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Algal Feeds for Shrimp Larvae
November 23, 2007
Todd Blacher (firstname.lastname@example.org): Has anyone ever used Thalassiosira pseudonana for the production of Penaeus vannamei larvae?
John Scarpa (email@example.com): I heard of some work done many years ago by Mary Schilling Clark at Harbor Branch Oceanographic Institution on using Thalassiosira weissflogii, a larger species than T. pseudonana, for P. vannamei larvae culture. There may be an abstract on this somewhere in the World Aquaculture Society archives.
Todd Blacher (firstname.lastname@example.org): I have also used T. weissflogii as a complementary species to Chaetoceros gracilis and/or C. muelleri. My culturing area, however, is very small and the T. weissflogii do not reach high concentrations. I have been culturing T. pseudonana for about four weeks and am getting amazing results (up to 16 million cells per ml), but have not tried to feed them to larvae because I have not cranked up the hatchery yet. Have any of you used T. pseudonana?
Dallas Weaver (email@example.com): Does anyone have experience feeding Spirulina, live or frozen, to penaeid larvae. If yes, to which stages?
John Scarpa (firstname.lastname@example.org): Just remember that cell density is related to cell size. Although weissflogii does not get to the high densities of other species, it does offer a larger chunk (volume, mass), compared to pseudonana. Do you want a dozen White Castle hamburgers or just one Whopper?
Josh Wilkenfeld (email@example.com): Cell size is important, especially during the early zoea stages, and so is the availability of particles for the larvae to encounter, since the early stages of shrimp larvae in particular are continuous filter feeders. Shrimp larvae are not very efficient at digestion and assimilation; they pretty much have to have a constant flow of feed going through their gut to get sufficient energy.
It’s true that weissflogii is one of the most nutritious species of phytoplankton, but its large cell size and relatively low densities in mass culture present two problems: early larval stages have a bit of a problem eating the larger cells and it takes much more floor space to grow them. Also, the cells would have to be concentrated to ensure that the larvae encounter them. Weissflogii usually works best starting at zoea-2 or zoea-3. It’s not a good idea, however, to use weissflogii as the sole, live algae species, at least until the mysis-2 stage, because of the size and availability issues.
I usually start by feeding at about 75-100,000 cells/ml and then add between 2,500-7,500 cells per ml of weissflogii when the larvae reach late Z-2 or Z-3. In the mysis stages, I’ll usually let the muelleri or gracilis densities drop to about 50K/ml, with 5-7.5K/ml weissflogii.
I’ve never worked with pseudonana and can’t say that I know of anyone who has, but that doesn’t mean that it would not be a great species for larval rearing. I tried to find some data on the lipid analyses of various species of diatoms (including weissflogii and pseudonana), but didn’t come up with anything useful during a quick Internet search. I heard a presentation sometime in the early 1980s that gave an analysis of various species of algae, and it was at that point that I decided to adopt the use of weissflogii into my feeding regime because, as I recall, it was second only to Skeletonema costatum in terms of its fatty acid profile. Weissflogii has always been much easier for me to handle in commercial-scale mass culture systems than S. costatum. I love the idea of the small size of pseudonana and the high cell densities, but lacking any definitive information on its food value or comments from anyone who actually has the experience of using this species with shrimp larvae, I guess what you have to do is give it a try. Todd, it would really be great if you ran some comparative trials with muelleri or gracilis.
Regarding Dallas’s question about the use of live or frozen Spirulina in larval feeding, many shrimp hatchery operators, including me, use commercially available dry Spirulina (INVE has a very good product) on a regular basis as a standard feed supplement beginning with zoea-1. I’ve also used Spirulina as a component of a moist maturation pellet that we produce on site. I’ve never tried culturing or feeding live Spirulina, and I’m afraid I’m not a big fan of frozen algae. I believe that the cell quality and nutritional value is diminished in the process of freezing, and you just end up with very dirty tanks and underfed larvae.
Phil Boeing (firstname.lastname@example.org): I concur with all the other postings on this subject and would like to add the following:
Pseudonana is excellent algae for all stages of penaeid larvae. It is most widely cultured for feeding various species of bivalves because it is more of a coldwater species than the higher temperature tolerant weissflogii and the various Chaetoceros species. In some earlier work, weissflogii was used as a complete Artemia replacement for penaeid larvae at the Oceanic Institute. The Thalassiosiras are very high in cholesterol and HUFAs.
Todd Blacher (email@example.com): Thanks. I appreciate your comments. Once I start culturing larvae, if I come up with anything interesting, I’ll share it with all of you.
Samir Kuri (firstname.lastname@example.org): In Belize, I used Spirulina (frozen), pseudonana and weissflogii from zoea 1-2 onward with no muelleri or gracilis. I also used Daphnia with postlarvae and had very good results.
B. Sakthi Mohan Ganesh (email@example.com): On Mafia Island, off Tanzania, I used frozen Spirulina from Z-1 to Z-3 along with supplements and got good performance.
Dallas Weaver (firstname.lastname@example.org): Thanks for the information. I am consulting for a group that hopes to significantly decrease the production cost of Spirulina. Being a much larger algae (50 to 100 µ long), perhaps it could be fed to later stages as a partial Artemia replacement. Frozen Spirulina should be cheaper that Artemia, or any locally produced live algae. I know this market wouldn’t be big, but it could be a fun market. What is your opinion based upon your experience regarding this possible market?
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