Sucker fish Echeneis naucrates Linnaeus 1758 of west coast of India

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1 Indian Journal of Geo-Marine Sciences Volume 44(1), January 215 Sucker fish Echeneis naucrates Linnaeus 1758 of west coast of India S.K. Naik 1, Asheesh Shivam 2 & A.B.Kar1 * 1 Fishery Survey of India, Visakhapatanam-53 1, India 2 Fishery Survey of India, Murmugao-43 83, India [ akar51@yahoo.com] Result of the studies made on live sharksucker (commonly known as sucker fish) Echeneis naucrates Linnaeus 1758 collected from November 23 to October 25 from the Central west coast of India is discussed in this study. Study indicated the dominance of male with a sex ratio (M:F) of 1:.4. Length weight relationship for male and female sucker fish was W=.6536 L (r=.98) and W=.262 L (r=.93) respectively. Regression equations between them differed significantly (F= 35.83). There were seven stages of maturity and twelve stages of ova observed in the species. Ova observed were between 5-8 and micrometer division ( mm and mm respectively). Size at first maturity was 51cm. Fish appears to be a batch spawner. About 38% of the fishes were found with empty stomachs. Gut content analysis showed that the food items are mainly cephalopods and juvenile fishes especially lizard fishes, goat fishes, threadfin breams and anchovies. Females were found to be poor feeders. [Key words: Sucker fish, sex ratio, Length-Weight relationship, maturity, ova diameter study, food and feeding] Introduction The members of the family Echeneidae which are commonly known as sucker fishes form ecologically important community in the coastal and oceanic waters. Distributed in the warm waters, they are known to be found in all the oceans. Out of the eight species recorded worldwide, seven species are known to occur in western Indian Ocean (Fischer and Bianchi 1 ). Four species have been reported in the Indian Ocean region. In Indian waters three species of suckerfish viz, Echeneis naucrates (Live Sharksucker), Remora remora (Shark sucker) and Remora brachyptera (Spearfish Remora) have been recorded. However, the species E. naucrates is commonly caught. They associate themselves with host species like sharks, perches, sting rays, turtles, dolphins, whales, dugongs, manatees and even ships for their transportation as well as feeding. They do so as they lack the essential swim bladder to maneuver comfortably. The sucking apparatus of the sucker fish is located at the top of the head which is its modified spiny dorsal fin. It consists of numerous pairs of crests capable of producing strong vacuum helping it to attach to its hosts. But species of genus Echeneis are often found free swimming and found in inshore and off shore waters. Association of the species with sharks, Cetaceans (whales and dolphins), pelagic and reef fish and Sirenians (Dugongs and Manatees) is well established (O Toole 2, Fertl and Landry 3, Williams & Bunkley Williams 4, Mignucei- Giannoni et al 5 and Williams E.H Jr. et al 6 ). Feeding behavior of the species has been studied by various researchers (Smith 7, Strasburg 8, Burn 9 and Marsh et al 1 ).It is one of the least studied fish in Indian waters and biological information on this particular species occurring in the Indian coast is not documented well. In this study an attempt has been made to understand the biology of the commonly occurring sucker fish along the central west coast of India. Materials and Methods For this study a total 126 specimens collected from the sampling stations covered by MFV Matsya Vishwa( Stern Trawler,OAL:36.5m, GRT: T, BHP: 825) and M. F. V Sagarika(Stern Trawler, OAL:28.8m, GRT:186T, BHP:65) of Fishery Survey of India, during their routine survey cruises from Dec 23 to November 25 were used. The samples were collected from the area 11 N to 18 between 35m and 2 m depth using two types of demersal trawl nets viz 27.5 m fish trawl and 3m shrimp trawl. Frozen samples were brought to the laboratory to record the total length, weight, sex, stages of maturity and gut content after thawing. For length-weight analysis TL (tip of snout to tip of upper caudal lobe in centimeter) was taken and weight to the nearest gram was taken. Sex ratio (M: F) was calculated. Length weight relationship W=aL b was calculated as per Le Cren 11. Regression lines of both males and females were tested for significant difference by ANOVA (Snedecor and Cochran 12 ) and significance of variation in the estimate of b from 3 was tested using 't ' test where, t= [(b~3)/se b. ]. Maturity stage was examined and classified as per ICES classification. Ovaries were preserved in 5 % formalin for the study of ova-diameter. Each ovary was weighed to the nearest.1mg. Mass of ova was weighed. From this, 3 sub samples from each lobe (anterior, middle and posterior) were taken and Gilson s fluid was added to it

2 INDIAN J. MAR. SCI., VOL. 44, NO.1 JANUARY 215 and the number of ova was counted and the diameter was measured with the help of an ocular micrometer attached to a binocular microscope. Ova diameter measurements were further analyzed by plotting the ova diameter with the frequency and observing the occurrence of the modes to find out different stages of ova of the species. Gonado-somatic index was estimated by the following formula. Gonado-Somatic Index (GSI) = Weight of gonad X1 Weight of fish Gut content analysis was carried out following Index of Relative Importance (IRI), Pinkas et al 13. Results Sucker fish, was dominated by a single species E. naucrates and is distributed in the area Lat 11 N to 18 N where as only few samples of E. remora were recorded in the area between Lat. 14 N and 15 N. They occurred free swimming in deep as well in shore shallow water depth ranging from 3 85 M. Among the recorded species 9 were males ranging from 28 7 cm in length and weighing gm and 36 were females ranging from the cm in length and weighing gm. A total of 126 specimens consisting of 9 males measuring 28-7cm and 36 females measuring cm were taken for sex ratio analysis. Sex ratio indicated the dominance of male in all the size groups. The male to female ratio was found to be 1:.4.The males completely outnumbered the females in all the size groups except 51-6cm where the female population came close to the male (1:.7) (Table 1). Table.1. Sex ratio(m:f) of E naucrates in the west coast of India Length range(cm) Male Female Ratio : : : :.11 TOTAL :.4 The data for the length weight study was analyzed separately for both the sexes and the equations obtained are as follows. Males : Log W= Log L (r =.98) Female: Log W= Log L(r=.93) The slope for male was significantly different from 3(t=1.4496; df=89). But in case of female, it was not significantly different from 3 (t=3.3272; df=35). ANOVA results obtained for the species are given in table 2. Regression lines for male and females were significantly different (F= ).Hence a combined length weight equations could not be proposed for the species. The results of the detail examination of the ovaries of E. naucrates is given below -In order to study the maturity and ascertain the spawning season 36 females were examined. Maturity stages were recognized both by gross observation as well as by the ova diameter measurements. The description is given below: Immature I Ovary translucent, orange Stage A red in colour, occupy less than 3% of body cavity. Eggs microscopic. Not visible without aid. Frequencies with one mode (5-8 M.D,.5-.8mm), maximum ovum diameter is M.D(.27-.3mm). This stage was common all Maturing Stage B Maturing Stage C,D Mature Stage E, F,G year round. II Ovary translucent, somewhat reddish brown in colour and occupies 4% portion of the body cavity. Eggs are not visible to naked eye, very small in size. Frequencies with one mode (9-12 M.D,.9-.13mm), maximum ovum diameter is 57-6 M.D ( mm). III Ovary light red in colour, occupies 4% of the visceral cavity. Eggs visible. Frequencies with three to five modes, maximum ovum diameter is 97-1 M.D ( mm). IV Ovary large, orange to reddish yellow coloration, reaches upto 7% of the body cavity, lumen filled with eggs, eggs large, opaque, clearly visible. Frequencies with seven modes, maximum ovum diameter is M.D ( mm).

3 NAIK et al.: SUCKER FISH ECHENEIS NAUCRATES LINNAEUS 1758 Ripe Stage H Partial spent Stage I, J.K Fully Spent Stage L V Ovary massive, yellowish in colour, occupies almost entire body cavity. Eggs clearly visible and blood vessels clearly seen on the gonads. Eggs are ready to be released. Frequencies with seven major modes, maximum ovum diameter is M.D( mm). VI Ovary pale, reddish, covers 6% of the body cavity. Opaque eggs, yellowish. Ovary hollow inside. Gonad reduced and flaccid. Blood vessels clearly seen. Eggs partly released. Frequencies with two major modes, maximum ovum diameter is M.D(1.46- VII 1.49mm). Ovary reduced, in a shrunken stage and occupies half of the body cavity. Reddish in colour. Most of the ova released a few are there to be released. Frequencies with two major modes, maximum ovum diameter is M.D ( mm). Resembles stage B( II). The ova diameter frequency in various months has shown that the fish is a batch spawner and has prolonged breeding season. The stages of maturity varies in a different months, even in a particular month almost all stages of maturity were noticed. Hence the ovaries were grouped according to the largest mode in the diameter frequency curve. The results indicated 12 stages of maturity (fig. 1(A to L). Stage A (I) is the immature ovary and has only one group of ova. Fishes upto 41 cm were in this stage. This particular stage was encountered throughout the year. Stage B shows the shifting of the mode to the next diameter group from the immature stock. Fishes of size 45cm comes under this stage. Stage C (III) shows three distinct modes and the shifting of modes from the previous stage. In stage D there appears another two minor modes in the higher ova diameter group. Fishes up to the size 46cm comes under this stage. Stages E, F and G are mature ovaries where the gradual withdrawal of different groups of ova from the reserve stock was noticed. Fishes up to the size 56cm comes under this. The stages F and G shows the advance of the modes of maturing ova. The stages H represents the fully matured/ripe ovary with seven major modes and all groups of ova. Further emergence of maturing group of ova was not encountered after this stage and spawning started after this. Fishes up to 61cm come under this. The stages I,J and K indicates partial spent ovaries. In stage I two major modes wire there in the beginning and subsequently due to spawning activities there are no modes however there were few minor modes to the last. Above 125 M.D (1.37mm) there were no ova. In stage J however due to spawning activities only two major modes were noticed and they were in the last. Above 136 M.D (1.49mm) there were no ova. In the stage K spawning was more and very few minor modes were noticed with no ova beyond 112 M.D(1.23mm). The occurrence of the three stages of ova were more during different times of the year. The stage L represents the completely spent ovary. It indicates the spawning activity is intense and all groups of matured ova are released except one mode in the beginning. This is clear that this group of ova will be there during the resting stage of ovary and is carried over to the succeeding season for the spawning activity. All these indicates that the spawning of the species is a continuous process. For this study the percentage of maturing and mature ovaries was taken into consideration. When the % was plotted against the total length a sigmoid curve was obtained (fig.2). This curve shows that 5% of fish are mature at 51 cm, 8% at 56cm and almost all fishes over 58cm. Hence the fish attains first maturity in the size 51cm (5% mature ovaries). From the figure 3 it could be seen that all individuals less than 4cm were immature (stage I). Fish maturing at 41-5cm length and 5% maturity was attained at 51-6cm. Maturing stages as well as mature specimens were encountered in this length group. However fully matured, partial spent and fully spent ovaries were encountered in the length range 61-7cm. The Gonado Somatic Index (GSI) varied from.19 (stage I) to 1.64(stage VII) in the case of male. However in the case of female it was.51(stage I) to 7.59(stage IV), 8.65(stage V) and 1.65(stage VII), which clearly indicates that stage IV and V are the mature and ripe stages and spawning activity starts in the stage VI and it is intensive in stage VII(fig. 4). Among the stomachs of 126 specimens examined, 15.1 % were gorged, 27.8 % were full, 7.9 % three fourth, 1.3% half full,.8% one fourth and 38.1% were empty.

4 INDIAN J. MAR. SCI., VOL. 44, NO.1 JANUARY 215 Table.2.Comparison of regression lines (ANOVA) of E.naucrates (male & female) Source of Df (n-1) SSQ SSQ SSQ B Df SSQ MSSQ Variation X Y XY Within Male Female Deviation from individual regression (MSSR) Pooled data (MSSP) Difference between slops (MSSE) Individual regression(msse/mssr) Total Data Between adjusted mean MSSA Individual interception or elevation(mssa/mssp): M a t u r i t y ( % ) G S 6 I 5 4 % 3 2 Total Length(cm) Fig.2.Size at first maturity of E.naucrates in the West coast of India. ( ) Stage I StageII Stage III Stage IV Stage V Stage VI Stage VII Stages of Gonads Male Female Fig.4.Gonado Somatic Index(GSI) of E. naucrates in the West coast of India Fig.3. Relative proportion of gonad stages and maturity(%) of E. naucrates(female)

5 NAIK et al.: SUCKER FISH ECHENEIS NAUCRATES LINNAEUS L,1(Stage-VII) K,9(Stage-VI) J,7(Stage-VI) I,6(Stage-VI) H,4(Stage-V) G,1(Stage-IV) Frequency of Ova(%) F,1(Stage-IV) E,1(Stage-IV) D,2(Stage-III) C,1(Stage- III) 5. B,1(Stage-II) A,2(Stage-I) Ova Diameter in Micro Meter Divisions Fig.1. Ova-diameter frquency polygons of various maturing stages showing the position and progression of modes during maturation of E.naucrates

6 INDIAN J. MAR. SCI., VOL. 44, NO.1 JANUARY 215 Among males 29.5% of the stomachs were empty and in the case of female 71.6% were empty. In males the average volume of food per fish was 7.2 ml. and female 6.9 ml. Index of Relative Importance (IRI) (Pinkas et al 13,) was used to ascertain the dietary composition by taking into consideration the percentage, number, volume and frequency of occurrence of the prey. In the species E. naucrates, Loligo duvauceli composed the bulk of the diet (45% vol, 66.5% IRI) and formed the most important and abundant prey. Second most important and abundant prey was lizard fish (Saurida tumbil) which contributed 17.7% by volume, 26.3% by number and with an IRI of 21.5%. Other two dominant items were Upeneus spp. with an IRI of 6.8% and Saurida undosquamis with an IRI of 3.9%. Rest of the items accounted for < 1% of the diet and all together they contributed 1.3% IRI (table 3). Table.3. Index of Relative Importance of E.naucrates in the West coast of India Species/groups %No %Vol IRI Loligo duvauceli Saurida tumbil Upeneus spp Saurida undosquamis Stolephorus commersoni Nemipterus japonicus N. mesoprion Leiognathus spp Lutjanus spp Crab Decapterus russelli Semi digested fish Epinephelus diacanthus Aluterus spp Cynoglossus spp Other cephalopods Discussion Studies on the Sucker fish in Indian coast is limited to only reporting of occurrence. There is no clear study on the association of the species with the host species. As it is not taken commercially hence aimed fishery does not exist for the species and due to lack of the availability of specimens the biological studies for this species has not been carried out in Indian coasts. However the anatomical structure, the way of association with host species and its feeding pattern made the species unique to be studied. Out of the four species recorded in the Indian Ocean only three are recorded and documented in Indian waters. Present study was specifically undertaken to throw some light on a least studied fish having some interesting features. This is recorded almost everywhere around the world and mostly in tropical waters. It is not very clear whether the species is an active feeder or takes the rejected food of the host or the host fecal matters. Williams Jr. et al 6 reported fecal matters in the gut of the shark sucker in the Australian and South African waters and established the Echeneid and Sirenians association. Presence of fin fishes, shell fishes and mollusks in the gut of the species and also the percentage of digestion(quality of gut)clearly indicates that this species is just like other fin fishes and must be collecting its own food. But it is a well established fact that the species lacks a swim bladder and rely on others (host species) for locomotion hence it can not be an active feeder. Considering this it can be said that the species gets its food from some other sources and the following can be said about the possible ways of getting the food. By analyzing the gut contents it is clearly seen that there is no trace of fecal matters of the Sirenians (Dugongs and Manatees). Hence the possibility of association with Sirenians and depending on them for food as reported earlier (Williams Jr. et al 6 ) is completely ruled out. Next thing to ponder is the association of the species with a piscivorous host for the rejected/leftover food of host species for its own consumption. This appears to be correct as the gut comprised of mostly bony fishes and cephalopods. It could be with sharks or with Cetaceans like dolphins, which is not confirmed. The feeding behavior of shark suggests that the host species could be shark. In depth biological analysis indicated that the species is just like other bony fishes. The sex ratio indicated the dominance of male in the population and the dominance was more in the higher length class (51-6cm and 61-7cm). Length weight study indicated a positive allometry however the t test indicated that the slope for male was significantly different from 3

7 NAIK et al.: SUCKER FISH ECHENEIS NAUCRATES LINNAEUS 1758 and also the ANOVA study indicated that the regression coefficient for the both the sexes significantly differ and hence a single equation combining both the sexes could not be derived. Fish attains maturity at 51 cm. Reproductive studies such as ovary maturity and microscopic study i.e ova diameter study has indicated that there are seven stages of maturity observed and there are 12 different stages of ova encountered in the seven different maturity stages. The species has prolonged breeding season and is a batch spawner. GSI indicated that stage IV and V are mature and ripe stages and spawning activity starts in the stage VI and it is more in stage VII. The feeding pattern indicated that the species is associated with a piscivorous host. Preference for food in the species is also ruled out as the fish does not search for its food instead it takes food that are lost or rejected by the host. Gut intensity indicated that the females were poor feeder (75% empty stomach). Dietary composition indicated the dominance of squid (L. duvauceli) with an IRI of 66.5% followed by Lizard fish (S. tumbil) with an IRI of 21.5%. Other items leaving Upeneus spp. and S. undosqamis contributed very little to the composition. Conclusion One of the least studied fish in the Indian waters is the shark suckerfish. Present study has revealed some biological aspects of the fish. It is clearly understood that in the west coast of India the host species of the sucker fish are not the Sirenians (Dugongs and Manatees) and it could be either shark or dolphin or whales. Next important aspect is that the sucker fish associate with the host probably for three main causes i.e locomotion, protection (to save from predators) and food. Acknowledgement Authors are grateful to the Director General, Fishery Survey of India, Mumbai for suggesting the topic and encouragement. References 1. Fisher, W. and G. Bianchi., (eds), FAO Species identification sheets for fishery purpose- Western Indian Ocean( fishing area 51), Vol.V(1984) FAO, Rome. 2. O Toole, B., Phylogeny of the species of the superfamily Echeneoidea (Perciformes: Carangoidei: Echeneidae, Rachycentridae, and Coryphaenidae), with an interpretation of echeneid hitchhiking behaviour. Canadian Journal of Zoology., 8(22) Fertl, D. and Landry, A. M., Sharksucker (Echeneis naucrates) on a bottlenose dolphin (Tursiops truncatus), and a review of other cetacean-remora associations. Marine Mammal Science., 15(1999) Williams Jr., E. H. and Bunkley-Williams, L., Parasites of Offshore, Big Game Sport Fishes of Puerto Rico and the Western North Atlantic Mayagüez, Puerto Rico: Puerto Rico Department of Natural and Environmental Resources and Department of Biology(1996) University of Puerto Rico, 384 p. 5. Mignucci-Giannoni, A. A., Beck, C. A., Montoya- Ospina, R. A. and Williams Jr., E. H. Parasites and commensals of the West Indian manatee from Puerto Rico. Journal of the Helminthological Society of Washington., 66(1999) Williams Jr., E.H., Mignucci- Giannoni,A.A., Bunkleywilliams,L., Bonde,R.K., Selfsullivan,C., Preen,A. and Cockcroft, V.G. Echeneid-sirenian associations, with information on sharksucker diet, Journal of Fish Biology.,(23) Smith, J. L. B., The Sea Fishes of Southern Africa. Capetown, South Africa: Central News Agency.,(195) 55 p. 8. Strasburg, D. W., Notes on the diet and correlating structures of some central Pacific echeneid fishes. Copeia.,( 1959) Burn, D. M., The digestive strategy and efficiency of the West Indian manatee, Trichechus manatus. Comparative Biochemistry and Physiology., 85A (1986) Marsh, H., Beck, C. A. and Vargo, T. A., comparison of the capabilities of dugongs and West Indian manatees to masticate sea grasses. Marine Mammal Science., 15(1999) Le Cren E D. The length-weight relationship and seasonal cycle in gonad weight and condition in the perch (Percafluviatilis).I. Anion. Ecol., 2(1951) Snedecor,G.W and Cochran, W.G. Statistical Methods. Lowa State University Press.,(1967). 13. Pinkas, L., Olipahnt,M.S. and Iverson,I.L.K. Food habits of albacore, bluefin tuna, and bonito in Californian waters. Calif. Dep.Fish Game, Fish. Bull.,(1971) 152: 1-15.

8 INDIAN J. MAR. SCI., VOL. 44, NO.1 JANUARY 215