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Red porgy Pagrus pagrus:ontogeny and culture methods
| Resumo: | Red porgy is a candidate species for the diversification of aquaculture production (Chapter 1). Different larvae ontogenetic stages and associated culture methods are critical to larvae development and survival, being considered as hatchery production bottlenecks and investigated in the course of the thesis. Larvae rearing trials were conducted using mesocosm semi-intensive methodologies (Chapter 2), as low larval densities and balanced endogenous and exogenous sources of live feed are appropriate for larval studies when there is limited knowledge of nutritional requirements. Larvae ontogeny was characterized by strong positive allometric growth of body depth at anus (BDA) (Chapter 3). A morphometric index combining BDA with standard length provided better estimates of larvae growth. Cannibalism coincided with the development of acidic digestion, therefore suggesting that this behaviour is prompted by physiological/energetic factors. Differences found in larvae morphological, histological and histochemical traits, and ecology in mesocosm (Chapter 4) compared to larvae from intensive culture were attributed to the faster larval growth and low hydrodynamic conditions in the former. Feeding performance and behaviour at the onset of exogenous feeding is not affected by the movement of prey or by diet shifts between live and freeze-dried rotifers (Chapter 5). Larvae change feeding mode from 3 to 4 DAH, to a no stopping stage between feeding and evacuation phases. The daily ration was estimated from maximum rotifers consumption and gut evacuation time. Advances in the evaluation of egg hatching rate and live food (rotifers) balance improved control over the larvae population in the large mesocosm rearing tanks (Chapter 6). The early introducing of Artemia at low densities in larval weaning produced comparable results on growth performance, survival and biochemical indicators of physiological status as a late supply regime (Chapter 7). Digestive enzymes and fatty acids were selected as reliable indicators of red porgy larvae nutritional condition. |
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| Autores principais: | Andrade, C. A. P. |
| Assunto: | Aquacultura Piscicultura Teses de doutoramento - 2012 |
| Ano: | 2012 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Red porgy is a candidate species for the diversification of aquaculture production (Chapter 1). Different larvae ontogenetic stages and associated culture methods are critical to larvae development and survival, being considered as hatchery production bottlenecks and investigated in the course of the thesis. Larvae rearing trials were conducted using mesocosm semi-intensive methodologies (Chapter 2), as low larval densities and balanced endogenous and exogenous sources of live feed are appropriate for larval studies when there is limited knowledge of nutritional requirements. Larvae ontogeny was characterized by strong positive allometric growth of body depth at anus (BDA) (Chapter 3). A morphometric index combining BDA with standard length provided better estimates of larvae growth. Cannibalism coincided with the development of acidic digestion, therefore suggesting that this behaviour is prompted by physiological/energetic factors. Differences found in larvae morphological, histological and histochemical traits, and ecology in mesocosm (Chapter 4) compared to larvae from intensive culture were attributed to the faster larval growth and low hydrodynamic conditions in the former. Feeding performance and behaviour at the onset of exogenous feeding is not affected by the movement of prey or by diet shifts between live and freeze-dried rotifers (Chapter 5). Larvae change feeding mode from 3 to 4 DAH, to a no stopping stage between feeding and evacuation phases. The daily ration was estimated from maximum rotifers consumption and gut evacuation time. Advances in the evaluation of egg hatching rate and live food (rotifers) balance improved control over the larvae population in the large mesocosm rearing tanks (Chapter 6). The early introducing of Artemia at low densities in larval weaning produced comparable results on growth performance, survival and biochemical indicators of physiological status as a late supply regime (Chapter 7). Digestive enzymes and fatty acids were selected as reliable indicators of red porgy larvae nutritional condition. |
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