Scielo RSS <![CDATA[Latin american journal of aquatic research]]> http://www.scielo.cl/rss.php?pid=0718-560X20200001&lang=en vol. 48 num. 1 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[Morphometric comparison of the growth curve in Nile tilapia (<em>Oreochromis niloticus</em>) sexually reverted to masculinized and feminized]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100001&lng=en&nrm=iso&tlng=en ABSTRACT Aquaculture is an industry in development around the world that allows covering the nutritional demand with a high nutritional value. Within this industry, monosex crops of some species, such as the Nile tilapia (Oreochromis niloticus), stand out. In this study, the effect of the administration of 17α-ethinyl estradiol and 17α-methyltestosterone on the morphometry of Nile tilapia at different times was evaluated. Nile tilapia were raised under controlled conditions and divided into three groups: control: no hormone treatment; feminized: treated with 17α-ethynyl estradiol and masculinized: treated with 17α-methyltestosterone. The measurements were made at 5, 10, 15, 25, 35, 40, 50, 60 and 70 days after fertilization with the morphometric technique “truss protocol.” The data were analyzed using a general linear model of repeated measurements and analysis of variance of comparison of means. The growth curve was made using the Gompertz logistic model. The results showed that the masculinized larva presented a higher growth rate and increased daily gain of weight 2.05-2 mg compared to the controls and feminized 1.67-3 mg and 7.57-4 mg, respectively. The sexual reversion of Nile tilapia with 17 α-methyltestosterone increases the growth curve of the masculinized organism and the uniformity of the final size. <![CDATA[The effect of tilapia <em>Oreochromis niloticus</em> addition on the sediment of brackish low-salinity ponds to white shrimp <em>Penaeus vannamei</em> farming system during the wet and dry season]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100007&lng=en&nrm=iso&tlng=en ABSTRACT The present study was carried out to determine the effect of tilapia Oreochromis niloticus on the physical and chemical sediment parameters on an earthen pond in monoculture (shrimp Penaeus vannamei) and co-culture (tilapia-shrimp) during the dry and wet seasons in a commercial farm during the period from mid-September to end-December 2017 and February to mid-May 2018. Chemical and physical analyses were realized on sediment samples from brackish water ponds representing shrimp farms in San Blas Nayarit, Mexico. Concentrations of organic carbon, nitrogen, potassium, magnesium and calcium were higher in co-culture ponds, and there was a tendency to a higher concentration of phosphorus and sodium in the sediment of monoculture ponds. The texture of the ponds showed a tendency in the dry season to increase the percentage of clay in co-culture due to the effect of bioturbation caused by tilapia. There was no evidence of poor development of sediment quality in any treatment. It was found that tilapia was a factor that affected sediment quality, differences in growth between shrimp monoculture and tilapia-shrimp co-culture can be explained, at least in part, by differences in their sediment. <![CDATA[Age and growth of thread herring <em>Opisthonema libertate</em>, in the southern Gulf of California]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100015&lng=en&nrm=iso&tlng=en ABSTRACT To fit a growth model to Opisthonema libertate, the most common thread herring in a small pelagic fishery in the southern Gulf of California, size data of commercial landings and age were generated from sagittal otoliths assessed during three different years, 2005, 2008 and 2015, representing Neutral, La Niña and El Niño environmental conditions, respectively. A multimodel select approach on five special submodels of generalized Schnute model, including one, equivalent to the Von Bertalanffy model, were used. A total of 573 otoliths were analyzed; 219 from Neutral, 149 from El Niño and 205 from The Niña events. An opaque zone of otoliths formed in winter-spring when chlorophyll a (Chl-a) concentrations were at a maximum. However, a hyaline zone of otoliths formed during the summer of the reproductive period. Schnute submodel 1 was the best model selected in all three environmental conditions, but submodel 3 was the best on pooled data. Length of thread herring aged 0.5 years old in the El Niño year was lower than other environmental-years analyzed. A possible compensatory effect on growth with age was observed in the data because environmental conditions affected the growth of 0.5-year-old thread herring, as was evident in size variance in this age group under all three conditions, but variance decreased in the older age groups. Thus, a multimodel average of Schnute submodels 1 and 3 could be used to describe the growth of O. libertate in the southern Gulf of California. <![CDATA[The influence of habitat on the spatio-temporal dynamics of fish assemblages in a lagoon-estuarine system of the Mexican Pacific]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100023&lng=en&nrm=iso&tlng=en ABSTRACT Fish assemblages change significantly with physical and chemical characteristics of water; however, their response to the variability of geomorphic habitats has been rarely evaluated in lagoon-estuarine in one of these systems of the Mexican Pacific. Spatio-temporal variation of fish assemblage structure was assessed for three habitats: lagoon, estuarine, channel and inlet. The hypothesis was that sheltered areas support comparatively higher richness and abundance of fish species, with more small-sized specimens than the most exposed areas. We found that the ichthyofauna differed significantly among habitats. Several species were smaller in the lagoon compared with the other habitats, suggesting a use of the lagoon as a nursery ground. Moreover, dominant species for the lagoon were rarely found or absent in the inlet, whereas others were found only present or with higher abundance in the inlet. Although seasonal differences in richness and composition were detected, the evidence of fish-habitat associations for many species was noticeable regardless of seasonality, probably due to a high percentage of resident species during the annual cycle. The lagoon supports a greater abundance and species richness, due to a more sheltered and structured habitat, evidencing habitat-driven segregation in fish assemblages, and an aspect that should be incorporated for management of coastal ecosystems. <![CDATA[Effect of size grading on the growth of pirarucu <em>Arapaima gigas</em> reared in earthen ponds]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100038&lng=en&nrm=iso&tlng=en ABSTRACT Size grading is a common management practice in fish farming to minimize growth variability. Such practice has not been established for pirarucu Arapaima gigas. Therefore, the present study assessed the effect of size grading on the growth of pirarucu. Juvenile pirarucu were divided into three groups: ungraded fish (U: mean initial weight 1.12 kg), small fish (S: mean initial weight 0.81 kg), and large fish (L: mean initial weight 1.36 kg), and reared for 129 days (phase I) and 158 additional days (phase II), consecutively. No significant difference was observed in the final length, specific growth rate, biomass, survival and feed conversion rate between fish groups. Ungraded fish presented a greater decrease in the coefficient of variation for weight in phase I than in phase II. Size sorting resulted in significantly higher growth after 287 days of farming in the L-graded fish (9.49 kg, final weight), followed by the ungraded group (8.80 kg) and S-graded group (8.01 kg). However, the mean weight of pooled S- and L-graded fish was similar to the ungraded fish group in phase I and phase II, indicating that grading did not improve the general performance of pirarucu in captivity. <![CDATA[Biology of <em>Hippocampus patagonicus</em> (Syngnathidae) in Brazilian waters. A species threatened with extinction, with suggestions for the conservation of seahorses in Brazil]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100047&lng=en&nrm=iso&tlng=en ABSTRACT Specimens of Hippocampus patagonicus obtained in the bycatch of trawling in the states of Rio Grande do Sul (RS) and Rio de Janeiro (RJ) were collected in 2012 (n = 199) and 2014 (n = 157), respectively. Mean height of females of reproductive age in RS was 8.89 ± 1.9 cm, with the fecundity of 366 ± 195.8 eggs per clutch, and for males of reproductive age, height was 8.79 ± 1.86 cm and weight 2.3 ± 1.67 g, with 404 ± 99 embryos at each gestation. In RJ, height was 9.69 ± 1.05 cm and weight 2.9 ± 0.9 g, with the fecundity of 277 ± 95.06 eggs per clutch, and for males, height was 10.06 ± 1.02 cm and weight 3.68 ± 1.18 g, with the fecundity of 156.38 ± 66 embryos at each gestation. The equations obtained from the weight (W) to height (H) ratio were: W = 0.002 H3.182, R2 = 0.947 (RS males); W = 0.004 H2.914, R2 = 0.949 (RS females); W = 0.0050 H2.838, R2 = 0.793 (RJ males); W = 0.014 H2.355, R2 = 0.733 (RJ females). RS females produced more eggs (P = 0.023), and males incubated more embryos (P = 0.000) than those of RJ. The mean height of brood pouch formation in males was 4.69 ± 0.48 cm, 95% CI [4.53; 4.86], while the mean height at first sexual maturity was 8.34 cm (95% CI [7.481; 9.046]). Alternative strategies need to be developed for the conservation of H. patagonicus in Brazil. <![CDATA[Reproductive traits and natural mortality of the cardinalfish <em>Epigonus crassicaudus</em>: crucial information for stock assessment and sustainable management measures]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100058&lng=en&nrm=iso&tlng=en ABSTRACT Reproductive traits and natural mortality rate of cardinalfish females (Epigonus crassicaudus) were studied from samples collected onboard commercial fishing vessels, from 2012 to 2015, on the Chilean coast. The reproductive cycles of females analyzed thought gonadosomatic index (GSI) showed a maximum reproductive activity in austral fall, between March and May. Length (L50%) and age (A50%) at maturity, estimated using a macroscopic scale of the developed ovary, was 22.3 cm fork length (FL) and 9.3 years, respectively. Natural mortality (M) was estimated by two age-related methods. Using maximum age (tmax) M was estimated in 0.063 yr-1 and through age-at-maturity (A50%) in 0.15 yr-1. A potential bias in the reproductive study is discussed when a macroscopic maturity scale is used. Nevertheless, its usefulness is validated when funding is scarce, and time is limited. Although M uncertainty was not evaluated, the estimated range appears to be into the expected values to long-lived species. The life history parameters estimated in the present study can be used to evaluate possible time variability in maturity and M rates. Also, these results could be used in stock assessment analysis and to apply effective management measures in the fishery. <![CDATA[Effect of size heterogeneity of Nile tilapia (<em>Oreochromis niloticus</em>) on the optimal harvest time: a bioeconomics approach]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100065&lng=en&nrm=iso&tlng=en ABSTRACT A critical problem in the production of Nile tilapia Oreochromis niloticus in intensive and hyper-intensive systems is the heterogeneity of body sizes as it influences the final production and economic yield. The objective of this study was to calculate the bioeconomic effect of size heterogeneity on the production of Nile tilapia at a commercial level and to determine the optimum harvest time (OHT) considering four minimum marketable sizes target (Mms = 350, 400, 450, 500 g). Two seeding strategies were evaluated: homogeneous seeding (HM) with a 96.55 ± 24.51 g initial body weight and heterogeneous seeding (HT) with a 100.17 ± 5.91 g initial weight. Fish from both treatments were stocked at 40 fish m−3 in triplicate using a randomized design. The calculated quasi-profits of variable costs showed an inversely proportional relationship with the minimum market size in both groups. The smaller size dispersion in HM generated higher profits than HT. The OHT for Mms [350, 500 g] of HM population was 180 days, with a mode of 641 g. The OHT was also 180 days for the HT population but only for the Mms [350, 400 g] and a mode of 578 g. In terms of quasi-profits, the HM produced 19.93% more quasi-profit than the HT in the market size of 350 g at 180 days (HM = 0.50 USD kg−1; HT = 0.44 USD kg−1). The simple bioeconomic model presented here can help producers manage a series of economic decisions associated with OHT, when targeting different market segments requiring different Mms. <![CDATA[Spatial and temporal differences in the fish assemblage structure in a subtropical estuary]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100074&lng=en&nrm=iso&tlng=en ABSTRACT A large number of fish species use the mangrove mainly due to food availability and protection against predators. The knowledge of temporal and spatial dynamics of ichthyofauna allows us to identify patterns of occupation of this ecosystem and to support the assessment and preservation of local biodiversity. In this sense, samplings were conducted in 1988 at five areas of the Itacorubi River estuary, Santa Catarina Island. A total of 3,883 specimens were collected, distributed in 21 families and 41 species with the predominance of Cetengraulis edentulus, Mugil liza, Mugil curema, Genidens genidens, Mugil gaimardianus, Eucinostomus gula, Micropogonias furnieri, Pomatomus saltatrix and Sphoeroides testudineus. On average, abundances differed between seasons and sampled areas. Differences were detected between the fish faunas of fall and winter compared to summer and spring and between sampling sites. This study identified a fish assemblage in the mangrove of the Itacorubi River with a similar structure to other estuaries of southern Brazil. <![CDATA[Amazon freshwater crab <em>Dilocarcinus pagei</em> (Decapoda: Trichodactylidae): a view about burrow construction behavior]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100085&lng=en&nrm=iso&tlng=en ABSTRACT Crabs use burrows to prevent predation, environmental interference and shelter. The present study investigated the excavation behavior of the trichodactylid crab Dilocarcinus pagei, considering the biometric aspects of the burrows, the excavation time, the amount of bioturbation and the excavation behavior of the two sexes. The burrows of males had a mean diameter larger than the females, although the depth was similar for both sexes. Females had higher bioturbation than males, and showed enlargement in a camera format at the bottom, even closing the entrance of the burrows with a “plug” after their construction. Both the camera and the presence of the “plug” in the burrows of the females may be associated with reproduction. The presence of pellets observed at the entrance of burrows is associated with the cleaning of the pereiopods by crabs after the excavation. The sequence of behaviors for the construction of the burrows is described in detail, contributing to the knowledge about the biology and ecology of freshwater crabs of the Amazon. <![CDATA[Interactions of small-scale fisheries in Mexico's northwest Pacific]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100094&lng=en&nrm=iso&tlng=en ABSTRACT In Mexico, as in other parts of the world, there is limited knowledge regarding the operation of small-scale fisheries. Also, there is an urgent need for the diversity of fisheries and their interactions, and the diversity of species to be analyzed on a regional level. In this study, the dynamics of the small-scale fleet operating in San Ignacio in the northwestern Pacific of the state of Baja California Sur were analyzed, recognizing the fishery's multi-species and multi-gear character and its effect on the spatial and temporal distribution of the fishing effort. The operative units (OU) approach was applied; OUs are defined as the set of associated vessels that exploit one or more target species using similar fishing gears. The information about species, gears, sites and fishing seasons was obtained from interviews with 74 fishers. The OUs identified included: diving-pen shell scallop; diving-squalid callista; diving-Pismo clam; collection-black ark; trap-barred sand bass; trap-crab; trap-lobster; cast net-shrimp; bottom net-fish; surface net-fish; bottom net-shark. The variation in the activity of each OU is related to the availability of the resources, prices of the products and official restrictions. From a management perspective, this method helps to clarify which OUs adhere to specific rules associated with their métier and others, which are less well defined since their OU characteristics are associated with their fishery level. The definition and characterization of the OU, based on the local knowledge of the fishermen, assist the design of management schemes that consider the spatial and temporal complexity of the small-scale fisheries. <![CDATA[Nematode parasites in the striped mullet (<em>Mugil cephalus</em> Linnaeus, 1758) in the southern Gulf of California]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100106&lng=en&nrm=iso&tlng=en ABSTRACT Coastal lagoons are an important component of the Gulf of California as they are considered natural ecosystems with high productivity and home to species of regional economic interest such as the striped mullet (Mugil cephalus), which, for its eating habits tends to present parasitism. The objective of the present work was to identify and determine the number of nematode parasites in the striped mullet in three lagoon systems (Navachiste, La Reforma, and Ceuta) in coastal areas of the southern Gulf of California. Thirty Mugil cephalus were randomly obtained from each of the lagoon systems. From each fish was obtained the total length, weight and condition factor (FC), next was dissected to be analyzed hepatosomatic index (HSI) and determine by direct count the prevalence, average intensity and average abundance of nematode; nematodes are identified taxonomically and molecularly. The nematode parasites found to belong to the genus Contracaecum of the family Anisakidae in all the fish sampled the parasitic prevalence was 67%. The nematode parasites found by sex indicated that 77% of the striped mullet females analyzed were parasitized, while the males presented 59%. The CF obtained was 1.17- 4.07, and the HSI ranged between 0.85 and 1.45; the average intensity for nematodes was 7.45, and the average abundance was 4.97, demonstrating that Contracaecum multipapillatum is the main nematode parasite present in all lagoon systems the southern Gulf of California. <![CDATA[Trophic ecology of hawksbill turtles (<em>Eretmochelys imbricata</em>) in Golfo Dulce, Costa Rica: integrating esophageal lavage and stable isotope (δ<sup>13</sup>C, δ<sup>15</sup>N) analysis]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100114&lng=en&nrm=iso&tlng=en ABSTRACT Hawksbill turtles (Eretmochelys imbricata), considered Critically Endangered, have several small populations in the Eastern Pacific (EP). Knowledge about their diet and habitat use can aid in developing conservation strategies and promoting population recovery in the region. Although considered a spongivore in the Caribbean, data from the EP region indicate that hawksbills consume a wide array of prey species, including angiosperms. We used two approaches to study the diet of hawksbills at Golfo Dulce, Costa Rica: oesophageal lavage and stable isotope (δ13C, δ15N) analysis of bulk skin tissue and blood plasma. Lavage samples collected from 41 turtles revealed macroalgae as the predominant diet item (Rw = 20.22), followed by sea snails and excavating worms. Stable isotope values for blood plasma from 44 turtles ranged from −23.0‰ to −15.7‰ for δ13C and 6.9‰ to 10.4‰ for δ15N, whereas values for skin tissue were −20.4‰ to −13.9‰ and 9.3‰ to 11.0‰ for δ13C and δ15N, respectively. We compared these isotope values with those of five potential prey groups (sponge, sea snail, excavating worm, mangrove, macroalgae) using a multisource stable isotope mixing model analysis in R (SIAR). Our results indicated that multiple prey resources are important for hawksbills in Golfo Dulce, where sea snails, sponges and excavating worms contributed up to 63% of the assimilated diet per individual, and mangrove and macroalgae up to 50%. These data show that hawksbills in Golfo Dulce, and perhaps the wider EP region, are omnivorous, underscoring the importance for considering alternative habitats, aside of coral reefs, for its management and restoration. <![CDATA[Some hematology and blood chemistry parameters of the Pacific fat sleeper <em>Dormitator latifrons</em> (Richardson, 1844)]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100131&lng=en&nrm=iso&tlng=en ABSTRACT Dormitator latifrons is an amphidromous fish species distributed on the Pacific coastal region from California to Peru. It has a high potential to be cultured in Mexico. However, there is very little information about its biology, physiology and culture. This research study is a contribution to the hematology and blood chemistry of this native species. Results show hematocrit values of 28%, erythrocytes 2.075×106 mm3, leukocytes 35.035×103 mm3, mean corpuscular volume 161.547 fL, NBT 0.39, glucose 51.467 mg dL−1, protein 3.936 g dL−1, albumin 1.906 g dL−1, globulin 2.391 g dL−1 and albumin/globulin ratio 0.686. <![CDATA[Anisakid nematodes prevalence in Chilean hake (<em>Merluccius gayi gayi</em>) commercialized in the city of Talca, Chile]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100136&lng=en&nrm=iso&tlng=en ABSTRACT The main objective of this work was to determine the presence of anisakid larvae in fresh Chilean hake Merluccius gayi gayi coming from the coastal area near the city of Talca, Chile, commonly commercialized by a regional fish supply center located in the same city. Flesh and viscera of 214 fish were analyzed via direct observation, and the prevalence of parasitism was calculated. The results showed a prevalence of 100% and 24.3% in viscera and flesh, respectively. Morphologic characterization of 138 randomly selected larvae was performed via diaphanization technique, observing 106 larvae of Anisakis spp., 13 larvae of Pseudoterranova spp. and 19 nematodes classified as “unidentified.” All larvae here analyzed were viable based on the spontaneous movement ability of parasites. Overall, the high prevalence of fish infected with Anisakidae larvae highlights the importance of taking early intervention actions in order to prevent the occurrence of anisakidosis in the human Chilean population; particularly critical given the current culinary preference for raw fish dishes such as ceviche and sushi, which poses a public health issue. <![CDATA[Multiple morphological abnormalities in a blue shark <em>Prionace glauca</em> (Linnaeus, 1758) embryo from the Peruvian coast, southeast Pacific]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100141&lng=en&nrm=iso&tlng=en ABSTRACT This study reports for the first time a case of multiple morphological abnormalities in a blue shark Prionace glauca embryo collected on the Peruvian coast, southeast Pacific. External exploration and radiograph picture showed duplicated parts in the cephalic region (mouths and eye sockets) and trunk anomalies (thoracic lordosis and rolled caudal fin). The duplicate face parts in a single head seen in the embryo, suggest a diprosopia anomaly. <![CDATA[First record of loggerhead sea turtles <em>Caretta caretta</em> in Sebastián Vizcaíno Bay, Baja California Peninsula, Mexico]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100146&lng=en&nrm=iso&tlng=en ABSTRACT The loggerhead sea turtle (Caretta caretta) is an endangered species which distributes around the west coast of the Baja California Peninsula. In Baja California Sur, the conservation efforts for this species were focused in the Gulf of Ulloa; however, within the Pacific coast of the Baja California Peninsula, Sebastián Vizcaíno Bay (SVB) biological active center suit the optimal conditions for the presence of loggerheads. This study aimed to investigate SVB as a potential foraging area for loggerheads. Between July and August 2018, three prospective surveys were conducted, in search of marine turtles in SVB. A total of three loggerhead turtles and one eastern Pacific green turtle (Chelonia mydas) were captured; biometric data were recorded, and organisms were classified as juveniles. This is the first report of the loggerhead sea turtles in the SVB and given the oceanographic characteristics of the bay, it is a potential foraging and development area for the species. <![CDATA[A new record of a tiger shrimp <em>Penaeus monodon</em> Fabricius, 1798 breeding female in the coast of Campeche, Mexico]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100150&lng=en&nrm=iso&tlng=en ABSTRACT The tiger shrimp Penaeus monodon is native to the Indo-West Pacific Ocean, covering the east coast of Africa, the Arabian Peninsula, Southeast Asia, Taiwan, China, the Sea of Japan, New Guinea and Australia. A new report was recorded on the capture in the wild of a female tiger shrimp P. monodon in conditions of reproductive maturity on the coast of Campeche in the Gulf of Mexico. The specimen was captured by a trawler operating near the coast of Campeche, in front of Carmen Island. The specimen was identified using dichotomous keys, additionally corroborated with analysis of the sequence of a fragment of 650 base pairs (bp) of the mitochondrial DNA (mtDNA) gene cytochrome oxidase I (COI), and compared with the sequence of P. monodon reported in GenBank. The specimen was deposited in the National Collection of Crustaceans of the Institute of Biology of the UNAM. Histological analysis of the gonads revealed that the organism was in a reproductive condition as ovaries contained oocytes in an advanced development state. The molecular data (sequenced fragments F and R) were identical with the COI sequence of P. monodon deposited in GenBank, thus confirming the presence of P. monodon from the coasts of Isla del Carmen, Campeche. <![CDATA[Intake of different food sources in the first zoeae stages of <em>Macrobrachium tenellum</em> (Decapoda: Palaemonidae)]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100156&lng=en&nrm=iso&tlng=en ABSTRACT The objective of this work was to assess the acceptance of live and inert food by Macrobrachium tenellum during the early larval stages. The larvae were obtained by collecting wild ovigerous females in the Ameca River in the State of Jalisco, Mexico. Eight treatments (diets) were used to feed the larvae: D1, control (fasting); D2, micro-pulverized food (Purina®); D3, living, newly hatched nauplii of Artemia franciscana (INVE®, Salt Lake City, Utah, USA); D4, commercial paste containing microalgae (Instant Algae Rotifer Diet®); D5, water extracted from a biofloc system; D6, cooked egg yolk; D7, newly hatched and frozen nauplii of A. franciscana (INVE®, Salt Lake City, Utah, USA); D8, nutritional supplement for shrimp larvae (Epifeed LH1®). Treatments D2, D5, D6 and D8 showed traces of food in the digestive system. The larvae did not consume D3 and D7 treatments. The diets that had more acceptance were micro-pulverized food, a nutritional supplement for shrimp larvae Epifeed® LH1, cooked egg yolk, and biofloc water. <![CDATA[The density of the bivalve <em>Spondylus limbatus</em> in Agua Verde-Tembabiche Gulf of California, Mexico]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2020000100162&lng=en&nrm=iso&tlng=en ABSTRACT This study estimated the population density of Spondylus limbatus at six fishing banks that are representative of the Gulf of California, Mexico. Each bank was identified in July 2011. There were significant differences in density between banks, and a steady north-to-south decrease in density that was fitted to a potential model. At low densities, S. limbatus showed a lower variability in size. Since the densities of S. limbatus are suitable for commercial exploitation, sustainable extraction can be performed under a population recovery approach. Also, this study represents a baseline for the evaluation and monitoring of populations of this species through time and contributes to set general guidelines for the assessment of commercial feasibility and exploitation criteria.