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Spawning TanksA Discussion from the Shrimp List
This discussion on spawning tanks took place on the Shrimp List (see page ???) in April 2005.
Darryl Jory (firstname.lastname@example.org): How common is the use of large (2 to 4 meters in diameter), communal spawning tanks with Penaeus monodon? Are large tanks used for spawning P. monodon in Thailand, Indonesia, India, Myanmar and Vietnam?
Hervé Lucien-Brun (email@example.com): Oui, large maturation tanks (4 to 6 meters in diameter)—circular or square—work quite well with monodon. Most of the hatcheries in Madagascar use large maturation tanks. In Indonesia and in Myanmar, I know of at least two hatcheries that use large maturation tanks, and they are similar to ones I’ve seen in Ecuador with Penaeus vannamei. For more details or pictures, you can contact me off list.
Michel Autrand (firstname.lastname@example.org): I think Darryl is asking about spawning tanks, not maturation tanks. Individual spawning tanks (600 to 800 liters, with conical bottoms) are used in all five monodon hatcheries in Madagascar with no problems.
Maturation can be conducted in square or rectangular tanks of several square meters (frequently between 10 to 20 m2).
Hervé Lucien-Brun (email@example.com): We don’t like large, communal spawning tanks because you don’t have the opportunity to separate the good spawns from the bad spawns. We look at every spawn and reject the ones with bad hatching rates or deformed nauplii. I think selection of spawns is one of the keys to producing good larvae. In large communal spawning tanks, it’s not possible.
M. Chandrasekar (firstname.lastname@example.org): Introduced by Taiwan and Thai technicians, communal or mass spawning used to be a regular practice in India, but now, most hatcheries use individual spawning tanks. Mass spawning continues to be used in Iran with Penaeus indicus.
Alec Forbes: Large tanks for communal spawning were very much in vogue when I had my small hatchery in Ang Sila, Thailand, back in the mid-1980s. I personally preferred the Galveston Method and kept one, two or three spawners in a relatively small tank, and I continue this practice today, but I do recall in Thailand that very large square concrete tanks were used to maintain ablated spawners. They would all spawn in the first two nights, and you ended up with a large quantity of mixed naups. I also saw this in Myanmar and China.
Anil Ghanekar (email@example.com): Large spawning tanks used to be the practice at some nauplii centers in India, but the trend is changing now. Many hatcheries prefer to use individual spawning tanks because it makes it easier to screen for viruses.
Todd Blacher (firstname.lastname@example.org): It is actually very common in Asia for maturation systems to have communal spawning tanks. Gravid females are placed in a large, male-occupied tank (sometimes up to 30 or 40 tons). Females are checked a few times for copulation success and then moved to another tank of equal size for the actual spawning. Once spawning is complete, the females are removed and the eggs are left in the same spawning tank for the hatching process. This technique is common in many Asian countries. The quality issues, however, are real. Most of the facilities that do it this way are not producing nauplii for their own farms, but for sale to other farms. There is no way to guarantee the quality of the spawns because they are all mixed together.
Laurence (email@example.com): We use mass spawning for P. indicus because it significantly reduces labor requirements, and it is easy to harvest and treat a large batch of nauplii. Admittedly, there is less control of individual spawns, but in commercial applications, I wonder how much attention is really paid to each spawn. Do the proponents of individual spawning tanks really investigate every spawn for nauplii quality? If so, what is the handling protocol carried out on every single spawning tank?
Also, with monodon, one female can produce 1,000,000 nauplii. Indicus only produces about 80,000 nauplii, so we put 10 or 15 together and get the same number of nauplii that you would get from one large monodon.
Adam Body (firstname.lastname@example.org): We also use communal spawning with indicus in northern Australia.
Iván Cereceda (email@example.com): The same for us in Ecuador. But, if you have a genetics program, you should use individual spawning tanks. If not, it’s cheaper to use communal spawning.
Adam Body (firstname.lastname@example.org): In mid-2003, anticipating lower shrimp prices in Australia because of the predicted onslaught of P. vannamei imports, we initiated a research and development project on indicus at our farm in the Northern Territory, guessing that indicus would be cheaper to grow than monodon. Flying solo, it took us about a year to get into production. No one in Australia knew anything about indicus farming, but we did find that indicus was very easy to work with in the hatchery.
We developed our own communal spawning method for indicus, and it worked extremely well. We selected superior shrimp from the growout ponds, marked them with injectable polymer tags, and then put 70, unilaterally ablated females at a time in a communal spawning tank.
We are beginning to scale-down shrimp farming and scale-up fish farming (barramundi) because imports of vannamei from Asia have lowered local prices so much that it’s difficult to make money farming shrimp.
Ram Raj (email@example.com): In India communal spawning—what we call “mass spawning”—is quite common with monodon. The tank sizes vary from 5-10 metric tons.
The advantage of mass spawning is that the nauplii yields are always higher than those from individual spawning. The disadvantage, it carries the highest risk of pathogen transmission to the entire population even if only one animal in the lot is infected. In the absence of domesticated SPF broodstock for monodon, it’s not a good idea to do communal spawning. In India, for example, WSSV prevalence in wild caught monodon broodstock is as high as 60%. Individual spawning with post-spawning PCR screening would be the best way to go, but the irony is that mass spawning is still the most common practice in India.
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