In north Kerala region, a widespread and high density

bloom of Chattonella marina occurred in the first

week of September 2002. The bloom showed a

discontinuous distribution and extended over a

distance of about 50 kilometers along the coast, from

Konadu near Calicut to Mahe near Thalassery

Jugnu, R

Kripa, V

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C M Y K10 Marine Fisheries Information Service T&E Ser., No. 195, 2008Table 2Landings of prawns during 2006Name of Landings (kg) Bottom PriceSpecies Trawl set Gillnet (Rs. Innet gillnet lakhs)Metapenaeusaffinis 88,772 9,223 3,929 149.1M.dobsoni 87,111 0 491 70.1M. lysianassa 280 0 0 0.2M. monoceros 41,593 0 0 60.3Metapenaeopsisstridulans 175,857 0 0 49.5Parapenaeopsishardwickii 126,348 0 0 55.3Penaeus indicus 9,015 0 0 18.0P.japonicus 23,362 0 0 45.3Parapenaeuslongipes 37,532 0 0 7.5P.merguiensis 424 5,516 1,586 19.4P.monodon 12,378 2,170 0 64.6P.penicillatus 16,299 700,136 0 1791.1P. stylifera 31,505 0 0 14.2Solenocera crassicornis 66,794 0 0 30.1Others 285 4,014 0Total 717,555 721,059 6,006 2374.4More than 60 fin fish species and nearly 20crustaceans including 15 prawns were found in Purilandings during 2006.The first sale value of P. monodon was in therange Rs. 400-500/- per kg., and during 2006 theamount realized from this particular species was morethan 64 lakh rupees (Table 2). The landing centreprice of M. dobsoni was consistent throughout theyear with an average Rs. 80/-per kg. Prices of  Johniusdussumieri, Otolithes ruber and Caranx ignobilis werealso consistent throughout the year.P. merguiensis and P. penicillatus were mainlycaught by bottom set gill nets whereas all the othervarieties were the main stay of trawl nets.Catfishes, eels, sharks, perches, carangids, seerfishes and tunnies were the main resources found inthe hooks & lines catches. Prawns, big jawed jumper,ribbon fishes, croakers, clupeids and cat fishes werefound in good quantities in trawl catches. Wolf herring,anchovies, other sardines, other clupeids, horsemackerel, pomfrets, seerfishes, mullets and crabs aremaximum in drift/gill net catches.Scomberomorus commerson, S. guttatus, Ilishaelongata, I. melanostoma, Lutjanus johni, Formioniger, Pomadasys hasta, Epinephelus chlorostigma,Pampus argentus, P. chinensis, Mugil cephalus,Tenualosa ilisha, Eleutheronema tetradactylum,Chirocentrus nudus are the commercially importantfish species. Arius tenuispinis is the only cat fishavailable in Puri district.Fishing was interrupted by heavy rains andcyclonic weather conditions every year. In almost allmonths, juveniles of  penaeid prawns likeParapenaeus longipes, Metapenaeopsis stridulans,non-penaeid prawns like Nemato-palaemon tenuipesand pomfrets were found in trawl catches at Nuagarhlanding centre.Chattonella marina blooms and its impact on the coastal fishery resourcesalong north Kerala coastJugnu, R.and  V. KripaCentral Marine Fisheries Research Institute, KochiIn north Kerala region, a widespread and high densitybloom of Chattonella marina occurred in the firstweek of September 2002. The bloom showed adiscontinuous distribution and extended over adistance of about 50 kilometers along the coast, fromKonadu near Calicut to Mahe near Thalassery. Themuddy green coloured bloom was very noticeable atKappad, where it extended from the shoreline to abouta distance of about 3 kilometers towards the sea. Itwas visible as streaks and patches in other areas.11Analysis of phytoplankton in the bloom regionshowed a very high density of C. marina, 28x107cells l-1 at Kappad on the first day of the bloom. Highdensities of few other phytoplankton were alsoobserved and these included Coscinodiscusasteromphalus at a density of 8x104 cells l-1,Pleurosigma normanii at 2x104 cells l-1 and Noctilucasigma at a density of 4x104 cells l-1. By eighth day,density of C.marina had decreased considerably to4234 cells l-1. C.asteromphalus (1312 cells l-1),P.normani (22 cells l-1) and N. sigma (552 cells l-1)were the other species of phytoplankton present. Thedensity of the harmful algae had reduced to 2200cells l-1 after three weeks, while the  density ofC.asteromphalus had increased to 38,400 cells l-1,P.normanii to 164 cells l-1 and Noctiluca sigma to 235cells l-1.The density of C. marina was very low at Konaduwhen compared to that of Kappad. On the first dayC.marina was present at a density of 40,000 cells l-1along with the diatom C.asteromphalus at a densityof 8100 cells l-1 and N.sigma at 120 cells l-1. By theeighth day the density of harmful algae had decreasedsharply to 2815 cells l -1, while the diatomC.asteromphalus increased to a density of 13,200cells l-1. P.normani at a density of 1350 cells l-1 andN.sigma at 5500 cells l-1 were the other diatomspresent. On the 22nd day C.marina was present atvery low densities of 480 cells l-1. The density ofC.asteromphalus had increased to 45600 cells l-1,P.normani to 1730 cells l-1 and N.sigma to 12,500cells l-1.C. marina was not present at Chombala duringthe first week. By the second week C.marina bloomwas noticed at this site and phytoplankton analysisshowed that it was present at a high density of1,70,000 cells l-1. The harmful alga Noctilucascintillans was also detected at a density of 100 cellsl-1. C.asteromphalus at a density of 24700 cells l-1,P.normani at a density of 2300 cells l-1 and N.sigmaat a density of 8100 cells l-1 were the other algaepresent. Sampling on the 14th day showed that theconcentration of the harmful algae had decreased to2990 cells l-1, N.scintillans to 60 cells l-1 and that ofC.asteromphalus to 2800 cellsl-1 at the site. P.normaniiand N.sigma were also present in the sample, but atvery low densities. In September 2003 the bloom wassevere with maximum cell density of 135 x 105 cells l-1  but  was for a short period of 5 days.A very low dissolved oxygen value of 0.22 mg l-1was recorded on the 1st day at Kappad  which slightlyincreased to 1.66 and 1.86 mg l-1 on the 8th and 22ndday.The dissolved oxygen content at Chombaladuring the bloom period was low, of 1.92 mg l-1 whichincreased to 3.52 mg.The catch from the fishing crafts operating in theCalicut region are landed in the two major harboursnamely Chombala and  Puthiyappa and in the 3 majorlanding centers ( Koyilandy, Thikkodi and Kuriyadi)and 12 minor landing centers (Kappad, Edakkadavu,Kavalad, Koloth, Moodadi, Muthaya Kadappuram,Valavil Kadappuram, Payyoli, Kolavi, Badagara,Madappaly and Mahe). The landing from all thesesites using gears viz. outboard trawl net (hand trawl)(OBTN), outboard drift net (OBDN), outboard  ringseine (OBRS), outboard gill net (OBGN), and countrycraft gill net(CCGN)  were used for the study. Thesegears generally operate within a distance of 55 kmfrom the shore.Fishery was found to be affected during theblooming of C. marina along the Calicut coast.Reduction in catch from all the gears was observed.During the prolonged bloom of C. marina along theCalicut coast, a shift in the community structure witha dominance of fishes belonging to higher trophiclevels was observed. Species which were mainlyzooplankton feeders were entirely absent and theseincluded Stolephorus spp, Thryssa and Leiognathuswhich in turn resulted in the reduction in catch of thegroups which mainly fed on these zooplanktonfeeders such as Caranx spp. and Johnius spp. Asignificant change in fishery was an increase in catchof the predatory fishes mainly, Euthynus, Trichurus,Carcharinus, Saurida, Scoliodon, Scomberomorus,and Sepia spp which occupies the topmost trophiclevel. The catch per unit per day for Cynoglossus,Johnius, Thryssa and P. stylifera in the outboard trawlnet showed significant variation (P<0.05), whereasM.dobsoni, Penaues indicus did not show anysignificant variation (P>0.05). The landing ofEuthynnus spp. in outboard drift net was high duringthe bloom period from that of the nonbloom periodand the variation in CPUE was significant (P<0.05).Demersal fishes Arius, Muraenosox, Priacanthus,Pristipomoides spp and the ray Himantura sppoccurred in the fishery only during the bloom period.Chattonella marina blooms and its impact on the coastal fishery resources along north Kerala coast12 Marine Fisheries Information Service T&E Ser., No. 195, 2008The clupeid Albula vulpes and the sailfish Istiophorusoccurred in the period prior to the bloom, the formerduring the first instance of Chattonella marina bloomand the latter during both the blooms.Taxonomic diversity studies indicated a changein the community structure of commercial finfishes,crustaceans and molluscs due to the bloom ofC.marina. Though the species numbers did not varybetween the bloom and the non bloom period, thetaxonomic distinctness differed indicating a changein the community structure. Funnel plots indicated thedeviation in taxonomic distinctness during the bloomperiod from the theoretical mean for the region.Significant variations were observed in the bloommonth of September 02 and more in the post bloommonth of October 02. The effect of the bloom on thefishery appeared to be temporary reviving soon afterthe subsidence of the bloom. However, the economiclosses were high in the year in which the bloom wasprolonged since the fishermen abstained from fishingdue to the absence of fish shoals and low fishabundance.Subsequent to this, mass mortality of greenmussels of the region was also observed. Besidesfishes and mussels, the mole crab Emerita sp. wasalso found to be severely affected and these werefound washed ashore all along the Kappad beach on4/9/02. At Chombala, the shells of the bivalve Mactraviolacea with decayed meat was found washedashore in large numbers on 13/9/02.A report on the mass mortality of farmed shrimp due to the blooming ofChattonella marina along Vypin coastR. Jugnu and V. KripaCentral Marine Fisheries Research Institute, KochiChattonella marina which blooms regularly alongthe Calicut coast bloomed for the first time inthe coastal region along Vypin, Cochin in September2003. The bloom extended to a distance of about 1kmfrom the coastline covering a distance of 3km fromPuthuvypin to Malipuram. The greenish browncoloured bloom was noticed in the second week ofAugust in the coastal waters and adjacent farms ofthe area. Bloom subsided in the coastal waters onthe third day itself, but in nearby fish ponds it remainedin the bloom condition till the end of the month.Sampling was done on alternate days, from the daythe bloom was observed at sea (19/9/03) till the endof the following month until the normal flora wasrestored.The phytoplankton collected from the sea wasdominated by C.marina on the 1st and 3rd day afterwhich the diatom Coscinodiscus sp. becamedominant. Count of C.marina on 1st day was 2,40,000cells l-1 which decreased to 17000 cells l-1 on the 3rdday and was absent in the subsequent samplings.Coscinodiscus sp. present at 98 cells l-1 on the 1stday, increased to a density of 137 cells l-1 by 23rd day.A higher density was noted in the farm whencompared to that of sea. The density which was4,68,000 cells  l-1, on the 1st day decreased to 40,000cells l-1 by the 3rd day. On the 5th day, it again increasedto 2,00,000 cells l-1 but there were isolated patches inthe ponds which received bright sunlight where C.marina had concentrated in very high numbers. Bythe 7th day, Peridinium sp. had become dominantwhose density increased to 1400 cells l-1 by the 23rdday of the bloom.Temperature seems to play an important role inretaining the bloom condition. The results of theanalysis of physicochemical and biologicalparameters measured at the two sites is given inTable. Chl a, b, c and carotenoids values were higherat sea in the 1st, 3rd and 5th day and varied between55.9 and 73.7 mg m-3 for Chl a, 0 and 23.81 mg/m3for Chl b and between 5.89 and 21.58 mg m-3 for chl cand between 0 and 1.244 mg m-3 for carotenoids. Onthe 7th, 9th and 23rd day Chl a varied between 1.1 to7.89 mg m-3. Chl b at the site varied between 0.61

Chattonella marina blooms and its impact on the coastal fishery resources along north Kerala coast

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