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Scientists offer basis for South Pacific bonito aquaculture in Chile
June 1, 2021 By Ruby Gonzalez
Two studies on South Pacific bonito (Sarda chiliensis) broodstock development and larval culture may finally give Chile the push it needs to get started with the commercial aquaculture of the species.
The studies investigated the first natural spawning of wild-caught premature animal in a recirculating aquaculture system (RAS), the first biological embryonic development until hatching and the morphology and allometric growth of larval development.
“The recently published studies are the basis for the beginning of the aquaculture of this species. We hope that the internal policies of our country consider this resource as necessary to leverage money and we can start the commercial cultivation of this species,” Renzo Pepe-Victoriano, director of the Masters Program in Aquaculture at Universidad Arturo Prat in Arica, Chile, told Hatchery International.
The first study is called “First natural spawning of wild-caught premature south pacific bonito (Sarda chiliensis chiliensis, Cuvier 1832) conditioned in recirculating aquaculture system and a descriptive characterization of their eggs embryonic development.”
The second is “Descriptive morphology and allometric growth of the larval development of Sarda chiliensis chiliensis (Cuvier, 1832) in a hatchery in northern Chile.” Both are by Pepe-Victoriano et. al. and were published in Aquaculture Reports.
South Pacific bonito is a small tuna that is rich in omega-3 and characterized by fast growth. It is distributed from Mancora, Peru, to Talcahuano, Chile.
First-generation broodstock from wild-caught juveniles, each weighing less than one kilogram, conditioned to spawn at the RAS facility of La Capilla, located 10km south of Arica. Fish were captured between November 2011 and January 2012, and a spontaneous spawning happened in January 2013.
“We do not use any hormones,” he said. “The fish spawned naturally in the second summer in captivity, as well as the Atlantic bonito species (Sarda sarda). We have to take into account that as they are extracted from the natural environment and we want them to form a stock of reproducers, it is necessary to consider some things.”
He stressed the importance of minimizing stress the fish. Barbless hooks were used in catching fish so that the snout will not be damaged and not stress them. Low density of no more than four fish per 1,000-litre holding tank was maintained during sea and land transportation.
In the conditioning pond, there should be fish already accustomed to captivity when new fish is introduced so that the latter adapts mainly to the capture of food. “At the beginning, fresh food should be given and later on, pellets for broodstock should be given,” he said.
Twenty-one juveniles were stocked in the 75-cubic-metre conditioning pond at a density of one kg/m3. Water flow of not less than 100 litres per minute must be maintained.
Buoyant eggs were manually collected from the culture tank using 300-μm-mesh plankton net. The collected eggs were then separated according to their embryonic development. These were then transferred to three 300 x 150 x 200mm – aquariums with continuous aeration. All were placed inside a climate-controlled warm room. Incubation density was between 2000 and 2500 eggs per l L-1 Using airstone diffusers, aeration was provided to each aquarium at a rate of 0.1/ L-1.
“Thirty-one embryonic stages were characterized over about 72 hours until eggs began to hatch. Five periods of embryonic were distinguished: morula, blastula, gastrula, neurula, and metamery… These are the first embryonic development studies conducted with eggs naturally spawned from wild-caught South Pacific bonito,” the authors said.
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