Western Australia Dhufish Management

The dhufish (Glaucosoma hebraicum) is a demersal fish species endemic to Western Australia. They populate the coastal region, about 20-50 meters deep, from Shark Bay to the Recherche Archipelago but are most abundant between Kalbarri and Augusta (West Coast Bioregion, 2005, p.2). Because of their superb taste and large size, the dhufish is a prized catch for recreational and commercial fishers who have elevated the species to its current iconic status.

The maximum lifep of the dhufish is estimated at 40 years. Maximum length can reach one meter or more and weight can exceed 25 kilograms. They grow relatively fast before they reach 12 years old afterwhich growth rates slow down noticeably. The minimum legal size of dhufish is 500mm which they reach within 6-7 years (FMP No. 225, 2007, p.23)

Female dhufish are ready to spawn once they are 3 or 4 years old, having reached an average length of 33 centimeters (Factsheet 3, 2007). However, female dhufish spawn the most eggs when they are older. The spawning season occurs between November to March when the waters get warm but is at its peak from December to March. Here, dhufish aggregations can be spotted in the waters.

Dhufish Habitat and Current Status

            The dhufish habitat is in the waters of the West Coast bioregion considered to be a temperate oceanic zone (West Coast Bioregion, 2005, p.2). During their early life stages, dhufish occupy the hard-bottom seabed where there are plenty of sponges but as they mature, they move to low-lying reefs and then to major reefs where they are observed to be sedentary (Hesp, Potter and Hall as cited in Pagano and Fuller, 2006, p.7). This environment has been relatively invariable so that drastic changes would cause severe adaptation problems for dhufish.

Current research reveals that the temperature of ocean waters and food sufficiency are crucial factors that affect the percentage of young dhufish survival or recruitment (Factsheet 3, 2007). When conditions in the environment are at its best, dhufish recruitment is also at its highest resulting in a remarkable increase in fish population described as the “boom years”.

During the past 2 decades however, boom years have been minimal. This phenomenon compounded by the increase in fishing activity due to population and tourism factors and the technological advances in fishing methods have worked together to severely reduce the local dhufish stock (Factsheet 3, 2007).

The decrease in in-shore dhufish populations is especially marked in the metropolitan  coasts (i.e. Lancelin to Mandurah) where fishers now have to go farther out to sea in order to land fish. The concern over the depletion of dhufish stock grew within the past 10 years leading to the conduct of various researches and management efforts. Currently, the dhufish is classified by the Fisheries Board as Category One or highest risk (Recreational Fishing Guide, 2007).

The natural mortality rate of 10% per annum has been exceeded by the fishing mortality rate of 11% per annum, objectively indicating that the dhufish are already being overexploited (Gaughan as cited in Pagano and Fuller, 2006, p.13). Because fishing mortality is based on annual fish catch, it does not even factor in the mortality due to release. A study has shown that most dhufish released die from deephooking or barotrauma (Gaughan and St. John, as cited in Pagano and Fuller, 2006, p.17). Fishing mortality has to be decreased by 50% in order to assure dhufish sustainability (FMP No. 225, 2007, p.6)

Factors Affecting Dhufish Stock

Fishing for recreation is part of the average Australian’s lifetime passions. Aside from the benefits of sport, Cribb (as cited in Pagano and Fuller, 2006) elucidates that “there is a strong cultural element of communal food gathering and sharing in Western Australia, with many recreational fishers specifically seeking fish for the consumption, rather than for non-consumptive sport” (p.34). Currently, it ranks fifth among 50 other recreational activities in terms of number of individuals participating.

Recreational fishing, specifically angling, is practiced in areas where human populations are concentrated and mainly target inshore waters. Of the more than 2 million Western Australia population today, 34% engage in it representing a 7% increase since 1987 (Recfishwest, 2008). Frequency has increased to 311,400 fishing days a year with a 200% increase in the number of anglers per day within the past decade (Cribb as cited in Pagano and Fuller, 2006, p.38).

Urbanization as well as land and sea transport infrastructure has made much of the coasts and near-shore waters accessible. At present, dhufish fishing has become more extensive with the prevalent use of boats that can go as far out as 50 miles. In 2006, there were 81,417 registered recreational fishing boats and 138 charter fishing boats for tours, with majority in the Metropolitan Area (FMP No. 225, 2007, p. 33).

The promotion of recreational fishing in the media and internet, as well as the landing of dhufish as the ultimate symbol of fishing success, has also further increased the interest of people in dhufish fishing. Anglers traditionally used two lines and simply fish by hand but today, there have also been marked improvements in angling gear. The use of Global Positioning Systems and acoustic technology has also gained popularity among fishers and has made recreational fishing activities more efficient and productive.

Modern commercial fishing now also employ DPS fishing machines and methods such as trawling and dredging can severely disrupt the food chain in the marine ecosystem and cause damage which affects the well-being of its species and reduces the availability of marine resources for human consumption (Cribb as cited in Pagano and Fuller, 2006, p.29).

Of the estimated 409 tonnes of dhufish caught in the past year, recreational fishing accounted for 45%, commercial fishing landed 44% while 5% was from chartered fishers (FMP No. 225, 2007, p.12-17). Recreational fishing provides $570M to the Western Australia economy annually (Recreational Fishing Guide, 2007, p.2).

Commercial fishing or wetlining is regarded today as an expensive economic endeavor with its reliance on costly equipment which greatly increases overhead expenses. Coupled with the lower catch rate in recent years and a steady dhufish price in the market, dhufish catch restrictions on one hand and the need to increase fish catch on the other poses a dilemma for commercial fishers (Shinnick as cited in Pagano and Fuller, 2006, p.24).

Charter boat fishing involves recreational fishers/tourists who go fishing together and share the expenses of the trip. In this way, they can fish in deeper waters and minimize cost. The dream catch of charter boat fishers is the prized dhufish and although they tend to land other species instead, it does not translate to a fishing experience that is worth their money. As such, charter boat operators are pressured to enable their customers to land their dhufish (Beva as cited in Pagano and Fuller, 2006, p.29).

Dhufish Management

Much of management relies on accurate information and research and an effective conceptual framework. Historically, much of dhufish fishing regulation has targeted commercial fishing because of the view that recreational fishing does not impact significantly on fish stock. Hence, varying bag and other restrictions were enforced on wetliners while anglers were generally unrestricted.

However, as the problem of dhufish overfishing became more pronounced in the mid 1990’s, the state began to consider the range of management practices that can be adopted for mitigation. This included whether to target dhufish as a specific species and focus on its habitat (biological conservation) or adopt a broader ecosystem-based management (Cribb as cited in Pagano and Fuller, 2008, p.34)

Interest in dhufish research by academic institutions, the fishing industry, recreational groups and the Department of Fisheries has been sparked within the past decade encouraged with significant funding from stake-holder sectors and the state. The current research available still poses a lot of data gaps and with regards to statistical information, there is a general clamor for a more accurate method of data generation, particularly with catch data and release data (McGlennon, 2004).

Deeper research enables the formulation of appropriate management strategies. However, the urgency of the problem forced policy makers to rely on the available preliminary information and research. This led to extensive stakeholders’ consultations geared towards developing a management plan acceptable to all and later, to legislations as can be evidenced in the latest Western Australia fishing guidelines and restrictions.

Research

Members of the Western Australia fishing industry have initiated efforts in raising dhufish in attempts to sustain or increase stock for current and future use but were highly unsuccessful. In 1995, the Aquaculture Development Unit of Challenger TAFE conducted a research on dhufish breeding and declared that although possible, it was not feasible commercially (Jenkins as cited in Fuller and Pagano, 2006, p.5-6). This was because some biological characteristics of the dhufish hinder their unproblematic adaptation to aquaculture environments.

Release methods pertain to the return of live undersize dhufish into the water. Because of the high mortality of released dhufish due to barotrauma, the Australian National Sportfishing Association (ANSA), with support from the Recfishwest and the Australian Anglers Association (AAA), developed the release weight method to reduce its incidence (Recfishwest, 2008).

Research also showed that the lower the depth of water in which dhufish is caught, the more likely it would suffer barotrauma. The speed of bringing in the fish also determines its probability to die of it so that it is being advocated that fishers should bring in their dhufish more slowly, handle it with wet hands and support its belly during handling.

Further and continuous research needs to be done on the life cycle of the dhufish, its behaviors, the crucial factors in its habitat as well as exploring and developing methods of conservation such as stock enhancement (FMP No. 176, 2004). With regards to surveys for monitoring stock, mortality, etc. similar surveys with minimal probabilities for bias should be done on a regular basis.

Legislation

Setting bag limits and other restrictions in recreational Dhufish fishing is an attempt to redefine its cultural norms as a social activity. This means changing people’s perceptions regarding their rights to fish and established measures of fishing success towards responsible fishing. This also means reconciling the welfare of the fish with current and long term human benefits.

Major change in practice needs education and enforcement before it becomes the norm. The consultation process was instrumental in gaining the cooperation of all sectors involved. The partnerships among stakeholders should be maintained in order to make dhufish management participatory and with less intensive state regulatory measures.

The new fishing guidelines are intended to permit the dhufish to breed a few years after sexual maturity before being caught, allow them to spawn during the whole duration of the spawning season through imposing closed seasons (Recreational Fishing Guide, 2007). It also intended to lower fishing mortality through restrictions in fishing gear and the number of fish that can be landed by individuals as well as prescribe appropriate release methods and appropriate fishing areas (Hesp, Potter and Hall, p.8 and Recreational Fishing Guide, 2007).

Community Education

The advocacy for dhufish management should be widely supported and sustained in the coming years. Aside from research and legislation, community education is also very important. The commercial, charter and recreational fishing sectors have a lot to contribute in this aspect. Fishing and recreational associations and clubs should be involved in order to reach out to greater numbers of operators, fishers, tourists and other individuals and facilitate both research and legislation. Public education and information campaigns through the media should also be maximized including the internet as equally important channels.

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Western Australia Dhufish Management. (2016, Aug 11). Retrieved from https://phdessay.com/western-australia-dhufish-management/

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