preliminary survey report on the hydrobiology and fisheries of nagarjunasagar, andhra pradesh PDF
Preview preliminary survey report on the hydrobiology and fisheries of nagarjunasagar, andhra pradesh
PRELIMINARY SURVEY REPORT ON THE HYDROBIOLOGY AND •• FISHERIES OF NAGARJUNASAGAR, ANDHRA PRADESH Survey Report No. 5 June, 1969 • INDIAN COUNCIL OF AGRICULTURAL RESEARCH CENTRAL INLAND~ FISHERIES RESEARCH INSTITUTE BARR~CKPORE. WEST BENGAL IN D I A PRELIMINARY SURVEY REPORT ON THE HYDROBIOLOGY AND FISHERIES OF NAGARJUNASAGAR~ ANDHRA PRADESH by A. David & Staff of the Tank Fisheries Unit, Bangalore Survey Report No. 51i -+' June ~ 1969 INDIAN COUNCIL OF AGRICULTURAL RESEARCH I CENTRAL INLAND FISHERIES RESEARCH INSTITUTE INDIA BARRACKPORE, IVEST BENGAL, ii' ·PRELJMINARX SURVEY REPORT. OR ·THE HYDROBIOIDGY AND FISHERIES OF NAGARJUNASAGAR, ANDHRA PRADESH by A. David ,'.'! , .. & "StafL of the Tank Fisheries' ~nit·,fBangalore .1' I ; CONTE~"T9 1 INTRODUC,T ION 2 DESQRIFTION OF'~HE RESERVOIR HYDROGRAPHICAL FEATURES 3. 4" 'HYDROBIOtOG rcAL CONDIT IoiJS )O~ THE RESERVO IE ,. \ <. . 4.1 -, Hydrologi~al cQnGlitions" . , 4.1 :1" Phys:(co-chem:L.calconditions of water 4.1.2 Soil phase 4.2~· Biomass structure 4.2.1 Vegetation ': 4~2.2 Benthic ~nd littoral biota 4.2 .3 Plankton 5 FISH AND FISHERIES , L 5 •1 Fish fauna 5.2 Commercial fishing 5.3 Estimated fish production 5.4 Experimental fishing 5 •4•1 Gear efficiency 5.5 Canal fisheries 6 RETvIimKS 7 RECOMIVIEJ\1])EDDEVELOPME:NTAL MEASURES 8 RECONIt1S1IDED RtSEARCH PROGRArvIMES 9 SUMMARY -2- 1 INTRODUCTION Nagarjunasagar is proposed to be the main co-ordinating centre under the Co-ordinated Research Project Programme of the ,Indian Council of Agricultural Research to be undertaken during 1969-74 by the Centra~ Inland Fisheries Research Institute jointly with the Directorate of Fisheries, Andhra Pradesh, for "3tudies on the ecology and fisheries of fresh water reservoirsfl• Proper development of the fisheries of 300 and odd reservoirs in India can perhaps best be done by a detailed study of the behaviour of fish population under the diverse ecological conditions obtaining in selected reservoirs. Though preliminary experimental and developmental measures have led to increased fish production in certain reservoirs, in view of the varied results obtained from place to place, it has so far not been possible to formulate standard developmental techniques and recommend management practices based on the ecology of the reservoirs. With a view to developing the fisheries of the reservoirs to the best possible extent, such studies are intended to be initiated to start with in Nagarjunasagar in Andhra Pradesh~ Bhayanisagar in Tamil Nadu and Rihand Dam in Uttar Pradesh. Preliminary investigations of Nagarjunasagar were conducted during 12.2.1969 to 12.3.1969 by the author with the help of members of the staff attached to Tank Fisheries Research Unit of the Institute at Bangalore for assessing the fishery potential and for formulating a resea~ch programme taking into congnizaBce the exi~ting conditions of this reservoir. Information on various. hydrographical, hydrobiological and fishery potential of Nagarjunasagar, presen- ted here, were collected by actual field ir.vestigations. The reservoir, being a deep one, presents certain unique features which require special consideration in drawing a technical research programme. 2 DESCRIFT ION OF THE RESERVOIR Nagarjunasagar reservoir is formed as 'a result of impoun ding the waters of the .iJerennialriver, Krishna, 'traversing tr.e deep ravines of the Nallamalai hill ranges, at a place half-a mile downstream of Nandikonda village (now submerged) in J'lIir;ralgudTaaluk of Nalagonda district of Andhra Pradesh. It is situated at Latitude 16°34' North and Longitude 79°19' Easto The impoundment of the reservoir was, started in 1962, after the closure of construction sluices. The concrete type dam is 367 ft (111.86 m) high with a length of 4,756 ft (1,447.6 m), with a non-overflow masonry dam of 3,211 ft (978.7 m) comprising both right and left flanks. -3- The left earthen dam is 8,400 ft (2,560.3 m) in length and the right one 2,800 ft (853.4 m). SeasonalPeddavagu and Dindi are the two streams draining into the reservoir during floods. The reservoir has a maximum water spread area of 110 sq miles (28,490 ha')at full level (i.e. at E.L. 590) when the water storage capacity' would be at 9.3 m. ac. ft. (4,05,201 m.c.ft.). While the live storage is 5.47 m.ac.ft. (2,38,327.9 m.c.ft.), the'minimum or dead-storage is assessed to be 3.8 m,ac.ft. (1,65,566 m.c.ft.), which implies that the storage potencial of the reservoir is the highest of any reservoir in India and even at dead storage, the reservoir is the deepest in India (150 ft or 45.72 m). The reservoir is,situated in a deep ravine 60 miles (96 lan) long with abrupt margins at a slope of 45-60°. ~ving to ravinous nature of the terrain, rise in water level can only be noticed in depth variations, the extended shallow areas being greatly limited exhibiting restricted inundated margins. -Since an average depth of 197.7 ft (60.35 m) is observed (at level E.L. 531) right from the reservoir'portion to the origina~ river junctio~ (tail end) extending upto Srishailam, shallow areas totallinG 5-8 sq miles are limited and restricted to bay like extensions in pockets at Peddamonagal, Right Bank extension (Shinkishela) and Eleswaran (Fig. 1). The total length of the reservoir at full reservoir level (E.L. 590) is about 60 miles (96 km) extending right upto Srishailam where a dam is under const~uctiono During the survey period, when the reservoir level stood at E.L. 513.82, the,lacustrine limit extended upto a point'3 miles (4<,8kIn) downstream of Srishailam. The river descends at this point from a considerable height through rapids. The~e are two tributaries of the Krishna, the Dindi and Peddavagu, both of minor importance, Dindi being a seasonal river and Peddavagu a seasonal stream (Fig. 1). Only the Nagarjunakonda, Peddamonagal and Shinkishela B~ys are accessible by road. No other portion of the reservoir is approachable, owing to the deep ravines, except through water. -4- 3 HYDROGRAPHICAL FEATURES Meteorological conditions of the reservoir appear to be unlike Tungabhadra reservoir. The reservoir is free from wind and wave action for maj,or part of the year. The reservoir comes under the influence of the south-west monsoon and receives rain during the period June/July-August. The mean annual rainfall of the area is 35" (87.5 cm), with a catchment area of 83,087 sq miles (2;15,19,533 ha). The silt-laden inflowing rain'water'has already resulted in the deposition of, 60-70 ft (18.29-21.33 m) of silt in the reservoir. ~TIile the minimum discharge at the dam site during dry weather is estimated at 100 cusecs, the maximum discharge so far observed was 11,70,000 cusecs in 1964 (Table 1). Major influx of water into the reservoir comes from the main I~ishna river. The quantities brought in by the two tribu taries, the Dindi and Peddavagu appear to be low, their actual inflows having not been assessed. The average draw- down of water is 4H (10 cm) per day through the two right and left canals and the diversion tunnel, which regulates the water supply to the river below the dam for deltaic cultiva tion of the Krishna. This draw-down will probably increase after the installation of 8 generators is completed. 4 HYDROBIOLOGICAJ-lCONDITIONS OF THE RESERVOIR Division of the reservoir into distinctive zones as in Tungabhadra reservoir, such as deep, transitional, shallow, .and riverine portions, is not possible owing to the uniformly deep and ravinous nature 6f the reservoir' resembling in this respect the Gohindasagar Reservoir of the Panjab (Bhakra-. Nangal). Hence l~ttoral and benthic features of the reser;roil' are not distinct;- However, in ordert 0 have a preliminary understanding of the bioge.nic factors and their interactior..~ 9 stations, covering the major part of the reservoir, were arbitrarily selected for hydrological an.1"<:iological observations and experimental fishing. The centres so chosen were : I. Reservoir portion Max. D~th ft) 1. Pump House 60 m (196.8 2. Pylon Colony 56 m (183.0 f't;) ft) 3. Mid Reservoir 65 m (213.3 4. Nagarjunakonda 60 m (196.8 fOG) -5- II. Bays 5. Shinkishela 5.m (16.4 ft) 6. NagarjunakondaBaY30m (98.5 ft) 7. Peddamonagal 5 m (16.4 ft) 8. Eleswar.am 2 m ( 6.6 ft) III. Tail-end 9. River joining 60 m (194.8ft) point 4.1 Hydrological conditions 4.1.1 Physi~o-chemical conditions of water . At most' of the stations, samples from surface to 10-20 m at 5 m intervals, were collected. In the bays, only surface.and bottom collections were made. The rianngTeasblein2.the various chemical constituents o'f water'are shown It was observed that~bathymetric temperature variation is not significant indicating non-existence of a thermocline. poHf 4o8f.0t-h1e57w.a0termg/ils,ownitthhehaarldknaelsisne vasriydien.g Tfhreomal2k9a.l6i-n1i0t9y.2 ramng~/el, indicates moderate bicarbonate hardness and a congenial medium for the subsistence of fish life. Dissolved oxygen concentration (5.28-8.0 mgj~) is at a satis~actory level. Specific conductivity values (383-536 x 10- mhos at 25°C) reveal fair concentratiop. of dissolved salts. The values are almost at par with those of corresponding months in the Tungabhadrareservoir. The nutrients-phosphate and iron are poor but nitrate is comparatively high. Primary productivity values ranged from 250.0 to 709.2 mg C/m3/day (10.46 to 29.54 mg C/m3/hr). Dam site (Pump House), Pylon Colony (with algal patches) and Peddamonagal exhibited ,greater numbers (concentration/density) ofphytoplankters and showed correspondingly higher productivity values. In view of high clarity of water and favourable temperatures with relatively denser phytoplanktony gross productivity was obser ved to be more at 5-10 m depths at almost -all the centres of obseJ;'vationsthan at surface and deeper layers. -6- 4.1.2 Soil phase Chemica~ conditions of soil are spown in Table 2Al - It is seen that the soil pH ranges from 7.2 to 7.6 showing neutral to slightly alkaline reaction. Available phosphorus is extremely poor at all sampling centres except that of Pylon colony (11.8 mg/100 gm) and Eleswaram (3.8 mg/100 gm) where it is fairly high and medium respecti vely. The soil is comparatively rich in nitrogen content except at Dam site (0.04 mg/100 gm) and River mouth (0.04 mg/100 gm). Total nitrogen is highest at Nagarjunkond? (0.22 mg!100 gm), where organic carbor),is-also maximum (2.42%). Like soil phase, corresponding water phase (Table 2),h~s shown extremely low phosphate (Traces - 0.006 mg/l) and fairly high nitrogen content (0.08-0.20 mg/l). In general, organic carbon and exchangeable calcium range from medium to high values. C/N ratio at each centre is within a favourable limit (8.3-11.0) except that at River mouth (19.8 where it is com- paratively wide. ~ Based on soil characteristics, the fertility status at each centre is indicated in Table 2A. 4.2 Biomass structure 4.2.1 Vegetation The reservoir, being ravinous and full of rubbles and stones with precipitous banks, appears to be devoid of higher aquatic vegetation. Even in the shallower bays, save for algal filamentous formations, no vegetation of higher types was noticed •. ' Algae are found along the margin at Pump House and Pylon Colony side areas. Floating scwn and algae found along the margins, consisted of Mougeotia (75%), Oscillatoria' (15%), Oedogonium and Spirogyra (10% )on the Pylon Colony side 'and the scrapings from submerged substrata revealed diatoms comprising Synedra, Fragillaria, Tabellaria, etc. Sparse algae formation along the Pump House marginal areas consisted only of Spirogyra. Dislodged algal filaments contribute to the food source for fishes at these places. Microcystis concentration was significant at Peddallonagal Bay area. It occurred in stray numbers in Nagarjunakonda. -7- 4.2.2 Benthic and littoral biota Benthic and Iittoral biotal composi tion is, very poor comprising only chironomids in stray numbers in the silty benthic areas of the origianal river course. Bottom and littoral areas being sandy in other places, invertebrates are virtually absent. Insect life is very poor. Sparse insect life mainly comprising corixids (Corixa sp.) was observed at Eleswaram Bay region and mayfly nymphs at Peddamonagal area, the only areas where some kind of bottom organisms were recorded. Very rarely ~ncount~red dead gastropod molluscan shells indicate the occurrence of such forms as Pleurocera, Gyraulus, Horatia (?), etc., in Peddamonagal area. Peddamonagal, with disintegrating organic mucbJ bottom7 may serve as sustaining ground for mulluscan fauna at a later stage. 4.2,,3 Plankton Table 3 indicate s group-wise plankton consti tuents at various centres of dobservations at different depths. The reservoir as a whole presents a poor plankton structure with a density range of 12 to 320 UnitS/litre. 5 m and 10 m depths exhibited greater densities of-phytoplankton. Phytoplankton dominated 'at Dam site (Pump House) (80.9%), Pylon Colony (82.82%) and Nagarjunakonda Bay (59.8%) where algal strands developed along the margin, and on being dislodged from the submerged rocks/pebbles etc., entered the /plankton net. ~mile Myxophyceae (Microcystis) constituted the phytoplankton at Peddamonagal, Chlorophyceae (gedogonium, Ulothrix, Mougeotia, Spiro~yra) formed the major con8t~tuent at Pylon Colony, Pump House and Nagarjunasagar Bay. Diatoms, developing on the algal strands and submerged su~strata, comprised Pennales like Synedra, Fragillaria, Diatoma, Asterionella. Microcystis with Centrales like Melosira and gyclotella were observed tobe in abundance in Paddamonagal Bay where organic disintegration at the mucky bottom must have favoured their growth and multiplication. Among the zooplankters,Protozoa were observed to be poorly represented in the samples with comparatively greater numbers at Peddamonagal area largely comprising Ceratium. Cope pods consisted of Cycl?~, DiaptQmus and nauplii (40.0% in Peddamonagal -{()'f00.0% in Pump House and Eleswaram Bay). -8- . Daphnia and.:Diaphanosoma constituted the Cladocera which formed the important group next to Copepoda at Pylon Colony (35.3%), Nagarjunakonda (28<6%), ~IlidReservoir (20.0%) and Nagarj unakonda Bay (13.3%). Nlarch, being the summer montl: recording higher temperatures, should have favoured abundant growth of zooplankters. The overall zooplankton density ranged on the average betwefl 8 and 250 units per litre~ The following were the various planktonic genera observed during this i.nvestigation. PHYTOPLANKTON Wyxophyceae Oscillatoria Hicrocystis Bacillariophyceae Sinedra Tabellaria Pannales Navicula Fragillaria r, ,, , Diatoma , , Asterionella \ Cyclotella Centrales Melosira Chlorophyceae Ulothrix Mouge otia Spirogyra ZOOPLANKTON Protozoa Ceratium Rotifera Keratella Brachionus Copepoda Diaptomus Cyclop~ Cladocera Daphnia Diaphanosoma
Description:The list of books you might like
