Haliotis Corrugata Research Articles

MEXICAN PINK ABALONE (Haliotis corrugata WOOD, 1828) FISHERY MANAGEMENT STRATEGY EVALUATION: A DATA-LIMITED APPROACH

Management procedures (MP) were evaluated to address alternative management of the pink abalone (Haliotis corrugata) fishery in the Mexican Pacific. This assessment utilized the Method Evaluation and Risk Assessment (MERA) platform within the context of management strategy evaluation (MSE). This species has been a crucial component of the abalone fishery in Mexico, with a history dating back to the 19th century. Since 1996, fishery authorities and fishermen have noted a decline in the stock biomass. In response, they implemented various strategies and efforts to address the situation. However, despite these measures, the stock has yet to recover satisfactorily. Eight MP were evaluated, and two corresponded to the status quo (current catch and effort). The simulation results suggest that relying solely on effort-based MP falls short of meeting the management objectives set in the reference points (Biomass and Yield). In contrast, alternative strategies involving different quota allocation strategies (e.g., based on the depletion level) demonstrated superior performance and a higher likelihood of meeting management objectives. Despite incorporating fishery information, the existing management procedures could have performed better in the simulation. Therefore, it is crucial to assess and implement alternative management strategies that are more likely to succeed

Seascape genomics of the pink abalone (Haliotis corrugata): An insight into a cross-border species in the northeast Pacific coast.

Seascape genomics gives insight into the geographic and environmental factors shaping local adaptations. It improves the understanding of the potential effects of climate change, which is relevant to provide the basis for the international management of fishery resources. The pink abalone (Haliotis corrugata) is distributed from California, United States to Baja California Sur, Mexico, exposed to a latitudinal environmental gradient in the California Current System. Management of the pink abalone contrasts between Mexico and the United States; Mexico has an active fishery organized in four administrative areas, while the United States has kept the fishery in permanent closure since 1996. However, the impact of environmental factors on genetic variation along the species distribution remains unknown, and understanding this relationship is crucial for effective spatial management strategies. This study aims to investigate the neutral and adaptive genomic structure of H. corrugata. A total of 203 samples from 13 locations were processed using ddRADseq, and covering the species' distribution. Overall, 2,231 neutral, nine potentially adaptive and three genomic-environmental association loci were detected. The neutral structure identified two groups: 1) California, United States and 2) Baja California Peninsula, México. In addition, the adaptive structure analysis also detected two groups with genetic divergence observed at Punta Eugenia. Notably, the seawater temperature significantly correlated with the northern group (temperate) and the southern (warmer) group. This study is a valuable foundation for future research and conservation initiatives, emphasizing the importance of considering neutral and adaptive genetic factors when developing management strategies for marine species.

Antimicrobial and anticarcinogenic activity of bioactive peptides derived from abalone viscera (Haliotis fulgens and Haliotis corrugata)

Bioactive peptides have been studied in several sources due to their valuable potential in the pharmaceutical and food industries. Abalone viscera, which are normally discarded as byproducts, are a rich source of protein. Thus, the aim of this study was to explore the potential bioactivity of peptides derived from abalone viscera (Haliotis fulgens and Haliotis corrugata) after hydrolysis with a commercial mixture of enzymes. The hydrolysates obtained were fractionated using gel filtration chromatography. The resulting hydrolysate fractions were investigated for their antimicrobial and cytotoxic activities, including the expression of gelatinases mmp-2 and mmp-9 in human prostate cancer cell lines (PC3). Results showed antimicrobial activity for protein fractions of H. corrugata against Proteus mirabilis and Pseudomona aeuroginosa (66.2–116.25 kDa), Bacillus subtilis (6.5–21.5 kDa), and Aspergillus niger (97.4–116.25 kDa), while H. fulgens peptide fractions (200–31 kDa) displayed activity against six bacterial strains, and fractions from 116.25 to 21.5 kDa had effects on the fungus A. niger, Alternaria alternata, and Aspergillus flavus. Additionally, protein fractions displayed cytotoxic activity, inhibiting 30.4–53.8% of PC3 cellular growth. Selected fractions decreased the PMA-induced and not-induced expressions of mmp-2 and mmp-9 in PC3 cells. Abalone viscera, as byproducts, can be used as a potential source of antimicrobial and anticancer peptides.

Rapid recovery of depleted abalone in Isla Natividad, Baja California, Mexico

AbstractIn the last decades, many marine invertebrates have experienced dramatic declines throughout many coastal marine ecosystems worldwide due to overfishing, disease outbreaks, and climate vulnerability. Despite extensive conservation and restoration effort, evidence of successful population recovery is rare. In this work, we document mass mortality events of pink and green abalone (Haliotis corrugata and Haliotis fulgens) in 2009–2010, and their subsequent rapid recovery following the continued enforcement and monitoring of two voluntary no‐take reserves by the local fishing cooperative (2006–present) and a 6‐year fishing closure (2012–2017) around Isla Natividad, Baja California Sur, Mexico. Age data collected from harvested abalone in 2019 suggest recruitment was maintained throughout the years when abundance was lowest following mass mortalities. The observed 6 to 8‐year time frame for recovery is consistent with scenarios presented in previous modeling studies, where marine reserves and other measures aimed at protecting large spawners predicted the potential for rapid recovery of abalone populations. This case study supports the effectiveness of a portfolio of resilience strategies, which include combining climate refugia and marine reserves, adherence to conservative annual fishing quotas, fishing closures, minimum size limitations, and ecological monitoring. Importantly, this example showcases how close collaboration between fishers, resource managers, scientists, and non‐governmental organization (NGOs) is critical for designing, implementing, and learning from conservation and management interventions to reverse marine population and ecosystem decline, reinforcing the legacy of Dr. Pete Peterson's life work on fully integrating ecology with marine management and restoration.

The Role of Diversity in Mediating Microbiota Structural and Functional Differences in Two Sympatric Species of Abalone Under Stressed Withering Syndrome Conditions.

Withering syndrome (WS) is a gastro-intestinal (GI) infectious disease likely affecting all abalone species worldwide. Structural and functional changes in abalone GI microbiotas under WS-stressed conditions remain poorly investigated. It is unclear if interspecific microbiota differences, such as the presence of certain microbes, their abundance, and functional capabilities, may be involved in the occurrence of this disease. Bacterial microbiotas of healthy Haliotis fulgens and Haliotis corrugata are mainly composed by Tenericutes, Proteobacteria, Fusobacteria, and Spirochaetes. We previously reported species-specific structural and functional profiles of those communities and suggested that they are of consequence to the different susceptibility of each species to WS. Here, we address this question by comparing the structure and function of healthy and dysbiotic microbiota through 454 pyrosequencing and PICRUSt 2, respectively. Our findings suggest that the extent to which WS-stressed conditions may explain structural and functional differences in GI microbiota is contingent on the microbiota diversity itself. Indeed, microbiota differences between stressed and healthy abalone were marginal in the more complex bacterial communities of H. corrugata, in which no significant structural or functional changes were detected. Conversely, significant structural changes were observed in the less complex bacterial microbiota of H. fulgens. Moreover, structural alterations led to a significant downregulation of some metabolic activities conducted by GI bacteria. Accordingly, results suggest that gastro-intestinal bacterial diversity appears to be related with both the health of abalone and the etiology of WS.

Effect of environmental variability on the individual growth of yellow abalone (Haliotis corrugata) and blue abalone (Haliotis fulgens) in the Mexican Pacific

Individual growth parameters of blue abalone and yellow abalone were estimated through length–frequency analysis using biometric data from bank surveys conducted by the National Fisheries Institute from 1998 to 2018. The growth parameters calculated by the von Bertalanffy equation are as follows: Haliotis corrugata (K=0.362 yr-1, L∞=150.5 mm and t0= -0.10 mm) and Haliotis fulgens (K=0.305 yr-1, L∞=163.5 mm and t0= -0.64 mm). When evaluating growth performance, through the Phi-prime growth index (∅′), indices of ∅′=3.36 for H. corrugata and ∅′=3.38 for H. fulgens were obtained. Subsequently, for the two species, a pattern of interannual variation in growth performance ∅′ was identified and had a positive correlation with sea surface temperature and fluorescence in the Mexican North Pacific, explaining 38% and 54%, respectively, of the variation in growth. This functional relationship between environmental parameters and growth opens the opportunity for more efficient management of the resource by discriminating sources of variation not caused by fishing and foreseeing abalone population conditions under different restoration and exploitation plans.

Neutral and adaptive population structure of pink abalone (Haliotis corrugata): fishery management implications

AbstractThe accurate definition of population units (stocks) and local adaptation are the cornerstones of fishery management. Unfortunately, this knowledge is unknown mainly for abalone species in the Northeast Pacific, where stocks have failed to recover. The pink abalone (Haliotis corrugata) is a fishing resource on the western coast of the Baja California Peninsula (BCP) and is currently catalogued as diminished with a recovery trending pattern. This research determined if the biological units matched the administrative and stock assessment units along the west coast of the BCP and the implications for fishery management. To test this hypothesis, a double digest restriction site-associated DNA sequencing approach was used to generate 1 733 neutral and 6 putative outlier loci for population genomic analysis. Neutral markers detected a smooth partition in two regional groups, the southern (San Juanico, La Bocana, Bahía Asunción, Puerto Escondido, Punta Eugenia, and Natividad Island) and northern regions (Cedros Island, Faro San José, San Jerónimo Island, and Guadalupe Island). Putative outlier loci indicated evident differentiation of those groups. The population subdivision at 28° latitude with both marker types was related to a biogeographic boundary. Results did not support the current administrative zones of pink abalone fisheries and contrasted with genetic homogeneity reports in the region.

Recruitment of Postlarval Abalone Haliotis spp. at Santa Catalina Island: Quantifying Natural Recovery

California abalone Haliotis spp., listed as species of concern, have been slow to recover, after 22 years of fishery closure, or are not recovering at all because of low-density populations and recruitment failure. It is not known if there is successful recruitment in populations in the wild in Southern California. This work examines, for the first time, whether newly settled abalones (<3 mm) are present in the wild at Santa Catalina Island to determine if recruitment is occurring. Natural cobbles with crustose coralline algae cover were sampled for recently settled abalones at two sites and at three depths over the reproductive season of green and pink abalone. A total of 128 abalone recruits (Haliotis spp.) were found over a cumulative rock surface area of 7.47 m2, on 325 cobbles, for a total recruitment density of 17.14 recruits per m2. Abalone recruits ranged in size from 220 to 2,120 µm, with an average recruit size of 490 ± 20 µm (mean ± SE, n = 124). Recruitment was similar across depths (2–4, 6–8, and 10–12 m) but differed between the two study sites, and was highest in June and September. Genetic work is needed to confirm species identification of the new recruits; however, they were most likely green abalone which would be consistent with the signs of green abalone recovery at the island. This work quantifies abalone settlement in Southern California, confirming successful recruitment. These methods can aid future restoration efforts empowering managers and restoration practitioners to monitor and quantify recruitment dynamics for abalones in California.

Growth Performance and Transcriptomic Response of Warm-Acclimated Hybrid Abalone Haliotis rufescens (♀) × H. corrugata (♂).

Along the Pacific coast of the Baja California Peninsula (Mexico), abalone represents one of the most lucrative fisheries. As wild populations are currently depleted, abalone farm production aims to balance the decreasing populations with the increasing demand. The Mexican abalone aquaculture is almost entirely based on red abalone (Haliotis rufescens). However, the increasing frequency of extreme temperature events is hampering this activity. The use interspecific hybrids can potentially improve abalone culture, as species have differences in their thermal tolerance. Therefore, the hybrid progeny between H. rufescens (♀) and pink abalone H. corrugata (♂), a temperate and a warmer water abalone species, respectively, will naturally support higher temperature. To test this hypothesis, growth rate, mortality and metabolic rate of both pure (RR) and hybrid abalone (RP) were assessed under the H. rufescens' optimum (18°C) and thermally stressed (22°C) conditions. To unveil the molecular pathways involved in the heat response, transcriptional profiling of both crosses was also investigated. At high temperature, we observed constrained growth and survival in RR while RP showed a significant increase in both rates, supporting the improved performance of the hybrid compared. These results match with the transcriptional profiling of hybrids showing higher expression of genes involved in growth and calcification, whereas in the pure red progeny, the transcriptional profile was mainly associated with the regulation of necroptosis process. Our results may contribute to propose new management plans to increase farm abalone production in Baja California.

Long-term analysis on the spawning activity of green (Haliotis fulgens) and pink (Haliotis corrugata) abalone along the central west coast of Baja California

The demand for abalone at international level makes it a high-commercial value product, and its fishing represents an important economic activity. Several research studies have described the reproductive biology of green (Haliotis fulgens) and pink (Haliotis corrugata) abalone to determine the spawning season, but no information is still available on the effects that long-term environmental factors have on them. Considering that the environmental variables are determinant in the reproductive cycle of marine invertebrates, this study intends to evaluate the long-term spawning activity (proportion of individuals on mature, spawning and postspawning stages) of green and pink abalone; for this purpose, monthly samples of green and pink abalone in the central west coast of the Baja California peninsula were analyzed from 1982 to 2013. Generalized additive models (GAM) were used to evaluate the effects of environmental factors on the spawning activity of green and pink abalone. The results indicated that the spawning season of green abalone extends from February to August, peaking from February to April when SST ranges from 17-20 °C with prevailing winds from the northwest, and the warm phase of El Niño Southern Oscillation (ENSO) decreases spawning activity of the species. With respect to pink abalone, the results indicated that the spawning season of the species occurs from September to November when sea surface temperature (SST) is higher than 22 °C with prevailing winds from the north during strong cold and warm phases of ENSO. These results suggest that the spawning activity of both species increase/decrease in the presence of warm/cold phases of ENSO since this large-scale climate phenomenon directly modifies local environmental conditions. These findings improve the current knowledge of the reproductive biology of green and pink abalone and indicate that spawning activity of both species peaks in different seasons. Therefore, current management strategy for abalone fishery closure should be modified.

Warm Water Shifts Abalone Recruitment and Sea Urchin Diversity in Southern California: Implications for Climate-Ready Abalone Restoration Planning

Nearshore kelp forest ecosystems are highly vulnerable to climate change and ocean warming, which can alter community dynamics and change the trajectory of species recovery in unpredictable ways. Abalone (Haliotis spp.) populations in the Southern California Bight (SCB) are still recovering from a combination of overfishing and disease, despite the closure of the fisheries 20 years ago and active restoration programs for abalone species in the region. For this study, abalone recruitment and sea urchin populations were surveyed in artificial habitats (16–22 m) across a spatial and temporal climatic gradient in southern California from 2010 to 2017 to inform the development of climate-ready abalone restoration programs. The SCB encompasses warm and cool islands, and experienced two periods of ocean conditions—cool (2010–2013) and warm ocean conditions (2014–2016). Dive surveys of the artificial habitats revealed that juvenile abalone recruitment remained low during the study period, suggesting that recovery is slow. Warm-water years favored recruitment of juvenile pink (Haliotis corrugata) and green abalone (Haliotis fulgens), with the highest abalone recruitment observed at Catalina Island. Endangered white abalone (Haliotis sorenseni) were not observed despite placing the artificial habitats in suitable deep rocky reefs, which is further evidence supporting their endangered species status. The coolest site, San Diego, had little abalone recruitment, with a few juvenile red abalone (Haliotis rufescens) and threaded (Haliotis kamtschatkana) abalone present. Sea urchin abundance and diversity increased during the warm period, with the largest increase at Catalina Island. During the warm period, Coronado sea urchin (Centrostephanus coronatus) increased in abundance, coincident with a decrease in the commercially valuable temperate red sea urchin (Mesocentrotus franciscanus). Potential shifts in the sea urchin assemblage to warm-water sea urchins may negatively impact recovering abalone populations and the red sea urchin fishery. Climate-ready abalone restoration will require ecosystem-based monitoring, tracking on not only abalone recruitment but also sea urchins, algal abundances, ocean temperature, and kelp forest communities as climate change may lead to complex and unexpected ecosystem interactions.

Fecundidad en gónadas maduras de Haliotis fulgens y Haliotis corrugata (Vetigastropoda)

Background: The term fecundity in abalone is defined according to an estimate of its absolute fecundity, which is the number of mature oocytes present in the gonad, or as potential fecundity, i.e., the total number of oocytes present in the gonad. In Mexico, few studies have estimated the fecundity of mollusks and these have been performed on gonads in different phases of gonadal development, obtaining values that are very different or overestimated, for example, values ranging from 80000 to 22 million oocytes in a gonad. Goals: Estimate the fecundity of Haliotis fulgens (blue abalone) and Haliotis corrugata (yellow abalone), using ma­ture gonads and a particle counter (Multisizer 3) to count only mature oocytes. Methods: Each month from October 2011 to February 2013, 30 adult organisms of each species were collected in two localities of Baja California Sur, Mexico (La Bocana and Bahia Tortugas). A histological analysis identified those that were mature females. To obtain the number of eggs per gram, triplicate oocyte counts were performed in a coulter counter Multisizer 3, in a solution of 4 g wet weight of mature oocytes diluted to 50 mL of filtered seawater (μm). Absolute fecundity was calculated by multiplying the total weight of the gonad by the number of mature oocytes present in one gram of oocytes. Results: The fecundity in La Bocana was found to be 2x106 eggs in H. corrugata and H. fulgens, while in Bahia Tortugas it was 4x106 eggs in H. fulgens. Conclusions: This study suggests that estimating absolute fecundity in species with partial spawning, such as H. fulgens and H. corrugata, should be per­formed on all females regardless of the degree of gonadal development. However, only mature oocytes should be considered as an indicator of absolute fecundity. Therefore, the use of an apparatus that counts and measures mature oocytes, such as a particle counter, facilitates and guarantees a good estimate of fecundity.

Structure, dynamics and predicted functional role of the gut microbiota of the blue (Haliotis fulgens) and yellow (H.corrugata) abalone from Baja California Sur, Mexico.

The GI microbiota of abalone contains a highly complex bacterial assemblage playing an essential role in the overall health of these gastropods. The gut bacterial communities of abalone species characterized so far reveal considerable interspecific variability, likely resulting from bacterial interactions and constrained by the ecology of their abalone host species; however, they remain poorly investigated. Additionally, the extent to which structural changes in the microbiota entail functional shifts in metabolic pathways of bacterial communities remains unexplored. In order to address these questions, we characterized the gut microbiota of the northeast Pacific blue (Haliotis fulgens or HF) and yellow (Haliotis corrugata or HC) abalone by 16S rRNA gene pyrosequencing to shed light on: (i) their gut microbiota structure; (ii) how bacteria may interact among them; and (iii) predicted shifts in bacterial metabolic functions associated with the observed structural changes. Our findings revealed that Mycoplasma dominated the GI microbiome in both species. However, the structure of the bacterial communities differed significantly in spite of considerable intraspecific variation. This resulted from changes in predominant species composition in each GI microbiota, suggesting host-specific adaptation of bacterial lineages to these sympatric abalone. We hypothesize that the presence of exclusive OTUs in each microbiota may relate to host-specific differences in competitive pressure. Significant differences in bacterial diversity were found between species for the explored metabolic pathways despite their functional overlap. A more diverse array of bacteria contributed to each function in HC, whereas a single or much fewer OTUs were generally observed in HF. The structural and functional analyses allowed us to describe a significant taxonomic split and functional overlap between the microbiota of HF and HC abalone.

Complete genome sequence of a phage hyperparasite of Candidatus Xenohaliotis californiensis (Rickettsiales) – a pathogen of Haliotis spp (Gasteropoda)

Bacteriophages are recognized as major mortality agents of microbes, among them intracellular marine rickettsiales-like bacteria. Recently, a phage hyperparasite of Candidatus Xenohaliotis californiensis (CXc) has been described. This bacterium is considered the causal agent of Withering Syndrome (WS) which is a chronic and potentially lethal disease of abalone species from California, USA and the peninsula of Baja California, Mexico. This hyperparasite which infects CXc could be used as a biocontrol agent for WS. Therefore, it is necessary to obtain genomic information to characterize this phage. In this study, the first complete genome sequence of a novel phage, Xenohaliotis phage (pCXc) was determined. The complete genome of pCXc from red abalone (Haliotis rufescens) is 35,728 bp, while the complete genome of pCXc from yellow abalone (Haliotis corrugata) is 35,736 bp. Both phage genomes consist of double-stranded DNA with a G+C content of 38.9%. In both genomes 33 open reading frames (ORFs) were predicted. Only 10 ORFs encode proteins that have identifiable functional homologues. These 10 ORFs were classified by function, including structural, DNA replication, DNA packaging, nucleotide transport and metabolism, life cycle regulation, recombination and repair, and additional functions. A PCR method for the specific detection of pCXc was developed. This information will help to understand a new group of phages that infect intracellular marine rickettsiales-like bacteria in mollusks.

Participatory management in a small-scale coastal fishery—Punta Abreojos, Pacific coast of Baja California Sur, Mexico

We describe the structure and historic landings of the Punta Abreojos fishing cooperative (Baja California Sur, Mexico) for the period between 2001 and 2015 to understand the dynamics of an economically and ecologically successful coastal fishing community according to catches and the direct income of fishers. A total of 21 commercial species were classified into three major groups: cultural resources, target resources and complementary resources. The most important resource in terms of total biomass was Paralabrax nebulifer (58.4%), followed by Panulirus interruptus and P. inflatus (13.6%). Seriola lalandi, Atractoscion nobilis, Caulolatilus princeps, Paralichtys californicus and P. woolmani made up minor proportions of the total biomass contributing 7.0%, 5.7%, 3.4% and 3.2% respectively. Haliotis fulgens and H. corrugata represented just 1.1% of the total biomass caught. Lobsters were the most profitable source of direct income for fisherman (77.5%), followed by the green and pink abalone (10.4%), barred sand bass (5.6%), white seabass (2.7%), California and speckled flounder (1.2%), yellowtail (1%) and whitefish (0.4%). The rest of the catch was composed of six species of finfish that represented 4.1% of the total catch biomass and 0.4% of the revenues from fishing.This work provides a first clear base-line description of the fisheries in Punta Abreojos which implements a management program that aims to ensure the wellbeing of the fishers and the fishery. The cooperative has been successful in maintaining catch at levels considered optimal to sustain revenues and continued annual landings. A management and cooperative structure that allows for adaptive change whilst maintaining revenues of the fishers is testament to the stewardship of the community and the participatory management upon which the community is built. For this reason, Punta Abreojos should be considered an example of a successful small-scale fishing cooperative that other, less successful fishing groups, can learn from.

Withering syndrome susceptibility of northeastern Pacific abalones: A complex relationship with phylogeny and thermal experience.

Population declines in wild and cultured abalones (Haliotis spp.) due to a bacterial disease called withering syndrome (WS) have been documented along the northeastern Pacific Ocean. However, observed differences in species susceptibility to the disease are not well understood. Here, we examined the susceptibility of three temperate abalone species, the cool water (4-14 °C) pinto or northern abalone (Haliotis kamtschatkana), the intermediate water (8-18 °C) red abalone (H. rufescens), and the warm water (12-23 °C) pink abalone (H. corrugata), to experimental WS infection at temperatures facilitating disease proliferation. Mortality data paired with histological and molecular detection of the WS pathogen confirmed that these abalone species exhibit different levels of susceptibility to infection and resistance to WS development ranging from high susceptibility and low resistance in pinto abalone to moderate/low susceptibility and resistance in red and pink abalones. The temperature associated with WS induced mortalities also varied among species: pinto abalone died at the lowest experimental temperature (17.32 ± 0.09 °C), while red abalone died at an intermediate temperature (17.96 ± 0.16 °C), and pink abalone required the highest temperature (18.84 ± 0.16 °C). When data from the current and previous studies were examined, susceptibility to WS was inversely related to phylogenetic distance from white abalone (H. sorenseni), which had the highest susceptibility and lowest resistance of all abalone species tested prior to the current study. These results provide further evidence that an abalone's thermal optima and phylogenetic relationship can determine its susceptibility to WS; species with cool water evolutionary histories are most susceptible to WS and the most susceptible species appear to be closely related. Differences among the thermal ranges of abalone species have broad implications for WS disease dynamics and highlight the importance of understanding the mechanisms governing the abalone-WS relationship in order to properly manage declining abalone populations.

Spatial distribution of abalone (Haliotis fulgens and H. corrugata) and its time variability; implications for their management.

Abalone fisheries in the central pacific coast of Baja California relies on the exploitation of Haliotisfulgens (green abalone) and H. corrugata (pink abalone). Their catch is regulated under a quotas system annually assessed by the fisheries authority. Because they are sedentary species it is assumed that their density and biomass are roughly constant along the time. Thus, annual biomass assessments are realized only once a year. However, a central question emerges: whether this assumption is true, or density and biomass are changing even in a short time? To respond this question, submarine surveys were carried out at different times, in eight reefs along the same fixed sampling stations. Results showed that both the density and spatial distribution changed just after 24 and 72 h. Similar changes were observed 24 days later. Total abundance changed from 79 specimens at the beginning of the experiment to 46 at the end. In some sites, abundance falls less than 50 %. Changes in spatial distribution wereobserved commonly. The average of the minimum distance within the abalone patches was 0.5 m; however, most patches were only of 2 individuals. We conclude that it is necessary to undertake more than one annual survey assessment to attain average confident figures of density and biomass population, with less uncertainty. Furthermore,assessments should include measurement of size and frequency of the patches, which should be numerous enough to guarantee a successful reproduction, in-order-to maintain the stocks at a sustainable level.

Hyperparasitism by the bacteriophage (Caudovirales) infecting Candidatus Xenohaliotis californiensis (Rickettsiales-like prokaryote) parasite of wild abalone Haliotis fulgens and Haliotis corrugata from the Peninsula of Baja California, Mexico

Candidatus Xenohaliotis californiensis (CXc) is a Rickettsiales-like prokaryote that is considered the causal agent of Withering Syndrome (WS), a chronic disease of abalone, from the west coast of North America and it is listed by the International Organization for Animal Health (OIE) as a reportable agent due to its pathogenicity. This bacterium in red abalone Haliotis rufescens, black abalone Haliotis cracherodii, and yellow abalone Haliotis corrugata from California, US and Baja California, Mexico has been found to be infected by a bacteriophage. To date, there is no information on the epizootiology of CXc and its bacteriophage in natural populations of abalone; furthermore, it is unknown if the bacteriophage was also present in CXc infecting blue abalone Haliotis fulgens. The objective of this study was to determine the distribution, prevalence and intensity of CXc, as well as to determine the distribution and prevalence of the bacteriophage and to study interactions between host sex and hyperparasitism in blue abalone and yellow abalone. Tissue samples were obtained from seven localities where the commercial capture of wild abalone is carried out. Samplings were conducted throughout the 2012–2013 capture seasons and a total of 182 blue abalone and 170 yellow abalone were obtained. The prevalence and intensity of CXc and the prevalence of the bacteriophage were determined by histology. The identity of CXc was confirmed by PCR, product sequence analysis and in situ hybridization while the identity of the bacteriophage was corroborated by TEM. The prevalence of CXc infected and uninfected by the bacteriophage was 80% in blue abalone and 62% in yellow abalone. Low infection intensities were found in 86% of blue abalone and 82% of yellow abalone. Infection intensity was significantly higher in undifferentiated yellow abalone. The bacteriophage in CXc showed a prevalence of 22% and 31% in blue abalone and yellow abalone respectively. These results show that CXc and its bacteriophage are widely distributed in the peninsula of Baja California and that they are well established in natural populations of blue abalone and yellow abalone. Additionally, this data constitutes the first record of a bacteriophage in blue abalone.

Differences in Diet of Green (Haliotis fulgens) and Pink (Haliotis corrugata) Wild Abalone along the Pacific Coast of the Baja California Peninsula, Using Stable Isotope Analyses

ABSTRACT Stable isotopes (δ13C, δ15N) were used to assess differences in the diets of wild adult Haliotis fulgens and Haliotis corrugata. Temporal variations in the diets of these species were compared using specimens collected monthly during one annual cycle in Laguna La Bocana, whereas comparisons were made with samples taken in October 2012 in Bahia Tortugas. The two species of abalone have different feeding habits year round; H. corrugata showed a constant d15N pattern (between 9.5‰ and 10.4‰), whereas H. fulgens exhibited a seasonal δ15Npattern [the lowest frequency (9.5‰) occurred in September and the highest (11.8‰) in December], which might indicate that this species fed on the resources that were available at the time. The d13C pattern showed that Laguna La Bocana had depleted values in relation to Bahia Tortugas, indicating different carbon sources. The fact that the d15Npattern of abalone was below the known food sources (macroalgae), suggests the presence of other sources in the diet of adult ...

Diatom species diversity in the diet of healthy and sick specimens of adult Haliotis fulgens and Haliotis corrugata

Se analizo la diversidad de especies de diatomeas en la dieta de abulones azul (Haliotis fulgens) y amarillo (H. corrugata) del NW de Mexico. Esta se referencio con valores de indices de condicion y hepatogonadico (considerados como indicadores de la salud y cambios reproductivos, respectivamente) en ambas especies de abulon, incluyendo especimenes enfermos con sindrome de deshidratacion (WS). Las hipotesis enunciaban que: a) las asociaciones representadas en contenidos intestinales de H. fulgens vs. H. corrugata mostrarian una estructura tipica con muchos taxa raros y pocas especies abundantes; b) que no habria diferencia en la estructura de dichas asociaciones de diatomeas; y c) que las asociaciones de diatomeas en abulones con sindrome de deshidratacion serian similares a las de especimenes sanos. Para contrastar las hipotesis se examinaron abulones sanos, recolectados entre febrero 2012 y febrero 2013, y especimenes enfermos recolectados entre marzo y mayo 2012. Los especimenes se pesaron y se midieron para calcular los indices de condicion y hepatogonadico. Para analizar la diversidad de especies de diatomeas en contenidos intestinales de abulones se disecaron especimenes de 7 fechas de muestreo entre marzo y septiembre 2012. Las muestras de diatomeas se describieron con base en la abundancia relativa de las especies, indices de diversidad y de similitud. Para este periodo, 19 taxa de diatomeas comprendieron el 80% de las abundancias relativas; los mas abundantes fueron Cocconeis scutellum, Gomphonemopsis pseudexigua, Grammatophora gibberula, Bacillaria socialis y Striatella unipunctata. La diversidad de especies de diatomeas fue alta en todas las muestras. Estos valores y la similitud medida entre muestras indican que ambas especies de abulon se alimentaron de las mismas asociaciones de diatomeas disponibles in situ a lo largo de este periodo. Las muestras de diatomeas de especimenes enfermos representaron asociaciones similares a las de especimenes sanos. Por lo tanto, no hubo evidencias para rechazar ninguna de las hipotesis planteadas.