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SURFACE DISINFECTION OF COD GADUS MORHUA AND HADDOCK MELANOGRAMMUS AEGLEFINUS
EGGS WITH BRONOPOL
James W. Treasurer, Eileen Cochrane, Andrew Grant-2005
Aquaculture 250 (1-2): 7-35
Abstract:
Using current practice of immersion, the survival of cod eggs disinfected with 50 mg l- 1 to 500 mg l- 1 bronopol (as Pyceze [50%W/V bronopol], Novartis Animal Vaccines Ltd.) for 45 s, was higher (83–89%) when compared with negative controls (48%). Hatching larvae survived exposure to Pyceze but not to Kickstart (25% peracetic acid/hydrogen peroxide, CIDLines UK), a common disinfectant in United Kingdom marine finfish hatcheries. Bacterial numbers on cod eggs were 30 CFU ml- 1 following contact with 50 mg l- 1 bronopol and zero at 1000 mg l- 1 compared with 14,000 CFU ml- 1 with no disinfection. Although survival to hatch of haddock eggs in 50 mg- 1 bronopol (71.6%) was higher than in non-disinfected eggs (62.4%) this was not significant. Haddock eggs required a concentration of 500 mg l- 1 bronopol to achieve a significant reduction in bacterial numbers, 352 cf. 1546 CFU ml- 1 in seawater controls. Alternative techniques to immersion were assessed to reduce repeated handling and possible damage to eggs. A flow-through system utilising a peristaltic dosing pump was ineffective in achieving the target concentration of Pyceze and contact time, but use of a static immersion technique in an incubation unit, with 30 min daily exposure to 50 mg l- 1 bronopol, gave 63% survival to hatch compared with 35% with a negative control. Bacterial numbers of 892 CFU ml- 1 following treatment with Pyceze were significantly lower than the 91,400 CFU ml- 1 in negative controls. In target animal safety studies with 250 mg l- 1 bronopol, namely × 5 target concentration for 2× exposure time, survival of haddock eggs of 88.7% was significantly higher when compared with 53.1% in non-disinfected.
Scottish Association for Marine Science Ardtoe
Ardtoe Marine Laboratory
Acharacle
Argyll PH36 4LD
UK
email of J. Treasurer: jim.treasurer@sams.ac.uk
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EVALUATION OF THREE STRATEGIES USING DNA MARKERS FOR TRACEABILITY
IN AQUACULTURE SPECIES
Ben Hayes, Anna K. Sonesson, Bjarne Gjerde-2005
Aquaculture 250 (1-2): 70-81
Abstract:
Traceability schemes for aquaculture species are essential for tracing market
product to farm of origin in the event of detection of disease or toxins in
the market fish. DNA markers have been proposed as a tool for traceability.
These markers can be used to genotype fish by taking a sample from live fish
or fish product at any stage along the production chain. In this paper, we consider
three alternate traceability schemes using DNA markers. The example of the Norwegian
farmed Atlantic salmon industry was used. This industry, like many aquaculture
industries, has three tiers, the nucleus, multiplier and commercial tiers. The
nucleus individuals are grandparents of the commercial fish, and the multiplier
individuals are the parents of the commercial fish. The traceability strategies
we considered were: (1) FS, assignment of market place fish to full sib families
based on the marker information (this strategy assumes all individuals from
a full sib family are allocated to a single farm and a limited number of fish,
representing all full sib families on that farm, are genotyped); (2) PAR, assignment
of market place fish to parents (multiplier individuals) and (3) GRAND, assignment
of market place fish to grandparents (nucleus individuals). Using simulation,
we determined the number of DNA markers required to achieve 95% of correct assignment
decisions for each strategy. The simulation included a wild population which
contributed to market place fish. The wild fish were correctly assigned if they
were excluded from belonging to the farmed population in each strategy, otherwise
they were incorrectly assigned. Both microsatellite markers or single nucleotide
polymorphism markers were considered. Seventy five, 15, and 50 microsatellites
were required to achieve 95% correct assignment decisions for FS, PAR and GRAND,
respectively. Four hundred, 75 and 200 SNPs were required to achieve 95% correct
assignment decisions for FS, PAR and GRAND, respectively. If the cost of genotyping
microsatellites is assumed to be five times as high as genotyping a SNP, GRAND
using SNP markers is the cheapest strategy. The logistics of implementing each
strategy are discussed. GRAND in particular and PAR in some industries requires
complicated logistics. The most suitable and cost effective traceability strategy
for a particular industry will depend heavily on the organisation of that industry,
for example the degree of recording transfer of fish, eggs and larvae between
tiers. Even if complicated logistics prevent the adoption of marker based schemes
by some industries, traceability with DNA markers may still be important for
verification of labelling-based schemes.
AKVAFORSK,
Institute for Aquaculture Research,
P.O. 5010,
1432 Ås,
Norway; e
email of Ben Hayes: ben.hayes@akvaforsk.no
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HERITABILITY OF THE CATEGORICAL TRAIT ‘NUMBER OF SPAWNS’
IN PACIFIC WHITE FEMALE SHRIMP PENAEUS (LITOPENAEUS) VANNAMEI
Ana M. Ibarra, Fabiola G. Arcos, Thomas R. Famula, Elena Palacios, Ilie S. Racotta-2005
Aquaculture 250 (1-2): 95-101
Abstract:
We estimated the heritability for the number of spawns during a reproductive
period of 30 days in female Pacific white shrimp, Penaeus (Litopenaeus) vannamei.
The estimate was based on Bayesian statistical methods, with data collected
on full-sibs and mothers and daughters during two generations (years). Heritability
was estimated in a threshold model for categorical data, including the fixed
effects of year and sets within years. All ablated females provided information
regardless of whether they spawned or not. Phenotypes were reordered for each
of 5 categories: 0, 1, 2, 3, and 4 or more spawns. Heritability of spawn numbers
was 0.20, with a 95% confidence interval of 0.06–0.43, indicating that
this trait can be improved by selective breeding.
Programa de Acuacultura, Centro de Investigaciones Biológicas del Noroeste
(CIBNOR)
Mar Bermejo 195,
AP 128 La Paz B.C.S. 23090,
Mexico;
email of A. Ibarra: aibarra@cibnor.mx
FIRST RESULTS OF GREATER AMBERJACK (SERIOLA DUMERILI) LARVAL
REARING IN MESOCOSM
N. Papandroulakis, C.C. Mylonas, E. Maingot, P. Divanach-2005
Aquaculture 250 (1-2): 155-161
Abstract:
Species diversification is considered a major approach for the sustainable development
of aquaculture. The greater amberjack (Seriola dumerili) has particular characteristics–advantages
making it an appropriate candidate: high growth rate, large size, and established
worldwide market. In the present study, the mesocosm method for larval rearing
was applied, since it has been shown to be effective in the larval rearing of
several species so far. This method is a semi-intensive technology, based on
daily exogenous food addition, but also having the capacity of some endogenous
productivity. Greater amberjack eggs were obtained from wild-caught fish matured
in captivity in 6 years, after induced spawning with implants containing gonadotropin-releasing
hormone agonist (GnRHa). A total of 9800 eggs survived after embryo appearance
and were incubated in a 40-m3 tank with natural seawater of 40 psu. Rearing
lasted 40 days. After mouth opening on day 2 post hatching, exogenous feeding
with rotifers, Artemia nauplii and inert feed was initiated, while endogenous
produced copepods contributed as food for the larvae from day 7 post hatching
onwards. During rearing, larvae grew with an exponential rate of 0.073 day-1
in terms of total length (TL), and reached 39.9 ± 5.4 mm and 0.5 ±
0.1 g body weight at the end of the trial. All larvae inflated their swim bladder
and completed metamorphosis at about 5 mm and 8 mm TL, respectively. Schooling
behavior was first observed when larvae reached 9–10 mm TL, while aggression
against the smallest individuals was first noticed the same period. The final
population of about 350 individuals (3.5% survival) was transferred at the end
of the trial for subsequent on-growing. The results obtained indicate the reliability
of the technology for the larval rearing of the greater amberjack, and also
its appropriateness for diversification with difficult marine species.
Institute of Aquaculture
Hellenic Center for Marine Research
P.O. Box 2214
71003, Heraklion, Crete
Greece
email of N. Papandroulakis: npap@her.hcmr.gr
BREEDING, REARING AND FEEDING STUDIES IN THE CLEANER GOBY
GOBIOSOMA EVELYNAE
Ike Olivotto, Alessio Zenobi, Arianna Rollo, Beatrice Migliarini, Matteo Avella,
Oliana Carnevali-2005
Aquaculture 250 (1-2): 175-182
Abstract:
Breeding and rearing some of the species most commonly used in the aquarium
trade actually represent an economical and ecological tool for broadening development,
thus the present study investigates captive breeding and rearing of a small
goby, the cleaner goby Gobiosoma evelynae.
Egg clutches were obtained from two couples maintained in 100-L tanks under
controlled conditions. Eggs were laid in PVC pipes and the male normally guarded
the nest until the fry hatched.
Hatching took place 168 h post-fertilization at 25 °C. Larvae were divided
into different experimental groups and fed on different HUFAs enriched feeding
combinations: naked Euplotes sp. ciliates and small rotifers Brachionus rotundiformis
(Group A), small rotifers B. rotundiformis and larger ones Brachionus plicatilis
(Group B) and larger rotifers B. plicatilis solely (Group C).
Significantly higher survival rates (50% juveniles) were observed in larvae
fed on the naked ciliate Euplotes sp. and smaller rotifers B. rotundiformis
with respect to larvae fed on the larger one B. plicatilis (10% juveniles).
In larvae fed on the smaller rotifer B. rotundiformis followed by the larger
B. plicatilis, a 35% survival rate was observed. From these feeding studies,
it is evident that significant differences in survival rates are already evident
from day 3 post-hatch, indicating that marine ciliates are the key organism
to improve G. evelynae larvae survival and thus an alternative food source to
copepod nauplii and rotifers.
Dipartimento di Scienze del Mare
Università Politecnica delle Marche
via Brecce Bianche
60131 Ancona
Italy
email of O. Carnevali: o.carnevali@univpm.it
THE EFFECTS OF IONIZING RADIATION ON THE REPRODUCTIVE CAPACITY
OF ADULT PENAEUS (MARSUPENAEUS) JAPONICUS (BATE)
Melony J. Sellars, Bernard M. Degnan, Lyle E. Carrington, Nigel P Preston-2005
Aquaculture 250 (1-2): 194-200
Abstract:
The reproductive capacity of adult Penaeus (Marsupenaeus) japonicus (Bate) was
assessed after exposure to ionizing gamma radiation from a cobalt-60 source.
Males and females were each exposed to 0, 10 and 20 Gray (Gy) of ionizing radiation
(IR) and reciprocally crossed to give nine mating combinations. Fecundity and
hatch rate of resulting spawnings were used as measures of reproductive capacity.
IR significantly (P < 0.05) reduced the fecundity of females when treated
at 20 Gy compared to 0 and 10 Gy. The mean number of eggs per female for the
0 and 10 Gy crosses was 24,280 ± 4680 and 47,000 ± 9670 respectively,
compared to 11,600 ± 6840 for the 20 Gy crosses. Hatch rates from spawnings
of females crossed with irradiated males were significantly lower (P < 0.05)
than for females crossed with non-irradiated males. The mean hatch rate of spawnings
from females crossed with 0 Gy males was 64.02 ± 8.85% compared to 20.77
± 5.46% for 10 Gy and 11.95 ± 6.13% for 20 Gy male crosses. These
results indicate that IR has a negative impact on the reproductive capacity
of females at 20 Gy, and males at 10 and 20 Gy. However, IR was not found to
be 100% effective at preventing the production of viable offspring using the
reported treatment regimes.
CSIRO Marine Research
233 Middle Street
Cleveland, Qld, 4163
Australia
email of M. Sellars: Melony.Sellars@csiro.au
THE EFFECTS OF SALINITY AND TEMPERATURE ON GROWTH AND SURVIVAL
OF AUSTRALIAN SNAPPER, PAGRUS AURATUS LARVAE
D. Stewart Fielder, William J. Bardsley, Geoff L. Allan, Patricia M. Pankhurst-2005
Aquaculture 250 (1-2): 201-214
Abstract:
The effects of salinity and temperature on performance were determined for Australian
snapper, Pagrus auratus first-feeding to pre-metamorphosis larvae held in 100-l
recirculation tanks. In the first experiment, performance was assessed after
transfer from 35‰ at eight salinity treatments (5‰, 10‰, 15‰,
20‰, 25‰ 30‰, 35‰ and 45‰) in larvae from 3 to
21 days after hatching (dah). Survival of larvae was best within the range of
20–35‰. Final size of larvae was similar within the range of 10–35‰
(6.8 ± 0.1 to 7.1 ± 0.2 mm total length [TL]; 3.0 ± 0.3
to 3.3 ± 0.3 mg wet weight) but larvae were 15% shorter at 45‰.
Final swimbladder inflation and feeding onset of larvae was not affected by
salinity in the range of 10–45‰. The presence of calculi in the
urinary bladder of larvae was correlated positively with increasing salinity
but no relationship between urinary calculi and larval survival was observed.
In a second experiment, performance was assessed after transfer from 21 °C
at seven temperature treatments (15, 18, 21, 24, 27, 30 and 33 °C) in larvae
from 3–21 dah. All larvae transferred from 21 °C to 30 °C and
33 °C died after 3 days and from 21 °C to 27 °C died after 9 days.
Survival was not significantly different between 15 °C and 24 °C. Larval
growth increased as temperature was increased; larvae at 24 °C (4.8 ±
0.2 mg wet weight) were 6-fold heavier than larvae at 15 °C. Swimbladder
inflation of larvae grown at 18 °C, 21 °C and 24 °C was high (65.2
± 18.0% to 86.7 ± 8.8%) and similar but inflation was lower in
15 °C and 27 °C. The incidence of urinary calculi occurred earlier and
in a greater number of larvae when temperature was increased. Feeding onset
was not affected by temperature. In a third experiment, performance was assessed
at combinations of two salinities (20‰ and 35‰) and three temperatures
(18 °C, 21 °C, and 24 °C) in larvae from 3 to 24 dah. Survival of
snapper larvae was not significantly different between these treatments. Growth
was not affected by salinity but larvae increased in size as temperature was
increased and there was no interaction of salinity and temperature. The percentage
of larvae that commenced feeding and inflated their swimbladders was similar
in all treatments. Salinity and temperature influenced the incidence of urinary
calculi and there was an interaction between the parameters. Based on our results
in terms of larval performance (growth), development and survival, we conclude
that the optimal conditions for larval rearing of snapper from first-feeding
(3 dah) to pre-metamorphosis (24 dah) are combinations of salinity from 20‰
to 35‰ and a temperature of 24 °C.
NSW Fisheries, Port Stephens Fisheries Centre
Taylors Beach Road
Taylors Beach, NSW, 2316
Australia
email of D. Fielder: fielders@fisheries.nsw.gov.au
A MODEL FOR EXPERIMENTAL INFECTIONS WITH VIBRIO (LISTONELLA)
ANGUILLARUM IN FIRST FEEDING TURBOT (SCOPHTHALMUS MAXIMUS L.) LARVAE UNDER HATCHERY
CONDITIONS
Miquel Planas, María Pérez-Lorenzo, José Antonio Vázquez,
José Pintado-2005
Aquaculture 250 (1-2): 232-243
Abstract:
Vibriosis is one of the main causes of mortality in all stages of fish. In larvae,
further improvements on the control and knowledge of bacterial diseases require
the development of models for experimental infections. A reproducible model
for in vivo infections of first feeding turbot (Scophthalmus maximus) larvae
with the pathogen Vibrio (Listonella) anguillarum is described. Experimental
challenges were carried out under hatchery conditions considering different
ways of delivery of V. (Listonella) anguillarum strain 90-11-287 serotype O1
to turbot larvae: via rotifers (orally) and via water of the larval rearing
tanks (bath). The effect of the supernatant of the bacteria culture was also
considered and discussed. The model proposed is based on the incorporation of
the bacteria into previously enriched rotifers and the delivery to the larvae
during the rotifer feeding period. The effect of infections was already evident
24–72 h after the first challenged day. Final mortalities (days 8–14)
in infected larvae were 56–72% with respect to unchallenged larvae. Mortalities
achieved by applying the protocol of infection are reliable, reproducible and
adequate for experimental purposes. The model of infection via rotifers proposed
in this study is a useful tool for experimental purposes in the larval rearing
of marine fish.
Instituto de Investigaciones Marinas (C.S.I.C.)
Eduardo Cabello 6
36208 Vigo
Spain
email of M. Planas: mplanas@iim.csic.es
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AN EXPERIMENTAL COMPARISON OF SEDIMENT-BASED BIOLOGICAL FILTRATION DESIGNS
FOR RECIRCULATING AQUARIUM SYSTEMS
Robert J. Toonen, Christopher B. Wee-2005
Aquaculture 250 (1-2): 244-255
Abstract:
Common sediment filtration designs for recirculating systems designed for
marine ornamentals fall largely into two major categories: sandbed and plenum-based
systems. To date, there has been no experimental comparison of the relative
performance of these methods for handling nitrogenous wastes in marine aquaria.
We compared nutrient levels in a factorial design of aquaria: (1) with or
without a plenum; (2) with deep (9.0 cm) or shallow (2.5 cm) sediments; and
(3) with coarse (2 mm) or fine (0.2 mm) mean particle sizes. None of these
experimental treatments have a significant advantage in the processing of
nitrogenous wastes in recirculating aquaria; final ammonia and nitrite concentrations
were below detectable levels, and nitrate concentrations did not differ significantly
among the experimental treatments. After an initial stabilization period,
most experimental treatments responded equivalently to continuous ammonium
input of up to 0.5 mg/l/day. Results were qualitatively similar whether experiments
were carried out in the absence of animals in a lab with nutrient input via
measured dosing of ammonium chloride, or in aquaria with live animals and
natural sediments. Sediment depth and particle size had significant effects
on a variety of water parameter measures throughout the experiment. Overall,
coarse sediments had lower buffering capacity (pH, calcium and alkalinity)
and much higher final phosphate concentrations than fine sediments. Death
rates in the live animal experiments containing shallow sediments were roughly
twice (2.91 ± 0.46) those of the deep sediment trials (1.47 ±
0.46). Regardless, the presence or absence of a plenum had little effect on
water parameters throughout the experiment. These results suggest that there
is little benefit to be gained from the addition of a plenum plate beneath
the sediments in recirculating aquarium designs.
Hawaii Institute of Marine Biology
School of Ocean and Earth Science and Technology, University of Hawaii at
Manoa
P.O. Box 1346
Kaneohe, HI 96744
USA
email of R. Toonen: toonen@hawaii.edu
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LIPID COMPOSITION OF THE GIANT LION'S-PAW SCALLOP (NODIPECTEN SUBNODOSUS) IN
RELATION TO GAMETOGENESIS I. FATTY ACIDS
E. Palacios, I.S. Racotta, E. Kraffe, Y. Marty, J. Moal, J.F. Samain-2005
Aquaculture 250 (1-2): 270-282
Abstract:
Seasonal variations in fatty acid composition in several tissues of a 1-year-old
population of giant lion's-paw scallop Nodipecten subnodosus were analyzed
during gonad development. Samples were taken bimonthly from December 1999
to June 2000, a period in which gonad development was occurring. Fatty acid
accumulation in neutral and polar lipids of the female gonad was concomitant
to the gonad development and presented a maximum in June. Among essential
fatty acids, a specific accumulation was observed only for 20:5n - 3 in the
female gonad, as suggested by an increase in its proportion in the neutral
and the polar fractions. However, no specific accumulation was observed for
22:6n - 3, as its proportion remained relatively constant in both fractions.
We suggest that a specific increase of 22:6n - 3 is not necessary during gametogenesis
because its proportion was high enough for reproductive purposes (20–30%).
Although some data suggest a partial mobilization of polyunsaturated fatty
acids from the muscle and digestive gland to the female gonad during gonad
development, the main supply came directly from the diet. The maximum increase
in total and specific fatty acids in the digestive gland occurred in April
and was maintained in June. These changes reflect either a higher lipid availability
of the food, or the beginning of storage process in the digestive gland. However,
in the female gonad, the maximum increase was observed in June, whereas gonad
development and spawning were observed from April. It is suggested that different
patterns of lipid accumulation in the first (April) and second (June) maturation
processes could be related to the reproductive cycle of this species, which
exhibits an initial facultative maturation during spring and the main reproductive
activity during summer.
Centro de Investigaciones Biológicas del Noroeste (CIBNOR)
Mar Bermejo 195
Col. Playa Palo de Santa Rita, La Paz, BCS 23090
Mexico
email of E. Palacios: epalacio@cibnor.mx
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A COMMENT ON THE METHODOLOGY OF STOCKING EXPERIMENTS
Marcel Fréchette-2005
Aquaculture 250 (1-2): 291-299
Abstract:
Stocking density can have an important influence on the success of aquaculture
operations. However, various aspects of the methodology of published experiments
on stocking density appear problematical. For example, size variation in the
system under study may have determinant effects on yield, survivorship and
estimates of the optimal stocking density. To document whether this might
be a source of concern in scientific advice to aquaculturists, I reviewed
all stocking experiments published in Vol. 1 through Vol. 224 of Aquaculture
and checked whether information about size variation had been reported in
sufficient detail, whether size-sorting had occurred and whether groups of
experimental individuals and cultured individuals had similar size variability.
This was done for experiments on crustaceans and finfish (the corresponding
analysis for bivalves is presented in Fréchette et al. (2005) [Fréchette,
M., Alunno-Bruscia, M., Dumais, J.-F., Daigle, G., Sirois, R., 2005. Incompleteness
and statistical uncertainty in competition/stocking experiments. Aquaculture
246, 209–225]). The analysis clearly shows that the issue of size variability
of test cage populations has been largely overlooked in a large proportion
of experiments.
The study raised other sources of concern. For instance, allometry was overlooked
in a significant proportion of experiments on crustaceans (55%) and finfish
(25%), which caused ration level to be adjusted following inappropriate principles.
The issues of replacement/removal of individuals and of the dimensions of
the variable used to measure stocking level were also examined. Inappropriate
procedures were found in a number of cases. Suggestions are made to deal with
these issues in a more acceptable way. These problems, which may lead to serious
flaws in advice to growers, were not restricted to papers published in Aquaculture.
Institut Maurice-Lamontagne, Ministère des Pêches et des Océans
C.P. 1000
Mont-Joli, Québec
Canada G5H 3Z4
email of M. Fréchette: Frechettem@dfo-mpo.gc.ca
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TANK COLOUR AND DIETARY ARACHIDONIC ACID AFFECTS PIGMENTATION, EICOSANOID PRODUCTION
AND TISSUE FATTY ACID PROFILE OF LARVAL ATLANTIC COD (GADUS MORHUA)
M.P. Bransden, G.M. Butterfield, J. Walden, L.A. McEvoy, J.G. Bell-2005
Aquaculture 250 (1-2): 328-340
Abstract:
We determined the effect of dietary arachidonic acid (20:4n - 6, ARA) and
tank colour (green or grey) on the performance of larval Atlantic cod from
2–28 days post-hatch (dph) using a two-factor, fully orthogonal design.
Performance of larvae was assessed by evaluating growth, whole body fatty
acid (total and polar lipid) profile, whole body eicosanoid (prostaglandins
(PG) E and F) production and pigmentation. Rotifers were enriched on one of
four experimental emulsions containing graduated ARA concentrations, and fed
to 6 replicate tanks (3 each of green and grey colour) of larvae. Tank colour
had no significant effect on larval growth or survival at 28 dph. Significant
differences in growth (length and dry weight) were detected among diets, although
no direct correlation was recorded between growth and dietary ARA. The whole
body fatty acid profile from the total and polar lipid fractions of larvae
was directly influenced by the diet. Diet did not influence pigmentation,
but larvae held in green tanks had significantly elevated pigmentation on
both their head and body compared to those held in grey tanks. The interaction
between diet and tank colour had a significant effect on total PGE concentration,
while total PGF was not influenced by diet or tank colour. We propose that
larvae adapt to their background tank colour by changes in pigmentation (melanophore)
dispersal modulated by an elevation of circulating a-melanocyte stimulating
hormone, which in turn influences total PGE production. To our knowledge this
is the first study to demonstrate a relationship between pigmentation and
eicosanoids in larval fish, although the biochemical pathways and mechanisms
remain poorly understood.
Marine Research Laboratories, Tasmanian Aquaculture and Fisheries Institute
and Aquafin Cooperative Research Centre
University of Tasmania
Private Bag 49
Hobart, Tasmania, 7001
Australia
email of M. Bransden: Matthew.Bransden@utas.edu.au
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DEVELOPMENT OF THE RADULA AND DIGESTIVE SYSTEM OF JUVENILE BLACKLIP ABALONE
(HALIOTIS RUBRA): POTENTIAL FACTORS RESPONSIBLE FOR VARIABLE WEANING SUCCESS
ON ARTIFICIAL DIETS
Danielle Johnston, Natalie Moltschaniwsky, Jarrod Wells-2005
Aquaculture 250 (1-2): 341-355
Abstract:
We investigated the structural and physiological changes in the radula and
digestive system in juvenile blacklip abalone Haliotis rubra, between 80 and
158 days post settlement (PS) to determine if variable growth on artificial
diets (and prevalence of runts) are due to an inability to efficiently ingest
and digest the diet. Between 80 and 102 days PS, L5 teeth appeared on the
radula and there were fewer lateral serrations, consistent with the adult
form of the animal, suggesting that this development is in preparation for
feeding on macroalgae. Digestive gland complexity (tubule number and density)
increased between 80 and 102 days PS and is consistent with greater enzyme
production and increased digestive efficiency. Of the enzymes studied, laminarinase
and lipase exhibited the highest activities in animals fed a diatom diet,
both significantly increasing with age of the abalone. High laminarinase activities
reflect higher utilisation of the algal polysaccharide chrysolaminarin in
the diatom diet. Ingestion of artificial diet had no adverse effects on the
morphological development of the digestive system, but trypsin activity in
abalone fed the artificial diet was significantly higher than diatom-fed abalone
of similar age, indicative of higher levels of protein in the artificial diet.
Similarly, lipase activity was significantly lower in abalone fed the artificial
diet and may reflect an inability to digest the fish oil component, which
is not found in their natural diet. Future development of artificial diets,
especially for juvenile abalone, should focus on the levels and type of lipid
provided. Runt abalone (i.e. under-developed compared to their siblings) had
radulae similar to much younger 80 days PS abalone and digestive tissue degradation
at 137 days PS is evidence that runts have limited ability to ingest food
and are nutritionally compromised.
School of Aquaculture
Tasmanian Aquaculture and Fisheries Institute
University of Tasmania
Locked Bag 1370
Launceston, Tasmania 7250
Australia
email of D. Johnston: djohnston@fish.wa.gov.au
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TEMPERATURE AND PHOTOPERIOD DRIVE CRASSOSTREA GIGAS REPRODUCTIVE INTERNAL CLOCK
Caroline Fabioux, Arnaud Huvet, Pierrick Le Souchu, Marcel Le Pennec, Stéphane
Pouvreau-2005
Aquaculture 250 (1-2): 458-470
Abstract:
This study examined the gametogenic cycle of Crassostrea gigas in controlled
conditions over one year, with a focus on the initiation of gametogenesis.
This work analysed also the role of temperature and photoperiod in the regulation
of oyster reproduction. Broodstock were maintained in natural (NC), accelerated
(AC) and perpetual winter (WC) conditions of temperature and photoperiod,
with feeding ad libitum. Qualitative and quantitative analyses of the reproductive
pattern were performed using biometric measurement approach, sex ratio determination,
histology and a gonad filling index. Each experimental treatment led to different
strategies for growth and resource allocation. The gametogenic cycle, appeared
entirely modulated, accelerated or delayed, by coupled temperature/photoperiod
parameters. Temperature played a key role in gonial mitosis regulation. Gonia
proliferation was set off and sustained by winter temperature (8–11
°C) whatever the physiological state of oysters. Maturation of germ cells
appeared to be a function of temperature and could proceed at low temperature,
while ripe oysters were obtained at 8 °C in winter conditioning. The three
conditioning methods used in this study, allowed the production of gametes
throughout the year, including in the autumnal resting period. Moreover, stocks
of ripe oysters could be maintained at low temperature during several months
to produce spat when desired for aquaculture production.
UMR Physiologie et Ecophysiologie des Mollusques Marins
Ifremer
B.P.70
29280 Plouzané,
France;
email of C. Fabioux: Caroline.Fabioux@ifremer.fr
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THE MORPHOLOGY AND OCCURRENCE OF JAW AND OPERCULUM DEFORMITIES IN CULTURED
BARRAMUNDI (LATES CALCARIFER) LARVAE
M.R. Fraser, R. de Nys-2005
Aquaculture 250 (1-2): 496-503
Abstract:
Morphological deformities are a problem that hinders the production of cultured
finfish worldwide. Barramundi Lates calcarifer, like many other cultured species,
suffers from a range of skeletal deformities including those of the jaw and
opercula. This study describes the morphology of jaw and opercula deformities
and their occurrence during the larval development of L. calcarifer. Samples
of a minimum of 65 larvae were collected every second day at a commercial
hatchery from 2 days after hatch (DAH) until 38 DAH. The jaw deformities recorded
included shortened upper jaw, shortened lower jaw, twisted lower jaw and a
deformity not previously described for any other species, termed ‘pinched
jaw’, which affects both the upper and lower jaws. All jaw deformities
were first observed at 18 DAH, 12 days after ossification of the affected
structures. Deformities ranged in frequency between 4.24% and 35.71% of samples
with no discernable pattern over time. The maximum frequency of the shortened
upper jaw and shortened lower jaw deformities was 9.09% and 7.35%, respectively.
‘Pinched’ upper and lower jaw had a maximum frequency of 0.65%
and 9.30%, respectively, while the co-occurrence of upper and lower ‘pinched’
jaw on an individual ranged in frequency between 0.00% and 3.90%. The twisted
lower jaw deformity ranged between 0.00% and 7.79%. Jaw deformities co-occurred
on the same individual for a significant proportion of the deformed population
including shortened lower jaw and ‘pinched’ lower jaw, and ‘pinched’
lower jaw and ‘pinched’ upper jaw.
James Cook University,
School of Marine Biology and Aquaculture,
Townsville, QLD, 4811,
Australia;
email of R. Denys: rocky.denys@jcu.edu.au
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