Mycteroperca Rosacea Research Articles

Natural spawning of the leopard grouper (Mycteroperca rosacea) in captivity in La Paz, Mexico

Natural spawning of the leopard grouper (Mycteroperca rosacea) was studied in captivity from 2004 to 2008 under natural photoperiod conditions. Fish spawned naturally in 2006, but only 90,000 unfertilized eggs were collected. A total of 43 and 27 spawning days were observed in 2007 and 2008, respectively. Spawning season began in March and lasted until May–June and was related to an increase in water temperature from 21.1 to 23.8 °C. The mean (SE) number of eggs released each day was 101,705 (13,876) in 2007 and 40,510 (7,874) in 2008, and the total number of eggs collected in 2007 and 2008 was 4.37 × 106 and 1.07 × 106, respectively. The number of eggs collected per month was not significantly different within each year (P > 0.05), although a significant difference was observed between 2007 and 2008 (P < 0.05). The annual relative number of eggs released was 288,750 eggs·kg–1 in 2007 and 72,919 eggs·kg–1 in 2008, and viable egg production was 184,800 eggs kg–1 in 2007 and 25,375 eggs kg–1 in 2008. The fertilization rate (%) of the eggs collected daily differed significantly throughout the spawning season of 2007 (P < 0.05). The fertilization rate also differed (P < 0.05) between 2007 (61.10%) and 2008 (32.30%). Statistical analysis of the 2 consecutive spawning seasons indicated no correlation between the fertilization rate and fecundity. The effect of the moon phase on spawning was also considered. The fish spawned at dusk before total darkness. Mean (SD) egg diameter was 864.0 ± 22.0 μm.

Essential (Cu, Zn) and nonessential (Pb, Cd) metals in the muscle of leopard groupers (Mycteroperca rosacea) from a mining port in the Gulf of California, Mexico: human health risk assessment.

Mining activities are a current environmental issue due to heavy metal release and subsequent metal uptake by organisms. In this study, we quantified the concentrations of essential (Cu, Zn) and toxic (Cd, Pb) elements in the muscle of 248 leopard groupers, Mycteroperca rosacea, captured by spearfishing and free diving close to a mining district in the Gulf of California during 2014-2015. We analysed metals using high-resolution inductively coupled plasma source mass spectrometry (HR-ICP-MS). We analysed metal concentrations by fish size, sex, maturity, season, year and risk factor for human consumption. The results indicated common levels of essential elements (Cu: 11 ± 34.3μg/g, Zn: 377 ± 1390μg/g) in comparison with toxic elements (Cd: 0.06 ± 0.1μg/g, Pb: 0.98 ± 1.5μg/g). Cadmium was within the permissible limit of Mexican standards (0.5μg/g), but lead content bordered its limit (1.0μg/g). Heavy metal concentrations were comparable between males and females. Metal variations were not significantly correlated with sex, maturity, season or year (p > 0.05). The evaluation of benefits (daily mineral intake) and risks (target hazard quotients) to health indicated that these fish did not represent a risk of adverse effects to consumers within worldwide limits, while the nutritional benefits were high.

Social-ecological networks and connectivity within and between two communities of small-scale fishers in Mexico

Aligning the ecological and social dimensions of the connections present between users that harvest a shared natural resource is a necessary step toward sustainable management. However, contrasting estimates of connectivity across disciplines is a challenging task and few empirical studies have focused on population dynamics within fish species with a complex life history. We used a collaborative approach merging citizen science, population genetics, oceanographic modeling, and interviews to collect empirical connectivity data of individual fish, fishing sites, and fishers. We integrated the data within a multilevel social-ecological network framework describing the interactions between two communities of small-scale fishers (Bahia Kino and Puerto Libertad, Sonora, Mexico) targeting leopard grouper (<em>Mycteroperca rosacea</em>). We identified two types of social-ecological links, including the use of specific fishing sites by individual fishers and the harvest of individual fish by individual fishers. Despite their fishing zones not overlapping, the ecological links between two communities located ~150 km apart were consistent and reciprocal where fishing grounds from each community acted as a source of fish to the other during the larval or juvenile/adult stages, respectively. As a result, fishers from the two communities frequently captured fish that were second-degree relatives. In contrast, the probability of social ties among fishers changed significantly depending on the type of connection and was considerably low for leadership and kinship although some communication was present. Our study highlighted how local actions (e.g., recovery from marine reserves or overfishing) are likely to impact the neighboring community as much as locally. The geographic scale and strength of key ecological process supporting fish stocks through the fish life cycle seem to be larger than those of social connections among fishers. Fishers and managers could benefit from a broader regional perspective that strengthens connections between communities about shared goals and activities. We examine some insights learned on the constraints of connectivity given different attributes of each ecological and social component and methodological challenges identified. We also discuss ways to improve collaborative management between the two communities.

Reproductive biology of the leopard grouper Mycteroperca rosacea (Streets, 1877) in the coastal area of Santa Rosalia, BCS, Mexico

The leopard grouper Mycteroperca rosacea is endemic to northwestern Mexico. It has been classified as vulnerable by the IUCN since 2008. M. rosacea has high commercial value and is caught yearround in Baja California Sur (BCS). Biological information on this species, especially in its natural environment, is scarce, and the objective of this study was to analyze its reproductive biology in Santa Rosalia, BCS. A total of 345 specimens were collected from March 2014 to May 2015. The sex ratio was 2.0: 1.0 (females: males, P < 0.05). Population size at first maturity (L 50 ) was estimated at 40.77 cm TL; 37.31 cm TL for males and 42.44 cm TL for females. Gonadic development was synchronous by group, with a reproductive period occurring from March to May in 2014 and 2015 (at 20-23oC). The gonadosomatic index achieved maximum values in May 2014 and March 2015, as did the highest frequencies of mature and spawning individuals, indicating that there was a clear seasonal pattern of reproduction, and a negative correlation with temperature for both sexes. The hepatosomatic index and the condition index indicated that M. rosacea is not a species that requires storing of energy for reproductive events, as it seems to have food available year-round. Normal 0 21 false false false ES X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; line-height:115%; mso-pagination:widow-orphan; font-size:12.0pt; mso-bidi-font-size:11.0pt; font-family:Times New Roman,serif; mso-bidi-font-family:Times New Roman; mso-bidi-theme-font:minor-bidi; mso-ansi-language:ES; mso-fareast-language:EN-US;}

Reproductive cycle of leopard grouper Mycteroperca rosacea (Streets, 1877) held in captivity: relation ship between gonad development and sex steroid concentration

In this study, sex steroids (E2, T, and 11-KT) concentrations in blood of captive leopard grouper ( Mycteroperca rosacea ) and their relation togonad development were determined during a reproductive cycle. Each month, gonad samples from 24 fish were obtained to analyze gonadal maturation and blood was extracted to determine steroid levels. Throughout the year, ovaries showed a higher percentageof primary oocytes. In January, oocytes at early and late vitellogenesis stages increased progressively; from March to June, ovulation rates were high. In females, estradiol levels increased from March and decreased after the spawning season. Lower levels of testosterone were found during the spawning season and 11-KT remained without significant changes throughout the year. Males exhibit a significant increase in E2 from March until July; testosterone remained without significant variation throughout theyear, and 11-KT plasma levels increased from March until July and decreased after the spawning season. In this study, we verified the sex change of an organism and the concentrations of sexual steroids were determined and discussed.

Social factors and aromatase gene expression during adult male-to-female sex change in captive leopard grouper Mycteroperca rosacea

Social factors and aromatase gene expression in the leopard grouper Mycteroperca rosacea was studied when captive fish were separated by sex during the reproductive (April–June) and post-reproductive (July–September) seasons. Monosex females, monosex males, and mixed-sex, held in social sextet units were analyzed for sex steroids throughout confinement. At the end of the experiment, the gonad-sex was defined by histology, and gonad and brain aromatase gene expressions were quantified. Only males held in the monosex social units changed sex. Histology showed one male remained unchanged, six were found in a transitional sexual stage, in which two had intersex-predominantly-testes, and four had a more defined intersex ovo-testes pattern, and 11 were immature de novo females (neofemales). Neofemales and most intersex fish did not survive. In spring, 11-ketosterone showed a specific male profile, which suggests that male-to-female sex change was not triggered during the reproductive season. The low steroid levels in summer made it impossible to associate the sex change to a gonad hormonal shift; in September, gonad aromatase gene expression was not significantly different among groups. However, brain aromatase expression in intersex fish was significantly higher than monosex females, mixed-sex females, and neofemale groups. These results suggest that in the absence of female hormonal compounds, and at a time when male gonad steroidogenesis was diminished, the brain mediated male-to-male social-behavioral interactions, including stress, by increasing aromatization, resulting in derived intersex-male, which triggered more aromatization, followed by a sex change.

Incidence of xanthism in the leopard grouper Mycteroperca rosacea (Perciformes: Serranidae) in the Gulf of California

Five leopard grouper Mycteroperca rosacea specimens were captured in the Gulf of California, two of which presented a rare orange pigmentation on both sides of the body. The remaining individuals presented changes to the normal pigmentation pattern on the left or right flanks. The possible causes of these phenomena are discussed.

Simultaneous Germinal Vesicle Migration and Oil Droplet Coalescence Predict Final Oocyte Maturation in the Leopard Grouper

AbstractThe size of oocytes during germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) was revised for the Leopard Grouper Mycteroperca rosacea. Histology of ovaries, plasma levels of estradiol‐17ß (E2), and testosterone (T) were analyzed in Leopard Grouper at 0, 12, 16, and 24 h after a priming dose of 1,000 IU/kg body weight of human chorionic gonadotropin (hCG) and were compared with control females injected with saline solution. Histological observations were verified in hormonally induced females by observing in vivo intraovarian biopsies after using the same priming dose and a second resolving dose of 500 UI/kg body weight of hCG 16 or 24 h later, which served to analyze spawning performance. Histological and in vivo intraovarian biopsies showed that in full‐yolk oocytes (~455 μm diameter) GVM and GVBD were concomitant with coalescence of a single oil droplet 16 and 24 h after the first injection. The oil droplet became a morphological marker as well as a predicting indicator of the competence and synchronization of maximum vitellogenic oocytes and the effectiveness to respond to hormonal therapy. In the experimental fish group E2 and T reached peaks at the same time, which were significantly higher than those in the controls. Mean fecundity was 168,000 eggs/kg, mean fertilization was 88%, and mean viability was 71% (114,000 eggs/kg), all of which were within the range of other cultivated groupers. These results can be used to improve the induction of final maturation in the Leopard Grouper in captivity and may be used in other species of Mycteroperca that show the same marker.

Incorporating historical and ecological genetic data for leopard grouper (Mycteroperca rosacea) into marine reserve design in the Gulf of California

Effective design of marine reserves for use in fisheries management and conservation requires a clear understanding of patterns of larval transport and sink-source dynamics between populations, as well as a clear understanding of population demography. Mitochondrial and nuclear markers were analyzed to investigate potential mechanisms impacting connectivity among and the demographic history of subpopulations of a commercially important species in the Gulf of California, the leopard grouper (Mycteroperca rosacea). Demographic history and connectivity analyses included a coalescent analysis, estimating neutrality indices, estimating global and pairwise F’ST, ΦST, or G’’ST, and a priori methodologies to identify genetically distinct units and barriers to dispersal. Average, long-term connectivity between geographic regions in the Gulf was also estimated. Divergence of mitochondrial lineages of leopard grouper dated to the late Pleistocene, with deep-water islands serving as demographically stable populations that may have acted as sources for new populations during periods of climate variability. Additionally, we observed genetically distinct units of leopard grouper in the Gulf, particularly between peninsular and mainland sites, as well as asymmetrical migration between the northern and central Gulf. Observed patterns of genetic differentiation are likely attributed to complex asymmetrical oceanographic currents and local larval retention. Based on our genetic findings and current fishing pressure in certain regions, we recommend implementing small, upstream no-take zones in the areas east of Isla Angel de la Guarda, around Isla San Lorenzo and Isla San Esteban, and north of Isla Tiburon, that would enhance connectivity among subpopulations, preserve sites with high genetic diversity, and benefit fisheries downstream of these sites.

Asymmetric connectivity of spawning aggregations of a commercially important marine fish using a multidisciplinary approach.

Understanding patterns of larval dispersal is key in determining whether no-take marine reserves are self-sustaining, what will be protected inside reserves and where the benefits of reserves will be observed. We followed a multidisciplinary approach that merged detailed descriptions of fishing zones and spawning time at 17 sites distributed in the Midriff Island region of the Gulf of California with a biophysical oceanographic model that simulated larval transport at Pelagic Larval Duration (PLD) 14, 21 and 28 days for the most common and targeted predatory reef fish, (leopard grouper Mycteroperca rosacea). We tested the hypothesis that source–sink larval metapopulation dynamics describing the direction and frequency of larval dispersal according to an oceanographic model can help to explain empirical genetic data. We described modeled metapopulation dynamics using graph theory and employed empirical sequence data from a subset of 11 sites at two mitochondrial genes to verify the model predictions based on patterns of genetic diversity within sites and genetic structure between sites. We employed a population graph describing a network of genetic relationships among sites and contrasted it against modeled networks. While our results failed to explain genetic diversity within sites, they confirmed that ocean models summarized via graph and adjacency distances over modeled networks can explain seemingly chaotic patterns of genetic structure between sites. Empirical and modeled networks showed significant similarities in the clustering coefficients of each site and adjacency matrices between sites. Most of the connectivity patterns observed towards downstream sites (Sonora coast) were strictly asymmetric, while those between upstream sites (Baja and the Midriffs) were symmetric. The best-supported gene flow model and analyses of modularity of the modeled networks confirmed a pulse of larvae from the Baja Peninsula, across the Midriff Island region and towards the Sonoran coastline that acts like a larval sink, in agreement with the cyclonic gyre (anti-clockwise) present at the peak of spawning (May–June). Our approach provided a mechanistic explanation of the location of fishing zones: most of the largest areas where fishing takes place seem to be sustained simultaneously by high levels of local retention, contribution of larvae from upstream sites and oceanographic patterns that concentrate larval density from all over the region. The general asymmetry in marine connectivity observed highlights that benefits from reserves are biased towards particular directions, that no-take areas need to be located upstream of targeted fishing zones, and that some fishing localities might not directly benefit from avoiding fishing within reserves located adjacent to their communities. We discuss the implications of marine connectivity for the current network of marine protected areas and no-take zones, and identify ways of improving it.

Residency and seasonal movements in Lutjanus argentiventris and Mycteroperca rosacea at Los Islotes Reserve, Gulf of California

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 501:191-206 (2014) - DOI: https://doi.org/10.3354/meps10711 Residency and seasonal movements in Lutjanus argentiventris and Mycteroperca rosacea at Los Islotes Reserve, Gulf of California Thomas TinHan1,*, Brad Erisman2, Octavio Aburto-Oropeza2, Amy Weaver3, Daniel Vázquez-Arce3, Christopher G. Lowe1 1Department of Biological Sciences, California State University Long Beach, Long Beach, California 90815, USA 2Marine Biology Research Division, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093-0202, USA 3Sociedad de Historia Natural Niparajá A.C., 23020 La Paz, Baja California Sur, Mexico *Corresponding author: t.tinhan@gmail.com ABSTRACT: A detailed understanding of inter- and intraspecific movement patterns is required to understand how marine species interact with surrounding ecological communities, their susceptibility to anthropogenic disturbance (e.g. fishing pressure), or the feasibility of management strategies. Between August 2010 and September 2012, we used acoustic telemetry to continuously monitor movements of 31 Lutjanus argentiventris (yellow snapper) and 25 Mycteroperca rosacea (leopard grouper) at Los Islotes, a small no-take reserve and reported spawning site for both species in the SW Gulf of California. Though the majority of fish from both species exhibited moderate levels of site fidelity to Los Islotes (snapper: present 49 ± 30% of days since tagging, grouper: 64 ± 30%), cluster analyses revealed multiple patterns of site fidelity within species. Approximately 30% of snapper exhibited decreases in site fidelity during the spawning season, and snapper did not spawn at the reserve during the study. Grouper spawning aggregations at Los Islotes were visually observed in 2011 and 2012, though the abundance of fish and the intensity of courtship behaviors were reduced in comparison with reported aggregations elsewhere in the Gulf. Three snapper and 2 grouper made repeated movements across pelagic waters between Los Islotes and Marisla Seamount, another documented aggregation site in the SW Gulf. The demonstrated variation in movements of these species over multiple temporal and spatial scales warrants consideration of movement patterns in assessments of reserve performance, as well as the combination of traditional fisheries regulations (e.g. size limits) with marine reserves throughout the Gulf. KEY WORDS: Reef fishes · Yellow snapper · Leopard grouper · Marine Protected Areas · MPAs · Acoustic monitoring · Fish spawning aggregations Full text in pdf format PreviousNextCite this article as: TinHan T, Erisman B, Aburto-Oropeza O, Weaver A, Vázquez-Arce D, Lowe CG (2014) Residency and seasonal movements in Lutjanus argentiventris and Mycteroperca rosacea at Los Islotes Reserve, Gulf of California. Mar Ecol Prog Ser 501:191-206. https://doi.org/10.3354/meps10711 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 501. Online publication date: March 31, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Single or combined effects of Lactobacillus sakei and inulin on growth, non-specific immunity and IgM expression in leopard grouper (Mycteroperca rosacea)

The aim of this study was to evaluate the single or combined effects of Lactobacillus sakei with inulin suitable for immunological in vivo studies in farmed fish. By in vitro assays, L. sakei strain 5-4 showed antibacterial activities against all assayed fish pathogens (except the Vibrio harveyi strain CAIM-1793). L. sakei was able to survive at high fish bile concentrations. Fermentation of the agave inulin resulted in a large increase in number of lactobacilli. For the in vivo study, fish were fed for 8 weeks four practical diets: control diet (control), L. sakei 5-4 (10(7) CFU/g), inulin (1% or 10 g/kg) and L. sakei + inulin (10(7) CFU/g + 10 g/kg). The weight gain showed clearly the synergistic effect of L. sakei 5-4 and inulin at 6 and 8 weeks of treatments. Leopard grouper fed with L. sakei alone or combined with inulin have significantly increased the assayed physiological and humoral immune parameters. By real-time PCR assays, the mRNA transcripts of immunoglobulin M (IgM) were found to be higher expressed in intestine, head kidney, mucus, gill, spleen and skin. Moreover, mRNA expression levels of IgM in head kidney and anterior intestine were measured by real-time PCR. L. sakei 5-4 and L. sakei + inulin supplemented diet up-regulated the expression of IgM at week 4 and 8 in intestine and head kidney, respectively. These results support the idea that the L. sakei 5-4 alone or combined with agave inulin improved growth performance and stimulates the immune system of leopard grouper.

Changes in digestive enzyme activities during larval development of leopard grouper (Mycteroperca rosacea)

The leopard grouper is an endemic species of the Mexican Pacific with an important commercial fishery and good aquaculture potential. In order to assess the digestive capacity of this species during the larval period and aid in the formulation of adequate weaning diets, this study aimed to characterize the ontogeny of digestive enzymes during development of the digestive system. Digestive enzymes trypsin, chymotrypsin, acid protease, leucine-alanine peptidase, alkaline phosphatase, aminopeptidase N, lipase, amylase and maltase were quantified in larvae fed live prey and weaned onto a formulated microdiet at 31days after hatching (DAH) and compared with fasting larvae. Enzyme activity for trypsin, lipase and amylase were detected before the opening of the mouth and the onset of exogenous feeding, indicating a precocious development of the digestive system that has been described in many fish species. The intracellular enzyme activity of leucine-alanine peptidase was high during the first days of development, with a tendency to decrease as larvae developed, reaching undetectable levels at the end of the experimental period. In contrast, activities of enzymes located in the intestinal brush border (i.e., aminopeptidase and alkaline phosphatase) were low at the start of exogenous feeding but progressively increased with larval development, indicating the gradual maturation of the digestive system. Based on our results, we conclude that leopard grouper larvae possess a functional digestive system at hatching and before the onset of exogenous feeding. The significant increase in the activity of trypsin, lipase, amylase and acid protease between 30 and 40 DAH suggests that larvae of this species can be successfully weaned onto microdiets during this period.

Isolation and characterization of fifteen microsatellite loci in Leopard grouper (Mycteroperca rosacea) via 454 pyrosequencing

Leopard grouper (Mycteroperca rosacea) are distributed from Bahia Magdalena, through the Gulf of California and as far south as Jalisco, Mexico. They are listed as Vulnerable on the IUCN Red List due to significant fishing-induced declines over the past decade. Microsatellite loci were isolated by constructing a shotgun genomic library and sequencing using 454 XL + titanium chemistry. We characterized 15 polymorphic loci in 120 samples from three geographic locations. Genotyping yielded 15–60 alleles per locus with observed levels of heterozygosity ranging from 0.575 to 0.975.

Effective ecosystem-based management must encourage regulatory compliance: A Gulf of California case study

The Northern Gulf of California is an area important for small-scale fisheries in terms of economic activity and food security, but widespread non-compliance with fisheries regulations impedes effective management of resources and conservation efforts. Where a previous study evaluated quantitatively a theoretical situation in which all regulations are perfectly followed, this article compares a suite of recently proposed ecosystem-based management (EBM) policies against the expected benefits of full enforcement of current regulations. Policies evaluated include no-take marine protected areas (MPAs), breeding period closures, changes in hook size and fishing effort, and gear-specific spatial closures. No-take MPAs yield ecological benefits over a wide range of MPA sizes and characteristics, but do not increase overall catch. Seasonal closures are effective at reducing overfishing for the depleted leopard grouper ( Mycteroperca rosacea ); changing the hook size of artisanal longlines does not increase catch of either the target species or the assemblage, and gear-specific fishery closures for crab traps near Puerto Peñasco are effective at reducing overfishing of blue crab ( Callinectes bellicosus and C. arcuatus ). In general, full enforcement of existing regulations outperforms these EBM policies in terms of conservation benefits, but it may be less palatable to stakeholders as it requires major reductions in catch. ► The Northern Gulf of California is represented using a biogeochemical ecosystem model. ►Fisheries and conservation benefits are estimated for four new EBM policies. ► Outcomes are compared to a reference scenario: full-enforcement of existing rules. ► In most cases, full-enforcement outperforms new EBM policies. ► Future EBM policy development must include efforts to improve regulatory compliance.

Leukophilia during maturation of the leopard grouper Mycteroperca rosacea

In spring, peripheral blood of mature-ripe female leopard groupers showed leukophilia after an increase of lymphocytes and thrombocytes, followed by a differential increase of monocytes and granulocytes. In mature-ripe males, granulophilia and thrombophilia were evident. Leukocytes were distinguishable in some ovarian blood vessels where post-ovulatory follicles were present. These observations suggest coordination of endocrine-immune activity, where, after one spawning event, leukocytes infiltrate the gonad tissue from the peripheral blood to aid with immune surveillance and phagocyte activity, while a feedback of sex steroids and vitellogenesis occurs in preparation for the next spawning. An abundance of leukocytes may also aid in gonad reabsorption during post-spawning. Leukophilia coincided with high plasma concentrations of oestradiol and testosterone, which together with leukocytes, decreased greatly in immature-active groupers in summer. Blood cell counts, erythroblasts, and haematocrit of mature-ripe groupers in spring were significantly lower than immature-active groupers in summer, suggesting mild anorexia induced by reproductive behaviour.

Reproductive cycle of the leopard grouper Mycteroperca rosacea in La Paz Bay, Mexico

The leopard grouper Mycteroperca rosacea is an endemic species from the northwestern coast of Mexico and, like other serranid fishes, it has a high commercial value; hence, it is a good candidate for cultivation. This study aimed to describe the reproductive cycle of the leopard grouper in the wild as a step toward evaluating its aquaculture and restocking potential. From March 2008 to February 2009, 197 specimens were collected in the Gulf of California, Mexico. Overall sex ratio was 3.6 females to 1.0 male. Significant differences (P &lt; 0.05) in total length and body weight were found between sexes. Group-synchronous ovarian development was observed with one yearly spawning period from May to June. Males matured two months earlier than females. The reproductive cycle was divided into four periods: (1) maturation, (2) spawning, (3) post-spawning, and (4) resting. Significant variations in the gonadosomatic index, hepatosomatic index, visceral fat index, and condition factor were observed throughout the study period. In addition, nine individuals were classified as immature bisexuals and one grouper presented evidence of sex change.

Effects of dietary supplementation with probiotic live yeast Debaryomyces hansenii on the immune and antioxidant systems of leopard grouper Mycteroperca rosacea infected with Aeromonas hydrophila

Two trials were conducted to determine the e⁄cacy of ¢sh fed live yeast Debaryomyces hansenii strain CBS 8339 on immune and antioxidant systems in leopard grouper Mycteroperca rosacea infected with Aeromonas hydrophila .J uveniles (12� 0.5 g) were fed with a control diet or a D. hansenii-supplemented diet (10 6 colony-forming units per gram) for 5 weeks. The live weight of ¢sh was registered on a weekly basis. After 4 weeks, ¢sh from each treatment were immunocompromised with pathogenic A. hydrophila and further fed for1week in order to evaluate the eiect on immunological and antioxidant parameters. Generally, the results showed enhanced growth performance in ¢sh fed the diet containing yeast compared with the control. Addition of live yeast had no signi¢cant eiect on the immunological parameters after 4 weeks of feeding. However, post infection with A. hydrophila ¢sh fed the yeast-supplemented diet resulted in a signi¢cant increase in the levels of plasmatic immunoglobulin M. Superoxide dismutase and catalase (CAT) activities were signi¢cantly higher in the yeast group. In this ¢sh, CAT and heat shock protein 70 genes were up-regulated before and after infection of A. hydrophila. The present study is the ¢rst one reporting that yeast (D. hansenii) can enhance immunity and resistance against A. hydrophila.

Comparison of the Effects of HCG and LHRHa on the Induction of Ovulation of Wild and Captive Leopard Grouper, Mycteroperca rosacea

This study was funded by the Sistema de Investigacion del Mar de Cortes (SIMAC-CONACYT 00BCS7006) and the International Foundation for Science (IFS A/3816-1). M. K. M. is the recipient of a doctoral fellowship from CONACYT.

Description of peripheral blood cells and differential blood analysis of captive female and male leopard grouper Mycteroperca rosacea as an approach for diagnosing diseases

The peripheral blood cells and differential blood profile of captive female and male leopard grouper Mycteroperca rosacea are described for aquacultural purposes. Basophilic, polychromatic, and orthochromic erythroblasts were observed as immature erythrocytes that develop into mature erythrocytes. Young erythrocytes were not evident, and bi-lobed erythrocytes were extremely scarce. Types of leukocytes included lymphocytes; three types of granulocytes (basophiles, eosinophiles, and neutrophiles); monocytes; and a specialized amoeboid-like macrophage in the blood, which has not been previously described in fish-blood literature. Thrombocytes were commonly observed. There was significantly higher erythropoiesis in males. Granulocytes and lymphocytes of females were significantly higher than males, whereas monocytes and thrombocytes were not.