Aspectos particulares de la maduración gonádica y talla de primera madurez de Atrina maura (Bivalvia: Pinnidae)

The gonadal maturation of Atrina maura was examined by means of histological analysis and quantitative criteria. Particular features not previously described for this species are reported in this study: in both males and females the undifferentiated stage is absent and there is massive gamete resorption when the seawater temperature reaches 25°C; in males, there is continuous spawning concurrent with other gonadal development stages and the adipogranular cells surrounding the acini walls decrease with testis ripeness, which suggests they play an energetic role. Atresia displayed two stages: cytoplasmic structures with oocyte degeneration and digestion by hemocytes. The oocyte diameter was larger than that reported for cultured specimens. Size at first maturity was reached at 23.3 cm in shell height (SH) (12.2 cm in shell length, SL) in females and 22.8 cm SH (12.0 cm SL) in males.Se analizó histológicamente y usando criterios cuantitativos el proceso de maduración gonádica de Atrina maura. Se reportan características particulares que no han sido descritas previamente para la especie: ausencia de la fase de indiferenciación y reabsorción masiva de gametos, tanto en hembras como en machos, cuando la temperatura del agua alcanza los 25°C; en los machos presencia de eyaculación continua simultánea con otras fases de desarrollo gonádico y células adipogranulares arregladas alrededor de las paredes de los acinos que disminuyen conforme avanza la maduración, sugiriendo un papel energético. La atresia presentó dos fases: estructuras citoplasmáticas con degeneración ovocitaria y digestión por hemocitos. El diámetro de los ovocitos fue mayor que los reportados para organismos de cultivo. La talla de primera madurez para las hembras se estableció en 23.3 cm de altura de la concha (AC) (12.2 cm de longitud de la concha, LC) y para los machos en 22.8 cm de AC (12.0 cm de LC)

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

Length-weight relationships and relative condition factor in razor surgeonfish, Prionurus laticlavius (Teleostei: Acanthuridae) from the southwestern coast of the Gulf of California, Mexico: Relación peso-longitud y factor de condición relativo del navajón barbero Prionurus laticlavius (Teleostei: Acanthuridae) de la costa sudoccidental del Golfo de California, México

The razor surgeonfish, Prionurus laticlavius, listed on the IUCN Red List of Threatened Species under the Least Concern category, plays an important ecological role as energy regulator in reef communities, but it is sought by the aquarium and aquaculture industry, and also is consumed by people. This study estimated the length-weight relationship (LWR) and relative condition factor (Krel) in P. laticlavius. The equation for length-weight relationship was TW= 0.02 TL3.01 for the Overall category, and the relative condition factor was 1.28. A total of 379 fish (3-45.6 cm total length) were collected in the southwestern coast of the Gulf of California using harpoon (for large fishes) and hand net (for small fishes), of which 181 were females (20.2-45.6 cm), 137 males (20.6-43.4 cm), and 61 juveniles (3-19.5 cm). Allometric coefficient b of LWR for the Overall category suggested isometric growth (b = 3.01), positive allometric growth for juveniles (b = 3.14), and negative allometric growth for adults (2.75). Results of Krel showed higher values for females during the warm season. The population showed a good nutritional condition, mainly in the warm season. This work is the first to estimate LWR and Krel for P. laticlavius, which will inform stock assessment and the management of this species in the Gulf of California

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

Características ecofisiológicas de la reproducción de Nodipecten subnodosus (Sowerby, 1835) (Pectinidae) en la Laguna Ojo de Liebre, B.C.S.

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