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

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