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Abstract A total of 381 specimens of the tilapia Oreochromis mossambicus collected monthly from May 2017 to May 2018 in the Laguna de Los Patos, Cumaná, Venezuela, to evaluate reproductive parameters of this non-native species. Significant differences were found in relation to average height and weight between males and females, with the highest values in males. The sex ratio was 1:1.5 (males:females), which deviates significantly from the expected 1:1 ratio. The mean length of sexual maturity (Lm50) was 18.0 cm in females and 20.1 cm in males, reflecting that females mature at smaller sizes than males. The monthly variations of the gonadosomatic index (GSI) and the stages of sexual maturity show two reproductive peaks during the study, in October 2017 and April 2018, coinciding with the rainy and dry seasons in the region respectively. The condition factor (CF) showed significant differences between months, but not between sexes, with an average of 1.87 in females and 1.84 in males. The average absolute fecundity was 921 ± 604.6 eggs per fish, with a relative fecundity of 8.36 ± 3.09 eggs per gram of fish. Differences in oocyte size in mature females confirm that the species can spawn repeatedly over a period, which is considered an important factor for the establishment of tilapia in non-native environments.

The optimal tide height at which the intertidal oyster bed system (IOBS) should be installed to cultivate Crassostrea corteziensis in Boca de Camichín (BC), Nayarit, Mexico, during the intermediate grow-out stage (39.3–60.2 mm in shell length) was determined. Temperature, salinity, chlorophyll a (Chla), and turbidity were recorded 3 times a day. A trophic state index (TSI) was calculated with Chla and turbidity data. Three treatments corresponding to tide levels were tested: (1) high level (14 cm above mean sea level [MSL], emersion time [ET] = 56.4% of the total duration of the experiment), (2) intermediate level (MSL, ET = 48.6%), and (3) low level (41 cm below MSL, ET = 32.1%). Gross growth rates and absolute and relative monthly growth rates were calculated to identify periods with highest growth relative to environmental conditions. Finally, the effect of the treatments on the dimensions and weight of the oysters was studied. The results indicate that BC water was mesotrophic in April–June and eutrophic in July–August. The low tide level was the best for IOBS operation, with growth rates of 0.15, 0.10, and 0.07 mm·d–1 in shell length, width, and thickness, respectively, and 0.204 g·d–1 wet weight. Cumulative mortality was lower in the low (18.5%) and intermediate (16.4%) treatments. Shell thickness was significant reduced (P < 0.05) in the high treatment and total wet weight was reduced in the high and intermediate treatments. The results of this study offer a viable and different alternative to the cultivation of C. corteziensis in strings that is currently carried out in Boca de Camichín, Nayarit, Mexico.

Se realizó un análisis de la producción de crías de tilapia Oreochromis niloticus en instalaciones acuícolas en México de 2014 a 2021, a partir de la producción pesquera y acuícola registrada a nivel nacional. Para ello se analizaron los registros de producción de crías de tilapia en laboratorios, los volúmenes de cosechas anuales registrados en las instalaciones acuícolas que operan en las diferentes entidades federativas y las capturas de tilapia registradas de 2009 a 2018. En 2018 se produjeron en México 168.359 t de tilapia y se importaron 127.981 t, con un consumo nacional aparente de tilapia registrado de 298.644 t. Ese año se produjeron 169,2 millones de crías de tilapia (Conapesca 2018). Para cubrir el déficit de tilapia por la importación de 127.981 t, se requiere teóricamente una producción adicional estimada en 511,9 y 383,9 millones de crías de tilapia, considerando los escenarios de siembra de 4 y 3 organismos para cosechar un kilogramo (2 organismos de 500 g de peso promedio), con supervivencias durante su cultivo del 50 y 66,6 % y producciones de 7,5 - 10 t por ha, respectivamente. Se analizaron los sistemas de producción de tilapia a nivel extensivo y semi-intensivo por su sustentabilidad y se emiten conclusiones técnicas para mejorar el aprovechamiento de este recurso biológico-pesquero, que impacta favorablemente en la socioeconomía de las diferentes regiones donde se cultiva.

Para facilitar la toma de decisiones en cultivos de organismos fotoautótrofos, se proponen distintos índices que permiten evaluar, de modo efectivo la productividad de los sistemas al emplear diferentes tipos de luz. El coste lumínico por célula producida, se obtiene mediante el indicador Consumo Lumínico Celular (CLC). El rendimiento de cada fuente luminosa, con la Densidad Máxima por Potencia Instalada (DMPI). El Factor de Comparación de Producción (FCP) calcula las células obtenidas con cada tipo de iluminación, teniendo en cuenta la potencia instalada y el tiempo requerido de cultivo. El Factor de Elección de Luz (FEL) expresa el coste celular por W empleado, teniendo en cuenta la productividad celular obtenida, así como la vida útil y el precio de adquisición de cada lámpara. Se ensayaron 3 modelos de luminarias comerciales, (2 LED, y una fluorescente) en el cultivo de 4 especies de microalgas (Tetraselmis suecica, Isochrysis galbana, Diacronema lutheri, y Skeletonema costatum), utilizadas con frecuencia en criaderos de moluscos bivalvos. Los resultados mostraron que con recuentos celulares y aplicando los índices presentados en esta publicación se puede llegar a determinar la eficiencia del tipo de luz empleada en instalaciones industriales donde se realice la producción de fitoplancton con iluminación artificial.

Objective: To characterize the tilapia (Oreochromis niloticus) production system in Zacatecas, Mexico. Methodology: Seventeen Aquaculture Production Units (APU) in Zacatecas were analyzed, using a crosssectional design and qualitative-quantitative method. The instrument used was a questionnaire, and the sampling was non-probabilistic. Results: Tilapia cultivation is conducted in various types of ponds, with an average of 2340 organisms per pond, yielding a production of 5705.88 kg year-1, and a sale price of $116.47 pesos kg-1 of fresh gutted fish at the farm gate. Production costs are primarily associated with concentrated feed and electrical energy. Regarding the financial characteristics analyzed, APUs are categorized into four types of production: basic, as a complementary activity with limited economic resources; pre-intermediate, characterized by basic infrastructure and managed by adult aquaculturists (49-55 years old); Intermediate, full-time dedication with average profitability; and high-intermediate, with optimal infrastructure and activity managed by adult aquaculturists aged 30-55 years with a propensity to adopt technological innovation in aquaculture. Limitations/Study Implications: No major limitations were identified. Conclusions: In general, aquaculturists perceive stagnation in their activity due to lack of promotion, production scheduling, and insecurity. It is necessary to develop an inter-institutional strategy where universities, research institutions, and government agencies participate to promote elements of policy, financing, and training. [ABSTRACT FROM AUTHOR]

We had previously revised the systematics of four species of Macrobrachium Spence Bate, 1868 from the Pacific coast of Mexico, including the Baja California Peninsula (BCP): M. americanum Spence Bate, 1868 , M. digueti (Bouvier, 1895), M. hobbsi Nates & Villalobos in Villalobos Hiriart & Nates Rodríguez, 1990 , and M. occidentale Holthuis, 1950. Genetic analyses of the mitochondrial markers 16S ribosomal RNA (16S) and cytochrome oxidase I (COI) of individuals of these morphological species from BCP have shown that, even facing the Gulf of California (Sea of Cortés) as an apparent marine ecological barrier, they are conspecific to their respective genetic lineages (species) found from the Pacific slope of mainland Mexico. We discuss the systematics of the fifth species of Macrobrachium from the Mexican Pacific slope, M. tenellum (Smith, 1871) to test the hypothesis that individuals of the putative M. tenellum from BCP belong to the same species from the Pacific slope of mainland Mexico. We revised the morphological characters of taxonomic importance using material obtained in the field and voucher material deposited in Mexican scientific collections, and performed molecular genetic analyses with newly generated fragments of the mitochondrial markers 16S and COI. We conclude, as in our previous studies on Macrobrachium species of the region, that the examined specimens of the putative M. tenellum from BCP belong to the same species found on the Pacific slope of mainland Mexico, and that oceanic dispersal is responsible for the distribution of the species of Macrobrachium in the peninsula rather than by vicariant events. [ABSTRACT FROM AUTHOR]

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The search for exotic pathogens related to the outbreaks and in surveillance samplings of the Mexican oyster farms, is a recent activity achieved by academic institutions and state committees for Aquatic Animal Health, with remarkable results. In samples of Crassostrea gigas collected through December 2009, January 2010 and November 2010, and of C. corteziensis in September 2011, the protozoan Marteilia refringens was detected for the first time in the Gulf of California. The carrier oysters were from cultures without abnormal mortality rates, whereby, the use of histology, in situ hybridization and transmission electron microscopy studies are necessary to determine if M. refringens has become established in the Gulf of California oyster cultures. Detection of M. refringens is of great concern to the global oyster farming industry.

El trabajo describe por primera vez el desarrollo larvario hasta juvenil de Euvola vogdesi y las experiencias en el cultivo larvario de esta especie. Los reproductores en acondicionamiento gonádico alcanzaron la madurez total a los 42 ± 5 días. La inducción al desove se realizó con los métodos de shock térmico (18-20°C/20 min) e inyección intragonadal de serotonina (0,3 mL a 0,25 mM). En experimentos del efecto de las temperaturas 20, 23 y 25°C en el crecimiento larvario, se obtuvo a 25°C el mayor crecimiento. A esta temperatura, los cultivos larvarios con cambios en la densidad y dieta entre 1992 y 2001 mostraron diferencias significativas en el crecimiento, logrando disminuir el tiempo de cultivo larvario de 25 días a 11 días. En la etapa de pre-engorda, los juveniles de 3,5-4,0 mm de longitud de concha, tuvieron una supervivencia de 3-5%, a los 55 ± 5 días. Los juveniles de 6-7 mm de longitud presentaron las valvas características de los adultos, después de 25-30 días.

The effect of refrigerated 48h transport and 4 days storage on the quality and shelf life of the whole lion's paw scallop Nodipecten subnodosus gonad was evaluated. Proximal composition, adenosine 5´triphosphate (ATP) and related products, K-value, total volatile bases (TVB-N), trimethylamine (TMA-N), pH, fatty acid profile and microbiological analyses were quantified. Gonad holds a significant composition of essential fatty acids while levels of gonadal ATP were initially low; moreover, K-value of the gonad remained constant. With respect to TVB-N and TMA-N, only the former exceeded allowed limits. The pH level showed no significant variation during storage and, despite the high level of TVB-N, according to the TMA-N as well as microbiological analyses it was demonstrated innocuity after 4 days under the transportation and storage conditions utilized.

A new species of the freshwater cyclopoid copepod genus Metacyclops Kiefer, 1927 is described from a single pond in northern Mexico, within the binational area known as the Chihuahuan Desert. This species belongs to a group of Metacyclops species with a 3443 spine formula of swimming legs. It is morphologically similar to Metacyclops lusitanus Lindberg, 1961 but differs from this and other congeners bya unique combination of characters, including a caudal rami length/width proportion of 3.5–3.8, a innermost terminal seta slightly longer than the outermost terminal seta, intercoxal sclerites of legs 1-4 naked, a strong apical spine of the second endopodal segment of leg 1 and one row of 6-8 small spinules at the insertion of this spine. The finding of this species represents also the first record of the genus in Mexico and the third in North America, where only two other species, M. gracilis (Lilljeborg, 1853) and M. cushae Reid, 1991 have been hitherto reported. This is also the first continental record of a species of Metacyclops from an arid environment in the Americas. This species appears to be endemic to the Chihuahuan Desert, thus emphasizing the high endemicity of this area.