A visitor to the Fisheries Laboratory Lowestoft. U. K. cannot fail to be impressed by the significant strides made

by the Institution in fisheries research of particular interest are some of the tools of research either developed or

adopted therefor gear research, fish detection, and estimation of plankton. They are the electronic sector scanning

Sonar, the Transponding Acoustic Fish Tag and the Multi-purpose Hiah-speed Plankton Sampler

Kuthalingam, M D K

CMFRI Digital Repository

Modern Trends in Fisheries Technology in the United Kingdom D r. M. D. K. Kuthal ingam Celltral Marin e Fisheries Research i llsrillllc, Sub - slatioli. Vi: hilljal11. A visitor to the Fisheries Laboratory Lowestoft. U. K. cannot fail to be im-p ress ed by the significant stride s made by the Institution in fisheries research . Of p a rticullr interest are some of the tools of research. e ither developed or a dopted the r e fo r gea r research . fish d etection, and estimation of plankton. They are the Electron ic Sector Scanning Sonar. the Transpon di ng Acoustic Fish Tag and the Multi-purpose Hiah-spe ed Plankton Sampler. At a time when Fish-eries Scie n tists and Administrators in India are unanimous in their efforts in the search for fresh concep ts in basic r esearch in Aquatic Biology and in Fish-eries Technology . it would b e hard Iv necessary to mention that i:1troduction of these tools in India would ensure efficiency and economy in human effort and give a fiilli p to our research in Fisher ies Technology. The advantages that would accrue from these efforts would , very like ly, more tha n offset th e very high initial expenditure involved in the procureme nt of these e qui p ments. E lectronic Sector Scanning Sonar (Fig . 1) FT- - " 1!'"' ' .. The installation of a comple x Elec-tronic Scanning Sonar known as the A . R. L. (Ad miralty Research Laboratory ) Scanner in a fishery research vessel, it s F ig. I. Electronic Sector Scannill g Sonar filled o n R. V. Chone of tIle Fisheries Lab oratury . Lo\\cstoft. May, 1974 II mechanical performance, diagrammatic des.:ription, mode of operation and its uses are dealt with in detail by Mitson and Cook (1 971). Applications of this instrument include fish detection and fish behaviour studies, observation of trawls b oth m mid water and on the sea bed. detection and classification of wrecks and studies on sand waves and othe r sea bed features including detailed survey of grave l extractio n. Detection ranges in excess of 365 m have been achIeved for particular targets, but the normal ranges in general are 320 m for a small wreck, 230 m for a small fish shoal and 180 m lor a single large fish . The lacility with which trawls in ooeratlon Inmldwaterand over a bottom could be observed, with their headline easuy descernible and delineation of consIderable streaming from the otter boards, are special advantages with thIs instrument tor the practical fisher-man who can quickly determine by direct observation of fish abundance areas in which to trawl (Fig . 2). He would first check that the region is clear of rocks , wrecks and other hazards to h is gear. During tra wling, the depth of shoals canbe monitored using elevation scanning, the net height adjus ted, and finall y direct observation of the catch can be made to indicate a suitable time to haul. By using elevation scanning across tra wls, section can be taken along the whole olthe net and the position of th e fish in water co lumn relative to the sea b ed can be determined. It is also possible to measure the vertical extent and d ist ribution of fish shoals. Fish be-ha viour wHh reference to the a ooroach-ing net could also be studied w-ith this sonar. This instrument could be fitted in a ship as small as 45 m length. Deve-lopment of this equipment is complete and its applications are increasing. It appears to be a most important addition to the equipment available for fisheries research in the World. The estimated cost of one u nit of this instrument is about Rs. 20 lakhs. 12 Fig. J. Bott om tra\\ I being to\\ed vvt:r a bUl -tom of sandas s:a nned by the Sector Scanning Sonar. Transponding Acoustic Fish Tag The Transponding Acoustic Fish Tag conS Ists oi a receIver and tra nsm itter used in a transpondmg mode. The sIze of tl:te unit IS 5 cm long by I cm d iameter and it weighs 4.0 g in sea water of sali-n l1Y 350 0 " Ad e talled descriotlon of the design, cons truction and assembly, per-formanCe and trials is given by Musen and Store to n- W est (1971) . When the transponding principle IS used, the puise transmitted from the ship 's s onar is received by the tag and used to trigger its transmitter, th us sending a re turn pulse to the ship. This gives an accurate range measurement between Seafood Export ]ollrnll the ship and the fish. The other mea-surements needed are bearing and depth; and these could be obtained with a high degree of accuracy whe n the ship is fitted with an electronic sector scanning sonar. It has a unique facility wher<3by either azimuth or elevation scanning may be selected at will . th e challge over from one to the other b eing accomplished in 3 seconds. Thus the position of a target in the water column may be determine d r elative to the ship, with in the accu racy of the recei vi ng beam. which has an angular resolution of 0.33' in the scanning plane. This beam in this plan e s~ans a secto r of 3G (Fig. 3) Fig. 3. Diagrammatic representation 0f the operation of ARL Scanner. used in conj unction with a tranponding acous-tic fish tag. On the right is a photograph of the actual scanne r display showing the fish tag signal againsl a background of sa ndwaves. (Figure from the report of the Director Marine Fisherv Re. search Fisheries. Laborat ory Lowestoft ). Although single fish can be de tected and followed by sonar equipment with-out the use of acoustic tags in div iduals cannot be identified. The transponding acoustic tag therefore assists in the May, 1974 study of fish behaviour , m igration , re-action to fishing g ear and movements relat ive to bottom features . Each tag is es timated to cost about Rs. 150.GO B3sides the transpor:d ing acoustic fish tag, other conventional tags are also employed in the United Kingdom (Fig. 4). Tagging and s ubseque nt re-Fig. 4. Conventional fi sh lags. covery of marke d spE:cimens of mar ine fish could reveal directly the degree of intermixture of the fish from dtfferent reg ions of the sea. It also provides information on the migratory behaviour of popula tien , age , g row th and mo r talilY. Among the different lyres of tags used 13 in;;. K" the 'Flag Tag' and 'Bolster Ta gs ' used for herring and macke rel are very s imple and easy to operate on board the vessel. Also th e time co nsumed for tagging is very little and the tags are less expensiee . The above two tags could easily b e tried in Ind ia on th e oil sardine and on the Indian mackerel. Other specia l ty pe of tags , the ' Dart Tags ' meant for larger fishes like tunas (FH-69) and for smaller fishes (FT - 1) as we ll, man ufactured in the Uni te d Sta tes of Ame r ica are also on the ma rket. Cost per 1000 of the latt er two varieti e s wi th-out legend and numbering is about S 220.00 and 582 .50 respectively. The modified gu n (Fig . 5) used for implant-Fig . 5. l\'lark IT. FD-67 la gging gun. ing the tag o n fish have prove d to be far more e ffici ent in tagg ing ve ry small fish as we ll as large fish . Instructions fo r oDe ration of the aun , it s care and taggi~g procedure are p ro vided by the ma n uiactu r ing company* at the time of supply. MulE-purpose High-speed Plankton Sampler (Fig. 6) The Multi-purpose High-speed Plank-ton Sampler has bee n deve loped at the Fisheries Laborator y . Lo westoit. Its design , operation and working charac-teristics have been fully described by • Floy Tag and Manufacturing, fnc. 4616 Union Bay PL N.E. Seattle , Washington 98105. 1-1 Be ve rton and Tungate (1 967) . Th is is more effic ient than a standard plankton ne t for catching the larger and more mobil e plankters , particularly fish larva e. This device wou ld sample si-multaneous ly and in th e same way th e Fig. 6 . High- speed Plank ton Sampler in action abundance no t o n ly of fish eggs and larvae, but a lso that o f their p lanktonic comDeti tors and predators , and in par-ticula r thei r fo od organisms . Thus the mUl ti-p urpose h igh-spe ed pla nk ton sam-ple r ha s become a useful tool mainly in the s tudies of the fish eggs and larvae. The sample r is normall y fished to within I fathom of the sea bottom fr om a vessel stzarr:j r.;- at :: k r: ct s. It is shot Seafood Export }o:lrn.l and hauled at a constant warp speed, and the depth to which it fishes is con-trolled by adjusting the length of the towing cable . This type of haul samples each interval of depth equivalently , but the samples obtained gIve no informa-tion about depths at which the organisms are most a!:>undant. In order to collect uncontaminatEd sample s from selected depths for studying the d~p:h dis trib u-tion of pelaaic fish larvae the LO'1(9Stoft mUlti-purpc-se sampler has been futed WIth net-changing mechanism , the detaIls of which have b"en desc r ibed by Huding et al (l 97 1) . Here the de-SIred net is released to the fishing position , in sequence as the sampler is hauled from one depth interval to the next. In pract ice , ho wever , thlS sam-pler has normally been fished from the deepest level to the surface . changing the nets at se lected levels and samphng four layers of water in succession . Dia-gram:itlc representation of the paper traces for tYPICal hauls are shown inFlg.7. Fig . 7. Diagra m ()f diving profile" Ini tial dive 0'-0" , 0"-1 calibration haul with-out ne ls: numbers I to 4 indicate pusition s at which nets are changed. A. Venical oblique haul s within sc:lected levels. B. Hori zontal hauls at selected levels . (Figure from Hard-ing et al., 1971 ). May. 197-1 The multi-purpose plankton sampler with the net-changing machani,m would therefore sample not only the general abundance but also the vertical distri-bution of the plankters. Calculations of numbers of particular planktonic items per cubic meter and numbers under meter squared could be done from the basic information obtained along with the sampler resulting in the estimation of the volume of water filte red. Since variability of recru itment to the fished stock is most lIkely to be determined at a very ear ly stage in the ltfe h istory, probably dur ing the egg and larval phase, studies of this na tur e are of immediate importance to the fisheries in general. One unit of the sampler is estimated to cost about Rs. 25 thousand. An ear lier design of th e Scanning Sonar installed on P A.S. Gossamer in 1964 was used in an extensive joint trial with the Ministry of Agriculture, FIshe-ries and Food, Fisheries Laborato ry , Lowestoft, during which observations on fish de tec tion and direct observations of shoa l behaviour and observations on mid water trawls were carried. The res ult s have been published by Voglis and Cook (1966), Cushing and Jones (1966) and Cook (1967) . After subseq uent minor modifications to the Sonar itself, the equipment , now known as the A.R.L. Scanning Sonar was fitted in R.V. CLIONE of the Lowestoft Fisheries Laboratory in 1969 in order to carry out work in fisheries research. Since then d etermination of the height of the indlvid1J·a l fish to, for example, the sea bed. and a measure of the vertica l extent and distribution of fish shoals has become possible (Mitson & Ccck. 1971) . By closely followirg the ,hoals of mackerel and other fish, their escape reaction to the approaching fishing gear 15 has also be e n observed with the help of the Sona r (Mitson & Cook, 1971 ). Since then , accord ing to the Report of the Director of Fisheries Re search fo r 1969-71 this e q ui pme nt has bee n used for observi ng fishing gear .. ·jjsh shoals and fe a tures on the sea bottom . Mid-water herring tra wls and bottom traw ls of the type use d by most Br itish deep-sea tra wIers have a lso been observe d in operation. In 1970 and 1971 the fishin g shapes and d imensions of a Gran ton bottom traw ls , a sing le b 03t pelagic tra wl and purs e seines were recorded by use of the ARL Scanner. By manoeuv-ring CLIONE clase b ehind the towi n g tra wle r , trawls were see n fr om above, from behind and fr om the side at ranges u p to 300 m, The details of each tr awl were c learly discernible , e . g. towing warps , otter-boards, bridle s . dan lenos, net and cod -end . The tr anspond ing acoustic tags have b e en tried on plaice and cod fo r tracking exercises concrned wi th their mig ratio n studie s and the de tails are published by Mitson & Store ton-west (197 I) . More rece ntly, according to the report of the Di rec tor of Fisheries Resear ch (1969-71) the tags have also been used for studies of be-haviour of these fishes in re latio n to tr awls . According to Report of the Director me ntiong d earlier the Lowestoft multi· purpose h igh-speed plank ton sampler is regularly e mployed in the offshore s urveys on the known spawning grounds in the English Channel and Southern and Central North Sea to de termine changes in the abundance and dis tributio n of plaice egg s and 16 la rvae, an d of their competitors and pre dators in the plankton community. Of the fo regoing three kinds of equipments , the fi rst two complement each othe r and provide infor mation to the practica l fishermen about th e quantity and kin d of fi sh he can g e t at the moment of fishing , and the third one will e nable the fi shery scientist to advise fishermen on the amo unt of catch of any p artic ular grou p of fi sh that could reasonably be expe cte d under normal cir cumstances in the near future, when it makes its d ebut in the fishery. I than k the F.A.O. author ities, Dr. S. Z. Q uas im , Di rector , Cent ral Mari ne Fisherie s Research Ins titute and Dr. H. A. Cole, Di rector of Fishery Resear ch, Fishery Laboratory, Low e s tofi who have been responsible fo r arranging my F.A .O. fello wship training. I al so thank the Heads of Division of Biology Section and of the G ea r Research and Fish Dete ction Section of the Fishe ry Labora-tory, Lowestoft for th e photogra p hs in this article . My specia l thanks are due to Dr. D. Hardi ng and Mr. J. H. Nichols for the many courtesies extende d to me d uring the tr aining period in the same Laboratory. I also express my thanks to Mr. G. Luther, my colleag ue in th e sub-station for all the help rendered during the prepara tion of this account . REFERE NCE S Beverlon. R. J. S. and D. S. Tungate 1967. A l'vlulli-purpose plankton sampler. J. Cons. per m. into Exp/or. Mer., 31 .' 145-57. Cook, J. C. 1967. 'Scanning sonar and the fi shing industry' Ultrasonics I : 139·44. Seafood Export Journal Cushing D , . H . and F wit h in ~hR. H. Jones 1966 ' sonar'. J ce modulation se~t Sea trials 324.45 • on" Pa", In' E lor scanning Harding, Milson, . . xp or. M er, 30, D., E Sh M' reeve D . ummery 197i . s· Tungate and nlSm fo r th . A net chan' D. sampler Ibid ~J LoweS(of. M ,~g mecba· o • 483-91. U II-purpose T. ,B. and J. C . Installation . Cook 1971 . seClOr sea a,nd trials o f . Shipboard EI nnlflg s an elect <elronic E' onar. Th ronic IIgmeer, 41 (8) ' .: radio and . 339·350. Milson, R. B. and T. J transponding A Store to n- wcst (I I): 483-4 89, COUSIIC fish 1971. A Report of Voglis , G. tag Ibid" 41 the Direcior ]969-71 M.o~Marine Fish Fisheri:s . mISery of A ery Research of. 1973 /"heries LabOr;;"UI!"re and ebruary. ory. Lowest -M,andJ.C applications . ~OOk 1966. 'Und scannong e ." an advanced er ,,,,,er qurpment UllrCIS' acoustic olllcs 4.1-9. ~ ~ _", e""'" S·\·" ~ ~o' Sole d' . ENGINEERiN'bule,s " 5/195, PA~~~TERPRISES COCHIN ROAD Phone. 2;460 Manu! aelured b ROTAS~AL PACKA Vallabh V 'd GING Suja,a\. Indi'a vanagar, May, 1974 17 

Modern trends in fisheries technology in the United Kingdom

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Modern trends in fisheries technology in the United Kingdom

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