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  • 1
    Electronic Resource
    Electronic Resource
    Ontogenetic variations of thermal optimum for growth, and its implication on thermolabile sex determination in blue tilapia (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 61 (2002), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Knowledge of how the optimum temperature for growth (T°opt) varies during ontogeny, and how close it is to the temperatures that induce phenotypic masculinization is fundamental to the understanding of the evolution of thermolabile sex determinism (TSD) in fishes. In blue tilapia Oreochromis aureus, T°opt is 32·6° C at the start of exogenous feeding (10mg fish) and it decreases by c. 1° C each time that the fish body mass increases by an order of magnitude. Temperatures 〈35° C are not sufficient to induce complete phenotypic masculinization. Based on a multiple-regression model (r2=0·938) plotting growth against body mass and water temperature, genotypically female tilapia living at high temperatures during the thermosensitive period (21–28 days) and being reversed into phenotypic males would incur an initial growth disadvantage over fish living at T°opt, but not over those living at slightly colder temperatures (27–29° C). This initial disadvantage would be later compensated for by faster growth because of between-sex growth dimorphism to the detriment of phenotypic females. These arguments suggest that there is no definite pressure against the selection of TSD in blue tilapia and probably other Oreochromis spp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2002.tb00902.x
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  • 2
    Electronic Resource
    Electronic Resource
    Sibling cannibalism in dorada under experimental conditions. (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 57 (2000), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cannibalism among embryos and larvae of Brycon moorei (Characidae) occurs during daytime and night-time, and persists under permanent darkness. Embryos and larvae of dorada-provisioned with formulated feed over the first week of exogenous feeding did not survive, except for those exerting cannibalism. When offered alternative fish prey [embryos of Prochilodus magdalenae (0·5–0·8 mg) and Oreochromis niloticus (9–10 mg)], 1-day-old embryos of dorada preferred preying on these, thereby reducing early cannibalism. However, this promoted depensatory growth and more intense cannibalism later in the larval stage. Dorada provisioned with Artemia nauplii in excess showed more homogeneous growth and higher survival, most cannibalistic acts being restricted to the first 24 h of exogenous feeding, just after oral teeth were fully developed (21 h after hatching). Provisioning dorada with Artemia nauplii a few hours before their oral teeth were fully developed reduced early cannibalism from 41 to 15%. High proportions of deformed fish caused higher mortality, both directly and indirectly, as they promoted early cannibalism, depensatory growth and more intense cannibalism among larvae. The initial sorting of embryos, based on their occupation of the water column improved survival significantly during the first week of exogenous feeding, up to 52% in progenies containing 〈10% of deformed fish. Size-grading of larvae and young juveniles over the next 2 weeks reduced cannibalism to 2·6 and 1·9% day−, in the first and second weeks, respectively. These results indicate that cannibalism in dorada can be mitigated efficiently through appropriate rearing procedures, and open promising perspectives for the intensive culture of this fast-growing tropical species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2000.tb02208.x
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  • 3
    Electronic Resource
    Electronic Resource
    Appearance of pathogenic Naegleria fowleri (Amoebida, Vahlkampfiidae) in artificially heated water of a fish farm
    Amsterdam : Elsevier
    Aquaculture 35 (1983), S. 73-78 
    Details
    ISSN: 0044-8486
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0044-8486(83)90071-6
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  • 4
    Electronic Resource
    Electronic Resource
    Sibling cannibalism in dorada under experimental conditions. (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 57 (2000), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cannibalism among embryos and larvae of Brycon moorei (Characidae) occurs during daytime and night-time, and persists under permanent darkness. Embryos and larvae of dorada provisioned with formulated feed over the first week of exogenous feeding did not survive, except for those exerting cannibalism. When oered alternative fish prey [embryos of Prochilodus magdalenae (0·5–0·8 mg) and Oreochromis niloticus (9·10 mg)], 1-day-old embryos of dorada preferred preying on these, thereby reducing early cannibalism. However, this promoted depensatory growth and more intense cannibalism later in the larval stage. Dorada provisioned with Artemia nauplii in excess showed more homogeneous growth and higher survival, most cannibalistic acts being restricted to the first 24 h of exogenous feeding, just after oral teeth were fully developed (21 h after hatching). Provisioning dorada with Artemia nauplii a few hours before their oral teeth were fully developed reduced early cannibalism from 41 to 15%. High proportions of deformed fish caused higher mortality, both directly and indirectly, as they promoted early cannibalism, depensatory growth and more intense cannibalism among larvae. The initial sorting of embryos, based on their occupation of the water column improved survival significantly during the first week of exogenous feeding, up to 52% in progenies containing 〈10% of deformed fish. Size-grading of larvae and young juveniles over the next 2 weeks reduced cannibalism to 2·6 and 1·9% day −1, in the first and second weeks, respectively. These results indicate that cannibalism in dorada can be mitigated eciently through appropriate rearing procedures, and open promising perspectives for the intensive culture of this fast-growing tropical species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2000.tb02207.x
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  • 5
    Electronic Resource
    Electronic Resource
    Sibling cannibalism among juvenile vundu under controlled conditions. II. Effect of body weight and environmental variables on the periodicity and intensity of type II cannibalism (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 54 (1999), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cannibalism among starved groups of juvenile (19–48 days old) vundu catfish Heterobranchus longifilis was 66·5% nocturnal, and its impact under modified day length was proportional to the duration of the dark phase. Shallow depth and high population density decreased the intensity of cannibalism, whereas low density and deeper environments had an opposite effect. The presence of refuges had no significant effect on cannibalism. The maintenance (Rmaint) and maximum (Rmax) daily food rations (% day−1) of cannibals feeding on live prey were modelled as Rmaint=3·899 WC0·327 (r2=0·684; d.f.=31), and Rmax=49.545 WC0·321 (r2=0·999; d.f.=5), where WC was the body weight of the cannibal (g). The latter model indicated that the impact of a cannibal on a population decreased by a 20% margin each time the cannibal doubled its body weight, and suggested that cannibalism among vundu would become insignificant for cannibals heavier than 30 g. The significance of these findings is discussed within the contexts of vundu aquaculture and of general, conceptual models of the dynamics of cannibalism among fishes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1999.tb00615.x
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  • 6
    Electronic Resource
    Electronic Resource
    Nutritional and animal husbandry aspects of rearing early life stages of Eurasian perch Perca fluviatilis (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of applied ichthyology 12 (1996), S. 0 
    Details
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The Eurasian perch Perca fluviatilis larviculture can be divided into three major areas: the ontogeny of the digestive system, the nutritional requirements and, the growth, production and cannibalism in different culture systems. Ontogeny of digestive system of larvae and juveniles, i.e., the morphological and histological characteristics of the digestive system (including the digestive tract, liver, pancreas and pyloric caeca), is described from hatching up to 1-month-old. Preliminary data on proteolytic activities (pepsin, trypsin and chymotrypsin) during larval growth and weaning on dry diet are also provided. The effects of diet (type of live prey, live food vs. dry or mixed diet) on survival and growth of perch are compared and discussed. In many perch larvae, mouth size constitutes a limiting factor to an optimal utilization of Artemia nauplii from hatching onwards. However, this diet can support satisfactory survival and growth in larger larvae, usually obtained from large breeders. Although perch larvae ingest dry food after yolk sac absorption, survival and growth rates are very low at that stage, compared with results obtained with live food and mixed diet. Weaning experiments performed at different larval and juvenile body weights demonstrated that fish can be trained to accept and to use a dry diet efficiently as a unique food supply starting at 50 mg. Some data related to the nutritional requirements (feeding level, dietary protein, fatty acids) of perch larvae are provided. Juvenile production in different culture conditions (fertilized ponds, green water tanks, recirculated system) indicated that the optimal system for the production of weaned fry was the semiintensive one. In this method, combining an enhanced production of natural plankton and a regular supply of Artemia nauplii and dry food after 44 days of rearing, survival rate varied from 9.2 to 38.6% and body weight from 350 to 950 mg, depending on temperature and stocking densities (400–4000 eyed eggs m−2).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0426.1996.tb00082.x
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  • 7
    Electronic Resource
    Electronic Resource
    A preliminary study of parasites and diseases of perch in an intensive culture system (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of applied ichthyology 12 (1996), S. 0 
    Details
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The recent development of intensive rearing of European perch Perca fluviatilis in warm water effluents revealed important pathological problems. This study gives a preliminary overview of parasites and diseases encountered in experimental perch farming. No virus has been recorded since the beginning of the experiments in 1993. By contrast, mass mortality caused by bacterial disease alone or associated with other pathogens were frequently observed. The main identified bacterial species were: Aeromonas sp., A. veronii, A. hydrophila, Streptococcus sp., Staphylococcus sp., Vibrio fluviatilis and Enterobacter agglomerans. Protozoans were the most common parasites observed on cultured P. fluviatilis. High mortality rate due to Ichthyobodo necator and Trichodina sp. may take place at different stages of perch rearing. In contrast, the infestation by Ambiphrya sp. and Heteropolaria sp. was size- or age-related; these two ciliates infested perch weighing 〈 1 g and 〉 20 g, respectively. In spite of the presence of other parasites such as Ichthyophthirius multifiliis, Hexamita spp., Gyrodactylus sp. and Argulus sp. in the rearing system P. fluviatilis does not appear to be affected. Further abnormalities or diseases inherent to intensive culture systems are also described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0426.1996.tb00089.x
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  • 8
    Electronic Resource
    Electronic Resource
    Intensive culture of juvenile and adult Eurasian perch (P. fluviatilis): effect of major biotic and abiotic factors on growth (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of applied ichthyology 12 (1996), S. 0 
    Details
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Recent developments in Eurasian perch (Perca fluviatilis) larval rearing and weaning techniques allow large-scale intensive rearing tests, both with juveniles and adults. This review presents the results of experiments conducted in a commercial scale production environment (0.5–1.6m3 flow-through tanks) and focuses on the most relevant factors influencing growth and production in intensive rearing systems. Combined effects of food ration and temperature showed that the maximum growth rates (0.06–1.80 g fish−1 day−1 for 1–300 g fish) were observed at 23°C. The thermal range for intensive rearing of perch extends at least down to 11°C (growth rate equivalent to 29% of that observed at 23°C). The maximum daily food ration (9–4.5% lipid; 57–44% crude protein) at 23°C resulted in feed conversion rates from 1.1 to 2.0 in fish ranging from 1 to 150g and was modelled as follows (R2= 0.89): Rmax (% day−1) = 7.60 w (weight, g)−0.31. Juvenile (1–15g) perch reared at 10000 fish m−3 showed a growth rate of 0.2 g fish−1 day−1, thus 67% higher than at 400 fish m−3. In the most intensive rearing trials (124kg m−3), the maximum production rate observed was 2.6 kg m−3 day−1.Growth heterogeneity constitutes a major constraint in perch culture. Size grading experiments resulted in the emergence of fast-growing fish in each sorted group. In addition, the sorting process caused the productivity to be slightly lower (5–6%) than in non-sorted populations of the same origin and body weight. Mass mortality may take place at any stage of perch rearing within the 1–200 g body weight range. In general, an overall 50% survival rate was recorded after 14 months. Parasites, bacteria and fungi were the most frequently encountered causes of mortality. The occurrence and impact of diseases were largely reduced in recirculating systems where the survival rate is 70% higher than the values observed in flow-through rearing systems. In intensive rearing systems at 23°C and at maximum stocking biomass of 50 kg m−3, 44-day- old weaned perch juveniles (ranging from 0.5 to 1 g initial body weight) reached an average body weight of 130–150 g after 1 year of rearing. Still, this marketable size was reached about 3 months earlier by fast growing individuals within the population.The intensive culture of perch at a constant 23°C water temperature allowed much higher growth rates than usually observed in conventional, extensive systems under natural thermal regimes. Constant temperatures also inhibited the sexual maturation in females. Further improvements in growth and productivity in intensive perch rearing will closely rely on techniques such as the selection of fast-growing strains, monosex female or sterile triploïd fish production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0426.1996.tb00085.x
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  • 9
    Electronic Resource
    Electronic Resource
    Cathepsin L in eggs and larvae of perch Perca fluviatilis: variations with developmental stage and spawning period (1999)
    Springer
    Fish physiology and biochemistry 21 (1999), S. 59-64 
    Details
    ISSN: 1573-5168
    Keywords: egg quality ; enzyme ; protease ; reproduction ; stress test ; teleost
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study describes changes in cathepsin L activity during early development in Eurasian perch (Perca fluviatilis) and determines to which extend a precocious proteolysis of the yolk reserves by activated cathepsin L could be involved in the seasonal decline of egg and larval quality. During embryogenesis and early larval stages, samples were collected for determination of fertilization and hatching rates, assays of cathepsin L activity, and evaluation of larval resistance to stress (osmotic shock and fasting). Cathepsin L activity increased significantly during the embryonic development, reaching a maximum of 177.1±12.3 nmol min−1mg fresh weight−1 on day 1 post-hatching and significantly decreasing on day 3. Activity increased significantly during the spawning season and individual variations between egg strands became very high during the second half of the spawning period. An inverse relationship was established between the cathepsin L activity in 7-day old eggs and the decrease of hatching rate. A negative exponential regression was calculated between the cathepsin L activity of eggs and the resistance of corresponding newly-hatched larvae to osmotic shock. Resistance to fasting was significantly reduced in larvae from eggs with cathepsin L activity higher or lower than 20 nmol min−1 mg−1 (lethal time50=4.7±0.7 and 3.5±0.4 days, respectively). The involvement of cathepsin L in the degradation of yolk reserves and its potential consequences on the quality of perch eggs and larvae are discussed in relation to results reported in salmonid fishes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007714314072
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamics of total lipids and fatty acids during embryogenesis and larval development of Eurasian perch (Perca fluviatilis) (2000)
    Springer
    Fish physiology and biochemistry 23 (2000), S. 233-243 
    Details
    ISSN: 1573-5168
    Keywords: embryogenesis ; fatty acids ; feeding ; larval development ; lipids ; Perca fluviatilis ; starvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Total lipid and fatty acid compositions were determined during embryogenesis and larval development in Eurasian perch (Perca fluviatilis). During embryonic development, perch did not catabolize lipids and fatty acids as an energy source. However, during larval development, there was an exponential relationship between the decrease in total lipids and the duration of starving (r 2=0.9957) and feeding (r 2=1). The duration of the starving period (10 days post hatching) was shorter than the feeding period (35 days post hatching). In both starved and fed larvae, there is an apparent preference in utilization of polyunsaturated fatty acids followed by monounsaturated fatty acids. Saturated fatty acids were utilized by neither fed perch larvae nor by starved perch larvae. In starved larvae, palmitoleic 16:1(n-7) and oleic 18:1(n-9) acids were the preferentially monounsaturated fatty acids catabolized and their contribution as energy source from total fatty acids catabolized over the first week was 37.6%. In fed larvae, these 2 nutrients were also the most monounsaturated fatty acids utilized as energy source and possibly also as precursors for others monounsaturated fatty acids biosynthesis. During the same period and among (n-6) polyunsaturated fatty acids, starved perch utilized less linoleic 18:2(n-6) and arachidonic 20:4(n-6) acids than fed larvae despite the fact that the starved perch were in more unfavorable nutritional conditions. In the case of (n-3) fatty acids, starved larvae utilized more linolenic acid 18:3(n-3) and less eicosapentaenoic 20:5(n-3) acid and docosahexaenoic 22:6(n-3) acid than fed perch. Starved larvae probably spared 20:5(n-3) and 22:6(n-3) for physiological functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007891922182
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