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An international Workshop on Rebuilding Abalone Stocks in British Columbia was held during February 23-26, 1999, in Nanaimo, British Columbia, Canada. The main goal of the workshop was to develop a realistic strategy to rehabilitate depleted northern (pinto) abalone, Haliotis kamtschatkana, stocks in British Columbia.

The Pacific abalone ( Haliotis discus hannai ) is the most economically valuable shellfish species in Northeast Asia, accounting for most of the shellfish production in South Korea. Despite the continuous improvement in the productivity of domestic abalone aquaculture, rapid seawater temperature changes caused by global warming have led to mass mortality in coastal abalone farms. Therefore, research on environmental stressors is urgently needed to prevent abalone production losses. This study analyzed the expression of heat shock protein ( HSP ) genes in foot muscles of H. discus hannai and metabolic parameters including glucose, lysozyme, catalase, D‐lactate, and trehalose levels in the hemolymph under acute high temperature, low temperature, low salinity, and air exposure. Quantitative reverse‐transcription polymerase chain reaction analysis showed that HSP20 expression was downregulated in all experimental groups, whereas HSP70 expression increased immediately in all experimental groups except for the low‐temperature stress group. Hemolymph analysis showed that glucose and lysozyme levels increased significantly immediately after treatment in all groups, and decreased during the recovery period. Together, the results indicate that low water temperature stress had the smallest effect on abalone among the treatments. We conclude that the other treatments acted as stressors of abalone and that HSP genes, glucose, and lysozyme can be used as stress indicators in H. discus hannai .

Much attention is being devoted to the potential of marine sulfated polysaccharides as antiviral agents in preventing COVID-19. In this study, sulfated fucoidan and crude polysaccharides, extracted from six seaweed species (Undaria pinnatifida sporophyll, Laminaria japonica, Hizikia fusiforme, Sargassum horneri, Codium fragile, Porphyra tenera) and Haliotis discus hannai (abalone viscera), were screened for their inhibitory activity against SARS-CoV-2 virus entry. Most of them showed significant antiviral activities at an IC50 of 12~289 μg/mL against SARS-CoV-2 pseudovirus in HEK293/ACE2, except for P. tenera (IC50 > 1000 μg/mL). The crude polysaccharide of S. horneri showed the strongest antiviral activity, with an IC50 of 12 μg/mL, to prevent COVID-19 entry, and abalone viscera and H. fusiforme could also inhibit SARS-CoV-2 infection with an IC50 of 33 μg/mL and 47 μg/mL, respectively. The common properties of these crude polysaccharides, which have strong antiviral activity, are high molecular weight (>800 kDa), high total carbohydrate (62.7~99.1%), high fucose content (37.3~66.2%), and highly branched polysaccharides. These results indicated that the crude polysaccharides from seaweeds and abalone viscera can effectively inhibit SARS-CoV-2 entry.

Abalone viral ganglioneuritis (AVG), caused by Haliotid herpesvirus-1 (HaHV-1; previously called abalone herpesvirus), is a disease that has been responsible for extensive mortalities in wild and farmed abalone and has caused significant economic losses in Asia and Australia since outbreaks occurred in the early 2000s. Researchers from Taiwan, China, and Australia have conducted numerous studies encompassing HaHV-1 genome sequencing, development of molecular diagnostic tests, and evaluation of the susceptibility of various abalone species to AVG as well as studies of gene expression in abalone upon virus infection. This review presents a timeline of the most significant research findings on AVG and HaHV-1 as well as potential future research avenues to further understand this disease in order to develop better management strategies.

In this research work, an approach using You Only Look Once version three (YOLOv3)-TensorFlow for abalone detection and Deep Simple Online Real-time Tracking (DeepSORT) for abalone tracking in conveyor belt systems is proposed. The conveyor belt system works in coordination with the cameras used to detect abalones. Considering the computational effectiveness and improved detection algorithms, this proposal is promising compared to the previously proposed methods. Some of these methods have low effectiveness and accuracy, and they provide an incorrect counting rate because some of the abalones tend to entangle, resulting in counting two or more abalones as one. Conducting detection and tracking research is crucial to achieve modern solutions for small- and large-scale fishing industries that enable them to accomplish higher automation, non-invasiveness, and low cost. This study is based on the development and improvement of counting analysis tools for automation in the fishing industry. This enhances agility and generates more income without the cost created by inaccuracy.

Abalone Haliotis midae are distributed from the cold, hypercapnic waters of the dynamic Benguela Current Large Marine Ecosystem to the relatively warm, normocapnic waters of the Agulhas Current. The species supports an important fishery as well as a thriving aquaculture industry. Due to the relatively low capacity to regulate their acid–base balance and their need to calcify shell and radula, abalone are especially vulnerable to increasing ocean acidification. Exposure to acidified seawater, i.e., hypercapnia, also occurs during the farming operation and can originate from (a) changes in influent seawater, (b) pH decrease by accumulation of waste products, and (c) intentional hypercapnia for anaesthesia using CO2-saturated seawater for size grading. Currently, these are acute exposures to hypercapnia, but increasing ocean acidification can cause chronic exposure, if not mitigated. Wild South African abalone are already exposed to periodic hypercapnia during ocean upwelling events and will be more so in the future due to progressive ocean acidification. This study investigated the acute pH effects in isolation as an initial step in studying the acute physiological response of H. midae to provide a mechanistic basis for the design of complex multifactorial studies, imitating more closely what occurs on farms and in the natural habitat. The major findings relevant to the above conditions are as follows: 1. Acute exposure to hypercapnia induces a reversible, unbuffered respiratory acidosis. 2. The impact of acute hypercapnia is size-dependent and potentially fatal. 3. Exposure to extreme, short hypercapnia during anaesthesia causes a rapid imbalance in the acid–base state but a rapid subsequent recovery. LC50 for small, medium and large abalone range from pH 6.27 to 6.03, respectively, and sub-lethal levels from pH 6.8 to 6.2. These results can be used by abalone aquaculture farms to mitigate/avoid the impact of acute (and chronic) hypercapnia but also to standardise their anaesthesia method. They are also a proxy to estimate the effects on wild populations.

The deepening of color of ready-to-eat (RTE) abalone during storage leads to sensory quality degradation, which seriously affects the shelf life of products and consumers’ purchasing desire. The goal of this study is to look into the causes of non-enzymatic browning and lipid oxidation, as well as how to control them, and their effect on the color of RTE abalone during storage. The control, bloodletting and antioxidants groups (lactic acid, citric acid and 4-hexylresorcinol) of RTE abalone were stored for 0, 20 and 40 days at 40 °C, respectively, to explore the rule and mechanism of the color change in RTE abalone. This research shows that RTE abalone undergoes browning during storage. Meanwhile, the content of reducing sugar, phenols and unsaturated fatty acids decreases, while the formation of lipid hydroperoxides and aldehydes increases during storage. In addition, the color change in RTE abalone during storage is mainly related to the Maillard reaction, while the lipid oxidation mainly forms pyrrole and participates in the Strecker degradation process as part of the Maillard reaction. The quality of RTE abalone can be maintained by controlling browning effectively as well as lipid oxidation through bloodletting and the addition of antioxidants to ensure that RTE abalone has high storage stability. According to our research, bloodletting and the addition of antioxidants to RTE abalone have a good application prospect and popularizing value in the storage of RTE abalone.

Background Heterosis has been exploited for decades in different animals and crops due to it resulting in dramatic increases in yield and adaptability. Hybridization is a classical breeding method that can effectively improve the genetic characteristics of organisms through heterosis. Abalone has become an increasingly economically important aquaculture resource with high commercial value. However, due to changing climate, abalone is now facing serious threats of high temperature in summer. Interspecific hybrid abalone ( Haliotis gigantea ♀ ×  H. discus hannai ♂, SD) has been cultured at large scale in southern China and has been shown high survival rates under heat stress in summer. Therefore, SD has become a good model material for heterosis research, but the molecular basis of heterosis remains elusive. Results Heterosis in thermal tolerance of SD was verified through Arrhenius break temperatures (ABT) of cardiac performance in this study. Then RNA-Sequencing was conducted to obtain gene expression patterns and alternative splicing events at control temperature (20 °C) and heat stress temperature (30 °C). A total of 356 (317 genes), 476 (435genes), and 876 (726 genes) significantly diverged alternative splicing events were identified in H. discus hannai (DD), H. gigantea (SS), and SD in response to heat stress, respectively. In the heat stress groups, 93.37% (20,512 of 21,969) of the expressed genes showed non-additive expression patterns, and over-dominance expression patterns of genes account for the highest proportion (40.15%). KEGG pathway enrichment analysis showed that the overlapping genes among common DEGs and NAGs were significantly enriched in protein processing in the endoplasmic reticulum, mitophagy, and NF- κ B signaling pathway. In addition, we found that among these overlap genes, 39 genes had undergone alternative splicing events in SD. These pathways and genes may play an important role in the thermal resistance of hybrid abalone. Conclusion More alternative splicing events and non-additive expressed genes were detected in hybrid under heat stress and this may contribute to its thermal heterosis. These results might provide clues as to how hybrid abalone has a better physiological regulation ability than its parents under heat stress, to increase our understanding of heterosis in abalone.

The sabellid polychaete Terebrasabella heterouncinata Fitzhugh and Rouse, 1999, originally from southern Africa, is an invasive species in temperate regions recorded for the first time in Mexico in 2023 infesting green ( Haliotis fulgens Philippi) and red ( H. rufescens Swainson) abalone reared under intensive conditions in recirculation aquaculture systems (RAS). In the 1980s, T. heterouncinata was accidentally introduced to California (USA) with the South African abalone H. midae Linnaeus to conduct research for commercial farming. The sabellid spread through abalone farming facilities reaching nearby intertidal zones. Some inadvertently infected red abalone were imported to Baja California (Mexico) from Californian farms for abalone research and cultivation in the 1990s, but there were still no reports of the species. This study deals with the early detection and removal of the sabellid in research-cultured abalone, assesses its prevalence and intensity in red and green abalone, and addresses its potential for introduction in Mexico. The worms inhabited tubes embedded within the host shell, its growing edge and around the respiratory pores, thus affecting shell uniformity, hardness, and aesthetics but not causing abalone deceasing. In one case, an abalone showed imperforated respiratory pores, indicating severe shell deformities. After carefully removing and cleaning, the polychaete was eliminated from the RAS facilities. Currently, T. heterouncinata is considered a significant pest of marine gastropods in the USA, Chile, Iceland, and South Africa. Green and red abalone hold a high ecological, cultural, and commercial value and are the primary species commercially cultivated in Baja California. Given the invasive potential of T. heterouncinata , which can affect the local abalone aquaculture and trade, its introduction has been prohibited in Mexico. The finding reported in this paper emphasises the need to evaluate the invasiveness, assess the potential environmental impact and propose strategies to reduce economic risks for the regional aquaculture industry.

Dried abalones are precious products, in which candy abalone is the most treasured one, owing to its unique taste. After rehydration and simmering, the core part tastes extraordinarily tender and viscoelastic, just like a soft candy which may almost melt in mouth. However, the reason for this has yet to be elucidated. The purpose of this study is to research the formation mechanism of the candy-like core in candy abalone. First of all, we characterized the viscoelasticity, microstructure and protein changes of candy abalone during the simmering process. The texture results indicated that the springiness and adhesiveness of candy abalone showed an increase. Scanning and transmission electron microscopy suggested that myofibrillar protein in candy abalone formed a dense three-dimensional network hydrogel structure. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis revealed such a hydrogel structure might be derived from the degradation of the myofibrillar protein during the drying process. Also, we identified degraded peptides mainly stemmed from paramyosin by mass spectrometry. Moreover, molecular dynamics simulation revealed that the hydrogen bonds and hydrophobic interactions are mainly responsible for the self-assembly of peptides during the rehydration and simmering stages. Different from reported protein hydrogels, the rheological and morphological properties of the formed peptide hydrogels in candy abalone have significant changes. In this study, we found that the myofibrillar protein of fresh abalone degraded into peptides during the drying process, which further cross-linked to form a peptide hydrogel during the rehydration and simmering stages, thereby producing a unique viscoelastic candy-like core in candy abalone.