Red porgy (Pagrus pagrus) larval feeding performance and behavior at the onset of exogenous feeding |
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| Authors: | Carlos A.P. Andrade,Iolanda P.G. Brazã o,Marilyn P. Ferreira,Maria T. Dinis |
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| Affiliation: | a Centro de Maricultura da Calheta, Direcção Regional de Pescas, 9370-133 Vila da Calheta, Madeira, Portugalb Universidade da Madeira, Caminho da Penteada, 9020-105 Funchal, Portugalc CCMAR, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugald Centro de Oceanografia, Laboratório Marítimo da Guia, FCUL, Avenida N. S. do Cabo 939, 2750-642 Cascais, Portugal |
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| Abstract: | The feeding performance and behavior at the onset of exogenous feeding, 3 to 4 days after hatching (DAH), were studied in red porgy Pagrus pagrus larvae. Similar feeding efficiency and intensity were achieved for two feeding treatments (live or freeze-dried rotifers) suggesting that prey movement is not decisive for their detection and capture and demonstrating that at first feeding red porgy larvae can ingest inert food. Larvae feeding performance was not affected by a diet shift between treatments. Based on maximum rotifers consumption and gut evacuation time at 18 °C, the daily ration was estimated as 14.035 μg, considering 14 h of feeding and a 25% egg:female rotifer ratio. Larval swimming activity measured by video recording showed a close association with gut fullness and similar swimming patterns for 3 and 4 DAH larvae. However, 20.3% larger mouth gape and 54.6% higher swimming speed of the older larvae should provide a better feeding performance and more energy needed for growth. |
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| Keywords: | LS, Standard Length, measured from tip of the upper jaw to the end of the notochord UJL, Upper Jaw Length, measured from tip of snout to the posterior end of the maxilla MH, Mouth Height, considering a 90° opening angle, was calculated as follows, MH = UJL&lowast &radic 2 (Shirota, 1970) BL, Body Total Length, a measure of distance traveled by larvae GET, Gut Evacuation Time, described by best-fit regression model of decreasing gut contents over time CMAX, Maximum Consumption, determined by the highest mean number of rotifers in the gut F, Rotifers egg:female ratio MD, Dry Mass of rotifers, calculated using Yú fera et al. (1997) equation for Brachionus rotundiformis, MD = 85 + 209 F0.218 |
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