Pelagic fisheries

Fishery statistics for the year 1976 give the total landings of pelagic species from the English Channel as approximately 146 000 tonnes wet weight, i.e. 146 X 109 g wet wt. Taking the area of the English Channel as about 82 X 109 m2, this catch of pelagic fish amounts to 146/82 = 1.8 g wet wt-m-2-yr-1. Assuming the wet weight of fish to be six times the dry weight, pelagic fishing therefore took 0.3 g dry wt-m-2-yr-1. If the calorific value of the fish is 5.0 kcal-g-1 dry wt, the energy content of the catch was

for the whole of the English Channel.

According to our previous calculation, tertiary production amounts to about 3.4 g dry wt, so in 1976 pelagic fishing cropped about 0.3 X 100/3.4 = 8.8 per cent of production at this trophic level.

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