Bioenergetics of a Sand Goby (Gobius minutus) Population

Abstract

This paper describes utilization of ingested energy by a population of sand gobies (Gobius minutus) in the Ythan estuary, Scotland, from November 1966 to March 1969. After metamorphosis (July) the gobies survived about 22 months, and their life could be divided into five stages: somatic growth (July–November); gonad growth (November–February); reproduction (February–June); more somatic growth (June–October); and further gonad growth (October–December). I calculated energy budgets for each stage from the relation:[Formula: see text]where: I = ingested calories; M = calories of metabolism; G = calories of growth.Since I had measures of ingestion, growth, and routine oxygen consumption, I hoped to predict active metabolism by the energy ingested not accounted for in growth and routine metabolism. In fact, 0.8I either equalled the sum of growth and routine metabolism or was much too little to explain predicted expenditures for these parameters. Analysis of published feeding and growth studies in fish indicated that energy imbalances of this sort at low rations are general and that fish seem able to shunt more energy into growth when on a restricted ration than one would predict from studies of standard oxygen consumption. This result together with earlier analyses of Paloheimo and Dickie (1966) indicate that energy budgets for natural populations not based on accurate natural ingestion rates are at best only crude approximations.