Larval fish trophodynamic studies on Georges Bank: sampling strategy and initial results. In: The propagation of cod Gadus morhua L.: an international symposium, Arendal, 14 - 17 June 1983

Abstract

A sampling strategy is outlined to serve as a framework for determining the fine- to micro-scale vertical disribution or fish larvae and their prey on Georges Bank in a single vessel, interdisciplinary mode of operation. A major objective of this sampling program is to characterize the development and temporal-spatial variability of these distributions to evaluate growth and survival of larval populations. The operational plan, sampling gear and instrumentation, as well as special techniques employed are discussed in terms of the usefulness of the parameters measured. Initial results are presented from a two-part study conducted in April-May 1981, focused on haddock (Melanogrammus aeglefinus L.) and (Gadus morhua L.) larvae. In April, a gadid egg patch with recently-hatched larvae (C. 91% haddock) was located on the southeastern part of Georges Bank, between the tidally-well-mixed front (c. 60-m isobath) and the shelf/slope-water front (c. 100 m ). The water column along the southern flank was still well-mixed in April and the larvae were broadly distributed with a weighted mean depth between 30 and 40 m. Density of their dominant copepod prey was relatively low near the surface (<3 prey/1) but increased with depth (5-10 prey/1).