Fish Population Dynamic and Stock Assessment (2+1)

Collection and processing of Length Frequency Data.

(i) Samples for length frequency should be collected at random from the commercial catches as soon as they are landed. Sampling should be done before sorting into various market size groups.

(ii) Length data should be collected separately for different gears and for different mesh types of the same gear.

(iii) Length frequency data are to be recorded twice or thrice in a week from the landing centre.

(iv) While collecting the length data, sexes should be treated separately.

(v) Which recording the length data, total length or fork length or standard length should be taken depending on convenience. The data should be recorded in mm or cm in a primary register.

(vi) It is better to take the length frequency data for a minimum period of two years (24 months).

(vii) Classify the individual length recorded into length groups which should not normally exceed twenty five.

(viii) The weekly data may be pooled on a monthly basis

(ix) The data thus pooled must be drawn in the favour of frequency polygons or histograms for each month.

(x) Trace the progression of the modes through successive months