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| Larviculture newsletter < Year 2006 < Issue 236 |
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| Larviculture newsletter < Year 2006 < Issue 236 |
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BETTER MANAGEMENT PRACTICES (BMP) MANUAL FOR BLACK TIGER SHRIMP (PENAEUS MONODON)
HATCHERIES IN VIET NAM
Published by NACA, SUMA, THUY SAN-2005, 59 pp.
Contents:
1. Background
2. BMP’s for General Hatchery Management
3. BMP’s for Broodstock Management
4. BMP’s for Larval Rearing Management
Appendix 1: Examples of recording sheets
Appendix 2: Washing/disinfection protocols for shrimp eggs/nauplii
Appendix 3: Decapsulation protocols for Artemia cysts
Appendix 4: Leaflet on how to plan stocking with good quality seed
Background:
The production of black tiger shrimp (Penaeus monodon) seed has been conducted
in Vietnam for nearly 20 years. Currently, there are more than 5,000 hatcheries
throughout Vietnam which produced a total of 26 billion PL in 2004. The two
provinces of Khanh Hoa and Ca Mau are considered the major seed production centres.
To date, hatcheries have been able to supply the demands of the commercial shrimp
farms but variable seed quality, and the prevalence of diseases has resulted
in huge damages to both the hatchery and grow-out sectors.
In order to provide practical and effective technical guidance for shrimp hatchery
management, it is necessary to establish a set of Better Management Practicies
(BMPs) which underpin an effective hatchery production system. These include
the presence of essential infrastructure, the development of the maintenance
of biosecurity, the provision of adequate amounts of clear water, the responsible
use of chemicals, correct feeding practices, and the assurance of the health
status of stocks tbrough in-house and laboratory testing.
This document is not a complete manual on the management of P. monodon hatcheries,
but rather, it concentrates on the implementation of BMPs for the hatchery covering
all of the critical stages and processes in the production cycle, which are
currently believed to be causing problems in Vietnamese hatcheries.
The BMPs have been written for Vietnamese hatchery managers. They should be
given to all personal and a meeting should be held to introduce the protocols
and explain the need for, and contents of the BMPs. This is a good opportunity
to clearly identify and explain any points that generate doubts or that may
be misinterpreted, and to get practical input from the hatchery staff. As new
information becomes available, it will be necessary to update or modify the
BMPs, and any changes must be communicated to all personnel.
(…)
Validation of many of these BMPs has been conducted at 6 pilot hatcheries, 3
in Khanh Hoa and 3 in Ca Mau for the past year under the project “Reducing
risk of aquatic animal disease outbreaks” implemented through a collaboration
of the Ministry of Fisheries, the Danida-funded SUMA (Support to Brackish Water
and Marine Aquaculture) component and the Network of Aquaculture Centres in
Asia-Pacific (NACA) (…).
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NUTRITIONAL VALUE OF BRINE SHRIMP CYSTS AS A FACTITIOUS FOOD FOR ORIUS LAEVIGATUS
(HETEROPTERA: ANTHOCORIDAE)
Patrick De Clercq, Yves Arijs, Thomas Van Meir, Gilbert Van Stappen, Patrick
Sorgeloos, Koen Dewettinck, Marjolaine Rey, Simon Grenier, Gerard Febvay-2005
Biocontrol Science and Technology 15(5): 467-479
Abstract:
Decapsulated cysts of the brine shrimp Artemia franciscana were assessed as a factitious food for rearing the anthocorid predator Orius laevigatus. Developmental and reproductive traits of O. laevigatus reared for a single generation on A. franciscana from three geographical locations or on gamma-irradiated eggs of the Mediterranean flour moth Ephestia kuehniella were compared. There was no effect of diet on nymphal survival but nymphal period on E. kuehniella eggs (12.2 days) was 0.7-1.6 days shorter than on the Artemia diets. The predator developed 0.5-1 day faster on cysts from San Francisco Bay (USA) than on cysts from Great Salt Lake (USA) or Macau (Brazil). Fecundity on brine shrimp cysts from different locations was similar to that on flour moth eggs (142-187 eggs/female). The biochemical composition of decapsulated cysts from San Francisco Bay was compared with that of E. kuehniella eggs. Depending on the type of analysis, Artemia cysts contained higher or similar amounts of protein as compared with E. kuehniella eggs, but amino acid patterns were generally similar. Flour moth eggs were almost three times richer in fatty acids than brine shrimp cysts, with some marked differences in fatty acid profiles. Because nutrient imbalances in a diet may be expressed only after several generations of rearing, the predator was cultured for three consecutive generations on A. franciscana cysts from San Francisco Bay. In the third generation on brine shrimp cysts, nymphs took 18% longer to develop, and adults were shorted-lived and about 60% less fecund than those maintained on E. kuehniella eggs. Brine shrimp cysts may be used as a supplement in the mass production of O. laevigatus but may not be a suitable food for long-term culturing of the predator.
(Laboratory of Agrozoology, Department of Crop Protection, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium, email of P. Declercq: Patrick..Declercq@UGent.be)
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DETERMINATION OF BIOLOGICAL AND PHYSICOCHEMICAL PARAMETERS OF ARTEMIA FRANCISCANA
STRAINS IN HYPERSALINE ENVIRONMENTS FOR AQUACULTURE IN THE COLOMBIAN CARIBBEAN
William N. Camargo, Gabriel C. Durant, Orlando C. Radat, Licet C. Hernandez,
Juan-Carlos G. Linerot, Igor M. Muellet, Patrick Sorgeloos-2005
Saline Systems 1: 9-
Abstract:
Background: Artemia (Crustacea, Anostraca), also known as brine shrimp, are
typical inhabitants of extreme environments. These hypersaline environments
vary considerably in their physicochemical composition, and even their climatic
conditions and elevation. Several thalassohaline (marine) environments along
the Colombian Caribbean coast were surveyed in order to contribute to the knowledge
of brine shrimp biotopes in South America by determining some vital biological
and physicochemical parameters for Anemia survival. Additionally, cyst quality
tests, biometrical and essential fatty acids analysis were performed to evaluate
the economic viability of some of these strains for the aquaculture industry.
Results: In addition to the three locations (Galerazamba, Manaure, and Pozos
Colorados) reported in the literature three decades ago in the Colombian Caribbean,
six new locations were registered (Salina Cero, Kangaru, Tayrona, Bahia Hondita,
Warrego and Pusheo). All habitats sampled showed that chloride was the prevailing
anion, as expected, because of their thalassohaline origin. There were significant
differences In cyst diameter grouping strains in the following manner according
to this parameter: I) San Francisco Bay (SFB-Control, USA), 2) Galerazamba and
Tayrona, 3) Kangarù, 4) Manaure, and 5) Salina Cero and Pozos Colorados.
Chorion thickness values were smaller in Tayrona, followed by Salina Cero, Galerazamba,
Manaure, SFB, Kangarù and Pozos Colorados. There were significant differences
in naupliar size, grouping strains as follows (smallest to largest): I) Galerazamba,
2) Manaure, 3) SFB, Kangarù, and Salina Cero, 4) Pozos Colorados, and
5) Tayrona. Overall, cyst quality analysis conducted on samples from Manaure,
Galerazamba, and Salina Cero revealed that all sites exhibited a relatively
high number of cysts.g-1. Essential fatty acids (EFA) analysis performed on
nauplii from cyst samples from Manaure, Galerazamba, Salina Cero and Tayrona
revealed that cysts from all sites exhibited high arachidonic acid:20:4(n-6)
(ArA) and eicosapentaenoic acid: 20:5(n-3) (EPA) levels comparable to the control
sample (SFB). In contrast, most cysts collected (including SFB) at different
locations, and during different months, presented low docosahexaenoic acid:
22:6(n-3) (DHA) levels (Manaure was the only exception with high DHA levels).
Some variations in EPA and ArA levels were observed in all sites, contrasting
with the much lower DHA levels which remained constant for all locations, except
for Manaure which exhibited variable DHA levels. DHA/EPA ratio was overall very
low for all sites compared to SFB cysts. All strains had a low DHA/ArA, but
a high EPA/ArA ratio, including the control.
Conclusion: The Colombian A. franciscana habitats analyzed were determined to
be thalassohaline, and suitable for A. franciscana development. EFA profiles
demonstrated that Tayrona, Galerazamba, Manaure and Salina Cero strains are
suitable food for marine fish and crustacean culture because of their high EPA/ArA
ratio, but might have to be fortified with DHA rich emulsions depending on the
nutritional requirements of the species to be cultured, because of their overall
low DHA content. The relatively small nauplii are appropriate for marine larvae
culture. In contrast, the strains from Tayrona, Kangarù, Salina Cero,
and Pozos Colorados may be of use but limited to Artemia small biomass production
quantities, because of the small surface area of their respective locations;
Artemia could be exploited at these locations for local aquaculture applications.
In general, cyst quality evaluation for Manaure, Salina Cero and Galerazamba
cysts revealed that cysts from these three locations could improve their quality
by concentrating efforts on cyst processing techniques. Finally, most locations
had great A. franciscana production potential and require different degrees
of water quality and/or infrastructure management.
(Fisheries and Illinois Aquaculture Center, Southern Illinois University Carbondale, Carbondale, IL 62901, USA, email of W. Camargo: wcamargo@excite.com)
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DIET AND WEANING AGE AFFECT THE GROWTH AND CONDITION OF DOVER SOLE (SOLEA SOLEA
L.)
Rebeca A. Rueda-Jasso, Luis E.C. Conceicao, Wim De Coen, Jean Francois Rees,
Patrick Sorgeloos-2005
Ciencias Marinas 31(7): 477-489
Abstract:
The effect of diet type (frozen Artemia biomass and two inert diets: micro-bound [MB] and micro-extruded [ME]) and two weaning ages (early weaning and late weaning, 50 and 64 days after hatching, respectively) were studied in Solea solea larvae. The experiment lasted 56 and 42 days for early and late weaning, respectively. The mortality results showed the highest values for late weaning (39%) in the Artemia treatment. No significant differences in mortality were observed between the inert diets. The final dry weight values were higher for late weaning than for early weaning. At both weaning ages, fish receiving the same treatments had similar tendencies for dry weight and standard length. Fish fed with MB presented significantly higher dry weight and standard length, followed by ME, while the lowest values at both weaning ages were recorded for the Artemia treatment. Similar amounts of highly unsaturated fatty acid fractions among the inert diets were reflected by the absence of significant differences in the susceptibility to oxidation (thiobarbituric acid reactive substances testing); however, significant differences were found in carbohydrate, protein and lipid contents of whole-body homogenates for both early and late weaning. At the end of the experiment no significant differences in biochemical contents were observed between the two inert diets. The results of this study suggest that weaning starting on day 50 (early weaning), using a good quality inert diet, leads to higher survival, growth and fish condition.
(Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Rozier 44, B9000 Gent, Belgium; email of R. Rueda-Jasso: Rebeca_Aneli@yahoo.com)
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THE IMPACT OF MUTATIONS IN THE QUORUM SENSING SYSTEMS OF AEROMONAS HYDROPHILA,
VIBRIO ANGUILLARUM AND VIBRIO HARVEYI ON THEIR VIRULENCE TOWARDS GNOTOBIOTICALLY
CULTURED ARTEMIA FRANCISCANA
Tom Defoirdt, Peter Bossier, Patrick Sorgeloos, Willy Verstraete-2005
Environmental Microbiology 7(8): 1239-1247
Abstract:
Disruption of quorum sensing, bacterial cell-to-cell communication by means of small signal molecules, has been suggested as a new anti-infective strategy for aquaculture. However, data about the impact of quorum sensing on the virulence of aquatic patho¬gens are scarce. In this study, a model system using gnotobiotically cultured Artemia franciscana was developed in order to determine the impact of muta¬tions in the quorum sensing systems of Aeromonas hydrophila, Vibrio anguillarum and V. harveyi on their virulence. Mutations in the autoinducer 2 (AI-2) syn¬thase gene luxS, the AI-2 receptor gene /uxP or the response regulator gene luxO of the dual channel quorum sensing system of V harveyi abolished viru¬lence of the strain towards Artemia. Moreover, the addition of an exogenous source of AI-2 could restore the virulence of an AI-2 non-producing mutant. In con¬trast, none of the mutations in either the acylated homoserine lactone (AHL)-mediated component of the V harveyi system or the quorum sensing systems of Ae. hydrophila and V anguillarum had an impact on virulence of these bacteria towards Artemia. Our results indicate that disruption of quorum sensing could be a good alternative strategy to combat infec¬tions caused by V harveyi.
(Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium; email of W. Verstraete: willy.verstraete@UGent.be)
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OPTIMUM TIME FOR WEANING SOUTH AFRICAN SCYLLA SERRATA. (FORSKAL) LARVAE FROM
ROTIFERS TO ARTEMIA
J.A. Davis, M. Wille, T. Hecht, P. Sorgeloos-2005
Abstract:
To determine the optimum time at which to wean Scylla serrata larvae from rotifers onto Anemia two experiments were conducted, approximately 1 month apart, using larvae from two different female crabs. In the first experiment, the larvae in three treatment groups, with nine replicates each, were fed rotifers for the first 8 days after hatching. Artemia were. introduced on days after hatch (DAH) 0 - during the first zoeal instar (treatment R + A); on DAH 4 - during the second zoeal instar (treatment R4A); on DAH 8 - during the third zoeal instar (treatment R8A). In a control (ROT) larvae were fed with rotifers exclusively for 18 days until the completion of metamorphosis to megalopa. In the second experiment, the same four feeding schedules as in experiment 1 were used with an additional group of larvae (treatment AC) that were fed only on Artemia throughout the rearing period. Similar results were recorded in the two experiments. Larvae in treatments R + A and R4A performed significantly better than those in treatments R8A, ROT and AC. This was particularly evident when examining the proportion of zoeae which successfully completed metamorphosis to megalopa. Poor performance of larvae in treatments AC and ROT implied that rotifers are needed as a first food, but that rotifers alone do not fill the nutritional requirements of S. serrata larvae. Poor performance of larvae in treatment R8A sug¬gested that the diet should be supplemented with Artemia before the end of the zoea 3 stage.
(Laboratory of Aquaculture & Artemia Reference Center, Gent University, Gent, Belgium; email of J. Davis: jeromed@iafrica.com)
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BACTERIA ASSOCIATED WITH EARLY LIFE STAGES OF THE GREAT SCALLOP, PECTEN MAXIMUS:
IMPACT ON LARVAL SURVIVAL
Lise Torkildsen, Christophe Lambert, Are Nylund, Thorolf Magnesen, Øivind
Bergh-2005
Aquaculture International 13(6): 575 - 592
Abstract:
A bacteriological study was carried out at a scallop (Pecten maximus) hatchery near Bergen, western Norway following a severe increase in mortality rates during the larval stages of the scallops. No larvae survived to settling, except for those in groups treated prophylactically with chloramphenicol. In order to identify pathogenic strains of bacteria, we performed a challenge test on 10- to 16-day-old larvae using isolated bacterial strains from the hatchery. Infection with six of these strains produced mortalities that were not statistically different from that resulting from infection with the known pathogen Vibrio pectenicida. However, about 5% of the strains tested in the challenge experiment produced higher motility rates than found in the unchallenged control group, indicating a possible probiotic effect. On the basis of 16S rDNA analysis on these strains, the phylogenetic tree indicated two groups of apparent pathogens: (1) one strain, LT13, grouped together with Alteromonas/Pseudoalteromonas; (2) a cluster of strains grouped together with Vibrio splendidus (LT06, LT21, LT73, PMV18 and PMV19). Strain LT13 was isolated from cultures of the microalga Chaetoceros calcitrans used for feed, while the other strains were isolated from larval cultures. Transmission electron microscopy showed intracellular bacteria that resembled bacteria in the groups Chlamydiaceae and Rickettsiaceae.
(Institute of Marine Research, P.O. Box 1870 Nordnes, N-5817 Bergen, Norway; email of Øivind Bergh: oivind.bergh@imr.no)
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A SYSTEM FOR MODEL-BASED BIOMASS ESTIMATION OF LARVAE IN INTENSIVE COD LARVICULTURES
Morten O. Alver, Jo A. Alfredsen, Gunvor Øie-2005
Aquaculture International 13(6): 519 - 541
Abstract :
High and unpredictable mortality rates are observed in the larval rearing of cod (Gadus morhua). As a means of addressing this problem, we present a model-based estimator system which can be used to indirectly measure the larval density through monitoring the live food dynamics and larval growth. The estimator has been evaluated in a conceptual context using a preliminary model formulation, and the observability of the process has been investigated. It was found that the two parameters, live food dynamics and larval growth, contain enough information for the larval density to be estimated under noisy conditions, given the correct model. When the system is applied practically, the estimation error will depend on the measurement and model accuracy; this is especially true with respect to the predictability of the feed intake rate of the fish.
(Department of Engineering Cybernetics, Norwegian University of Science and Technology, O.S. Bragstads plass 2D, 7491 Trondheim, Norway; email of M. Alver: alver@itk.ntnu.no)
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EVALUATION OF FATTY ACID ENRICHMENT OF LIVE FOOD FOR YELLOWTAIL SNAPPER OCYURUS
CHRYSURUS LARVAE
Faulk, C.K., Holt, G.J., Davis, D.A.-2005
J. World Aquacult. Soc. 36 (3): 271-281
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INVESTIGATION OF FRESH AND FREEZE-DRIED SEABREAM SPARUS AURATA L. EGGS AS A
FATTY ACID SOURCE IN THE ENRICHMENT OF BRACHIONUS SP.: POTENTIAL USE OF A WASTE
PRODUCT
Morais, S., Narciso, L., Dores, E. et al.-2005
J. World Aquacult. Soc. 36 (3): 302-310
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DUAL BENEFITS OF WHEY PROTEIN CONCENTRATE IN A MICROENCAPSULATED DIET FOR LARVAL
WHITE SHRIMP, LITOPENAEUS VANNAMEI
Medina-Reyna, C.E., Ronson-Paulin, J.A., Hernandez-Rojas, F. et al.-2005
J. World Aquacult. Soc. 36 (3): 401-410
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FORAGING AND GROWTH OF HATCHERY-REARED HONMASU SALMON PARR IN A NATURAL RIVER
Munakata, A., Amano, M.; Kitamura, S. et al.-2005
J. World Aquacult. Soc. 36 (3): 411-415
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EFFECTS OF POTASSIUM, MAGNESIUM AND AGE ON GROWTH AND SURVIVAL OF LITOPENAEUS
VANNAMEI POST-LARVAE REARED IN INLAND LOW SALINITY WELL WATERS IN WEST ALABAMA
Davis, D.A., Boyd, C.E., Rouse, D.B. et al.-2005
J. World Aquacult. Soc. 36 (3): 416-419
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PATHOGENIC BACTERIA ISOLATED FROM DISEASE OUTBREAKS IN SHELLFISH HATCHERIES.
FIRST DESCRIPTION OF VIBRIO NEPTUNIUS AS AN OYSTER PATHOGEN
Susana Prado, Jesús L. Romalde, Jaime Montes, Juan L. Barja-2005
Diseases of Aquatic Organisms 67(3): 209-215
Abstract:
Shellfish hatcheries are often affected by disease outbreaks. Three such episodes were investigated in different Galician hatcheries in order to establish the relationship between present microbiota and mortalities. Isolates were obtained from various parts of the hatcheries. Experimental tests for pathogenicity were carried out in microscale experiments using selected strains on Ostrea edulis larvae. The pathogenicity of 1 strain from each outbreak was demonstrated and shown to cause high mortalities (ranging from 98.5 to 100%) ijn 72 to 96 h after inoculation of larval cultures. All 3 strains belong to the genus Vibrio. One of the strains was identified as Vibrio neptunius and is the first description of this species as a molluscan pathogen. The other 2 strains showed low similarity with the Vibrio species analysed and may constitute new species within this genus.
(Departamento de Microbiologia y Parasitologia, Facultad de Biologia, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain; email of S. Prado: sprado@usc.es)
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GENETIC STRUCTURE AND GENETIC RELATEDNESS OF A HATCHERY STOCK OF SENEGAL SOLE
(SOLEA SENEGALENSIS) INFERRED BY MICROSATELLITES
Javier Porta, J. Maria Porta, Gonzalo Martínez-Rodríguez, M. Carmen
Alvarez-2005
Aquaculture 251(1): 46-55
Abstract:
Solea senegalensis is a fish species in an early stage of domestication. A
commercial hatchery in southern Spain experienced a dramatic failure in spawning
and embryo survival, after incorporation into the broodstock of fish reared
in their hatchery. To assess the impact of management on the stock quality,
a population genetics study was made of adult broodstock present at this hatchery
in 2000. The broodstock was composed of a group of fish of wild origin and two
more groups from F1 progeny. A set of eight microsatellite loci was used to
compare genetic variability among the three groups and to establish the relationships
between pairs of individuals within each group.
Individuals from F1 origin showed a substantial reduction in genetic variability
when compared to those from the wild. There was a greater than 50% decrease
in the number of alleles per locus corrected by sample size and 16% and 26%
reductions in He values in the two F1 groups, respectively. The degree of genetic
relationship between individuals, evaluated by the relatedness estimator, rxy,
and by graphical approaches, revealed a high proportion, almost 75%, of full-sibs
and half-sibs in both F1 groups, which might account for the reduction in overall
variability. The high proportion of siblings also suggests a reproductive pattern
in this stock in which few individuals breed successfully. This mating behaviour,
along with factors inherent to selection and management systems, might be responsible
for the negative effects on the reproductive capacity of the stock.
(University of Málaga, Faculty of Sciences, Dept. of Genetics, Campus de Teatinos, 29071 Málaga, Spain; email of M. Alvarez: alvarez@uma.es)
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AN INSULIN-LIKE SYSTEM INVOLVED IN THE CONTROL OF PACIFIC OYSTER CRASSOSTREA
GIGAS REPRODUCTION: HRIGF-1 EFFECT ON GERMINAL CELL PROLIFERATION AND MATURATION
ASSOCIATED WITH EXPRESSION OF AN HOMOLOGOUS INSULIN RECEPTOR-RELATED RECEPTOR
L. Gricourt, M. Mathieu , K. Kellner-2005
Aquaculture 251(1): 85-98
Abstract:
The putative involvement of insulin-like peptides in the control of the reproduction of the Pacific oyster Crassostrea gigas was investigated using different approaches. In conjunction with a monthly histological analysis of the oyster reproductive cycle, in vitro biological effects of the human recombinant IGF-1 (hrIGF-1) on dissociated germinal cells were mesured over 1 year using [3H]-thymidine and [14C]-amino acid mixture as tracers for DNA and protein synthesis. DNA synthesis was stimulated by hrIGF-1 in November (114 ± 11% for 10- 7M), December (46 ± 6% for 10- 7 M) and January, which was identified as the highest gonial mitosis period. A clear dose–effect was observed in January with a maximum activation of 68 ± 7% for 10- 12 M. Germinal cell protein synthesis was also stimulated in March (20 ± 1% for 10- 10 M), April (41 ± 5% for 10- 13 M), May (25 ± 4% for 10- 13 M), and by almost all of hrIGF-1 doses in June (21.5 ± 2% for 10- 13 M) and July (34 ± 1% for 10- 13 M). This suggests the involvement of insulin-like substances in gonadal tubule rebuilding (December), as well as in the development of germinal cells (March, April), and in the summer maturation of gametes (May, June, July). These insulin-like effects conform with the expression pattern of the recently identified C. gigas insulin receptor-related receptor (CIR): It appeared highly expressed in the gonadal area during gonial mitosis phase, but also in maturating oocytes, suggesting the involvement of an insulin-like system in gonial proliferation and maturation. Moreover, CIR showed differential expression during embryogenesis and larval developmental stages. The expression of maternal CIR during the embryonic and early larval development, followed by the increasing zygotic CIR expression from D larvae to 11-day-old veliger larvae, then a decrease until metamorphosis, also suggest that insulin-like peptide is involved in organogenesis.
(Laboratoire de Biologie et Biotechnologies Marines, EA 962, UMR IFREMER Physiologie et Ecophysiologie des Mollusques Marins (PE2M), Université de Caen Basse-Normandie, 14032 Caen cedex, France ; email of L. Gricourt : l.gricourt@ifrance.com)
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GROWTH AND GONADAL DEVELOPMENT IN DIPLOID AND TRIPLOID TURBOT (SCOPHTHALMUS
MAXIMUS)
R.M. Cal, S. Vidal, C. Gómez, B. Álvarez-Blázquez, P. Martínez,
F. Piferrer-2005
Aquaculture 251(1) : 99-108
Abstract:
This study determined the effect of triploidy on the survival, growth and gonadal development of turbot from 6 to 48 months of age. From 6 to 24 months of age (first sexual maturity), survival was similar in both ploidies (P > 0.05). From 24 to 48 months of age, after the first sexual maturity, survival was 91.9% in diploids and 100% in triploids, which did not exhibit the post-spawning-associated mortality. Growth was similar for both ploidies during the first year of life. After that, triploids grew significantly (P < 0.05) more that diploids, with more marked differences after each spawning season. From 24 to 48 months, the average weight difference between both ploidies was 11.4 ± 1.9%, ranging from 4.3 to 23.0%. At 47 months of age, the biomass of triploids was 10.3% greater in total weight and 14.3% greater in eviscerated weight. Gonads of triploid males were similar to that of diploids, whereas in triploid females, they were significantly smaller and rudimentary. A histological analysis carried out at 47 months of age showed complete sterility of triploids in both sexes. Sex ratio was 1 male (M):0.6 female (F), for diploids, significantly (P < 0.05) different from 1:1, and 1 M:3.3 F for triploids, significantly (P < 0.05) different from 1:1 and from the diploids. Since females grow more than males, culture of triploids benefited from the high female ratio, which helped to reduce size dispersion. In addition, their sterility allowed better performance by avoiding the reduction in growth that takes place during the spawning periods. Together, these observations indicate that triploidy induction can be an interesting option for turbot aquaculture, especially for the production of large-size fish of more than 2 years of age.
(Instituto Español de Oceanografía (IEO), Centro Costero de Vigo, Vigo, Cabo Estay-Canido, Apartado 1552, 36280-Vigo, Spain; email of R. Cal: rosa.cal@vi.ieo.es)
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THE IMPACT OF LIGHT INTENSITY AND ALGAL-INDUCED TURBIDITY ON FIRST-FEEDING
SERIOLA LALANDI LARVAE
Alexander G. Carton-2005
Aquaculture Research 36(16): 1588 -
Abstract:
Feeding performance (intensity and incidence) of first-feeding yellowtail kingfish larvae was evaluated under a range of light intensities and algal-induced turbidities. Larvae were fed with varying degrees of success under all light intensities tested (0–17 µmol s1 m2), in both clearwater and greenwater (8 × 104 cells mL1). There was a consistent trend for feeding performance to increase with larval age and light intensity in both clearwater and greenwater conditions, demonstrating that visual proficiency increases with larval age. Feeding intensity remained low over the first 3 days of first feeding across all light intensities tested. Days 6 and 7 post-hatch larvae showed considerably higher feeding intensities particularly at 8 and 17 µmol s1 m2. This improvement indicates an ontogenetic shift in sensory or locomotor competence. First-feeding larvae performed equally well in both clearwater and greenwater (8 × 104 cells mL1) conditions, although at the lowest light intensity tested (0.1 µmol s1 m2) feeding performance was noticeably reduced. Feeding performance was severely diminished across all larval ages at an algal cell density of 32 × 104 cells mL1, demonstrating that for this species algal-induced turbidities >16 × 104 cells mL1 adversely affect the ability to capture free-swimming prey during the first-feeding window.
(Leigh Marine Laboratory, PO Box 349, Warkworth 1241, New Zealand; email of A. Carton: a.carton@auckland.ac.nz)
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GROWTH OF EARLY JUVENILE WINTER FLOUNDER (PSEUDOPLEURONECTES AMERICANUS WALBAUM)
Benjamin de Montgolfier, Céline Audet, Yvan Lambert-2005
Aquaculture Research 36(16) : 1595-
Abstract:
Metamorphosis is a critical developmental stage in marine fish species, but mortalities are also elevated at the settling phase. Our objective was to evaluate the effects of different rearing systems and larval diets on survival, general condition and pigmentation of newly settled winter flounder (Pseudopleuronectes americanus) juveniles. At settlement, winter flounder juveniles were reared in two different types of tanks (plankton kreisel and rectangular raceway). The early juveniles were followed for 1 month and their condition was evaluated using biochemical indices. Juveniles did not show signs of fin rot and pigmentation was well developed, but they had different RNA/DNA ratios. This study highlights the fact that rearing conditions at the onset of the juvenile stage may be critical for successful juvenile production.
(Institut des sciences de la mer de Rimouski (ISMER), Université du Québec à Rimouski 310 allée des Ursulines, C.P. 3300, Rimouski, QC, Canada, G5L 3A1 ; email of C. Audet : celine_audet@uqar.qc.ca)
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ANTIMICROBIAL ACTIVITY IN BACTERIA ISOLATED FROM SENEGALESE SOLE, SOLEA SENEGALENSIS,
FED WITH NATURAL PREY
Pavlos Makridis, Silvia Martins, Matina Tsalavouta, Lidia Catalão Dionisio,
Giorgos Kotoulas, Antonis Magoulas, Maria Teresa Dinis-2005
Aquaculture Research 36(16): 1619 -
Abstract:
Intestinal bacteria in marine fish may produce antimicrobial substances which
inhibit pathogenic bacteria. The aim of this study was to determine the influence
of a change of fish diet on the antimicrobial activity of the culturable aerobic
gut microflora of Senegalese sole, Solea senegalensis. Pre-adult 15-month-old
fish previously fed on an artificial diet, were fed polychaetes (Hediste diversicolor),
which form part of the natural diet of Senegalese sole. Samples were taken0,
3 and 6 weeks after start of the experiment from the stomach, small and large
intestine of the fish. The bacterial strains isolated from these samples were
sub-cultured to pure cultures and stored at -80°C. Several biochemical tests
were run to obtain some basic phenotypic characteristics of the isolated strains.
Amplification and sequencing of 16S rDNA fragments were used to identify the
majority of the bacterial strains isolated. The identification by use of this
molecular approach gave results in agreement to the phenotypic characterization.
Feeding with polychaetes significantly increased (P<0.05) the numbers of
presumptive Vibrio isolates in the gut. The number of bacterial strains with
antimicrobial activity, as determined by two in vitro approaches, was significantly
(P<0.05) increased by feeding with polychaetes.
Affiliations
(Hellenic Center for Marine Research, PO Box 2214, GR 71003, Heraklion, Crete, Greece; email of P. Makridis: makridis@her.hcmr.gr)
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EFFECTS OF SINGLE AND COMBINED MICROALGAE ON LARVAL GROWTH, DEVELOPMENT AND
SURVIVAL OF THE COMMERCIAL SEA CUCUMBER HOLOTHURIA SPINIFERA THEEL
P S Asha, P Muthiah-2006
Aquaculture Research 37(2): 113 -
Abstract:
The results of the study on the suitable algal feed for the mass rearing of holothurian larvae through hatchery system are presented. Auricularia larvae, after 48 h of fertilization, obtained from induced spawning of Holothuria spinifera, were fed with different algae Isochrysis galbana, Nanochloropsis salina, Pavlova lutheri, Tetraselmis chuii and Chaetoceros calcitrans as well as I. galbana+C. calcitrans to ascertain the effect of single and combined microalgal diet. The rate of feeding was 2 × 104 cells larvae1 day1 for a period of 9–12 days. The growth rate of 59 µm day1 with 90% and 43 µm day1 with 100% occurrence of late auricularia in the larvae fed with C. calcitrans alone and I. galbana+C. calcitrans, respectively, indicated that C.calcitrans itself or in combination with I. galbana is the effective feed for the larvae of H. spinifera.
(Tuticorin Research Centre of Central Marine Fisheries Research Institute, South Beach Road Extension, Karapad, Tuticorin 628 001, Tamil Nadu, India.; email of P.Asha: ashasanil@yahoo.com)
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A NEW APPROACH TO KELP MARICULTURE IN CHILE: PRODUCTION OF FREE-FLOATING SPOROPHYTE
SEEDLINGS FROM GAMETOPHYTE CULTURES OF LESSONIA TRABECULATA AND MACROCYSTIS
PYRIFERA
Renato Westermeier, David Patiño, Maria Ines Piel, Ingo Maier, Dieter
G Mueller-2006
Aquaculture Research 37(2): 164 -
Abstract:
Substantial amounts of Macrocystis and Lessonia are traditionally harvested and exported from Chile as raw material for alginate. Because of intense mariculture of abalone (Haliotis ssp.), herbivorous molluscs that feed on brown kelps, pressure on local populations of Macrocystis and Lessonia has increased to critical levels within the past 5 years, strongly supporting efforts to produce algae maricultured biomass. Here, we present our results on the development of new techniques for large-scale kelp mariculture in Chile. We have abandoned the traditional technique of direct spore seeding onto inoculation lines. Instead, we used gametophyte cultures that were manipulated to enter gametogenesis and to produce synchronous batches of 104–105 embryos. Juvenile sporophytes were cultured under permanent aeration and agitation, floating unattached in contamination-free glass bottles up to 10 L, plexiglass cylinders and 800 L greenhouse tanks. When holdfast initials were formed at a size of 8 cm, the sporophytes were spliced into Nylon rope fragments and transferred to the sea. Twelve months after initiation of gametogenesis in the laboratory, Macrocystis pyrifera attained 14 m length and 80 kg fresh weight m1 line in the sea. For Lessonia trabeculata 6 months after gametogenesis initiation, 0.25 kg fresh weight m1 was attained in the sea.
(Facultad de Pesquerias y Oceanografía, Universidad Austral de Chile, Campus Puerto Montt, Casilla 1327, Puerto Montt, Chile; email of R. Westermeier: rwesterm@uach.cl)
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