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| Larviculture newsletter < Year 2005 < Issue 220 |
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| Larviculture newsletter < Year 2005 < Issue 220 |
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ANNOUNCEMENT: 9 th Conference of the International Society for Salt Lake Research (ISSLR): 26-30 September 2005, Perth, Western Australia
For information, contact:
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BOOK OF INTEREST:
THE SUITABILITY OF THE FREE-LIVING NEMATODE PANAGRELLUSREDIVIVUS AS ALTERNATIVE LIVE FOOD FOR FIRST FEEDING FISH LARVAE
By Christian Schlechtriem
Abstract:
Although hobby aquarists have claimed for decades that free-living nematodes are a potential food source for first feeding fish, their use has not become a real alternative to other common live foods, due to the lack of suitable mass production technologies. A new technology for mass production of Panagrellusredivivus enables hatchery operators to rely on a cheap, standardized and permanently available live food for first feeding fish larvae. The technology involves the multiplication of nematodes in monoxenic (single micro-organism: Saccharomycescerevisiae) solid culture in autoclavable plastic bags. Different culture media have been tested and found to induce consistently high production rates. Yields of about 400 million nematodes per kg medium have been/can be reached.
Mass produced nematodes were tested on common carp (Cyprinuscarpio) and whitefish (Coregonuslavaretus) larvae, which differ in size and the morphology of their alimentary canal. These studies indicated that P. redivivus is readily ingested by first feeding fish larvae. Different stages of nematode digestion could be observed in transverse sections of fish larvae sampled at regular intervals after feeding. By means of a stable isotope approach the onset of nutrient retention as well as the subsequent assimilation of carbon from the nematodes could be determined precisely for first feeding common carp and whitefish larvae. Larvae fed nematodes showed a high survival rate and could afterwards easily be adapted to a commercial dry diet, after, for example, one week of feeding.
The fatty acid composition of P. redivivus can be enhanced by enriching the culture medium with essential fatty acids. In this way the nutritional value of mass produced nematodes can be specifically tailored to the particular needs of fish larvae. Due to its small size (length: 50-2000 µm) and round, enlongated shape, as well as the availability to survive for up to 72 hours in sea water, P. redivivus has a high potential as live food organism for small-smouthed marine fish larvae.
This book gives an overview of current results which prove the suitability of P. redivivus as alternative live food for first feeding fish larvae. Directions for future research are described.
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JOURNAL OF SHELLFISH RESEARCH
Vol. 23, No. 4, December 2004
CONTENTS:
Proceedings 5th International Symposium on Abalone Biology, Fisheries, and Culture: SELECTED TITLES
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A highly efficient oyster spat collector made with recycled materials
Esperanza Buitrago, Daniela Alvarado-2005
Aquacultural Engineering, 33 (1): 63-72
Abstract:
This study presents data from over 7 years on the numbers of spat settling onto plastic bottles (2 l soda bottles). The bottles were cut longitudinally into two halves and suspended in a series from 0.10 to 2.00 m in depth in the “Laguna de la Restinga” on Margarita Island, Venezuela. The surface area of one entire collector was 1.8 m2 (formed by 20 bottles halves) and the average number of oysters attaching after a deployment period of 1 month was 326 spat/m2 (and the monthly average ranged from 42 to 1496 over 7 years). Plastic bottles used in this way provided an efficient and cost-effective means of collecting oyster spat, and the spats were easily detached because of the flexibility of the plastic surfaces.
(Departamento de Cultivos, Estación de Investigaciones Marinas de Margarita, Fundación La Salle de Ciencias Naturales, EDIMAR/FLASA, Punta de Piedras 6318, Isla de Margarita, Venezuela ; email of E. Buitrago: esperanzabuitrago_2004@hotmail.com)
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The effect of sea bream (Sparus aurata) broodstock and larval vaccination on the susceptibility by Photobacterium damsela subsp. piscicida and on the humoral immune parameters
A. Hanifa, V. Bakopoulos, I. Leonardos, G.J. Dimitriadis-2005
Fish & Shellfish Immunology, 19 (4): 345-361
Abstract:
Sea bream broodstock were immunised 1 or 2 months before spawning with a novel photobacteriosis vaccine. Sixty-seven-day-old larvae (mean weight 22.3 mg) originating from immunised and non-immunised parents were experimentally infected with the Photobacterium damsela subsp. piscicida (Phdp). Larvae from immunised fish showed delayed onset and lower mortality (66.67%) compared with larvae from control fish (80%). Eighty-nine-day-old larvae (mean weight 162.2 mg) from both groups were bath vaccinated with Phdp and Escherichia coli lipopolysaccharides (LPS) and larval samples were collected for measurement of humoral parameters. Larvae vaccinated with Phdp and LPS showed significantly higher anti-protease activity, lysozyme activity and total immunoglobulin compared to the controls. One-hundred-and-twenty-day-old larvae (mean weight 297.85 mg) from both parental groups were challenged with (LD70) virulent Phdp bacterial cells. Vaccinated larvae from both groups showed significantly less mortality compared to the respective controls. The RPS values of larvae from immunised parents vaccinated with Phdp and LPS was 95.83% and 72.22%, respectively. The RPS values of larvae from non-immunised parents vaccinated with Phdp and LPS was 62.5% and 70.83%, respectively. Results are discussed with respect to the beneficial effect of broodstock immunisation prior to spawning and the immunisation of larvae on their survival against photobacteriosis.
(Division of Genetics, Department of Biology, University of Patras, Patras 26500, Greece; email of G. Dimitriadis: dimigeor@upatras.gr)
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