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

,.)
in rivers of considerable size bút of variable flow which lack falls or gorge sections
of steep gradient. Cor-rtrol of eels may prove practicable where volume is fairly
legular ancl gradient is considerable. Outlet streatns of lakes often offer both these
conditions. Given these conditions, it should be possible to employ the knowledge
thãt eels are unable to slvirn aga.inst the current up which trout may pass. This
calls for the confining of streams, possibly by weirs with "V"-shaped apertures
in them, the height of the weir ancl the angle of the "V" being sucl-r as to ensure
a sufÊcient current at all levels. Where the gradient is great enough, regulation
and direction of flow may alone be sufñcient. Where the natural fall is less, the
ir-npounding of waters behind rveirs with overhanging siils may make an effective
barrier. In still more sluggish waters, the seasonal trapping of migrants may havc
to be done.
There is need for additional knowledge as to what are the cheapest antl most
elïective forrns of eel-barrier for waters of different type. Among waters $'el1
suited to experimer-rtal modifications are the outlet streams of certain lakes irr
the Canterbury and Otago provinces.
GE}trERAL COMMENT
It is emphasized that over a very lor.rg period the bulk of the anglers' liccuce
fees has been spent on w'ork nor'v found to be of a highly speculative character.
The various possibilities of mo.Jifying physical environurents cliscttssecl in this
section relate to ¡1'pes of project rvhich, while speculative, are justifiable i{ regarcled
as experiments and if so plar-urecl that the costs and the lesults obtainecl may be
appraisecl.
Essentially there is need for appreciation of the paucity of funds which
could be used for physical modification of environments and of the fact
that, if economic dividends are to be obtained, they will arise from intelligent
use of 'opportunities which different natural features in some places
present.
Fis.hery Protection
POACHII{G
For rnany years the protectiorLr of stocks of trout during the spar,r'uing seasoll
lras been a grossly neglectecl duty in many parts of New Zealand,. Basiczrlly, the
reasolls for this are-
( 1) Local management is in tl-re hands of couucils of licence-holders. rvho iu
nìost areas are personalll' a.,tuu'tlred with conditions only in the augling
season.
(2) The enforcernent of restraints of angling technique during the angling
seasolr often tends to assume an exaggerated ilnportattce, because, again,
members of councils have more personal acqr:aintance rvith breaches oi
regulations lvhich occur in season than lvith ont-of-season breaches.
(3) The extr-aordinary preoccrlpation with the u'elfare of the few eggs which
may be seen in hatcheries has often blir-rded cour-rcillors to the fact that such
eggs are usually onlv an insignificant fraction of the greater nutnbernaturaliy
spar,vnecl ancl therefore not observecl. (Note: In some districts it
has long been the practice to recall employees irorr field patrol duties ar-rci
to tie tl-rem down to hatchery work at the very tinle of the year when trout
becoue most vulnerable to poaching')
Fisheries bulletin (N.Z. Marine Dept.) no. 9 (1948)
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