Yes, there is salmon fishing up river. It is quite popular, two years ago I caught a nice 7.7lb Salmon while spinning for trout although I live in Marlborough which is the northern edge of the Salmon runs.
We also have a population of sea run brown trout. The enter the rivers early spring chasing baitfish. Late in the summer they enter again and head upstream to spawn.
I have only been trout fishing for 2-3 years but I am quite passionate about it. Marlborough has quite a few good rivers to fish.
The largest river is the Wairau, it is 140km long and most braided. It holds good populations of brown trout and a few rainbows. There can be good fishing for sea run brown trout near the mouth.
The middle reaches are quite boring, although do hold good numbers of fish where the water is stable.
The upper reaches and headwaters are secnic and a excellent brown trout fishery. Trophy size trout are not unheard of. Although the river is swift and fast flowing in these parts.
The second main river in Marlborough is the Pelorus. The lower reaches holds good number of both Rainbow and Brown trout. The upper reaches are a series of deep crystal clear ponds which hold few fish but the ones which are there are normally big.
The main tributary of the Pelorus is the Rai, this river holds a amazing number of trout. although many of them are small.
If the rivers are in flood, the best place to fish is a small river called Spring Creek. The water is clear and the river holds a large number of good size fish.
There are many other rivers and options in Blenheim and I have only given a quick overview of three of the key rivers. The website NZfishing.com has good information and so does the ‘book’ Southh Island Trout Fishing Guide – John Kent.
With regards to equipment. I use a 6wt 9ft rod for fly fishing. It handles 90% of the conditions just fine. Your 7ft would probably be alright on all but the smallest of streams. If possible I would use a lighter spinning rod for freshwater fishing.
A floating line is important, along with tippit material in 3x and 4x. I like to use “AirFlo Floating Poly Leader 5ft”. Then to that I tie a couple of feet of 0X tippit material and to that I 4-5 feet of 3x or 4x material.
This leader set-up seems to work well and I find it handles the wind better then the more traditional tapered leaders and is more forgiven on my poor casting techqnuie.
Fly Selection i like to have.
Pheasant Tail Nymph in sizes 12-16 with 16 being my favourite. Tungsten beadheads are also useful to get the Nymph down quickly.
Hare & Copper Nympth in simalar sizes.
Maybe a few Stone Fly nympths if you plan to fish the headwaters.
For Streams the best option is the Wooly Bugger, in sizes 2-6.
Having a selection of Dry Flys is also handy. December is still a bit early for ‘large terrestrial fishing’.
Now onto the Marlborough sounds.
The inner queen charolete sounds hold few fish, and you really need a boat and fish the ‘headlands and outer bays to catch decent number of blue cod.
The Pelerous sound should have Snapper in it at this time of year, they are quite hit and miss but they are decent fighters.
There would also be a range of other saltwater fish present.
There is a lot of information and it would take to long to write it all here.