Aristaeopsis edwardsiana (Johnson,1867) is a deepsea shrimp of the continental slope that has not yet been reported in the

targeted deepsea crustacean fishery along the Indian coast. An exploratory survey on-board FORV Sagar Sampada in the

Arabian sea at a depth of 950 m off Trivandrum (lat. 8 0 28’ N and long. 76 014’ E) yielded a catch of A. edwardsiana at a

high catch per unit effort (CPUE) of 14 kg h-1. The biological aspects of this less known deepsea shrimp species such as

length frequency distribution, morphometric relations, sex ratio and the additional sexual dimorphism manifested in the

antennal scale of males are reported

Akhilesh, K V

Ganga, U

Manjebrayakath, Hashim

Rajool Shanis, C P

CMFRI Digital Repository

29An account on the deepsea shrimp Aristaeopsis edwardsiana (Johnson, 1867)from the Indian EEZU. GANGA,  C. P. RAJOOL SHANIS, HASHIM MANJEBRAYAKATH ANDK. V. AKHILESHCentral Marine Fisheries Research Institute, P. B. No.1603, Kochi - 682 018, Kerala, Indiae-mail: ganga@cmfri.org.inABSTRACTAristaeopsis edwardsiana (Johnson,1867) is a deepsea shrimp of the continental slope that has not yet been reported in thetargeted deepsea crustacean fishery along the Indian coast. An exploratory survey on-board FORV Sagar Sampada in theArabian sea at a depth of 950 m off Trivandrum (lat. 8 0 28’ N and long. 76 014’ E) yielded a catch of  A. edwardsiana at ahigh catch per unit effort (CPUE) of 14 kg h-1. The biological aspects of this less known deepsea shrimp species such aslength frequency distribution, morphometric relations, sex ratio and the additional sexual dimorphism manifested in theantennal scale of  males are reported.Keywords: Aristaeopsis edwardsiana, Aristeidae, Deepsea shrimp, Indian EEZIntroductionThe aristeid shrimp Aristaeopsis edwardsiana(Johnson, 1867) popularly known as the scarlet shrimp(formerly Plesiopenaeus edwardsianus) was reported in theIndian EEZ by Alcock (1910) and its occurrence offTrivandrum (lat. 8 0 28’ N and long. 76 014’ E) at depths> 800 m,  based on four specimens caught was confirmedby Suseelan and George  (1990). In the present study, duringan exploratory survey in the same region (lat. 8 0 24’ N andlong. 76 0 07’ E) the CPUE of A. edwardsiana was14 kg h-1 which was quite high in comparison to reports ofcatch rates of 2 kg h-1 off the Portugal continental slope(Figueiredo et al., 2001) and 3.7 – 10 kg h -1 reported offBrazilian coast where a sustainable targeted deep-sea fishingfor aristaeid shrimps is prevalent (Pezzuto et al., 2006).A. edwardsiana  is characterised  by features like theabsence of exopods on the first to fifth pereopods, first andsecond pereopod without distal meral spine and the absenceof hepatic spine (Farfante and Kensley, 1997). Molecularphylogenetic analysis has established that Aristaeopsis isdistinct from the Plesiopenaeus but closely related toAristaeomorpha, another important genus in the familyaristeidae (Ma et al., 2009). Considering the fact thatdeepsea shrimps in general have biological traits such asslow growth, late maturity and low fecundity making themespecially vulnerable to over-exploitation as compared tocoastal shrimp species (Nandakumar et al., 2001), detailedstudies on the biology of the species are necessary beforeits exploitation by commercial vessels are allowed. TheIndian J. Fish., 59(1) : 29-31, 2012present study therefore explores a sample of A. edwardsianacaught during the exploratory deep-water fish survey forbiological details.Materials and methodsSamples were collected during an exploratorydeepwater research survey (FORV Sagar Sampada cruiseNo.281) using High Speed Demersal Trawl - CrustaceanVersion (HSDT CV) net at a depth of 950 m. The speciesappeared in a catch mix consisting of finfish, crustaceanand chondrichthyans and was identified based ondistinguishing characters as given by Farfante and Kensley(1997) and Poore and Ahyong (2004). Standardmorphometric measurements of the sample included totallength (TL) as measured (in mm) from tip of rostrum to tipof telson; and carapace length (CL) from posterior marginof the orbit to posterior dorsal margin of carapace (Dallet al., 1990). The specimens (n = 224) were differentiatedamong sexes using the characters of presence of petasma(males) or thelycum (females) and the relationship betweenTL and CL was derived using the linear relationship,Y= a + bX for males and females separately. Besides this,sexual dimorphism manifested as appearance of antennalscales in males in certain aristeid shrimps is described forthis species in Indian waters for the first time.ResultsLength Frequency distribution and sex ratio The total length (TL) varied from 168 to 295 mm andcarapace length (CL) from 51 - 95 mm. The minimum and30U. Ganga et al.maximum TL were 168 and 246 mm (males) and 190 and295 mm (females) respectively with mean TL of 195 and254 mm for males and females respectively (Fig. 1).Significant correlation between CL and TL was observedas TL = 0.1284 + 3.39 CL (R2 =0.933) in males andTL = 6.123 + 2.45 CL  (R2 = 0.946) in females (Fig. 2).Among a total 224 specimens of A. edwardsianastudied, 163 were females and 61 were males indicating amale: female sex ratio of 1:2.7 which was significantlydifferent (l2 = 23.22, p < 0.001).elongate in females and juvenile males, reaching beyondapex of scaphocerite and somewhat shorter in adult males.DiscussionThe present study conducted in October 2010 whichcovered transects between  80- 210 N latitudes in the ArabianSea observed occurrence of A. edwardsiana  only at 80 Nlatitude at 900 m depth, indicating a very geographicallyand bathymetrically limited stock. Exploratory surveys inBrazil and French Guiana also report that the species ishighly concentrated in the vicinity of the 800 m isobath(Gueguen, 1998; Pezzuto et al., 2006). While Suseelan andGeorge (1990) reported  four female specimens in lengthrange of 20.7 - 24.5 cm TL, a relatively high CPUE ofabout 14 kg h1 was observed in the present study whichyielded information on length frequency distribution, sexratio and morphometric relations. However, the presentstudy was also limited by a pre-defined samplingprogramme wherein trawling operations at various depthsin the same ground were not possible. Spatial (depth-wise,canyons, open slope) and temporal segregation of sizes andsexes have been widely reported in aristeid shrimps (Sardaet al., 1997; Guegen, 1998; Figueiredo et al., 2001 andPezzuto et al., 2006) probably as a result of factors relatedto seasonal reproductive pattern (Sarda et al., 2003). Thishas important implications regarding the capacity of thespecies to withstand high or uncontrolled fishing pressureand therefore more detailed surveys are required in thefishing ground identified.Among aristeid shrimp, this particular genus isdistinguished by an additional sexually dimorphic characterin the antennal scale (Farfante and Kensley, 1997; Pooreand Ahyong, 2004 ) which is described in the present study.Females were found to dominate the catch and similarobservations of females dominating the landings of aristeidshrimps irrespective of season and depth have been reported(Guegen, 1998). A thorough understanding of thereproductive potential of the species  can be achieved onlyby dedicated surveys of the fishing ground identified atvarious depths to arrive at reasonable estimates ofpopulation structure including depth-wise abundance,length distribution, sex ratio and maturity stages.AcknowledgmentsWe thank Dr. G. Syda Rao, Director, CMFRI forproviding all facilities and encouragement during the study.We  also thank the Director, CMLRE and Ministry of EarthSciences for funding support. Sincere thanks to the FishingMaster Mr. Xavier Thomas Paul for his help during cruiseno. 281 FORV Sagar Sampada and  all cruise participantsfor their co-operation.Fig. 1. Length frequency distribution of A. edwardsianaFig. 2. Relationship between carapace length (CL) and totallength (TL) for male and female A. edwardsianaFig. 3. Shape of scaphocerite in male (A) and female(B) A. edwardsianaSexual dimorphismThe species exhibits an additional sexually dimorphiccharacteristic in that the scaphocerite (antennal scale) hasan elongate acuminate tip in the males as compared tofemales (Fig. 3). The rostrum was found to be moderately31The deepsea shrimp Aristaeopsis edwardsianaReferencesAlcock, A. 1901. A descriptive catalogue of Indian deep-seaCrustacea, Decapoda, Macrura and Anomala in the IndianMuseum. Indian Museum, Calcutta, 286 pp.Dall, W., Hill, B. J., Rothlisberg, P. C. and Sharples, D. J.  1990.The biology of the Penaeidae. In: Blaxter, J. H. S andSouthward, A. J. (Eds.) Advances in Marine Biology.Academic Press, 27: 489 pp.Farfante, P. I. and Kensley, B. 1997. Penaeoid and sergestoidshrimps and prawns of the world. Keys and diagnoses forthe families and genera. Memoires du Museum Nationald’Histoire Naturelle, 233 pp.Figueireodo, M. J., Ivone, F. and Pedro, B. M. 2001. Deep waterpenaeid shrimps (Crustacea: Decapoda) from off theportugese continental slope: an alternative future resource.Fish. Res., 51: 321-326.Guegen, F. 1998. Biology of the deep-water shrimp Plesiopenaeusedwardsianus in French Guiana. Animal Biology,C. R. Academic Science, Paris, 321: 757 – 770.Ma, K. Y., Chan.T.  Y. and Chu, K. H. 2009. Phylogeny of penaeoidshrimps (Decapoda: Penaeoidea) inferred from nuclearprotein-coding genes. Mol. Phylogenet. Evol., 53: 45–55.Nandakumar, G., Rajan, K. N. and Chellappan, K. 2001. Is thedeep sea prawn fishery of Kerala sustainable? Mar. Fish.Infor. Serv., T  & E Ser., 170 : 5-9.Pezzuto, P. R., Perez, J. A. A. and Wahrlich, R. 2006. Deepseashrimp (Decapoda:Aristeidae): New targets of thedeep-water trawling fishery in Brazil. Braz.  J. Oceanogr.,54(2/3): 123-134.Poore G. C. B. and Ahyong, S. T. 2004. Marine decapod Crustaceaof southern Australia: a guide to identification, CSIRO,574 pp.Suseelan, C. and  George, K. C. 1990 .On the scarlet shrimpPlesiopenaeus edwardsianus (Johnson) caught from thecontinental slope off  Trivandrum, south-west coast of India-An indication of a potential deep-sea prawn resource.Proceedings of the first workshop on scientific  results ofFORV Sagar Sampada, 5-7 June, 1989, Central MarineFisheries Research Institute, Cochin, p. 371-374.Sarda, F., Maynou, F. and Tallo, L. 1997. Seasonal and spatialmobility patterns of rose shrimp Aristeus antennatus in thewestern Mediterranean: results of a long-term study.Mar. Ecol. Prog. Ser.,159: 133-141.Sarda, F., Company, J. B. and Castellon, A. 2003. Intraspecificaggregation structure of a shoal of western Mediterranean(Catalan coast) deep-sea shrimp, Aristeus antennatus(Risso, 1816) during the reproductive period. J. ShellfishRes. 22(2): 569 -579.Date of Receipt : 01.08.2011Date of Acceptance : 17.03.2012

Account on the deepsea shrimp Aristaeopsis edwardsiana (Johnson, 1867) from the Indian EEZ

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Account on the deepsea shrimp Aristaeopsis edwardsiana (Johnson, 1867) from the Indian EEZ

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