Category: High Risk
WITHOUT doubt the dhufish, or dhuie as it's generally known these days, is the icon of the southern recreational boat fishery. Many anglers put to sea solely to pursue these tough, solid-looking fish with a mauve hue over their big silver scales. Larger males have an extended first dorsal fin filament, which is absent on females. They are regarded almost universally among fish lovers as being one of the best eating fish in the sea - and quite correctly so. Their flesh is white and flakey and, if handled well after capture, has a sweetness and creamyness not found in any other species. A feed of dhufish fillets is guaranteed to make most fish eaters happy.
Some people do say that they don't taste quite as good as they used to when they were called, more historically correctly, Westralian jewfish! Wiser men than us, based in Canberra, decided that our jewfish, or jewie, should be renamed so as not to confuse seafood diners on the east coast who might think they were eating mulloway, which they call jewies! Doh!
Dhufish are not too difficult to identify with their robust body and proportionately big head. Generally ranging in colour from a bright silver through to grey, they frequently have a mauve, almost metallic tinge, especially in larger specimens. They are also easily identified by a black line running through the eye, though this is often hard to see on larger fish. Juveniles are the most handsome of fish with grey/black stripes running down their bodies and a very obvious black line through their big eyes.
Dhufish grow to a very respectable size, which no doubt adds to their appeal as both a recreational and commercial target species. In Sea Fishes of Southern Australia (Dr Barry Hutchins and Roger Swainston) dhufish are reported to have been caught up to 25.85 kilos. In most parts of southern Western Australia these days a ten-kilo fish lights up anglers' faces, a 15-kilo dhuie is talked about and a 20-kilo specimen is a monster. Increasingly, though, each trip out produces a number of fish that are less than the legal minimum size of 50cm, which is not a good sign for their stock status.
Dhufish are exclusive to WA and range from the Recherche Archipelago off Esperance up to about Shark Bay. Farther north, a smaller species of "pearl perch" occurs and is a commercial target, particularly off the Pilbara coast. Dhufish spend much of their lives in shallowish inshore waters where they inhabit reefs, caves and gutters. They favour structure for most of the year but there are times when they can be found in numbers away from reefs over flat coral country and even over sand when they are breeding.
Breeding and migration
Adult dhufish move into shallow reef areas in the cooler months, between April and June. Spawning occurs from December to March with the peak period in January and February when water temperatures are high and plankton is abundant. However, the spawning itself appears to actually take place over isolated reef outcrops and weed-covered sandy substrates. A large female dhufish can lay up to three million eggs pelagic eggs which float away. Juveniles feed on plankton and remain in shallow water. At one year old a dhufish is around 12cm long and by the time it reaches two years it is 19-22cm, with males growing quicker than females. The growth rate then slows down somewhat after this initial two-year spurt and fish achieve lengths of between 40 and 45cm in their fifth year.
Recent research has shown that 50 per cent of females and males have reached maturity at 30-32cm respectively, with virtually all fish above 40cm being mature. Thus dhufish caught at the legal size limit of 50cm have spawned at least once. At 50cm dhuies are six to seven years old. Though the species spends the vast majority of its life in shallow waters, dhuies are also known to head out past the Continental Shelf into depths of more than 200 metres. Little is known about this deep water migration.The diet of adult dhuies is primarily small fish but they also eat their share of rock lobsters, squid, cuttlefish and octopus.
Again it has to be said that the single most significant threat to this superb species is recreational and commercial overfishing. Dhufish are one of the most popular offshore targets for recreational anglers. During 1996/97, the year of the recreational survey between Augusta and Kalbarri, about 132 tonnes were reported and retained, with a further 65 tonnes released as undersize (or in excess of the bag limit) by recreational fishers. The commercial catch during the same year, and from the same region, was an estimated 191 tonnes and was taken by wetline, demersal gillnet and longline as well as by other vessels with an open West Coast licence, such as crayfishermen. It is not known what quantity was released in the commercial sector.
Concern in the recreational sector about the number of commercial operators able to access dhufish, and other valuable finfish stocks, resulted in a benchmark date being declared by the Fisheries Minister in November 1997. An extensive review of this, and other fisheries in WA, is under way as part of the Integrated Fisheries Management Plan being implemented by Fisheries WA. One problem encountered by anglers is the apparent inability of some undersized dhufish to recover when pulled from depths of 20 metres or more. The problem is air embolism, which often ruptures the swim bladder and forces the fish's stomach out through its mouth. It also bursts blood vessels in vital organs including the brain. Research is under way to work out a strategy to overcome this mortality of immature dhufish.
Tackle and bait
I am a fan of drifting a floating bait in a berley trail but it is probably not the most effective way to catch big dhuies consistently. For that the drift method still reigns supreme. The favoured rig for such drift fishing is the dropper loop or paternoster. Most dhufish specialists I know use a single hook on the top dropper and a pair of hooks on the bottom to carry bigger bait. The hook sizes and configurations vary from angler to angler, but their secret to success is always the same - just keep going fishing and learning! Big fresh baits are the go for big dhuies. My personal preference is for the natural fish bait you can catch on the way to the fishing grounds. In particular I like small whiting, which is high on the dhuie's menu. Octopus with all the slimy skin cut off, mulies, fish fillets and squid can all be good baits on the day. My gear consists of a short, soft action 15kg overhead with 36kg braid and a 24kg mono topshot in case I get snagged. Hooks should be sharpened and resharpened during fishing so that when that a dhuie sucks in your bait you can set the hook. Try not to bury the hook points in big baits.
Look for reef structure or hard coral bottom and drift. Often a sea anchor is essential to stop the boat drifting too quickly in the breeze. A fast moving boat makes it difficult, if not impossible, to hold bottom without huge sinkers and staying in touch with the bottom is important to this fishing method. Don't just drift around blindly either. Mark your spot on your GPS or drop a marker over the side (it's still a good way to fish), then start drifting upwind. Monitor the direction and speed of your drift and then allow for any unforeseen changes in direction with your next drift. If you do end up fishing near cray pots, please mark the float line if you inadvertently snag one and leave a rig on the cray rope. Sinkers kill and maim commercial fishermen every year so make a habit of marking their ropes if it happens to you.
References: Kailola, Williams, Stewart, Reichelt, McNee and Grieve Australian Fisheries Resources 1993. Hutchins and Swainston Sea Fishes of Southern Australia 1986.