Triploid Browns and Native Trout

Fish biology tells us that streams have specific holding capacity. Won't these trips' still displace the natives ?
from the pages at Fish Farmer magazine
22 April, 2008 -

PROTECTING native brown trout is at the heart of a new Environment Agency approach that it says will benefit both anglers and the native trout population in rivers and lakes throughout England and Wales.
Angling is one of the most popular outdoor pursuits, bringing many social and economic benefits. Every year, fishery owners and clubs introduce almost 700,000 fertile farmed trout into rivers and lakes to supplement stocks for anglers.
Under the new policy, infertile triploid brown trout will be used to stock these waters in a move to protect wild trout (including sea trout) stocks. The Environment Agency will stop giving consent to stock fertile farmed brown trout into rivers and most lakes in England and Wales from 2015. Targets have been set to encourage fishery managers to progressively switch to the use of infertile triploid fish to supplement trout stocks in these waters.