Modelling Early Growth of Totoaba macdonaldi (Teleostei: Sciaenidae) under Laboratory Conditions

Abstract

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.

The Fractal Approach to Describe Growth of Farmed Marine Species: Using Double and Triple Logistic Models

“…In this analysis, it appears that there are three logistic harmonics represented in the triple logistic model. According to reference [14], the somatic growth of totoaba under laboratory conditions exhibited two inflection points: between 16 to 18 days post-hatching (DPH) and another 31 to 33 DPH. The exp-Schnute model accurately captures the major characteristics of the growth pattern of this species, except in the last days of the culture period, which requires a more detailed analysis.…”

“…The authors explain these inflections in terms of the development of the digestive tract and the success of weaning. In [14], the authors note that the second turning point occurred when feeding with a formulated diet began at 31 DPH, which stimulated growth between 31-35 DPH.…”

“…Nowadays, testing multiple models and statistical approaches with various size error structures is much easier. In [14], the authors modified Schnute's original model in an attempt to represent the growth of totoaba larvae. The study used the exp-Schnute model, which was found to be the most effective, but was unable to accurately represent the last two days of the culture period.…”

“…The growth data analyzed in this study are from an oyster culture (Crassostrea corteziensis), a commercial shrimp culture (Penaeus vannamei), and growth of totoaba (Totoaba macdonaldi) larvae under laboratory conditions, which have preexisting published studies with details on cultivation period, feeding procedures, and husbandry techniques [14][15][16]. In this study, the focus is on modeling the growth by means of new approaches not used in the original studies.…”

“…Under laboratory conditions, it has been observed that the growth pattern of early stages of aquatic species follows a quasi-sigmoid curve with two inflection points [13,14], which suggests a double logistic growth model. However, in commercial aquaculture, species can experience changes in feeding type that can influence growth across multiple seasons, making a triple logistic model a potential alternative.…”