Marine Fish Calendar. 10. Karwar

Karwar is situated almost at the northernmost (Lat. 14°50' N and Long. 74°03' E) tip of the Karnataka coast. It is the district headquarters of Uttar Kannada. The coastline extending from Majali in the north to Kasaragod in the south was once famous for rampart (shore seine) fishing till the advent of this decade. This part of the coast was called the 'mackerel coast'. The fishing in the Karwar area is based by and large on the purse seiners. As such the fish calendar is prepared on the fish landings of this gear only and the data covered is from 1981 through 1985

Estimation of mortality rates of the oil sardine, Sardinella longiceps Val.

The mortality rates of oil sardine, Sardinella longiceps from Karwar have been estimated based on the age composition of the fishery by adopting the method of Beverton and Holt. The values obtained are 2.43, 1.57, 3.70 and 2.96 for instantaneous total mortality and 0.98, 0.12, 2.25 and 1.51 for the fishing mortality durig 1965-66,1966-67, 1967-68 and 1968-69 seasons respectively. The natural mortality obtained in the final iteration process is 1.45. The estimation shows considerable changes from year to year ' inthe values of both total and fishing mortalities due to short-term changes in abundance offish

Studies on variations in the vertebral counts of Oil sardine along the north Kanara coast

The study on the sub-populations of the oil sardine Sardinclla longiceps Val. was made ibased on vertebral counts recorded from specimens collected at seven centres, Karwar, Binage, Shankrubag, Chendia, Bellekeri and Belambar situated over a stretch of about 40 km south along the North Kanara coast and Kankon at a distance of 35 km north of Karwar. In all, 68 samples comprising 2183 specimens in the size range 96-209 mm were examined during the period June 1973 - April 1975. The total number of vertebrae ranged from. 43 to 48, the mode teing at 47. It was found that vertebral variations were not significant in fiih below 160 mm length (mostly juveniles) and those above 160 mm (adults) suggesting that they were homogeneous in character. Data pooled from all centres showed significant difference indicating the possibility that samples drawn were from different sub-populations. Within centres, samples differed significally especially at Binage and Chendia suggesting that these belonged to difl'erent sub-populations. Samples from Karwar, Belambar and Kankon did not differ significantly. It is inferred that sub-populations exist in the oilsardine shoals striking the coast between Karwar, Belambar and Kankon

Occurrence of wahoo, oriental bonito and bigeye tuna off Karwar

The occurrence of the species Wahoo, Acanthocybium solandri,landed by purse siene, was observed ffirst time in the inshore waters of the west coast other than at Vizhinjam and Colachel situated at the extreme southwest coast of India showing a northern extenision of along the west coast.The pursesiene landing of Oriental bonito, Sarda orientalis and bigeye tuna, Thunnus obesus were also monitored and illustrated

Present status of oil sardine fishery at Karwar

The average annual yield of traditional gears (Rarnpan and Yendi) from 1937 through 1982 for 16 years is 146.4 t. Consequent to introduction of purse seiners from 1976, tf)e average catch for the 10 year period from 1976 through 1985 for oil sardine increased to 22^3 t at Karwar showing nearly 15.5 times more yield than the former period. This paper discusses whether this new development is a boon to the fishery or whether it has an adverse impact on the fishing stocks. For this purpose, the average standing crop and average annual stock of oil sardine in the fishing grounds for a year were estimated. An estimate on yield-per-recruit and the maximum sustainable yield (MSY) for varying fishing intensities and Instantaneous natural mortalities was made to understand the extent of fishing stress on the resource A closer scrutiny of all India catch data of oil sardine and mackerel from 1976 to 1980 when 35 to 400 numbers of purse seiners were introduced respectively, showed that the premechanisation period (1970-75) accounted for better annual average catch than the purse seine era (1976-1980) as the catch per day per purse seine declined. The optimum level of exploitation and the adverse effects on the stocks if they are indiscriminately exploited without proper planning are discussed in the paper

Hydrological conditions in the inshore Region of Karwar during 1965-1967

Studies on the hydrological conditions off Karwar were undertaken on board one of the vessels of I.N.P. during the years 1965 to 1967. The inshore samples collected from surface, 10 m and bottom (15-31 m), showed quite distinct demarlcation in the distribution of physico-chemical properties. The average monthly values of pH fluctuated between 8.0 and 8.4. Dissolved oxygen reached its maximum in the sub-surface layers. Saturation and supersaturation values were frequently observed at 10 m and 15-31 m than that at surface, indicating the zone of maximum photosynthesis below the surface waters. The distribution of nutrient salts showed that they are concentrated at bottom

A viviparous nematode, Philometra sp. In the ovaries of Otolithus argenteus (Cuvier)

While engaged in the study of spawning periodicity of certain teleostean fishes of Mangalore area, a parasitic nematode was observed in the ovary of Otolithus argenteus (Cuv.). The fish measuring 203 mm. in total length and harbouring the parasite within its gonads appeared to be normal in its external body features. The parasitised ovaries of the fish presented dark red colouration and through the semitransparent ovarian walls some of the coils of the parasite within could be seen. Except in the anterior one-third of the left ovary and the apical region of the right one where a few ovarian immature eggs measuring 0.019 to 0.134 mm. were found, the rest of the space in both the ovaries was occupied by the coils of the parasite. When the coils were unravelled, it was observed that in the region of the oviduct the part of the body of the parasite lying within the left ovary was continuous with that lying in the right ovary

Estimates of yield-per-recruit and stocks of lesser sardines Sardinella gibbosa (Bleeker) and S. dayi Regan, in the Karwar waters, West Coast of India

Consequent to the introduction of purse seiners in the Karwar waters, lesser sardine catches showed improvement forming 4-5 % of total marine fish production. Along with major pelagic fish resources of oil sardine and mackerel, this group also supports fishermen of this region economically. To understand the extent of fishing stress on the lesser sardine resources viz. S. gibbosa and S. dayi, studies on yield-per-recruit (Y/R) and the maximum sustainable yield (MSY) for five years 1979 through 1983 were made. The MSY levels for both the species mentioned above will be reached at 1.0 F and 1.8 F respectively. The standing stocks and the potential average annual yields in the fishing grounds for both the species were also estimated and details are presented in this paper

On the maturity of Sardinella dayi Regan in Karwar Region (West coast of India)

Study on spawning biology of Sardinella dayi Regan for 1979-83 period shows that the size at first maturity is attained around 140 mm. For determining maturity and nature of spawning, condition factor (K) and gonadosomatic index (GSI) were utilized. The spawning in this species is protracted and lasts from October - December, and from January - May on a reduced scale. Relation of fecundity to length and fecundity to weight when tested statistically showed better correlation in 1979 and 1980, than in the rest of the years and the analysis of variance showed different rates of egg production during different years. Studies on fecundity showed that generally 66,000 eggs are released by each individual in the spawning act

Maturation of the intra-ovarian eggs and the spawning periodicities in few fishes of Mangalore area based on ova-diameter measurements

Ova-diameter studies have become an integral part of fishery biological research. It is well known that in most fishes there is a marked seasonal periodicity in egg production. Clark (1934) and Hickling and Rutenberg (1936) have shown that it is possible to determine the time of spawning and the spawning periodicity of fishes by ova-diameter frequency studies. Karandikar and Palekar (1950, 1952 and 1953), Prabhu (1956), Dharmamba (1959) and Karekar and Bal, (i960) among others have shown that this method is applicable in regard to the fishes they studied. This account deals with the determination of the time and periodicity of spawning of four common food fishes of the South Canara coast viz., Nematalosa nasus, Anodontostoma chacunda (Family Clupeida.e); Otolitkus argenteus (Family Sciaenidae), and Saurida tumbil (Family Scopelidae), based on the frequency distribution of the diameter of the intraovarian eggs