Estimation of Energy Budget for Gonadal Development, Migration and Spawning of eels (Anguilla anguilla L.) inhabiting the Egyptian Lagoons PDF

Keywords

silver eel, migration, lipids

Abstract

The total body energy stores of European silver eel (Anguilla anguilla L.) at the start of migration is sufficient to fulfill all biological activities which begin with active migrations. We used a slightly modified model to evaluate the energy budget of eel during gonadal development, migration and spawning. Lipid and protein are the main energy components of eel body; lipid is the principal source and protein represents the second source of energy. Lipid energy, as a percentage of total energy, was 58.2 for male and 67.9 for female yellow eels. These values were smaller than those calculated for male (76.3) and female silver eels (80.1). Lipid energy of immature testes amounted to 72.5%, while immature ovaries contained 83.9%. Further gonadal development showed an increase in lipid energy up 80.3% at time of formation of spermatozoa in the ripe male and 86.4% at the time of ripe ova in the female ovary. About 25.1% and 20.3% of the total energy expenditure seemed to be utilized in oogenesis and spermatogenesis, respectively. Approximately 17.1 and 15.8% of total energy was utilized for ovulation and spermiation, respectively. During migration and simultaneous routine metabolism (ER) about 35.7 and 34.2% of the total energy was utilized by female and male silver eels, respectively.The energy of routine metabolism was higher in male than in female silver eel, with values of 9.6% and 6.0%, respectively.