The enterprising small and medium

shrimp trawler operators of Kerala ventured

into deep sea fishing for the first time in

November 1999 defying the longheld concept

that deep sea prawn resources could be

harvested only by means of large trawlers.

This endeavour proved successful with the

realisation of 25,647 t of deep sea prawns in

the first fishing season lasting between

November '99 and May 2000

Chellappan, K

Nandakumar, G

Rajan, K N

CMFRI Digital Repository

Mar. Fish. Infoi: Serv.. T & E Sen. No. 170, 2001 TABLES. The C r u s t a c e a n r e s o u r c e s l anded (in tonnes . ) by the mu l t i day t rawl u n i t s d u r i n g 2000 at Mangalore fisheries harbour. Month April May November December Total Uni t s / Species g 105 130 220 463 Solenocera s p p . 25.9 9.5 21.5 -56.9 Arts (ens s p p . 0.9 64.3 30.3 34.6 130.1 Hetemcarpus .spp. -25.3 8.6 3.5 37.4 P a i a p e n a e u s s p p . --9.6 -9.6 Peurulns sewell l -24.7 0.6 25.3 Nephrop.sls stewartl -2.0 2.0 Total 26.8 99.1 94.7 38.7 259.3 Depth wise dis t r ibut ion of penaeid shrimps: Based on the analysis of data of crustacean landings of Mangalore fisheries harbour from the time of introduction of trawlers till date, depth wise distribution of shrimp resources along the Karnataka coast can be made. As per the exploitation pattern, the distinct zones that can be identified are the near shore water zone up to 50m depth, 50 to 150 m depth zone and the depth zone of 150 m and above. In the first zone, single day and multi day units are in operation and multi day trawlers mainly in the second zone In the third zone the trawling operation is up to 500 meter depth zone, which is at present exploited by large multiday trawlers of more than 56 feet OAL, equipped with facilities for deep sea operation. The major reason for the extension of activity was tha t the income from the conventional trawling operation is not adequate to meet the increase in operation cost. During first year of operation the result of deep sea trawling was encouraging and more and more fishermen modifying their trawlers to equip for deep sea trawling started operat ions. According to recent trend the deep sea trawlers from Mangalore are landing their catch in fishing harbours in Kerala, as the rate for the deep sea crus taceans are more and competitive. Another reason Is that most of the of deep sea trawlers are operating in the ground south off Mangalore and off Kerala coast and they are finding the harbours in Kerala nea re r to land the i r ca tch in fresh condition. Prepared by : A.P. Dineshbabu., B. Sreedhara and Y.Muniyappa. Mangalore Research Centre of CMFRI, Mangalore 975 Is the deep sea prawn fishery of Kerala sustainable? The enterprising small and medium shrimp trawler operators of Kerala ventured into deep sea fishing for the first time in November 1999 defying the longheld concept that deep sea prawn resources could be harvested only by means of large trawlers. This endeavour proved successful with the realisation of 25,647 t of deep sea prawns in the first fishing season lasting between November '99 and May 2000. The catch/hr of trawling was estimated as 53 kg against 6 kg of coastal species obtained for the Inshore prawn fishery during the same period. A detailed account of the fishery and biology of deep sea prawns of the period November '99 - March 2000 was given by Rajan etal. [(Mar. Fish. Infor. Seru.T&E Ser., 168, 2001). The deep sea prawn fishery in the second season of exploitation (2000-'01) was closely monitored to study the Impact of trawling on this resource and the present communication gives the result of this study. Fu tu re p rospec t s of th is Important commercial fishery along Kerala coast with possible management measu re s are discussed. Though trawling operations were mainly concentrated in the 'Quilon Bank', some of the trawlers based at Munambam and Kochi fisheries harbour carried out targeted fishing for the prime prawn species Aristeus alcoki (Red Ring) in deeper waters beyond 400 meters off Kanyakumari in the south and Beypore In the north. Some medium sized trawlers based at Mangalore shifted the base of operations to Kochi and concentrated on fishing for high priced 'Red ring'. In the last fishing season, one fishing trip generally lasted for 2 to 3 days whereas , in the following season (2000-2001) the fishing vessels stayed over 5 to 6 days per trip, mainly due to poor returns. Trawling operations commenced early in September, 2000 at Kochi, Munambam and Sakthikulangara-Neendakara. Because of the presence of juvenile prawns in large numbers in the fishery and consequent fall In prices, the industry voluntarily declared a ban on fishing in September and October. Regular operations commenced in November and continued upto March 2001 only. Deep sea prawn landings at Munambam, Kochi and Sak th iku langara -Neendakara together accounted for almost the entire fishery in Kerala. The landings at these centres accounted for 10,042 t, the catch/hr being 31 kg/hr of trawling (Table 1). 64.4% of the fishery was contributed by Sakthikulangara-Neendakara followed by 25.8% by Munambam and 9.8% by Kochi. M. andamanensis (33.60%) was the dominant constituent of the fishery followed by H. woodmasoni (25.46%), A.alcoki (15.33%), H. gibbosus (14.46%) and P. spinipes (9.15%). Other species such as P. martia, P.Jerryi, P. investigatoris and P. hextia were caught in small quantities. Data on size composition, sex ratio and breeding popula t ion of the dominant constituents were collected from all centres and the pooled data are presented here. Mar. Fish. Infor. Serv.. T i. E Sen. No. 170, 2001 Monthwise, species-wise and sex-wise data on size range, dominant size, sex ratio and breeding stock are presented in Table 2. Major depa r tu re s in the biological characteristics from the previous season (1999-2000) are as follows. H. woodmasoni : 51 to 130 mm size classes supported the fishery, whereas in the previous season sizes below 71 mm were totally absent. Size classes below 91 mm contributed to 19% of the overall fishery in this season, whereas in the previous season this group supported' only 2%. Percentage contribution of berried females in the total landings dechned from 79.3 in 1999-2000 to 56.5 in this season. H. gibbosus : The fishery was supported by 51-150 mm size classes in 2000-'01 season against 91-140 in the previous season. Juveniles below 100 mm in total length supported 9% of the fishery against 5% in the previous season. However, berried prawns were observed more in number in 2000-'01 season. P. spinipes : Size range of this species in the fishery during 2000-'01 season was 71-125 mm and sizes were almost similar in both seasons except a slight domination of Juvenile population (3%) in 2000- '01. Percentage contribution of berried prawns in the fishery declined from 73 in 1999-2000 to 57 in the present season. M. andamanensis : 66-135 mm sizes were represented in the fishery in 2000-'01 against 71-lOOmm sizes in the previous season. Prawns below 91 mm contributed to 48% of the fishery in 2000-'01, whereas in 1999-2000 season this size group formed only 26%. A. alcoki : The fishery was generally dominated by higher size groups between 131-175 mm in females against 126-150 mm in the previous year. Males above 100 mm were common in the catch in 2000- '01. Spawners formed 71% in 2000-'01 against 58.3% in the previous season. Deep sea prawn fishery in Kerala during 2000-'01 widely differed from the previous season (1999-2000) in catch, effort, catch rate, species composition and biological characteristics of component species. The overall catch in 2000-'01 heavily dechned by 15,605 t, over the previous season, the shortfall being 61%. The catch declined in all the fishing centres and the centrewise decline was 26% at Munambam, 77% at Kochi and 64% at Sakthikulangara-Neendakara. The overall catch/hr of trawling decreased drastically to 31 kg in 2000-'01 against 53 kg In the previous season, the percentage decline being 42. The catch rate also went down by 57% at Munambam, 61% at Kochi and 28% at Sakthikulangara. As the fishing days per trip was more during 2000-'01, the catch per boat tr ip showed a slight improvement of 13% over the previous season which is in the expected lines. The overall fishing effort in terms of trawHng hours in 2000-*01 declined by 33%. The centre wise decline was 41% at Kochi, 49% at S a k t h i k u l a n g a r a - N e e n d a k a r a . However, at Munambam the effort improved by 73%. Fishing operations in 1999-2000 extended upto May whereas, in the following season the activit ies ceased by March because of fall in prawn catch. The catch of all deep sea prawn species declined in 2000- '01 season , with the shortfall more pronounced in pandalld prawns. H. woodmasoni landings declined by 73%. P. spinipes by 86% and H.gibbosus by 66%. In penaeid prawns the decline was only marginal and catch of M. andamanensis and M. alcocfci declined by 3 and 10% respectively. Targetted fishing for the prime species of A. alcoki in deeper waters off Kanyakumarl has yielded good returns for trawlers based at Munambam. Mar. Fish. Infor. Sen., T & E Sen, No. 170, 2001 Species composition of deep sea prawn fishery in 2000-'01 showed wide fluctuations in comparison with the previous season (Flg.l). Pandalid prawns contributed to 78% of the deep sea prawn fishery In 1999-2000, major contr ibutors being H.woodmasoni (37%), P. spinipes (26%) and H. gibbosus (15%). The contribution of pandahd prawns in 2000- '01 declined to 49%. Both H.woodmasoni (25%) and P. spinipes (9%) registered heavy decline in the percentage cont r ibut ion whereas , the share of H. gibbosis remained almost the same in both seasons (14%). Penaeid prawn M.andamanensis contributed to 34% of the fishery in 2000-"0I against 14% in the previous season. The share of A.alcoki improved by 9% in the present season mainly •due to operation of some of the boats in deeper grounds beyond 400m off Kanyakumarl and Beypore targeting for larger varieties of deep sea prawns. Species * Flg.l Specieswlse percentage contribution of deep sea prawns fishery of Kerala during 1999-2000 Pandalld prawn fishery in 1999-2000 was mostly supported by adult prawns. But in Mar. Fish. In/or. Sen:. T & E Ser., No. 170. 2001 the following fishing season of 2000-'01, juveniles were present in good numbers and they formed 19% of the fishery in H.woodmasoni, 9% in H.gihbosus and 24% in P. spinipes. Percentage contr ibut ion of berried prawns declined by 22.8% in H. woodmasoni and 15.6% in P. spinipes. In the case of penaeid prawn M. andamanensis juveniles formed 48% of the fishery. While discussing the future prospects of deep sea prawn fishery along Kerala coast it is predicted that the catch rate are likely to decline in the ensuing season due to the virgin nature of the fishing ground and the biological limitations, such as slow growth rate, low fecundity and long life span of deep sea prawns. Drastic reduction in the overall catch and catch rate in the deep sea prawn fishery of 2000-01 season, heavy decline in the con t r ibu t ion of panda l id p rawns , abundance of juveniles in pandalid as well as penaeid prawn catch and decline in the percentage composition of berried prawns, concretely point out that the deep sea prawn stock is facing over exploitation in the second year of the fishery itself. The fishing pressure is to be drastically reduced by minimis ing the n u m b e r of t rawlers opera ted for deep sea prawn fishery. Attempts should be made to explore new trawling grounds beyond the intensively exploited 'Quilon Bank'. Availability of the prime species , A.alcoki in fairly large quantities for a few vessels in deeper waters off Kanyakumar i and Beypore is an encouraging trend in this direction. Deep sea prawns are easily susceptible to spoilage. Except hard shelled Heterocarpus species, all other prawns were landed in partially spoiled condition after long fishing trips. Post harvest technology should be upgraded for on board preservation of the deep sea prawns to maximize the profit to this industry which is facing a crisis due to depletion of the stock. TABLE 1. Details of deep sea prawn fishery along Kerala coast during 1999-2000, 2000-2001 Particulars No. of Ixiat tr ips Trawling hrs . Deep sea prawn catch [t] Catch/ lxia t trip (kg) Ca t ch /h r (kg) Specleswise catch (t) Heterocarpus woodmnsarii H. gUjtjosus Plesionika spin ipes P. martia Arisleus alcukl Metapenneus (uuiiinifmerisis Penaeopsisjerryi Ptwipeniieus iiiuestiyoiiirui Soleruxera liextii Nov. '99-Mar. '00 2949 60090 3 4 8 3 1181 5 8 1193 (34.3%) 5 0 5 (14.5%) 1131 (32.5%) 14 (0.4%) 164 (4.7%) 450 (12.9) 23 (0.6%) 3 (0.1%) Munambain S e p . 2 0 0 0 -Mar. '01 2 3 3 7 104187 2 5 9 1 1109 2 5 4 3 8 (10.9%) 289 (11.2%) 5 5 0 (21.2%) 8 (0.3%) 309 (14.2%) 709 (29.7%) 160 (6.2%) 8 (0.3%) KochI fisheries harbour Sakthlkulani>.ini N o v . 1 9 9 9 -Mar. 00 3051 6 9 9 9 5 4348 1191 62 1582 (36.4%) 779 (17.9%) 974 (22.4%) 1(0 037 (14.7%) 289 (0.6%) 14 (0.3%) 72 (1.7%) .Sep . 2 0 0 0 IVlar. '01 1004 41311 982 9 2 3 24 171 (17.4%) 258 (20.3%) 98(10 .0%) 4 (0.4%) 234 (23.8%) 198 (20.29%) 19 (1.9%) N o v . 1 9 9 9 -M a r . ' 0 0 28434 357102 17816 027 50 0000 (37.4 1%) 2.547 14.30%) 4539 (25.48%) 02 (0.35%) 910 (5.11%) 2739 (15.37%) 251 (1.41%) 102 (0.57%) .Sep. 2 0 0 0 Mar. 01 9112 181091 6409 710 36 1948 (30.11%) 905(13.99%) 2 7 1 (4.19%) 936 (14.4%) 2407 (37.21%) 2 (0.03%) • Total 1999-2000 2000-'01 35034 4 8 7 1 9 3 25647 732 53 9441 (30.81%) 3831 (14.94%) 6044 (25.9 1%) 77 (0.30;%) 1711 (0.07H)) 3478 (13.50%) 288 (1.12%) 177 (0.09%) 12513 32U589 10042 803 31 2557 (25.40%) 1452 (14.46%) 919 (9.15%) 12 (0.12%) 1539 (15.33%) 3374 (33.G0"/<,) 179(1.78%) 8(0.(18%) 2 (0.02%) No tnwUnf In October 2000 Mar. Fish. Infor. Sen., T & E Sen, No. 170, 2001 TABLE 2. Biological characteristics of deep sea prawns Male Female Sex ratio (%) Heterocarpus woodmasonl Sep. 2000 Nov. 2000 Dec. 2000 J a n . 2 0 0 1 Feb. 2001 Mar. 2001 Total Heterocarpus gihbosus Sep. 2000 Nov. 2000 Dec. 2000 Jan. 2001 Feb. 2001 Mar. 2001 Total Plesioi\ikasplnlpes Sep. 2000 Nov. 2000 Dec. 2000 Jan. 2001 Feb. 2001 Mar. 2001 Total S i z e r a n g e (mm) 6 6 - 1 2 5 7 6 - 1 2 0 5 1 - 1 2 5 6 6 - 1 2 0 8 1 - 1 2 5 6 6 - 1 3 0 51 -130 9 1 - 1 2 5 7 6 - 1 2 5 9 1 - 1 3 0 8 1 - 1 5 0 9 1 - 1 3 0 5 1 - 1 3 0 5 1 - 1 5 0 7 6 - 1 1 0 8 1 - 1 1 0 7 1 - 1 1 0 7 1 - 1 1 5 7 1 - 1 1 5 7 1 - 1 1 5 7 1 - 1 1 5 Metapenaeopsis andumanensis Sep. 2000 Nov. 2000 Dec. 2000 Jan. 2001 Feb. 2001 Mar. 2001 Total AristeusfiicoM Dec. 2000 Jan. 2001 Feb.2001 Mar. 2001 Total 6 6 - 1 0 5 7 6 - 1 1 5 71 -130 76 -130 6 6 - 1 2 5 76 -125 6 6 - 1 3 0 81 -115 8 1 - 1 0 5 8 1 - 1 0 0 76 -115 76 -115 D o m i n a n t s i z e (mm) 106-120 9 6 - 1 1 5 9 6 - 1 2 0 9 1 - 1 1 0 101-120 101-120 9 6 - 1 2 0 106-120 9 6 - 1 1 5 106-120 101-125 106-125 101-125 9 6 - 1 2 5 9 1 - 1 0 5 101-110 8 1 - 1 0 5 9 1 - 1 0 5 8 6 - 1 0 5 8 1 - 1 0 5 8 1 - 1 1 0 8 1 - 9 0 9 1 - 1 1 0 7 6 - 9 5 8 6 - 1 0 5 8 1 - 1 0 0 8 1 - 1 0 0 7 6 - 1 0 5 8 6 - 1 1 0 9 1 - 1 0 0 9 1 - 9 5 8 6 - 1 1 0 8 6 - 1 1 0 S i z e r a n g e (mm) 6 6 - 1 2 0 6 6 - 1 2 0 56 -125 76 -125 76 -125 66 -130 56 -130 101-135 81 -140 91 -140 76 -140 91 -145 56 -130 56-145 81 -115 91 -115 81 -120 8 1 - 1 1 5 8 1 - 1 2 0 71 -125 71 -125 71 -115 8 1 - 1 3 5 71 -130 76 -130 6 6 - 1 3 0 76 -130 66 -135 106-190 116-180 126-185 116-190 106-190 D o m i n a n t s i z e (mm) 106-120 9 6 - 1 1 5 66-80 & 101-105 106-120 101-115 106-125 9 6 - 1 2 0 116-130 101-125 106-125 106-135 111-130 106-130 101-135 3 6 - 1 1 0 9 6 - 1 0 5 9 6 - 1 1 0 9 1 - 1 0 5 9 1 - 1 1 0 8 6 - 1 1 5 8 6 - 1 1 5 8 1 - 9 5 8 6 - 1 0 5 7 6 - 1 0 0 9 1 - 1 2 0 8 1 - 1 0 5 8 1 - 1 0 0 7 6 - 1 2 0 131-160 151-170 146-170 141-175 131-175 M a l e 5 3 . 9 50 .4 48.1 2 7 . 5 57 .8 4 9 . 5 50 .2 6 2 . 5 4 4 . 6 54 .4 4 7 . 0 47 .1 3 8 . 3 4 6 . 6 48 .2 4 6 . 7 4 5 . 8 4 2 . 9 3 5 . 8 43 .2 4 2 . 6 4 0 . 6 ,36.8 4 5 . 6 3 9 . 7 4 4 . 0 4 1 . 7 43.1 13.3 11.5 16.3 10.8 12.5 F e m a l e 46.1 49 .6 51 .9 72 .5 42 .2 50 .5 49 .8 37 .8 55 .4 45 .6 53 .0 52 .9 671 .7 53 .4 51 .8 53 .3 54.2 57.1 64 .2 56 .8 57 .4 59.4 63 .2 54 .4 6 0 . 3 56 .0 58 .3 36 .9 86 .6 88 .5 83 .7 89 .2 87 .5 B e r r i e d f e m a l e s (%) 73 .4 42 .4 3 3 . 7 51 .7 79 .6 61 .9 56 .5 17.6 19.4 25 .0 43 .7 76 .9 77 .3 58 .0 56 .8 3 1 . 3 57.1 77 .6 7 3 . 6 28 .5 47 .7 -1.3 3 .3 4 .9 1.0 2.5 72 .4 8 7 . 0 66 .7 65 .7 71.1 976 Prepared by : G. Nandakumar, K.N. Rajan and K. Chellappan, Central Marine Fisheries Research Institute, Cochin Expedmentfil productioxi of half pearls from tropical abalone Haliotis varia (LitinO at Mandapam Abalones are one among the few molluscs known for producing gem quality pearls and highly priced meat. The nacre of abalone shell is often multihued in tunes of silver, orange, pink, green, blue and lavender. The abalone pearls are superior to pearls produced from freshwater mussels and comparable to best marine pearls. History of abalone pearls dates back to 5000 BC. The first recorded reference occurs In one of the Japanese oldest historical writing, the Kojiki. (ca 800 AD). Production of pearls from cul tured abalones is of recent 

Is the deep sea prawn fishery of Kerala sustainable?

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Is the deep sea prawn fishery of Kerala sustainable?

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