Scielo RSS <![CDATA[Latin american journal of aquatic research]]> vol. 46 num. 4 lang. es <![CDATA[SciELO Logo]]> <![CDATA[Rock oyster <em>Striostrea prismatica</em> (Gray, 1825): biology, exploitation and conservation]]> ABSTRACT Oyster or rock oyster (Striostrea prismática) is a bivalve mollusk highly appreciated among traditional seafood in several Latin American countries. Uncontrolled capture and lack of techniques for its culture, threaten their growth and conservation, as a decrease in its population has been reported. This review highlights critical aspects of its biology, ecology, catching activity and potential use in aquaculture. Its presence is registered as a fossil, and its identification is crucial because of its similarity to other species of ostreids. The population structure and its abundance in natural banks are associated with depth, substrate, dynamics of exposure and local environmental conditions. The reproductive activity and gametogenesis vary from an annual increase to continuous reproduction related to its location latitude. The size at first maturity is similar in both sexes and achieves about nine cm in less than a year. In culture experiments, diets in breeding stocks have been studied, resulting in trochophore larvae and “D” larvae, at 12 and 24 h after fertilization. Shell fixation has been achieved in natural collectors, but their culture has not been developed yet. The species is used as an indicator of pollution, associated with microalgae causing harmful outcrops. There are no precise records of its catch, as it is reported in combination with other ostreids species. For its conservation and sustainable exploitation, it is necessary to increase research on its biology to implement management programs and developing culture techniques. <![CDATA[Pilot acoustic tracking study on young of the year scalloped hammerhead sharks, <em>Sphyrna lewini</em>, within a coastal nursery area in Jalisco, Mexico]]> ABSTRACT A preliminary experience to study, on a small scale, the movements of the young of the year (YOY) Sphyrna lewini (Griffith &amp; Smith, 1834), in the Mexican Central Pacific, using acoustic telemetry within a nursery area. From October to December 2014 seven sharks were tagged with ultrasonic transmitters and tracked for 68 days within a 14 km2 area associated to a river mouth. The quick shark handling allowed their release in less than two minutes and excellent health condition. Although recaptured sharks up to 105 days after tagging did not show symptoms of scar infection, a slight abrasion in the shark skin was observed after 51 days. The ultrasonic transmitter retention was 75%, and the site fidelity was complete (F = 1) during the first ninety days. For the 135-day period, fidelity was 0.63 (0.40-0.80), and the estimated attrition rate was 0.73 (0.34-1). Ninety-seven percent of detections occurred on soft bottoms and less than 30 m depth. The YOY S. lewini stayed active 24 h a day and performed estimated movements of 11.96 km during that time. The home range for all tagged sharks was estimated to be 4.82 km2 using the minimum convex polygon method (MCP) and 4.89 km2 using the kernel utilization distribution method (95% KUD). The KUD estimation showed two core areas within the study area, is the one located in front of the river mouth the most used. <![CDATA[Changes in fish assemblages caused by different Neotropical biomes]]> ABSTRACT We studied the leading causes of the spatial distribution pattern of fish species assemblage in the transition region between Cerrado-Caatinga biomes, in the São Francisco River (Brazil). Biotic and abiotic variables were collected at 17 sampling sites located in three sub-basins, in two periods during 2015. Some 1689 individual fish were sampled, distributed in 69 species, 51 genera, 22 families and seven orders. There was a low overlap of species, with only seven species in common among the three sub-basins. The most substantial degree of sharing occurred between sub-basins from the Cerrado biome, with 22 restricted species. Crenicichla lepidota, Psellogrammus kennedyi, and Hoplosternum littorale were associated with the sub-basin from Caatinga, and Astyanax aff. eigenmanniorum and Bryconops aff. affinis with Cerrado sub-basins. The fish assemblage showed significant spatial variation between biomes, and the distribution was determined by an interaction of regional altitude variable with local variables such as river width, substrate and water velocity (environmental factors), but geographical factors were also important. Fish assemblage difference along a large river course has significant implications for conservation strategies, management or evaluation of biodiversity, needing several strategies for their preservation considering small geographic areas. <![CDATA[Toxicological assessment of binary mixtures and individually of chemical compounds used in reverse osmosis desalination on <em>Artemia franciscana</em> nauplii]]> ABSTRACT The Reverse Osmosis desalination has become a technological option to guarantee an adequate drinking water supply in zones with water scarcity. Nevertheless, the process is accompanied by potential adverse impacts on the coastal ecosystem, mainly due to chemical discharges. Taking into account the environmental risk presented by these chemical mixtures, in this work we used a short-term toxicity bioassay with Artemia franciscana nauplii expressed in lethality to exposures individually and their combinations. Results showed that toxicity degree from single exposures was C5H8O2 &gt; NaClO &gt; CuSO4 &gt; KMnO4 &gt; FeCl3, indicated that C5H8O2 was the most toxic biocide. However, all compounds in combination with C5H8O2 exhibited a very strong antagonism. Except, in mixtures, NaClO/FeCl3 and CuSO4/KMnO4 resulted in an additive effect. This environmental assessment will allow reducing risk significantly on the concentrate considering the sensitivity of the marine ecosystem to the application of chemical agents during the desalination process. <![CDATA[Mollusk freaks: new teratological cases on marine mollusks from the South Pacific Ocean]]> ABSTRACT The present study provides new documented cases of abnormalities on chitons (hypomerism and coalescence of shell plates), in addition to four new cases on keyhole limpets (closed apical opening), and one new teratologic case on internal organs in octopuses (missing gill). We assess the frequency of these abnormalities and discuss about its possible environmental, mechanic and genetic causes. Several of these findings represent the first of these cases reported in South Pacific Ocean. <![CDATA[Bycatch of the Isla del Rosario (Gulf of Salamanca, Colombian Caribbean) artisanal shrimp fishery in an approximation to the biodiversity impact]]> ABSTRACT In the period March 2009-February 2010 the fish bycatch of the artisanal shrimp fishery operating off the beach of Isla del Rosario (Gulf of Salamanca, Colombian Caribbean) was evaluated and length-frequency data analysis were done for five of the main ichthyic species. For this purpose, data registered in the project “Pesca artesanal del Magdalena”, processed in the Fisheries Information System of Invemar (SIPEIN) to obtain fishery variables, on a monthly basis, was used. Between shrimp and fish fauna 38,265 kg were registered. The ichthyic bycatch fauna was composed of 59 fish species, distributed in 23 families, being Engraulidae, Sciaenidae, and Mugilidae the most representative. Regarding the engraulid Cetengraulis edentulus biomass, it was the most important species. Ichthyic bycatch to shrimp relationship was 1.2:1.0 with shrimp beach seine. During the assessed year, the highest mean Landing Per Unit Effort (LPUE) was present in the dry season, but November (rainy season) was the month with the highest shrimp LPUE. The indicators, Lc (mean length) and spawning/juvenile proportion, evidence growth overfishing for the species Bairdiella ronchus, Cathorops mapale, Mugil incilis and Trichiurus lepturus. The state of this fishery and the impact it generates on the ecosystem is discussed. Measures for its proper management are recommended. <![CDATA[Reproductive biology of the leopard grouper <em>Mycteroperca rosacea</em> (Streets, 1877) in the coastal area of Santa Rosalía, BCS, Mexico]]> ABSTRACT 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 year-round 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 Rosalía, 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 &lt; 0.05). Population size at first maturity (L50) 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 20-23°C). 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. <![CDATA[Nutrients and bioactive compounds of the <em>Lemna gibba</em> and <em>Ulva lactuca</em> as possible ingredients to functional foods]]> ABSTRACT Lemna gibba freshwater macrophyte and seaweeds Ulva lactuca of the middle basin Papaloapan River, southeast of Mexico were chemically characterized in their nutrients and bioactive compounds for possible use in the formulation of functional foods. The proximate chemical analysis showed that ashes contents (g 100 g−1 sample) of L. gibba and U. lactuca were 20.10 and 33.07, crude protein 21.5 and 17.2, lipids 4.45 and 1.7, nitrogen-free extract 32.4 and 38.34, respectively. Significant differences (P &lt; 0.05) were found in the chemical composition between the two species of aquatic plants. L. gibba resulted in a protein source, and U. lactuca resulted in an energy source. They had eight essential amino acids for fish and other aquatic species and were abundant in lysine and methionine. Both aquatic plants had an essential quantity of inulin (functional fiber) this data not been reported. Also, they had xanthophyll and variety of antioxidant (β-carotenes, lutein, lycopene and neoxanthin). L gibba had only had one polyunsaturated fatty acid (PUFA; α-linolenic (ALA) 30.31 mg g−1). U. lactuca had a variety of essential PUFA's (ALA, LA, AA; 3.93, 6.73 and 0.41 mg g−1 of fatty acids, respectively). Based on these results, both of the aquatic plants of the middle basin Papaloapan River studied are susceptible to take advantage in the formulation of functional food, since according to the literature the compounds identified have shown beneficial effects as immunonutrients, immunostimulants, antioxidants or modulators of intestinal flora. In aquaculture production, it is suggested to prove the combined use of these two plants as functional ingredients or some particular component in the diets as prevention strategy of diseases as well as to promote aquaculture sustainable through the use of these plants in the productions. <![CDATA[Comparison of catch, CPUE and length distribution of spawning aggregations of mutton snapper (<em>Lutjanus analis</em>) and grey triggerfish (<em>Balistes capriscus</em>) on a Mesoamerican coral reef]]> ABSTRACT This study evaluates the habitat characteristics, fishing effort, and production, as well as changes in the individuals, such as changes in size frequency, of the spawning aggregations of mutton snapper Lutjanus analis and grey triggerfish Balistes capriscus, caught in the Chinchorro Bank Biosphere Reserve (CBBR), Mexico. The mutton snapper aggregation was located in coral patches, while the spawning aggregation of grey triggerfish was located on the windward terrace of the reef flat. Fishery data was obtained for the duration of the spawning event in 2008, with a total of 5 days for mutton snapper and 4 days for grey triggerfish. The fishery recorded a total of 830 mutton snappers, with individual sizes ranging from 40 to 77 cm in fork length (FL). Individual size and catch per unit effort (CPUE) decreased through time, with the lowest values presented at the end of the 5 days. In contrast, a total of 665 grey triggerfish were recorded in the catch, ranging from 45 to 61 cm (FL) with the largest sizes caught at the end of the fishing period, concurrently with the lowest CPUE. A lack of governance allowed both species to be harvested during their spawning aggregations. The creation of an international body composed of fishers, managers, conservationists, and scientists from the countries belonging to the Mesoamerican Reef System is urgently required to look for agreements in conservation and management strategies of these commercially important species. <![CDATA[Spatio-temporal distribution of four commercial shrimp species in the southeastern Gulf of California, Mexico]]> ABSTRACT The shrimp trawl fishery in the southeastern Gulf of California is one of the most important in Mexico due to the high economic value of the resource in the national and international market. The management of this fishery is based on permits, a no-trawling zone, a no-fishing season and regulations of fishing gears. In order to analyze the efficiency of the no-fishing season and the viability of a spatial closure, we analyzed the distribution and size structure of four species targeted by the commercial fishery during the 2005-2006 shrimpfishing season, the white shrimp (Penaeus vannamei), blue shrimp (P. stylirostris), brown shrimp (P. californiensis) and crystal shrimp (P. brevirostris). We found that the size distribution of four shrimp species was wide and with variable frequency during the fishing season. The average biomass for each species was different throughout the fishing season, and the white and brown shrimps were the most abundant species. However, the spatial distribution of the biomass was similar for the four species. Our results suggest that the nofishing season is more effective for brown shrimp because the individuals caught by the fishing gear have already reproduced at least once. <![CDATA[Morphometric relationships and growth models for the oyster <em>Crassostrea corteziensis</em> cultivated at the southeastern coast of the Gulf of California, Mexico]]> ABSTRACT This study aimed to determine weight-size relationships and to fit the best growth model of the Cortez oyster Crassostrea corteziensis from early juvenile to adult during one single culture cycle. The morphometric data (n = 50 oysters sampled each two weeks during January 2010 to March 2011) of shell height-shell length [SH-SL], shell height-shell width [SH-SW], shell width-shell length [SW-SL], body weight-shell length [BW-SL], body weight-shell height [BW-SH] and body weight-shell-width [BW-SW] (log-transformed) were determined by regression analysis. The SL and SH measurements (R2 = 0.98) were consistently proportional to the BW, being the BW-SL and BW-SH morphometric relationships the more suitable for growth evaluation of C. corteziensis in culture. Four different equations of the Schnute model, as well as Special cases 1 and 2 (equivalent to the Von Bertalanffy growth model, VBGM, and Logistic models, respectively), were evaluated utilizing length-at-age data to estimate individual growth parameters. The parameters were obtained using the maximum likelihood algorithm and the Akaike information criterion was applied to rank the models examined. The growth curve displayed a rapid increase until the size of 41.68 ± 16.18 mm in length. In the present study, the symmetrical sigmoid curve was the best hypothesis that fit the data; however, it is assumed that the age data are sufficiently informative to describe the growth pattern of C. corteziensis, with either Schnute model Special case 2. Results from morphometry and growth model in this study represent useful tools to analyze growth performance of the Cortez oyster in culture better. <![CDATA[Records of bycatch of <em>Hippocampus patagonicus</em> (Pisces: Syngnathidae) in commercial fishing in southern Brazil]]> ABSTRACT Hippocampus patagonicus is classified as endangered in the vulnerable category by Brazilian law (MMA, 2014), and by IUCN (International Union for Conservation of Nature) criteria. Thirteen boats from the commercial fishing fleet of southern Brazil were monitored for 17 months to supplement data for the evaluation of this species. Three seahorse collection points were established, where the fish are landed: port of Imbé/Tramandaí and port of Passo de Torres (northern coast (NC) of Rio Grande do Sul) and the port of Rio Grande (southern coast (SC) of Rio Grande do Sul). The presence of H. patagonicus was recurrent, and the collected animals were between 22 and 130 mm in height. The species was captured from 11 to 57 m deep as bycatch of significant transboundary marine resources (Brazil, Uruguay, and Argentine). In bycatch of gillnet fishing (NC), estimated capture was 0.68 ± 0.97 seahorses/month/vessel, annually, an average of 89.76 seahorses would be removed from the sea by the 11 vessels involved. In trawling (SC), it was 49.66 ± 64.86 seahorses/month/double-rig trawl. It is estimated that 8,342 seahorses are removed annually as bycatch, only in this mode of fishing. The information obtained reinforces the need to apply ecosystem management to fisheries for the recovery of stocks that are over-exploited and accompanying fauna as well, especially small species with poorly known life histories such as H. patagonicus. <![CDATA[Immune-related gene expression in <em>Penaeus vannamei</em> fed <em>Aloe vera</em>]]> ABSTRACT The immune response is critical in cultured shrimp facing pathogens that are serious concerns. Therefore, immune-related gene expression was investigated in Penaeus vannamei fed with Aloe vera. Shrimp weighing 2.9 ± 0.8 g were fed with 1 g of A. vera kg feed−1. Six shrimp were sampled at 0, 6, 12, 24, 48, and 72 h for gene expression. Samples of time zero were taken just before feeding with aloe. After feeding with aloe during 24 h, uneaten food and waste material were removed and then shrimp were fed only with commercial feed. Quantitative real-time PCR measured time series expression of four genes (translationally controlled tumor protein [TCTP], superoxide dismutase [SOD], heat shock protein 70 [HSP70], and penaeidin4). The expression of TCTP was down-regulated, and the expression of SOD, HSP70, and penaeidin4 was up-regulated. This is the first report showing the effect of A. vera on the modulation of shrimp immune response. The immunostimulant properties of A. vera could be useful for cultured shrimp health. <![CDATA[The offshore recreational fisheries of northeastern Brazil]]> ABSTRACT This study was carried out to estimate total catches extracted from the offshore areas of northeastern Brazil by recreational fishers from offshore operations, daily activities, and fishing competitions. It also aimed at providing a first estimate of expenditure by anglers in the region. The basis for this analysis was the data supplied by the only offshore fishing operator established in Paraíba State. The available logbooks allowed for the first estimate of total catches by anglers in Paraíba State, which was extrapolated to the entire region using information provided in a database of recreational fishers’ licenses. By combining these data with catch data from fishing competitions, we were able to estimate that a peak of about 90 t was extracted in 2011. This catch is low when compared with commercial catches, but the associated economic impacts, assessed via the expenditure by recreational fishers at US$1.5 million in 2014, is high. Moreover, catches are concentrated mainly on a small number of species, mostly Thunnus spp. and Seriola spp. in waters off Paraíba State. No information is available on the current status of these amberjacks (Seriola spp.). However, some of the snappers (Fam. Lutjanidae) included in the top species caught by recreational fishers are considered overexploited in the region. <![CDATA[Detecting <em>Opisthonema libertate</em> (Günther, 1867) phenotypic stocks in northwestern coast of Mexico using geometric morphometrics based on body and otolith shape]]> ABSTRACT Stock discrimination is essential for biomass population assessment and essential for the fisheries management. The analysis of shape differences in anatomical structures (e.g., body shape, otoliths, scales) has been relevant issue in the study of population structure. We evaluated the hypothesis on the existence of a stock-structured population of Pacific thread herring Opisthonema libertate in the northwestern coast of Mexico. Geometric morphometric methods were used to analyze body and otolith shape. Samples come from at three commercial fishery-landing sites: Magdalena Bay, Guaymas, and Mazatlan, Mexico. Results based on body and otolith shape support the existence of different morphotypes by location. Body shape allowed better discrimination than otolith shape. The differences observed between the phenotypic stocks suggest seasonal movements, which are linked to the marine current system in this region, particularly to the California Current and the North Equatorial Counter Current. <![CDATA[Evaluation of potential confounding factors in sediment toxicity tests with <em>Hyalella azteca</em> (Saussure, 1858)]]> ABSTRACT Ecotoxicological tests performed in waters with low salinities, typical of estuarine environments, are limited regarding the availability of test organisms. The amphipod Hyalella azteca, an organism protocoled for trials with freshwater sediments, presents a potential for use in saltwater tests in which the confounding factors, such as salinity and sediment grain size, should be evaluated to avoid errors in the results in relation to the sensitivity of the organism. Thus, amphipod cultivations in salinities of 0, 5, 10 and 20 were conducted, to perform tests of tolerance to salinity, and sensitivity to a reference toxicant. The tolerance of the species to different sediment grain sizes and organic matter contents was evaluated in tests with reconstituted sediments in five different compositions, varying the content of organic matter (5 to 20%), clay and sand (0 to 95%). The results of the cultivations showed that animals maintained present the best reproduction and survival rates at salinity 5, and a tolerance limit under chronic conditions, at salinity above 10. The salinity can be considered a confounding factor since the tests carried out with the reference toxicant showed the higher resistance of the species under conditions of higher salinities. The species present tolerance to different sediment grain sizes and organic matter contents; therefore, this factor does not interfere in the survival of H. azteca during the ecotoxicological tests. <![CDATA[Quantifying the morphology of key species caught in the southern Brazilian penaeid-trawl fishery as a precursor to improving selection]]> ABSTRACT Penaeid trawls are poorly selective fishing gears; contributing towards approximately 27% of global marine fisheries discards. Various options are available for mitigating penaeid-trawl bycatch, including gear modifications such as ‘bycatch reduction devices’ (BRDs) or codend mesh-size regulations. A precursor to developing modifications is information about the key target and bycatch species in terms of their sizes and morphology. Here we describe the relationships between these characteristics for the southern Brazilian industrial penaeid-trawl fishery within a broader objective of proposing more selective trawl configurations. Catches were sampled during 37 tows. Fifty-two species were caught, including two loggerhead turtles, Caretta caretta, one green turtle, Chelonia mydas, as well as 61 individuals of seven ray species classified as Endangered or Critically Endangered. One penaeid (Pleoticus muelleri) and 11 teleosts were assessed for various morphological relationships. The data demonstrated that both the existing conventionally used 26 mm (stretched mesh opening; SMO) mesh and a legislated size of 30 mm SMO are too small. Using morphological relationships, we propose testing a minimum diamond-shaped mesh size of at least 35 mm and a square-mesh window in the top of the codend comprising at least 48 mm mesh. Such a configuration would probably retain penaeids and larger teleosts, but allow many small teleosts to escape. Anteriorly located grids are also required to reduce the bycatch of charismatic species like turtles and rays. Wide-scale use of such BRDs should considerably reduce bycatches and the ancillary impacts of regional penaeid-trawl fisheries. <![CDATA[Feeding habits of the mojarras (Gerreidae) population in the hyperhaline lagoon system of Ría Lagartos, Yucatan, Mexico]]> ABSTRACT The trophic preferences and ontogenic variations were evaluated and compared between five species of mojarras collected bimonthly for two years (2004-2005) in the hyperhaline lagoon system of Ría Lagartos, Yucatan Peninsula. A total of 361 specimens corresponding to Eucinostomus argenteus, Eucinostomus gula, Eucinostomus harengulus, Eugerres plumieri and Diapterus auratus were collected and used for trophic analysis. The trophic components were analyzed using the Relative Importance Index (RII) and multivariate analysis. The mojarras were defined as second-order consumers, feeding on microcrustaceans (amphipods, copepods, tanaidaceous, ostracods) and significant amounts of detritus with variations in the proportion and frequency of different types of food according to their ontogeny and food availability. Three species shared the same resources. However, differences were observed at the general and ontogenetic level, avoiding inter and intraspecific competition. Results provide evidence of the importance of these coastal habitats for the trophic requirements of marine-euryhaline juvenile fish species. <![CDATA[The larval development from prezoea to megalopa and juvenile stages of <em>Allopetrolisthes punctatus</em> (Guérin, 1835) (Decapoda, Anomura, Porcellanidae)]]> ABSTRACT The external morphology of the larval steps in the development of the Anomuran crab Allopetrolisthes punctatus is described using material obtained under laboratory conditions and from field samples. All stages are presented with photos taken with a scanning electron microscope. For the first time in this species, and in a similar way as described for the whole family Porcellanidae, it was possible to identify one prezoea, two zoeal and one megalopa stages. The main difference between the zoeal stages is the translucid spine in the center of the telson of the zoea II, surrounded by five gross setae at each side. Also, we also studied first juvenile stages to know the size at which sexual pleopods appear, which in our samples it occurred at 1.97 mm of carapace length. <![CDATA[DL-carnitine as supplementary levocarnitine source in plant-based diets to Nile tilapia (<em>Oreochromis niloticus</em>) fingerlings]]> ABSTRACT The objective was to evaluate the effect of DL-carnitine levels on the growth and whole body and muscle composition of Nile tilapia fingerlings. A basal plant-based diet was supplemented with 0, 500, 1000, 1500, 2000, 3000 and 4000 mg kg−1 of DL-carnitine hydrochloride in a completely randomized design (n = 3). Fish (initial weight 0.8 ± 0.01 g) was hand-feed daily into three meals until apparent satiety for 70 days. The growth parameters were not influenced (P &gt; 0.05) by dietary DL-carnitine levels. Muscle lipid decreased (P &lt; 0.05) in fish fed with diets supplemented with 3000 and 4000 mg kg−1 of DL-carnitine, but there was no effect (P &gt; 0.05) on whole body lipid. These results with DL-carnitine is similar to other studies using pure L-carnitine. Thus, the use of DL-carnitine as a source of levocarnitine in Nile tilapia diets require future studies. <![CDATA[Size and relative condition index of the brown sea cucumber <em>Isostichopus fuscus</em> in the northern Gulf of California, Mexico]]> ABSTRACT The brown sea cucumber Isostichopus fuscus is the most important commercial holothurian in the eastern Pacific, and its high market value caused overfishing and sharp declines of its populations and catches in several Latin American countries. In Mexico, the fishery has been intense in the northern Gulf of California since the 1990s, and it is currently under strong regulation. To evaluate the current status of the organisms, we measured the size, weight and estimated the relative condition index (Kn) of 702 specimens sampled in 86 rocky reefs of that region in 2016, at depths from 3 to 22 m. Mean length ± SD was 22.32 ± 5.23 cm, lower than average in the northern Gulf, but nevertheless, the average weight was 420.61 ± 192.48 g, among the highest recorded in the eastern Pacific; this is presumably due to the high primary production of the region that favors the presence of well-nourished organisms. The weight (W)-length (L) relationship was W = 3.27 L1.56, and condition index ranged from 0.045 to 2.13 (mean Kn = 0.96 ± 0.29), a figure that did not differ to that reported along the Mexican Pacific. There were differences in the value of Kn among sites, being higher in areas that are subject to the low fishing effort. <![CDATA[Occurrence and diversity of yeast species isolated from fish feed and tambatinga gut]]> ABSTRACT The present study aimed to identify yeasts species isolated from fish feed and the intestinal tracts of tambatinga fish (Colossoma macropomum × Piaractus brachypomum) cultivated in a Brazilian fish farm. Twenty tambatingas and 30 fish feed samples from different brands were acquired from two commercial establishments in the state of Piauí, Brazil. The sampled guts were divided into three equal parts, namely the anterior, medium and posterior portions, totaling 60 samples. Molecular identification was performed by PCR amplification and sequencing of the D1/D2 regions of the large rRNA subunit gene. Sixteen Candida nivariensis strains in the gut were identified. The fish feed samples showed a higher variability of yeast species, with the following species isolated: Hyphopichia burtonii (23.08%), Lodderomyces elongisporus (15.39%) and Trichosporon asahii (15.39%), Candida nivariensis (7.69%), C. orthopsilosis (7.69%), C. parapsilosis (7.69%), Rhodotorula minuta (7.69%), Sterigmatomyces elviae (7.69%), Cryptococcus liquefaciens (7.69%). Yeast found in feed, however, was not always isolated from tambatinga gut. Molecular identification allowed for the isolation of yeast species not previously reported in fish feed and gut samples. <![CDATA[Histopathological changes induced by <em>Caligus rogercresseyi</em> in rainbow trout <em>(Oncorhynchus mykiss)</em>]]> ABSTRACT The purpose of this study was to characterize histopathological changes induced by the sea louse Caligus rogercresseyi in juvenile individuals of rainbow trout (Oncorhynchus mykiss). Specific effects were determined for mucus-secreting cells, mast cells/eosinophilic granule cells (MCs/EGCs) and activation of pro-inflammatory caspase-1, which are involved in the inflammatory response. As expected, C. rogercresseyi eroded the skin to varying degrees, with increased mucus-secreting cells in the epidermis and melanophores in the dermis. Gill responses included epithelial hyperplasia, secondary lamellae fusion, an increased quantity of mucus-secreting cells in the epithelium, and MCs/EGCs in the connective tissue. Other histological changes included abundant MCs/EGCs and secretory cells in the intestine, as well as numerous melano-macrophage centres in head kidney stroma cells. Finally, the observed inflammatory response was associated with active caspase-1 detection in the gills, but not in the other assessed organs. In conclusion, C. rogercresseyi induced significant histopathological alterations in O. mykiss skin and gills and minor histological changes in the intestine and head kidney, which may reflect the overall inflammatory response of rainbow trout to infestation with sea lice. <![CDATA[First report of nutritional quality of the native fish <em>Dormitator latifrons</em> (Richardson, 1844) (Perciformes: Eleotridae)]]> ABSTRACT The native fish Dormitator latifrons, also known as chame, popoyote, puyeque and Pacific fat sleeper, grows in brackish environments in estuaries of the American Pacific coast, from Baja California (Mexico) to Perú. It is consumed regionally, and its characteristics under culture conditions are currently being evaluated. This study compared the proximate composition and fatty acid profile of wild and cultured specimens of D. latifrons to determine the effect of feeding them a commercial diet for tilapia under culture conditions. The protein content of the muscle of wild fish was higher than that of cultured fish, but the total lipid content was lower. The levels of fatty acids C18:1n9 and C18:2n6 were significantly higher (P &lt; 0.05) in cultured fish, while the levels of C20:5n3 (EPA) and C22:6n3 (DHA) were significantly higher (P &lt; 0.05) in wild fish. The n3/n6 ratio was higher in wild fish. These results show that D. latifrons is a species that can be readily cultured and that quickly gets used to formula feed. However, given the fatty acid composition of this species, it is necessary to control the quality of oil in the diet. <![CDATA[Vitamin and mineral supplementation for <em>Macrobrachium rosenbergii</em> in biofloc system]]> ABSTRACT Biofloc system is an alternative to conventional aquaculture systems as it minimizes effluents, improves water quality, ensures greater biosafety due to minimal water exchanges and also serves as an additional food source for prawn. The present study aimed to evaluate the effect of suppression of vitamin and mineral supplements on diets for Macrobrachium rosenbergii reared in the biofloc system. Four experimental diets were evaluated: complete diet (Diet 1 with vitamin and mineral supplementation); diet without vitamin supplement (Diet 2); diet without mineral supplement (Diet 3) and diet without vitamin and mineral supplement (Diet 4). The experimental design was completely randomized with four replicates per treatment. After 45 days of trial survival rates above 90% and feed conversion rate ~1.83 were observed for all treatments, indicating that the production of M. rosenbergii in the biofloc system does not require the inclusion of vitamin and mineral supplementation in the feed.