Sadaf Fatima*, Zakia Khatoon**, S. Makhdoom Hussain***and Razia Sultana***Centre of Excellence in Marine Biology, University of Karachi**Pakistan Council of Scientific and Industrial Research, Labs. Complex, Karachi*** NAPHIS, Ministry of Food, Agriculture and Livestock, Islamabad, PakistanDiet composition and feeding habits ofMugil cephalus (Family Mugilidae) from theKorangi-Phitti Creek System
Introduction• Mugil cephalus (Family Mugilidae)marine coastal, found in tropical andtemperate waters.• Their juveniles and adults areeuryhaline and eurythermal in natureand enter into the estuaries and riversfor feeding.• It is an economic important sp., in Pak. totalcatch decreased from 22,485 Metric Tons in1993 to 12,336 metric tons in 1999 (Fisheriesstatistics, 2002)
OBJECTIVES• To evaluate the feeding habits of Mugil cephaluswithin different creek structures (small andmedium);• To evaluate the diet changes in the monsoonalseason;• To analyze the importance of creeks as feeding areawhich is considered in relation to the sourcesof food available in the habitat that supportthe nourishment and growth of juvenilefishes.
FISH COLLECTION:• Mugil cephalus was collected from 19 stations (GNG= 12,PQ= 7) during the Jan. 2000-Jan.2001, with 5.7 and 3.8 cmstretch mesh size monofilament gill nets.HABITAT DATA COLLECTION:• As a general index of temporal changes in environmentalconditions in our study area, water temperature, airtemperature, salinity, dissolved oxygen, and tidal stage anddepth were recorded at each site on each sampling date.ANALYSIS:• Stomach-fullness index (SFI)=wet mass of stomachcontent(g) / body wt. of fish(g)x100;• State of digestion; volume of food contained in stomach;• Sub-sample of food contents were examined undermicroscope;• Prey items were identified to the genus or species level,counted.
Percentage of Prey Item Groups in the Stomachs of Mugil cephalisPlatyhelminthes,0.133Annelida, 2.35Cnidaria, 0.016Foraminifera,5.24Nematoda ,0.89Echinodermata,3.17Urochordata,0.04Bryozoa, 0.76Molluscs, 12.1Bacillariophyta25.09Cynophyta,4.023Chlorophyta,4.388Ciliatae,0.0083Chaetognatha,0.008312Fish larva,0.0083Arthropoda 43.73N=16N.gracilisE.sorexA.brevipesD.ovalisP.spenceriN. rotaeana
SUMMARY Mugil cephalus were not found during the April trans. Period,when the salinity was higher & DO was lower.The analysis of the gut contents showed different percentages ofmicroscopic algae, plant materials, zooplanktons, annelids, crustaceanparts, and miscellaneous items.Diet contained Cnidarians, chaetognaths & fish larvae only atGanglaro Creek while ciliatae at PQ;Cnidarians were found in SWM and Oct., fish larvae only in Oct.;Ciliate & chaetognathes were found in NEM season, urochordatesfound in NEM & Oct.Coral ProrocentrumFish larvaTunicatelarvaCopepod
Comparisons between creeks indicate that the feedingpreferences of M. cephalus in the small (GNG) & medium(PQ) creeks were consistently fluctuate during themonsoon seasons. The diet group most abundant in the small creeks wereCynophytes, Chlorophyes, bryozoans & molluscs while thewide creeks diet were characterized by diatoms,Foraminiferas, Holothurians, Crustaceans.Seasonal comparisons indicated that the prey items in the gut ofM. cephalus were significantly different during the NEM, SWM andOctober transitional seasons.
The prey groups in the gut of M. cephalus werehighest during the NEM & Oct. transitional season,whereas lowest groups were found in the SWMseason and was characterized by crustaceans.The diversity of prey items found in the stomachs ofM. cephalus suggest that mangroves found in theKorangi Creek System provide a nutritionally richenvironment for the existence of marine fauna andflora. The mangroves soil creates an ideal habitat forthe variety of organisms and play a significant role inthe food chain.
Data on the economic value of the mangrove-based fisheries in theIndus Delta area are not available. However, since employment andincome in the region depends heavily on this resource, itscontribution to the local economy is significant.Despite the importance of the fisheries within the region, littlebaseline biological data (i.e., community composition and seasonaluse) are available for many fish species from these waters.The results of the present study can be used to promote effectivemanagement and conservation of the fisheries in the region.