Rob Sloane takes a closer look at Tasmanian ‘shrimp’ feeders.

A highlight of the Tasmanian fishery is stalking trout in shallow lake margins. Early in the season, rising water levels can bring fish in for all sorts of reasons—worms, grubs, frogs and later tadpoles, for example. These fish are keen, hungry and confident and will usually respond to rough presentations and all manner of hairy or woolly flies.

But as the season progresses and water levels settle and begin to fall, ‘tailing’ fish become harder to find and invariably harder to catch. Without this flush of terrestrial life and the security of rising water, there has to be a good reason for trout to venture in close and, more often than not, aquatic crustaceans are involved.

SHRIMPS AIN’T SHRIMPS
“They’re feedin’ on shrimps,” is a typical greeting from an angler sloshing back through the shallows after a successful dawn patrol on a Tasmanian lake. Little shrimps, big shrimps, mountain shrimps and green shrimps are commonly used but hardly adequate descriptions when it comes to the creepy-crawly crustaceans that fall prey to trout. Sorting out the differences really is not that difficult and conveys vital information if you intend tying flies and devising ways of catching ‘shrimp’ feeders.

One word of caution for keen analysts of trout stomach contents is that the colour and shape of partially digested or alcohol preserved crustaceans can be very misleading, so it always pays to refer to active, live specimens if contemplating some new creation at the fly-tying vice.

PARATYA—FRESHWATER SHRIMP
Lowland lakes and the slow flowing, lower reaches of weedy rivers are the most likely places to find trout feeding on the true freshwater shrimp Paratya. These really look and behave like ‘shrimps’, having a well defined carapace, translucent body and a vigorous backward-flicking escape response. They are classified in the order Decapoda, which includes the more familiar prawns, crabs and crayfish.

Paratya can grow to a decent size (20–40 mm) and are fast movers when disturbed. Aggregations will stir the water and even sprinkle out like a school of whitebait as trout hunt through the weed beds.

The more realistic imitations are based around the saltwater Ultra Shrimp pattern (FL#26), but for those not keen to dabble with epoxy, various standard whitebait patterns will do the job just as well.

A white or grey BMS is hard to beat and can be cast to a disturbance, allowed to settle and then stripped back quite actively. The Keam Shrimp (Australia’s Best Trout Flies: 1997) is a more realistic alternative.

ANASPIDES—MOUNTAIN SHRIMP
As the name suggests, these are found in the high country, with the Western Lakes being a particular stronghold. Endemic to Tasmania, Anaspides tasmaniae belongs to the primitive Syncarid group and has a rather elongated, segmented body with no distinct carapace. In mountain streams and runnels Anaspides is only found in significant numbers in the extreme headwaters beyond the distribution of predatory fish (native galaxia and trout) but in alpine tarns they coexist, with the shrimps leading a cryptic existence amongst the rocks. They can grow to little-finger length (50 mm), so large, hairy, nymph-like imitations are the go.

Trout feeding on mountain shrimps are generally found bow-waving across gravelly shallows, cruising in tight against rocky shores, or lying in wait around the mouths of inflowing runnels. Hunting these fish is akin to stalking tadpole feeders, requiring stealth, patience and fast, accurate delivery. Look for them in overcast, drizzly weather, or early and late in the day.

A closely related Syncarid, Paranaspides is also found in the deeper waters of highland lakes, particularly Arthurs and Great Lake. These are a little smaller, less pigmented and a little more ‘shrimp-like’ in appearance. Being associated with deeper weed beds they are only seen in stomach contents and rarely targeted in terms of fly selection, although a small epoxy shrimp or white BMS fished on a sinking line would no doubt do the job.

AMPHIPODS—SCUDS
Amphipods are on the tiny side (5–10 mm) with a short, laterally compressed body and a rounded, hunch-back appearance. Natural colours are generally pale yellow to pale green. They are active swimmers and crawlers and often appear in mating couplets. Amphipods can be extremely abundant in lake shallows, particularly at Little Pine Lagoon and throughout the Little Pine River system in the Western Lakes, where hundreds can be picked up with one fistful of weed.

Trout ‘tailing’ on amphipods can be infuriatingly difficult to catch and may seem totally preoccupied. Repeated presentations to the same fish will often be ignored, even though the fish may only be a few rod lengths away. Inert presentation of ‘hoodwinker’ patterns is the recommended approach which is very much a part of Tasmanian lake-fishing folklore dating back to the early writings of Wigram and Scholes. The Fiery Brown Beetle has been my fly of choice over many seasons but more realistic scud imitations and small nymphs are popular. Diversionary tactics including fast-stripped wets and dry fly offerings can work in times of desperation, and the trout are generally more susceptible at dawn and dusk.

These days inert presentations are often aided by the use of dry-fly or on-line indicators, but the traditional approach demands an unnerving sense of take detection and timing which, in my experience, makes this the most demanding, and satisfying, manifestation of fly fishing.

Writing this, for me, is like Molly Meldrum watching re-runs of Countdown, but the trick is to cast the fly in the direct path of the fish, and just let it settle for the trout to find. If the fly lands just forcefully enough and just close enough to pique the trout’s interest, so it moves over to take a closer look, then you are in with just a chance. A deviation or movement towards the fly, then a slight but meaningful ‘shuffle’ as the fish picks it up, should be your signal to raise the rod with confident authority. If you are a chicken you can wait to see if the leader moves, but he who hesitates may barely prick the fish or miss the take altogether. Trout can suck and spit your hoodwinker in the blink of an eye.

ISOPODS—PHREATOICIDS
Often confused with amphipods, are the larger and more robust isopods (water slaters) belonging to the suborder Phreatoicidae which are common throughout the Tasmanian lake country but rarely encountered elsewhere. These are generally larger (10–20 mm), darker olive green in colour and have a more elongated body shape than amphipods. They tend to be crawlers rather than swimmers and their defensive posture is to curl up rather than flee.

Phreatoicids are a feature of silt bottomed tarns in the Western Lakes and offshore weed beds (shrimp beds) in the larger hydro storages. Suitable flies include specific imitations such as Murray Wilson’s life-like Scudrapod but you can make do with a Green Possum Nymph or a small green or black Woolly Worm pattern.

Bottom-creeping trout polaroided across the bed of waters such as Lake Botsford are almost certainly searching out phreatoicids which track across the silt and bury themselves therein. These can be targeted with flies weighted sufficiently to sink in front of the fish, then moved just enough to attract attention before being left inert for the trout to pick up.

The larger hydro-lakes such as Bronte Lagoon can be fished slow and deep over suitable weed beds by wading out or fishing from a boat. As water levels fall right back during late summer these shrimp beds become exposed and phreatoicid feeders may be seen tailing in the shallows at first light or polaroided in knee deep water during the middle of the day.

POSITIVE ID
Old time anglers often lament the trend towards nondescript flies and catch-all methods. You don’t need to know a great deal about aquatic invertebrates and trout behaviour to achieve reliable success with teams of surface flies or dredging the bottom with suspended nymphs or sunk-line Boobies. Likewise, tying a Red Tag or Woolly Bugger doesn’t involve a great deal of research or imagination.

Hopefully this little lesson about shrimps will demonstrate that there is a lot more to learn if you care to look. And with knowledge comes understanding. The ‘why’ is inevitably more interesting than the ‘how’ and extending your knowledge of the aquatic environment may help to take some of the guess work out of fly fishing.