Tasmania's Beautiful Brookies
by Greg French
Brook trout, with their olive backs, lemon spots and, in the case of spawners, bright orange flanks are perhaps the most strikingly beautiful of all salmonoids and, because they are so rare in Australia and New Zealand, most anglers aspire to catch one. While the species does not offer the same challenge as the ever cunning brown trout, it is highly regarded in its native North America and we are privileged to have a couple of wild populations in Tasmania.
Why are brook trout so rare?
Even established brook trout only fisheries have collapsed once other trout have been introduced. Late last century (probably in 1889) Lake Leake was stocked with brookies and it seems that a viable wild fishery was maintained until shortly after the introduction of rainbow trout in 1904. The subsequent collapse of the brook trout fishery is hardly surprising given that, even in the USA and Canada, browns and rainbows have caused the demise of countless native brook trout populations.
In Tasmania there have been several attempts to maintain put and take fisheries (waters where fishing is maintained by regular stocking). Impoundments such as Briseis Hole, Vaucluse Reservoir, Edgar Pond and Lake Dulverton, not to mention a number of farm dams, yielded good fish and were reasonably productive but there was a great difficulty in producing regular and worthwhile supplies of hatchery reared stock and the programs were eventually dropped. In recent years the emphasis has shifted towards establishing viable wild fisheries.
Rearing in hatcheries
From the outset there has been an undersupply of ova. The number of brood stock which can be held at the Salmon Ponds hatchery is limited and the quality of eggs and milt has always been poor. Better ova can be obtained from wild fish but locating spawners is both difficult and labour intensive.
The poor survival of ova and fry proved to be an ongoing problem. Even today, despite significant advances in aquaculture technology, some 90-95% of ova fails to hatch compared with less than 2% for brown trout ova collected from wild spawners. Furthermore, 50% or more of the sac fry die before the swim up stage and significant losses continue until the time of release. Consequently, maintaining annual stocks of fingerling brook trout is both labour intensive and impossible to guarantee.
Many of the brood fish at Salmon Ponds would be fifteenth generation hatchery reared descendants from the original 1962 importation. Given that the hatchery population has on occasion been reduced to just a handful of adults, it had long been suspected that the stock was inbred and inferior. However, live ova and adults have occasionally been transported to the hatchery from the wild population at Clarence Lagoon and recent research has shown that, not only are Tasmanian brookies essentially very healthy, but they display an extraordinary amount of genetic diversity, even more than can be detected in our wild brown trout.
The problems with hatchery ova may simply relate to warm water which probably affects the development of eggs and milt prior to spawning as well as the progress of newly fertilized ova. This augers well for the long-term well being of the two fisheries in Tasmania where natural recruitment is known to occur.
Spawning and Growth
It is common for brook trout to mature early, males in their first year and females in their second. Fish that have spawned lost strength and, where food and space are limited, they find it difficult to compete with the immature population. Consequently, brook trout from over populated creeks are often extremely stunted. In fact the fish I have taken from several tiny creeks in New Zealand have averaged no more than 120 or 150 mm. Nonetheless, in waters where competition is low, brook trout can grow faster than is normal for wither browns or rainbows. In Tasmania and New Zealand lake fish commonly attain 2 kg or so and occasionally exceed 4 kg. The biggest brook trout ever taken may well be the 14 Â½ lb, monster taken from the NipigonRiver in Ontario in 1916.
The Anthony lakes
Of the hydro impoundments the only water of interest to anglers is the main storage, Lake Plimsoll. This 47 m deep lake, completed in 1993, suffers dramatic fluctuations in water level, but supports plenty of good-sized fish and is probably the most productive wild brook trout fishery in Australia and New Zealand.
Lake Rolleston is a large natural lake located about 2 km upstream of Plimsoll. It is a headwater lake but natural spawning occurs in its sizable outflow and in several of its small tributary creeks. Fish to 2 kg and more are relatively common. Access is via 6 km of rough vehicular track. The other fishery of note is Lake Selina. This small water lies at the head of a minor tributary creek, 15 minutes walk from the western shore of Lake Plimsoll. Spawning is mediocre and the fishing, though very good at times, is probably largely maintained by artificial stocking.
Tactics for Tasmanian brookies
While brook trout will take food from the surface and occasionally rise well, they appear to be more predisposed than other trout to feeding from the bottom. This behaviour is exacerbated because in summer the fish tend to avoid warm surface water.
Undoubtedly the most consistent lure fishing occurs during rough cold conditions early and lake in the season. In warmer, calmer weather it pays to concentrate your fishing at dawn and dusk. In deeper waters, such as Plimsoll and Rolleston, fishing deep may be advantageous.
For the fly enthusiast persistent prospecting with a wet is the most likely way to catch an exclusive brookie or two. All shorelines produce fish, but hot spots are in the currents of inflows and outflows. As with spinning and trolling, the biggest bags are taken in Spring and Autumn, most commonly during periods of low light. Quite often in April you will find pre-spawners milling about in the shallows, especially in areas adjacent to the mouths of the main spawning creeks. Daytime risers are suckers for a big dry (try a Red Tag or Royal Wulff) and even respond well to bulky wet flies. At dusk, Sloane-style Fur Flies and corks are all you will ever need. You are most likely to find fish rising shortly after a liberation of fingerlings (from Christmas to late April). These fish are usually very small (under 300 g) and should be released. Adult fish rise infrequently buy provide memorable sport when they do. I have found the odd fish working on beetles and spinners as early as September, but the best fishing has always been during summer when the air has been warm and still. The very best action I have encountered has been post Christmas in the Anthony lakes during the mudeye migrations.
Mind you, the rise remains quite unpredictable and locals seem to prefer fishing for browns and rainbows at Lake Burbury where success is all but guaranteed.
All of the Tasmanian brook trout fisheries are tea coloured and none provide exceptional polaroiding. However, Clarence Lagoon can become quite clear when levels are low and at such times proficient scanning is the surest way to succeed. Fast accurate presentations ahead of faint shadows and flickers of white-tipped fins bring certain responses.
Lake Selina features some very good looking polaroiding water, and those fish which stray into the shallow water are indeed easy to spot, but unfortunately most fish prefer to feed offshore.