Of the total annual marine fin fish production of India, ground fishes have accounted for about 25% in recent years

Bensam, P

Menon, N G

CMFRI Digital Repository

ON CONSERVATION OF CERTAIN COMMERCIALLY E GROUNDFISH RESOURCES OF INDIA Abstract '., ')j " of the total annual marine finfish production of India, ground fishes have accounted in recent yoars . Since the commencement of mechanisation in fishing, ground fish nrr.eJlIIC" .. n' ... O I"" a marked incroase. But, intensive trawling operations along shallowcoast:pl fi.h'''9 gl'ou.nds depth zone have also resulted in depletion of certain ground fish resources such en the Catfi.sh, Ghol, Koth, Dora, Wam and Karkara. The indiscriminate exploitation of their juveniles a ' the coastal habitat ~.os also resulted in recruitment· overfishing of the above resources. 0Peratioruof purse-seines in the states of Kerala and Karnataka during the late sevenfies a have led to a massive destruction of spawning and broodi ng populations of Catfis,hes.and the wanton destruction of their eggs and embryos. Since this resource is migratolry, the a1bove has .' affected the replenishing potential of the resource and a decline in its production from. 0 111 along Coast$.. It hOi alSeo rO.$vhedin adwme changes in the speclel diversity of this re.ourclt. Th. draws attention to the need for preventing indiscriminate exploitation of such vulnerable rosov Introduction Finfi shes usually inhabiting the sea bottom are many and varied, such as jewfishes, "A.·rH ..... rays, catfishes, silver bellies, flatfishes, liz\:lrd fishes, flat heads and ~Ioatfishes, with che morpho;l,ogica l Cl nd physiological adQpio'fiol'\s . Of f'he fota l 1,400 specie$ recorded from th environment, more than 500 are from the se'a bottom and less than 200 from regular CQ~ demer$al fisheries, some forming shoals . Their diversity is more in the Continental shelf region slope; also more in the east coast than in the west. Many of them undertake vertical and/or migrations in response to environmental factors such as abundance of food, spawning 'behavi rhythm, upwelling, water currents, drift and the like . A large array of demersal finfishes are vu exploitation by (1 wide spectrum of artisanal and mechanised gears, especially the bottom ones. ' UntO the j·ete fj ftiesJ ttxp loitation of tnese re$ource~ Was not adequ,otely unde·rtakend,ue . efficie~t bottom gears. It was only in the late fifties that mechanised bottom gears such as trawl introdu-ced in India, including mechanisation of crafts. This has not only opened up the p adequate e:xplo i ta tion of ground fi nfh hes b WI a lso extendi ng the arees of fishing beyond ~he th about 20 m depth , During 1961-66, about 5,000 small ar,d medium sized bottom trawlers of 7.5-1 (Overall Length) were in operation. Subsequently, the number has increased, including the on netting, purse-seining and long lining, to about 35,000 as at present. There was also motori troditional crafts, which number about 26,000 at present, Besides, there are about 1,80,000 nnn··mlU "Traditional crafts avai lable. Wit·h the progreu of m&ehcmizotion a,nd the increosin'9 efficiency o'f the craf.ts and gean; of fishing has extend d to deepe; walen, Ihus most of the medium sized veuets venturing ypto depth . Simultaneously, the proportion of production by mechanised vessels has increased trom 1 total in 1969 to B 1 % in 1989" The ·demersal finfish component also has increased steo.dilly 0.19 million tonnes (mtl in 1961 to 0.25 mt in 1970,0.42 mt in 1977,0.45 mt in 1989 and 0 . .55 8 985-9'2, forming about 25% of the total marine fi~h production. Howevel', coinciding with andlor as a : result of these advances, certain demersal finfish groups have undergone depletion. The pr8Senl paper 'nrlllllllnlB these facts and suggests ways and means of conservation and judicious eRploitation of the ... 1 .... '01)18" R'esourc:tb-Among the various demersal Finfish groups, the Whale Shark Rhiniodon Typus Smith (family dae) the world's largest fish is said to be the most vulnerable one. Since itis a rore fish, the rUer reports on it were only of its incidental catches and strandings. A minor harpoon fishery for this _ttrot:lIe fr sh was f'l's t r port din, Veravot Gu i a ra t. Th e fj sh e ry I mo is tly for its Ii var an d Ii n $ halco-mm enc:.d clio! ri"9 the early e i,gn ti 91 th,ere, improved therea'her ,and ,go't astab Ii shed as QI regula r one clu r,i ng M~r-ctdun. period" probably the only one of its kind in th~ world. During 1988· 91, 648 &pe-elmens in thellngth ronge of 5.6·12 m and weighing 3,520 t were caught from the depth zone of 30-45m. Although the Wha;l. Shgr~ not be co,u i d~redas on endang~red Fish" ilt IS ohen treated as a vu Iherable one; and wl d.r use of its ~N~~lln and meat shall increase the-efF'orts for Its capture and may resu lt i nits depletion. This group il abundant in the ·muddy eround, of 20" 70 m dep,th %on_ and mOlt spee''', " mf:Clrc:I ~te both ve'rtically and hori%ont,aj'ly paralle,1 to the coast . Among about 23sptcies unde:r tJ.ree generul joJSlWWilrlLL OlteQS.""i.2l!uana BgtrgcbocopbaJus; about t9J1 are commercially exploited by trawJl, gi!; hoo~,and !lnel, PlJr~'leinel and Q wide variety of traditional, gealh. Theyml grate From no·tth to IO\lth ,aouth • west monloon Qnd vice versa during pod monsoon ; and are abu,"da'nt in Guiarot, aroshtral K,orflotoka, Kerale and norfh east coast, Tac;.hyturus tenuispinjs (Day) 50·60 , em, l,iWaI'IW!l!!!!!. 'valenciennes~ 70·80 em., T. Song (H'aml,!ton) 70·80 em and QstOOQ,rliolul mUitqrjl WDl~geNsJ 30·,40 em are the .m-pon-ant ipedes whic;h have u'lndergone dep.letion. -. h: .. The Cat fishes have a long life span and very low fecundity ranging from 30 to 180 eggs, with the gestating the eggs and embryos in their mouth. Recently, large-scale exploitation of Catfishes by seines along Karnataka has resulted in mass destruction of the brooders. An estimate has revealed In the case ofT. tenu;spinis, within the two months·of September·October every year when it congregates ,coastal waters for breeding, more than 8 million eggs and early juveniles alone, weighing about 13 . are destroyed. As a result of this, the average annual produ~tion has declined from 8,'060 t during 919·86 to only about .4,070 t during 198.4-87. This has also led to a t:onsiderable reduction in the r-il\ldt .... ln .. • · to t,he commercial catches subsequently. Since the resource is migratory and as most of the h,ave lOfil9 life span, the above impact is reflected in other parts of the country also, thus the annual . nh'9 from about 56,000 t during 1979-83 period to a marked extent during 198.4-87 and Q:sto34,110tin 1991~ 1 " . ,Lgctarw, Iq~tqriu, (Sehneidel'), the .ingl~ sp-~elesunder faml !y lacterndae ii, almall "9 to CiI max.lmum of about 40 em and moving ~ nsrnall shoals in ,",hore waters. Although ..... nLlL ....... all along the 'ndian coalt, it has been $upportins notable Fis~erie$ QIQng the south'we,t and ,regions. It has h!ad an Impo.rtant Fishery in ,M.alabo~ a ~,e? duri?9 1949-50. On 01'1 a' llndi~ basis has assumed Jmportancefr.om the late Mtuu COinC iding With the commencement 01 bottom-. production hal gradually increased, reac~ing about .4,550 tIn 1969 and an"aU time pctO,l of 1.985. ThertiQfte" th,.,. hos ,been ,Q staady dedine reaching to 6,68.5t 1"111 198'9 and 6,575 t in 9 '1992: Th.d~lin. h~~ been so mark8d in the s~uth-west coast that in a 'single centr., '" rqll.ll.il production which was 62.4 t in 1970 has declin,d to a meagreO. Hin1979.;. :':' -' ,1 ,'t' • • - ' • '1 ~ HI 'n ! <.; , ; , .. , • (J I-i . . 'J I IJ. ... ~ (4) Tbroadfjns ; This group belonging to the Family Polynemldae has been supporting minorQu .... in the north-west and north-east regions. Among the many species, pol)'nemUs indicul ' and p. 'heptadgctylus (cuvier) 20-25 ~m collectively called "pbgra" are the most important. about 1 .2~ of ,he total fhh landings dud ng 1956-60 but have dedi ned to 0.46ft during 1 - during 1977·85 and to al meagre 0.32~ d~ri.ng 1988-92" In tn.e, b~jni,ng stag,8$ of mec:hQI e. Indietls has hod 0 high abundance in Gujarot, Maharalhtra l West aengal and O,illa. ~t, inc rea'S8 of 'bo ttom trowl i 119 i" the s hal low COQstar waters of Guiarat hosled to Q hecwy ~_~.M Iv .... n il., caU. ,d N Chllno" as well QS indiscriminate hC;u'vesfj n9 of 'peermena "n qCII'a"lcel~ condition', Since these sptelesar. hermophodites, the r'emovol of qdvQRCtG matu~ 1pe<:,IIOIII",o tutridiQn' on th,e .regenefat,lng capacity of the sto(ks, (5) ether resqu rces '; .' ," ,'" t-" i, . Species such cb the "~" Pseudosciaeng djgcgnthus, Weber and De U.~'UJ4i11f'J';y.j "Koth· etolithoides brunneus, Fowler, 90-150cm, "Kgrkgrg" pomadgs)'s hasta (Bloch) Ao-~O Murgensox cj nereus (Forukal) 50-80 cm and Congresox tglgbgnod;es (Bleeker), 150-200 em resources along Gujarat - Maharashtra waters till early sixties. Fishable concentrations. of were reported from this region and they have contributed substantially to the fisheries of th ... Ouring 1957·'62 period, the av'erQge caten rate of psoodolcig,ng djasgothul Wei" A 1 5.5~ of the total catch; and that of Otol;tho;des brunneus was 10.2 kg/hour forming 1.AS Maharashtra region. The production rate of Pomadgs),s h.su.m was 63 kg/hour and It formed total catch, whereas M. Cinereus formed 12 .3% of the total catch and contributed at a rate of 91 effo.rt. A dominant demenol resourcoof the cooltal woten is plgt:yeephglul IDQkuljpjnng Regan_ with a wide range of distribution along most of the shallow muddy bottom habitats. Th .... r~'Jd1J11!H the above species has declined considerably in the coastal waters during the tighti.s. It nu:lMIl .. out that their heavy exploitation from the shallow grounds of Kutch, Dwaraka, PQ;rbonder, V'lnnQU!II: and, 6omb.ay water5dvring the early phase of tne mechanised .rQ might b ,e,pon.ibJ. for th. their production. However, quantitative data of many of these resources are no,' avaUobl. evalua-tion of the status of these population. ' • I • 'I • I ~i:. '" I •• 1 I:'JL r liIJ' n d \:;ri': ,f! IU : ~ r I, Cause~ for Depletion 'I The demersal fin fishes and other benthic biota in the coastal ecosystem have b .. ~ interacting with one another as well as with the abiotic environment, to maintain an eg""ililil. ma,intenance o,f op.imal 'evef of populotion of each speciel is the mOlor f'actor to keep th.sVsltMIllI condition. Any rise or fall of individual component organisms due to anthropogenic .flKts other reason can cause ecological imbalances with disastrous effects on all the components!"-T-t.. and intensive exploitation of the marine fishery resources with the help of advanced tech become significant in recent years. Consequently some of the species have r,ach,td the OI)lltMUI exploitation and some have even become vulnerable or endangere~. , '(.:t,UI~.a.III , £lL; 'jh~~ .. .J TrawIJish,er~,~ '; , r: . . ~ . I With the introduction and establishment of mechani~ed bottom trawling 'in' '. was a sudden 'purt in the harvest of demersal resources. Attracted by the high pn;,gUlOm~n~~ft'I.Rln from the domestic and th~f9reign markets, more and more trawlers hove entered tbe Tur.n,lnn 10 

Conservation of certain commercially exploited groundfish resources of India

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Conservation of certain commercially exploited groundfish resources of India

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