Diet Composition of Bartail Flathead (Platycephalus Indicus) in Northwest of Persian Gulf

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World Journal of Fish and Marine Sciences 5 (1): 35-41, 2013 ISSN 2078-4589 © IDOSI Publications, 2013 DOI: 10.5829/idosi.wjfms.2013.05.01.6614

Diet Composition of Bartail Flathead (Platycephalus indicus) in Northwest of Persian Gulf

12Seyedahmadreza Hashemi and Seyedaminollah Taghavimotlagh

1Department Fisheries, Gorgan University of Agricultural Sciences and Natural Resources, Iran 2Fisheries Research Organization, Tehran, Iran

Abstract: In recent years, the stock of bartail flathead, distributed in Khuzestan Coastal Waters (Iran) has increased dramatically, raising concerns about their predatory impact and their forage requirements. During January 2009 to March 2011, a number of Platycephalus indicus species was captured in main fishing areas of Khuzestan province namely Busafe-Liphe and Bahrakan, northwest of Persian Gulf. The stomach contents of 394 individuals were examined, in which 226 individuals had contained (trace-full) stomachs while 168 individuals had empty stomachs. The value of vacuity index (CV) indicated moderate feeding for this species and percentages of CV in males were higher than in females. Using one-way ANOVA Test, the relationship between CV index and temperature was significant (P<0.05). The analysis of Prey occurrence index (FP) and Relative importance for prey index (IRI) results showed that fish is the main food source for bartail flathead, followed by shrimps as secondary food source and crabs and cuttlefish are accidental food sources. Nine different species of fish and 6 species of invertebrates were observed in the diet. In overall, the analysis of stomach contents forbartail flathead indicated that, Sardinellasindensis andCynoglussarelfishes, dominated the diet which accounted for %15 of the weight and accounted in %16 of all stomachs.

Key words: Diet Composition Persian Gulf Stomach Contents Analysis

INTRODUCTION capturedmainlyby bottom trawl and gillnet [3]. The amount of catches recorded for this species in Khuzestan Information of diet is important forunderstand the Province (Northwest of Persian Gulf) was 410 tons and basic functioning of fish assemblages and is widely used 917 tons during 2000 and 2010 [4]. P. indicusspecies are for ecological work and modeling and is becoming an among the expensive fishes in Khuzestan province (South increasingly important component in ecologically based of Iran) and cost about 6 US $/kg [5, 6]. Because of its management regime. The downward shift of the trophic important role in economy of Khuzestan fishery and also composition of the catch worldwide, which was formerly in Persian Gulf region countries this fish is a target dominated by large carnivorous species [1], has also at species for capture. Different aspects of biological attracted attention towards the trophic status of species. parameters of P. indicus have been studied by different In areas with high fish diversity, such as the Persian authors in Persian Gulf are those in Kuwait waters and in Gulf which hosts over 1500 species of coastal fishes, Hong Kongwaters [7-9]. The objective of this study was the level of the information on the diets of these to provide information pertaining to diet composition of species is often low and difficult to access. this species. According to Smith and Heemstra [2] about 25 species of Platycephalidae belonging to 10 genera have been MATERIALS AND MEIHODS identified around the world. P. indicus is a benthic fish found on sand or mud bottom in different shallow The main fishing areas of P. indicusthe on northwest area of estuary and near shore to depth of 25m [2]. of Persian Gulf are located in Liphe-Busafe and Bahrekan This species is dominant species of Platycephalidae fishing area between 29° 44' to 07 'N and 48° 45' to 49° 50' family, in Khuzestan province (Iran) and is (Fig. 1).

Corresponding Author: Seyedahmadreza Hashemi, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan (Iran), Tel: +989177055568. 35 World J. Fish & Marine Sci., 5 (1): 35-41, 2013

Fig. 1: Location of two landing sites of bartail flathead in Khuzestan Coastal Waters (Iran)

Monthly water samples (During January 2009 to regurgitation of prey that may produce emptier stomachs March 2011) for analysis of environmental parameters in samples than in population, this index may not be very (pH, salinity, temperature and dissolved oxygen) were robust; therefore, some other indices were also used. collected from each station using a Nansen bottle sampler and analyzed as per standard analytical Prey Occurrence Index: The percentage frequency of procedures [10]. A total number of 394 individuals of occurrence of one prey item J, the prey occurrence index, P. indicus were captured during 2009 to 2011 using Fp. This is the ratio of the number of stomachs containing bottom trawl and gill net and instead of also, which the pry item j (Nsj) and number of stomachs that collected from recreational fishermen and then transferred contained food (NS.), in icebox to the laboratory. In the laboratory, total length (±1.0 mm), sex and weight (±0.001 g wet weight) were Fp = Nsjx100/Ns recorded for each fish.Parameters of the length weight relationship were obtained by fitting the power function The different values of this index, allow separation of W=a×FLb to length and weight data where: W is the total the prey items into three categories: If F>50%, the prey are wet weight, is a constant determined empirically, LF is the dominant and characteristic of the predator diet. If 50 % fork length [11]. In order to verify if calculated b was >F>1 0%, the prey eaten are secondary and occur mainly significantly different from 3, the Students t-test was if there is a lack of dominican prey. If F<10%, the prey are employed [12]. eaten accidentally. Stomachs were removed by cutting the alimentary canal anterior to the stomach and posterior to the Relative Importance for Prey Index: The index of relative pylorus and the contents were frozen until processed. importance for a particular prey category i (IRIi), is The qualitative and quantitative analyses of stomach expressed as: contents were done and intensity of feeding [13], vacuity index [14], Prey occurrence index [14], were calculated as IRI = (%N + %W) × %F follows: where %N= the percentage of a prey species by number; Vacuity Index: The index of vacuity or index of emptiness %W=the percentage of a prey species by weight; and (called the vacuity index CV); it is the percentage ratio %F= the percent frequency of occurrence of a prey between the numbers of empty stomachs (ES) and the species. total number of stomachs analyzed (TS). IRI values were calculated as percent IRI values [15]. In calculating IRI values, we excluded several items CV=ESx100/TS appearing in the stomachs, because they were deemed to be non-naturally occurring food items. Several prey This index gives to estimate of the voracity of the species were combined either because of difficulties in predator fish; the more voracious fish species, the lower identification of partially digested prey to species or percentage of empty stomachs. Because of possible because of ecological or taxonomic similarity.

36 World J. Fish & Marine Sci., 5 (1): 35-41, 2013

The data was processed in Excel and SPSS ver.19 minimum total length was 16mm and 1886mm packages. Statistical analysis consisted of one way respectively. Mean±SD weight values were 384±130grand analysis of variance for means of vacuity stomachs in maximum and minimum weight were 140gr and 600 different months and seasons in each sex and used paired grrespectively (Table 2). The length-weight relation were t-test differences for mean vacuity stomachs of male and calculated as W=0.000004L3.10 (n=470,R2 =0.86) for total female during survey. fishes. verifying calculated b with 3, using Students t-test there was no significant difference between calculated b RESULTS and 3 (P>0.05). The results of CV index showed random monthly Fish ranged in size from 146 to 600 mm TL variation in the values (Fig. 2). The results showed that (mean 384mm) and were 16–1886 kg in weight (mean 353 mean Cv index was higher in females than in males. The g). Of the 469 bartail flathead examined, 183 (39%) highest and lowest values were in March and May to contained items in the stomachs. August respectively. There was a significant difference From the total number of caught fishes, 248 and 198 between means of vacuity stomachs of each sex in were males and females respectively and 23 specimens different months. Using one- way ANOVA Test, the were immature. According to Table 1, mean±SD length relationship between CV index and temperature was values for this species were 353±180 and maximum and significant (p<0.05).

Table 1: Average values (±SD) of size corresponding of bartail flathead in Khuzestan Coastal Waters (2009-2011) Month N Male Female Mean W ±SD (gr) Min-max Mean TL±SD (mm) Min-max January 114 82 32 356±72 255-550 362±72 113-1163 February 31 23 6 294±20 224-380 179±20 64-395 March 31 11 17 280±23 201-358 153±23 57-347 April 63 40 23 361±14 266-535 389±72 114-1170 May 33 19 11 317±59 237-550 254±20 11-8410 June 30 19 11 315±43 236-550 264±23 84-1490 July 15 1 13 446±72 317-590 677±72 207-1238 August 13 2 10 357±20 280-515 418±60 141-1097 September 22 6 3 290±23 140-372 185±23 16-344 October 33 6 23 389±72 277-555 525±72 70-1540 November 35 11 23 333±88 235-490 309±40 71-817 December 55 24 28 298±53 285-600 539±63 146-1886 Average 469 248 198 130±384 140-600 180±353 16-1886

Table 2: Fluctuations in intensity of feeding prey of bartail flathead in Khuzestan Coastal Waters (2009-2011) Total Female Male ------Prey N% W% F% IRI% N% W% F% IRI% N% W% F% IRI% Protanidae 1.49 0.42 1.49 0.03 - - - - 9.43 6.83 9.43 6.84 PortanusPelagicus 2.24 0.53 2.24 0.05 - - - - 1.89 1.61 1.89 0.31 Garspidae 1.49 0.74 1.49 0.04 6.25 1.77 6.25 0.55 1.81 1.61 1.81 0.25 Metapeneausaffinis 7.46 8.28 7.46 1.93 15 9.66 15 5.27 9.43 12.90 9.43 11.50 Squila manta 1.49 0.96 1.49 0.05 1.25 0.39 1.25 0.02 3.77 2.82 3.77 1.28 Others crustacean 3.73 4.78 3.73 0.55 2.55 0.98 2.5 0.10 13.21 11.69 13.21 15.66 cuttlefish 2.24 1.06 2.24 0.09 - - - - 1.89 2.42 1.89 0.44 Thrssahimiltoni 3.73 1.59 3.73 0.22 2.5 1.57 2.5 0.14 5.66 9.27 5.66 4.85 Parapenaeopsisstylifera 2.24 2.55 2.24 0.18 - - - - 3.64 6.77 3.64 2.43 Leiognatusbindus 0.75 0.53 0.75 0.01 - - - - 1.89 1.61 1.89 0.31 Cynoglussarel 6.72 4.99 6.72 1.11 5 14.79 5 2.27 9.43 12.50 9.43 11.19 Psudorambuselevatus 7.46 0.53 7.46 0.33 6.25 6.95 6.25 1.44 9.43 12.10 9.43 10.88 Caranussp. 0.75 0.53 0.75 0.01 1.25 3.94 0.98 0.04 1.89 2.02 1.80 0.37 Silagosihama 1.49 2.12 1.49 0.10 1.25 3.74 1.25 0.14 - - - - Nemipetrusjapnicus. 0.75 2.12 0.75 0.05 1.25 3.94 1.25 1.15 - - - - Sardinelasindensis 7.46 5.31 7.46 1.32 6.25 3.94 6.25 0.90 15.09 8.87 15.09 14.92 Others Fish 48.51 62.95 48.51 93.94 51.28 51.25 51.28 88.98 15.09 14.10 15.09 21.38

37 World J. Fish & Marine Sci., 5 (1): 35-41, 2013

Fig. 2: Monthly variation of CV(male and female) of bartail flathead in Khuzestan Coastal Waters (2009-2011)

Table 3: Intensity of feeding prey of bartail flathead in Khuzestan Coastal Waters (Iran) Total Female Male ------Prey Fp% IRI% Fp% IRI% Fp% IRI% Crab 5.22 5.73 8.52 7.5 12.73 7.22 Shrimp 10.64 12.06 17.5 5.37 12.73 12.31 Cuttlefish 2.13 2.24 - - 1.83 0.42 Fish 80.19 79.85 75.5 94 60 64

The values of FP index showed 80% (161 stomachs) for fish, followed by crabs (5.22 %), shrimps (10.64%) and cuttlefish (2.13%). The results of feeding regarding sex are shown in Fig. 3 and 4. The values of FP index of males and females showed in Table 2. Females had a higher volume of fish in stomach contents, but the crab was higher in males. Cuttlefish was not seen in the female's stomachs (Table 3). The results showed that fish is the main food source for bartail flathead, followed by shrimps as a secondary food source and crabs and cuttlefish are Fig. 3: Frequency of prey occurrence in stomachs of accidental food sources. It also shows that when fish bartailflathead (male)in Khuzestan Coastal Waters grows in length, feeding on crustaceans reduces and an (2009-2011) increase feeding on fish occurs. omparison between mean values of environmental parameters and intensity of feeding (Fig. 3) indicated that, there is significant correlation between pH, Water temp., Dissolved oxygen and intensity of feeding (p<0.05). The main fish food items were Cynoglussarel, sardinelasp., Psudorambuselevatus, Thrssahimiltoni, Uepenussulphureus, Leiognatusbindus, Silagosihama, Johniusbelangeri, Nemipetrusjapnicus.., Metapeneausaffinis, Parapenaeopsisstylifera, Squila manta(shrimps); Garspidae and Portanidae (carbs) and Fig. 4: Frequency of prey occurrence in stomachs of S. pharaonis, (cuttlefish). Cynoglussarel, bartailflathead (female)in Khuzestan Coastal sardinelasindensis, were the dominant items in the Waters (2009-2011) stomach. Nine different species of fish and 6 species of dominated the diet, which accounted for %15 of the invertebrates were observed in the diet. Overall, weight and occurred in 16% of all stomachs (Table 2). Sardinellasindensis and Cynoglussarel, Are the fishes Invertebrates were relatively minor constituents of the

38 World J. Fish & Marine Sci., 5 (1): 35-41, 2013 overall diet of bartail flathead, providing only 19.81% of Kongwaters [8, 9]. Spotfin flathead consumes more the total IRI. In contrast, fishes contributed 80.19% of the invertebrates (60%) and is less selective with respect to IRI (Table 2). fish species [26]. The predominance of fish in adult bartail flathead DISCUTION diets attests to the piscivorous nature of bartail flathead and corroborate the findings of other studies [7-9]. The b values in the weight-length model were Invertebrates constituted a minor percentage of the measured close to 3 for p. indicus fishes that indicating overall diet. In Kuwaiti waters, P.indicus feeds on isometric growth [16]. Values of b for Indian waters zoobenthos and its second priority was Shrimps [7]. (the NetravatiGurpur Estuary, Mangalore) wereestimated Knowledge of feeding regimes of fish species is of great 2.99 and 2.91 for male and female respectively [17]. The b importance in understanding their ecological interaction values of weight-length relationship were 3.32 for total [27]. P. indicus having relatively big head and mouth with fish of this species in Kuwait waters [18]. sharp teeth and usually attack and swallow their prey very The variation of b in the different regions can be quickly [28]. caused due to seasonal fluctuations in environmental According to Abdel-Azis et al. [29] and Parrish [30] parameters, physiological conditions of the fish at the presence of food items in the fish diet is related to the time of collection, sex, gonad development and availability of food, food selection and the age of fish. nutritive conditions in the environment of fish [11]. The food preference of predatory fishes is very complex The length-weight relationship is a practical index of the and is influenced by many factors such as, prey condition of fish and may vary over the year according to accessibility, mobility, prey abundance, prey energy exogenous and endogenous factors such as food content prey size selection and seasonal changes [31]. availability, feeding rate, health, sex, gonad development, The diet of most fishes will change with a number of spawning period and preservation techniques [19, 20]. factors, either intrinsic (e.g. size, behavior, taxonomy) or CV value indicated moderate feeding for this species extrinsic (e.g. biotope, region) [32]. and percentages of CV in males were more than in females. In male, higher percentage of empty stomachs was ACKNOWLEGMENTS observed in January and February. The fluctuations in fullness of stomach did show correlation with The present study was carried out within the temperature. During spawning months, majority of mature framework of the research project “Determination of the fish occurred with empty stomachs. This may be due to ecological relationship among economic fishes in the the calorific value of food consumed [21] or faster rate of coastal area of the Persian Gulf” funded by Iranian digestion [22]. The presence of considerable quantities of Fisheries Research Organization (IFRO) and Iran National semi digested matter might be due to the rapid digestion Science Foundation. Special thanks for presentation of that takes place in the tropical waters as the metabolic rate material and spiritual supportive aids and services for this is high [23]. Fishes with empty stomach and poor feeding national project and all colleagues that helped during field activity are common in several species of tropical fishes work. We thank Dr. Maramazi, the manager of the South [24]. of Iran aquaculture fishery research center, Ahwaz. Based on Fp and IRI indexes, the most important food We are also very grateful the experts of the South of Iran item was fish, followed by crustaceans and molluscs. aquaculture fishery research center, Ahwaz for helping Also, the high number of different food items in stomach the project work. content of this species, suggests that they are less selective in their diets and specialize on particular food REFERENCES items. P. indicus are unspecialized and opportunistic 1. Pauly, D., V. Christensen, J. Dalsgaard, R. Froese and carnivores, feeding on a variety in fishes and crustaceans F. Torres Jr. 1998. Fishing down marine food webs. during the day and at night [25]. According to the present Science, 279: 860-863. study most of the item stomachs were similar observation 2. Smith, M.M. and P.C. Heemstra, 1986. Smith's Sea with P. indicusin Kuwaiti waters [7] and in Hong Fishes. Springer Velage, pp: 1047.

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