The shell height-body weight relationship of the black clam Chionista fluctifraga cultivated in the intertidal of the southeastern Gulf of California, was evaluated for the first time, to improve the knowledge in determining its harvesting time. Clam seeds (n=900,000; 6.1±1.9 mm) were produced in the laboratory. The culture was divided into pre-fattening in racks on the bottom (2 months) and fattening directly in the bottom (16 months) from May 2018 to October 2019. Each month, 60 (n=1080) clams were randomly selected to stablish the morphometric relationship between shell height (SH) and body weight (BW). The growth rate (mm/d and g/d) was recorded. The SH-BW Interaction in both cultivation phases showed positive allometry. SH in prefattening and fattening registered a growth rate of 0.072 and 0.058 mm/d, respectively. In fattening, the interaction BW-SH displayed a high coefficient of determination (R2=0.99). A final survival rate of 90% was obtained. The results yielded the equations that describe the relative growth of C. fluctifraga for the fattening stage. A harvesting time after 10 months of fattening in the intertidal zone is stablished to reach the commercial size (35 mm, SH).

Objetivo. Determinar la presencia de Perkinsus sp. en la almeja Chionista fluctifraga cultivada en una zona intermareal del sureste del Golfo de California, utilizando la tinción del medio fluido de tioglicolato de Ray (MFTR) y la reacción en cadena de la polimerasa (PCR). Material y métodos. La prevalencia y carga parasitaria de Perkinsus sp. se obtuvieron y se correlacionaron mensualmente con las condiciones ambientales del agua y los indicadores biométricos de la almeja (n=540), de mayo de 2018 a septiembre de 2019. Resultados. Se detectaron presuntas hipnosporas del protozoo en ocho meses de cultivo. La prevalencia fluctuó de 3.3% a 13.3%; la carga parasitaria osciló entre 2 y 1286 hipnosporas/g de tejido. La intensidad de la infección varió de negativa a leve. La prevalencia y la carga parasitaria se correlacionaron positivamente entre sí (r=0.61, P˂0.05), pero no con los parámetros ambientales, ni con los indicadores biométricos de la almeja. La prueba de PCR fue negativa para los casos positivos de MFTR. Conclusiones. Se detectaron presuntas hipnosporas de Perkinsus sp en C. fluctifraga sin claros indicios de infección que comprometieran la salud de la almeja en cultivo. Se recomienda el monitoreo constante de Perkinsus sp. en C. fluctifraga , para establecer posibles infecciones.

Although muricid snails are an important ecological and fisheries resource in northwest Mexico, information on their allometry and morphometry is scarce. For one year (February 2022-January 2023), 30 specimens of the “Chinese black” snail, Hexaplex nigritus (shell height = 101.4 ± 13.7 mm, total snail weight = 192.3 ± 89.1 g) were monthly collected from a coastal lagoon of the southeastern Gulf of California. The biometrics of shells (height SH, length SL, width SW, and shell opening width WSO) and operculum (height OH, length OL, and width OW) and weight variables (total snail weight TWS, total hell weight TSW, total tissue weight TTW, total gonad weight TGW, and total operculum weight TOW) of sampled snails were morphometrically analyzed. All biometric indicators of the snail shell and operculum showed significant differences (P < 0.05) monthly and presented linear and positive equations in all associations. The SH/SL relationship represents the most appropriate tool to describe the relative growth of this gastropod (coefficient of determination, R2 = 0.80), considering an empty shell; meanwhile, TWS/SL better describes the shell/weight interaction (R2 = 0.80) for live snails. The water temperature showed a positive correlation with the biometric indicators. The measurements obtained from the shell dimensions of this gastropod indicate that the sampled population consisted of adult snails. These data are fundamental for the management and conservation of this muricid species in the study area, providing valuable information for planning sustainable management strategies.

The artisanal harvesting of Anadara mazatlanica is of fundamental importance to the sociocultural identity and economic livelihood of the coastal communities located in the San Ignacio–Navachiste–Macapule (SINM) lagoon system in Mexico; its conservation depends on the sustainable use of the species and its habitat, which is considered vulnerable to multiple socioeconomic and environmental pressures. The circular economy (CE) emerges as a potential approach to integrate resource exploitation, waste reduction, and community-oriented conservation management. This study analyzed the perceptions of A. mazatlanica harvesters, covering social, economic, environmental, and recycling dimensions (theoretical approach) and corroborated by exploratory factor analysis, thereby identifying the main challenges and areas of opportunity for the transition to sustainable development models. A quantitative (exploratory–descriptive) approach was used, employing a structured questionnaire that included a sociodemographic section and 23 items on a Likert scale. The findings revealed a high sociocultural appreciation of artisanal fishing and community cohesion ($\overline{\mathrm{x}}$ = 4.55). In contrast, economic perceptions showed a moderately negative level ($\overline{\mathrm{x}}$ = 2.48), indicating a dependence on intermediaries, limited added value, and institutional support. The CE dimension ($\overline{\mathrm{x}}$ = 1.55) suggested an underutilization of shells. In addition, the mean value of 3.44 for environmental perceptions highlighted awareness of ecosystem deterioration and regulatory deficiencies. These results highlight the need to enhance fisheries governance, diversify value chains, and integrate circular innovations to ensure the sustainability of this fishery.

RESUMEN | Se detectaron presuntas hipnosporas de Perkinsus sp. en una población silvestre de la almeja Megapitaria squalida (enero-diciembre 2013) al norte del estado de Sinaloa, México, con la técnica de tinción de tioglicolato (MFTR). Se colectaron 30 almejas cada mes (64.08 ± 4.75 mm altura de la concha y 68.76 ± 14.34 g de peso). Se obtuvieron los parámetros fisicoquímicos del agua (temperatura, salinidad, pH, oxígeno disuelto, profundidad y transparencia). La prueba MFTR detectó células esféricas de color obscuro, indicando la presencia de presuntas hipnosporas de Perkinsus sp. todos los meses de muestreo menos en diciembre. La intensidad de la infección promedio fluctuó de negativa a ligera, mientras que la prevalencia máxima fue de 70% observada en mayo. La carga parasitaria mostró correlación con los indicadores métricos de la almeja. No se obtuvo correlación (p > 0.05) entre la prevalencia del patógeno con todos los parámetros estudiados. Los resultados sugieren que M. squalida es poco susceptible a la infección de Perkinsus sp. ABSTRACT | Presumptive Perkinsus sp. hypnospores were detected in a wild population of the callista clam Megapitaria squalida (January-December 2013) from the north of the state of Sinaloa, Mexico, using the thioglicollate staining technique (MFTR). 30 clams were collected each month (64.08 ± 4.75 mm shell height and 68.76 ± 14.34 g weight). The physicochemical parameters of the water (temperature, salinity, pH, dissolved oxygen, depth, and transparency) were obtained. The MFTR test detected spherical cells of dark color every sampling month, except in December, indicating the presence of presumptive Perkinsus sp. hypnospores. The intensity of infection fluctuated from negative to light, while the maximum prevalence was 70% observed in May. The parasitic load showed correlation with the metric indicators of the clam. No correlation (p > 0.05) was obtained between the prevalence of the pathogen with all the parameters studied. The results suggest that M. squalida is little susceptible to the infection of Perkinsus sp.