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

S-inch fingerlings can be pr:oducecl at betrveen four ancl eight titires the cost of fry.
In Canada Nîottley (1935') fotrnd that when fry were being handled in large
quantities they could be produced for about .$1.75 per 1,000. The cost of 123,000
brown trout fingerlings of 3 inches was about $24.00 per 1,000. This amount
includes tl-re cost of the 170,000 fry required to give a survival of 123,000 fingerlings,
the cost of foocl, wages and one-tenth of the cost of ponds required to holcl
tlie fish. These fingerlings, at thre:e months, cost 13 or 14 times as much as fry.
That is to say, it cost 13 or 14 tirnes as much to produce fingerlings rvhich at an
or-rtside estimation could not have had more than eight times the survival expectancy
of fry. As Mottley's costing is for 3-inch fingerlir-igs elrcl the survival expectancv is
taken from experiments with fish of 3 to 5 inches, it seerns safe to assert that a
better return to-the angler rvould be obtained by buying fry than the much smallelntrmber
of fingerlings rvtrich could be produced for the salne sll1l.
This conclusion is in keeping r,r,ith that of l{eedharn and Sutlrner (1941) for'
brook trout of difierent sizes leleasiecl into lakes at clifferent seaso11s. Small marked
fish of 2 inches mean length were released in autumn and larger fish of 5f-inches
were releasecl in spring. Although over fir'e times as many o{ the large fish were
taken by anglers, tl.re cost þer fslt, creeled was tl¡ree times as great in the case of
the larger fish.
Wales (1946) has shown with reference to fingerlings of 1.5 to 3 inches ancl
yearlings of 6 to 7 inches, stocked in a Californian lake, that in the case of brown
trout added costs of producing larger fish were roughly proportionate to the
increase in survival value. \Mith rainbor,v ancl brook trout in the same lake an
advantage was gained because the survival value of the year'lings exceeded that of
fingerlings by relatively more than the costs increased.
It is apparent that relative costs of production of fish of different sizes rnay vary
from place to place and that the relative expectancies of life of fish of different sizes
ancl of clifferent species may vary according to conditiåns offering. Present evidence
does not indicate that investmsnf ç'f money on large fingerlings or yearlings, rather
than on production of fry, usually results in a greater benefit to the angler,
although occasionally it may do so.
In this as in most other branches of fishery management there is need for strict
costing of operations ancl for careful lreasurement of results if management is to
be otherwise than highly speculative. ltro private citizen or- trading corporation
could afford to run a business r'vith the disregard for costs and the extraordinary
absence of inforrnation on results occurring {rom the investment of money r'r'hich
has characterizecl the so-called management of fisheries by State Departrnents and
various organizations in this collntry and in others.
Fingerlings and Larger Fish in U.S.A.
Grorving know'ledge of the contribution to stocks from natural reproduction,
clissatisfaction with results obtained in streams frotn release of fry in New Zealand
and in the lJnited States of America have led to a demand for more ancl bigger'
frsh. In the United States there is no generally accepted policy in this matter. Tl-re
few States r,vhere substantial proportions of the trr.¡ut for release are helcl until they
reach legal size have not contributed substantially to the investigations citecl earlier,
which aim at learning the value of releasing fish. On the other hand, in Micl-rigan,
Fisheries bulletin (N.Z. Marine Dept.) no. 9 (1948)
I 103