Home range and movements of the common river galaxies, Galaxias vulgaris Stokell (Pisces: Salmoniformes), in the Glentui River, New Zealand

Abstract

Two-hundred and twenty-nine post-juvenile G. vulgaris from the Glentui River were marked with Alcian Blue dye administered to various fin combinations with a jet inoculator in March and April 1971, and their distribution examined by electric fishing at intervals until February 1972. After each survey all fish were returned to the river. Of 384 recaptures, 97 % were taken within the sections of the river in which they were marked (length range of sections 24-68 m) or within 200 m of them, and only seven fish were recaptured in areas other than riffles, the normal adult habitat. Fish moved upstream to suitable spawning areas in July and August, but returned after spawning. A change in habitat from riffle to pool, caused by the build-up of water behind a fallen tree, resulted in fish modifying their home range by moving to adjacent riffles. Field and stream-tank observations suggested that newly hatched fish are swept downstream to quiet stretches, and stream-tank studies indicated that juveniles move back upstream to riffles.