Fish Population Dynamic and Stock Assessment (2+1)

Swept Area Method

This is a method, which is assumed as that the area swept by the trawl is representative for entire area over which the fishes are distributed.

Problem:

Calculate the total biomass, for 780nm² sq to the following readings recorded at a swept area survey in Gulf of Mannar area

Velocity of trawl net = 5 K not

Length of head rope trawl net = 50cm

Time taken / haul = 2 hrs

Velocity of current = 1 knot

Direction of vessel = 95^o

Direction of current = 85^o

Carangid catch in weight/haul = 60kg

Carangid catch in weight / hr = 28kgs

Fraction of head rope length (x²) = 0.5

Fraction of the biomass in the effective path swept by trawl (x₁) = 0.8