Increasing trends in capture of fish juveniles and sub-adults: A red signal for fishery resources

Abstract

In this paper, we have figured out tendency of sweeping juveniles and sub-adults of commercially important fish stocks in northern Arabian Seacoast of Pakistan. The specimens were collected from Zero point Badin (ZPB), Hyderi fish jetty (HFJ), Clifton Karachi (CFK) and Karachi Fish Harbour (KFH) from August 2014 to March 2015. These fishes mainly caught with purse seines, gill nets, pelagic and demersal trawls and beach seines. An average 40t/day undersize catch (trash) have been recorded from ten fish landing sites in Karachi with an average 15t/day have been landed at KFH solely. Some 562 individuals belonging to the (38) families and (67) species were procured. The composition of fish families by weight from the KFH was categorically Platycephalidae 20%, Engraulidae and plotosidae 12% respectively; from HFJ, family Sciaenidae comprises of 26%, Dasyatidae 23% and Muraenesocidae 13%; from ZPB, Gobiidae 31%, Soleidae 14% and Polynemidae and Sciaenidae 12%; and from CFK, Clupeidae 49%, Penaeidae 28% and Trichiuridae 10%. The diversity index H' was estimated for four sampling sites the highest diversity (3.29) and the lowest (1.93) for KFH and CFK respectively, whereas highest species richness R=8.49 from HFJ followed by KFH, R=5.24 and the lowest R=2.28 from CFK. Comparing similarity index KFH and HFJ shared highest number of similar species. It is assumed from the consistent landing of juvenile and sub-adults of various valuable fish stocks is clear indication of population deterioration and seems appropriate monitoring and mesh size regulation are beyond the priorities of fishers and mangers.