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Southern Garfish has a wide distribution around Australia. There are eight stocks or management units across WA, SA, TAS and VIC. Four stocks are sustainable, one is depleted and three are recovering.

Southern Garfish has a wide distribution in Australia, extending from Lancelin in Western Australia, along the southern coast of mainland Australia and up the east coast to Eden in southern New South Wales, as well as the surrounding waters of Tasmania [Gomon et al. 2008].

There has been no research into the stock structure of Western Australian populations of Southern Garfish. However, given the limited dispersal typically displayed by Southern Garfish, and the large spatial separation between the west and south coasts of Western Australia, it is highly likely that the west and south coast support separate biological stocks of this species [Ye et al. 2002; Steer et al. 2009].

In Victoria, there has been no research into the stock structure for populations of Southern Garfish and they are assumed to constitute a single jurisdictional stock.

In Tasmania, differences in size and age composition between the north coast and the east coast indicate that there may be multiple biological stocks; however, no firm evidence exists at present, and current stock assessments assume a single state-wide biological stock [Moore et al. 2018].

A multidisciplinary otolith-based study (otolith chemistry and morphometrics) identified at least five biological stocks in South Australia: West Coast, Northern Spencer Gulf, Southern Spencer Gulf, Northern Gulf St. Vincent and Southern Gulf St. Vincent [Steer et al. 2009]. Given the level of spatial separation of Southern Garfish observed between the gulfs, it was assumed that Southern Garfish from the south-east also comprised a separate biological stock. However, following a major reform of South Australia's Marine Scalefish Fishery in 2021 [Smart et al. 2022a], individual transferable quota arrangements and spatial scale of assessment for some key species(including Southern Garfish) were implemented at the spatial scale of four management zones: West Coast, Spencer Gulf, Gulf St Vincent/Kangaroo Island and South East.

Here, assessment of stock status is presented at the biological stock level for Western Australia (West Coast and South Coast), management unit level for South Australia (West Coast, Spencer Gulf, Gulf St Vincent/Kangaroo Island and South East) and at the jurisdictional level for Tasmania and Victoria.

Western Australia South Coast

Throughout the south coast of WA, annual catches have fluctuated between 5 to 35 t, with the highest catch recorded for the early 1990’s and lowest catches recorded around 2000 and consistently since 2017. Overall, there has been a slight downward trend in catch in recent decades. Results from periodic surveys of boat-based recreational fishing on the South Coast of WA indicate low catch levels by these fishers. There is limited available information on shore-based catches of Southern Garfish for this region.

A study by Jones et al. [2021] provided estimates of biological parameters and total mortality for Southern Garfish, based on catch curve analysis applied to age composition data collected in 1998–99 at multiple sites along the south coast (Oyster Harbour, Princess Royal Harbour, Wilson Inlet and Peaceful Bay). That analysis yielded a total mortality estimate of 0.90 y^-1, which was the lowest value for this species across all sampling regions in South Australia, Victoria and Western Australia. The maximum age for this species was assumed to be 10 years, as this was the oldest age recorded by Jones et al. [2002] for garfish across all regions and it occurred on the south coast of WA. This translates to a value of 0.42 y^-1 for natural mortality (M) using the approach of Dureuil & Froese [2021], with 1.5% survival of fish to the maximum age (10 y) in an unfished population. This associated estimate of fishing mortality (F= 0.48 y^-1) is just above M, which is indicative of a moderate level of exploitation for the population at the time of sampling in that study.

Applying the above mortality values and biological parameters estimated by Jones et al. [2002] for Southern Garfish on the South Coast of WA in a traditional per recruit analysis yields an estimate for spawning potential ratio (SPR) of 0.36, which is between the threshold (0.3) and target (0.4) levels. Using an extended form of per recruit analysis, incorporating a stock-recruitment function to allow for potential effects of fishing on recruitment, yields an estimate of relative female spawning biomass of 0.3, which is at the threshold level. The above results from per recruit analyses indicate that in the late 1990s, after the peak of commercial fishing, this species was not over-exploited. Given that since this time commercial catch levels have been low relative to their peak in the early 1990s, and that recreational catches are likely much lower than commercial catches, the current population is likely to be sustainable.

Southern Garfish is a relatively short-lived species and attains maturity at a relatively young age (i.e., the population is expected to be relatively productive). Further, almost all the Southern Garfish catch in Western Australia consists of mature fish [Jones et al. 2002; Smith et al. 2017]. Commercial effort directed towards species within Wilson Inlet, where most of the commercial catch of this species is taken, fluctuates considerably from year-to-year, being impacted by the availability of more valuable marine species, which, in turn is impacted by bar opening timing, duration and frequency. The nature of this fishery, therefore, offers a level of protection to garfish through periods of reduced targeting.

The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Furthermore, the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired. 

On the basis of the evidence provided above, Western Australia South Coast stock is classified as a sustainable stock.

Western Australia West Coast

Until the closure of Perth metropolitan waters (i.e. between 31-33º south) to commercial and recreational fishing for southern garfish in 2017, the majority of the catch of this species in the West Coast Bioregion was taken from Cockburn Sound. The most recent assessment of the adult spawning stock in Cockburn Sound was completed in 2017 [Smith et al 2017], following the Western Australian Department of Primary Industries and Regional Development’s risk-based Weight of Evidence approach. Using this approach, the assessment considered the vulnerability of this species to fishing given its biological characteristics, catch and catch per unit effort (CPUE) trends, age and length composition data, catch curve estimates of fishing mortality, and yield-per-recruit (YPR) and spawning potential ratio (SPR) estimates, with the latter calculated based on spawning biomass per recruit and also eggs per recruit. The assessment assigned Southern Garfish in Cockburn Sound a high risk to sustainability at the catch and effort levels experienced by the stock post-2005 [Smith et al 2017]. The decline in stock status was attributed to both environmental drivers (e.g., marine heatwave events) and overfishing. Concerns over the risk to sustainability resulted in the above-mentioned prohibition on catching garfish in Perth Metropolitan waters from 2017.

Anecdotally, there are increasing reports, from commercial and recreational fishers catching other species, of garfish occurring in abundance within the area of the closure. Based on a Productivity Susceptibility Analysis (PSA), the southern garfish stock in Cockburn Sound is considered a low relative risk due to fish maturing at approximately 1 year and immature fish being rarely caught by recreational or commercial fishers. There has been no reported catch by commercial fishers, and only a small amount of catch is recorded as being taken by recreational fishers (despite the closure). Therefore, the closure is likely to have reduced fishing mortality to near zero since 2017, and a substantial increase in abundance since 2017 is plausible.

Predicted values for MSY derived from a data-limited Catch-MSY analysis were between 18 and 20 t, depending on the prior ranges specified for final depletion. If assuming zero catch since 2017, this Catch-MSY analysis predicts a substantial increase in stock biomass since that year. It is acknowledged, however, that together with several strong model input assumptions, this Catch-MSY method assumes a constant carrying capacity which may not be plausible for Cockburn Sound due to the known substantial environmental changes that have occurred in this embayment, including multi-decadal declines in seagrass abundance. Furthermore, declines in environmental productivity (combined with historical fishing pressure) in Cockburn Sound have been linked to the decline and subsequent closure of a blue swimmer crab fishery in Cockburn Sound (Marks et al. 2021).

The above evidence indicates that prior to 2017 the stock was depleted. However, as Perth metropolitan waters have been formally closed to fishing for Southern Garfish since 2017, with negligible catches taken during this extended period, the very low or negligible fishing mortality resulting from this closure is expected to have allowed stock recovery. 

On the basis of the evidence provided above, the Western Australia West Coast biological stock is classified as a recovering stock.

Southern Garfish biology [Ye et al. 2002; Smith et al. 2017]

Victoria – Indigenous (Management Methods). A person who identifies as Aboriginal or Torres Strait Islander is exempt from the need to obtain a Victorian recreational fishing licence, provided they comply with all other rules that apply to recreational fishers, including rules on equipment, catch limits, size limits and restricted areas. Traditional (non-commercial) fishing activities that are carried out by members of a traditional owner group entity under an agreement pursuant to Victoria’s Traditional Owner Settlement Act 2010 are also exempt from the need to hold a recreational fishing licence, subject to any conditions outlined in the agreement. Native title holders are also exempt from the need to obtain a recreational fishinglicence under the provisions of the Commonwealth’s Native Title Act 1993.

South Australia – Commercial (Catch). Data for the Northern Zone Rock Lobster Fishery (South Australia) and the Southern Zone Rock Lobster Fishery (South Australia) have been combined because of confidentiality requirements.

Tasmania – Recreational (Management Methods). In Tasmania, a recreational licence is required for fishers using dropline or longline gear, along with nets, such as gillnet or beach seine.

Tasmania – Indigenous (Management Methods). In Tasmania, Indigenous people engaged in fishing activities in marine waters are exempt from holding recreational fishing licences but must comply with all other fisheries rules as if they were licensed. Additionally, recreational bag and possession limits also apply. If using pots, rings, set lines or gillnets, aborigines must obtain a unique identifying code (UIC). The policy document Recognition of Aboriginal Fishing Activities for issuing a Unique Identifying Code (UIC) to a person for Aboriginal Fishing activity explains the steps to take in making an application for a UIC.

Western Australia – Recreational (catch). Current shore-based recreational catch and effort in Western Australia is unknown. State-wide surveys of boat-based fishing are conducted regularly, most recently in 2020–21 [Ryan et al. 2022].

Commercial catch of Southern Garfish - note confidential catch not shown

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