Galaxias maculatus dominated the whitebait catch in 11 of the 12 Bay of Plenty rivers studied. In four rivers, this species accounted for 84-99% of the catch. However, in seven other rivers, G. maculatus accounted for only 52-70% of the catch, and major (>18%) contributions were made by either Galaxias brevipinnis or Galaxias fasciatus. hi the twelfth river, the Motu River, G. brevipinnis dominated the catch, accounting for over 70% of whitebait caught. This is the first report of a rivermouth whitebait fishery dominated by G. brevipinnis. Rivers where G. brevipinnis contributed more than 18% of the catch were all within a 70 km radius west of the Motu River mouth. In rivers beyond this limit, G. brevipinnis was less than 2% of the catch. Such differences in species composition may result from river-mouth selection by migratory juveniles of G. brevipinnis.
Temperature avoidance behaviour of inanga, Galaxias maculatus, was studied in the laboratory using a two-choice tank. The final preferred temperature of inanga is about 20°C but fish acclimatised to cooler temperatures (15 and 17°Q prefer warmer waters (up to 23 and 26°C, respectively). Fish acclimatised to temperatures of 15,17, and 20°C showed total avoidance at 29.5,31, and 31.5°C, respectively. Water temperature therefore is an important factor influencing upstream migration and distribution of inanga and thermal discharges can be disruptive.
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