Date of Award

1988

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Department

Oceanography

First Advisor

Candace A. Oviatt

Abstract

The food habits, metabolic rate and growth rate of juvenile scup (Stenotomus chrysops (L.)) in Narragansett Bay, R.I. were studied during the summer of 1987.

The instantaneous gastric evacuation rate of this demersal fish species was determined in the laboratory. The linear estimate of this rate was 0.17/hour and the exponential estimate was 0.34/hour.

Field studies were performed to determine the feeding periodicity of juvenile members of this species and the types of prey consumed. Scup were found to be daytime and therefore probably visual feeders. The types of prey consumed included polychaetes, mysids and other crustacea, molluscs, and fish eggs and larvae. Variation in the relative amounts of each prey type throughout a season indicated that this species is probably an opportunistic feeder.

The daily ration was determined by combining data from the gastric evacuation study with a 24 hour field study. Two estimates of daily ration were obtained depending on the type of evacuation model used. The linear estimate of daily ration was 3.99% dry weight and the exponential estimate was 3.49% dry weight. The benthic consumption rate of scup in Narragansett Bay was found to equal 0.6-1.7 g dry wt/m2 between June 1st and September 30th.

The metabolic rate of juvenile scup Stenotomus chrysops was measured in the laboratory. The average respiration rate (0.23 ml O2/g wet wt) of 46 of these one year old demersal fish was used to estimate their metabolic expenditure at 1.86% dry weight/day.

Two approaches were taken to estimate the growth rate of juvenile scup: a bioenergetic approach, and a length frequency approach. The bioenergetic approach, which used Winberg's energy budget equation, estimated growth at 0.93% dry weight/day. The length-frequency approach estimated the growth rate of juvenile scup at 0.84% dry weight/day during their summer residence in Narragansett Bay. The field estimate of the growth rate of scup agreed well with the bioenergetic estimate.

The growth rates determined in this study were used to calculate the body weight of scup that was produced in Narragansett Bay. This production was equivalent to 0.15-0.40 g dry wt/m2.

Share

COinS