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Modeling individual growth in marine species for aquaculture encounters many difficulties when the species pauses its growth but resumes its later after the disrupting phenomenon (environmental or physiological) has been overcome. Seasonal or oscillatory growth has been addressed by modifying existing models, such as von Bertalanffy and Gompertz, to include an oscillatory component in this study. The novelty of this study lies in the fractal approach used to analyze growth using multiple logistic functions. Three commercially farmed marine species were studied, including shellfish, crustacea, and finfish. The oscillatory version of the von Bertalanffy model as well as double and triple logistic functions were used for analysis. The best model was selected using the information theory, Specifically the Akaike criterion (AIC) and the Bayesian criterion (BIC). Normal and log-normal distributions of error were assumed. The triple logistic model with log-normal distribution in the error structure was found to be the best model to describe the growth pattern of the three commercially farmed species as it obtained the lowest AIC. Overall, this study concludes that the fractal approach is the most effective way to describe growth in farmed species, including shellfish, crustacean, and finfish.

In recent years, the application of silver nanoparticles (AgNPs) as antibacterial compounds has been widely used in human and veterinary medicine. In this work, we investigated the effects of AgNPs (Argovit-4®) as feed additives (feed-AgNPs) on shrimp (Litopenaeus vannamei) using three different methods: 1) chronic toxicity after 28 days of feeding, 2) Effects against white spot syndrome virus (WSSV) challenged by oral route, and 3) transcriptional responses of immune-related genes (PAP, ProPO, CTL-3, Crustin, PEN3, and PEN4) following WSSV infection. The results showed that the feed-AgNPs did not interfere with the growth and survival of shrimp. Also, mild lesions in the hepatopancreas were recorded, proportional to the frequency of the feed-AgNP supply. Challenge test versus WSSV showed that feeding every 7 days with feed-AgNPs reduced mortality, reaching a survival rate of 53%, compared to the survival rates observed in groups fed every 4 days, daily and control groups of feed-AgNPs for the 30%, 10%, and 7% groups, respectively. Feed-AgNPs negatively regulated the expression of PAP, ProPO, and Crustin genes after 28 days of treatment and altered the transcriptional responses of PAP, ProPO, CTL-3, and Crustin after WSSV exposure. The results showed that weekly feeding-AgNPs could partially prevent WSSV infection in shrimp culture. However, whether or not transcriptional responses against pathogens are advantageous remains to be elucidated.

The vaquita (Phocoena sinus) is considered the world’s most endangered marine mammal. It is the smallest member of the porpoise family endemic to the upper part of the Gulf of California. The current population is estimated at less than 30 individuals. The primary reasons for the species decline includes limited habitat and incidental mortalities associated with illegal gillnet fishing activities. Since 2008, the Mexican government has taken environmental and economic actions to protect the vaquita’s focusing in reducing by-catch deaths to zero. In 2015, a federal Agreement decreed by the Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación (SAGARPA in Spanish) prohibited the use of any fishing gillnets for two years, affecting severely the local human communities because in the region the coastal fisheries represent 40% of the regional PIB, besides that 50% of the local inhabitants are devoted to this activity. Recently, an economical compensation is giving to the fishing permits owners if they do not continue with their fishing activities. However none of this actions and agreements have considered social and economic solutions for the local inhabitants of this region, which includes three communities: San Felipe, Golfo de Santa Clara and Puerto Peñasco. If there is not enacted a change of paradigm of the conservation programs, focusing in the wellbeing of the local fishing communities then the vaquita could be the second marine mammal species to disappear due to human activities.