Ecological Questions 32 (2021) 2: 7-25 http://dx.doi.org/10.12775/EQ.2021.010

Ichthyofaunal integrity and environmental features trade-off in the Sundarbans,

Priyankar Chakraborty1*, Subhrendu Sekhar Mishra2, Saresh Chandra Saren2, Anwesha Sengupta2, Kranti Yardi1

1Bharati Vidyapeeth Institute of Environment Education and Research (BVIEER), Bharati Vidyapeeth (Deemed to be University), Pune 411 043, India 2Marine Section, Zoological Survey of India, 700 016, India *corresponding author e-mail: [email protected] Received: 2 May 2020 / Accepted: 14 September 2020

Abstract. Herein, we studied the ichthyofaunal diversity of the Bidyadhari River in the Indian Sundarbans for three consecutive months (April 2018-June 2018). The collected in this study were netted from two collection points using bag nets. We also measured some environmental parameters during the time of netting. From the collection, we determined the Simpson’s index of diversity (1-D), the Shannon-Wiener index (H), evenness (E) and the Sorenson’s coefficient of community (CC) to find out the richness, abundance, evenness and the levels of similarity of the two collection points. We also converted the H values to their true diversities (effective number of species [ENS]) for an adequate comparison. The indices and coefficient (H = 3.72-3.94, E = 0.830-0.832, 1-D = 0.973-0.979 and CC = 0.87) indicate that the overall integrity of biodiversity of the two collecting points is high. From the true diversity values, we ascertained that the first point, having 62 species of fishes, is 1.24 times as diverse as the second one, having 50 species. We have attributed the fish diversity to a compound of abiotic and biotic factors, which we explain in the discussion part. We also documented 20 fish species, new records for the Indian Sundarbans; some are new records from West Bengal. Furthermore, we discuss the possible reasons for their occurrence. Our study brings the number of fish species recorded from the Indian Sundarbans to 378.

Keywords: , distribution, diversity indices, ecology, , range extension, salinity

1. Introduction ing the biotic integrity of waterways (Karr, 1981; Wel- comme et al., 2006). Fish diversity consists of species One of the end goals of conservation is to designate zones richness (number of species in a characterized territory), for rebuilding or protection. To effectively understand the species abundance (relative number of species) and phy- strength of a conservation or restoration framework, recog- logenetic diversity (connections between various groups nizing the organic components in a community is required of species). These three are related to shifts in environ- (Marzluff and Ewing, 2008). Researchers need to pro- mental features and changes in fish assemblage seasonally pose straightforward, engineered and—if possible—cheap (Brinda et al., 2010). means to assess the natural status of streams and rivers The Sundarbans forest lies in the eastern In- (Darwall and Vie’, 2005). dian state of West Bengal, comprising about half of the Their peculiar life-history traits, versatility and af- total mangrove area of India; 2112 sq. km (FSI, 2019). fectability to changes in natural surroundings make fishes It is one of the most productive ecosystems globally, and great bio-markers and are regularly utilized for apprais- the local people depend on it for sustenance (Andharia, 8 Priyankar Chakraborty, Subhrendu Sekhar Mishra, Saresh Chandra Saren, Anwesha Sengupta, Kranti Yardi

2020). Fishes considerably subsidize the economy of the the Bay of Bengal in the South. The Indian Sundarbans is region (Mishra and Gopi, 2017). a UNESCO world heritage site with rich floral and faunal In the present case study, we looked at the diversity diversity (Sarkar and Bhattacharya, 2003). Mangrove plant of fish species, their dominance and their similarity in the species of the family Rhizophoraceae dominates the delta two fish collection points on the Bidyadhari River in the (Barik and Chowdhury, 2014). Indian Sundarbans. We tried to recognize the role of envi- For this study, we carried out ichthyofau- ronmental factors in the composition of the region’s fishes. nal sampling at two collection points/stations (hereaf- Also, some species of fishes we encountered are new re- ter also referred to as community)-point 1: 22°02.75’N, cords for the Indian Sundarbans and West Bengal. These 88°44.48’E and point 2: 21°59.68’N, 88°42.76’E on the records give us insight into their distribution and the pos- Bidyadhari River, a principal river system in the Sundar- sible reasons for their range extension. We have provided bans (Figure 1). brief taxonomic descriptions of the newly recorded fishes in the results section. 2.2. Field Sampling and Taxonomic Analysis From April 2018 to June 2018, the summer season and the 2. Materials and Methods beginning of monsoon, we accompanied fishers to the two collecting stations on the Bidyadhari River for ten consecu- 2.1. Study Area tive days every month. The fishers used ‚Behundi/ Benthi Jaal’, a form of bagnet. The net had a width of 40 m, length 62 The locationFor of the this Sundarbans study, wemangrove carried delta out is betweenichthyofaunal of 53 msampling and a height at oftwo 14 m,collection with the tapering points/stations end having 21°27’30”N to 22°30’00”N (latitude) and 89°02’00”E to a 2.8 m diameter. The mesh size was 1 mm, made of nylon 63 90°00’00”E(hereafter (longitude) also referred (Padhy et al.,to 2020).as community) It lies in the- pointmonofilament. 1: 22°02.75'N, The fishers 88°44.48'E deployed the andnets rightpoint before 2: eastern Indian state of West Bengal, bounded by the Bangla- the onset of high tide and the soak time was for three hours. 64 desh21°59.68'N, Sundarbans in 88°42.76'E the east, the River on theHooghly Bidyadhari in the west, River, The pHa principal value and waterriver temperaturesystem in were the measuredSundarbans using 65 Nadia(Fig districture 1 in). the north (the Dampier-Hodges line) and portable meters (HI98121, Hanna Instruments Inc.). The

66

67 FigureFigure 1. Map 1. showing Map showing the two fish the collectiontwo fish pointscollection on the pointsBidyadhari on theRiver. Bidyadhari Inset map: River.Location Inset of the map: Sundarbans Location (box) of in the the 68 eastern Indian state of WestSundarbans Bengal (WB) (box) in the eastern Indian state of West Bengal (WB). 69 2.2. Field Sampling and Taxonomic Analysis 70 From April 2018 to June 2018, the summer season and the beginning of monsoon, we 71 accompanied fishers to the two collecting stations on the Bidyadhari River for ten consecutive 72 days every month. The fishers used 'Behundi/ Benthi Jaal', a form of bagnet. The net had a width 73 of 40 m, length of 53 m and a height of 14 m, with the tapering end having a 2.8 m diameter. The 74 mesh size was 1 mm, made of nylon monofilament. The fishers deployed the nets right before 75 the onset of high tide and the soak time was for three hours. The pH value and water temperature 76 were measured using portable meters (HI98121, Hanna Instruments Inc.). The salinity of the 77 water was measured using a refractometer (ERS-10, Erma Inc.). We also measured dissolved Ichthyofaunal integrity, hydrological and environmental features trade-off in the Sunderbans, India 9

salinity of the water was measured using a refractometer ard deviation values of environmental parameters were cal- (ERS-10, Erma Inc.). We also measured dissolved oxygen culated using the statistics package of Microsoft® Excel®. (DO-5509, Lutron Electronic Enterprise Co., Ltd.) and the The Shannon values were turned to true biodiversity val- euphotic depth (using a Secchi disk). ues (ENS) by calculating their exponents in Microsoft® The fish were collected opportunistically from the Excel®. catch. They were fixed in 10% formalin and later stored in 70% ethanol. The specimens were deposited and cata- logued in the national zoological collection at the Zoologi- 3. Results cal Survey of India. Counts and measurements were made on the left side of fish specimens using a digital vernier calliper (CD-6” ASX, Mitutoyo Co.) and stereoscopic mi- 3.1. Ichthyofaunal Composition croscope (EZ4, Leica Microsystems). 109 and (14.2%) with 16 species. TheThe fourthichthyofaunal ordercomposition is of theGobiiformes two collecting points (9.8%) with 11 is 446 individuals, comprising 112 species belonging to 88 2.3. Species Composition and Nomenclature 110 species, followed by (6.2%) withgenera, seven in 43 familiesspecies. and 17 orders,Cumulatively, under two classes: these five orders We followed standard literature to identify the fishes (e.g., Chondrichthyes and . We collected 62 spe- Whitehead, 1985; Talwar and Jhingran, 1991; Smith-Vaniz, cies of fishes from the first community and 50 species from 111 comprise 70% of1999). the We usedtotal online speciesdatabases to ascertain encountered. valid scien- the second The one. Therest complete 30% list of fishesis comprisedcollected from of 12 orders: tific names and the current systematic position of the fami- both points is in Table 1, following the current classifica- lies (e.g., Fricke et al., 2021; Van der Laan et al., 2021). tion (Van der Laan et al., 2021) with their respective IUCN 112 Siluriformes (5.3%),We used theMugiliformes current conservation status (4.5%), in the International conservation statuses. There (4.5%), was no notable Acanthuriformes difference in (4.5%), Union for Conservation of Nature (IUCN) Red List (2021) fish species composition amongst the three months. for each recorded species. The fish fauna of the two points showed that commu- 113 (1.8%), Anguilliformes (1.8%),nity 1 has aCentrarchiformes higher number of fish species. The (1.8different%), orders of fish and their representation in percentage (Figure 2.4. Statistical Analysis 114 (1.8%), Myliobatiformes (0.9%), 2)(0.9%), are as follows: PerciformesCichliformes (23.2%) with 26 (0.9%)species, fol- and Diversity indices (Simpson’s, Shannon-Wiener and even- lowed by (17%) with 19 species and Clu- ness) were computed using the PAST (PAleontological peiformes (14.2%) with 16 species. The fourth order is 115 (0.9%). STatistics) software version 3.20 (Hammer et al., 2001). (9.8%) with 11 species, followed by Scombri- The Sorenson’s similarity coefficient, the mean and stand- formes (6.2%) with seven species. Cumulatively, these five

23,2 29,6

6,2 17

9,8 14,2

Figure 2. Major fish orders (expressed in percentage) from the two collection points in the Indian Sundarbans Carangiformes Clupeiformes Gobiiformes Scombriformes Others (n=12) 116 117 Figure 2. Major fish orders (expressed in percentage) from the two collection points in the Indian 118 Sundarbans. 119 Fish species contributing the highest dominance from the collection: Amblypharyngodon 120 mola-27 individuals, Bregmaceros mcclellandi-22 individuals, Escualosa thoracata-21 121 individuals, Puntius sophore-13 individuals, Gonialosa manmina-12 individuals, Coilia 122 ramcarati-11 individuals, Periophthalmus novemradiatus-10 individuals, Ilisha kampeni-10 123 individuals, Salmostoma bacaila-10 individuals and Planiliza tade-10 individuals. 124 We recorded 20 fish species for the first time from the Indian Sundarbans region (Table 125 1). Our study effectively brings the total number of fish species documented from the Indian 126 Sundarbans to 378. Some of the fishes recorded are new records from West Bengal as well.

127 Table 1. The list of fishes collected from the two points in the Indian Sundarbans (explanations: NE, not 128 evaluated; DD, data deficient; LC, least concern; VU, vulnerable; NT, near threatened; *, new records). Order Family Species Common name IUCN status Myliobatiformes Dasyatidae Brevitrygon Scaly whipray DD 10 Priyankar Chakraborty, Subhrendu Sekhar Mishra, Saresh Chandra Saren, Anwesha Sengupta, Kranti Yardi

orders comprise 70% of the total species encountered. The racata-21 individuals, Puntius sophore-13 individuals, rest 30% is comprised of 12 orders: Siluriformes (5.3%), Gonialosa manmina-12 individuals, Coilia ramcarati-11 Mugiliformes (4.5%), Cypriniformes (4.5%), Acanthuri- individuals, Periophthalmus novemradiatus-10 individu- formes (4.5%), Tetraodontiformes (1.8%), Anguilliformes als, Ilisha kampeni-10 individuals, Salmostoma bacaila-10 (1.8%), Centrarchiformes (1.8%), Beloniformes (1.8%), individuals and Planiliza tade-10 individuals. Myliobatiformes (0.9%), Aulopiformes (0.9%), Cichli- We recorded 20 fish species for the first time from the formes (0.9%) and Gadiformes (0.9%). Indian Sundarbans region (Table 1). Our study effectively Fish species contributing the highest dominance from brings the total number of fish species documented from the collection: Amblypharyngodon mola-27 individuals, the Indian Sundarbans to 378. Some of the fishes recorded Bregmaceros mcclellandi-22 individuals, Escualosa tho- are new records from West Bengal as well.

Table 1. The list of fishes collected from the two points in the Indian Sundarbans (explanations: NE, not evaluated; DD, data deficient; LC, least concern; VU, vulnerable; NT, near threatened; *, new records).

Order Family Species Common name IUCN status Brevitrygon imbricata Myliobatiformes Dasyatidae Scaly whipray DD (Bloch & Schneider, 1801) Gymnothorax tile Anguilliformes Muraenidae Indian mud moray LC (Hamilton, 1822) lepturus Anguilliformes Slender conger LC (Richardson, 1845) Escualosa thoracata Clupeiformes Clupeidae White sardine LC (Valenciennes, 1847) Gonialosa manmina Clupeiformes Clupeidae River gizzard shad LC (Hamilton, 1822) longiceps Clupeiformes Clupeidae Indian oil sardine* LC Valenciennes, 1847 Sardinella fimbriata Clupeiformes Clupeidae Fringescale sardinella* LC (Valenciennes, 1847) Tenualosa toli Clupeiformes Clupeidae Toli shad VU (Valenciennes, 1847) Setipinna taty Clupeiformes Engraulidae Scaly hairfin anchovy LC (Valenciennes, 1848) Setipinna tenuifilis Clupeiformes Engraulidae Common hairfin anchovy DD (Valenciennes, 1848) Coilia ramcarati Clupeiformes Engraulidae Ramcarat grenadier anchovy DD (Hamilton, 1822) Thryssa gautamiensis Babu Rao, Clupeiformes Engraulidae Gautama thryssa DD 1971 Thryssa kammalensoides Clupeiformes Engraulidae Godavari thryssa* DD Wongratana, 1983 Thryssa spinidens Clupeiformes Engraulidae Bengal thryssa* DD (Jordan & Seale, 1925) commersonnii Clupeiformes Engraulidae Commerson’s anchovy LC Lacepede, 1803 Clupeiformes Pristigasteridae Raconda russeliana Gray, 1831 Raconda LC Pellona ditchela Valenciennes, Clupeiformes Pristigasteridae Indian pellona LC 1847 Ilisha megaloptera Clupeiformes Pristigasteridae Bigeye ilisha LC (Swainson, 1838) [11]

Order Family Species Common name IUCN status Ilisha kampeni (Weber & De Clupeiformes Pristigasteridae Kampen’s ilisha LC Beaufort, 1913) Cirrhinus mrigala (Hamilton, Cypriniformes Mrigala LC 1822) Cypriniformes Cyprinidae Pethia ticto (Hamilton, 1822) Tic-tac-toe barb LC Puntius sophore (Hamilton, Cypriniformes Cyprinidae Pool barb LC 1822) Salmostoma bacaila (Hamilton, Cypriniformes Danionidae Large razorbelly LC 1822) Amblypharyngodon mola Cypriniformes Danionidae Mola carplet LC (Hamilton, 1822) Siluriformes Plotosidae Plotosus canius Hamilton, 1822 Gray NE Siluriformes Bagridae Mystus gulio (Hamilton, 1822) Long whiskers catfish LC Siluriformes Bagridae Sperata seenghala (Sykes, 1839) Giant river-catfish LC Netuma thalassina Siluriformes Giant sea catfish NE (Ruppell, 1837) nenga Siluriformes Ariidae Engraved catfish NE (Hamilton, 1822) arius Siluriformes Ariidae Threadfin sea catfish LC (Hamilton, 1822) Harpadon nehereus Aulopiformes Synodontidae Bombay duck NT (Hamilton, 1822) Bregmaceros mcclellandi Gadiformes Bregmacerotidae Unicorn cod NE Thompson, 1840 Pampus chinensis Scombriformes Stromateidae Chinese silver pomfret NE (Euphrasen, 1788) Pampus argenteus Scombriformes Stromateidae Silver pomfret NE (Euphrasen, 1788) Scomberomorus lineolatus Scombriformes Scombridae Streaked seerfish* LC (Cuvier, 1829) Scomberomorus guttatus Scombriformes Scombridae Indo-Pacific king mackerel DD (Bloch & Schneider, 1801) Lepturacanthus savala Scombriformes Trichiuridae Savalai hairtail NE (Cuvier, 1829) Lepturacanthus pantului Scombriformes Trichiuridae Coromandel hairtail DD (Gupta, 1966) Eupleurogrammus glossodon Scombriformes Trichiuridae Longtooth hairtail* NE (Bleeker, 1860) Gobiiformes butis (Hamilton, 1822) Crazy fish LC Boleophthalmus boddarti Gobiiformes Boddart’s goggle-eyed LC (Pallas, 1770) Odontamblyopus rubicundus Gobiiformes Gobiidae Rubicundus eelgoby LC (Hamilton, 1822) Pseudapocryptes elongatus Gobiiformes Gobiidae Elongate mudskipper LC (Cuvier, 1816) Periophthalmus novemradiatus Gobiiformes Gobiidae Pearse’s mudskipper DD (Hamilton, 1822) [12]

Order Family Species Common name IUCN status cyanomos Gobiiformes Gobiidae Threadfin blue goby* LC (Bleeker, 1849) Glossogobius giuris Gobiiformes Gobiidae Tank goby LC (Hamilton, 1822) Scartelaos histophorus Gobiiformes Gobiidae Walking goby LC (Valenciennes, 1837) Trypauchen vagina Gobiiformes Gobiidae Pink worm goby LC (Bloch & Schneider, 1801) microlepis Gobiiformes Gobiidae Maned goby* LC (Bleeker, 1849) Gobiopsis macrostomus Gobiiformes Gobiidae Lockjaw goby LC Steindachner, 1861 Carangiformes Latidae Lates calcarifer (Bloch, 1790) Barramundi LC Carangiformes Sphyraenidae Sphyraena jello Cuvier, 1829 Pickhandle * NE Eleutheronema tetradactylum Carangiformes Polynemidae Fourfinger threadfin NE (Shaw, 1804) Leptomelanosoma indicum Carangiformes Polynemidae Indian threadfin NE (Shaw, 1804) Polynemus paradiseus Linnaeus, Carangiformes Polynemidae Paradise threadfin LC 1758 Pseudorhombus arsius Carangiformes Paralichthyidae Largetooth flounder NE (Hamilton, 1822) Carangiformes ovata Richardson, 1846 Ovate sole* LC Cynoglossus lingua Hamilton, Carangiformes Cynoglossidae Long tonguesole LC 1822 Cynoglossus quadrilineatus Carangiformes Cynoglossidae Fourlined tonguesole* LC (Bleeker, 1851) Cynoglossus cynoglossus Carangiformes Cynoglossidae Bengal tonguesole LC (Hamilton, 1822) Cynoglossus arel Carangiformes Cynoglossidae Largescale tonguesole DD (Bloch & Schneider, 1801) Cynoglossus semifasciatus Day, Carangiformes Cynoglossidae Bengal tonguesole* DD 1877 Cynoglossus macrolepidotus Carangiformes Cynoglossidae Largescale tonguesole* NE (Bleeker, 1851) Paraplagusia bilineata Carangiformes Cynoglossidae Double-lined tonguesole NE (Bloch, 1787) Toxotes chatareus Carangiformes Toxotidae Spotted archerfish LC (Hamilton, 1822) sexfasciatus Quoy Carangiformes LC & Gaimard, 1825 commersonnianus Carangiformes Carangidae Talang queenfish LC Lacepede, 1801 Carangiformes Carangidae Scomberoides tala (Cuvier, 1832) LC Megalaspis cordyla Carangiformes Carangidae LC (Linnaeus, 1758) Oreochromis mossambicus Cichlidae Mozambique tilapia VU (Peters, 1852) [13]

Order Family Species Common name IUCN status Strongylura strongylura Beloniformes Belonidae Spottail needlefish NE (van Hasselt, 1823) limbatus Beloniformes Hemiramphidae Congaturi LC (Valenciennes, 1847) Planiliza macrolepis Mugiliformes Mugilidae Largescale LC (Smith, 1846) Mugiliformes Mugilidae Planiliza tade (Fabricius, 1775) Tade mullet DD Chelon melinopterus Mugiliformes Mugilidae Otomebora mullet LC (Valenciennes, 1836) Mugiliformes Mugilidae Mugil cephalus Linnaeus, 1758 Flathead grey mullet LC Rhinomugil corsula Mugiliformes Mugilidae Corsula mullet LC (Hamilton, 1822) Datnioides polota Acanthuriformes Lobotidae Silver tiger perch LC (Hamilton, 1822) Photopectoralis bindus Acanthuriformes Leiognathidae Orangefin ponyfish NE (Valenciennes, 1835) Nuchequula blochii Acanthuriformes Leiognathidae Twoblotch ponyfish NE (Valenciennes, 1835) Nuchequula gerreoides Acanthuriformes Leiognathidae Decorated ponyfish NE (Bleeker, 1851) Scatophagus argus Acanthuriformes Scatophagidae Spotted scat LC (Linnaeus, 1766) Lagocephalus spadiceus Tetraodontiformes Tetraodontidae Half-smooth golden puffer LC (Richardson, 1845) Lagocephalus guentheri Miranda Tetraodontiformes Tetraodontidae Diamondback puffer* LC Ribeiro, 1915 Centrarchiformes Terapontidae Terapon theraps Cuvier, 1829 Largescaled terapon LC Centrarchiformes Terapontidae Terapon jarbua (Fabricius, 1775) Tiger perch LC Parambassis lala (Hamilton, Perciformes Ambassidae Hi-fin glassy perchlet* NT 1822) Parambassis ranga Perciformes Ambassidae Indian glassy fish LC (Hamilton, 1822) Sillaginopsis domina Perciformes Sillaginidae Flathead sillago NE (Cuvier, 1816) Perciformes Sillaginidae Sillago sihama (Fabricius, 1775) Silver sillago LC Gerres macracanthus Bleeker, Perciformes Gerreidae Long spined silverbiddy* NE 1854 Perciformes Gerreidae Gerres setifer (Hamilton, 1822) Small Bengal silverbiddy NE Pomadasys maculatus Perciformes Haemulidae Saddle grunt LC (Bloch, 1793) Acanthopagrus berda Perciformes Sparidae Goldsilk seabream LC (Fabricius, 1775) Acanthopagrus datnia Perciformes Sparidae Bengal yellowfin seabream DD (Hamilton, 1822) Rhabdosargus sarba Perciformes Sparidae Goldlined seabream LC (Gmelin, 1789) Otolithes ruber Perciformes Tigertooth croaker* LC (Bloch & Schneider, 1801) 14 Priyankar Chakraborty, Subhrendu Sekhar Mishra, Saresh Chandra Saren, Anwesha Sengupta, Kranti Yardi

Order Family Species Common name IUCN status Chrysochir aurea (Richardson, Perciformes Sciaenidae Reeves croaker LC 1846) Perciformes Sciaenidae Pennahia aneus (Bloch, 1793) Donkey croaker* LC Johnius dussumieri Perciformes Sciaenidae Bearded croaker LC (Cuvier, 1830) Johnius borneensis Perciformes Sciaenidae Sharpnose hammer croaker LC (Bleeker, 1851) Johnius belangerii Perciformes Sciaenidae Belanger’s croaker LC (Cuvier, 1830) Perciformes Sciaenidae Johnius carouna (Cuvier, 1830) Caroun croaker* LC Perciformes Sciaenidae Johnius coitor (Hamilton, 1822) Coitor croaker LC Otolithoides pama Perciformes Sciaenidae Pama croaker DD (Hamilton, 1822) Perciformes Sciaenidae Panna microdon (Bleeker, 1849) Panna croaker LC Macrospinosa cuja Perciformes Sciaenidae Cuja croaker DD (Hamilton, 1822) Daysciaena albida Perciformes Sciaenidae Bengal corvina LC (Cuvier, 1830) maculatus Perciformes Sciaenidae Blotch tiger-toothed croaker LC (Cuvier, 1830) Upeneus sulphureus Cuvier, Perciformes Mullidae Sulphur goatfish* LC 1829 Grammoplites scaber Perciformes Platycephalidae Rough flathead NE (Linnaeus, 1758) Platycephalus indicus Perciformes Platycephalidae Bartail flathead DD (Linnaeus, 1758)

3.2. Taxonomic Account Distribution: From the Gulf of Aden up to the Andaman of New Records of Fishes Islands (Whitehead, 1985; Rajan et al., 2013). IUCN status: Least concern (LC). We used the following abbreviations in this section: TL- Remarks: The fish has good value. Size-180- Total length, SL-Standard length, BD-Body depth and 185 mm (SL). ex-Examples/individuals. The materials examined section 2. Sardinella fimbriata (Valenciennes, 1847). Common contains the number of individuals, the date of capture in name-Fringescale sardinella (Plate I, 2). DD-MM-YY format, the collection point and the registra- Material examined: ex 3, 18-06-2018, Point 1, ZSI F tion number. The sizes provided are of the collected indi- 12887/2. viduals. Description: Belly with a sharp keel of 31-32 scutes; 1. Sardinella longiceps Valenciennes, 1847. Common pre-pelvic-17-18, post-pelvic-14; with 1 un- name-Indian oil sardine (Plate I, 1). branched and 7 branched rays; 14 rays; 15 anal Material examined: ex 2, 19-06-2018, Point 1, ZSI F fin rays; scales with well-developed posterior median ex- 12905/2. tensions and discontinued striae; many frontoparietal striae Description: Body moderately compressed; belly with on top of head; a black spot at dorsal fin origin. a sharp keel of scutes 27-29, pre-pelvic-15-17, post-pel- Distribution: From Kuwait up to the eastern part of vic-12; pelvic fin with 1 unbranched and 8 branched rays; Papua New Guinea (Kailola, 1987; Abou-Seedo, 1992). 13 dorsal fin rays; 14-15 anal fin rays; dense frontoparietal IUCN status: Least concern (LC). striae on top of head; a distinct black spot on posterior edge Remarks: This fish has good fishery value. Size-123- of gill cover. 137 mm (SL). Ichthyofaunal integrity, hydrological and environmental features trade-off in the Sunderbans, India 15

3. Thryssa kammalensoides Wongratana, 1983. Com- IUCN status: Not evaluated (NE). mon name-Godavari thryssa (Plate I, 3). Remarks: The fish has good fishery value. Size-110 Material examined: ex 2, 19-06-2018, Point 1, ZSI F mm (TL). 12901/2. 7. Acentrogobius cyanomos (Bleeker, 1849). Common Description: Belly with 27 scutes; pre-pelvic-18, post- name-Threadfin blue goby (Plate I, 7). pelvic-9; 24-25 gill rakers on lower limb of first gill arch; Material examined: 1 ex, 19-06-2018, Point 1, ZSI F serrae, not clumped together; maxilla reaching at least to 12735/2. edge of gill cover; 32 branched anal fin rays; a dark blotch Description: Pelvic fins medially joined; cheek and on nape region extending to upper part of gill opening. opercle naked; scales cycloid on pectoral fin base and Distribution: Currently only known from Indian estua- breast, ctenoid on rest of the body; first dorsal fin with 6 rine and coastal waters (Whitehead et al., 1988; Mishra spines, second dorsal fin with 1 spine and 10 soft rays; pec- and Krishnan, 1999). toral fin with 18 rays; anal fin with 1 spine and 9 soft rays; IUCN status: Data deficient (DD). longitudinal scale series 23; pre-dorsal scales 10; presence Remarks: The fish has good fishery value. Size-108- of numerous bright pale blue spots on body and fins. 114 mm (SL). Distribution: From India up to Indonesia (Kottelat et 4. Thryssa spinidens (Jordan & Seale, 1925). Common al., 1993; Rema Devi, 1993). name-Bengal thryssa (Plate I, 4). IUCN status: Least concern (LC). Material examined: ex 2, 19-06-2018, Point 1, ZSI F Remarks: The fish has no significant fishery value. Oc- 12705/2. casionally collected in the aquarium fish trade for its col- Description: Maxilla not reaching pectoral fin base; ourful appearance. Size-80 mm (SL). belly scutes 27; pre-pelvic-16, post-pelvic-11; 13 gill rak- 8. Oxyurichthys microlepis (Bleeker, 1849). Common ers on lower arm of first gill arch; teeth enlarged; anal fin name-Maned Goby (Plate I, 8). with 3 branched and 40-41 unbranched rays; tip of snout Material examined: 1 ex, 18-06-2018, Point 1, ZSI F located at level of upper rim of eye; no black blotch on 12799/2. upper part of gill opening. Description: Pelvic fins medially joined by a simple Distribution: From India up to (Whitehead et frenum; nape with a narrow dermal crest; first dorsal fin al., 1988; Monkolprasit et al., 1997). with 6 spines; second dorsal fin with 1 spine and 12 soft IUCN status: Data deficient (DD). rays; pectoral fin with 20 rays; anal fin with 1 spine and Remarks: The fish has good fishery value. Size-135- 13 soft rays; longitudinal scale series 42; pre-dorsal scales 140 mm (SL). 14; a distinctive round black spot on upper portion of eye; 5. Scomberomorus lineolatus (Cuvier, 1829). Common many scales on nape and back have dense black-brown name-Streaked seerfish (Plate I, 5). spots on them. Material examined: 1 ex, 19-06-2018, Point 1, ZSI F Distribution: From to North-eastern Australia 12875/2. (Talwar and Jhingran, 1991; Pezold and Larson, 2015). Description: Compressed body; 8 dorsal and anal fin- IUCN status: Least concern (LC). lets; 9 gill rakers on lower limb of first gill arch; second Remarks: The fish has no significant fishery value. Oc- dorsal fin closer to caudal fin than snout; lateral line gradu- casionally collected in the aquarium fish trade for its col- ally bending downwards towards caudal keels; horizontal ourful appearance and also used as baitfish. Size-82 mm narrow black bars laterally. (SL). Distribution: From India up to Java (Allen & Smith- 9. Sphyraena jello Cuvier, 1829. Common name-Pick- Vaniz, 1994; Kapoor et al., 2002). handle barracuda (Plate I, 9). IUCN status: Least concern (LC). Material examined: 1 ex, 18-05-2018, Point 2, ZSI F Remarks: The fish has good fishery value. Size-190 12878/2. mm (SL). Description: Maxilla reaches just below anterior mar- 6. Eupleurogrammus glossodon (Bleeker, 1860). Com- gin of eye; no gill rakers on first gill arch; first dorsal fin mon name-Longtooth hairtail (Plate I, 6). with 5 spines; second dorsal fin with 1 spine and 9 soft Material examined: 1 ex, 19-06-2018, Point 1, ZSI F rays; anal fin with 2 spines and 8 soft rays; caudal fin 12873/2. forked; 138 pored lateral line scales. Description: Body tapering, ribbon-like; subopercle Distribution: Entire Indo-West Pacific (Allen and Erd- lower margin convex; eyes close to dorsal profile; tip with man, 2012). a pair of fangs; pectoral fin extending beyond lateral line; IUCN status: Not evaluated (NE). tip of each jaw with black dermal flaps. Remarks: The fish has good fishery value. Size-216 Distribution: From the Persian Gulf up to Thailand mm (SL). (Nakamura and Parin, 1993). 16 Priyankar Chakraborty, Subhrendu Sekhar Mishra, Saresh Chandra Saren, Anwesha Sengupta, Kranti Yardi

10. Solea ovata Richardson, 1846. Common name- Description: Body elongated; snout pointed; angle of Ovate sole (Plate I, 10). mouth reaching beyond lower eye, about midway between Material examined: ex 3, 29-05-2018, Point 2, ZSI F gill opening and snout tip; rostral hook short; 2 lateral lines 12833/2. on eyed side and none on blind side; scales ctenoid on eyed Description: Body ovate; BD two times in TL; snout side, cycloid on blind side; mid-lateral line with 59 scales; obtusely pointed with maxilla reaching midpoint of lower 8 scale rows between two lateral lines; 122 dorsal fin rays; eye; rostral hook short; only 1 lateral line on eyed side 73 anal fin rays; 10 caudal fin rays; eyed side uniform and none on blind side; eyes separated by a scaly concave brown in colouration. space; pectoral fin on ocular side about 1.8 times as long as Distribution: From India up to Indonesia (Mishra et one on blind side; scales ctenoid on both sides; caudal fin al., 1999; Fricke et al., 2017). separated from dorsal and anal fin; 66-68 dorsal fin rays; IUCN status: Not evaluated (NE). 45-48 anal fin rays; eyed side brown with black blotches Remarks: The fish has good fishery value. Size-132 on body and fins. mm (SL). Distribution: From India up to Indonesia (Munroe, 14. Lagocephalus guentheri Miranda Ribeiro, 1915. 2001; Kapoor et al., 2002). Common name-Diamondback puffer (Plate I, 14). IUCN status: Least concern (LC). Material examined: ex 3, 29-05-2018, Point 2, ZSI F Remarks: The fish has some fishery value. Size-58-63 12787/2. mm (SL). Description: Spinule patch on back, halfway through 11. Cynoglossus quadrilineatus (Bleeker, 1851). Com- interorbital origin to dorsal fin base; 10-12 dorsal fin rays; mon name-Fourlined tonguesole (Plate I, 11). 11-12 anal fin rays; caudal fin in fresh specimens with Material examined: 1 ex, 27-04-2018, Point 1, ZSI F slight posterior extensions (appears as doubly emarginat- 12712/2. ed), caudal fin tips white; dorsal half of body with broad Description: Body moderately elongated; rostral hook dusky bands. short; corner of mouth reaches beyond posterior of lower Distribution: From Saudi Arabia up to Japan (Matsuu- eye; 2 lateral lines on eyed side and 2 on blind side; 14 ra et al., 2011; Bogorodsky and Randall, 2018). scale rows between lateral lines on eyed side; 110 dorsal IUCN status: Least concern (LC). fin rays; 83 anal fin rays; eyed side brown with an uneven Remarks: Consumed locally in the Sundarbans black mark on gill cover. (Mishra et al., 2018). Size-53-65 mm (SL). Distribution: From Saudi Arabia up to Japan, Australia 15. Parambassis lala (Hamilton, 1822). Common (Blaber, 1980; Masuda et al., 1984; Carpenter et al., 1997). name-Hi-fin glassy perchlet (Plate I, 15). IUCN status: Least concern (LC). Material examined: 1 ex, 29-05-2018, Point 2, ZSI F Remarks: The fish has good fishery value. Size-183 12918/2. mm (SL). Description: Body deeply compressed; lower jaw long- 12. Cynoglossus semifasciatus Day, 1877. Common er than upper jaw; first dorsal fin with 6 spines, second name-Bengal tonguesole (Plate I, 12). dorsal fin with 1 spine and 12 soft rays; anal fin with 3 Material examined: 1 ex, 26-05-2018, Point 2, ZSI F spines and 15 soft rays; caudal fin forked; body brightly 12861/2. coloured with red and yellow. Description: Body elongated; snout rounded; angle of Distribution: Occurs primarily in freshwater ecosys- mouth extending a little beyond vertical from eye; rostral tems in India, and (Talwar and Jh- hook short; 2 lateral lines on eyed side and none on blind ingran, 1991; Vidthayanon et al., 2005). side; mid-lateral line with 73 scales; 12 scale rows between IUCN status: Near threatened (NT). two lateral lines; 102 dorsal fin rays; 77 anal fin rays; 10 Remarks: The fish has no significant fishery value. caudal fin rays; eyed side reddish-brown with a few faint, Size-25 mm (SL). uneven bands. 16. Gerres macracanthus Bleeker, 1854. Common Distribution: From India, and possibly Thai- name-Longspined silverbiddy (Plate I, 16). land (De Bruin et al., 1994; Monkolprasit et al., 1997; Material examined: 1 ex, 29-05-2018, Point 2, ZSI F Mishra & Krishnan, 2003). 12888/2. IUCN status: Data deficient (DD). Description: Body elongated; BD 2.7 times in SL; dor- Remarks: The fish has good fishery value. Size-160 sal fin with 9 spines and 10 soft rays; second dorsal spine mm (SL). filamentous; anal fin with 3 spines and 7 soft rays; 42 lat- 13. Cynoglossus macrolepidotus (Bleeker, 1851). Com- eral line scales; 8 indistinct vertical bands on flanks. mon name-Largescale tonguesole (Plate I, 13). Distribution: From the Red Sea up to New Guinea (We- Material examined: 1 ex, 19-06-2018, Point 1, ZSI F ber ad De Beaufort, 1931; Iwatsuki et al., 2013). 12850/2. IUCN status: Not evaluated (NE). Ichthyofaunal integrity, hydrological and environmental features trade-off in the Sunderbans, India 17

Remarks: The fish has good fishery value. Size-67 mm IUCN status: Least concern (LC). (SL). Remarks: The fish has good fishery value. Size-105- 17. Otolithes ruber (Bloch and Schneider, 1801). Com- 126 mm (SL). mon name-Tigertooth croaker (Plate I, 17). 20. Upeneus sulphureus Cuvier, 1829. Common name- Material examined: ex 2, 29-05-2018, Point 2, ZSI F Sulphur goatfish (Plate I, 20). 12728/2. Material examined: ex 5, 18-06-2018, Point 1, ZSI F Description: Body slender; mouth oblique; first dorsal 12819/2. fin with 10 spines; second dorsal fin with 1 spine and 26- Description: BD 3.2 times in SL; first dorsal fin with 28 soft rays; anal fin with 2 spines and 7 soft rays; caudal 8 spines; second dorsal fin with 1 spine and 7-8 soft rays; fin rhomboidal; 10 gill rakers on lower limb of first gill anal fin with 1 spine and 6 soft rays; scales on anal fin arch; big canine teeth on both jaws; swimbladder carrot- and second dorsal fin; barbels reach posterior margin of shaped, with 30-32 branching appendages on each side. preopercle; two narrow yellow stripes in live and freshly Distribution: From East up to Australia (van der dead specimens; no bars on caudal fin lobes. Elst, 1993; Hoese et al., 2006). Distribution: From East Africa up to Australia (Uiblein IUCN status: Least concern (LC). & Heemstra, 2010). Remarks: The fish has good fishery value. Size-112 IUCN status: Least concern (LC). mm (SL). Remarks: The fish has good fishery value. Size-59-79 18. Pennahia aneus (Bloch, 1793). Common name- mm (SL). Donkey croaker (Plate I, 18). Material examined: ex 2, 29-05-2018, Point 2, ZSI F 3.3. Environmental Parameters 12903/2. Description: Mouth large; teeth large and small in both Water quality parameters (Table 2) displayed strong evi- jaws; 9 spines on first dorsal fin; second dorsal fin with 1 dence of tidal incursion, with considerable freshwater spine and 22 soft rays; anal fin with 2 spines and 7 soft influence due to monsoonal discharge in the Sundar- rays; 11 gill rakers on lower limb of first gill arch; caudal bans delta. We observed moderately high salinity (mean: fin truncate; swimbladder carrot-shaped, with 17 branched 1.011-1.017) and moderately high dissolved oxygen appendages along its sides. (mean: 9.6-10.1). The average water pH was slightly al- Distribution: From the Persian Gulf up to Taiwan (Sa- kaline and was relatively constant among the two sites, saki, 2001). ranging between 7.4 and 8.2. We measured higher salinity IUCN status: Least concern (LC). at point 1. Remarks: The fish has good fishery value. Size-71-109 mm (SL). 3.4. Diversity Status 19. Johnius carouna (Cuvier, 1830). Common name- Caroun croaker (Plate I, 19). The values of Shannon Wiener index (H), evenness (E) and Material examined: ex 3, 29-05-2018, Point 2, ZSI F Simpson’s diversity index (1-D) for both communities are 12900/2. shown in Figures 3-5. Description: Mouth small, inferior; first dorsal fin with Community 1 has a Shannon-Wiener index value 10 spines; second dorsal fin with 1 spine and 29-30 soft of 3.94 and evenness of 0.830, while community 2 has rays; anal fin with 2 spines and 7 soft rays; 14 gill rakers a Shannon index of 3.72 and evenness of 0.832. The ENS on lower limb of first gill arch; caudal fin rhomboidal; calculated from the Shannon indices are 51 for community swimbladder hammer-shaped, with 14-15 branching ap- 1 and 41 for community 2, meaning community 1 is 1.24 pendages on each side. times more diverse than community 2. Community 1 has Distribution: From India up to Southern (Talwar, a Simpson’s diversity index of 0.979, while community 1995; Sasaki, 2001).

Table 2. Mean and standard deviation values of environmental parameters of the two collection points (April 2018-June 2018).

Dissolved oxygen Water Secchi Depth Collection Point Salinity pH (mg L−1) temperature (˚C) (inches)

Point 1 1.017 ± 2.2 9.6 ± 5.7 8.2 ± 3.4 24.3 ± 1.3 36.1 ± 4.8 Point 2 1.011 ± 1.7 10.1 ± 2.6 7.4 ± 1.4 25.5 ± 2.8 38.3 ± 1.6 18 Priyankar Chakraborty, Subhrendu Sekhar Mishra, Saresh Chandra Saren, Anwesha Sengupta, Kranti Yardi

DissolvedDissolved WaterWater CollectionCollection SecchiSecchi DepthDepth 2 has 0.973. The value ofSalinity Sorenson’s coefficientoxygen of com(mg- gesting thatpH the richness andtemperature evenness of community 1 are Point Salinity oxygen (mg pH temperature (inches) Point −1 (inches) munity is 0.87. L −1) more than that of community (2,˚C) which has a value of 3.72. L ) However, these two values are( ˚justC) indices. To effectively Point 1 1.017 ± 2.2 9.6 ± 5.7 compare8.2 ± 3.4 species diversity,24.3 we ± calculated1.3 the 36.1effective ± 4.8 num - Point 1 1.017 ± 2.2 9.6 ± 5.7 8.2 ± 3.4 24.3 ± 1.3 36.1 ± 4.8 Point 2 4.1.011 Discussion ± 1.7 10.1 ± 2.6 ber7.4 of ±species. 1.4 We found25.5 that ± community2.8 1 38.3has a ± value 1.6 of Point 2 1.011 ± 1.7 10.1 ± 2.6 51,7.4 which ± 1.4 is 1.24 times25.5 more ± than 2.8 the ENS of38.3 community ± 1.6 The Shannon-Wiener diversity measure comes from infor- 2, 41. The evenness values show that both communities 335 335 mation theory (Rissanen, 1997). It measures the number3.4.3.4. DiversityDiversity of are pretty StatusStatus even (community 1: 0.830, community 2: 0.832) 336 individualsThe values observed of Shannon for each species Wiener in aindex sample (H),area. Inevenness with a slight(E) anddifference. Simpson's diversity index (1-D) for 336 thisThe study, values community of Shannon 1 has a Shannon Wiener index index of 3.94, (H), sug evenness- (E) and Simpson's diversity index (1-D) for 337337 bothboth communitiescommunities areare shownshown inin FiguresFigures 33--5.5.

338338 339339 Figure 3. TheFigureFigure Shannon-Wiener 3.3. TheThe ShannonShannon index (H)- -WienerofWiener community indexindex 1 = (H)(H)3.94 ofandof community communitycommunity 2 = 11 3.72. == 3.943.94 andand communitycommunity 22 == 3.723.72..

340340 Figure 4. The evenness (E) of community 1 = 0.830 and community 2 = 0.832. 341341 FigureFigure 4.4. TheThe evennessevenness (E(E)) ofof communitycommunity 11 == 0.8300.830 andand communitycommunity 22 == 0.8320.832.. Ichthyofaunal integrity, hydrological and environmental features trade-off in the Sunderbans, India 19

A modified scale of pollution represented in terms of fish, Oreochromis mossambicus, is an invasive species in species diversity shows a negative correlation between the India (Ganie et al., 2013). However, it faces extirpation in Shannon index and pollution (Staub et al., 1970). Accord- its native range (Zengeya et al., 2015). ing to its range, both communities in our study are only We have provided only those assessments that are based marginally polluted. globally. The basis of some categorizations in the IUCN Simpson’s index for community 1 is 0.979. It has Red List are regional assessments (e.g., Eleutheronema a slightly greater value when compared to community 2, tetradactylum assessed to be endangered (Motomura et whose value is 0.973. However, the indices of both com- al., 2015), based on studies from the Persian Gulf). So, the munities suggest decent species diversity at both points. applicability of such assessments for Indian Sundarbans The coefficient of community value of 0.87 signifies remains to be ground-truthed. There is an urgent need to a good deal of similarity in species between two points assess the status of the not evaluated fishes in the Indian (a value of 1 suggests a complete overlap of species be- Sundarbans, as they are collected regularly for human con- tween the communities). sumption and sale. There exists a significant correlation of mangrove for- We recommend being mindful about the terms: Data est attributes (natural, degraded and replanted) with estua- deficient (DD) and Not evaluated (NE). One must never rine fish and species diversity (Crona and Ron- synonymize them with the category of Least Concern (LC). nback, 2005; Manson et al., 2005; Sandoval Londoño et There is an equal threat of extinction for species that cur- al., 2020). Therefore, we hypothesize that fewer man- rently falls in the DD and NE categories. We have graphi- groves and the presence of anthropogenic pressures could cally represented the number of fishes and their respective be the reason community 2 has a relatively less number of conservation categories (Figure 6). All species reported in species. Its location near the village of Amlamethi in Bally- this study are economically significant and locally con- I island could be why it has less mangrove cover and faces sumed, even Tetraodontiformes (Mishra et al., 2018). human-related pressures. Pneumatophores and prop roots of the mangrove trees, We have provided the respective IUCN statuses for all along with their fallen branches and leaves, make a com- the fishes we have listed. In our collection, we found two plex habitat for a host of prey organisms, forming an fish species-Harpadon nehereus and Parambassis lala, be- important food source for many fish species (Verweij et longing to the conservation category near threatened (NT). al., 2006). Therefore, mangroves form a core fish habitat We also found two species-Tenualosa toli, Oreochromis in tropical estuaries and lagoons (Blaber, 2007). mossambicus belonging to the vulnerable (VU) category. A total of 20 fish species were recorded for the first All four species face a risk of extinction in the wild. Others time from the Indian Sundarbans during this study. It effec- mainly fell into the least concern (LC), not evaluated (NE), tively brings the total number of fish species recorded from and data deficient (DD) categories. One of the vulnerable the region to 378. Some of the newly documented fishes

342 343 FigureFigure 5. IUCNThe conservationSimpson's status index of the of fishes diversity collected (1during-D) the values study of community 1 = 0.979 and community 2 = 344 0.973. 345 Community 1 has a Shannon-Wiener index value of 3.94 and evenness of 0.830, while 346 community 2 has a Shannon index of 3.72 and evenness of 0.832. The ENS calculated from the 347 Shannon indices are 51 for community 1 and 41 for community 2, meaning community 1 is 1.24 348 times more diverse than community 2. Community 1 has a Simpson's diversity index of 0.979, 349 while community 2 has 0.973. The value of Sorenson's coefficient of community is 0.87. 350 4. Discussion 351 The Shannon-Wiener diversity measure comes from information theory (Rissanen, 1997). It 352 measures the number of individuals observed for each species in a sample area. In this study, 353 community 1 has a Shannon index of 3.94, suggesting that the richness and evenness of 354 community 1 are more than that of community 2, which has a value of 3.72. However, these two 355 values are just indices. To effectively compare species diversity, we calculated the effective 356 number of species. We found that community 1 has a value of 51, which is 1.24 times more than 357 the ENS of community 2, 41. The evenness values show that both communities are pretty even 358 (community 1: 0.830, community 2: 0.832) with a slight difference. 359 A modified scale of pollution represented in terms of species diversity shows a negative 360 correlation between the Shannon index and pollution (Staub et al., 1970). According to its range, 361 both communities in our study are only marginally polluted. 20 Priyankar Chakraborty, Subhrendu Sekhar Mishra, Saresh Chandra Saren, Anwesha Sengupta, Kranti Yardi

are also first records from West Bengal, e.g., Thryssa kam- Indian Sundarbans (Chakraborty, et al. 2018). It probably malensoides, Scomberomorus lineolatus, Lagocephalus got overlooked in previous surveys from the Indian Sunda- guentheri, and others rbans. Salinity plays a significant role in the distribution of The presence of Thryssa kammalensoides in the Sunda- marine and fishes, and long term variations rbans is intriguing as this species was previously only re- in salinity can affect fish species distribution (Cyrus and corded from the coastal waters of the neighbouring state Blaber, 1992). In many studies, catch rates of abundant of Odisha, with a northern limit up to Chandipur in the species correlated strongly with salinity patterns (Barlet- Balasore district (Mishra and Krishnan, 1999). ta et al., 2005; Lugendo et al., 2007). We recorded salin- We suspect foraging to be a reason behind the occur- ity only during sampling and not during other times. Such rence of T. kammalensoides in the region. Both the quantity discrepancy disallows from accurately correlating salinity and type of food found in mangrove areas are different with fish distribution within the scope of this study. The from adjacent marine areas. Many of the microflora and need to collect environmental data consistently over a more fauna found in the sheltered mangroves are not present prolonged period is necessary. We hypothesize tidal incur- in offshore waters. Therefore, there is an increase in the sion to have a role to play in the distribution of the newly diversity and quantity of food available to fishes in the recorded fishes. mangroves (Robertson and Duke, 1990). The availability Abiotic factors like turbidity may also play a role in the of T. kammalensoides in Sundarbans may be correlated to presence of fish species absent earlier. Since turbidity is the availability of its food source. usually high in the mangrove region, it reduces the visual We recorded almost all freshwater fish species from capacity of large predators. The shallow waters exclude community 2. The mean value of salinity of community 2 large predatory fishes from entering them, helping smaller is considerably less than that of community 1. The collec- fish to take shelter and thrive in the creeks around man- tion point was very close to an island with several fresh- groves (Cyrus and Blaber, 1987). The mean visible depth water outlets, and there was the added freshwater influx of of both the collecting points was almost similar (point the monsoons. We believe that those reasons could have 1-36”, point 2-38”). allowed for the survival of freshwater fishes in the collec- Another possible explanation of why we found these tion point. previously unreported fishes could be because they prob- Seasonal variations in nutrients affect the coexistence ably escaped the attention of science. It could be due to of many fish species (Huh andFigure Kitting, 1985). The inadequate sampling or incorrect . For exam- first author noted a large number of small shrimps getting ple, a newly described Moray eel: Gymnothorax pseudo- caught in each haul. There could be a relation between tile Mohapatra, Smith, Ray, Mishra & Mohanty, 2017 was the high incidences of these with observed considered a marine fish until its recent report from the fish species. Some fishes were found when the salinity

80 70

60 50 40 30 20 Number fishes of Number 10 0

Conservation categories (IUCN) 393 Figure 6. IUCN status of the fishes collected during the study (NE-22, DD-16, LC-70, NT-2, and VU-2). 394 Figure 6. IUCN status of the fishes collected during the study (NE-22, DD-16, LC-70, NT-2, and VU-2).

395 Pneumatophores and prop roots of the mangrove trees, along with their fallen branches 396 and leaves, make a complex habitat for a host of prey organisms, forming an important food 397 source for many fish species (Verweij et al., 2006). Therefore, mangroves form a core fish 398 habitat in tropical estuaries and lagoons (Blaber, 2007). 399 A total of 20 fish species were recorded for the first time from the Indian Sundarbans 400 during this study. It effectively brings the total number of fish species recorded from the region 401 to 378. Some of the newly documented fishes are also first records from West Bengal, 402 e.g., Thryssa kammalensoides, Scomberomorus lineolatus, Lagocephalus guentheri, and others 403 Salinity plays a significant role in the distribution of marine and brackish water fishes, 404 and long term variations in salinity can affect fish species distribution (Cyrus and Blaber, 1992). 405 In many studies, catch rates of abundant species correlated strongly with salinity patterns 406 (Barletta et al., 2005; Lugendo et al., 2007). We recorded salinity only during sampling and not 407 during other times. Such discrepancy disallows from accurately correlating salinity with fish 408 distribution within the scope of this study. The need to collect environmental data consistently 409 over a more prolonged period is necessary. We hypothesize tidal incursion to have a role to play 410 in the distribution of the newly recorded fishes. 411 Abiotic factors like turbidity may also play a role in the presence of fish species absent 412 earlier. Since turbidity is usually high in the mangrove region, it reduces the visual capacity of 413 large predators. The shallow waters exclude large predatory fishes from entering them, helping Ichthyofaunal integrity, hydrological and environmental features trade-off in the Sunderbans, India 21

of a point was considerably higher. For example, in com- Andharia J., 2020, A Web of Vulnerabilities: Eco-fragility, munity 2, the fishers caught the Pickhandle barracuda on Poor Livelihoods and Cyclones in Sundarban Region, a day when the salinity was-1.019. The environmental pa- India, [in:] Disaster Studies, J. Andharia (ed.), Springer, rameters provide some insights into the ecology of the : 357-374. doi: https://doi.org/10.1007/978- fishes. 981-32-9339-7_17 Barik J. & Chowdhury S., 2014, True Mangrove Species of Sundarbans Delta, West Bengal, Eastern India: A Re- 5. Conclusions vised Species List. Check List 10(2): 329-334. doi: htt- ps://doi.org/10.15560/10.2.329 In this study, we found the fish composition from both Barletta M., Barletta-Bergen A., Saint-Paul U. & Hubold communities to be moderately distinct from each other. G., 2005, The role of salinity in structuring the fish as- The Shannon values indicate that both communities are semblages in a tropical estuary. Journal of Fish Biol- high in species richness and evenness. No particular spe- ogy 66(1): 45-72. doi: https://doi.org/10.1111/j.0022- cies dominate the communities. The true diversity values 1112.2005.00582.x reveal that community 1 is 1.24 times as diverse in fish Blaber S.J.M., 1980, Fish of Trinity Inlet system of north species as community 2. A high Simpson’s index indicates with notes on the ecology of fish faunas of that both communities are considerably diverse. All the tropical Indo-Pacific estuaries. Marine and Freshwater values are indicative of the overall good health of the sur- Research 31(2): 137-146. rounding ecosystem. Blaber S.J.M., 2007, Mangroves and fishes: issues of diver- We recorded a total of 20 fish species from the man- sity, dependence, and dogma. Bulletin of Marine Sci- groves for the first time, bringing the total number of fishes ence 80(3): 457-472. recorded from the Indian Sundarbans to 378. Some are Bogorodsky S.V. & Randall J.E., 2018, Endemic fishes of even new records from West Bengal, India. The Indian the Red Sea, [in:] Oceanographic and biological aspects Sundarbans is a highly variable region, and its variabil- of the Red Sea, N.M.A. Rasul & I.C.F. Stewart (eds.), ity affects the ever-changing ichthyofauna residing in its Springer Oceanography, Basel: 239-265. brackish waters. The present study is a baseline study for Brinda S., Srinivasan M., Balakrishnan S., 2010, Studies on only three months. We believe that long term monitoring to diversity of finfish larvae in Vellar estuary, Southeast assess the distribution and abundance of the ichthyofaunal coast of India. World Journal of Fish and Marine Sci- diversity of Sundarbans is crucial, especially the responses ences 2(1): 44-50. to climate change. Carpenter K.E., Krupp F., Jones D.A. & Zajonz U., 1997, Species identification guide for fishery purposes. The living marine resources of Kuwait, eastern Saudi Ara- Acknowledgements bia, Bahrain, Qatar, and the United Arab Emirates. FAO, Rome: 239. The authors would like to thank Dr Kailash Chandra, di- Chakraborty P., Saren S.C., Sengupta A. & Mishra S.S., rector of the Zoological Survey of India (ZSI), Kolkata, 2018, Notes on the record of Gymnothorax pseudotile India and Dr L. Kosygin Singh, scientist-D, Fish Division, Mohapatra et al., 2017 (Muraenidae: Muraeninae) from ZSI, Kolkata, India, for providing permission and working the Sundarbans, West Bengal, India. Records of Zoo- facilities. The first author would like to thank Dr Erach logical Survey of India 118(3): 318-321. doi: 10.26515/ Bharucha, director of BVIEER, Pune, India and Prof Dr rzsi/v118/i3/2018/121639 Shamita Kumar, vice-principal of BVIEER, Pune, India, Crona B.I. & Ronnback P., 2005, Use of replanted man- for supporting the first author. groves as nursery grounds by shrimp communities in Gazi Bay, Kenya. Estuarine Coastal and Shelf Sci- ence 65(3): 535-544. doi: https://doi.org/10.1016/j. References ecss.2005.07.001 Cyrus D.P. & Blaber S.J.M., 1987, The influence of turbidity Abou-Seedo F.S., 1992, Abundance of fish caught by stake- on juvenile marine fish in the estuaries of Natal, South traps (hadra) in the intertidal zone in Doha, Kuwait Bay. Africa. Continental Shelf Research 7(11/12): 1411-1416. Journal of the University of Kuwait 19: 91-99. doi: https://doi.org/10.1016/0278-4343(87)90046-X Allen G.R. & Erdmann M.V., 2012, Reef fishes of the East Cyrus D.P. & Blaber S.J.M., 1992, Turbidity and salinity Indies, volumes I-III. Tropical Reef Research, Perth: in a tropical northern Australian estuary and their influ- 1260. ence on fish distribution. Estuarine, Coastal and Shelf Allen G.R. & Smith-Vaniz W.F., 1994, Fishes of the Cocos Science 35(6): 545-563. doi: https://doi.org/10.1016/ (Keeling) Islands. Atoll Research Bulletin 412: 1-21. S0272-7714(05)80038-1 22 Priyankar Chakraborty, Subhrendu Sekhar Mishra, Saresh Chandra Saren, Anwesha Sengupta, Kranti Yardi

Darwall W.R.T. & Vie´ J.C., 2005, Identifying important Kapoor D., Dayal R., Ponniah A.G., 2002, Fish biodiversity sites for conservation of freshwater biodiversity: ex- of India. National Bureau of Fish Genetic Resources, tending the species-based approach. Man- Lucknow: 775. agement and Ecology 12(5): 287-293. doi: https://doi. Karr J.R., 1981, Assessment of biotic integrity using fish org/10.1111/j.1365-2400.2005.00449.x communities. Fisheries 6(6): 21-27. doi: https://doi. De Bruin G.H.P., Russell B.C., Bogusch A., 1994, Spe- org/10.1577/1548-8446(1981)006<0021:AOBIUF>2.0. cies identification guide for fishery purposes. The CO;2 marine fishery resources of Sri Lanka. FAO, Rome: Kottelat M., Whitten A.J., Kartikasari S.N. & Wirjoatmodjo 400. S., 1993, Freshwater fishes of Western Indonesia and Fricke R., Eschmeyer W.N., Van der Laan R., (eds.), 2021, Sulawesi. Periplus Editions, : 259. ESCHMEYER’S CATALOG OF FISHES: GENERA, Lugendo B.R., de Groene A., Cornelissen I., Pronker A., SPECIES, REFERENCES. California Academy of Sci- Nagelkerken I., van der velde G. & Mgaya Y.D., 2007, ences, San Francisco, CA, USA. http://researcharchive. Spatial and temporal variation in fish community struc- calacademy.org/research/ichthyology/catalog/fishcat- ture of a marine embayment in Zanzibar, Tanzania. Hy- main.asp [electronic version, Accessed 22 February drobiologia 586(1):1-16. 2021]. Manson F.J., Loneragan N.R., Skilleter G.A. & Phinn S.R., Fricke R., Golani D., Appelbaum-Golani B., 2017, Cyno- 2005, An evaluation of the evidence for linkages between glossus crepida, a new species of tongue sole from the mangroves and fisheries: a synthesis of the literature and Gulf of Aqaba, Red Sea (Teleostei: Cynoglossidae). identification of research directions. Oceanography and Journal of the Ocean Science Foundation 25: 77-87. -An Annual Review 43: 483-513. FSI, 2019, India State of Forest Report. Forest Survey of Marzluff J.M. & Ewing K., 2008, Restoration of Fragment- India, Dehradun: 183. ed Landscapes for the Conservation of Birds: A Gen- Ganie M.A., Bhat M.D., Khan M.I., Parveen M., Balkhi eral Framework and Specific Recommendations for Ur- M.H. & Malla M.A., 2013, Invasion of the Mozam- banizing Landscapes, [in:] Urban Ecology, J.M. Mar- bique tilapia, Oreochromis mossambicus (Pisces: Cich- zluff et al. (eds.), Springer, Boston, MA: 739-755. doi: lidae; Peters, 1852) in the Yamuna river, Uttar Pradesh, https://doi.org/10.1007/978-0-387-73412-5_48 India. Journal of Ecology and the Natural Environment Masuda H., Amaoka K., Araga C., Uyeno T. & Yoshino T., 5(10): 310-317. 1984, The Fishes of the Japanese Archipelago, volume Hammer Ø., Harper D.A.T., Ryan P.D., 2001, PAST: Pale- 1. Tokai University Press, Tokyo: 437. ontological statistics software package for education Matsuura K., Golani D., Bogorodsky S.V., 2011, The first and data analysis. Palaeontologia electronica 4(1): 1-9. record of Lagocephalus guentheri Miranda Ribeiro, Hoese D.F., Bray D.J., Paxton J.R. & Allen G.R., 2006, 1915 from the Red Sea with notes on previous records Fishes, [in:] Zoological Catalogue of Australia, volume of L. lunaris (Actinopterygii, Tetraodontiformes, Tetrao- 35, O.L. Beasley & A. Wells (eds.), ABRS & CSIRO dontidae). Bulletin of the National Museum of Nature Publishing, Australia: 1-2178. and Science, Series A 37(3): 163-169. Huh S.H. & Kitting C.L., 1985, Trophic relationships Mishra S.S. & Krishnan S., 1999, On the occurrence of among concentrated populations of small fishes in Thryssa kammalensis (Bleeker) and Thryssa kam- seagrass meadows. Journal of Experimental Marine malensoides Wongratana (Engraulididae: Pisces) from Biology and Ecology 92(1): 29-43. doi: https://doi. India. Records of Zoological Survey of India 97(3/4): org/10.1016/0022-0981(85)90020-6 109-111. IUCN, 2021, The IUCN Red List of Threatened Species. Mishra S.S. & Krishnan S., 2003, Marine fishes of Pondi- Version 2021-1. https://www.iucnredlist.org Download- cherry and Karaikal. Records of the Zoological Survey ed on [09 February 2021]. of India, Occasional Paper No. 216: 1-52. Iwatsuki Y., Jawad L.A., Tanaka F., Al-Busaidi H., Mishra S.S., Chakraborty P., Saren S.C. & Sengupta A., Al-Mamry J.M. & Al-Kharusi L.H., 2013, Omani fish- 2018, First record of Lagocephalus guentheri Miranda es collected in the vicinity of Mutrah, Gulf of Oman Riberio 1915 (Tetraodontiformes: Tetraodontidae) from and Madrakah, southern Oman through 3 to 13 October the West Coast of India. Records of Zoological Survey 2010. Bulletin of the Faculty of Agriculture, University of India 118(1): 91-96. doi: https://doi.org/10.26515/ of Miyazaki 59: 29-41. rzsi/v118/i1/2018/122386 Kailola P.J., 1987, The fishes of Papua New Guinea. A re- Mishra S.S., Gopi K.C., 2017, Fish diversity of Indian vised and annotated checklist, volume I: Myxinidae Sundarbans and its resources and research prospects, to Synbranchidae. Research Bulletin No. 41. Depart- [in:] Fauna of Sundarbans Biosphere Reserve, K. Chan- ment of Fisheries and Marine Resources, Port Moresby: dra et al. (eds.), Zoological Survey of India, Kolkata: 194. 107-127. Ichthyofaunal integrity, hydrological and environmental features trade-off in the Sunderbans, India 23

Mishra S., Gouda R., Nayak L. & Panigrahy R.C., 1999, bia). Bulletin of Marine Science 96(3): 415-429. doi: A check list of the marine and estuarine fishes of south https://doi.org/10.5343/bms.2019.0022 Orissa, east coast of India. Records of the Zoological Sarkar S.K. & Bhattacharya A.K., 2003, Conservation of Survey of India 97(3): 81-90. biodiversity of the coastal resources of Sundarbans, Monkolprasit S., Sontirat S., Vimollohakarn S. & Songsiri- Northeast India: an integrated approach through envi- kul T., 1997, Checklist of Fishes in Thailand. Office of ronmental education. Marine Pollution Bulletin 47(1/6): Environmental Policy and Planning, Bangkok: 353. 260-264. doi: 10.1016/s0025-326x(02)00475-7 Motomura H., Matsuura K., Bishop J. & Kaymar- Sasaki K., 2001, Family Sciaenidae, [in:] Species identi- am F., 2015, Eleutheronema tetradactylum. The fication guide for fishery purposes. The living marine IUCN Red List of Threatened Species 2015: resources of the western central Pacific, volume 6. Bony e.T46087646A57168342. Downloaded on 09 April fishes part 4 (Labridae to Latimeriidae), estuarine croco- 2021. diles, sea turtles, sea snakes and marine mammals, K.E. Munroe T.A., 2001, Families Soleidae, [in:] Species iden- Carpenter & V.H. Niem (eds.), FAO, Rome: 2791-3380. tification guide for fishery purposes. The living marine Smith-Vaniz W.F., 1999, Family Carangidae, [in:] Species resources of the western central Pacific, volume 6. Bony identification guide for fishery purposes. The living ma- fishes part 4 (Labridae to Latimeriidae), estuarine croco- rine resources of the western central Pacific, volume 4. diles, sea turtles, sea snakes and marine mammals, K.E. Bony fishes part 2 (Mugilidae to Carangidae), K.E. Car- Carpenter & V.H. Niem (eds.), FAO, Rome: 3878-3889. penter & V.H. Niem (eds.), FAO, Rome: 2659-2756. Nakamura I. & Parin N.V., 1993, FAO species catalogue. Staub R., Appling J.W., Hofstetter A.M. & Haas I.J., 1970, Snake mackerels and cutlassfishes of the world (Fam- The effects of industrial wastes of Memphis and Shelby ilies and Trichiuridae). An annotated and County on primary planktonic producers. BioScience illustrated catalogue of the snake mackerels, snoeks, 20(16): 905-912. escolars, gemfishes, sackfishes, domine, oilfish, cut- Talwar P.K. & Jhingran A.G., 1991, Inland fishes of India lassfishes, scabbardfishes, hairtails, and frostfish- and adjacent countries, volumes I-II. Oxford & IBH es known to date. FAO Fisheries Synopsis 125(15): Publishing Co., New Delhi, Bombay, Calcutta: 1158. 1-136. Talwar P.K., 1995, Fauna of India and adjacent countries: Padhy S.R., Bhattacharyya P., Dash P.K., Reddy C.S., Pisces, Perciformes: Sciaenidae. Zoological Survey of Chakraborty A. & Pathak H., 2020, Seasonal fluctua- India, Kolkata: 144. tion in three mode of greenhouse gases emission in re- Uiblein F. & Heemstra P.C., 2010, A taxonomic review lation to soil labile carbon pools in degraded mangrove, of the Western goatfishes of the Sundarban, India. The Science of the total environ- Upeneus (Family Mullidae), with descriptions of four ment 705: 135909. doi: https://doi.org/10.1016/j.scito- new species. Smithiana Bulletin 11: 35-71. tenv.2019.135909 Van der Elst R., 1993, A guide to the common sea fishes of Pezold F.L. & Larson H.K., 2015, A revision of the fish southern Africa, 3rd ed. Struik Publishers, Cape Town: genus Oxyurichthys (Gobioidei: Gobiidae) with descrip- 398. tions of four new species. Zootaxa 3988(1): 1-95. Van der Laan R., Fricke R., Eschmeyer W.N., (eds.), Rajan P.T., Sreeraj C.R., Immanuel T., 2013, Fishes of An- 2021, ESCHMEYER’S CATALOG OF FISHES: CLAS- daman, Andaman and Nicobar Islands: a checklist. Jour- SIFICATION. (http://www.calacademy.org/scientists/ nal of Andaman Science Association 18(1): 47-87. catalog-of-fishes-classification/). [electronic version, Rema Devi K., 1993, Gobioids of Ennore Estuary and its Accessed 12 February 2021]. vicinity. Records of the Zoological Survey of India Verweij M.C., Nagelkerken I., de Graaf D., Peeters M., Bak- 90(1/4): 161-189. ker E.J. & van der Velde G., 2006, Structure, food and Rissanen J., 1997. Shannon-Wiener information and sto- shade attract juvenile coral reef fish to mangrove and chastic complexity, [in:] Proceedings of the Norbert seagrass habitats: a field experiment. Marine Ecology Wiener centenary congress on Norbert Wiener centenary Progress Series 306: 257-268. congress (NWCC ‘94), V. Mandrekar & P.R. Masani Vidthayanon C., Termvidchakorn A., Pe M., 2005, Inland (eds.), AMS Press, Inc., New York: 331-341. fishes of Myanmar. Southeast Asian Fisheries Develop- Robertson A.I. & Duke N.C., 1990, Mangrove fish commu- ment Center, Bangkok: 160. nities in tropical Australia: spatial and temporal patterns Weber M. & De Beaufort L.F., 1931, The fishes of the Indo- in densities, biomass and community structure. Marine Australian Archipelago, volume VI. Perciformes: Ser- Biology 104: 369-379. ranidae, Theraponidae, Sillaginidae, Emmelichthyidae, Sandoval Londoño L.A., Leal-Flórez J., Blanco-Libreros Bathyclupeidae, Coryphaenidae, Carangidae, Rachycen- J.F., 2020, Linking mangroves and fish catch: a cor- tridae, Pomatomidae, Lactariidae, Menidae, Leiognathi- relational study in the southern Caribbean Sea (Colom- dae, Mullidae. E.J. Brill Ltd., Leiden: 448. 642 and wolf-herrings, Part 1: Chirocentridae, Clupeidae and Pristigasteridae. FAO Fisheries 643 Synopsis 125(7): 113–114. 644 642Whitehead P.J.P.,and wolfNelson-herrings, G.J., WongratanaPart 1: Chirocentridae, T., 1988, FAOClupeidae species and catalogue. Pristigasteridae. Clupeoid FAO fishes Fisheries of the 642 and wolf-herrings, Part 1: Chirocentridae, Clupeidae and Pristigasteridae. FAO Fisheries 645 643 world (SuborderSynopsis 125 Clupeoidei).(7): 113–114. An annotated and illustrated catalogue of the herrings, sardines, 642642642 andandand wolfwolfwolf--herrings,-herrings,herrings, PartPart 1:1: Chirocentridae,Chirocentridae, ClupeidaeClupeidae andand Pristigasteridae.Pristigasteridae. FAO FAO FisheriesFisheries 643642642 Synopsisandand wolfwolf 125--herrings,herrings,(7): 113 –PartPart114. 1:1: Chirocentridae,Chirocentridae, ClupeidaeClupeidae andand Pristigasteridae.Pristigasteridae. FAOFAO FisheriesFisheries 644 Whitehead24 Priyankar P.J.P., Chakraborty, Nelson G.J., Subhrendu Wongratana Sekhar Mishra, T., Saresh 1988, Chandra FAO Saren, species Anwesha catalogue. Sengupta, Clupeoid Kranti Yardi fishes of the 646 643643643 pilchards, SynopsisSynopsisSynopsis sprats, 125 125125 shads,(7):(7):(7): 113 113113 anchovies,––114.114. and wolf-herrings, Part 2: Engraulididae. FAO Fisheries 644643643 Whitehead SynopsisSynopsis P.J.P., 125125 Nelson(7):(7): 113113 G.J.,––114.114. Wongratana T., 1988, FAO species catalogue. Clupeoid fishes of the 647 645 Synopsisworld 125 (Suborder(7/2): 305 –Clupeoidei).579. An annotated and illustrated catalogue of the herrings, sardines, 645644644644644 WhiteheadWhiteheadWhiteheadWhiteheadworld P.J.P., P.J.P., P.J.P.,(Suborder NelsonNelsonNelson Clupeoidei). G.J.,G.J., WongratanaWongratana An annotated T.,T., 1988,1988, and FAOillustratedFAO speciesspecies catalogue catalogue.catalogue. of ClupeoidClupeoidtheClupeoid herrings, fishesfishesfishes sardines, ofofof thethethe 646644 Whiteheadpilchards, P.J.P., sprats, Nelson shads, G.J., Wongratanaanchovies, and T., 1988,wolf- herringsFAO species, Part catalogue. 2: Engraulididae. Clupeoid FAOfishes Fisheriesof the 645 Welcommeworld R.L., (Suborder Winemiller Clupeoidei).K.O., Cowx I.G., An 2006,annotated Fish andWhitehead illustrated P.J.P., catalogue Nelson G.J., of theWongratana herrings, T., sardines,1988, FAO 648 646645645645Zengeya T.A.,pilchards,worldworldworld Booth (Suborder(Suborder(Suborder A.J.,sprats, Chimimba Clupeoidei).Clupeoidei).shads, anchovies, C.T AnAn., annotated annotated2015, and wolfBroad andand-herrings nicheillustratedillustrated ,overlap Part cataloguecatalogue 2: between Engraulididae. ofof the thetheinvasive herrings,herrings,herrings, FAO Nile sardines,sardines,Fisheriessardines, tilapia 647645 environmentalSynopworldsis (Suborder guilds 125 (7/2):as a toolClupeoidei). 305 for– assessment579. An ofannotated ecologi- and illustratedspecies catalogue. catalogue Clupeoid of the fishes herrings, of the worldsardines, (Sub - 646646 pilchards,pilchards, sprats,sprats, shads,shads, anchovies,anchovies, andand wolfwolf--herringsherrings,, PartPart 2:2: Engraulididae.Engraulididae. FAO Fisheries 649 647 646646 Oreochromis cal conditionSynoppilchards,pilchards,sis of niloticus 125rivers. sprats,sprats,(7/2): River and shads,305shads, Research indigenous–579. anchovies,anchovies, and Applications congenerics andand wolf -herrings in orderSouthern ,Clupeoidei). Part Africa:2: Engraulididae. An Should annotated we and FAOFAO be illustrated concerned? FisheriesFisheries cata - 648646 Zengeyapilchards, T.A., Booth sprats, A.J., shads, Chimimba anchovies, C.T and., 2015, wolf Broad-herrings niche, Part overlap 2: Engraulididae. between invasive FAO Nile Fisheries tilapia 647647647 22(3):Synop SynopSynop377-396.sississis doi:125 125125 (7/2):https://doi.org/10.1002/rra.914(7/2):(7/2): 305305––579.579. logue of the herrings, sardines, pilchards, sprats, shads, 650 648647647 Whitehead ZengeyaSynop Synop P.J.P.,T.A.,sissis 1985,Booth Entropy 125125 (7/2):(7/2):FAO A.J., 17(7): species 305305 Chimimba––579.579. 4959catalogue. – 4973.C.T Clupeoid., 2015,doi: https://doi.org/10.3390/e17074959 Broadanchovies, niche overlap and betweenwolf-herrings, invasive Part Nile2: Engraulidi tilapia - 649648648648 ZengeyaZengeyaZengeyaOreochromis T.A., T.A.,T.A., Booth BoothBooth niloticus A.J.,A.J., ChimimbaChimimba and indigenous C.TC.T.,., 2015,2015,congenerics BroadBroad nichenichein Southern overlapoverlap Africa: betweenbetweenbetween Should invasiveinvasive we Nile Nilebe concerned? tilapia tilapia 651 649648 ZengeyafishesOreochromis of theT.A., world Booth (Suborder niloticus A.J., Clupeoidei). Chimimba and indigenous An C.T annotated., congenerics 2015, Broad indae. niche Southern FAO overlap Fisheries Africa: between Synopsis Should invasive 125(7/2): we be Nile concerned?305-579. tilapia 648 Zengeyaand illustrated T.A., catalogue Booth A.J., of the Chimimba herrings, sardines, C.T., 2015, pil- BroadZengeya niche T.A., overlap Booth between A.J., Chimimba invasive C.T., Nile 2015, tilapia Broad 650649649649 OreochromisOreochromisOreochromis niloticus niloticusEntropy and and17(7): indigenousindigenous 4959–4973. congenericscongenerics doi: https://doi.org/10.3390/e17074959 inin SouthernSouthern Africa:Africa: ShouldShould wewe bebe concerned? concerned? 652 650649649 chards,OreochromisOreochromis sprats, shads, anchoviesniloticusniloticusEntropy 17(7):andand wolf-herrings,indigenousindigenous 4959–4973.Plate congenericscongenerics Part doi:- I https://doi.org/10.3390/e17074959 innichein SouthernSouthern overlap Africa:Africa: between ShouldShould invasive wewe Nile bebe concerned?concerned? tilapia Oreo - 651650650 1: Chirocentridae, ClupeidaeEntropyEntropy and 17(7): 17(7):Pristigasteridae. 49594959––4973.4973. FAO doi: https://doi.org/10.3390/e17074959chromis niloticus and indigenous congenerics in South- 650650 EntropyEntropy 17(7):17(7): 49594959––4973.4973. doi:doi: https://doi.org/10.3390/e17074959https://doi.org/10.3390/e17074959 651650 Fisheries Synopsis 125(7):Entropy 113-114. 17(7): 4959–4973. doi: https://doi.org/10.3390/e17074959ern Africa: Should we be concerned? Entropy 17(7): 652651651651 Plate -I 4959-4973. doi: https://doi.org/10.3390/e17074959 652651651 Plate -I 652652652 PlatePlate--II 652652 PlatePlate--II PLATE I

1. CLUPEIDAE Sardinella longiceps 2. CLUPEIDAE Sardinella fimbriata

1. CLUPEIDAE Sardinella longiceps 2. CLUPEIDAE Sardinella fimbriata 1. CLUPEIDAE Sardinella longiceps 2. CLUPEIDAE Sardinella fimbriata 1. CLUPEIDAE Sardinella longiceps 2. CLUPEIDAE Sardinella fimbriata 1.1. CLUPEIDAE 1.CLUPEIDAE CLUPEIDAE Sardinella SardinellaSardinella longiceps longicepslongiceps 2.2.2. CLUPEIDAE CLUPEIDAECLUPEIDAE Sardinella Sardinella fimbriataw fimbriata 1.1. CLUPEIDAECLUPEIDAE SardinellaSardinella longicepslongiceps 2.2. CLUPEIDAECLUPEIDAE SardinellaSardinella fimbriatafimbriata

3. ENGRAULIDAE Thryssa kammalensoides 4. ENGRAULIDAE Thryssa spinidens 3. ENGRAULIDAE Thryssa kammalensoides 3. 3.ENGRAULIDAE 3.ENGRAULIDAE ENGRAULIDAE Thryssa Thryssa kammalensoideskammalensoides kammalensoides 4. ENGRAULIDAE Thryssa spinidens 3. ENGRAULIDAE Thryssa kammalensoides 4. ENGRAULIDAE ThryssaThryssa spinidens spinidens 3. ENGRAULIDAE Thryssa kammalensoides 4. ENGRAULIDAE Thryssa spinidens 3.3. ENGRAULIDAEENGRAULIDAE ThryssaThryssa kammalensoideskammalensoides 4. ENGRAULIDAE Thryssa spinidens 4.4. ENGRAULIDAEENGRAULIDAE ThryssaThryssa spinidensspinidens

6. TRICHIURIDAE Eupleurogrammus glossodon 5. SCOMBRIDAE5. SCOMBRIDAE Scomberomorus Scomberomorus lineolatus lineolatus 6. TRICHIURIDAE Eupleurogrammus glossodon 5.5. SCOMBRIDAESCOMBRIDAE Scomberomorus Scomberomorus lineolatus lineolatus 6.6. TRICHIURIDAETRICHIURIDAE Eupleurogrammus glossodon glossodon 5. SCOMBRIDAE Scomberomorus lineolatus 6. TRICHIURIDAE Eupleurogrammus glossodon 5.5. SCOMBRIDAE SCOMBRIDAE ScomberomorusScomberomorus lineolatuslineolatus 6.6. TRICHIURIDAETRICHIURIDAE EupleurogrammusEupleurogrammus glossodonglossodon 5.5. SCOMBRIDAESCOMBRIDAE ScomberomorusScomberomorus lineolatuslineolatus 6. TRICHIURIDAE Eupleurogrammus glossodon

7. GOBIIDAE Acentrogobius cyanomos 8. 8.GOBIIDAE8. GOBIIDAE GOBIIDAE Oxyurichthys Oxyurichthys Oxyurichthys microlepis microlepis microlepis 7. GOBIIDAE7.7.7. GOBIIDAEGOBIIDAE GOBIIDAE Acentrogobius Acentrogobius AcentrogobiusAcentrogobius cyanomos cyanomos cyanomos 8. GOBIIDAE OxyurichthysOxyurichthys microlepis microlepis 7. GOBIIDAE Acentrogobius cyanomos 8. GOBIIDAE Oxyurichthys microlepis 7. GOBIIDAE Acentrogobius cyanomos 8.8. GOBIIDAEGOBIIDAE OxyurichthysOxyurichthys microlepismicrolepis 7.7. GOBIIDAEGOBIIDAE AcentrogobiusAcentrogobius cyanomoscyanomos 8. GOBIIDAE Oxyurichthys microlepis

9. SPHYRAENIDAE Sphyraena jello 9. SPHYRAENIDAE Sphyraena jello 9. SPHYRAENIDAE Sphyraena jello 10. SOLEIDAE Solea ovata 10.10. SOLEIDAE SOLEIDAE Solea Solea ovata ovata

11. CYNOGLOSSIDAE Cynoglossus quadrilineatus 12. CYNOGLOSSIDAE Cynoglossus semifasciatus

11. CYNOGLOSSIDAE Cynoglossus quadrilineatus 12. CYNOGLOSSIDAE Cynoglossus semifasciatus

13. CYNOGLOSSIDAE Cynoglossus macrolepidotus 14. TETRAODONTIDAE Lagocephalus guentheri

13. CYNOGLOSSIDAE Cynoglossus macrolepidotus 14. TETRAODONTIDAE Lagocephalus guentheri

15. AMBASSIDAE Parambassis lala 16. GERREIDAE Gerres macracanthus

15. AMBASSIDAE Parambassis lala 16. GERREIDAE Gerres macracanthus

17. SCIAENIDAE Otolithes ruber 18. SCIAENIDAE Pennahia aneus

19. SCIAENIDAE Johnius carouna 20. MULLIDAE Upeneus sulphureus 17. SCIAENIDAE Otolithes ruber 18. SCIAENIDAE Pennahia aneus 653

19. SCIAENIDAE Johnius carouna 20. MULLIDAE Upeneus sulphureus 653

9.9. SPHYRAENIDAESPHYRAENIDAE SphyraenaSphyraena jellojello 9.9. SPHYRAENIDAESPHYRAENIDAE SphyraenaSphyraena jellojello [25] 9.9. SPHYRAENIDAESPHYRAENIDAE SphyraenaSphyraena jellojello 9.9. SPHYRAENIDAESPHYRAENIDAE SphyraenaSphyraena jellojello 10. SOLEIDAE Solea ovata 10.10. SOLEIDAESOLEIDAE SoleaSolea ovataovata 10.10. SOLEIDAESOLEIDAE SoleaSolea ovataovata 10.10. SOLEIDAESOLEIDAE SoleaSolea ovataovata

11.11. CYNOGLOSSIDAECYNOGLOSSIDAE CynoglossusCynoglossus quadrilineatusquadrilineatus 12.12. CYNOGLOSSIDAECYNOGLOSSIDAE CynoglossusCynoglossus semifasciatussemifasciatus 11.11. CYNOGLOSSIDAECYNOGLOSSIDAE CynoglossusCynoglossus quadrilineatusquadrilineatus 12.12. CYNOGLOSSIDAECYNOGLOSSIDAE CynoglossusCynoglossus semifasciatussemifasciatus 11.11.11. CYNOGLOSSIDAE CYNOGLOSSIDAE CYNOGLOSSIDAE CynoglossusCynoglossus quadrilineatus quadrilineatus quadrilineatus 12.12. CYNOGLOSSIDAE CYNOGLOSSIDAE CynoglossusCynoglossus semifasciatus semifasciatus 11.11. CYNOGLOSSIDAECYNOGLOSSIDAE CynoglossusCynoglossus quadrilineatusquadrilineatus 12.12. CYNOGLOSSIDAECYNOGLOSSIDAE CynoglossusCynoglossus semifasciatussemifasciatus

13.13. CYNOGLOSSIDAECYNOGLOSSIDAE CynoglossusCynoglossus macrolepidotusmacrolepidotus 14.14. TETRAODONTIDAETETRAODONTIDAE LagocephalusLagocephalus guentheriguentheri 13.13. CYNOGLOSSIDAECYNOGLOSSIDAE CynoglossusCynoglossus macrolepidotusmacrolepidotus 14.14. TETRAODONTIDAETETRAODONTIDAE LagocephalusLagocephalus guentheriguentheri 13.13.13. CYNOGLOSSIDAE CYNOGLOSSIDAE CYNOGLOSSIDAE CynoglossusCynoglossus macrolepidotus macrolepidotus macrolepidotus 14.14.14. TETRAODONTIDAE TETRAODONTIDAE LagocephalusLagocephalus guentheriguentheri 13.13. CYNOGLOSSIDAECYNOGLOSSIDAE CynoglossusCynoglossus macrolepidotusmacrolepidotus 14.14. TETRAODONTIDAETETRAODONTIDAE LagocephalusLagocephalus guentheriguentheri

15.15. AMBASSIDAEAMBASSIDAE ParambassisParambassis lalalala 16.16. GERREIDAEGERREIDAE GerresGerres macracanthusmacracanthus 15.15.15. AMBASSIDAEAMBASSIDAE AMBASSIDAE ParambassisParambassis lala lalalala 16.16. GERREIDAEGERREIDAE GerresGerres macracanthusmacracanthus 15.15. AMBASSIDAEAMBASSIDAE ParambassisParambassis lalalala 16.16. GERREIDAE GERREIDAE GerresGerres macracanthus macracanthus 15.15. AMBASSIDAEAMBASSIDAE ParambassisParambassis lalalala 16.16. GERREIDAEGERREIDAE GerresGerres macracanthusmacracanthus

17. SCIAENIDAE Otolithes ruber 17.17.17. SCIAENIDAESCIAENIDAE SCIAENIDAE OtolithesOtolithes ruber ruberruber 18.18. SCIAENIDAESCIAENIDAESCIAENIDAE PennahiaPennahia aneusaneus 17.17.17. SCIAENIDAE SCIAENIDAESCIAENIDAE Otolithes OtolithesOtolithes ruber ruberruber 18.18. SCIAENIDAESCIAENIDAE PennahiaPennahia aneusaneus 17.17. SCIAENIDAESCIAENIDAE OtolithesOtolithes ruberruber 18.18. SCIAENIDAE SCIAENIDAE PennahiaPennahia aneus aneus 17. SCIAENIDAE Otolithes ruber 18.18. SCIAENIDAESCIAENIDAE PennahiaPennahia aneusaneus

19.19. SCIAENIDAE SCIAENIDAE JohniusJohnius carouna carouna 20. MULLIDAE Upeneus sulphureus 19.19. SCIAENIDAESCIAENIDAE JohniusJohnius carounacarouna 20.20. MULLIDAEMULLIDAE UpeneusUpeneus sulphureussulphureus 19.19. SCIAENIDAESCIAENIDAE JohniusJohniusJohnius carouna carounacarouna 20.20. MULLIDAEMULLIDAE UpeneusUpeneus sulphureussulphureus 653 19.19. SCIAENIDAESCIAENIDAE JohniusJohnius carounacarouna 20.20. MULLIDAEMULLIDAE UpeneusUpeneus sulphureussulphureus 653653 653653 653653