Ciclo reproductivo de la almeja roñosa Chione undatella en las costas de la región minera de Santa Rosalía, BCS, México

Background: The organisms respond to changes in the environment, hence the reproductive process of an organism can be affected as a result of contamination. Chione undatella is a potential resource for fishing and cultivation, which has been intensively exploited for many years on the Mexican Pacific coast. Goals: The main objective of this study was to characterize the reproductive cycle and spawning temporality, estimate the size at first maturity, and determine if there is tissue damage that may have adverse effects on reproduc­tion of C. undatella because of the contamination found in the mining port of Santa Rosalía, Gulf of California. Methods: Through histological analysis, the general condition index (GCI), and environmental parameters, we evaluated aspects of the reproductive biology and health of the frilled venus clam from the coastal area of the port of Santa Rosalía. Results: C. undatella has reproductive activity throughout the year, unrelated to the concentration of chlorophyll-a, or to temperature. An inverse correlation was found between the GCI and the phase of development with higher frequency in females. The size at first maturity is 57 mm LC. In the gonadal tissue (> 80% of the individuals) an infiltration of eosinophilic cells was observed in all phases of gonadal development with an intermediate to abundant intensity (> 60% of the organisms). Conclusions: Although C. undatella has reproductive activity throughout the year, the high prevalence of hemocytic infil­tration in the gonadal tissue suggests a potential deficiency in its reproduction. We recommend more studies be undertaken to confirm this preliminary finding and determine the relationship of the deficiency with the contamination present in the area.Antecedentes. El proceso reproductivo además de responder a cambios en el medio ambiente, puede verse afectado como consecuencia de un medio marino contaminado. Chione undatella es un recurso potencial, pesquero y de cultivo que se ha explotado intensivamente por muchos años en la costa del Pacífico mexicano.  Objetivos. El principal objetivo de este trabajo fue caracterizar el ciclo reproductivo y temporalidad del desove, estimar la talla de primera madurez y determinar si existen daños tisulares que puedan tener efectos adversos en la reproducción de C. undatella como resultado de la contaminación presente en el puerto minero de Santa Rosalía, Golfo de California. Métodos. A través del análisis histológico, del índice de condición (ICG) y de parámetros ambientales, se evaluaron aspectos de la biología reproductiva y salud de la almeja roñosa en la zona costera del puerto de Santa Rosalía. Resultados. C. undatella presenta actividad reproductiva durante todo el año sin relación con la concentración de clorofila a, ni con la temperatura.  Se encontró una correlación inversa entre el ICG y la fase de desarrollo de mayor frecuencia (madurez) en hembras. La talla de primera madurez es 57 mm LC. En el tejido gonadal (>80% de los individuos) se observó una infiltración de células eosinófilas en todas las fases de desarrollo gonádico con una intensidad de intermedia a abundante (>60% de los organismos). Conclusiones. A pesar de que C. undatella presenta actividad reproductiva todo el año, la gran prevalencia de infiltraciones hemocíticas en el tejido gonadal sugiere una potencial deficiencia en su reproducción. Es importante hacer más estudios para confirmarlo y para determinar su relación con la contaminación presente en la zona

Reproductive cycle of the Cortez angelfish Pomacanthus zonipectus (Gill, 1863) (Pomacanthidae) from the Gulf of California, Mexico.

Different aspects of the reproductive biology of the Cortez angelfish Pomacanthus zonipectus were studied between July 1992, and June 1993 at Espíritu Santo Island, Baja California Sur, Mexico. The ovarian and testes development was analyzed using histological techniques. The reproductive cycle was determined and quantitatively analyzed. Five stages of gonadal development were established: resting, developing, ripe, spawning, and spent. P. zonipectus is a partial spawner that reproduces from June to November. The reproductive cycle of P. zonipectus shows a clear seasonally related with the water temperature, and gonadosomatic index. Gametogenesis started when water temperatures began to increase and continued during warmer months (26°C to 30°C). The interval of size at first sexual maturity was 210-220 mm total length

Notes on the growth, survival, and reproduction of the lions paw scallop Nodipecten subnodosus maintained in a suspended culture

The study was conducted from March 1999 to November 2002 in a suspended culture located in Bahía Juncalito, Gulf of California, Mexico. Nodipecten subnodosus (Sowerby, 1835) is a species with fast growth (ø=3.91) and alometric, with a seasonality of 0.78 and an amplitude of 0.8. Its growth was described by the von Bertalanffy model. An average growth rate of 4 mm/month was estimated for the first 16 months of the study. Then, it decreased to 1.3 mm/month until the end of the experiment. The survival was high (? 89 %) and did not change substantially until November 2001 when it decrease to 40%. In Bahía Juncalito, N. subnodosus attain its first spawn at nearly 2-years old with a mean shell height of 72 mm

Evidence of health impairment of Megapitaria squalida (Bivalvia: Veneridae) near the hot spot of a mining port, Gulf of California

It is known that organisms inhabiting polluted marine habitats may experience adverse physiological effects. The port of Santa Rosalía, Gulf of California, is characterized by high concentrations of heavy metals in sediments, particularly Cu, Zn, Co, Mn, Pb, and U, which are potentially toxic to the marine biota. In addition, this port receives urban wastewater that contributes mostly organic pollutants to the coastal zone. Goals. The main objective of this work was to determine whether clams in the mining region showed adverse effects because of the contamination. Methods. Through the analysis of biometric parameters, condition index, and weight-length relationship, the overall health of the chocolate clam Megapitaria squalida was evaluated in the coastal zone of the Santa Rosalía port and compared with data for clams from four mining-free areas. Results. Our findings revealed that clams from Santa Rosalía showed poor health, evidenced by their smaller size, inferior condition, and negative allometric growth compared to clams from all other sites, including San Lucas, a site located a few kilometers away from the pollution hot-spot and where the conditions of temperature and food availability are similar to those in the port area. Conclusions. All of the above suggests negative physiological effects in this species possibly caused by contamination from metals and/or organic pollutants from urban discharges. Particularly, it is likely that M. squalida at the mining site allocates more energy towards depurating or storing metals, in turn leading to poorer condition and deficient growth

Estimation of growth parameters in a wild population of lion-paw scallop (Nodipecten subnodosus ) in Bahia de Los Angeles, Baja California, Mexico

The lion-paw scallop Nodipecten subnodosus is a commercially important resource in the northwest of Mexico; however few studies evaluate its growth. Length of shell was used to estimate individual growth parameters of the lion-paw scallop from a wild population. Monthly samplings were performed from January to December 2006 in Bahia de Los Angeles on the western coast of the Gulf of California, Mexico. Morphometric relationships between total length, height, total weight, and mass weight were estimated. The number of cohorts was determined monthly using the multinomial technique based on a likelihood function. The cohort that was best represented over time was used to fit the stationary growth model of von Bertalanffy. The results indicated that this species presents negative allometric growth and showed high correlation among different morphometric measures (R2 > 0.88). Length frequency distributions showed two cohorts in each sample, except from August to November when there were up to three cohorts, with greater variance in those of intermediate sizes. The growth parameters were: L? = 19.06 cm, k = 0.47 year-1, t0 = -0.19 years, C = 0.38, ts = 0.37. Due to fluctuations in the growth of the species, assessments should be performed based on age-structured models to support fishery management measures for this species

La pesquería de la almeja chocolata Megapitaria squalida (Bivalvia: Veneridae) en Baja California Sur, México

The Squalid Callista Megapitaria squalida is one of the most important bivalve fisheries in Baja California Sur. However, there is scarce information about the current state of the fishery. In order to obtain an overview of the fishery development, spatial and temporal catch trends were analyzed. The analysis was based on monthly and by area catches records from 1999 to 2006. Results show six major fishing areas: La Paz Bay, Ojo de Liebre Lagoon, Magdalena Bay, San Ignacio Lagoon, Loreto and Santa Rosalía. In the first three areas it was observed 96% of the total catch. There was a general increase in catches from 1992 (315 t) to 2002 (1,128 t) due to the catch increase in Ojo de Liebre Lagoon and La Paz Bay. However, a substantial catch decline occurred in Magdalena Bay from 2001 (457 t) to 2006 (73 t). Since 2002 there has been a general catch decline. Therefore, the conclusion of the study affirms that the fisheries in La Paz Bay and Ojo de Liebre Lagoon are at their maximum level of exploitation. In Magdalena Bay there is evidence of overfishing, while San Ignacio Lagoon, Loreto and Santa Rosalía could have developing potential. A detailed stock assessment is recommended due to the recent negative catch trends that could indicate an excessive fishing pressure.La almeja chocolata Megapitaria squalida representa una de las pesquerías de bivalvos más importantes en Baja California Sur. Sin embargo, poco se sabe sobre el estado actual de esta pesquería. Con el objetivo de obtener una perspectiva del desarrollo de la pesquería, se analizaron las tendencias espacio-temporales de las capturas, utilizando los registros de producción mensual y por localidad de 1999 a 2006. Los resultados muestran seis regiones de pesca importantes: Bahía de La Paz, Laguna Ojo de Liebre, Bahía Magdalena, Laguna San Ignacio, Bahía de Loreto y la costa de Santa Rosalía. En las tres primeras se obtuvieron 96% de las capturas totales. Se observó un incremento en la producción de 1992 (315 t) a 2002 (1,128 t) debido al aumento en la Laguna Ojo de Liebre y Bahía de La Paz, sin embargo es notable la disminución de las capturas en Bahía Magdalena desde el 2001 (457 t) al 2006 (73 t). A partir de 2002 se observó una disminución general de las capturas. Se concluye que la pesquería en Bahía de La Paz y Laguna Ojo de Liebre se encuentra en su máxima capacidad, en Bahía Magdalena hay indicios de sobreexplotación, mientras que en Laguna San Ignacio, Bahía de Loreto y Santa Rosalía podría haber potencial de desarrollo. Se recomienda profundizar en la evaluación del recurso, debido a que las tendencias de disminución de las capturas observadas en los últimos años, pueden estar indicando una excesiva presión de pesca

Biología reproductiva del pez vela Istiophorus platypterus en la Bahía de Acapulco, México: Reproductive biology of sailfish

Background. The sailfish Istiophorus platypterus is a viviparous billfish species, it is caught by trolling in the sports fishery in Mexico. However, to date, there has been no reproductive biology studies of sailfish in Acapulco Bay, although the reproductive aspects of any species represent essential information for the design of management plans. Goals. Estimate the spawning frequency and batch fecundity to quantify reproductive characteristics of sailfish in waters off Acapulco, Bay. Methods. During the period 2008–2019, a total of 581 fish were sampled. Macroscopy analysis and quantitative histology was used to describe reproductive characteristics of the sailfish gonads. Results. 55.8% of the organisms analyzed were males, the remaining 44.2% were females, the sex ratio (1.26 M: 1 H) was different from the expected theoretical ratio (X2 = 7.53). The ovaries of 155 females were classified into five ovarian development phases based on histological analysis of the most advanced group of oocytes. Sailfish are multiple spawners with asynchronous oocyte development. Batch fecundity for 14 females with the presence of hydrated oocytes but without postovulatory follicles ranged 0.330 to 2.092 × 106 eggs with an average of 1.07 × 106 eggs. Gonadosomatic indices (GSI) indicated that sailfish have a reproductive period with peaks in August and October (mean monthly GSI= 4.3% and 5.4%). Conclusions. Population sailfish in Acapulco Bay is composed of males and females in similar proportions, with a gonadal development by groups that can be described in five development phases, a reproductive maximum during the warm months of the year and a relatively high fecundity.Antecedentes. El pez vela Istiophorus platypterus (Shaw, 1792) es una especie vivípara (Isthiophoridae) objeto de la flota deportiva de pesca en México. Aún y cuando los aspectos reproductivos de cualquier especie representan información esencial para el diseño de planes de manejo, a la fecha no se ha realizado un examen macroscópico e histológico de las características reproductivas del pez vela en la Bahía de Acapulco, Guerrero, México. Objetivo. Estimar la frecuencia de desove y la fecundidad, con la finalidad de cuantificar las características reproductivas del pez vela en aguas de la Bahía de Acapulco. Métodos. Durante el período 2008-2009, se muestrearon un total de 581 peces. Se utilizó análisis macroscópico e histología cuantitativa para describir las características reproductivas de las gónadas del pez vela. Resultados. El 55.8 % de los organismos analizados fueron machos, el 44.2 % restante fueron hembras, la proporción de sexos (1.26 M:1H) fue diferente de la proporción teórica esperada (X2 = 7.53). El análisis histológico de las gónadas de las hembras permitió identificar cinco fases de desarrollo ovárico. El desarrollo gonádico fue sincrónico por grupos, por tanto, la especie puede ser calificada como un desovador parcial múltiple. La fecundidad estimada varió entre los 0.330-2.092 × 106 ovocitos, con un promedio de 1.07 × 106 ovocitos. El índice gonadosomático (IGS) indicó que el pez vela tiene un período de reproducción con picos en agosto y octubre (IGS mensual promedio = 4.3 % y 5.4 %, respectivamente). Conclusiones. La población de pez vela en la Bahía de Acapulco está compuesta de machos y hembras en proporciones similares, con un desarrollo gonádico por grupos que puede ser descrito en cinco fases de desarrollo, un máximo reproductivo durante los meses cálidos del año y una fecundidad relativamente alta

Biología reproductiva del "conejo" Caulolatilus affinis, Gill 1865 (Pisces: branchiostegidae,) en el Canal Cerralvo, B.C.S., México.

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