Crabby About The Derwent

One of my favourite trout fisheries is the lower Derwent Estuary from Bridgewater downstream to Hobart’s postcard-perfect Tasman Bridge (see FL#46). Traditionally, the highlight was the early-season whitebait run, the accepted wisdom being that the fishing would be fully underway by opening day in August and would keep going strong until October, after which it would be better to join the fray in the Central Highlands where wet fly fishing would be gaining momentum. As a youngster I accepted this lore without question, more’s the pity.

Even though whitebait feeders can sometimes be hard to catch, they are easily seen. You expect to find them swirling over the gravel flats or charging around further out, often causing frightened baitfish to erupt in showers. When the trout are less active, you tend to spook them out of the shallows or else they appear from nowhere to bow-wave after wet flies. With all this action, most people, me included, didn’t bother too much about polaroiding: the fish were most active early in the morning and late in the evening, and anyway, the visibility in late winter and early spring was compromised by the mottled substrate, overcast skies and low sun. 


Over the years the whitebait runs have become more drawn out. These days they don’t really start until early September and often continue in dribs and drabs until Christmas. And, perhaps because they go for longer, they are less intense than they used to be: in the lower estuary, at least, you often have to search harder for your fish. 

Fishing in October and November was a revelation to me. The sky was often quite clear, the winds had stabilised, and come mid-morning, the sun was high enough to keep everything out of shadow. On the days when I struggled to find whitebait, I would subconsciously default to my preferred modus operandi: polaroiding. Inevitably I began wading over rock shelves and along gravel flats, and often, glancing back in to shore, I would spot fish. 

These silvery trout were always cruising slowly, sucking stuff off the bottom. They mostly ignored small schools of whitebait, even those that coalesced around them. They mostly ignored my flies too. The only response, if I got one at all, would be for the fish to deviate around the fly then idle back onto its original beat. The trout were so focused that they didn’t seem to realise I was there unless my shadow fell across them or they swam bang into my legs. 

Sometimes I’d cover the fish a couple of dozen times over fifty metres or so, usually for no result. Sometimes I’d swap whitebait patterns for Irish sea trout flies or various nymphs, usually for no result. 


I’d gutted a lot of fish in my early years of estuary fishing so I was well aware that Derwent sea trout — even whitebait feeders — ate plenty of Paratya shrimps and crabs, but ‘perfect’ imitations of these critters worked no better than anything else. No matter what I did, I could not hook more than about one in a dozen of the fish I cast to.

At the time that I was getting serious about polaroiding on the Derwent, I had pretty much stopped killing the local trout: I’d grown rather fond of seeing the same old fish in the same old places and enjoyed the prospect of outwitting at least some of them more than once each season. Eventually, however, I felt compelled to check a few guts just to reassure myself I hadn’t missed any vital clues. 

The first few fish I killed happened to be feeding mid-water on the edge of the drop off, either picking things off the sides of basalt walls or filter feeding like whale sharks. Their guts were full of Paratya and various crabs, and if there was a clue to be found amongst this potpourri, I couldn’t see it. 

I sensed that the fish on my favourite flats were behaving slightly differently to the ones cruising the lips. Gut samples revealed that these fish were feeding solely on crabs. Not only that, they were selecting only one species from several that were common. 

I tied ever more elaborate crab patterns, but my catch rate failed to improve. I tried ever more elaborate presentation tricks, and still my catch rate failed to improve.


Maybe the trigger was leg movement? Maybe visuals didn’t matter so much as sounds? Scurry sounds? Claw clicks? Smell perhaps? To test these possibilities — just as an experiment, you understand — I put a natural crab on a hook. 

Things didn’t change. Well, some things changed. My mates started offering me forked sticks on which to set up my rod. And they began wondering loudly amongst themselves if they should save their beer cans for strike indicators. One even made me a T-shirt emblazoned CRABMAN. 

Then one day, an epiphany: the crabs in any one gut were always exactly the same size. This was despite the fact that there was always a range of crab sizes present on any shore. Eventually it became apparent that the trout always targeted the biggest crabs found on their particular beat. To be precise, they targeted the biggest crabs that could be found in good numbers. 

So I began to use a crab the size of a ten-cent piece on this shore and a crab the size of a twenty-cent piece on that shore. Some times a five-cent crab was called for, or even a fifty-center. My catch rate went from one in a dozen to one in five.

Luckily I soon realised that you don’t need to kill fish to work out what size crab to use. The crabs are never obvious in the water, but all you have to do is upturn half a dozen rocks: the appropriate ‘common large’ size is usually obvious. 


My mates immediately assumed that my re-found zeal for catch and release was the reason I stopped using natural crabs. Bait fishing, however, is only problematic if the trout are swallowing the bait: I was fishing natural crabs exactly like artificial flies, striking the moment the fish closed its mouth. 

The real reason I resumed fishing with imitations was a matter of ‘integrity’, though exactly what that is I can’t decide. Anyway, my intention had always been to narrow down the variables so that I could come up with a ‘functional’ artificial crab.
The most important thing turned out to be size and rough shape, but other refinements were required. I wasn’t too worried about matching the exact colour, but I figured that a ‘natural’ brown was probably better than, say, fluoro pink. It was also important that the fly sank at the right rate because it had to be on the bottom when the fish approached. And it had to sit ‘hook up’ so it didn’t snag on the mussels and oysters. 

After trialling many patterns, I settled upon the Permit Crab described by Chris Beech in FlyLife #70. I use a neutral coloured Furry Foam (cream or white), colour the body brown with permanent marker, and tie on 5/32 recessed Real-Eyes. Among the many things I like about this pattern are the suede chenille claws and the silicone legs, which twitch in a life-like manner and make me think the fish should eat it. I learned long ago that, just as important as having a fly the fish believes in, I have to have a fly I believe in.


Of course, having a reliable imitation is still only part of the deal. You also have to develop a feel for exactly how to present the fly to individual fish, and how to alter the presentation according to the fish’s individual behaviour. 

Usually I lead the target by two or three metres and hope to have the fly on the bottom before the trout realises it is there. If the fish doesn’t see the fly, the next cast may be the same as the first, but with a slight twitch. Sometimes I resort to giving the fly a short strip. But I suspect that successful presentation is a lot like successful polaroiding — a knowledgeable angler can tell you the basics, but you need lots of practice and experience in order for your subconscious to be able to instantly make the appropriate calibrations. 

In any case I now have more success with artificial crabs than I ever did with natural ones, averaging one fish on the bank for every three I cast to. This often equates to landing two or three fish during a session. Most weigh 2–5 pounds, and the majority are silvery. Not bad in the middle of suburbia. And I usually have the fishing entirely to myself.


The easiest time to fish is from early October to early January, when the density of fish is at its peak and the sun is high enough to allow good visibility. High summer provides even better polaroiding conditions but can be a bit hit and miss. I suspect that temperature has something to do with it, even if my best-ever day was a 35- degree scorcher in early February. 

Autumn (mid-March through to late May) is consistently good, but polaroiding becomes more difficult and the fish are rarely as prolific as they were in spring and early summer. Winter (June, July, August) sees the sun so low that some of the best shores are never out of shadow. Nevertheless, there are always reasonable numbers of fish cruising close in, so it’s just a matter of honing your stalking skills. 

Very low tides which completely expose the crab flats are bad news: the fish drop off into deeper water and are difficult to spot. Also, they begin to favour Paratya over crabs, which makes them next to impossible to catch. On very high tides, some of my favourite shores are difficult to wade, and the fish — being deeper down — can be relatively difficult to see. What you really want is 15–60 cm of water over the flats, and luckily this is how things are 80% of the time.

Traditionally most Derwent anglers fished from dusk into the night. I do less night fishing these days, especially if the fish are not feeding in a showy manner on baitfish. Why fish blind at night when you get much better results polaroiding in the day?

Early morning is usually calm, so if you are good at spotting fish when the sun is low, this is a good time to fish. Visibility improves as the sun edges higher, and the fish become almost spook-proof when the sun is at its highest, but a stiff sea breeze is to be expected by noon — big waves stir up the bottom and can make polaroiding all that much harder.

In general, the saltier the surface water, the more active the crabs and trout. Floods are bad news. The water quickly becomes discoloured with tannin and silt, and even when it clears it often takes a week or more for the fish to return to the shallows. 


I see more fish in the lower Derwent estuary than I see in the Nineteen Lagoons, and they are usually bigger and in better condition. Still, the Derwent is not a place for novice polaroiders to build confidence. When conditions are tough — when there’s rain, cloud, riffle or shadow — the polaroiding is super tough. Even on perfect days, newcomers often struggle. And crab feeders simply cannot be taken by fishing blind: it’s hard enough to get them to react to your fly even if you land it on their head. The thing to remember is that the fish are usually there: if you are not seeing them, the chances are that you are overlooking them. So, what tips can I offer?

On many of my favourite shores you are obliged to wade and polaroid back into the bank. The importance of this cannot be overemphasised. 

In cloudy or riffly conditions it is easy to miss fish when scanning and you rely heavily on other clues. Always be on the lookout for dimpling baitfish, a slight bulging of water, anomalies in the waves or a hint of tail. If you know roughly where a fish is, you can often polaroid it even if visibility is poor. 

Another thing is to discipline yourself to look into shadow. This is harder than you might think, but often essential. 


The hot spots are the same ones I’ve advocated over the years: places like Rose Bay, Lindisfarne Bay, Cornelian Bay, Dowsings Point, the foreshore at Risdon (Store Point), Otago Bay and Wilkinsons Point.


The crab thing has reminded me of the desirability of difficult fishing. The only reason I still fish the Derwent as much as I do is that I still have a lot of room for improvement. Difficult fishing is addictive in a way that easy fishing is not.

The crab thing has also made me wonder about the diminished role of radical experimentation in modern fly fishing (tinkering with existing fly patterns doesn’t count). I wonder if this has come about because fewer anglers arrive at fly fishing after an evolution through active bait fishing and spinning? Does this make them more susceptible to purism and less likely to stretch the boundaries? Or does modern conservatism come about because so much information is now so readily available that we are no longer obliged to work things out for ourselves? 

Anyway, here’s a challenge: can anyone out there come up with a reliable way of catching Paratya feeders? Believe me, success will involve much more than developing a realistic fly. If you suss it out before I do, why not write about it for FlyLife?

From FyLife Issue 74