Bioeconomic profitability analysis of tropical gar (Atractosteus tropicus) grow out using two commercial feeds

Abstract

This study compared survival, growth, feed conversion rate (FCR) and harvested biomass of two commercial strains of tilapia (Oreochromis niloticus) cultivated in Mexico: Spring Genetic-Benchmark Holding® originated from the Genetically Improved Farmed Tilapia GIFT (Genebank: GIFT GU477624.1) and strain B from different line-breeding (Genebank: Philippines GU477626.1, Guangdong GU477627.1, and America GU477628.1). The study was performed in six geomembrane ponds (2,520 m 3 ; 30×40×1.5 m) with supplementary aeration, in Los Pozos farm, El Rosario, Sinaloa, Mexico. In July 2016, 26,762 ± 170 fries of each strain (2.9 ± 0.1 g and 5.4 ± 0.2 cm) were cultivated in the nursery under similar conditions in triplicate at 11 ind m-3 for 34 days; then, they were transferred to the grow-out ponds and fed with 30% crude protein balanced feed (Purina®) at a rate of 12% live weight day-1 in three rations (07:00, 12:00 and 17:00 h) for 123 days. The results showed that Spring had a lower variation coefficient (VC) and higher survival, growth rate in weight, initial and final size, and harvested biomass. Survival was 30.7% greater in Spring and doubled harvested biomass (Spring 10 ± 0.8 t ha-1 vs. B strain 5 ± 4.7 t ha-1). Sixty percent of the Spring population reached a commercial weight of 500 g in day 123th of cultivation compared with 20% of B population in the same period. Except for FCR, VC was lower in the Spring strain. Differences in productive parameters were probably due to the genetic selection programs at which both strains were subjected.

Effect of stocking density on growth, survival and condition factor in tropical gar (Atractosteus tropicus Gill, 1863) juveniles

“…The density of the fish varies according to the stage of growth in which it is; at present, the studies conducted indicate that the larger and heavier the individuals, their density should decrease to preserve optimal growth and avoid problems due to competition. Considering juvenile fish (0.5 to 150 g) with approximately 21 to 270 days after hatching , densities used with this genus have been reported during early stages from 300 ind m -3 on Atractosteus tropicus (Martínez-Cárdenas et al, 2018), to 500 ind m -3 on A. spatula (Clay, 2009), with a decrease to 20 ind m -3 on A. tropicus of 100 g, and reaching 10 ind m -3 as they approach 400 g (Palma-Cancino et al, 2019). Perschbacher (2011) of culture with 300 ind m -3 reported growth and an SGR similar to the maximum density evaluated in this study without adverse effects, similar to Mendoza-Alfaro et al (2010) on A. spatula, who reported a growth of 3.18 mg d -1 for juveniles, resulting in a weight gain of approximately 22 g for fish with an initial weight of 5 g.…”

Ancestral Maya domesticated waterscapes, ecological aquaculture, and integrated subsistence

“…The first studies of Maya canals and raised fields took place in this region, including the Candelaria River watershed and experimental raised fields ( camellones ) in swamps (Pérez Sánchez 2007). Recent projects here increased attention to Maya aquaculture and highlight the importance of Maya aquatic food resources (Gómez-Pompa et al 1982; Martínez-García et al 2022; Palma-Cancino et al 2019). For instance, fisher-farmers at Tucta, Tabasco, have told me that the large-scale canals among their camellones provide much aquatic and terrestrial foods.…”

Cost-benefit analysis for the production of juveniles of tropical gar (Atractosteus tropicus Gill): a comparison of four feeding schemes.

“…Aquaculture of this species has had important advances since the beginning of this century as a fishing alternative (Márquez et al, 2006). Its reproduction in captivity is known (Márquez et al, 2013), as well as its enzymatic activity during development (Guerrero-Zárate et al, 2014;Frías-Quintana et al, 2015), it's fattening and production costs during this stage (Palma-Cancino et al, 2019b), and the design of diets and feeding strategies during their larval development and pre-juvenile production (Frías-Quintana et al, 2010, 2016Nieves-Rodríguez et al, 2018;Palma-Cancino et al, 2019a).…”

“…The energy costs (C E ) were calculated by estimating the total Kwh expenditure of the pump and thermostat and multiplying them by the current rate established by the Comisión Federal de Electricidad (Federal Electricity Commission, CFE) for 2021; the labor costs C L , consisting of a wage for a worker, using the daily minimum wage as a reference, according to that established by the Diario Oficial de la Federación (Official Journal of the Federation, DOF, 2020), which currently consists of 5.37 USD daily for 50 days (duration of the culture from spawning). The broodstock maintenance cost (C BM ) is a fixed cost, equivalent to 18.91 USD, estimated for the maintenance of five males and one female for the duration of larviculture, fromPalma-Cancino et al (2019b).…”

“…To estimate the breakeven point for the number of pre-juveniles (BQ), the previously mentioned selling price per unit of SpU0.38 USD was used. The fixed costs (FC) were calculated with the proportion of the annual depreciation of the 50-day cropping system, estimated at 61.69 USD, based on the system described byPalma-Cancino et al (2019b); and the sum of the C E , C L , and C BM for 50 days, equivalent to 297.14 USD, soFC358.83 USD. The equation used was the following modified from Sathiadhas et al (2009):…”