Search Results (6)

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. Full article

Finding strategies to use the swim bladder of farmed totoaba (Totoaba macdonaldi) is of the utmost need to reduce waste. Fish swim bladders are rich in collagen; hence, extracting collagen is a promising alternative with benefits for aquaculture of totoaba and the environment. The elemental biochemical composition of totoaba swim bladders, including their proximate and amino acid compositions, was determined. Pepsin-soluble collagen (PSC) was used to extract collagen from swim bladders, and its characteristics were analyzed. Alcalase and papain were used for the preparation of collagen hydrolysates. Swim bladders contained 95% protein, 2.4% fat, and 0.8% ash (on a dry basis). The essential amino acid content was low, but the functional amino acid content was high. The PSC yield was high, at 68% (dry weight). The amino acid composition profile, electrophoretic pattern, and structural integrity analyses of the isolated collagen suggested it is a typical type-I collagen with high purity. The denaturalization temperature was 32.5 °C, probably attributable to the imino acid content (205 residues/1000 residues). Papain-hydrolysates (≤3 kDa) of this collagen exhibited higher radical scavenging activity than Alcalase-hydrolysates. The swim bladder from the farmed totoaba could be an ideal source to produce high-quality type I collagen and may be considered an alternative to conventional collagen sources or bioactive peptides. Full article

The totoaba (Totoaba macdonaldi) is a sciaenid (croaker) fish endemic to the Gulf of California with high commercial importance. Because it was considered at risk of extinction (since 2021 it was reclassified as vulnerable by the IUCN), and aquaculture procedures were developed for restocking and commercial purposes. The present study was conducted with the hypothesis that the early stages of totoaba present depensatory individual growth and an observed variance-at-age modelling approach is the best way to parametrize growth. Ten models were tested including asymptotic, non-asymptotic, exponential-like, and power-like curves including a new one that represents a modification of Schnute’s model. The model that best described the growth trajectory of larval and early juveniles of T. macdonaldi in a controlled environment is a sigmoid curve with two inflexions, related to changes in the feeding regime. Full article

T. macdonaldi is a carnivorous species endemic to the Gulf of California. Indiscriminate exploitation has put totoaba at risk, inducing the development of aquaculture procedures to grow it without affecting the wild population. However, aquafeeds increasing cost and low yields obtained with commercial feeds have motivated researchers to look for more nutritious and cheaper alternatives. Soybean (SB) is the most popular alternative to fishmeal (FM); however, antinutritional factors limit its use in carnivorous species. In this study, we analyzed B. subtilis 9b probiotic capacity to improve growth performance and health status of T. macdonaldi fed with formulations containing 30% and 60% substitution of fish meal with soy protein concentrate (SPC). In addition, we investigated its effect on internal organs condition, their capacity to modulate the intestinal microbiota, and to boost the immunological response of T. macdonaldi against V. harveyi infections. In this sense, we found that T. macdonaldi fed with SPC30Pro diet supplemented with B. subtilis 9b strain and 30% SPC produced better results than SPC30C control diet without B. subtilis and DCML commercial diet. Additionally, animals fed with SPC60Pro diet supplemented with B. subtilis 9b strain and 60% SPC doubled their weight and produced 20% more survival than SPC60C control diet without B. subtilis. Thus, B. subtilis 9b improved T. macdonaldi growth performance, health status, modulated intestinal microbiota, and increased animal’s resistance to V. harveyi infections, placing this bacterium as an excellent candidate to produce functional feeds with high levels of SPC. Full article

Obtaining the best possible estimates of individual growth parameters is essential in studies of physiology, fisheries management, and conservation of natural resources since growth is a key component of population dynamics. In the present work, we use data of an endangered fish species to demonstrate the importance of selecting the right data error structure when fitting growth models in multimodel inference. The totoaba (Totoaba macdonaldi) is a fish species endemic to the Gulf of California increasingly studied in recent times due to a perceived threat of extinction. Previous works estimated individual growth using the von Bertalanffy model assuming a constant variance of length-at-age. Here, we reanalyze the same data under five different variance assumptions to fit the von Bertalanffy and Gompertz models. We found consistent significant differences between the constant and nonconstant error structure scenarios and provide an example of the consequences using the growth performance index ϕ′ to show how using the wrong error structure can produce growth parameter values that can lead to biased conclusions. Based on these results, for totoaba and other related species, we recommend using the observed error structure to obtain the individual growth parameters. Full article

Sediment discharges from rivers play a key role in downstream ecosystems, both for ecosystem morphology (e.g., deltas) and productivity. However, the construction of dams and river regulation dramatically alter sediment transport. Currently, the Colorado River delta is one of the most transformed deltas in the world and, most years, no flow reaches the Gulf of California. In this study, we used satellite images for the observation and measurement of coastal water turbidity in the Upper Gulf of California (UGC) and Colorado River Delta (CRD). Specifically, we used the Earth-observing Satellites (in French Satellites Pour l’Observation de la Terre, SPOT) high spatial resolution satellite. We processed images of the wavelength 2 (S2610-680) from the period between 2008 and 2013 in the Biosphere Reserve area. Results showed that suspended material and high turbidity predominate in the CRD and intertidal zones of the UGC. High and very high turbidity values were due to two opposite coastal transport components along the Sonora and Baja California coasts. The high spatial resolution of the SPOT sensor effectively allowed the sediment transport gradients and the accumulation zones to be located in a highly variable area. This information provided by SPOT images can be very valuable for management decisions such as the amount of ecological flow that needs to be released. This area is the habitat of endangered species, such as totoaba (Totoaba macdonaldi) and vaquita (Phocoena sinus), that are seriously affected by the loss of estuarine conditions. High resolution satellite images can help to quantify the true extent of corrective measures. Full article