Freire, T. Reproductive biology of Syngnathus typhle, Linnaeus 1758 (Pisces, Syngnathidae) from the Ria Formosa.

The current study presents data on the reproductive biology of Syngnathus typhle (L.) in the Ria Formosa lagoon system. Specimens were collected in Ria Formosa during the “Recruitment of Sea Breams (Sparidae) and other commercially important species in the Algarve (southern Portugal)” project EU-DGXIV-99/061, with four different fishing gears: beach seines 25m and 50m, beam trawl and Riley’s pushnet. Samples were taken, monthly, from April 2001 to April 2002. A total of 845 S. typhle were sampled of which, 327 were immature, 375 females and 143 males. The sex ratio was biased 0,38:1 (M/F) towards females. The gonads of each specimen were classified in three macroscopic maturation states, revealing the first maturation size for separate sexes to be 15,36 and 12,53 cm for males and females, respectively and 12,30 cm for the whole sample. The monthly evolution of the gonad-somatic index was analysed by sex and total length of individuals. This evolution was compared with seawater temperature, hepato-somatic index and frequency of brooding males. A long reproductive season starts in February and ends in October. Was found with two periods of major reproductive activity, June to July and between September and October. No brooding males were found from November to January. In this season (resting period), 21 males with a developing brood pouch and a large number of immature individuals were caught. Of the 143 males, 93 had brood pouch content, in which 35 had eggs and 58 had embryos. Embryos were classified in macroscopic developing stages according to the kind of brood pouch content. Absolute and relative marsupial fecundity was 64,75 (±47,69 SD) embryos/brood male and 3,033 (±1,87 SD) embryos/cm of brood male respectively. A relationship between embryos size and stage of development was verified. Brood pouch size and total size were also found to be related and also to fecundity.