New Zealand Journal of Marine and Freshwater Research abstracts

---

Aspects of the reproductive biology of torrentfish, Cheimarrichthys fosteri, in two braided rivers of Canterbury, New Zealand

G. J. SCRIMGEOUR¹*

G. A. ELDON²

¹Department of Zoology University of Canterbury Private Bag Christchurch, New Zealand

²Frcshwater Fisheries Centret Ministry of Agriculture and Fisheries P. O. Box 8324, Riccarton Christchurch, New Zealand

Abstract The reproductive biology of torrentfish, Cheimarrichthys fosteri Haast, was investigated in the braided Rakaia and Ashley Rivers, South Island, New Zealand. Fish matured in their second year (1+) with males exceeding 63 mm and females 65 mm in fork length (FL). Few fish lived for more than 3 years. Spawning is thought to take place in the lower reaches of rivers and occurred in both rivers from January to April. Gonosomatic index (GI) values for females were lowest from April to August, inclusive, in fish from both rivers; they peaked in October in the Rakaia and in January in the Ashley River. Male GI values were lowest during April-July and highest in October and March in the Rakaia and Ashley Rivers, respectively. Fecundity varied from 2769 to 55100 eggs and was linearly related to fish length. Juveniles (0+), 23-30 mm FL, entered the Rakaia lagoon primarily from April to September. Females dispersed up stream, up to 90 km from the sea, whereas males were most abundant in the lower reaches. The absence of juveniles in upstream localities suggests that early rearing is marine, and juveniles move up from the lower reaches of the river as they grow.

Keywords Cheimarrichthys fosteri; gonad maturation; sexual maturity; egg diameter; fecundity; fish migrations; braided river

New Zealand Journal of Marine and Freshwater Research, 1989, Vol. 23: 19-25 0028-8330/89/2301-0019$2.50/0 © Crown copyright 1989 Received 29 January 1988; accepted 4 March 1988

PDF file of entire paper: medium quality (511K); (scanned from paper original: notes about this process)

---

This year's abstracts | Journal home page | All abstracts | Publishing home page