Zealand Abalone Research Articles

Re-assessment of a blackfoot abalone (Haliotis iris) population in Peraki Bay, New Zealand, after 45 years

ABSTRACT Marine species are facing an increasing number of stressors and some species once thought to be resilient to change are now threatened. It is important to understand how species populations have changed through time so that management can be adjusted accordingly, and so that achievable restoration goals can be set. However, many species lack population data at multidecadal or longer time scales. Using historical data from the 1970s, this study investigates how the dynamics of a New Zealand abalone (Haliotis iris), or pāua, population at Peraki Bay changed over a 45-year period. No commercial fishing of the population occurred prior to the initial survey and limited commercial catch has been reported between surveys. Repeat monitoring of the H. iris population at a 45-year interval indicates that a large change in population size and structure had occurred. Since 1976, there has been an 84% decrease in estimated population size. The remaining population is restricted to where juveniles were found in the original survey. These findings are consistent with conclusions, made from modelling in the 1970s, that the population seen in the 1970s was not stable and that a possible cause was temporal variability in population recruitment.

Allocations, quota and abalone fishery management: the Tragedy of the commons revisited

ABSTRACT Fisheries management uses a variety of methods to assess stocks, assign quota or allocations, and calculate potential for sustainability. In the New Zealand abalone (pāua) fishery, neither the total stocks nor amount removed in any fishing year are well-known because a major portion is fished ‘recreationally’, for which there is no requirement for a licence or catch reporting. Actual harvests relative to allocations cannot be established until well after the fishing season, and require data not typically collected. This was demonstrated over a 3-month fishing season opened after a 5-year closure along the earthquake-affected northeastern coast of the South Island. Recreational fishers removed c.74% of nearshore biomass of Haliotis iris populations. This was, in effect, a Tragedy of the Commons, whereby a common resource is exploited by those who harvest first, with scant regard for what remains. The underlying weakness is in the recreational fishing management rules which, in this instance, provide stark lessons in why abalone populations have come under pressure worldwide. We discuss concepts, prior knowledge, inertia in management, and a potential way forward, with the aim of preventing serial depletion of pāua populations and fostering more effective management that ends the Tragedy of the Commons.

Application of palaeogenetic techniques to historic mollusc shells reveals phylogeographic structure in a New Zealand abalone.

Natural history collections worldwide contain a plethora of mollusc shells. Recent studies have detailed the sequencing of DNA extracted from shells up to thousands of years old and from various taphonomic and preservational contexts. However, previous approaches have largely addressed methodological rather than evolutionary research questions. Here, we report the generation of DNA sequence data from mollusc shells using such techniques, applied to Haliotis virginea Gmelin, 1791, a New Zealand abalone, in which morphological variation has led to the recognition of several forms and subspecies. We successfully recovered near-complete mitogenomes from 22 specimens including 12 dry-preserved shells up to 60 years old. We used a combination of palaeogenetic techniques that have not previously been applied to shell, including DNA extraction optimized for ultra-short fragments and hybridization-capture of single-stranded DNA libraries. Phylogenetic analyses revealed three major, well-supported clades comprising samples from: (1) The Three Kings Islands; (2) the Auckland, Chatham and Antipodes Islands; and (3) mainland New Zealand and Campbell Island. This phylogeographic structure does not correspond to the currently recognized forms. Critically, our nonreliance on freshly collected or ethanol-preserved samples enabled inclusion of topotypes of all recognized subspecies as well as additional difficult-to-sample populations. Broader application of these comparatively cost-effective and reliable methods to modern, historical, archaeological and palaeontological shell samples has the potential to revolutionize invertebrate genetic research.

The Effects of Live Transport on Metabolism and Stress Responses of Abalone (Haliotis iris).

The New Zealand abalone industry relies mostly on the export of processed products to distant Asian markets, notably China. Over the past five years, live export of high quality abalone from New Zealand has proven successful. However, transport of live animals is associated with multiple stressors that affect survival and meat quality at the end of the transport phase. Better understanding of transport-derived stress is needed to improve transport conditions and recovery at destination to ensure high product quality and safety throughout the supply chain. To this end, we applied an untargeted GC–MS-based metabolomics approach to examine the changes in metabolite profiles of abalone after a 2-day transport event and subsequent water re-immersion for 2 days. The results revealed alterations of many metabolites in the haemolymph and muscle of post-transported abalone. Decreased concentrations of many amino acids suggest high energy demands for metabolism and stress responses of transported abalone, while increases of other amino acids may indicate active osmoregulation and/or protein degradation due to oxidative stress and apoptosis. The accumulation of citric acid cycle intermediates and anaerobic end-products are suggestive of hypoxia stress and a shift from aerobic to anaerobic metabolism (resulting from aerial exposure). Interestingly, some features in the metabolite profile of reimmersed abalone resembled those of pre-transported individuals, suggesting progressive recovery after reimmersion in water. Evidence of recovery was observed in the reduction of some stress biomarkers (e.g., lactic acid, succinic acid) following reimmersion. This study revealed insights into the metabolic responses to transport stress in abalone and highlights the importance of reimmersion practices in the supply chain of live animal exports.

Effects of Ultrasound Treatments on Tenderness and In Vitro Protein Digestibility of New Zealand Abalone, Haliotis iris.

Canned pāua, Haliotis iris, is a premium New Zealand product that is exported to Asia. The objective of this research was to investigate the effects of ultrasound treatments on pāua texture, microstructure and in vitro protein digestibility. Whole pāua meat was ultrasound-treated (20 kHz, 464 ± 9 W) for 5 min in water (with or without subsequent soaking in water at 4 °C for 24 h) or ultrasound-treated in 1% actinidin enzyme solution. Post-treatment cooking of canned pāua was done in a water retort at 116 °C for 30 min. All ultrasound-treated cooked pāua yielded lower slice shear force values (SSFV) than untreated canned and cooked samples. The lowest SSFV was attained when ultrasound treatment in water was followed by soaking at 4 °C for 24 h. The increased tenderness of ultrasound-treated pāua could be linked to disintegration of myofibers and formation of gaps between myofibers, as observed through histological analysis and transmission electron microscopy. Collagenous fragmentation was also observed, particularly in pāua ultrasonicated in enzyme solution. Raw pāua was found to be more digestible in terms of free amino N released during in vitro digestion than all cooked samples. However, cooked ultrasound pre-treated pāua was more digestible than the control cooked sample.

Immune response in probiotic-fed New Zealand black-footed abalone (Haliotis iris) under Vibrio splendidus challenge

Vibriosis disease is a major constraint for sustainable molluscan aquaculture. Development of strategies to enhance disease resistance during grow out would greatly reduce stock mortality and boost production yields. In this study, New Zealand black-footed abalone (Haliotis iris) were fed a commercial diet enhanced with multi-strain probiotics (Exiguobacterium JHEb1, Vibrio JH1 and Enterococcus JHLDc) for four months, then challenged with an injection of pathogenic Vibrio splendidus. Host immune responses in haemocytes were characterized using flow cytometry by measuring total haemocyte counts (THC) and viability, degree of apoptosis, and production of reactive oxygen species (ROS) 48 h post-challenge. Probiotic-fed abalone had significantly higher survival rates compared to control animals after the bacterial challenge. Infected probiotic-fed abalone also had significantly higher haemocyte viabilities, slightly lower proportions of haemocytes undergoing early apoptosis, and lower proportions of ROS-producing haemocytes compared to infected control-fed abalone. In addition, metabolite profiles of muscle tissues generated via gas chromatography–mass spectrometry (GC-MS) delivered complimentary evidence to support a perturbed ROS-regulatory system in infected abalone through changes in key metabolites associated with glutathione biosynthesis. The results of this study provide valuable information to assist in farm management practices, leading to enhance production and sustainability of the New Zealand abalone aquaculture industry.

Ocean acidification induces carry-over effects on the larval settlement of the New Zealand abalone, Haliotis iris

Abstract Larval settlement is a key process in the lifecycle of benthic marine organisms; however, little is known on how it could change in reduced seawater pH and carbonate saturation states under future ocean acidification (OA). This is important, as settlement ensures species occur in optimal environments and, for commercially important species such as abalone, reduced settlement could decrease future population success. We investigated how OA could affect settlement success in the New Zealand abalone Haliotis iris by examining: (1) direct effects of seawater at ambient (pHT 8.05) and reduced pHT (7.65) at the time of settlement, (2) indirect effects of settlement substrates (crustose coralline algae, CCA) preconditioned at ambient and reduced pHT for 171 days, and (3) carry-over effects, by examining settlement in larvae reared to competency at ambient and reduced pHT (7.80). We found no effects of seawater pH or CCA incubation on larval settlement success. OA-induced carry-over effects were evident, with lower settlement in larvae reared at reduced pH. Understanding the mechanisms behind these responses is key to fully comprehend the extent to which OA will affect marine organisms and the industries that rely on them.

Physicochemical changes in New Zealand abalone (Haliotis iris) with pulsed electric field (PEF) processing and heat treatments

The effects of pulsed electric field (PEF) processing (0.66, 1.38 and 2.00 kV/cm, 50 Hz) with and without heat treatments (70, 80 and 90 °C for 15 min) on color, texture profile, lipid oxidation value, free amino acids (FFAs) and fatty acids (FAs) content of abalone muscle were studied. PEF treatments had less effects on the physical and chemical characteristics of heated and non-heated samples. Heat treatments however significantly changed meat color, as well as increased toughness and elasticity. In addition, lipid oxidation, and free amino acids (FAAs), and saturated fatty acids (SFAs) content of non-PEF treated samples increased.

Use of probiotic bacteria to improve growth and survivability of farmed New Zealand abalone (Haliotis iris)

The effects of two probiotic feeds containing two and three bacterial isolates were evaluated on the growth performance of New Zealand abalone (Haliotis iris). Probiotic bacteria were isolated from the guts of healthy adult abalone. The isolates were screened qualitatively and quantitatively according to their ability to hydrolyse nutrients (i.e. proteins, starch and alginate), produce acid and resist bile salts. Based on the screening results, we developed a multi-strain conglomerate of 2- and 3- probiotic bacterial strains that were supplemented into a commercial abalone feed to use in our experiments. The 2-probiotic conglomerate consisted of Exiguobacterium JHEb1 and Vibrio JH1, and the 3-probiotic conglomerate consisted of Exiguobacterium JHEb1, Vibrio JH1 and Enterococcus JHLDc. The probiotic feeding trial involved abalone juveniles (20–30 mm in maximum shell length). Both probiotic feeds significantly improved abalone growth compared to that of the unsupplemented feed. The 3-probiotic supplemented feed produced a significant shell length increase of 20.9%, a wet weight gain of 19.8% and a five-fold reduction in mortality compared to the controls. The 2-probiotic supplemented feed resulted in significant increases in shell length (15.4%) and reduced mortality (five-fold), but not in weight gain, compared to controls.

The toxic effects of three dinoflagellate species from the genus Karenia on invertebrate larvae and finfish

Three species of Kareniaceae, Karenia brevis, Karenia brevisulcata and Karenia mikimotoi were assessed for toxicity to juvenile Chinook salmon (Oncorhynchus tshawytscha), snapper (Pagrus auratus) and six species of marine invertebrate larvae (GreenshellTM mussel, pacific oyster, paua [New Zealand abalone], sea slug, sea urchin and brine shrimp). Karenia brevis was ichthyotoxic to juvenile salmon with a LT50 of 0.75 h at 0.18 × 106 cells L–1 but juvenile snapper were less sensitive (LT50 of 4.5 h at 5.9 × 106 cells L–1). Karenia brevisulcata also showed differential toxicity to juvenile salmon and snapper with LT50 of 0.48 h at 11 × 106 cells L–1 and 7.5 h at 16 × 106 cells L–1 respectively. However, no acute symptoms were observed in the fish following 48 h exposure to K. mikimotoi at 3.4 × 106 cells L–1. Karenia brevis at the highest level tested (8.7 × 106 cells L–1) did not cause observable symptoms in any of the invertebrate larvae over 24 h. Karenia mikimotoi only affected paua larvae (LT50 10 h at 12 × 106 cells L–1). Karenia brevisulcata was highly toxic to mussel, sea urchin and paua larvae (LT50 1–6.1 h at 7.5–9.6 × 106 cells L–1), toxic to sea slug and oyster larvae (LT50 6 h at 80 × 106 cells L–1 and 9.2 h at 34 × 106 cells L–1 respectively) but did not affect brine shrimp. Analysis of test cultures by liquid chromatography-mass spectrometry confirmed that K. brevis produced brevetoxins (52 pg cell–1; mainly brevetoxin-2). Karenia brevisulcata produced brevisulcatic acids (BSXs) and the more toxic Karenia brevisulcata toxins (KBTs). Karenia mikimotoi did not produce brevetoxin, BSXs or KBTs. The present study confirms the broad threats that blooms of K. brevisulcata pose to marine ecosystems and aquaculture, and the hazards of K. brevis to finfish and K. mikimotoi to abalone respectively.

Low to moderate levels of genetic differentiation detected across the distribution of the New Zealand abalone, Haliotis iris

Two regions of the mitochondrial genome (cytochrome oxidase I and ATPase 8–ATPase 6) were used to examine the population genetic structure of New Zealand’s endemic abalone (Haliotis iris). Samples were collected from 28 locations around New Zealand between January 2005 and February 2008. At least four phylogeographic breaks were present and occurred across the Chatham rise, in the western Cook Strait region, along the southeast coast of the South Island, and at East Cape in the North Island. Gene flow across the Chatham rise is probably limited due to infrequent dispersal across large geographic distances (~850 km), while factors limiting gene flow around the North and South Islands are less clear, and understanding these may require intense temporal and spatial sampling in complex hydrographic regions. High genetic diversity and weak genetic structure may be a general feature of abalone potentially reflecting large and/or ancient populations.

Settlement ofHaliotis australisLarvae: Role of Cues and Orientation of the Substratum

Haliotis australis is a medium-size New Zealand abalone with aquaculture potential. H. australis can be readily ripened and spawned, but larval settlement has proved difficult. The current study addressed aspects of larval settlement (i.e., attachment and metamorphosis) in laboratory experiments and small-scale hatchery trials. Competence to metamorphose was first seen weakly in larvae at 8 days old at 14.5°C, but larval metamorphosis rates increased progressively up to at least 12 days of age. In laboratory experiments, larvae showed a dose-dependent response to dissolved γ-aminobutyric acid (GABA), with settlement peaking at 1 µM (57% metamorphosis 4 days after settlement induction) and declining at higher and lower doses. Across a range of cues, metamorphosis was highest on crustose coralline algae (97 ± 4% metamorphosis after 4 days), intermediate on 1 µM GABA (55 ± 14%), and low on diatom films (<20%). GABA combined additively with diatom film to give strong metamorphosis (81 ± 6%). Metamorphosis induction by a diatom film was doubled if the film was pregrazed by juvenile H. australis (76% vs. 35%, P < 0.0001), but the grazing effect appeared to be species specific, because pregrazing by Haliotis iris had no effect (41% vs. 35%, P = 0.720). The species-specific response to trail mucus appears to preclude GABA as being the main inducer of metamorphosis in this case. On hatchery plates, settlement on pregrazed biofilms was approximately 4-fold higher when the plates were horizontal rather than vertical (41 % vs. 10% metamorphosis, P = 0.003). Settlement on ungrazed horizontal plates remained low even if those plates had been held in water with adult conspecifics, but without contacting the abalone. We conclude that tanks offering sloped or horizontal surfaces will be more effective than vertical plates for settlement of H. australis, and that pregrazed biofilms and/or GABA are promising settlement cues.

Validated estimation of growth and age in the New Zealand abalone Haliotis iris using stable oxygen isotopes

The growth and reproductive patterns of abalone are central to an understanding of the dynamics of their populations, and provide essential input into many of the stock assessment models currently used as the basis of assessing the sustainability of the fisheries. At present, most of this knowledge is obtained by tag-recapture methods, which are time consuming, often expensive and potentially confounding. The aim of the present study was to determine whether variations in the ratios of oxygen and carbon isotopes in the shells of Haliotis iris can be used to determine age, growth and reproductive patterns. Isotopic analyses of H. iris shells indicated that oxygen isotope profiles within the shells reflected ambient water temperature at the time of shell precipitation, and that these profiles could be used to determine age and growth patterns. To match the variation in isotopic ratios with ambient temperature cycles, we also adopted the novel approach of fitting a growth function to the data sets. The method should allow the collection of abalone growth information over the finer scales more appropriate for the rational management of abalone fisheries. Variations in the ratios of carbon isotopes showed no consistent patterns and, unlike some mollusc species, did not appear to be useful predictors of reproductive status at length.

Differentiation of Australian and New Zealand abalone species based on partialmitochondrial gene sequences of 12S rRNA, 16S rRNA and ND2 (NADHdehydrogenase subunit 2)

Partial sequences of mitochondrial ND2 (NADH dehydrogenase subunit 2), 12S rRNA and 16S rRNA genes were obtained from four Australian abalone species and two New Zealand abalone species. Phylogenetic analyses were conducted using the parsimony method. The resulting phylogenetic trees revealed two clades, one consisting of four Australian abalone species and the other containing two New Zealand abalone species. The possible application of ND2, 12S and 16S sequence for the investigation of abalone poaching is discussed.

Modelling transport of larval New Zealand abalone (Haliotis iris) along an open coast

The dispersal and transport of larval New Zealand abalone Haliotis iris was simulated using coupled two-dimensional hydrodynamic and Lagrangian particle-trajectory models. The aim was to estimate pelagic larval dispersal potential along the open coast, as a starting point from which basic management questions can be made for this recreationally and commercially important species. Larval dispersal was simulated from representative spawning sites under a range of representative hydrodynamic conditions, including wave-induced circulation cells. Larval presence over near-shore reef habitat declined as the energy of the flow field and corresponding larval dispersal and transport increased. Thus, spawning during high-energy conditions will promote dispersal and transport but reduce successful recruitment on near-shore reefs. This indicates that seeding of the adjacent coast is likely to be sporadic, with existing populations necessarily being somewhat self-recruiting. Results suggest that an ideal management system would ensure that adult populations were maintained at intervals of 10–30 km along the coast to maintain larval supply to areas in between. Dispersal characteristics were specific to the release site, and the simulations suggest that marine reserves can be positioned to accordingly achieve desired functions: for example, optimal choices can be made for seeding areas, recruitment or self-maintaining areas.

Demographic variation in the New Zealand abalone Haliotis iris

Growth data for the New Zealand abalone Haliotis iris were collected from 30 sites around the New Zealand coast by tag–recapture methods. Most data were collected to provide input into abalone stock assessments within discrete management areas, but had not been examined to determine the nature or extent of any large-scale patterns that might be useful to fishery managers. Sites spanned more than 10° of latitude and were subject to a large range of wave energies and temperatures. Mean monthly sea surface temperature (SST) and wave energy were estimated for each site and a generalised linear regression model was used to examine the relationship between variables. Size-at-maturity was also examined at ten sites. Initial length of abalone explained 35% of the variation in incremental growth, and a further 19% was explained by maximum SST, which also explained 60% of the variation in asymptotic length. Fastest growth was generally in areas with lower mean monthly maximum SST, and sites with the slowest growth had the highest mean monthly maximum SST. Size-at-maturity decreased with increasing temperature. The implications of these broad patterns upon abalone fisheries management strategies are discussed.

Thermal constraints on glycolytic metabolism in the New Zealand abalone, Haliotis iris: the role of tauropine dehydrogenase

Black‐foot abalone, Haliotis iris, were sampled from two populations in warm northern waters, and from two in colder southern waters. Abalone muscle is characterised by high activity of the glycolytic pyruvate reductase enzyme, tauropine dehydrogenase (TDH). Adductor muscle TDH was profiled for thermostability and activity to test the hypothesis that the enzyme may show adaptation in titre or kinetic characteristics reflecting thermal habitat. Temperature dependency of the apparent Michaelis‐Menten constant of TDH for pyruvate (appKmpyr) suggested eurythermal enzyme behaviour below 20°C, and compromised function at the higher temperatures of northern populations occurring in the summer months. Thermostability profiles and enzyme activities suggest TDH expression does not differ significantly among populations (P > 0.05), indicating that this locus shows no compensation for temperature. The optimal temperature for efficient TDH function, estimated from Vmax./appKmpyr, is close to 20°C. The possible thermal constraints on glycolytic metabolism in H. iris are discussed.

Molecular analysis of a haplosporidian parasite from cultured New Zealand abalone Haliotis iris.

In the Austral summer and autumn of 2000 and 2001, mortalities of black-footed abalone Haliotis iris (Martyn, 1784) occurred in a commercial facility in New Zealand. Histological analyses suggested that infection by a haplosporidian parasite was responsible. To confirm identification as a haplosporidian and to help determine if this parasite represented a new, undescribed species, DNA was extracted from infected host tissues scored as positive for infection by histological examination. Small-subunit rRNA (SSU rRNA) gene sequences from both the host abalone and a parasitic organism were amplified by PCR and characterized. Although the sequence for this parasite was novel, not matching any known SSU rRNA gene sequences, phylogenetic analyses strongly supported grouping this parasite with the haplosporidians. Parsimony analyses placed the parasite at the base of the phylum Haplosporidia, ancestral to Urosporidium crescens and the Haplosporidium, Bonamia, and Minchinia species. Sequencing of multiple parasite DNA clones revealed a single polymorphic site in the haplosporidian SSU rRNA gene sequence.

A length-based Bayesian stock assessment model for the New Zealand abalone Haliotis iris

We describe a length-based Bayesian model for stock assessment of the New Zealand abalone Haliotis iris (paua). We fitted the model to five data sets: catch-per-unit-effort (CPUE) and a fishery-independent survey index, proportions-at-length from both commercial catch sampling and population surveys, and tag–recapture data. We estimated a common component of error and used iterative re-weighting of the data sets to balance the residuals, removing the arbitrary data set weightings used in previous assessments. Estimates at the mode of the joint posterior distribution were used to explore sensitivity of the results to model assumptions and input data; the assessment itself was based on marginal posterior distributions estimated from Markov chain–Monte Carlo simulation. Assessments are presented for two stocks in the south of New Zealand. One may be recovering after recent catch reductions; the other is over-exploited and likely to decline further. Assessment for the first stock was robust; assessment for the second stock was sensitive to the CPUE data and may be too optimistic. We discuss future directions and potential problems with this approach.

The archaeogastropod molluscHaliotis iris: tissue and blood metabolites and allosteric regulation of haemocyanin function

We investigated divalent cation and anaerobic end-product concentrations and the interactive effects of these substances and pH on haemocyanin oxygen-binding (Hc-O(2)) in the New Zealand abalone Haliotis iris. During 24 h of environmental hypoxia (emersion), D-lactate and tauropine accumulated in the foot and shell adductor muscles and in the haemolymph of the aorta, the pedal sinus and adductor muscle lacunae, whereas L-lactate was not detected. Intramuscular and haemolymph D-lactate concentrations were similar, but tauropine accumulated to much higher levels in muscle tissues. Repeated disturbance and short-term exposure to air over 3 h induced no accumulation of D- or L-lactate and no change in [Ca(2+)], [Mg(2+)], pH and O(2)-binding properties of the native haemolymph. The haemolymph showed a low Hc-O(2) affinity, a large reverse Bohr effect and marked cooperativity. Dialysis increased Hc-O(2) affinity, obliterated cooperativity and decreased the pH-sensitivity of O(2) binding. Replacing Mg(2+) and Ca(2+) restored the native O(2)-binding properties and the reverse Bohr shift. L- and D-lactate exerted minor modulatory effects on O(2)-affinity. At in vivo concentrations of Mg(2+) and Ca(2+), the cooperativity is dependent largely on Mg(2+), which modulates the O(2) association equilibrium constants of both the high-affinity (K(R)) and the low-affinity (K(T)) states (increasing and decreasing, respectively). This allosteric mechanism contrasts with that encountered in other haemocyanins and haemoglobins. The functional properties of H. iris haemocyanin suggest that high rates of O(2) delivery to the tissues are not a priority but are consistent with the provision of a large O(2) reserve for facultatively anaerobic tissues during internal hypoxia associated with clamping to the substratum.