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The natural spawning and scaling-up the larval rearing of yellowtail snapper (Ocyurus chrysurus) are described. We obtained fertilized eggs via the volitional spawning of broodstock acclimated for two years in two 12-m3 tanks. Of the eggs collected 10 to 14 h after spawning, 87.3% were floating, and 90% of these were transparent and presented a live embryo (egg diameter of 824 ± 77 μm and oil droplet diameter of 137 ± 14 μm). The incubation period was 18 h at 27 °C and 38 g l−1 salinity. The average normal larvae hatching rate was 88.3 ± 3.3%, and the notochord length of the newly hatched larvae was 2.5 ± 0.5 mm. Larval survival at 48-h post-hatching was 48.1 ± 3.7%. The initial mean stocking density in the 2500 l rearing tanks was 206.3 ± 24.5 floating eggs l−1, which resulted in 99 ± 43 larvae l−1 per tank. A total of 261,736 juveniles were harvested at a mean of 50 ± 3 days post-hatching (dph) from ten 4.5-m3 cylindrical fibreglass tanks, which presented a mean of 26,174 ± 3211 juveniles per tank (5.8 ± 0.7 juveniles l−1). The mean survival in the ten tanks was 7.0 ± 1.4% from the time of hatching and 15.0 ± 2.9% as of the first feeding (48-h post-hatching). Two critical periods with high larval mortality occurred during rearing: between 4 and 7 dph and during the third and fourth weeks (20–28 dph). At harvest, the mean total length (TL) was 3.8 ± 0.2 cm (range: 2.9–5.4 cm) and the mean total weight was 0.9 ± 0.2 g (range: 0.3–2.1 g). Larval growth increased from a mean of 0.24 mm day−1 during the first 14 dph (specific growth rate (SGR) of 6.7% day−1) to a mean of 1.73 mm day−1 (SGR of 9.6% day−1) in the subsequent 21 rearing days. The mean final biomass was 4.9 ± 1.3 kg m−3. Finally, the results and current and future larval rearing practices for this species are discussed.

"A total of 300 Centropomus undecimalis juveniles, with an average initial weight of 3.16 ± 0.28 g and average total length of 7.17 ± 0.22 cm, were reared for eight weeks using a recirculating system to determine the dietary protein requirement for their growth and survival. The effect of five experimental diets containing 40, 45, 50, 55 and 60% total protein content and two salinities (brackish water, BW at 5 UPS and marine water, MW at 36 UPS) were assessed. Fish were fed five times per day at 2.5% of total biomass. All treatments were performed in triplicate, recording the individual weight and total length every 15 d, while weight gain and daily growth rate were recorded at the end of the experiment. Mean weight increased proportionally as protein content increased, with the greatest growth occurring with a 60% protein diet for fish reared in brackish water, and 55% for fish in marine water. We consider that the protein requirement in C. undecimalis juveniles is high; in addition, it differs depending on the salinity, which may be due to the higher energy expenditure derived from the processes of osmoregulation in fish reared in marine water."

Se evaluaron tres alimentos balanceados en la engorda de juveniles de pargo lunarejo, Lutjanus guttatus en Nayarit, Mexico. Los efectos de los alimentos para camaron, jurel y lubina fueron evaluados a traves de la tasa de crecimiento especifico (TCE) y la tasa de conversion alimenticia (TCA) en experimentos durante 60 dias. Se utilizaron 120 juveniles en tinas de 150 L (4 por tipo de alimento) en una densidad de 10 org/tanque. La longitud patron de los animales al inicio del experimento fue de 16.7 ± 0.68, 16.8 ± 1.14, 16.4 ± 1.19 cm para los animales alimentados con piensos para camaron, jurel y lubina, respectivamente. Los pesos iniciales de estos individuos fueron de 119.1 ± 18.56, 115.5 ± 21.29 y 87.4 + 21 g/animal, respectivamente. La TCE y la TCA fueron afectadas por el tipo de alimento, observandose los valores mas altos de TCE para los animales alimentados con el alimento de lubina (1.02% g/dia; 1.4:1, respectivamente) y los mas bajos de TCE para los alimentados con alimento para camaron (0.45% g/dia; 2.5:1, respectivamente). Un valor intermedio fue registrado en los animales alimentados con el alimento disenado para jurel (0.5% g/dia) con un valor alto de la TCA de 4.43:1. No se observo una relacion entre las variables fisico-quimicas medidas y el tipo de alimento experimental, por lo que se pudo concluir que las condiciones experimentales fueron similares en todos los tratamientos. Asi, los resultados obtenidos permiten recomendar el uso de alimento para lubina como una alternativa para la alimentacion de Lutjanus guttatus bajo las condiciones de cultivo utilizadas en este estudio

The preferred temperature of Tegula regina was determined in a horizontal thermal gradient with organisms acclimated to 16C, 19C, and 22C using to acute method, with a preferred temperature of 19.7± 1.8C for the day cycle and 18.8± 1.2C for the night cycle. The final preferred temperature determined for marine snails was 19.2 ± 1.5C. The displacement velocity decreased to an interval from 99.1 cm/h to 62.5 cm/h. During the third hour, when organisms detected the preferred temperature, the velocity diminished gradually from 25.8 cm/h to 7.5 cm/h. Critical temperature maxima (CTMax), which refers to the temperature at which at least 50% of the experimental group displays a loss of attachment, was measured at three acclimation temperatures (16C, 19C, and 22C). At the acclimation temperature (16C), 50% of the experimental group had an attachment loss at a CTMax of 29.3C. At a warmer acclimation temperature (22C), the observed CTMax was 31.2C. Marine snail oxygen consumption rate increased significantly (P < 0.05, 31%) from 16 Ct o 22C.

The thermoregulatory behavior of sea hare Aplysia californica was determined in a horizontal thermal gradient; with a preferred temperature (PT) of 18.3°C for the day cycle and 20.8°C for the night cycle. The displacement velocity demonstrated an initial rate of 30 cm·hˉ1 and gradually the velocity diminished to 18 cm·hˉ1 with several fluctuations mainly at 02:00 am. Critical Temperature Maxima (CTMax refers to the temperature point where at least 50% of the experimental group have a loss of attachment) was measured at three acclimation temperatures (16°C, 19°C and 22°C). At the lowest acclimation temperature (16°C), 50% of the experimental group had an attachment loss at CTMax 32.7°C, and in a higher acclimation temperature (22°C) CTMax was 36.2°C. The Oxygen Consumption Rate (OCR) was closely correlated to acclimation temperature, and at 16°C and 19°C sea hare had a relatively stable metabolic rate, with OCR increasing to 9 mg O2 hˉ1·kgˉ1 w.w. in a higher acclimation temperature.

"Se evaluaron tres alimentos balanceados en la engorda de juveniles de pargo lunarejo, Lutjanus guttatus en Nayarit, México. Los efectos de los alimentos para camarón, jurel y lubina fueron evaluados a través de la tasa de crecimiento específico (TCE) y la tasa de conversión alimenticia (TCA) en experimentos durante 60 días. Se utilizaron 120 juveniles en tinas de 150 L (4 por tipo de alimento) en una densidad de 10 org/tanque. La longitud patrón de los animales al inicio del experimento fue de 16.7 ± 0.68, 16.8 ± 1.14, 16.4 ± 1.19 cm para los animales alimentados con piensos para camarón, jurel y lubina, respectivamente. Los pesos iniciales de estos individuos fueron de 119.1 ± 18.56, 115.5 ± 21.29 y 87.4 + 21 g/animal, respectivamente. La TCE y la TCA fueron afectadas por el tipo de alimento, observándose los valores más altos de TCE para los animales alimentados con el alimento de lubina (1.02% g/día; 1.4:1, respectivamente) y los más bajos de TCE para los alimentados con alimento para camarón (0.45% g/día; 2.5:1, respectivamente). Un valor intermedio fue registrado en los animales alimentados con el alimento diseñado para jurel (0.5% g/día) con un valor alto de la TCA de 4.43:1. No se observó una relación entre las variables físico-químicas medidas y el tipo de alimento experimental, por lo que se pudo concluir que las condiciones experimentales fueron similares en todos los tratamientos. Así, los resultados obtenidos permiten recomendar el uso de alimento para lubina como una alternativa para la alimentación de Lutjanus guttatus bajo las condiciones de cultivo utilizadas en este estudio."

"Se realizaron los primeros experimentos de maduración, desove y cría larval de la corvina pinta, Cynoscion nebulosus en Sisal, México. Se obtuvo la maduración sexual y el desove espontáneo de reproductores capturados en el medio natural después de 20 meses en cautiverio. En un periodo de desove de 88 días, se obtuvieron 28 desoves, de los cuales 17 fueron viables. En total se colectaron 28 x 106 huevos, se observó 70% de viabilidad y 91% de fecundación. Los huevos desovados presentaron un diámetro promedio de 710 ± 8 μm con gota de aceite de 199 ± 9 μm. El porcentaje de eclosión de los huevos viables incubados fue 96% y la supervivencia larval a las 48 h después de la eclosión fue 79%. A las 48 h post-eclosión (PE), no se apreció restos de vitelo y solo vestigios de la gota de aceite. Se estimó que el periodo más adecuado para el suministro del primer alimento es entre 30 y 42 h PE, posterior a lo cual la supervivencia promedio disminuye abruptamente a 9,3 ± 4,4% y 11,3 ± 4,8% a las 54 h PE y 66 h PE, respectivamente. La cría larval se realizó en 2 tanques de 4 m3 a una densidad inicial de 75 huevos viables L-1 (95,6% de fecundación, 97,7% de eclosión y 88,8% de supervivencia a las 48 h) tuvo sobrevivencias de 0,4 y 1,2% a los 26 días. Se cosecharon 1011 y 2903 juveniles, con pesos húmedos de 0,13 ± 0,04 g y 0,16 ± 0,03 g y longitudes totales de 25,3 ± 2,6 mm y 27,4 ± 1,9 mm respectivamente. Las densidades y biomasas finales fueron de 0,25 y 0,50 juveniles L-1 y 0,03 y 0,08 kg m-3, respectivamente."

Induced spawning of common snook, Centropomus undecimalis (Bloch, 1792) and scale-up of larval rearing is described. Fertilized eggs were obtained from sGnRHa induced broodstock, acclimatized to captivity under natural conditions, for 5 years in 12-m 3 fiberglass tanks. Females with 402 ± 15 μm diameter vitellogenic oocytes were given an implant dose of 121 ± 31 μg kg − 1 while males received 83 ± 6 μg kg − 1 . A total of 4.33 × 10 6 eggs (18.5% floating) resulted from ten natural voluntary spawns. Two 5-m 3 cylindrical fiberglass tanks were stocked at an average of 40 floating eggs l − 1 , which resulted in 14 larvae l − 1 at 2 days post hatch (dph). A total of 70,936 juveniles were harvested on 45 dph (50.7% survival from first feeding). Two critical periods occurred, between 1 and 2 dph, and during transformation (20–23 dph). Final mean total length and weight at 46 dph were 21.26 ± 2.83 mm (0.42 mm day − 1 ) and 0.07 ± 0.03 g (0.002 g day − 1 ). Mean final density and biomass were 7.1 juveniles l − 1 and 0.479 kg m − 3 . The incidence of deformities was low, less than 2%, mostly lordosis. Improvements for spawning common snook including changes in feeding regime and GnRHa implant doses are detailed along with suggestions for further improvements in mass production technology.

On the Yucatan Peninsula there is an upwelling which allows access to a body of cold water that controls temperature in this area. This modulates the ecology and distribution of organisms that inhabit the continental shelf. The objective of this study was to determine the effect of different acclimation temperatures on the thermal biology of prey as mollusc, crustacean (Melongena corona bispinosa, Strombus pugilis, Callinectes similis, Libinia dubia) and predators as fish (Ocyurus chrysurus, Centropomus undecimalis) of Octopus maya. Octopus prey preferred temperatures between 23.5°C and 26.0°C, while predators preferred temperatures 26.4-28.5°C. The species with largest thermal windows were M. corona bispinosa (328.8°C(2)), C. similis (322.8°C(2)), L. dubia (319.2°C(2)), C. undecimalis (288.6°C(2)), O. chrysurus (237.5°C(2)), while the smallest thermal window was for S. pugilis (202.0°C(2)). The acclimation response ratios (ARR) estimated for prey ranged from 0.24-0.55 in animals exposed to CTMax and 0.21-0.65 in those exposed to CTMin. Amongst predators, ARR ranged from 0.30 to 0.60 and 0.41 to 0.53 for animals exposed to CTMax and CTMin, respectively. Correlating the optimal temperature limits of prey and predators with surface temperatures on the continental shelf and those 4m deep showed that the main prey, Callinectes similis and L. dubia, shared a thermal niche and that an increase in temperature could force these species to migrate to other sites to find optimal temperatures for their physiological functions. As a consequence the continental shelf community would undergo a structural change. Predators were found to be near their optimal temperatures in surface temperatures on the continental shelf. We conclude that they would remain in the area in a warming scenario. The size of the thermal window was related to the type of ecosystem inhabited by these species. These ARR intervals allowed us to categorize the species as temperate or tropical, according to the oceanographic conditions that prevail on the Yucatan Peninsula.

Yellowtail snapper (Ocyurus chrysurus) is one of the most important Lutjanids species in the Caribbean due to its great importance in recreational and commercial fishing activities. Studies related to digestive physiology are essential to improve survival after hatching as high mortalities have been reported during larviculture. The aim of this study was to determine the changes in the activities of alkaline and acid proteases, trypsin, chymotrypsin, leucine aminopeptidase, lipase, amylase and alkaline phosphatase in O. chrysurus during their initial ontogeny through biochemical techniques. Larvae were fed with live prey (Nannochloropsis sp and Brachionus rotundiformis) from the opening mouth until 10 days after hatching (DAH), subsequently fed with rotifers and Artemia sp. nauplii until 15 DAH and finally were feed with enriched lipid emulsion Artemia sp. metanauplii to 42 DAH. Activities of most alkaline digestive enzymes started 5 DAH expressing differentially according to larval growth and larvae live diet. Furthermore, the activity of pepsin in O. chrysurus peaked at 34 DAH, suggesting the presence of a functional stomach. It is concluded that the early activity of most alkaline enzymes reflects the contribution of pancreatic and cytosolic enzymes, and that the weaning period could start after 34 DAH after the observed peak of levels.

Common snook (Centropomus undecimalis) is one of the most important marine species under commercial exploitation in the Gulf of Mexico; for this reason, interest in developing its culture is a priority. However, larviculture remains as the main bottleneck for massive production. In this sense, our objective was to determine the changes of digestive enzymes activities using biochemical and electrophoretic techniques during 36 days of Common snook larviculture fed with live preys (microalgae, rotifers, and Artemia). During larviculture, all digestive enzymatic activities were detected with low values since yolk absorption, 2 days after hatching (dah) onwards. However, the maximum values for alkaline protease (6,500 U mg protein(-1)), trypsin (0.053 mU × 10(-3) mg protein(-1)), and Leucine aminopeptidase (1.4 × 10(-3) mU mg protein(-1)) were detected at 12 dah; for chymotrypsin at 25 dah (3.8 × 10(-3) mU mg protein(-1)), for carboxypeptidase A (280 mU mg protein(-1)) and lipase at 36 dah (480 U mg protein(-1)), for α-amylase at 7 dah (1.5 U mg protein(-1)), for acid phosphatases at 34 dah (5.5 U mg protein(-1)), and finally for alkaline phosphatase at 25 dah (70 U mg protein(-1)). The alkaline protease zymogram showed two active bands, the first (26.3 kDa) at 25 dah onwards, and the second (51.6 kDa) at 36 dah. The acid protease zymogram showed two bands (RF = 0.32 and 0.51, respectively) at 34 dah. The digestive enzymatic ontogeny of C. undecimalis is very similar to other strictly marine carnivorous fish, and we suggest that weaning process should be started at 34 dah.