First record of Mola ramsayi from the Sea of Oman, Sultanate of Oman

Marine Biodiversity Records, page 1 of 4. # Marine Biological Association of the United Kingdom, 2012 doi:10.1017/S1755267212000462; Vol. 5; e63; 2012 Published online

First record of Mola ramsayi from the Sea of Oman, Sultanate of Oman laith jawad, juma al-mamry and lubna al-kharusi Marine Science and Fisheries Centre, Ministry of Agriculture and Fisheries, PO Box 427, Postal Code 100, Muscat, Oman

The first record of the southern ocean sunfish Mola ramsayi in Omani waters is reported based on a single 916 mm total length specimen found stranded on the coasts of Sur City 193 km south of the Omani capital Muscat, 22835 ′ 10.22 ′′ N 59830 ′ 18.91 ′′ E. This account also represents the third northernmost record of a south ocean sunfish in the Indian Ocean. Morphometric and meristic data are provided and compared with those of 5 specimens caught off United Arab Emirates, Brazil and India. The southern ocean distribution of M. ramsayi is corrected in this report.

Keywords: Sea of Oman, Molidae, range extension, Oman, unusual record Submitted 9 December 2011; accepted 8 April 2012

INTRODUCTION

Ocean sunfish or molas belong to the family Molidae. These species are epipelagic in nature (Matsuura, 2002). The molid species are characterized in having a distinctive laterally compressed shape and ‘chopped off’ appearance (Fraser-Brunner, 1951; Smith & Heemstra, 1986), using median fins for swimming, lacking caudal bones, ribs, pelvic fins, spines or girdles and have fewer vertebrae than any other fish (Tyler, 1980). The long history of the family Molidae goes back to the earliest descriptions by Linnaeus (1758) and by Koelreuter (1766) (see Parenti, 2003). Since then, 19 genera and 54 species of sunfish have been proposed (Parenti, 2003) and the taxonomy of the family has been relatively unstable. The most comprehensive taxonomic revision of the family is that of Fraser-Brunner (1951) in which he distinguished five species in three genera: R. laevis, Masturus lanceolatus, Masturus oxyuropterus, Mola mola and Mola ramsayi. At the present, there are four recognized species: R. laevis, Masturus lanceolatus, Mola mola and Mola ramsayi. The latter species is infrequently mentioned in taxonomic treatments (Smith & Heemstra, 1986; Nelson, 1994; Parenti, 2003). Morphological and molecular approaches were attempted to study the relationship among currently recognized genera. Santini & Tyler (2002) using morphological characters and Yamanoue et al. (2004) using molecular data found strong support for the conventional hypothesis of a sister taxon relationship between the genera Masturus and Mola, with Ranzania holding the basal position within the family. The known distribution of M. ramsayi is in the southern oceans, south-west Pacific: Australia and New Zealand, southeast Pacific: Chile and south-east Atlantic: South Africa. Al-Ghais (1994) recorded this species from the eastern coasts of the United Arab Emirates at the northern part of the Sea of Oman. That was the first record of this species from the northern hemisphere. Later, Mohan et al. (2006) recorded it from Chennai waters, India and it was the

second appearance for this species in the northern hemisphere. In the present study, we recorded M. ramsayi for the first time from the Omani waters. This is the third record for this species from the northern hemisphere and the second for the Sea of Oman.

RESULTS

systematics MOLIDAE Mola ramsayi (Giglioli, 1883)

material examined OMMSFC 1085, 916 mm total length (TL), 80 kg, 10 September 2011, coasts of City of Sur (N1384000 E4982000), found stranded on the coast (Figure 1). The fish was strange to the fishermen and their colleagues, who wanted to get rid of it, thinking that it was a ‘bad omen’.

description Mola ramsayi differs from M. mola in the following set of characters given by Fraser-Brunner (1951): skin smooth with no denticles and no band of reduced denticles between dorsal and anal fins (Figure 2A) (in M. mola, skin rough with small denticles including a band of somewhat reduced denticles between the bases of the dorsal and anal fins); ossicles close together, much broader than spaces between them (Figure 2B – D) (in M. mola, ossicles widely separated, less broad than spaces between them); clavus supported by about 16 fin rays, of which 12 bear ossicles (Figure 2B) (in M. mola, clavus supported by about 12 fin rays, of which 8 or 9 bear ossicles). Morphometric and meristic details following Matsuura (2002) are given in Table 1.

remarks Corresponding author: L. Jawad Email: [email protected]

Occurrence of sunfishes in the Arabian Gulf and the Sea of Oman are frequent in the past two decades. Ranzania laevis and Mola mola were recorded (Al-Baz et al., 1999; Jawad 1

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Fig. 1. Mola ramsayi, total length 916 mm.

et al., 2011) from the Arabian Gulf, while only R. laevis was recorded from the Sea of Oman (Jawad et al., 2010). Based on the record given in the present study and the other two records from the northern hemisphere (Al-Ghais, 1994; Mohan et al., 2006), the species is more wide ranging than suspected before (Parenti, 2003). Also, this is an oceanic fish and the restricted distribution found in the literature is probably due to insufficient data. The vernacular name seems to be inappropriate but we decided not to suggest an alternative name for a species well known as such in the southern hemisphere.

As far as the authors are aware, few studies have provided morphological measurements for the recorded sunfish specimens collected from the seas of the world (Al-Ghais, 1994; Brito, 2003; Mohan et al., 2006). The full morphological data were compared with that of the present study (Table 1). The maximum size reached by this species is 1215 mm TL (Al-Ghais, 1994). The size of our specimen falls well above the half size given by Al-Ghais (1994). The remaining body proportions agree with those given by other authors (Table 1). The specimens became stranded for the following possible reasons: (1) net entanglement followed by stress; (2) susceptibility to shark attacks; (3) locomotion difficulty stemming from injuries and exhaustion; and (4) body striking the reefs that form a barrier before arriving at the site where the specimen was found. There are several fishing net marks revealing that the fish must have been entangled in a fishing net and suffered stress and trauma. Such a state enabled attacks from predators and probably from parasites. Accidental entanglement in fishing gear is one of the main threats to M. ramsayi populations in particular (Arau´jo et al., 2010) and mola populations in general, as species from the family are often reported as by-catch in lone-line fisheries (Joung et al., 2005) and drift nets (Akiol et al., 2005). During the external analysis of the specimen, few recent and old shark bites of different shapes and origins were found. The sides of the body showed more bites than any other body regions. This may likely be due to the fact that these areas are the largest and most easily accessed in this type of attack (Souto et al., 2007). Under such a bad morphological state, the specimen must have remained adrift and, upon approaching the coast, suffered a number of scratches from the reefs near by. There are several possible explanations for the presence of this fish in the coastal waters of the Sea of Oman (e.g. ballast water of ships playing between Europe and the Persian Gulf). Predominantly marine, M. ramsayi is a species with different

Fig. 2. Mola ramsayi: (A) smooth skin; (B) state of ossicles at clavus; (C) clear area at dorsal fins; (D) cear area at anal fins.

first record of mola ramsayi from the sea of oman

Table 1. Morphometric and meristic characteristics of Mola ramsayi in the Sea of Oman compared with specimens from the literature (NA, not available). Morphometric characters (mm) and ratio

Present study

Al-Ghais, 1994

Brito, 2003

Mohan et al., 2006

Total length (TL) Eye diameter % in TL Preorbital length % in TL Preoperculum length % in TL Predorsal fin length % in TL Hight of dorsal fin % in TL Distance between base of dorsal and anal fin Prepectoral fin length % in TL Hight of anal fin % in TL Preanal fin length % in TL Preanus length % in TL Maximum body depth % in TL Meristic characters Dorsal soft rays Anal soft rays Pectoral fin rays

916 50 5.5 135 14.7 277 30.2 540 58.9 470 51.3 1426 310 33.8 440 48 520 56.8 493 53.8 640 69.9

1215 NA NA NA NA NA NA NA NA 610 50.2 NA NA NA 585 48.1 NA NA NA NA NA NA

650–940 45–61 6.5–6.9 90–128 13.6–13.9 NA NA 423–623 65.1–67 310–505 47.7–53.5 NA 245–338 35.8–37.7 300–500 46.2–53 430–625 66.2–69.4 NA NA NA NA

835 42 5 120 14.4 250 29.9 545 65.3 435 52.1 1260 272 32.6 400 47.9 NA NA 555 66.5 600 71.9

19 17 12

NA NA NA

17 17 12

NA NA NA

ecological preferences, for example, it has a larval pelagic existence in coastal waters (Fraser-Brunner, 1951). Changes in environmental factors might relate to the presence of this species in the waters of the Sea of Oman. Warmer water masses might cause the southern ocean sunfish to proceed further north of its native distribution. A sudden southern warming process of the sea surface in the Oman Sea area was evident during the period July–August 2011 where warm water masses were recorded entering through the Strait of Hurmoz (Al-Ahaqsi, personal communication). Different species of molas showed a relation between their presence and the sudden rise in sea surface water temperature. Castro & Ramos (2002) and Jawad et al. (2010) related the presence of R. laevis off Gran Canaria (Canary Islands) and the Sea of Oman respectively to the sudden warming process of the sea surface in the central Atlantic and the Sea of Oman. Since only one specimen was collected and since no further individuals were obtained, it is premature at this stage to consider this species among the fish fauna of Oman. It should only be considered as such, if a breeding population of this species is maintained in the area.

ACKNOWLEDGEMENTS

We thank the Ministry of Agriculture and Fisheries Wealth, the directorate of Agriculture and Fisheries Development Fund and the Marine Science and Fisheries Centre for giving us the opportunity to work on fish samples from the Sultanate of Oman and for providing the appropriate financial support. We thank Professor Dr Paolo Parenti of the Department of Environmental Sciences, University of Milano Bicocca for confirming the species identification and for his valuable advice and

suggestions in reading the manuscript. We thank Dr Ofer Gon of the South African Institute of Aquatic Biodiversity for his valuable advice and suggestions.

REFERENCES Akiol O., Erdem M., Unal V. and Ceyham T. (2005) Investigations on drift-net fishery for swordfish (Xiphias gladius L.) in the Aegean Sea. Turkish Journal of Veterinary and Animal Sciences 29, 1225–1231. Al-Baz A.F., Bishop J.M. and Hamza B. (1999) First Arabian Gulf records of Molidae from Kuwait. Kuwait Journal for Science and Technology 26, 315 –320. Al-Ghais S.M. (1994) A first record of Mola ramsayi (Osteichthyes: Molidae) for the United Arab Emirates. Tribulus 4, 22. Arau´jo M.E., Silva-Falca˜o E.C., Falca˜o P.D., Marques V.M. and Joca I.R. (2010) Stranding of Masturus lanceolatus (Actinopterygii: Molidae) in the estuary of the Una River, Pernambuco, Brazil: natural and anthropogenic causes. Marine Biodiversity Records 3, 1–5. DOI: http://dx.doi.org/10.1017/S1755267210000588. Brito J.L. (2003) Nuevos registros de Balistes polylepis (Balistidae), Sphoeroides lobatus (Tetraodontidae), Mola mola y M. ramsayi (Molidae) en San Antonio, Chile (Pisces, Tetraodontiformes). Investigaciones Marina, Valparaı´so 31, 77–83. Castro J.J. and Ramos A.G. (2002) The occurrence of Ranzania laevis off the Island of Gran Canaria, the Canary Islands, related to sea warming. Journal of Fish Biology 60, 271–273. Fraser-Brunner A. (1951) The ocean sunfishes (family Molidae). Bulletin of the British Museum (Natural History) Zoology 1, 87–121. Jawad L., Al-Mamry J. and Kharusi L.H. (2010) The slender sunfish, Ranzania laevis (Actinopterygiformes: Molidae), in the coastal waters of the Oman Sea. Acta Ichthyologica et Piscatoria 40, 105–108.

3

4

laith jawad et al.

Jawad L.A., Hussein S.A. and Bulbil F. (2011) Ranzania laevis (Pennant, 1776) (Tetraodontiformes, Molidae): a rare fish in marine waters of Iraq. Journal of Applied Ichthyology 27, 1116–1118.

Santini F. and Tyler J.C. (2002) Phylogeny of the ocean sunfishes (Molidae, Tetraodontiformes), a highly derived group of teleost fishes. Italian Journal of Zoology 69, 37–43.

Joung S.J., Liu K.M., Liao Y.Y. and Hsu H.H. (2005) Observed by-catch of Taiwanese tuna longline fishery in the South Atlantic Ocean. Journal of the Fisheries Society of Taiwan 32, 69–77.

Smith M.M. and Heemstra P.C. (eds) (1986) Smith’s Sea fishes. Johannesburg: Macmillan South Africa. [Reprinted with 1995 additions and corrections by Straik, Cape Town, South Africa, 2003.]

Koelreuter I.T. (1766) Piscium rariorum e mus. petrop. exceptorum descriptiones continuatae. Novi Commentarii Academiae Scientiarum Imperialis Petropolitanae 10, 329–351, Pl. 8.

Souto L.R.A., Oliveira J.G.A., Nunes J.A.C.C., Maia-Nogueira R. and Sampaio C.L.S. (2007) Analise das mordidas de tubara˜o-charuto, Isistius spp. (Squaliformes: Dalatiidae) em ceta´ceos (Mammalia: Cetacea) no litoral da Bahia, nordeste do Brasil. Biotemas 20, 19–25.

Linnaeus C. (1758) Systema Naturae, ed. X. (Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis). Tomus I. Holmiae [Stockholm]: Editio decima, reformata, i –ii + 1–824 pp. Matsuura K. (2002) Molidae. Molas (ocean sunfishes, headfishes). In Carpenter K.E. (ed.) FAO species identification guide for fishery purposes. The living marine resources of the western central Atlantic. Bony fishes, part 2 (Opistognathidae to Molidae), sea turtles and marine mammals, Volume 3. Tokyo: FAO, pp. 2014–2015. Mohan S., Selvanidhi S., Srinivasan G. and Poovannan P. (2006) Mola ramsayi (southern sunfish): a new record from Indian waters. Marine Fisheries Information Service, Technical and Extension Series 189, 23–24. Nelson J.S. (1994) Fishes of the world. 3rd edition. New York: John Wiley & Sons, 600 pp. Parenti P. (2003) Family Molidae Bonaparte 1832—molas or ocean sunfishes. Annotated Checklists of Fishes 18, 1 –9.

Tyler J. (1980) Osteology, phylogeny, and higher classification of the fishes of the order Plectognathi (Tetraodontiformes). NOAA Technical Report NMFS 434, 1 –422. and Yamanoue Y., Miya M., Matsuura K., Katoh M., Sakai H. and Nishida M. (2004) Mitochondrial genome and phylogeny of the ocean sunfishes (Tetraodontiformes: Molidae). Ichthyological Research 51, 269–273.

Correspondence should be addressed to: L. Jawad Marine Science and Fisheries Centre Ministry of Agriculture and Fisheries PO Box 427, Postal Code 100, Muscat, Oman email: [email protected]