Estimation of accidental gaps in the data on Sample survey of marine fish landings

In sample surveys carried out to estimate the monthly marine fish landings, instances often arise when the relevant data in parts are lacking. A statistical method for the estimation of such gaps has been developed which seems to meet the requirement within limits

Problem of nonadditivity in two-way analysis of variance of data for comparing the efficiency of fishing gears

To bring out the relative efficiency of various types of fishing gears, in the analysis of catch data, a combination of Tukey's test, consequent transformation and graphical analysis for outlier elimination has been introduced, which can be advantageously used for applying ANOVA techniques, Application of these procedures to actual sets of data showed that nonadditivity in the data was caused by either the presence of outliers, or the absence of a suitable transformation or both

Quantitative ecology of phytoplankton in the Cochin backwater

A one-year study on the standing crop in terms of chlorophylls, primary production and total-cell counts of four station grids has shown that there were regional and seasonal variations in the magnitude of phytoplankton production in the Cochin backwater. Statistically treated using a microcomputor, a multiple regression relationship has been established between parameters within stations. But th<^ Correlation coefBclent and Standard Regression coefficient have revealed that the plankton production and the related parameters at all the stations were independent of each other and the parameters varied from station to station. Probable reasons are briefly discussed

Plankton production in the Vembanad Lake and adjacent waters in relation to the environmental parameters

The Vembanad Lake and its connected backwater system around Cochin are well known as the nursery grounds for the commercially important fishery resources of this area. This account embodies the results of studies on the environmental parameters of the estuarine system around Cocb in extending over an area of 300 sq. km. Observations were made on the hydrography, primary and secondary productions. The relative influence of the environmental factors like, temperature, salinity, dissolved oxygen and nutrients on the plankton production is interpreted from the correlation coefficient

Bombay duck (Harpodon nehereus) fishery During 1950-72

The Bombayduck catch forms about 7% of the total, all' India landings. 97% of the catches of this fish comes from tbs coast of Maharashtra and Gujarat. Difference is observed in the pattern of seasonal variations along the Maharashtra and Gujarat coasts though the peak and trough periods for the two states coincide. The annual landings varied between 7 and 128 thousand tonnes during the 1950- ,72 period. After 1959 the bulk of the fishery appears to have shifted from Maharashtra to the Gujarat coast. During the 1960-72 period, it was the Gujarat catch that determined the trends in the landings of this fish for the country as a whole

Exploratory survey along the south-west coast of India with reference to the use of try-net

The results of an exploratory survey for the assessment of prawn resources conducted along the south-west coast of India for a short period in 1967 are presented. The trend in total catch as well as prawn catch showed a decrease from the beginning to the end of the survey. During the survey, besides two trawl nets, a small try-net was aslo used for testing the grounds. A non-parametric test was applied to the catches by the two types of nets, the trawl net and the try-net, and it was found that the catch efficiency of the nets was the same. The possibility of using such a try-net for exploratory surveys and also for testing the grounds during commercial trawling is discussed

Length weight relationship in the threadfin-bream, Nemipterus japonicus along the Kerala coast

The length-weight relationship in N. japonicus of the Kerala coast shows no change in the form of the relationship when classified according to maturity and sex. The t-test shows that the cubic law does not hold good for this species. Instances of more than one value of weight for a given value of length are found more frequently in females than in males. A comparison of the relationships for the Andhra-Orissa coasts with those of the Kerala coast gives some differences which probably signify that separate stocks may exist in the Bay of Bengal and the Arabian Sea

The fishery of the oil sardine (Sardinella longiceps) during the past 22 years

The annual landings of the oil sardine, Sardiriella longiceps, in India, for the past 22 years are presented. The trends in the landings and the factors responsible for the fluctuations are discussed. The landings along the Kerala coast are found to determine the trends in the all India landings of this fish

Studies on the phytoplankton of the Cochin backwater A tropical estuary

The paper deals with the seasonal and spatial variation of phytoplankton, based on the observations at four stations (Aroor to Fairway Buoy) in the Cochin backwater during 1972-73. Two peaks of phytoplankton abundance are usually observed, with the diatoms playing the major role in determining the pattern of seasonal variations. An analysis of variance indicates that the spatial variation is as high as the seasonal variation. The usefulness of chlorophyll a in relation to the phytoplankton counts as a measure of the phytoplankton abundance has been studied by using the correlation coefficients; it has been found from an analysis of covariance that a common relationship exists between phytoplankton and chlorophyll a for the estuary. The fluctuations in some of the environmental characteristics have been discussed with their relative influence on thei production of phytoplankton. In the light of the results obtained, outlines of modifications in the sampling procedure have been given to the study of phytoplankton production in the estuary more comprehensive