Category: High Risk

BLACK jewfish are the northern cousins of the southern mulloway and can be found throughout the Pilbara and Kimberley regions. Their reputation amongst anglers is that they provide a brutish struggle, far more so than mulloway, with the ability to move into treacherous reef or rock formations in order to escape capture.

It has been suggested that the tendency for black jew to change from their silvery/grey livery to quite a dark grey upon death may well be how this species acquired its common name.

Surprisingly perhaps black jew is somewhat better on the table than its southern counterpart, mulloway.

Identification
Black jew are generally grey in colour, but when found in turquoise milky Kimberley waters they can have a silvery sheen to them. They have a convex caudal fin, almost pointed in some areas, whereas the mulloway has a flat paddle tail. Black jew also have a much narrower tail wrist than mulloway. They also lack the dark spot above the base of the pectoral fin that is so common with mulloway.

Size
Growing up to 45 kilos in weight, black jew are more commonly encountered in the 7 to 12-kilo range in places like Broome, but farther north size can range from small soapies through to monsters. Research carried out just over the border in the Northern Territory shows black jewfish in coastal waters grow extremely fast, reaching around 60cm in length in their first year and 90cm in their second year. It is reasonable, in the absence of similar research in Western Australia, to assume that black jew on the west coast would perform much the same. It was found that black jewfish live for at least 12 years with some specimens reaching 140-142cm. A 130cm black jew is viewed by some dedicated anglers as being commensurate with a trophy metre-plus barramundi.

Distribution
Black jew are found in waters from north of Onslow right across the north of Australia. They are a schooling species and most commonly found over soft bottom when offshore, seeking out deeper holes. Although they can be found in depths up to 100 metres they can also be found in coastal bays, estuaries and around river rock bars.

Breeding and migration
It is also interesting to note from NT research that 50 per cent of black jewfish are sexually mature at 89cm, which is two years old.

Spawning occurs over several months, starting around August and peaking in December.

Little is known about migration patterns of black jew, but it is thought that inshore spawning migrations followed by offshore movement to aggregation areas is a likely scenario. Again this is very similar to the migratory movement of southern mulloway.

Black jew are opportunistic feeders with prawns and small fish comprising a significant portion of their diet.

Threats
Given that black jew tend to aggregate in the same locations on a regular basis, the main threat to this species in the future, from both recreational and commercial fishers, is most likely to be over-exploitation and incidental mortalities resulting from barotraumas.

In the NT black jewfish landed from less than 10 metres of water showed few signs of barotrauma and were likely to survive if released. Forty-six percent of black jewfish landed from both 10-15 metres and 100 per cent in 15-20 metres had injuries that rendered them unlikely to survive. These results are very similar to those found with mulloway.

It is worth noting that it has been shown in the Northern Territory that black jew are more likely to survive when caught in shallow water using circle hooks and a release weight to get the fish quickly back down to depth.

Tackle and bait
Generally speaking an angler must match their tackle to the specific habitat where black jew are located. If hooked over, or alongside, structure such as offshore reefs, bommies, wrecks and shipping pylons (such as in Port Hedland Harbour), at least 15-25kg braid is recommended joined to a 30-45kg mono leader. Abrasion-resistant leader is highly recommended in this instance.

Rod and reel combinations should obviously be suited to this tackle. Heavy baitcasters and medium/heavy spin gear are suitable. Many anglers often lock drags when tackling black jews in tight situations, so a quality, robust drag system is essential. Anglers are also known to employ heavy handlines and gloves to land black jews.

In some situations anglers can encounter black jew in sandy holes, or along shale and rock ridges in northern estuaries. Lighter tackle can be employed in these situations. However, line capacity is often stretched as large black jew will run fair distances on lighter drag settings. An angler’s best opportunity of landing a jew around structure with light tackle is to not apply heavy pressure in the initial stages of a fight. A black jew can run out away from structure on a light drag setting and an angler can then position a boat accordingly to fight the fish away from trouble. It is a sad fact that many black jew are lost in the first few seconds after hookup!

Rigs vary depending on tidal currents and depth. Many anglers utilise simple rigs such as a running sinker down to an 8/0 hook. The hook used must be strong and able to withstand the pressure exerted by locked drags holding large fish struggling to find structure. Circle hooks are becoming increasingly popular as they allow improved release survival in shallow water and have the tendency to provide a stronger connection when hooked up to a rampaging fish.

A simple running sinker rig is preferred as the weight of the sinker does not dissuade a fish that is running with the bait. When tidal currents are strong a larger snapper sinker may be required. Again, this should be rigged as a running sinker to allow movement of line.

Whole large mullet or whiting, or fillets of either, are the best baits, but any fresh whole or cut fish bait will work, as will whole squid. King prawns are deadly. Live baits can also be used, but they are far too often magnets for sharks. They can also be eager lure takers and black jew are often encountered when barra fishing. Any barra lure will work. Big soft plastics work well too. One of the best black jew lures is the big Prawnstar.

Boat fishing success rates, in difficult underwater terrain, can be greatly improved by dropping the anchor line on a float and chasing the fish.

Fishing methods
Near-shore structure (within 3km) is far more reliable than farther offshore for targeting jew. Renowned spots for them on the West Coast include Port Hedland Harbour, Cape Keraudren and Roebuck Bay.

Black jew frequently bite best around the changes of tide. Generally a rising tide would also be considered better than a falling one. The most important task is to locate the structure where fish are likely to be stationed. The choice is then to wait for the fish to come on the bite, or move between locations to find feeding fish.

Generally drifting over structure and bouncing jigs/plastics close to the bottom is effective. Given the strength of northern tides boat drift speeds are mostly too fast so anchoring over a specific structure can still allow success with jigs.

Trolling can also account for good fish in northern creeks and rivers. Generally mulloway will be concentrated in deep holes that hold at least two metres of water at low tide. In other creeks that drain out on low tide they move in and out spasmodically and are difficult to target with reliability.

As they are a schooling fish black jew can often “bite” intensely in a relatively short period of time. If multiple anglers are on the boat there is often a rapid rate of hookups. The school can also move on as quickly as it arrives and dropped fish do at times appear to spook the rest of a school.

References: Compiled with the assistance of Tim Gray and Rob Vaughan

Assessment of the implications of target fishing on black jewfish (Protonibea diacanthus) aggregations in the Northern Territory (Fishery Report No. 91) by Michael Phelan

Fishbase website  www.fishbase.org