Recruitment and distribution of juvenile salmonids in Lake Coleridge, New Zealand

Rainbow trout (Oncorhynchus mykiss Richardson) and chinook salmon (O. tshaw ytscha Walbaum) fry and 0+ fingerlings entered Lake Coleridge, a deep, olig otrophic lake in the Southern Alps of New Zealand, in spring and early summ er and dispersed throughout the shallow littoral. In contrast, most juvenil e brown trout (Salmo trutta Linnaeus) remained in the tributaries for 1-2 y ears before migrating down stream to the lake. Juvenile salmonids (<350 mm) were more abundant in the shallow littoral(<10 m), especially near tributa ries, than in the deep littoral (10-40 m), or the surface layers (0-16 m) o f the limnetic zone which were populated by yearling (>150 mm) and adult sa lmon and rainbow trout (>210 mm). The abundance of 0+ rainbow trout in the littoral zone declined rapidly from February to August and stocks were supp lemented by a migration of yearling fish from the tributaries in spring. Th e shallow littoral zone and tributaries are both important for juvenile tro ut rearing in this lake.