Adapting to a new reality: Shrimp nurseries as the new normal

The article written by Mr. Olivier Decamp was very informative and well written. I will add to some of his points from my experience in managing the only shrimp farm in Nigeria of West Africa. We culture P.monodon. mom don't in our farm and adopt a nursery system before stocking the seeds into our ponds. We do stock end on our seeds anywhere from a stocking density of 600 to 1200/M2 in our HDPE lined Nursery ponds. The top of the nursery tanks are covered with Orchid nets to prevent direct sunlight penetrative. Aeration is blower based. We found that Nutritional quality of feeds do matter to a great extend in terms of shrimp fry size as well as survival. Higher protein diets of 42% and above have shown to give better growth of the fry in the final stages. Also the correct particle size of the feeds and attractability also plays a major role in improving pond conditions and and voiding wastages. We also apply probiotics on a regular basis along with added immunostimulants in the feeds. Bacterial populations are always kept at a desired level by regular monitoring. The final sizes of Juveniles varied from 0.9 gm to 1.5 gms after 30 days of nursery phase depends on the stocking density.

Thank you very much for your comments and the description of your system. We have experience dealing with nursery systems with both vannamei and monodon. I would be interested in discussing it further.

Regards,
Olivier

Previously in India there were earthern nursery ponds, where the farmers used to rear for 30 days, to reach up to 2.5 to 3 gms, then stocked in grow out ponds. This practice helped them to successfully assess the total biomass in the grow out ponds, but could not help in additional growth or arrest of disease.
Providing nurseries with pvc or cement tanks increases cost of production and need to think whether is viable with the variable prices of export shrimp.
It is true that shrimp will attain full immunity or organ development after reaching sub adult stage.Any high quality feed is not equal to the little availability natural live feed available in pond water and soil. I feel the introduction semi hatchery type nursery systems is to answer early most mortalities before 30 to 35 days instead of working root causes for the disease spread. I also feel our conclusions are mostly based on assumptions than determinations.we developed tools to identify disease but not much work on arresting the disesae.

This new reality sort of starts off on the right footing. But after the nursery stage the ideas are abandoned for a more conventional system. As the nursery stage is towards a more natural feeding system and this works because the species is receiving an improved nutrient supply via a normal food chain at least in part, the next stage is really to increase this food chain in variety and form all of which should be understood by any marine zoologist. The food items that are made available can be increased to enhance the feeding regime in this environment. Intensification does not have to mean abandoning a natural food chain as the feeding system that works at the nursery stage. using the same principles for the grow out phases is ignored for a more artificial system that is inherently flawed owing to the problems everyone is experiencing. Produce more natural food for the species on site in their own dedicated environment. This may well lead to a larger unit and less grow out space but it will improve survival and performance. The food chain enhancement program becomes part of the production system, this food is free and can be produced all the time whether or not the grow out ponds are inhabited or not. This part of the system has always been missed out in favor of the artificial and in itself creates the problems. If a fish is sick then its environment needs to be changed to one that suits the species. If it is good enough for the nursery stages it is good enough for the rest of the system. That this philosophy is not part of the taught system, it has been ignored without good reason. I cannot see continuing down the same old path has solved the problems in any part of intensive aquaculture. One may think that reducing production will impact on the bottom line, this will not be found to be the case, it is only a theory, and the evidence is far too plain to see.