40

CHAPTER – II

FOOD AND FEEDING HABITS

41

INTRODUCTION

Nutrition is one of the essential requisites of living beings in nature for continuance

of their vital needs viz., growth and reproduction for survival and thus maintain

their kind. Fishes directly depend upon their surrounding aquatic environment for

their food requirements and are highly adopted in their food and feeding habits,

utilizing most of the readily available food.

Studies on the food and feeding habits, an important aspect in the biology of fishes,

have shown that the requirements at different stages in their life cycle differ with

space and time (Hardy 1936). The importance of the knowledge of food and feeding

habits of a fish in understanding its biology has been well established. Sometimes

the rate of feeding has a bearing on the spawning of the fish. The nature of food

composition of a fish species will also throw light on the possible habitats it

frequents.

The material food of fishes was classified by Schaperclaus (1933) into 3 groups i.e.,

main food, occasional food and emergency food and by Nikolsky (1963) into 4

groups i.e., basic food, secondary food, incidental food and obligatory food based

on the feeding habits of fish. Nikolsky (1963) categorized the fishes into Euryphagic

(feeding on a variety of food), Stenophagic (feeding on a few selected foods) and

Monophagic (feeding on a single type of food). Another Classification of fishes is

Predators (feeding on other animals), Grazers (feed on small organisms by

browsing), Suckers (suck the food containing material) and Parasites (which absorb

the body fluids from the hosts).

The magnitude of fish population in a region is a function of its food potentialities.

Food enriches the biochemical components of fishes. The seasonal and diurnal

abundance of different food organisms may influence the movements and migration

42

of fishes. Hence it is very essential to gain an insight into the relationship between

the fishes and their food organisms for prediction and exploitation of fish resources.

Mookherjii et al., (1964) classified the feeding habits of some fishes on the basis of

the presence of maximum percentage of the type of food in the guts of the fish. Das

and Moitra (1963) classified fishes into herbivores which feed on plant materials,

carnivores which feed on animal materials and omnivores which feed on one or

more groups of organisms, i.e., plankton, nekton or benthos and/or detritus.

Ganapati and Chacko (1950) grouped several fishes of cultivable importance into

surface feeders, column feeders and bottom feeders. There are also terms like

Piscivorous – feeding mainly on fish, Carnivorous – feeding mainly on crustaceans,

Planktivorous – feeding on plankton, Detritivorous – feeding on detritus and

Cannibalistic – feeding on their own kind.

Hynes (1950) and Pillay (1952) have reviewed the various methods employed in the

study of the food of fishes. Rounsefell and Everhart (1953) have described these

different methods in detail. Studies on the food and feeding habits of fishes have

been reported by several researchers. Note worthy among them are of Job (1940),

Vijayaraghavan (1953, 55), Bal and Joshi (1956), Ganapathi, Rao and Sreenivasa

Rao (1957, 1959), Talwar, (1962a, 1962), Balan (1963), Srinivasa Rao (1964a,

1964b), George et al (1968), Mojumdar (1969), Krishna Moorthi (1971), Mojumdar

and Das (1979) Manikayala Rao (1981), Venkateswara Rao(1992), Satti

Reddy(1992), Sivani (1994), Rao et al (1998), Padmaja (1998), Sankara Rao (2001),

Durga Prasad (2002), Appala Naidu (2003), Ramana (2007), Shanti Prabha et al..

(2008), Sobha Rani (2010) etc.

The knowledge of the food and feeding habits of a fish helps in finding out the

distribution of a fish population and a thorough Survey of literature indicates that

such knowledge is highly essential for successful management of a fishery and such

studies are undoubtedly important in any fisheries research program.

43

The Mullidae (goatfishes) are widely distributed in many temperate, subtropical and

tropical marine waters. Majority of the species (55) are found over sand and around

reefs at a depth of 540 m (Munro 1976; Hutchins and Swainston, 1986; Kuiter,

1994). Co-occurring species sometimes partition their environment on the basis of

water depth, degree of exposure and substratum type. (Munro, 1976; Golani Gali,

1991; Golani, 1994; Mc Cornick, 1995).

Most of the fifty or more families of percoid fishes are separated from one another

by minor structural features (Regan, 1913). The goatfishes differ drastically from

the general pattern. They are equipped with two long whiskers (barbels) that extend

from the chin. These whiskers contain chemosensory organs and can detect even

extremely well camouflaged and carefully hidden prey in the sand (Munro, 1976;

Golani & Gali, 1991, 1994; Mc Cornick 1995).

The goat fish will use its whiskers to probe the sand in search of small fish and

various types of small invertebrates, such as crustaceans, molluscs and worms. All

species of goatfish are benthic carnivores (Hobso, 1974; Caragistsou & Tsimendi,

1982 a, b; Wahheh & Ajiad, 1985, Golani & Gali 1991; Vassipoulou &

Papaconstantnou 1993; Golani, 1994).

The goatfishes include about 50 bottom-foraging fish species, following the

foraging mode commonly recorded for reef fishes during heterospecific feeding

associations (Ormond, 1980; Stand, 1988; Lukoschek & Mc cormick, 2000; Sazima

et al., 2005). These fish play a key role in the formation of multispecies foraging

associations as nuclear species that are followed by many other species. (Franz

Uiblein, 2007). Such foraging associations are wide spread and recorded for several

fishes and other marine animal taxa and geographic sites (Diamant & Shpigel, 1985;

Lukoschek & Mc cormick, 2000; Gibran, 2002; Sazima et al, 2005;

Papaconstantnou 1993; Golani, 1994) etc. Studies on some aspects of food and

feeding habits of goatfishes have been reported from various regions of the World.

To mention few of them are Ramaswamy (1955), Russel (1983), Boraey and

44

Soliman (1984 and 1987), Wahbeh and Ajian (1985), Vassilopoulou and

Papaconstatinou (1992), Reuben et al (1994) Torcu (1995); Kaya et al (1999);

Jayaramaiah et al (1996), Ameerhansa, K.M.S. & K. Narayana Rao (1997);

Labropoulou et al (1997); Ali and Gopalakrishnan (1998); Bhargava and Somvanshi

(1998); Ismen (2005 and 2006) ; Shanti Prabha et al. (2008), Sobha Rani (2010) etc.

Present investigation has been aimed at the importance of the food and feeding

habits of two species of goat fishes viz. Upeneus vittatus and Upeneus moluccensis

from the Coastal waters of Visakhapatnam, in understanding the growth rate,

gonadal maturity and other metabolic activities.

45

MATERIAL AND METHODS

Samples for the present study were collected at monthly intervals from the

mechanized boats that are operated at the Visakhapatnam fishing Harbour. The

study is based on examination of specimens collected during the study period i.e.,

May 2006 to April 2008. Out of 1505 specimens 753 were Upeneus vittatus and 752

were Upeneus moluccensis.

The data on total length, weight, sex and stage of sexual maturity of each fish were

recorded immediately after collection of the sample. The stomachs were then

carefully taken out, fixed in 5% formalin, dried between sheets of filter paper and

slit open with a pair of scissors. The following methods were adopted for assessing

the food and feeding habits of the fish.

Points Method: The degree of apparent fullness of stomachs was determined and

points were assigned as 1.25 for gorged stomach; 1.0 for full stomach; 0.75 for ¾

full stomach; 0.5 for ½ full stomach; 0.25 for ¼ full stomach; 0.1 for traces and 0

for empty stomach (Bapat & Bal, 1950).The fish was considered as active feeder,

when the stomach was gorged, full & ¾ full; moderate feeder when ½ full and

passive feeder when ¼ full or with traces.

Index of Preponderance: The grading of food elements was calculated by the

methods of Index of preponderance of Natarajan & Jhingran (1961). This method

is a combination of occurrence (qualitative method) and volume (quantitative

method) of food contents for grading the different food items which can be

expressed as

Where Ii represents the index of preponderance

Vi represents the percentage of volume of particular food

46

Oi represents the percentage of occurrence of particular food.

Volumetric method: Volumetric analysis (Pillay, 1952) was carried out by

displacement of water in a measuring jar. The volume of each food item was

expressed as percentage of the total volume of the entire gut contents.

Occurrence method: In this method, the number of guts containing a specific food

item is expressed as a percentage of total number of guts examined (Hynes, 1950).

Gastro – Somatic Index: - This method is useful for estimating the feeding intensity

of fishes (Desai, 1970). The stomach contents were weighed to the nearest 0.1 g to

determine the gastro somatic index which can be calculated as follows

GSI =

47

RESULTS

During the entire period of study, a total of 753 guts of Upeneus vittatus and 752

guts of Upeneus moluccensis were examined. The index of preponderance of

various food items and percentage of feeding intensity of the fishes Upeneus vittatus

and Upeneus moluccensis from the study area are presented in tables 2.1 & 2.3 and

2.2 & 2.4 respectively. The percentage composition of the food items of both fish is

represented as pie diagrams (Fig: 8 c to Fig: 19 d).

Food composition of Upeneus vittatus: The gut contents of this fish mainly

composed of crustaceans, molluscs, fish larvae, polycheats along with digested

material and semi digested material. Crustaceans represented mainly by shrimps

besides some prawns and crabs. Some of the fish remains were identified as of

teleostean fish, mainly of megalaspis species, but most of the teleostean fish remains

could not be identified since they were found in advanced stages of digestion with

only skeletal remains. Molluscs were identified as bivalve mollusks.

Food composition of Upeneus moluccensis: The gut contents of this fish mainly

consisted of crustaceans, molluscs, teleostean fish, polycheats and bivalves besides

mud particles. Apart from all these organisms digested matter and semi digested

matters was also encountered in different quantities in the gut content.

Index of preponderance: In the fishes crustaceans formed the main constituent of the

food items followed by fishes. From the index of preponderance it can be

understood that next to teleost fishes, the fishes prefer molluscs and polychaets

according to the order of their abundance.

In Upeneus vittatus, crustaceans frequency ranged from 9.8-63.2% where as in

Upeneus moluccensis they ranged from 3.8-75.4. Teleostean fish frequency ranged

from 4.5 -10.42% in U. vittatus and 3.6-16.8% in U. moluccensis, the percentage

48

index of preponderance of molluscs ranged from 17.8-18.9 % in U. vittatus and

from 7.3-10.2 in U. moluccensis, Polycheats showed a frequency range of 19.2-

24.3% in Upeneus vittatus and 2.2-5.2% in Upeneus moluccensis. Along with this

material digested food and semi-digested food (i.e. unidentified food) was also

observed in both the species, which ranged from 1.3 -58.0% and 9.42-83.2% in

Upeneus vittatus and 9.2-48.1% and 6.6-58.1% in Upeneus moluccensis.

Monthly feeding intensity based on point‟s method & gastro somatic index: The

average values of the amount of feeding based on points method varied from 0.38 to

2.78 in Upeneus vittatus, where as it varied from 0.4 to 1.93 in Upeneus

moluccensis. The feeding intensity in Upeneus vittatus was high in the months of

June, September and October and in U. moluccensis during September, October.

The gastro-somatic index in various months varied from 2.674 to 19.27 in U.

vittatus. The highest index was recorded in the month of June, 2006 while the least

was recorded in the month of May 2006. In U. moluccensis the gastro somatic index

varied 2.83 to 11.57, with the highest index in the month of September 2007, and

the least in the month of August 2006 (Tables 2.3 and 2.4).

49

DISCUSSION

The present investigation revealed that both Upeneus vittatus and Upeneus

moluccensis are carnivorous species feeding mainly on crustaceans and teleostean

fishes and occasionally on molluscs. The various components of the food spectrum

indicate that these species mainly feed on benthic and sub-benthic organisms

detected by chemoreceptor rich barbels present on the chin. Goat fish feed on small

benthic crustaceans, worms, mollusks and small fish (Vassilopoulo and

Papacostantinou 1992, Labropoluo et al 1997). It is apparent that goat fish feeds

mainly on invertebrates particularly crustaceans.

The high percentage of occurrence of the mud and sand particles in the guts of both

the species along with major food items confirm that they are bottom feeders. A

similar conclusion was drawn by Thomas (1969). The composition of the diet

indicated that they feed on crustaceans and teleosts. Molluscs also contributed to the

diet during some of the months of the study period (Tables 2.1 and 2.2)

The percentage indices of emptiness and fullness of stomachs are very important to

assess the feeding intensity. Most mullids feed primarily on polychaets and

crustaceans. However considerable differences have been observed in the diets of

different species (Hobson 1974). Pietelietal (1998), Randall (1967) reported that

mullids feed primarily over muddy sandy bottoms upon surface or sub-surface

dwelling invertebrates. The long barbels are swept over sediments and are

presumably receptive to contact with prey animals. He also observed that the

stomach contents of Parupenus maculates consisted of crabs and shrimps in higher

percentages and polycheats relatively in low percentage where as in the case of

Mullus martinius, crab larvae, pelecypods, shrimps, shrimp larvae and ophiuroids

were observed.

50

Russel (1983) studied on food and feeding habits of rocky reef fish of north-eastern

New Zealand and reported that U. lineatus feeds predominantly on small

crustaceans. Wahbeh and Anjain (1985) observed that the most important prey of P.

barberinus was crustaceans and also the bivalves which became an increasingly

important component of the diet of the large size classes of mulled Parpeneus

barberinus from guts of Agaba.

Jayaramaiah et al., (1996) reported that Upeneus vittatus from Mangalore coast is

carnivorous, feeding mainly on prawns and teleosts. In our present study on the

same species from Visakhapatnam, it is observed that it mainly feeds on

crustaceans, molluscs and teleosts. In both the coasts fry of megalaspis (teleosts)

were found in Upeneus vittatus. Leiognathus sp. and Platycephalus sp. was

predominant from Mangalore coast.

During the course of the investigation a large number of fishes were found with

empty stomachs. Such occurrence of empty stomachs in high percentage has been

recorded earlier (Kagwada, 1974) for many species of fishes. The frequent

occurrence of empty stomachs or stomachs with little contents might be dependent

on the ratio between the size of the fish and, size of the prey as cited by Allen

(1935) or on the calorific values of the diet as explained by Longhrust (1957). The

occurrence of empty stomachs Upeneus vittatus and Upeneus moluccensis do not

show any relation either to season or to the size of the fish.

However the feeding intensity was different in between the two species in different

months. Maximum intensity of feeding was observed in the months of May & June

in Upeneus vittatus while in case of Upeneus moluccensis, the maximum intensity

of feeding was observed in the months of September and October. It is quite

interesting to note that it coincides with their breeding seasons that follow the

maximum feeding intensity. U. vittatus breeds a little early compared to that of U.

moluccensis, thus showing the difference in between them. The difference in

51

maturity of the individual of the species is perhaps the reason for the difference in

feeding intensity observed in the different months (Tables 2.3 and 2.4)

As seen from the results, it could be inferred that both the species, that is Upeneus

vittatus and Upeneus moluccensis from coastal waters of Visakhapatnam mainly

feed on crustaceans, teleostean fishes and molluscs. The percentage of occurrence of

different food items in the diet shows that these fishes select their food from the

bottom living organisms and the first preferable food item was crustaceans (shrimp).

Thus, the present investigation revealed that both the species of Upeneus are

demersal carnivores, whose diet is mainly composed of crustaceans (shrimps &

crabs), teleostean fishes and bivalve molluscs.

52

Fig: 8a Monthly variations in the Gastro-Somatic index of Upeneus vittatus

Fig: 8b Monthly variations in the Gastro-Somatic index of Upeneus moluccensis

53

Table 2.1

Percentage of occurrences, percentage of volume and index of preponderance of different food items of Upeneus vittatus at

study area in different months.

Shrimps Molluscs Teleosts Polycheates Digested food Unidentified food items

Months %V1 %O1 I.P. %V1 %O1 I.P. %V1 %O1 I.P. %V1 %O1 I.P. %V1 %O1 I.P. %V1 %O1 I.P.

May-06 32.1 20.2 23 N N N N N N N N N 9.8 11.3 14.2 9.8 11.3 14.2

June 61.1 65.3 54 N N N 1.2 11.1 4.5 23.6 11.2 24.31 23.6 11.2 1.2 23.6 11.2 1.2

July 71.2 68.2 80.1 N N N 1.3 10.1 4.6 N N N 10.2 15.7 15.3 10.2 15.7 15.3

Aug 30.5 21.5 15.3 N N N N N N N N N 1.1 7.4 2.4 1.1 7.4 2.4

Sep 54.34 53.33 51.2 N N N 20.1 20.1 11.1 N N N 19.9 20 16.6 19.9 20 16.6

Oct 60 60 62.3 N N N 10 9.9 9.42 N N N 20 20.2 18.8 20 20.2 18.8

Nov 42.4 44.4 38.2 12.11 11.1 18.9 N N N 24.2 22.22 21.2 N N N N N N

Dec 36.3 33.3 34.6 N N N N N N N N N 9.09 16.6 15.2 9.09 16.6 15.2

Jan-07 10.6 16.6 10 N N N N N N N N N 54 50 58 54 50 58

Feb 19.3 18.6 9.8 N N N N N N N N N 25.1 32.3 28.1 25.1 32.3 28.1

March 18.5 28.6 21.9 N N N N N N N N N 26.9 32.9 21.9 26.9 32.9 21.9

April 12.4 13.3 9.2 N N N N N N N N N 29.4 22.1 19.6 29.4 22.1 19.6

May 31.1 20.3 28 N N N N N N N N N 16.3 14.3 12 16.3 14.3 12

June 59.2 66.2 57.2 N N N 1.2 11.2 4.5 23.6 11.3 23.3 23.6 11.2 1.3 23.6 11.2 1.3

July 72.2 69.2 81.1 N N N 1.4 10.2 4 N N N 10.3 15.7 15.1 10.3 15.7 15.1

Aug 31.6 22.6 13.2 N N N N N N N N N 1.2 7.3 4.4 1.2 7.3 4.4

Sep 53.3 54.2 52.1 N N N 20.2 19 13.1 N N N 19.8 20.1 16.6 19.8 20.1 16.6

Oct 61.1 61.1 53.2 N N N 10.1 9.8 10.42 N N N 21.1 20.1 27 21.1 20.1 27

Nov 42.3 45.5 39.3 11.2 12.1 17.8 N N N 24.22 22.3 19.21 N N N N N N

Dec 37.1 32.3 35.2 N N N N N N N N N 9.9 7.6 15.6 9.9 7.6 15.6

Jan-08 9.5 17.7 9.6 N N N N N N N N N 54.1 50 58 54.1 50 58

Feb 20.2 18.6 10.1 N N N N N N N N N 25.1 32.3 27.8 25.1 32.3 27.8

March 17.7 29.1 22.8 N N N N N N N N N 26.9 32.9 18 26.9 32.9 18

April 13.4 12.9 10.3 N N N N N N N N N 29.4 22.1 18.5 29.4 22.1 18.5

% V1 – Percentage of volume; %O1 – Percentage of occurrence; I.P. – Index of Perponderance; N - NIL

54

Table 2.2

Percentage of occurrences, percentage of volume and index of preponderance of different food items of Upeneus moluccensis

at study area in different months.

Shrimps Molluscs Teleosts Polycheates Digested food Unidentified food items

%V1 %O1 I.P. %V1 %O1 I.P. %V1 %O1 I.P. %V1 %O1 I.P. %V1 %O1 I.P. %V1 %O1 I.P.

May-06 38.1 18.3 28.7 N N N N N N N N N 9.6 25.3 15.2 52.3 56.4 56.1

June 66.3 71.2 65.3 N N N 10.3 3.1 6.5 N N N 19.5 9.6 22.6 3.9 16.1 5.6

July 69.2 72.3 66.3 N N N 11.1 4.2 5.5 N N N 18.7 9.4 21.6 5.2 17.1 6.6

Aug 9.8 12.5 3.8 N N N N N N N N N 45.1 43.7 48.1 45 43.8 48.1

Sep 64.2 50 71.1 N N N 14.3 5.5 10.2 N N N 12.3 6.3 9.2 11.6 9.7 9.8

Oct 65.5 62.5 66.3 N N N N N N N N N N N N 34.5 37.5 33.7

Nov 31.1 27.2 28.6 N N N 16.7 9.09 16.8 N N N N N N 52.2 63.6 54.6

Dec 39.5 33.3 34.5 14.3 5.5 10.2 10.3 3.1 6.5 8.8 11.5 4.7 22.3 21.2 24.2 30.1 26.4 20

Jan-07 32.3 29.2 25.9 17.2 14.3 7.3 19.2 14.5 9.5 N N N N N N 71.3 69.4 57.3

Feb 29.3 26.2 20.2 N N N N N N N N N 45.4 38.2 40.3 41.2 36.2 39

March 22.4 20.1 23.2 N N N 4.5 2.2 3.6 3.4 1.3 2.2 10.9 11.6 13.3 37.2 36.4 39.3

April 24.5 22.3 25.5 N N N 3.7 4.5 5.7 N N N 16.6 15.4 19.3 45.6 43.2 48.2

may 38 18.2 27.7 N N N N N N N N N 9.6 25.4 14.2 52.4 56.2 49.1

June 66.4 71.3 62.3 N N N 10.3 3.1 7.5 N N N 19.5 9.7 23.6 3.9 16 58.1

July 38.9 36.4 47.2 N N N N N N N N N 19.5 17.1 21.2 29.1 28.7 6.6

Aug 9.9 12.6 3.9 N N N N N N N N N 45 43.6 48 45.1 43.8 31.6

Sep 56.7 54.5 74.4 7.2 5.6 9.2 N N N 3.6 2.2 5.21 N N N 8.5 6.4 48.2

Oct 66.6 63.5 66.3 N N N N N N N N N N N N 35.5 38.5 11.3

Nov 31 27.1 28.5 N N N 15.7 8.09 15.8 N N N N N N 53.3 64.6 34.7

Dec 38.6 34.3 36.5 14.3 5.5 10.2 10.3 3.1 6.5 9.8 3.8 3.8 22.3 20.2 23.4 30.1 26.5 55.6

Jan-08 29.2 27.6 28.5 N N N 3.4 2.2 4.6 N N N 16.4 14.6 19.2 41.2 39.4 20.2

Feb 27.2 22.7 25.6 5.9 4.2 7.6 N N N 3.6 1.4 2.2 11.4 7.6 14.2 51.2 47.6 47.8

March 25.7 21.2 22.5 N N N 13.5 12.2 14.9 N N N 14.4 13.2 16.9 46.5 44.2 50.4

April 25.7 24.2 26.5 N N N 4.9 3.4 4.7 N N N 18.1 16.3 22.3 47.5 42.2 45.7

% V1 – Percentage of volume; %O1 – Percentage of occurrence; I.P. – Index of Perponderance; N - NIL

55

Table 2.3 Feeding intensity and Gastro Somatic indices of Upeneus vittatus in different months.

Months

No .of

stomachs

examined

Average

points

assigned

Average

GSI

Gorged

%

Full

%

3/4 full

%

1/2 full

%

1/4 full

%

Empty

%

May-06 30 0.38 2.674 3.33 6.66 10.2 16.6 26.6 36.6

Jun 30 2.78 19.27 6.66 13.3 16.6 23.3 30.1 10.1

Jul 30 1.31 3.716 6.66 10 13.3 20 26.6 23.3

Aug 33 0.56 4.401 3.03 6.06 9.09 18.18 24.2 39.3

Sep 30 1.57 10.931 10 16.6 20 16.6 23.3 13.3

Oct 30 1.43 9.208 6.66 13.3 16.6 20 26.6 16.6

Nov 32 0.64 4.386 6.25 9.37 12.5 18.7 28.1 25

Dec 32 0.58 3.682 NIL 6.25 9.37 15.6 25 37.5

Jan-07 30 0.48 3.311 3.33 6.66 6.66 20 40 23.3

Feb 34 0.5 2.992 2.94 5.88 5.88 11.7 20.5 52.9

Mar 34 0.42 3.321 5.88 8.82 11.7 14.7 23.5 35.2

Apr 30 0.44 2.872 NOL 6.66 10 13.3 30 40

May 30 0.39 2.675 3.33 6.67 10 16.5 26.6 36.6

Jun 30 2.78 19.28 6.66 13.4 16.5 23.3 30 10

July 30 1.32 3.717 6.65 10 13.2 20 26.6 23.3

Aug 33 0.57 4.402 3.03 6.06 9.09 18.18 24.6 39.3

Sep 30 1.58 10.831 9 17.6 19 17.6 23.3 13.3

Oct 30 1.42 9.209 6.66 13.3 16.5 20.1 26.7 16.5

Nov 32 0.63 4.387 6.25 8.37 13.5 19.7 27.1 25

Dec 32 0.59 3.684 N 7.25 8.37 15.6 26 36.5

Jan-08 30 0.47 3.311 3.33 6.66 7.66 19.1 41 22.3

Feb 34 0.51 2.993 2.94 6.88 4.88 12.7 19.5 52.9

Mar 34 0.41 3.323 6.88 7.82 11.7 13.7 24.5 35.2

Apr 30 0.43 2.873 N 6.67 11 12.3 29 41.1

56

Table 2.4-Feeding intensity and Gastro somatic indices of U. moluccensis in different

months.

No of

stomachs

examined

Average

points

assigned

average

GSI

Gorged

%

Full

%

3/4

full %

1/2

full

%

1/4

full % Empty

May-06 34 0.57 3.42 5.88 8.82 8.82 11.7 26.4 38.2

June 32 0.64 4.24 6.25 9.37 12.5 15.6 21.8 46.2

July 30 0.62 4.18 3.33 6.66 10.1 13.3 23.3 43.2

Aug 30 0.4 2.83 nil 3.33 10.1 16.6 20.1 50.1

Sep 30 1.92 11.57 13.3 16.6 20.1 23.3 16.6 10.1

Oct 31 1.92 10.94 9.67 12.9 16.1 19.3 25.8 16.1

Nov 32 1 5.07 6.25 9.37 12.5 18.7 31.2 15.6

Dec 30 1.06 6.44 10.1 13.3 10.1 23.3 30.1 13.3

Jan-07 31 0.58 4.05 nil 6.45 6.45 19.3 41.9 25.8

Feb 32 0.5 3.11 3.12 3.12 9.37 21.8 25.1 37.5

March 32 0.45 4.08 3.12 6.25 9.37 21.8 31.2 28.1

April 32 0.52 3.21 0 6.25 12.5 15.6 21.8 43.7

May 34 0.58 3.47 6.88 7.82 8.82 11.7 27.4 37.2

June 32 0.63 4.21 6.25 8.37 13.5 16.6 20.8 46.8

July 30 0.64 4.16 4.33 5.66 11.1 12.3 22.3 44.3

Aug 30 0.39 2.83 nil 4.33 9.1 15.6 22.01 50.3

Sep 30 1.91 11.56 14.3 15.6 20.1 24.3 15.6 10.1

Oct 31 1.93 10.91 9.67 12.9 16.1 20.3 24.8 16.1

Nov 32 1.01 5.05 7.25 8.36 12.5 19.7 30.2 15.7

Dec 30 1.06 6.41 10.1 12.3 11.1 24.3 30.1 12.3

Jan-08 31 0.63 6.03 3.33 5.45 5.45 18.3 40.9 26.8

Feb 32 0.48 3.11 4.12 3.12 8.37 21.8 27.2 35.3

March 32 0.43 4.07 3.12 5.25 10.37 22.8 31.2 27.1

April 32 0.51 3.21 1.1 5.25 12.5 15.6 21.8 43.1

57

Index of preponderance of food items for U. vittatus and U. moluccensis May and June 2006.

Fig: 8 c Fig: 8 d

Fig: 8 e Fig: 8 f

58

Index of preponderance of food items for U. vittatus and U. moluccensis July and Aug 2006.

Fig: 9 a Fig: 9 b

Fig: 9 c Fig: 9 d

59

Index of preponderance of food items for U. vittatus and U. moluccensis September and October 2006.

Fig: 10 a Fig: 10 b

Fig: 10 c Fig: 10 d

60

Index of preponderance of food items for U. vittatus and U. moluccensis November and December 2006.

Fig : 11 a Fig : 11b

Fig : 11 c Fig: 11 d

61

Index of preponderance of food items for U. vittatus and U. moluccensis January and February 2007.

Fig: 12 a Fig: 12 b

Fig: 12 c Fig: 12 d

62

Index of preponderance of food items for U. vittatus and U. moluccensis March and April 2007.

Fig: 13 a Fig: 13 b

Fig: 13 c Fig: 13 d

63

Index of preponderance of food items for U. vittatus and U. moluccensis May and June 2007.

Fig: 14 a Fig: 14 b

Fig : 14 c Fig: 14 d

64

Index of preponderance of food items for U. vittatus and U. moluccensis July and August 2007.

Fig: 15 a Fig: 15 b

Fig: 15 c Fig: 15 d

65

Index of preponderance of food items for U. vittatus and U. moluccensis September and October 2007.

Fig: 16 a Fig: 16 b

Fig: 16 c Fig: 16 d

66

Index of preponderance of food items for U. vittatus and U. moluccensis November and December 2007.

Fig: 17 a Fig: 17 b

Fig: 17 c Fig: 17 d

67

Index of preponderance of food items for U. vittatus and U. moluccensis January and February 2008.

Fig: 18 a Fig: 18 b

Fig: 18 c Fig: 18 d

68

Index of preponderance of food items for U. vittatus and U. moluccensis March and April 2008.

Fig: 19 a Fig: 19 b

Fig: 19 c Fig: 19 d