell. The fresh G. cliftonii increased shell colour purity while fresh Ulva sp. increased shell brightness. Feeding abalone with either fresh Ulva or fresh G. cliftonii produced yellowish foot. Nutrient enrichment of algae did not significantly affect the pigment contents in both macroalgae and abalone, and had minimal impact on the colour of shell and foot. With the exception of zeaxanthin, the pigment contents were significantly lower in fresh G. cliftonii than in fresh Ulva sp. Moreover, β-carotene was the main pigment in abalone fed both species of fresh macroalgae. In Experiment 2, the inclusion of dietary dried algae affected abalone colour. Three diets including a commercial control diet, a diet containing 3% dried Spirulina sp. and a diet containing 10% dried Ulva sp. were used. The shell of abalone fed dried Spirulina sp. was yellow-brown with higher colour purity while the shell remained light green in abalone fed dried Ulva sp. or the commercial control diet. The colour of abalone foot became bright yellow when abalone fed dried Ulva sp. Abalone fed dried algae contained β-carotene as the principal pigment. This study indicates that fresh macroalgae and dried algae supplementation in feed can change the colour of abalone foot and shell. Feed effect on shell colour was far more than on tissue colour. Feeding abalone with fresh G. cliftonii contributes to the formation of brown colour on the shell. Statement of relevanceFeed manipulation can change abalone shell and foot colour.

Restricting feed ration has more effect than diet type on the feeding behaviour of greenlip abalone Haliotis laevigata

Abalone farmed in Australia are predominantly fed formulated feeds, while in the wild, their diet consists of a mix of macroalgae. Here we investigated the feeding behaviour of juvenile greenlip abalone, Haliotis laevigata; fed live macroalgae and formulated diets at different rations; and observed their feeding behaviour using a novel ventral video monitoring technique. Four different diets (commercial chip, experimental flake, Ulva sp. and Gracilaria cliftonii) at two feeding rations (excess vs. restricted) were tested. Diet type had no effect on abalone movement, but macroalgal diets resulted in higher feed intakes. Restricting feed rations induced greater movement. Abalone moved little during the light period and moved mostly during darkness, except for animals on the restricted feed ration where feeding commenced during the light period. On farms, this phenomenon may be a useful behavioural indicator for identifying underfed abalone. Despite their lower intake, formulated diets promoted higher energy and nutritional intake, indicating that quantity of feed consumed is not solely indicative of nutritional gain. From a research perspective, the novel ventral monitoring method has created opportunities for further behavioural studies in molluscs.

Greenlip abalone (Haliotis laevigata Donovan, 1808) sperm cryopreservation using a programmable freezing technique and testing the addition of amino acid and vitamin

This study investigated factors key to the development of sperm cryopreservation in the greenlip abalone Haliotis laevigata using a programmable freezing technique, including (1) permeable cryoprotectant agent (CPA) selection; (2) cooling rate; (3) endpoint temperature; (4) thawing temperature; (5) sperm to egg ratio and (6) sugar, vitamin and amino acid supplementation, using sperm motility, fertilization rate, plasma membrane integrity, mitochondrial membrane potential or acrosome integrity as quality assessment indicators. Results showed that among the permeable CPAs evaluated, 10% dimethyl sulfoxide was the most suitable for greenlip abalone sperm cryopreservation. The highest post-thaw sperm motility was achieved with the sperm being frozen at a cooling rate of 5°C min 1 to 30°C from 0°C and thawed and recovered in 40°C and 18°C seawater baths respectively. The addition of sugars in 10% dimethyl sulfoxide did not significantly improve the post-thaw sperm motility and fertilization rate. The addition of 0.6% glycine, 0.2% taurine or 0.02% L-ascorbic acid, on the other hand, significantly improved the postthaw sperm motility. However, only the addition of 0.6% glycine improved the post-thaw sperm fertilization rate, which was further confirmed by the improvement of the post-thaw sperm mitochondrial membrane potential and acrosome integrity through flow cytometry analysis.

Cryopreservation of sperm in farmed Australian greenlip abalone Haliotis laevigata

This study investigated factors important to the development of the liquid nitrogen (LN) vapor sperm cryopreservation technique in farmed greenlip abalone Haliotis laevigata, including (1) cryoprotectant agent (CPA) toxicity; (2) cooling temperature (height above LN surface); (3) thawing temperature; (4) sperm to egg ratio; and (5) sugar supplementation, using sperm motility, fertilization rate or integrity/potential of sperm components and organelles as quality assessment indicators. Results suggested that among the single CPAs evaluated 6% dimethyl sulfoxide (Me2SO) would be the most suitable for sperm cryopreservation in this species. The highest post-thaw sperm motility was achieved with the sperm that had been exposed to LN vapor for 10min at 5.2cm above the LN surface, thawed and recovered in 60 and 18°C seawater bathes, respectively after at least 2h storage in LN. The highest fertilization rates were achieved at a sperm to egg ratio of 10,000:1 or 15,000:1. Addition of 1% glucose or 2% sucrose produced significantly higher post-thaw sperm motility than 6% Me2SO alone. Among the three cryoprotectant solutions further trialled, 6% Me2SO+1% glucose produced the highest fertilization rate of 83.6±3.7%. Evaluation of sperm has shown that the addition of glucose could significantly improve the sperm plasma membrane integrity and mitochondrial membrane potential. These results demonstrated a positive role of glucose in the improvement of sperm cryopreservation in farmed greenlip abalone.

Comparative Histological Changes in the Greenlip AbaloneHaliotis laevigataGastrointestinal Tract in Response to Water Temperature, Different Dietary Protein Levels, and Animal Age

The land-based culture of greenlip abalone Haliotis laevigata in southeastern Australia is carried out using seawater that is prone to seasonal temperature fluctuations and is done almost exclusively using artificial feeds. Although some nutrition research has been done to identify the optimum dietary protein level, typically farms use only 1 diet for grow-out after the juveniles are weaned. Little consideration has been given to the effects of fluctuating water temperatures and dietary protein levels on the morphology of the gastrointestinal tract (GIT) of abalone. Because these factors are known to impact growth in other aquatic species, it is important that they are investigated further to improve growth in abalone species. In this study, the histological changes of the GIT of greenlip abalone in response to 2 water temperatures and 4 dietary levels of crude protein (juvenile, 27% and 36%; subadult, 24% and 33%) for juveniles (1.75 g) and subadults (22.93 g) were investigated. The epithelial thickness of the stomach and crop; intestinal villus height, width, and area; lamina propria height; and stomach, crop, and intestinal neutral and acidic goblet cell numbers were measured. The stomach epithelium was significantly thicker at 14°C than 22°C in both juveniles and subadults, whereas the crop epithelium was significantly thicker at 22°C than 14°C in juveniles. The crop epithelial thickness of subadults was reduced by increasing dietary protein; however, juveniles did not show the same response. Juvenile abalone were more sensitive to temperature fluctuations than subadults, whereas significant effects of dietary protein levels were only observed in subadults. The alterations in the morphology of the GIT did not appear to be detrimental to the health and growth of the abalone. Further research is required to investigate the interactive effects of water temperature and dietary ingredients, particularly in regard to antinutritional factors, on the morphology and function of the GIT to improve our understanding of abalone physiology.

A snail's pace: A preliminary analysis of the effects of stress and genetics on movement of Haliotis

Aquaculture producers' desire animals that are better able to tolerate and survive stress, but selecting animals with these traits is hampered by a lack of reliable stress indicators in aquatic organisms. Here we undertake a preliminary study to explore behavioural response, in terms of distance travelled, under differing stress histories, in greenlip abalone Haliotis laevigata. Movement trials were performed on labelled abalone of known pedigree relationships by measuring distance and direction travelled in a grid marked slab tank with unidirectional current. Animal and sire models were fitted to the data using a Markov chain Monte Carlo multi trait generalised linear mixed effect model. Distance travelled with respect to water flow was found to be influenced by stress inflicted by sampling tentacles either immediately prior to the movement trial, or inflicted >24hours prior to the trial (P<0.05), while distance travelled from the starting grid (not direction) was significantly affected by stress inflicted >24hours prior to the movement trials (P<0.05), which may be indicative of a delayed or accumulated stress response. There was no evidence that abalone size (length or weight), or the accumulated effects of handling, influenced the distance travelled or direction. The narrow sense heritability of distance and direction travelled was low (0.05 and 0.07 respectively), but significantly greater than zero (95% Bayesian confidence intervals of 0.02–0.16 and 0.03–0.18 respectively), while that of weight and length were moderate to high (>0.4). Parental origin affected distance travelled, such that progeny with parents whose ancestors were selected for faster growth rate for 3 generations, moved longer distances. This difference between animals with different parental origins was exacerbated by stress. The results suggest that behaviour could be a good indicator of some forms of stress.

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+.

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 £ow cytometry at 72-h post fertilization. Our study showed that fertilization, hatching, survival and induced triploidy of abalone larvae were signi¢cantly aiected by the CB concentration and treatment duration. The eiective 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 eiective treatment combination for triploid induction in greenlip abalone is 0.5 mg CB L � 1 for 15 min starting at 20-min post fertilization.

A Growth Assessment of Juvenile Abalone Haliotis laevigata Fed Enriched Macroalgae Ulva rigida

The experiment was conducted to assess the growth of juvenile greenlip abalone Haliotis laevigata fed a range of Ulva rigida diets with different nitrogen contents and an artificial pelleted diet. The minimal nutrient concentration resulting in significant enrichment of U. rigida was 2.25 mg N l−1. The maximum nitrogen content obtained by U. rigida in this study was 6.099%, which resulted from an inorganic nutrient concentration of 7 mg N l−1. However, no further significant increase in enrichment occurred from nutrient concentrations of 10 and 15 mg N l−1. Abalone specific growth rate in shell length (SGRL) and wet weight (SGRW) and foot muscle yield were significantly higher for abalone fed the artificial diet compared to those fed any U. rigida diet. Abalone fed U. rigida enriched in less than 15 mg N l−1 had similar growth rates compared to abalone fed unenriched U. rigida. Abalone fed the artificial diet contributed a higher percentage of weight gain into the valuable foot muscle. The foot muscle moisture content of abalone fed the artificial diet was significantly lower than that of abalone fed any U. rigida diet. The conclusions reached by this study should assist Australian abalone producers in assessing the potential benefits of using U. rigida as an effluent biofilter and subsequent food source for the commercially important juvenile greenlip abalone.

Studies on southern Australian abalone (genus Haliotis) XIII: larval dispersal and recruitment

Adult densities of the greenlip abalone Haliotis laevigata Donovan were manipulated in 24 contiguous 100-m segments of coastline over a distance of 2.4 km. Recruitment at an age of ≈3 months from spawning of the manipulated population was measured in each segment, by using a direct searching technique with an underwater magnifier. Recruitment strength was independent of adult density within the 100-m segments, but varied spatially according to features of coastal topography. Recruitment was highest in inlets and in the lee of submerged pinnacles and lowest on headlands. It is deduced that abalone larvae are transported in near-bottom tidal currents for distances of at least hundreds of metres and are concentrated in places where the bottom and shore topography cause eddies and stagnation zones.