Effects of environmental factors on ichthyoplankton communities in the Miramichi estuary, Gulf of St Lawrence

Abstract

Ichthyoplankton in 20 taxa (17 identified to species, three to genus) representing 14 families were collected in 10 surveys of the Miramichi estuary between May and September 1992. The taxonomic composition was typical of other estuaries in the Gulf of St Lawrence and Gulf of Maine. Larvae of three anadromous species [rainbow smelt (Osmerus mordax), alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis)] were several orders of magnitude more abundant than any other taxon. The upper estuary (Miramichi River and its tributaries) probably serves as a nursery ground for larvae of these species and others such as Atlantic tomcod (Microgadus tomcod). The species composition of the lower estuary (Miramichi Bay) was dominated by typically marine forms and probably serves as a nursery ground for winter flounder (Pleuronectes americanus), smooth flounder (Pleuronectes putnami). sculpin (Myoxocephalus sp ) and sand lance (Ammodytes sp) Of the environmental factors investigated, salinity was the most useful predictor of larval distribution in the estuary.