New Zealand abalone (Haliotis iris) holds ecological, economic, and cultural value, with wild stocks supporting fisheries and an emerging aquaculture industry. Wild-caught adult abalone are often used as broodstock, but captivity can affect spawning and offspring quality. This study is the first to profile wild and farmed H. iris broodstock using histology, proximate composition, microbiome, and metabolomics analyses. Histology showed higher gonadal abnormalities in farmed abalone, while wild abalone exhibited increased ciliates in their gills, indicating richer marine–microorganism interactions. Microbiome analyses revealed a higher microbial richness and diversity in the buccal cavity of wild abalone. The core microbiota phyla across both groups included Proteobacteria, Bacteroidota, Campylobacterota, Fusobacteria, and Firmicutes. Proximate analyses showed higher muscle protein in farmed abalone, while gonadal tissue partitioned by sex showed higher fat in females and higher protein in males. Metabolomics revealed altered amino acid metabolism in the adductor muscle, carboxylic acid metabolism in the gonad, and fatty acid metabolism in the foot. This investigation expands our understanding of the physiological and microbial differences between wild and farmed abalone, showing altered gonad and muscle conditions from prolonged captivity and highlighting the need for greater microbial diversity in cultured stocks.

Recreational fishing effects on New Zealand abalone (pāua, Haliotis iris) after five years of fishery closure: a matrix-based approach.

A multi-platform metabolomics approach to investigate the effects of acute thermal stress on New Zealand black-footed abalone (Haliotis iris)

ABSTRACT This study investigated the potential for paralytic shellfish toxin (PST) accumulation in three of Aotearoa New Zealand's (NZ) taonga seafood species: kina (urchin; Evechinus chloroticus), pāua (abalone; Haliotis iris) and hohehohe (geoduck; Panopea zelandica) in laboratory exposures to the dinoflagellate Alexandrium pacificum. Although PST accumulation data are scarce or non-existent for these three species, international studies have reported toxin accumulation in related genera. Given the prevalence of harmful algal blooms (HABs) in areas of NZ where these species are harvested, this research aimed to assess PST uptake in different tissue types (e.g. viscera, siphons, flesh) following a seven-day controlled exposure to the PST-producing A. pacificum. Results showed that while the filter feeding hohehohe exceeded regulatory PST limits in the viscera following exposure, the two grazing species (kina and pāua) did not accumulate PSTs beyond the regulatory limit of 0.8 mg STX.2HCl eq kg−1 in 7 days. However, A. pacificum DNA and PSTs were detected in the viscera of all species, confirming ingestion of the microalgal cells. This is the first controlled PST-uptake study of these economically and ecologically important species, providing valuable insights into the risks of paralytic shellfish poisoning following collection of these species after a HAB event.

Many abalone populations worldwide are in decline as a result of changing climate and fishing pressure. In New Zealand (NZ) Haliotis iris is the largest and most abundant of the endemic abalone species. This species displays high levels of phenotypic variation with slow-growing populations having an impact on their commercial utilisation. The present study incorporates targeted histopathological approaches to characterise tissue-level factors in abalone from NZ's principal fishing region. Adult (n=60) and sub-adult (n=56) H. iris were collected from two Chatham Island sites that display differential growth rates; sampling was repeated on six occasions over three years. Through histology the slower-growing adult population was observed to have an elevated ceroid score, higher prevalence of kidney stones and increased prevalence of a plasmodia stage of haplosporidian-like parasites in the right kidney, when compared with the faster-growing and sub-adult populations. Furthermore, the faster-growing adult population appeared to be retaining mature oocytes over the predicted spawning season with higher-than-expected atresia (oocyte degeneration). Factors implicated in growth performance between the two populations include site, environment, parasites, pathology, reproduction, ceroid deposition and previously reported nutritional status. The 18S PCR and metabarcoding on the right kidney tissue were negative for haplosporidian/Urosporidium previously reported in H. iris, with metabarcoding results detecting an apicomplexan ancestral group. The reproductive, somatic and parasite findings from the current study provides critical information on abalone physiological condition which allows facilitation of early detection of conditions that may impact the sustainability and management of H. iris stocks in New Zealand under a changing climate. For instance, changes to reproductive condition may reduce oocyte quality and quantity thereby reducing recruitment to the next generation.

Context Subtidal, adult pāua experience irregular food supply. The effects of prolonged starvation have not been examined. Aim To examine effects of 105-day starvation on body mass, respiration and haemolymph proteins. Methods Pāua, maintained at 15°C, were divided into groups that were either fed Macrocystis pyrifera, or starved; each group was further divided between pāua whose haemolymph was sampled at intervals and those sampled only at the beginning and end of the experimental period. Body mass, condition, oxygen uptake and gonad index were measured at the start and end. Key results Total mass of both fed and starved groups did not change significantly. The condition of the starved individuals decreased significantly. Haemocyanin accounts almost entirely for haemolymph proteins. The haemolymph haemocyanin concentration in fed abalone fell by 17–27% over 105 days, and by 49–63% in starved individuals. Final normoxic oxygen uptake was similar in starved and fed pāua and declined similarly during hypoxia. Conclusions Pāua may survive extended periods of starvation by metabolising body tissues and haemocyanin, with only minor changes in their mass, condition and aerobic respiration. Implications These primitive gastropods have mechanisms to survive stressors associated with low food availability. Maintenance of body volume in this osmoconformer supports gill perfusion and the functioning of the hydraulic skeleton in locomotion.

ABSTRACT With the collapse of global populations, New Zealand has one of the last wild abalone fisheries. The blackfoot abalone (Haliotis iris) supports important customary, commercial and recreational harvests, but environmental stressors and overfishing have prompted restoration and stock enhancement efforts. We used field surveys to quantify effects of the 2018 commercial outplanting of 167,000 hatchery-raised juvenile abalone following the catastrophic Kaikōura earthquake. We tested alternative enhancement methods by outplanting swimming larvae and rocks with settled post-larvae. Annual surveys at seven sites found that outplanted juveniles comprised 12% of the sampled population after three years, amid unexpectedly high natural recruitment. Recaptured outplants grew well at c. 25 mm yr−1 but showed poor growth at two densely populated sites. After three years, >50% of recaptured individuals had likely reached sexual maturity. Outplanting 200,000 competent swimming larvae into natural habitats had no effect after three months compared to controls. However, the outplanting of rocks settled with larvae resulted in a significantly greater density of small (≤15 mm) recruits compared to controls, signalling potential for this method as a practical and scalable enhancement strategy. The insights from this research help clarify the benefits and limitations of three stock enhancement methods and inform future efforts.

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.

ABSTRACT Abalone is a gourmet seafood with a high commercial value, particularly when obtained as a live product. During live transportation, abalone encounter stressors causing biochemical modifications to tolerate the changes. Using semi-targeted metabolomics, this study characterised the left and right gill metabolite profiles of Blackfoot abalone, Haliotis iris, following transportation (48 h) and recovery (48 h). This study reports the association between left and right gill metabolites, to enhance our physiological understanding of the interplay between gills. The left gill metabolites are mainly active following transportation, while both gills partake in the metabolite response following recovery. Transportation necessitated increased metabolites linked to the glycolysis pathway, the Krebs cycle, amino acid, and nucleotide metabolism, for energy production, achieved via aerobic and anaerobic pathways. The recovery phase supported the replenishing of glycogen, triglycerides, and protein stores, albeit metabolic homeostasis was not achieved following two-days of water immersion recovery. This study showcases the well-adapted metabolic mechanisms implemented by H. iris in response to transportation stress and show that metabolites are in the process of returning to the same concentrations as measured pre-transport stress. The findings herein can be applied to improve animal health during transport and subsequent survival, which in-effect supports profitability.

Histopathological investigation of four populations of abalone (Haliotis iris) exhibiting divergent growth performance

Context Climate change and increased seawater temperatures can greatly affect physiological processes and growth of marine ectotherms, including the blackfoot haliotid, Paua (Haliotis iris). Scope for growth (SFG) is a laboratory-derived measure of the energy available for growth but this has not been examined in Paua. Aims To measure SFG of seasonally collected Paua and their haemolymph parameters at constant acclimation temperatures of 12, 15, 18 and 21°C for 28 days. Methods Energy available for growth was measured from kelp food and losses due to respiration and ammonia excretion calculated on Days 1, 14, 21 and 28 of acclimation. Haemolymph parameters were also measured. Key results After 3 days of acclimation, SFG was highly variable. Following 2 weeks of acclimation, SFG was positive for all temperatures. Respiration and excretion energies depended on both acclimation temperature and time. Haemolymph parameters were affected by acclimation temperature. Conclusion Paua have limited ability to acclimate to a temperature 21°C suggesting that they would not grow effectively at this temperature. Implications This research suggests that adult Paua can be adversely affected by increased seawater temperature, resulting from climate change and this could affect their future growth and distribution.

ABSTRACT Limited supply of sustainable feed ingredients is a significant concern for future aquaculture practices. Alternative ingredients, such as insect meal and grape marc, are suitable for aquaculture nutrition due to their nutritional profile and more sustainable production methods. This study assessed the effect of dietary insect meal and grape marc on gut microbial composition, digestive system morphology, and muscle metabolome of Haliotis iris. Juvenile abalone were fed four encapsulated experimental diets with varying levels of insect meal/grape marc and a commercial feed for 165 days in a commercial farm. The gut health of abalone was evaluated through histopathology, and 16S rRNA amplicon libraries through Illumina MiSeq sequencing. The abalone metabolome was evaluated through gas chromatography-mass spectrometry (GC-MS). Results showed that animals had good intestinal condition across all dietary treatments. Microbiome analysis revealed increased relative abundances of bacteria (Firmicutes and Fusobacterium) associated with the breakdown of polysaccharides in diets including insect meal and grape marc. Metabolite profile variations indicate that the inclusion of insect meal and grape marc favoured fatty acid metabolism and amino acid catabolism, respectively. This study provides foundation to produce more sustainable feeds including insect meal and grape marc without affecting the gut and overall health of abalone.

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.

The aquaculture industry has been criticised for the excessive use of fish meal (FM) in feeds due to the utilisation of wild fish in the formulation and the exacerbation of overfishing marine resources. Land-based abalone aquaculture mainly uses commercial feeds (CFs) to promote faster growth, which include FM as a primary protein component. Alternative ingredients, such as insect meal (IM) and grape marc (GM) are potential candidates for FM replacement due to their suitable nutritional profile and sustainable production. This paper reports on a novel nutritional approach for the New Zealand farmed abalone, which replaces FM with IM by 10% and includes a waste by-product (GM) by 30% as a potential prebiotic source. The study was performed in two stages: (a) physico-chemical determination of diets delivered in an alginate matrix (experimental diets) and their stability in seawater compared to CF and (b) evaluation of growth and feed intake for the New Zealand black-foot abalone. There were significant differences between experimental diets and CF in terms of sinking rate, particle weight, and microscopic observations. Water stability of the experimental diets was increased by 50% in 24 and 48 hr compared to CF, producing less solid waste, and potentially reducing cleaning efforts in the farm. The inclusion of IM and GM did not compromise overall animal growth or their feed conversion ratio, however, further evaluation need to be explored in the future research. The findings revealed that the developed encapsulated feeds are a more stable food delivery method for Haliotis iris compared to the CF. Furthermore, both IM and GM can be included in feed formulations as a more sustainable strategy without compromising weight and shell gains in the abalone farming.

Seasonal variations play a crucial role in the physiology, immune responses, and nutritional profile of aquatic animals. Unpredictable water temperature fluctuations, especially those caused by climate change, may negatively affect feed consumption and growth of cultured organisms, such as abalone. In addition, metabolic and nutritional changes across different seasons may have significant effects on aquaculture production. This study aimed to investigate biochemical and metabolic alterations in healthy abalone (Haliotis iris) during 1 year of grow out in a land-based farm in New Zealand. Proximate analyses were used to identify nutritional variations in whole animal tissues, and a gas chromatography–mass spectrometry-based metabolomics approach was used to identify metabolic changes in adductor muscle of abalone during different seasons in the 1-year sampling period. Results showed that protein content was higher in warmer months compared with colder months, whereas lipid, ash, and carbohydrate contents remained generally constant throughout the year. Metabolic profile fluctuations indicated higher amounts of glutamic acid, glutathione, methionine, lysine, serine, tyrosine, and glycine in January and March compared with October and July, indicating possible amino acid breakdown and collagen degradation due to warmer temperatures. Although the proximate analyses findings revealed no signs of nutritional deficiencies in abalone among seasons, the metabolic profiles suggested possible thermal stress during summer months. This study provides a foundation for further nutritional studies to optimise seasonal diets for farmed Haliotis iris and highlights the need to monitor thermal stress effects, especially during summer and/or heatwave events.

Almost 60% of the fish meal produced globally is used in aquaculture feeds. Fish meal production relies on finite wild-marine resources and is considered as an unsustainable ingredient. Insect meal (IM) is considered a sustainable source with high levels of protein suitable for growth promotion. Grape marc (GM) is a waste byproduct of the winery industry rich in pigments with antioxidant capacity. However, the inclusion of both ingredients can affect the flavor of the meat of abalone and the color of the shell due to different nutritional profiles. The aim of this study was to evaluate the effect of the dietary inclusion of IM and GM on the flavor volatile compounds and shell color of the juvenile Haliotis iris in a 165-days feeding trial. Abalone were offered four experimental diets with different levels of IM and GM inclusion and a commercial diet (no IM or GM). Soft bodies of abalone were used to characterize volatile compounds using solid-phase microextraction gas chromatography–mass spectrometry, and color changes were analyzed in ground powder of abalone shells using color spectrophotometry 400–700 nm (visible). The results showed 18 volatile compounds significantly different among the dietary treatments. The inclusion of IM did not significantly affect the flavor volatile compounds detected, whereas the inclusion of GM reduced volatile compounds associated with lipid-peroxidation in abalone meat. The inclusion of IM and GM did not significantly affect the lightness nor the yellowness, blueness, redness, and greenness of the ground shells. The supplementation of abalone feeds with GM can help to reduce off-flavour compounds which may extend shelf-life of raw abalone meat.

Metabolomics approach reveals size-specific variations of blackfoot abalone (Haliotis iris) in Chatham Islands, New Zealand

An evaluation of the growth and immunity of New Zealand black-footed abalone (Haliotis iris) treated with encapsulated feed and probiotics

Drivers of fishery status for the cultural keystone pāua (Haliotis iris) in Customary fishery Protection Areas in Aotearoa New Zealand

Abalone, locally called pāua, is a valuable export product in New Zealand, contributing between NZD $50-60 million annually towards the country’s export economy [1]. Generally, one of the most significant bottlenecks of land-based abalone aquaculture is the high cost of the feed, which can be up to 50% of the production cost [2]. The high price has been attributed to fish meal, which is a key ingredient used in aquaculture feeds due to its excellent amino acid profile and palatability. However, fish meal use has been questioned due to the utilisation of wild fish to feed farmed fish and the exacerbation of overfishing marine resources [3]. Alternative ingredients, such as insects and winery waste products, are potential candidates as protein replacements due to their suitable nutritional profile and more sustainable production. This study aims to 1) develop and characterise alternative formulated feed for pāua (Haliotis iris) using insect meal and grape pomace and 2) evaluate the nutritional and growth alterations in juvenile pāua receiving different formulated feeds for 6 months. Proximate analysis is used to identify nutritional variations in body and faecal matter, and liquid/gas chromatography–mass spectrometry (LC/GC–MS) analyses are utilised to characterise amino acid and fatty acid profiles in tissue samples. Results show a high animal survival rate of 95% and increased seawater stability of experimental diets compared to a commercial feed. Nutritional analyses show no significant variations in animal tissues in terms of protein proportions and amino acid profiles, but differences were found in the lipid proportions and fatty acid profiles. This research will present the evidence to support the potential use of insect meal and grape marc as fishmeal replacements in abalone feeds, leading to a more sustainable aquaculture.