Home' Fish and Game : August 2015 Contents Lake Thomas Update
S MOST OF YOU WILL KNOW, CONCERN
remains for the health of the Waituna Lagoon.
Environment Southland has recently released
a 2013 report on the Ecological Guidelines for
Waituna Lagoon and unfortunately it isn’t good news
(Google ‘Ecological Guidelines for Waituna Lagoon’
or search the Environment Southland websitehttp://
logical_guidelines.pdf). The report was prepared by
the ‘Lagoon Technical Group’ (LTG) which included
the foremost national experts in the relevant scientific
The report reaches three main conclusions;
• an objective of maintaining a healthy macrophyte
community because it is a key indicator of a healthy
• a 50% reduction in N and P inputs to the lagoon
• an opening regime that minimises the risk of the
lagoon being open during spring and summer (Au-
gust to March).
Sea-run or ‘lagoon-type’ fish?
Historically, anglers always favoured the lagoon
being open to the sea, particularly over the
start of the fishing season. Many still favour it open
STU SUTHERLAND, WHO HAS BEEN THE SOUTHLAND FISH & GAME FIELD
Officer based in Lumsden since 1973, retired in April this year.
Stu has been responsible for looking after the sports fish and game resources in
the northern part of Southland. This area includes some world famous trout fisher-
ies. Duck hunting is also very productive there and many of the better ponds have
been constructed under Stu’s supervision. Stu’s work accomplishments are many.
His institutional knowledge, work ethic, good humour, and quirk of including half a
banana every lunch will long be missed.
MY NAME IS COHEN STEWART AND I AM THE NEWEST ADDITION TO THE
Southland Fish & Game team. I moved to Invercargill from the North Island
when I was 12 and quickly discovered the superb trout fishing. I started off bait and
spin fishing on the lower reaches of our major rivers and as I got older, moved to
flyfishing rivers and streams throughout Southland. Like many Fish & Game staff,
it was my interest in trout fishing which influenced my decision to study ecology at
university. I am looking forward to fishing local rivers that are close to home and
meeting many out on the water this coming season.
WHERE ARE WE WITH WAITUNA?
STU SUTHERLAND RETIRES
NEW FISH & GAME OFFICER
By Bill Jarvie, Fish & Game Officer (Te Anau)
Annual stocking of rainbow fingerlings into Lake Thomas
AKE THOMAS, SITTING AT 500M A.S.L 19KM
east of Te Anau, has always been a fishery visited
by a relatively small number of anglers. This
may be because of its exposed nature, or perhaps
more likely due to uncertainty of public access.
We couldn’t do anything about the former,
but now the issue of vehicle access has been sort-
ed. Rather than the problematic original route
through Landcorp’s Mararoa Station from the
Mararoa River, a shorter and more straightfor-
ward option has been settled on.
Fish & Game and Landcorp have agreed that
anglers’ access would be better via the well main-
tained farm lane from the end of Danby Rd (off
Lagoon Ck Rd). Just 1.7km from the road end
there is a parking spot beside the lake. From there
it is foot access-only around the lake margin. Non-
motorised watercraft can be easily launched at this
point via a farm gate at the water’s edge.
Fish & Game has recently opened up a foot
track along the first few hundred metres of the
eastern lake edge. This will ease the access and be
welcomed by families with younger anglers.
Historically known for the occasional very large
trout, the lake has no spawning tributaries. Lim-
ited natural recruitment comes with lake edge
Fish & Game augments this with annual re-
leases of fingerlings to boost angler returns.Lake
Thomas is open year round and all legal baits may
By Zane Moss, Operations Manager
to the sea, with a lot believing it benefits the fish-
ing because it allows sea-run fish to enter the lagoon.
However, observations suggest that by far the ma-
jority of fish that are captured at the ‘break-out’ are
actually lagoon-type fish rather than true sea-run fish
(M. Sutton pers. comm). These are fish that may well
feed in the sea for short periods, but are thought to
be primarily attracted to the concentration of bait fish
at the mouth. They retain the majority of their lagoon
colouration and do not display the same markings as
true sea-run trout. While there are the occasional
sea-run fish caught, they represent less than 10% of
the angler harvest.
The average size and condition of Waituna fish re-
mains larger than any of Southland’s true estuarine
fisheries. This suggests the trout attain their size from
the food associated with the lagoon itself, such as
the abundant shrimp, various native fish, koura, and
invertebrates. These species will be most abundant
when the lagoon is healthy.
Why don’t Fish & Game want it open to the
sea over the fishing season?
The Ecological Guidelines report identifies the
critical role that Ruppia (an aquatic plant) plays
in the ecology and health of the lagoon. Ruppia helps
regulate water quality in a number of ways, including
the uptake of nutrients for its own growth and with the
stabilisation and oxygenation of sediments by its roots.
Ruppia also provides habitat for fish and invertebrates,
and food for grazing birds. The LTG recognises that Rup-
pia is so critical to lagoon health that it should be spe-
cifically monitored as a surrogate for ecosystem health.
A serious threat to Ruppia health is the lagoon being
open over the summer period. At low tide, Ruppia is
desiccated by the sun and much of it is also exposed
to water with too higher salinity. Also, Ruppia seeds
over the summer, which it won’t do successfully when
the lagoon is tidal.
Research commissioned by Environment Southland
suggests that the lagoon is very unlikely to close until
the following winter if it is opened after July. There-
fore, because of the potential risk to the health of
the Ruppia, the ecosystem and the trout fishery, Fish
& Game supports the LTG’s recommendations for an
opening regime that minimises the ‘risk’ of a spring or
summer opening. While such a stance may not meet
with universal approval from anglers, hopefully they
will accept it is for the medium and long term survival
of this great fishery.
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