Abundance, Distribution, and Diet of a Small-Bodied Ecotype of Windowpane

Abstract

Windowpanes Scophthalmus aquosus were collected during demersal trawl surveys in Northumberland Strait in the southern Gulf of St. Lawrence, Canada, during July and August 2001–2012. Abundance indices showed relatively little variation between years. Windowpanes were widely distributed in the strait, with 95% of the population occurring in water <23 m deep and with a temperature of >9.5°C. The Windowpanes collected were small, all <30 cm total length. Fish of all sizes fed mainly on sevenspine bay shrimp Crangon septemspinosa, followed by mysids and (for fish >20 cm) sand lances Ammodytes spp. and juvenile Atlantic Herring Harengus harengus. Small (<10-cm) individuals also ate crab megalops larvae. The mysids consumed on sandy–gravel substrates were Mysis spp.; those consumed on mud bottom were mainly Neomysis americana. Cannibalism was low, consisting of two individuals <1.6 cm.

Received May 23, 2013; accepted November 22, 2013

ACKNOWLEDGMENTS

This paper benefited from insightful criticism of earlier drafts by J. T. Kelly, A. J. Debertin, S. C. Courtenay, and two anonymous referees. Technical support was provided by I. Forest and D. Gagnon. Financial support was provided by the Fisheries Science Collaborative Program and Ecosystems Research Initiative Program of Fisheries and Oceans Canada.