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, Pakistan

Diet composition and feeding habits of Mugil cephalus (Family Mugilidae) from the

Korangi-Phitti Creek System

Introduction

• Mugil cephalus (Family Mugilidae) marine coastal, found in tropical and temperate waters.

• Their juveniles and adults are euryhaline and eurythermal in nature and enter into the estuaries and rivers for feeding.

• It is an economic important sp., in Pak. total catch decreased from 22,485 Metric Tons in 1993 to 12,336 metric tons in 1999 (Fisheries statistics, 2002)

OBJECTIVES

• To evaluate the feeding habits of Mugil cephalus within different creek structures (small and medium);

• To evaluate the diet changes in the monsoonal season;

• To analyze the importance of creeks as feeding area which is considered in relation to the sources of food available in the habitat that support the nourishment and growth of juvenile fishes.

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 cm stretch mesh size monofilament gill nets.

HABITAT DATA COLLECTION:• As a general index of temporal changes in environmental

conditions in our study area, water temperature, air temperature, salinity, dissolved oxygen, and tidal stage and depth were recorded at each site on each sampling date. 

ANALYSIS:• Stomach-fullness index (SFI)=wet mass of stomach

content(g) / body wt. of fish(g)x100;• State of digestion; volume of food contained in stomach; • Sub-sample of food contents were examined under

microscope;• Prey items were identified to the genus or species level,

counted.

RESULTS

Total fish caught= 88

Season . Creek Structure

NEM APT SWM OCT Small Medium

N=45 N=0 N=31 N=12 N=12 N=7

Tide (m)Mean 2.20 2.52 2.10 1.96 2.56 2.45

±SE 0.10 0.18 0.08 0.12 0.05 0.19

Depth (m)Mean 6.13 3.24 6.01 9.64 5.49 6.93

±SE 0.46 0.30 0.42 1.26 0.28 0.92

Atmospheric Temperature 0CMean 28.02 32.53 31.70 33.47 30.92 31.25

±SE 0.25 0.20 0.19 0.24 0.28 0.59

Water Temperature 0CMean 24.16 29.53 30.22 30.25 28.22 27.30

±SE 0.28 0.18 0.14 0.14 0.30 0.89

Salinity (ppt)Mean 39.36 40.92 38.14 38.74 38.16 39.85

±SE 0.16 0.62 0.20 0.36 0.23 0.38

DO (mg/l)Mean 5.71 3.72 5.34 5.15 5.05 6.14

±SE 0.28 0.06 0.15 0.30 0.22 0.44

05

10152025

303540

4550

Empty 25% 50% 75% 100%

Stomach Fullness

Per

cen

tag

e

0

1

2

3

4

5

6

7

8

230-258 259-287 288-316 317-345 346-374 375-403

Size Class (mm)

Per

cen

tag

e

0

5

10

15

20

25

0.05 0.1 0.25 0.3 0.5 0.6 0.8

Stomach Fullness Index (SFI)

Per

cen

tag

e

Jan.00

Feb. Mar. Apr. May June Jul. Aug. Sep. Oct. Nov. Dec. Jan01

2 11 1 15 2 2 12 26 13 4

N=16

Food Items present in the stomachs of Mugil cephalus

Cynophyta: Anabaena, Chrooococcus, Merismopedia, Oscillatoria etc.Chlorophyta: Ulothrix, Westellopsis, Hormidium, Closterium spp. Bacillariophyta: Amphora, Cymbella, Diploneis, Cocconies, Navicula Foraminifera: Discorbis, Foraminifera speciesCnidarians: Corals Platyhelminthes: Cestod parasiteAnnelida: Trocophore larva, Polychaete wormsNematoda: Trematode parasite, Nereid worms Echinodermata: Holothurians and BipinnariaMolluscs: Velliger, Broken shell piecesBryozoa: Cyphonautes larva Arthropoda: Cypis, Nauplie, Zoea, Megalopa, Mysis, Copepods etc. Urochordata: Tunicate larva, ProrocentrumCiliataea: Vorticella sp.Chaetognatha: Fish Larvae:

Percentage of Prey Item Groups in the Stomachs of Mugil cephalis

Platyhelminthes, 0.133

Annelida, 2.35

Cnidaria, 0.016

Foraminifera, 5.24

Nematoda , 0.89

Echinodermata, 3.17

Urochordata, 0.04

Bryozoa, 0.76

Molluscs, 12.1

Bacillariophyta 25.09

Cynophyta, 4.023

Chlorophyta, 4.388

Ciliatae, 0.0083

Chaetognatha, 0.008312

Fish larva, 0.0083

Arthropoda 43.73

N=16

N.gracilis

E.sorex

A.brevipes

D.ovalis

P.spenceri

N. rotaeana

1. Cynophyta; 2. Chlorophyta; 3. Bacillariophyta; 4. Foraminifera; 5. Cnidaria; 6. Platyhelminthes; 7. Annelida; 8. Nematoda; 9. Echinodermata; 10. Molluscs; 11. Bryozoa; 12. Arthropoda; 13. Urochordata; 14. Ciliatae; 15. Chaetognatha; 16. Fish larva.

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Groups

Per

cen

tag

ePort Qasim (N=7)

Ganglaro Creek (N=12)

N.filiformis

P.kernari

Merismopedia sp.

Surirella sp.

Cymbella

Mugil cephalus

1. Cynophyta; 2. Chlorophyta; 3. Bacillariophyta; 4. Foraminifera; 5. Cnidaria; 6. Platyhelminthes; 7. Annelida; 8. Nematoda; 9. Echinodermata; 10. Molluscs; 11. Bryozoa; 12. Arthropoda; 13. Urochordata; 14. Ciliatae; 15. Chaetognatha; 16. Fish larva.

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Groups

Per

cent

age

NEM (N=8)

SWM (N=7)

OCT (N=3)

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 of

microscopic algae, plant materials, zooplanktons, annelids, crustacean

parts, and miscellaneous items.

Diet contained Cnidarians, chaetognaths & fish larvae only at

Ganglaro Creek while ciliatae at PQ;

Cnidarians were found in SWM and Oct., fish larvae only in Oct.;

Ciliate & chaetognathes were found in NEM season, urochordates

found in NEM & Oct.

Coral Prorocentrum

Fish larva

Tunicate larva

Copepod

Comparisons between creeks indicate that the feeding

preferences of M. cephalus in the small (GNG) & medium

(PQ) creeks were consistently fluctuate during the

monsoon seasons.

The diet group most abundant in the small creeks were

Cynophytes, Chlorophyes, bryozoans & molluscs while the

wide creeks diet were characterized by diatoms,

Foraminiferas, Holothurians, Crustaceans.

Seasonal comparisons indicated that the prey items in the gut of

M. cephalus were significantly different during the NEM, SWM and

October transitional seasons.

The prey groups in the gut of M. cephalus were

highest during the NEM & Oct. transitional season,

whereas lowest groups were found in the SWM

season and was characterized by crustaceans.

The diversity of prey items found in the stomachs of

M. cephalus suggest that mangroves found in the

Korangi Creek System provide a nutritionally rich

environment for the existence of marine fauna and

flora. The mangroves soil creates an ideal habitat for

the variety of organisms and play a significant role in

the food chain.

Acknowledgements: The study was supported by the Pakistan Science Foundation Islamabad project number S-KU/BIO(319).

Data on the economic value of the mangrove-based fisheries in the Indus Delta area are not available. However, since employment and income in the region depends heavily on this resource, its contribution to the local economy is significant.

Despite the importance of the fisheries within the region, little baseline biological data (i.e., community composition and seasonal use) are available for many fish species from these waters.

The results of the present study can be used to promote effective management and conservation of the fisheries in the region.