The structure and functioning of the food web of the Francisco Coloane Marine Area in the Magellan Strait, Chile, was quantified, with an emphasis on identifying the ecological role of the squat lobster (Munida gregaria) and the Fuegian sprat (Sprattus fuegensis). Food web indicators, the trophic level, and centrality indices were estimated using Ecopath with Ecosim. Dynamic simulations were carried out to evaluate the ecosystem impacts of biomass changes in squat lobster and Fuegian sprat. The model calculated a total ecosystem biomass of 71.7 t km⁻² and a total primary production of 2450.9 t km⁻² year⁻¹. Squat lobster and Fuegian sprat were located in specific trophic levels of 2.3 and 2.7, respectively. Squat lobster reduction produced a decrease in the biomass of red cod (42–56%) and humpback whales (25–28%) and Fuegian sprat reduction a decrease in penguins (15–37%) and seabirds (11–34%). The Francisco Coloane Area is an immature ecosystem with productivity and energy flows values within those reported for productive ecosystems; the role of the squat lobster seems to be related to the structure of the food web, and the role of the Fuegian sprat seems to be related to the functioning of the ecosystem and to the energy transfer to top predators.

Studies have shown that environmental variables significantly affect variation in stock abundance of marine populations. The northern Gulf of California (NGC) is a highly productive region of interest due to its fish resources and diversity. Conservation of the marine species inhabiting the region is of public interest. Our study analysed the influence of physical environmental factors on several commercial marine species, using catch per unit effort (CPUE) as a proxy for abundance. Generalized additive models were used to test the significance of selected environmental variables on stock abundance. Deseasonalized cross-correlation analysis was used to examine time-lagged correlations between CPUE and abiotic variables to identify response timings. The results suggest that for most commercial species the sea surface temperature and the long-term climate Pacific Decadal Oscillation index are the predominant predictors for species abundance, followed by the Colorado River discharge. The Multivariate ENSO Index and the Pacific-North American pattern indices also showed specific effects on certain species. The NGC is a highly dynamic region, where species respond to environmental changes according to the characteristics of their life histories.

The spotted rose snapper (Lutjanus guttatus) is a commercially important species that provides economic income to small-scale fisheries in the Pacific coastal regions of Guatemala; however, there are no studies on this species that establish a baseline of knowledge on their reproductive aspects and potential management measures. The present study was carried out to obtain the first knowledge on the reproductive behavior of this resource, which will contribute to the establishment of future management strategies for the fisheries. Aspects of gonadal-maturity phases and reproductive indicators such as the condition factor, gonadosomatic index, and temporal oocyte diameter were analyzed to estimate reproductive development and the size at first maturity. The results suggest that the spotted rose snapper has two well-defined reproductive periods - from October to December and March to May. These periods were closely related to temperatures that ranged from 29 to 31°C. In addition, according to the monthly monitoring of the oocyte diameter density distribution, it is suggested that spotted rose snapper in the region could participate in up to three spawning events during the reproductive season, with gamete development occurring throughout most of the entire study period. The first size at maturity was a total length (TL) of 33.49 cm (confidence interval = 30.95-36.14 cm). This information is important for sustainable fishery management and provides a baseline for future research.

Diferentes métricas de biodiversidad se deben explorar para evaluar de manera más eficiente los cambios observados en las comunidades. Sin embargo, el desempeño de distintas métricas de biodiversidad no ha sido explorado en el golfo de Batabanó, lo que puede dificultar la selección de índices adecuados para el monitoreo ambiental. Para solventar esta problemática seis métricas de biodiversidad (riqueza de especies, equidad de Pielou, diversidad de Shannon, diversidad taxonómica, distintividad taxonómica promedio y variación en la distintividad taxonómica) fueron comparadas para determinar su congruencia y respuestas ante variables abióticas (salinidad, temperatura, turbidez, profundidad) y factores (zonas y años). Los resultados obtenidos por correlaciones entre las métricas y sus respuestas a las variables abióticas y factores analizados mostraron complementariedad entre la riqueza de especies, equidad de Pielou, diversidad de Shannon, distintividad taxonómica promedio y variación en la distintividad taxonómica, no siendo así para la diversidad taxonómica. Según los resultados de este trabajo, se sugiere el uso de la riqueza de especies y las métricas de distintividad taxonómica ∆+ y Λ+ para evaluar la calidad ambiental del golfo de Batabanó. Además se deben evaluar sus desempeños en otros grupos de organismos.

El caracol Megastraea undosa forma parte de las pesquerías de recursos bentónicos económicamente importantes de la costa occidental de Baja California Sur, México. Los estudios sobre su densidad y estructura de tallas son importantes debido a que forman parte de las evaluaciones de stock en apoyo al manejo de su pesquería. El objetivo de este trabajo fue determinar las variaciones espacio-temporales de la densidad y estructura de tallas del caracol M. undosa en la costa occidental de Baja California Sur, México. Se determinó la estructura de tallas por sitio de muestreo y se analizó con base en la talla mínima legal y por zona de pesca. En el análisis espacial, la densidad (ind. m-2) y talla promedio se analizaron por estrato de profundidad y zona de pesca. El análisis temporal, densidad y talla promedio fueron analizadas por estrato de profundidad, únicamente para la zona 3, en el periodo comprendido desde 1999-2014. Los resultados demostraron diferencias espaciales de la densidad y talla promedio del caracol M. undosa en la costa occidental de Baja California Sur, y en el sitio de pesca más sureño dominaron las tallas pequeñas. Se discuten las variaciones espacio-temporales de la densidad y estructura de tallas en función de la disponibilidad de macroalgas, así como de la temperatura superficial del mar y las surgencias estacionales. El conocimiento del comportamiento espacio-temporal de la talla y densidad de M. undosa servirá de base para su futuro manejo, con base en un enfoque biológico o bioeconómico para el establecimiento de puntos de referencia.

A structural map of the value chain of the grouper fishery that operates in YucatAn was integrated and characterized using official catch data, prices and information collected through interviews with key actors involved in the productive chain of this fishery in. We identified the actors involved in the chain, their role across the chain, and the market trends that influence the prices of the product. We present the national and international trends on demand and the main destinations of the product captured in Yucatan. The highest demand resides in fresh, frozen and filleted product, the latter especially for export to the United States. Nationally, five states located in the central and northern region of the country are those of higher demand, but local demand in Yucatan and other touristic destinations on the peninsula remains important. Informal markets and their participation in the production chain are highlighted. With the arrival of the Sars-Covid 19 health contingency, changes were observed in the structure of the chain, price and high opportunity costs due to inactivity and price changes. The fishery shows signs of high fishing pressure and the high demand for the product does not change despite these patterns, so collective actions are required to improve the conditions of the fishery and balance the benefits it generates across the chain. Keywords: Production chain, grouper, markets, export and imports, Yucatan peninsula.