Abstract:
Abstract: The present study was carried out to understand the occurrence of
maturity stages of double spotted queen fish Scomberoides lysan in the waters
around Jaffna Peninsula. These are economically important food fishes
particularly used for dry fish production in Sri Lanka and also used in sport
fishing. The knowledge on the reproductive biology by identifying the life
stages in relation to the area of occurrence could be the most important
parameter in the management of that species. A total number of 1072 weekly
random samples were collected from the commercial catches at Point Pedro,
Delft, Paasaiyoor, Kurunagar, Ponnalai and Karainagar during January 2010
to December 2011. Microscopic staging system used in the histological
analysis of S. lysan ovary expressed seven ovarian stages such as chromatin
nucleolus stage (I), perinucleolus stage (II), cortical alveolar stage (III), yolk
globule stage (IV), previtellogenic stage (V), migratory nucleus stage (VI),
and post ovulatory follicular stage (VII); and the developmental stage
categorized as immature (I & II), maturing (III), mature (IV & V), spawning
(VI & VII) and spent/resting stage (I & VII), macroscopically. Among all
sampling sites Paasaiyoor (100%), Ponnalai (100%), and Kurunagar (90%)
were dominated by immature stages. Maturing stages of females found in
Kurunagar, Karainagar, Point Pedro and Delft. Mature stages of females only
found in Point Pedro and Delft. Spawning stages of females found only in
Point Pedro and Delft. Resting stage of few females was recorded in Point
Pedro area. S. lysan, male and female less than 40cm in total length were
available only in the Jaffna lagoon. Fish with greater lengths (>50 cm in Total
length) were available only in Point Pedro and Delft region. These results
express that the lagoon area are distributed only by immature and maturing
stages meanwhile matured and spawning stages occurs in the open sea
including Delft, Karainagar and Point Pedro. The knowledge gained from the
present study would be a fundamental addition to ensure the sustainable
fishery.
