MULTIPLE SPAWNING IN THE TROPICAL SQUID PHOTOLOLIGO SP - WHAT IS THE CAST IN SOMATIC GROWTH

This study assesses the potential of the tropical loliginid squid Phot ololigo sp. to lay multiple batches of eggs and examines changes in so matic growth during reproduction. Histological analysis of the ovary a nd the relative size of the oviduct to mantle weight and ovary weight were used to determine the potential for multiple spawning. Ovaries of mature females always had immature and mature oocytes present, sugges ting that not all the oocytes were maturing simultaneously and that mu ltiple batches of eggs were being produced. Furthermore poor correlati ons of oviduct weight with body size and ovary weight indicated that m ature oocytes were not accumulating in the oviduct for a single spawni ng event. Both these observations supported the hypothesis that Photol oligo sp. has the potential to lay multiple batches of eggs throughout its life. Specific growth rates, length-weight relationships, relativ e growth of somatic and reproductive tissue and microscopic assessment of muscle tissue were compared between immature and mature females. G rowth rates of immature females were almost twice as fast as those of mature females. Mature females also had no large muscle fibres present , suggesting that energy for reproduction was mobilised from the muscl e tissue.