Document Type

Article

Publication Date

1981

Keywords

trophodynamics, marine biology, plankton, zooplankton, tropical-subtropical

Abstract

The adult and juvenile life stages of the small (~25mm) zooplanktivorous mesopelagic fish Valenciennellus tripunctulatus (Esmark) are found at depths of 200-600m throughout the diel period. Average population density was estimated to be 5 fish (104m3)-1 and the maximum density recorded was 11 fish (104m3)-1. Copepods constituted ~95% of all food items identified and Pleuromamma was the principal forage genus, contributing 31% and 56% to numbers and biomass of food items, respectively. Ontogenetic changes in diet were observed, the percentage of larger copepods increasing in the diet with increasing fish size. Food items were primarily 1-4mm in size. The relationship between number of prey in stomachs and fish length was not statistically significant whereas prey biomass was highly correlated with fish size. A diurnal feeding pattern was apparent, the period of most active feeding being 1200-2200 h. Daily ration, as estimated with regression equations, varied with fish size and increased more slowly in relation to standard length than to fish biomass. Maximum estimated daily ration as a percentage of body weight was 5.6% for 15mm fish and 3.7% for 30mm individuals. The average number of prey items in fishes taken during the period of active feeding was 9 while maxima varied between 14 and 24.

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

Marine Ecology - Progress Series, v. 5, no. 1, p. 1-10.

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