European advancements in wreckfish farming
Vital data on this high-value species’ reproduction and larval-rearing protocols gain critical mass
Simultaneous five-year research work in Europe has cleared most of the stumbling blocks related to wreckfish (Polyprion americanus) farming.
“Our challenge has been achieved almost entirely and we hope to continue working to consolidate the culture of the wreckfish,” stated Blanca Alvarez-Blazquez in her presentation titled, The wreckfish as a potential new species for the aquaculture in the Eastern Atlantic.
This was one of many presentations which focused on broodstock and larval culture, at the Wreckfish Know-How Transfer Workshop in July 2018 in Vigo, Spain.
The projects, which commenced in 2015, are partially funded by the European program, Diversify, which sought “to advance the knowledge and its practical application in the culture of new and emerging finfish species, in order to satisfy an expanding European market for a variety of sustainable fresh fish.”
Results and updates from 2015-2018 were presented at the workshop.
Wreckfish has been included in the list of new and emerging species for aquaculture in the Eastern Atlantic. The selection was based on economic, biological and sustainability criteria.
It commands a high market price and has limited fisheries landings.
Fast-growing, the records posted a growth of 1.7 kg to 4.8 kg in 283 days. It could grow two-meters-long and 100 kg.
It has late reproductive maturation, which allows commercialization before maturity and avoids problems linked to maturation such as reduction in growth. It also has an extended pelagic juvenile phase.
Just as it is easy to manipulate in captivity, it likewise acclimatizes easily to captivity.
Information, however, was scarce on reproduction control, spawning preferences, methods of spawning induction, larval rearing protocols and juvenile production.
Dry diet has been connected to fecundity and spawning. “Relative fecundity and number of spawns per female have been increasing in females fed with dry feed over the years, from 2015 to 2018,” stated Fatima Linares in her presentation titled Wreckfish broodstock nutrition.
The broodstock, maintained in participating research centers, reproduced through natural and spontaneous spawning, spawning induction with exogenous hormones (GnRHa) and stripping of the mature males and females.
By 2018, save for a very small percentage of GnRHa induction, all reproduction was through spontaneous spawning.
“During these last years, the number of spontaneous spawns were increased, and the number of induced spawns was reduced. The reason is probably the better adaptation of the females to the captive conditions and the promotion of the natural maturation cycle, resulting in not only vitellogenesis, but also spontaneously oocyte maturation,” Blazquez cited in another presentation, Reproduction of wreckfish in captivity and induction of spawning with GnRHa.
Low feeding rates were observed from March to July, the spawning season. High feeding rates were recorded during autumn.
In yet another presentation, Advances in wreckfish larval culture, Blazquez looked at developing a larvae culture protocol and studying the influence of different sea water temperatures.
A milestone was reached in 2018. “This was the first time in the project that we succeeded in producing juveniles weaned to inert food, and it signifies a milestone in the efforts to produce wreckfish under aquaculture conditions,” the presentation stated.
Work continued after the results were released. Among the concerns addressed were larval malformation and higher survival rates. Per the larval culture presentation, “Changes are being made in incubation, embryogenesis and larval husbandry that can be decisive to avoid the problem of malformed larval and achieve greater survival.”
Also in the list of choice of new and emerging species are greater amberjack, pikeperch, meagre, grey mullet and Atlantic halibut.
“Among the new species to be exploited for commercial aquaculture, wreckfish is one of the most interesting ones. It is necessary to continue researching reproduction, larval culture and ongrowing so that in five to six years, the first specimens of this species arrive on the market,” Jose Luis Rodriguez-Villanueva stated during a presentation.
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