Summer ichthyoplankton communities of two estuarine systems of Prince Edward Island

Abstract

Fish eggs and (or) larvae representing 22 species in 14 families were collected during the summer of 1983 at eight stations in the Hillsborough River estuary – Northumberland Strait area and three stations in the Tracadie Bay – Gulf of St. Lawrence region. Of the 62 287 eggs collected, 83.5% were either yellowtail flounder, Limanda ferruginea, or cunner, Tautogolabrus adspersus, and 5.9% were Atlantic mackerel, Scomber scombrus. The most abundant larvae were alewife, Alosa pseudoharengus, Atlantic mackerel, and cunner accounting for 24.6, 22.4, and 20.6%, respectively, of the total 5077 larvae and juveniles collected. The highest average concentration of eggs and larvae occurred in the coastal area near Tracadie Bay (4265 eggs/100 m3, 350 larvae/100 m3), in the Northumberland Strait region (2682 eggs/100 m3), and at the head of the Hillsborough River system (170 larvae/100 m3). The greatest species diversity occurred near Tracadie Bay (5.0 species of larval fish per tow) and in Tracadie Bay channel (4.0 species of larval fish, 6.0 species of eggs per tow). Summer variations in abundance and distribution were correlated with water temperature and salinity for the more abundant species (alewife, cunner, Atlantic mackerel, Gasterosteus aculeatus, Morone americana, Osmerus mordax, Menidia menidia, Pseudopleuronectes americanus). Species associations and station assemblages were analyzed using the Bray – Curtis dissimilarity measure and a numerical classification system.