New insights on Reproductive strategy of swordfish (Xiphias gladius) In the Southwestern Indian OCean F.Poisson. Fauvel C.

Part 2: Fecundity and spawning pattern

Close to over-exploitation (IOTC) 35,000 Tonnes 1990

Aims of this study Monitor the gonadal development of individuals around Reunion Island, Review all information available in the Indian and western Pacific Oceans.

Sampling program Over 32 CONSECUTIVE MONTHS 52 trips onboard domestic longliners 294 days at sea, 235 longline sets 1727 gonads sampled

Spawning occurs from October to April Gonadal Index (Hinton et al. 1996) Spawning Threshold value 1.375

Spawning season is longer for bigger (older) females

The Big individuals arrived at the beginning of the Spawning season

Sex ratio fluctuated seasonaly according to SST

Batch fecundity increases with the fish weight (age) Millions of oocytes

Big Old Fat Fecund Female Fish Big Old Fat Fecund Female Fish (BOFFFF) hypothesis (Longhurst 2002, Berkeley et al. 2004) Diameter of eggs ☺ ☺ offsprings Viability ☺ Growth BOFFFF more biologically valuable

Spawning activity is localized in discrete areas

Conclusion Spawning activity localised in discrete areas Synchronised movements between spawning ground and neighboring regions Major role of the BOFFF in the reproductive capacity

Confirm migration pattern (homing pattern) PROSPECTS Confirm migration pattern (homing pattern) Consider the protection of BOFFFF How to preserve the population age structure Fishing closure ? Protected marine areas? Gear selectivity ?

Acknowledgements This project was an financed by the European Union (FEDER), and the Conseil Régional and Conseil Général de La Réunion. The authors would like to express their gratitude to the skippers who volunteered to allow scientific observers on board their vessels and to all people involved in the sampling. We thank the fishery industry of Reunion Island for their outstanding support of the “Programme Palangre Réunion” (PPR) project.

THANKS FOR YOUR ATTENTION DO SWORDFISH ♂ PREFER THE BOFFFF ?

Spawning occurs in the vicinity of Reunion Island Histological analyses Transverse section of a an early developing ovary stage Transverse section of a a ripe ovary in hydratation Stages 1 Immature 2 3 4 5 6 developing maturing ripening Spawning Spent or resting Maturity scale for females undeveloped Ovocyte diameters Distribution