New Zealand Journal of Marine and Freshwater Research abstracts

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Age and growth of alpine galaxias (Galaxias paucispondylus Stokell) and longjawed galaxias (G. prognathus Stokell) in the Rangitata River, New Zealand

MARTIN L.BONNETT

Freshwater Fisheries Centre Ministry of Agriculture and Fisheries P.O. Box 8324, Riccarton Christchurch, New Zealand

Abstract The age and growth of alpine galaxias (Galaxias paucispondylus) and longjawed galaxias (G. prognathus) were determined from samples of fish collected from the Rangitata River, Canterbury, New Zealand. Both species are small (total length up to 112 mm and 87 mm respectively), slender fish with entirely freshwater life histories. Aged from sagittal otoliths, the majority of fish were age 0⁺ and age 1⁺, although alpine galaxias up to age 4* and longjawed galaxias up to age 3+ were found. Growth of both species was greatest during their first year of life. Alpine galaxias continued to grow in subsequent years, but fish of ages 2⁺, 3⁺, and4⁺ were exclusively females. Longjawed galaxias showed little increase in length after their first year of growth, but for all ages > 0⁺ the females were significantly larger than males. Overall, both species are not only similar to each other, but also similar to the dwarf galaxias (G. divergens) and the common river galaxias (G. vulgaris), particularly in terms of their size, habitat, diet, and the age structure of populations.

Keywords alpine galaxias; Galaxias paucispondylus; longjawed galaxias; G. prognathus', age; growth; freshwater fish; otoliths; Rangitata River

New Zealand Journal of Marine and Freshwater Research, 1990, Vol. 24:151-158 ; Gown copyright 1990
Received 11 October 1989; accepted 24 January 1990

PDF file of entire paper: medium quality (1047K); (scanned from paper original: notes about this process)

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