Estimación del crecimiento individual en elasmobranquios: la inferencia con modelos múltiples

Elasmobranchs play an important role in marine ecosystem and worldwide fisheries. Accurate and quantitative description of growth is crucial in modeling the demography and fisheries stock assessment. This study reviews the quantitative methods (asymptotic, non-asymptotic, and generalized), algorithms, and criteria for the model selection applied for growth modeling in elasmobranchs. We analyzed and contrasted the criteria for model selection, mainly between model selection using r2 and information theoretic approach. In marine organisms, the Akaike information criterion (AIC) has been frequently used as a measure of the relative goodness of fit of different growth models, applied to data from different species such as: Dasyatis americana, Carcharhinus acronotus, Carcharhinus plumbeus, Heterodontus portusjacksoni, Malacoraja senta, Mustelus asterias and Mustelus mustelus. We suggest the use of AIC to select the best growth model in elasmobranchs studies.Los elasmobranquios tienen un papel importante en el ecosistema marino y en las pesquerías mundiales. La descripción precisa y cuantitativa del crecimiento es crucial para evaluar las poblaciones. Este estudio revisa los métodos cuantitativos (asintóticos, no asintóticos y generales), para la modelación del crecimiento individual en elasmobranquios. Se analizan algoritmos y se comparan criterios para la selección de modelos, como los criterios de r2 y la teoría de la información. El criterio de información de Akaike (AIC) ha sido usado frecuentemente como una medida relativa de la bondad de ajuste de diferentes modelos de crecimiento, así como en la comparación de modelos aplicados a datos de diferentes especies: Dasyatis americana, Carcharhinus acronotus, Carcharhinus plumbeus, Heterodontus portusjacksoni, Malacoraja senta, Mustelus asterias y Mustelus mustelus. Se sugiere el uso del AIC para seleccionar el mejor modelo de crecimiento en estudios de elasmobranquios

Seagrass Halodule wrightii as a new habitat for the amphioxus Branchiostoma californiense (Cephalochordata, Branchiostomidae) in the southern Gulf of California, Mexico

The first record of the amphioxus Branchiostoma californiense on seagrass patches of Halodule wrightii in the Gulf of California is reported. Sixty individuals (19 males, 18 females, and 23 undifferentiated) were collected in May 2017 at Bahía Balandra, Gulf of California, from subtidal seagrass patches at a depth of 0.5 m at low tide. The length and weight ranged from 15.88–28.44 mm and from 0.01–0.11 g for females and 11.7–27.9 mm and 0.01–0.09 g for males, respectively. The minimum size of sexually mature individuals was 11.70 mm for males and 15.88 mm for females; 62% of the specimens were sexually mature. Analysis of the total length-weight relationship suggested an allometric growth pattern among females, males and undifferentiated individuals, whereas an analysis of the entire sample suggested an isometric growth pattern. Typical and additional morphological characters were used to identify the amphioxi. High morphological variability between individuals was found, suggesting the presence of several morphotypes. Branchiostoma californiense had been previously reported as exclusively associated with bare sandy areas, but our study shows that this species can also be found in seagrass patches, using them as breeding and feeding grounds. Thus, seagrass patches are evidenced as suitable habitats for amphioxus

Age and growth estimates of the jumbo flying squid (Dosidicus gigas) off Peru

Mantle length (ML) and age data were analyzed to describe the growth patterns of the flying jumbo squid, Dosidicus gigas, in Peruvian waters. Six non-asymptotic growth models and four asymptotic growth models were fitted. Length-at-age data for males and females were analysed separately to assess the growth pattern. Multi-model inference and Akaike's information criterion were used to identify the best fitting model. For females, the best candidate growth model was the Schnute model with L∞ = 106.96 cm ML (CI 101.23–110.27 cm ML, P < 0.05), age at growth inflection 244.71 days (CI 232.82–284.86 days, P < 0.05), and length at growth inflection 57.26 cm ML (CI 55.42–58.51 cm ML, P < 0.05). The growth pattern in males was best described by a Gompertz growth model with L∞ = 127.58 cm ML (CI 115.27–131.80 cm ML, P < 0.05), t0 = 21.8 (CI 20.06–22.41, P < 0.05), and k = 0.007 (CI 0.006–0.007, P < 0.05). These results contrast with the growth model previously reported for D. gigas in the region, where the growth pattern was identified as non-asymptotic

Interaction Between Marine Fauna and the Small Pelagic Fishery in the Coastal Environment of the Gulf of California, Mexico

The first steps have been taken to analyze the effects of small pelagic harvests on the Gulf of California ecosystem. The primary goal of this study was to estimate the latitudinal differences in regionalized baselines of endangered and threatened marine species attracted to a purse seine in a Mexican fishery of small pelagic fish. We also analyzed the spatial patterns in fishing effort in the Gulf of California. Seven zones were analyzed in the Gulf of California, including the east and west coasts, and a total of 3,051 fishing sets were analyzed during January 2013 and July 2014; the data provided a comprehensive picture of the distribution of the fishing effort, small pelagic fishes harvested, and the presence of species attracted to the fishing sets. The region in the upper Gulf of California showed a low presence of individuals, and the east coast recorded more sightings than the west coast; consequently the fishing effort was mainly distributed in the east coast. The number of individuals for several species sighted and counted by fishing set was used for each zone in the Gulf of California, and a conservative baseline based on the Pennington estimator was computed. It provided an average value of endangered and threatened marine species attracted to a purse seine for each zone. The Pennington estimator is recommended due to the precision of the confidence intervals and the nature of the uncertainty in the data collection based on sightings