Ontogenetic Development and Nutritional Requirements in Early Life Stages of the European Lobster ( Homarus gammarus , L.)
The European lobster, Homarus gammarus , is an ecological and economically important species. Historically, it has been subjected to intense fishing pressure that caused the decline of several wild populations. To counteract the decrease in annual landings various stock enhancement programs have bee...
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| Format: | Book |
| Language: | English |
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DTU Aqua
2021
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| Online Access: | https://orbit.dtu.dk/en/publications/cc0bee56-1810-4380-8e78-a0f0250446de https://backend.orbit.dtu.dk/ws/files/266144672/Renata_Goncalves_thesis.pdf https://backend.orbit.dtu.dk/ws/files/266144674/Renata_Goncalves_correction_sheet.pdf |
| Summary: | The European lobster, Homarus gammarus , is an ecological and economically important species. Historically, it has been subjected to intense fishing pressure that caused the decline of several wild populations. To counteract the decrease in annual landings various stock enhancement programs have been launched around Europe. These initiatives are supported by hatchery-reared juvenile lobsters that are released into natural habitats. The commercial cultivation of the species is also attracting considerable attention and H. gammarus is currently considered an emerging aquaculture species. However, the economic viability of European lobster hatcheries is hampered by several drawbacks including low survival and growth rates, the strong cannibalistic nature of the species, and the dependence on live, fresh, and frozen diets. The main purpose of this Ph.D. project was to increase knowledge on the metabolism and nutritional requirements of H. gammarus early stages and thus provide solutions to nutritional challenges faced by hatchery production units. Specific goals were: (1) to identify ontogenetic changes in the digestive capacity and potential nutritional requirements of larvae and postlarvae; (2) screen macronutrient levels in the design of formulated feeds for early juvenile stages; (3) assess the potential of alternative and more sustainable ingredients in formulated feeds for juvenile lobsters; and (4) evaluate the effect of dietary composition on the resilience of juvenile H. gammarus to environmental variation. For that, five studies were conducted. In the first study, the digestive enzymatic activity (trypsin, amylase, and lipase) and biochemical indices (RNA:DNA ratios, proximate and lipid class composition) were measured in stages I, II, and III larvae, and stage IV postlarvae. Main results showed that lipase activity increased from stage I to stage III but not further, suggesting the increasing importance of lipids during the first three larval stages. Amylase activity increased significantly at stage IV ... |
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