Analysis of Energy Flow and Production in an Unexploited Marine Flatfish Population

Abstract

The seasonal pattern of production processes in an unexploited resident population of American plaice (Hippoglossoides platessoides) in St. Margaret’s Bay, N.S., was analyzed with an energetics model which represents an extension of the analytical approach used in fishery theory. During summer, production is about twice the annual net production of 1.5 kcal/m² by fish aged 1 and up. The ecological efficiency is 17%, with larvae and 0+ fish accounting for some 20% of total population ingestion and 34% of net population production. Metabolic expenditures constitute the largest fraction (62%) of population energy intake and about 80% of this amount is consumed during summer. Plaice ingest about half the yearly estimated production (25 kcal/m²) of benthos in the deeper parts of the Bay.