The Distribution of Chaetognatha in the Gulf of Alaska in 1954 and 1956

Abstract

Zooplankton collections from two cruises to the Gulf of Alaska during 1954 and 1956 were studied to determine the species of Chaetognatha present, to establish their distribution within those waters, and to consider the distribution of the species with regard to certain general hydrographic features prevalent in the region at the time the collections were made. Also considered were a few collections made during the summer of 1958 in the waters surrounding San Juan Island in the San Juan Archipelago, Washington.The general oceanographic features of the Gulf of Alaska are described. The distributions and frequency of occurrence of 3 species of 2 genera of chaetognatha are described and discussed. Eukrohnia hamata is found at most off-shore stations, diminishing in number nearer the coast in less saline waters. Sagitta elegans is apparently cosmopolitan in the areas studied. S. lyra an oceanic form, was found in regions influenced by waters of the Subarctic Region and the American Coastal Region. The presence of S. lyra in inland waters of the San Juan Archipelago during the summer of 1958 is considered to be an indication of the shoreward movement of oceanic waters.