Some aspects of the biology of 'Ghol' Pseudosciaena diacanthus (Lacepede)

Sciaenids popularly called 'croakers', 'Drums', 'Jewfish', and 'Whitings', contribute; substantially to the fisheries of India. Sciaenids form about 6% of the total annual marine fish catch of the country. About 30% of the landings of the trawlers at Bombay is composed of Sciaenids. Pseudosciaena diacanthus (ghol), Otolithoides brunneus (Koth), Otolithus ruber, Otolithus argenteus, Pseudosciaena sina, Johnius dussumieri are the important species contributing to the sciaenid fishery besides other species of lesser importance. Smaller sciaenids, mostly Johnius spp., and Otolithus spp., locally called 'Dhoma' constitute the bulk of the catches of the trawlers (20-23%) ** Bombay. Pseudosciaena diacanthus locally called 'ghol', ranks first as a commercially very important offshore sciaenid, forming 5 to 8% of the trawler catches

Length-weight relationship in Saurida tumbil and S. undosquamis and relative condition in s. tumbil

Length-weight relationship in Saurida tumbil and S. undosquamis and relative condition in s. tumbi

Maturation and spawning of lizard fishes (Saurida spp.) From northwestern part of Bay of Bengal

Ova-diameter frequencies indicate that the spawning period in 5. tumbil is protracted, extending from October to Marcti, with the peak in November- December and that the eggs are shed in 5 or 6 batches. The minimum size at first maturity and size at 50% maturity in female have found to be 260 and 300 nun in total length, respectively. The fecundity estimates ranged from 37,569 to 2,14,981 eggs in the size range 290-430 mm. Ova counts per gram of the ovary were calculated for estimating the number of eggs spawned in different batches. A plot of fecundity values against length showed an exponential relationship of the form, F = AL while the relationship between the fecundity and weight of fish is expressed by a linear regression equation of the form Y = A + BX. The available data indicates that the spawning and maturation in S. undosquamis may be similiar to that of S. tumbil The differences between specimens of S. tumbil. from Waltair, Mangalore and the East China and Yellow seas in respect of the size of the ova, spawning period and other characters are given

Estimates of mortality and yield per recruit of 'ghol' Pseudosciaena diacanthus (Lacepede)

The mortality rate and yield per recruit of 'ghol, Pseudosciaena diacanthus, are estimated from the age composition of catches of the bull-trawlers of the New India Fisheries Ltd., Bombay, for the years 1958 to 1961. The annual mortality rate estimated from (1) catch per unit effort data and (2) the average catch curve of 1958-'61 lies roughly between 0.55 and 0.60 and the instantaneous mortality rate between 0.83 and 0.87. Since the fishery for 'ghol' was at the beginning stage with only two pairs of bull-trawlers operating commercially, the estimated total mortality rate (Z=0.83) is regarded as practically equal to natural mortality rate (M). The yield per recruit Yw/R for various lex els of fishing mortality (F) were calculated with M=0.83 and the maximum value of Yw/R was found at a value of F=0.6, which shows that the catch from the stock can be stepped up considerably over the present level. Before deciding to step up the catches of 'ghol' by expanding the trawl fishery, it is necessary to have estimates of fishing mortality generated by the.'dol' nets and gill nets on this fish

Studies on the age determination of 'Ghol',Pseudosciaena diacanthus (Lacepede)by means of scales and otoliths

The fact that tropical fishes also show periodical growth checks (rings) on their discrete hard parts has been demonstrated in a few Indian species (Nair, 1949; Seshappa and Bhimachar, 1951, 1954, 1955; Pillai, 1954; Radhakrishnan,1954, 1957; Sarojini, 1957; Jhingran, 1957; Seshappa, 1958 and Balan, 1959). Work on the biology and fishery of Pseudosciaena diacanthus occurring in the waters off Maharashtra and Gujarat coasts was started by the present author in March, 1958 and during the course of two years study, it has been found that the scales and otoliths of this species show growth checks (rings) which can be utilised for the determination of age and growth as was indicated by Seshappa (1953)

Age and growth of 'Ghol', Pseudosciaena diacanthus (Lacepede) in Bombay and Saurashtra waters

n an earlier paper the present author (Rao, 1961) had shown that the scales and otoliths of 'Ghol', Pseudosciaena diacanthus (Lacepede), a commercially important sciaenid in Bombay and Saurashtra waters, are useful as age indicators of this species. The results of studies on the growth of this fish based on these structures and the length frequency data for the period 1958-62 are presented here. Further, von Bertalanffy growth equation was fitted to the length-at-age data and estimates of the parameters were obtained and compared with similar estimates of other sciaenids from different regions

Studies on the populations of Saurida tumbil (Block) From Indian waters

A. comparison of morphometric and meristic characters of S. tumbil respectively by means of analysis of covariance and analysis of variance indicated that there may be three populations of iS. tumbil in Indian waters, coniined to (1) Visakhapatnam-Kakinada, (2) Bombay-Mangalore, and (3) Tuticorin

Food and feeding of lizard fishes (Saurida spp.) From north western part of Bay of Bengal

The food and feeding of Saurida turnbil was studied with reference to size of fish, time (seasonal and diurnal), regions (latitude zones), sex and maturity. Though there was not much difference in the composition of the food in respect of the above factors, variations were however, 6bserved in the intensity of feeding. Fish formed the single major component <70 to 80%) of the food. The feeding intensity was low during the spawning period. Two peaks, one in the morning and the other in the noon, were observed in the feeding intensities according to time of day. The maturing fish bad the highest feeding intensity. The values of Ivlev's index of electivity (E) for Letognathus blttdus were positive for 6 months and negative for 4 months. The results1 of studiesi on the food and feeding of S. undosquomis and S. longimarms are more or less similar

Age and growth of lizardfishes (Saurida spp.) From The northwestern Bay of Bengal

Legnth-frequency study shows that 5. tumbil may grow to 170/190, 270/ 290, 350/370 and 410/430 mm respectively at the end of 1st, 2nd, 3rd and 4th year. These growth rates are similar to those estimated for fish in the East China and Yellow seas, where it is known to attain a size of 550-560 mm in 5 to 6 years, the maximum size recorded there being 636 mm (fork length). Specimens above 450 mm were, however, not observed in the trawl catches from the Bay of Bengal. Von Bertalanffy equation for growth in length was fitted for length-at-age data of S. tumbil and the values of various parameters were estimated as K = 0.249; t, = -0.334; L a = 637 mm. S. iindosquamis may attain a size of 170/190 and 270/290 mm at the end of 1st and 2nd year, respectively. Specimens above 340 mm were not recorded, and the life span in this species therefore may be 3 years

Exploratory trawling on the continental shelf along the north-western part of the Bay of Bengal

The results of exploratory trawl'ng undertaken from 1961 to 1965 on the continental shelf along the north-western part of the Bay of Bengal, between latitudes 16''40'N and 2rOO'N are presented. The composition of the catch, the distribution of the various categories of fishes and their relative abundance in space and time are indicated. It is estimated that in commercial fishing, with Visakhapatnam as the base, a 25 m side-trawler with 15 m trawl should be able to land 250-390 metric tons of fishes, a 14 m stern-trawler with 14m trawl, 67-174 metric tons, and a 13-7 m stern-trawler with 12 m trawl, 56-94 metric tons per year from the area