The oil sardine fishery has contributed in no

small measure to the economy of the

fisherfolk of the West .Coast of India, and apart

from its food value, the fish has sustained prosperous

oil and guano industries for well over

a century. ' The fishery, however, is subject tn

extreme fluctuations and its continuous failure

during the forEes extending over several years

had disastrous consequences on the fishing

industry

Nair, R V

Subrahmanyan, R

CMFRI Digital Repository

No.2] Feb. i955 4i. THE . DIATOM, FRAGILARIA OCEANICA CLEVE, AN INDICATOR ABU NDANCE OF THE INDIAN OIL SARDINE, SARDINELLA LONGICEPS CUV. AND VAL.' OF R. YELAPPAN NAIR AND R. SUBRAHMANYAN Centra~ Marine Fisheries Research Sub~Station, Kozhikode THE oil sardine fishery has contributed in r·D small rn,easure to the economy of the fisherfolk of the West .Coast of India, and apart f rom its food va lue, the fish has sustained pros-perous oil and guano industries for well over a century. ' The fishery, however, is subject tn extreme fluctuations and its continuous failure during the forEes extending over several year s had disastrous consequences on the fishing industry. Factors governing these fluctuations have been the subject of investiga tions for over th ree decades. Since the inception DC the Marine Fishceies Research Station of the Government of India, sardine investigations have been actively pur-sued at the SUb-Station at Kozhikode, which was set up in 1948. Intensive studies on the biology and fishery of the oil sardine and related subjects have been in pro-gress with the primary object of determining the causes responsible for the fluctuations ell·' countered in the fishery. One of the aspects of study related to the food and feed ing habit; of the different age groups of the oil sardin€ with special reference to the seasonal changes in the composition of its food , both in quan-tity and quality. Even dllring the early phase of this jnvestigation, it became apparent that the oil sardine .is a plankton feeder showing a special preference for phytoplankton, with the diatom FragiLaria oceanica forming a major constituent of its food. Further studies have re-vealed that FTagilaria oceanica constitutes the main component of the food of the juveniles which form the mainstay and bulk of the com-mercial fishery and also, occasionally, of the adult oil sardine.:! From the accounts so far publishec, it would appear that blooms of Fragilaria. oceanica. in the Indian waters are confined to the Laccadive Sea. This 'diatom is absent in other places, or if present, it occurs only in such small numbers as to be easily overlooked. Very rarely, a few numbers have been encoun-tered 'on the Madras Coast.::: It is interesting to note in this connection that large-s cC:l.le shoaling of the oil sardine is confined to thi::-* P ublished with lhe permission of th e Chif:f Research Officer, Central Marine Fi ~heries Research St~tion, l\-Iandapam Cam I)' _. 4 region of the West Coast where the diatom also occurs in abundance. Intensive studies on the qualitative ::md quantitative aspects of phytoplankton produc-tion and of the major constituents of the IJlarine flora have been in progress simultaneously ar.d these have ~ho\Vn that phytoplankton pro-duction attains its peak during the South-Wc3t monsoon months (June-September) and one of the major, if not the foremost, constituents of the peak is Fragila.ria oceanica. This diatom, which forms flat, ribbon- like colonies, gene-rally attains the height of its developmf:!nt between June and October, the intensity of its development fluctuating to some extent frOI11 time to time. Continuous observations over a period of seven years have indica ted that the diatom has an asexual vegetative phase in its life-cycle lasting from three to four years, after which it forms auxospores, presumably by a sexual process; this process rejuvenates the protoplast and lal'ge new cells are formed which multiply by repeated vegetative divisions. The presence of considerable numbers of chains composed of large cells at three to foul' year intervals permits this interpretation. It is well known that in diatoms, immediately after auxcspore-formation, the rate of vegetative multiplication is rather fast and that this rat>:; slows down gradually as the cells undergo i.·e-pea ted divisions until auxospol'e -formation again provides the necessary stimulus for re-newed activity.-l ,::; Thus, ·in the present in-stance also, every four years or so, the Fragi-laria bloom is more ir.tense than during the in-between years. During the period of investi -gation in the pl'esent area two such bloom .. , one in 1949 and the other in 1953, were ob-served. These fluc tuations in the bloom of Fragilaria, and thus its availability, seem b show an interesting relationship with those of the oil sardine fishery. The oil sardine fishery commences along the West Coast with the onset of the South-West monsoon and the stock at this time is com-posed of active spawners.:! These disappear with the· cessation of the monsoon and the juveniles enter the fishing grounds i~ enol'.mous shoals to contribute 10 the bulk Qf the • F. oceanica Cleve, an Indicator of Abunda:nce of s. LC1zgiceps ;. J._C~("rent . '·_' l ,Scrence .. ~. - .. " -' . commercial lan<iings dur ing: the .peak period of .. the.' recovery. ,of .th~ .oil sardine .1isl}ery.·· \J{hicJ.l the fishery. As poin ~ed out by Panikkar,G all was a contiI)uous failure for several preceding previous workers are unanimous in ascribing the years. - This progressive ' recovery of the fishery ~uccess of the oil sardine fishery to the abund- culminated in the exceptionally good 1953-54 anee -of the " juveniles only. It is significant that season, which coincided . with- the 'second out-the. peak of the oil sardine fishery, when th~ standing bloom of FragiLaria in 1953, when the juvehiles dominate the catches, is reached heavy landings composed of juveniles contri-during or immediately after the peak: of Frag'i- buted to one of the most sc.ccessful laria oceanica. Further, a secondary maximum fisheries during _ the last ·qua;:ter of a cen-in the bloom of this diatom has also been ob- tury. It may be pOinted out that the next out-served during certain years accompanL~d by standing bloom of Fragilaria oceanica is ex-heavy landings of juvenile sardines. The in- pected in 1956-57 and this surmise together fiuence of this diatom on the oil sardine wa.; with the expected good recruitment consequent markedly noticed during the 1951-52 season on the abundance of the spawners in the fish-when the fishery which was steady till octo- ery of the current season, i .e., 1954-55, indl:ates ber 1951, suffered a severe setback during the a good oil sardine fishery during that season, subsequent months owing to the scarcity of provided the hydrological and other fac tors are also favourable. Fragilaria in the fishing grounds. The fishC'ry Our thanks are due to Dr. N. Kesava Panik- . revived with the reappearance of the diatom kar for his keen interest and valuable sug-by the end of December 1951. These investigations on the oil sardine and Fragilaria oceanica extending over seven years lead to the inescapable conclusion that one of the major factors governing the fluctuations of the oil sardine is the availability of Fragila·rill oceanica which is its favourite food. 2 It was mentioned above that during the last seven years Fragilaria attained two outstanding peaks in the years 1949 and ]953 caused by the rejuve-nation process in its life-history. It would appear that the bloom of 1949 may have he~ped gestions. 1. Nair, R. V. and Chidamharam , K., "A review of the ]ndian oil sarrHr.e fishery," Proc. Nat. but. Sd., hidia. 1951, 17. 71. 2. Nair, R. V. , Proc. htdo·Pacific Fish. Coun., 1953, 1]5. 3. Subrahmanyan , R., PrIX. Ind. Acad. Sci., 1046 , 24.85. 4. Iyengar. M. O. P. and Subrahmanyan, R., J. Ind. B ot. S(lc., 1944,23. 125. 5. Suhrahmanyan. R., /11. O. P. lyl!1lg'ar Comlll. Vol.: j. hid. Bot. Soc .• H146, 239. 6. PaniHar, N. K ., "H~herie:> Research in I ndia, Part I," J. Rom. Nat . His!. Soc., 1952, SO, 741. CONQUEST OF SOLAR ENERGY T:1E harnessing. of huge amounts of energy now going to waste in the desert and arid areas of the earth was the topic of a sym-posium held recently at New Delhi under the joint auspices of UNESCO and the National Institute of Sciences of India. One of the most striking papers "\ p:-esented ,vas -that of Professor V. A. Baum, Head of the Helioiechnical Laboratory at the G. M. ~zhizhanovsky Power Institute at Tashkent in the Soviet Union. 'With nearly a million square miles of arid lands, the use of solar energy is being treated as a major problem in the -U.S.S.R. In Tashkent, every square metre of land re-ceives more than a million ·kilocalories of sun energy per year, and the Soviet : SCIen-tiSts : have succeeded in developing paraboloid teflectors ten metres in diameter which produce i OO lb. of steam per hour at a pressure of 100-lb. per ~quare. inch. Such heaters have been used for the operation of canneries, for distilling water, operating refrigerators, and for heating the laboratory. In another applicaaon, solar heaters have been developed to make fresh ' water from salt. A practical still of this type . has been used to make 75,000 tons of distil1ed water and 12,000 tons of ice a year. The U.S.S.R. s tate Optical Institute has con-!'tructed a number of solar kitchens using alu-minium mirrors 4 feet in diameter which can produce 6 quarts of boiled water per hour. Work is now continuing to develop a ~olar steam generator which can be used as a heating plant in winter and a cooling p'ant in summer for cinemas, hospitals and house.;;. The deveiop~ ment of ic~-making ._and of air-coridifiotling is considered especially important in tho~ arid regions where the suffering of t he pm)·ul~tio.n. from heat ln summer· i:! as severe as that. fr cilTI ('old in ' the winter. . -.. ,--~,-.. ", .. 

The diatom, Fragilaria oceanica Cleve, an indicator of abundance of the Indian oil sardine, Sardinella longiceps Cuv. and Val.

Velappan Nair, R.

Subrahmanyan, R.

Publications of the IAS Fellows

The diatom, Fragilaria oceanica cleve, an indicator of abundance of the Indian oil sardine, Sardinella longiceps cuv. and val.

http://repository.ias.ac.in/36532/1/36532.pdf

The diatom, Fragilaria oceanica Cleve, an indicator of abundance of the Indian oil sardine, Sardinella longiceps Cuv. and Val.

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