N.Z. MARINE DEPARTMENT-FISHERIE,S BULLETIN No. .į

These rivers, in contrast with many waters in the South Island, prorrid. ,ro
evidence of having carried fish of a greater average size than they hàld to-day.
Records of captures from the wainui-o-mata indicate that, over a long periocl,
average size, despite s[rall fluctuations, has been well maintained. The three sets
of clata relating to the Hutt and its tributary, the Mangaroa, inclucle ma¡y small
satnples' Yet, separately and collectively, these sets of clata suggest that size has
been greater this century than it was about twenty years after the intrqduction of
trout' However, data frorn the Hutt itself relate to seasons beginning with 18BZ-8.
There is evidence of a very much greater average size of trout in 1885-6 ar-rcl
1886-7, the first two angling seasons. Then 130 trout, captured with unspecified
lures, hacl the liigh average weight of. 6.z6tb. The case is an extraorclinaiy or-,e,
becattse it is the only one of the }trorth Islancl rivers where a recluctiorl of size
is shown. Howevet, in 7945-6, some very good catches were nracle, inclucling o¡e
of twelve fish averaginc 5+1b., take' on *rinnow in the lower reaches. In the
Hutt, as in southern rivers, it would appear that angling is much influencecl
by sea-run fish, which in different seasons vary in qr"nlity "r,d size. The history
of the Hutt is discussed further in Appendix E.
In the Manawatu system, the size of fish in the principal strean and in the
oroua has been much the same in the rast fifteen yor, ". it was whe. a'gling
began, and, in so far as change is shown, it is favourable. The Makakahi ìow
shows an average size of .nearly clouble that eviclenced i' the 1g90's.
Lake Taupo is the only water where the local administrative authority has kept
records of size of fisli. Much of the rnaterial for the last two ancl a half decadès
was recorded by the Department of Internal Affairs.
The grouping of Taupo clata in decacles ter-rds to hide some remarkable changes
i' average size of rainbow trout. The fu[ clata show a' average weight of 6.51b.
in 1908-09, a rise to 8.5 lb. in 1910-1 1, a period of clepressecl-weighis of usually
between 3lb' and +.251b. frorn 1915 to 1920. a lairly sucl