Kidwai, Samina, and Shahid Amjad

National Institute of Oceanography, ST 47, Block 1 Clifton, Karachi-75600, Pakistan, Tel: (9221)-9251172-73, Fax: (9221)-9251179, E-mail: niopk@cubexs.net.pk and skidwai@cyber.net.pk

Cephalopod para-larvae in the northwest Arabian Sea- abundance and distribution in relation to monsoonal variability

The pelagic cephalopod para-larvae were part of the zooplankton samples that were collected during the five NASEER (North Arabian Sea Environment and Ecosystem Research) cruises, carried out between 1992 and 1994. Two cruises were during the northeast monsoon, two in the pre-southwest and one during the southwest monsoon period. The eighteen biological sampling stations (except Station 4) were beyond the 200 m depth contour, covering the area near the Pakistan shelf, the deeper Arabian Sea, over the Murray Ridge and up to Oman (3 cruises). The preliminary results showed that the three families, Enoploteuthidae, Caranchiidae and the Ommastrephidae were the most dominant in the area. The highest number of positive hauls were reported during the northeast monsoon period (cruises N1 and N5). Although the cephalopod para-larvae numbers were very low at some stations to estimate the abundance per m³, the highest number (118), mean 62.86 (±26.36) were reported during N5 (northeast monsoon). The Ommastrephid (Sthenoteuthis oualenisis) was the most common of all the species during all the five cruises, with the highest percentage (~93%) during N5 (northeast monsoon). The general size ranged between mantle length (ML) 10.74 mm to <1.0 mm. The overall abundance and distribution variability during the study period has also been discussed.