Gemfish, Don’t Mention the war

Primary Source AFMA, David Lockwood

Fisheries Managers often get hit with examples of mismanagement and complain they never get credit for the multitude of successes. They usually get criticism in the northern hemisphere about tuna and cod overfishing, in Australia its mainly orange roughy and gemfish. In the 1980s, despite obvious concerns these fisheries were overexploited and dying, they were allowed to catastrophically crash. This fishery is now a shadow of its former self even decades later, and rebuilding of the stock is painfully slow. Sure, there were issues with politics and economic pressures, but I don’t buy the argument that this was in the distant past, we are 10 IQ points smarter now, and the world has been reinvented. It is true that most young fisheries managers weren’t even out of their cots when this happened, but like it or not we occasionally need to be reminded about what happens when nothing is done to deal with an obvious problem, and when being in close cooperation with industry and government can lead to interminable delay.

Gemfish are a bottom dwelling fish which inhabit deep water off the New South Wales, Victoria, South Australia and Tasmania. They are generally found in large schools at depths of 100 – 800 metres on the continental shelf and upper slope (maximum recorded depth is 1254 m). They are more generally found in waters about 250 m – 500 m deep. This species is usually caught close to the sea floor but the fish are likely to move into midwater at times. Juveniles are pelagic. The gemfish is a member of the family Gempylidae, which includes the snoek or barracouta. Gemfish are also known as Hake. They grow up to about 1.2 metres in length and 15 kg and live up to 17 years. They are commonly found at 60-90 cm in length and 2-6 kg in weight. Females reach reproductive maturity at 4-6 years, with males reaching maturity at 3-5 years. Mature gemfish aggregate prior to spawning in the eastern stock. This begins with the aggregation of fish north of Bass Strait in autumn, and concludes with fish reaching the spawning grounds off Crowdy Head, NSW, in August. The eggs and pelagic larvae are then carried back down the NSW coast by the Eastern Australian Current. Spawning occurs in summer for the western stock and occurs west of the Great Australian Bight. We don’t know much about that stock. Females produce 1-1.5 million eggs each spawning season depending on their body size.

A large commercial fishery was developed for gemfish off NSW in the 1970s. Catch of eastern gemfish peaked in 1978 at more than 6000 t, then decreased rapidly after about 1987 with declining mean length of fish in the spawning population and reduced catch rates in the winter fishery. In 1988 eastern gemfish became the first species in the South East Fishery to be subject to a Total Allowable Catch (TAC) which was set at 3 000 t. In the early 1990s the spawning stock was also significantly reduced by a series of very poor recruitment cohorts and the TAC was progressively reduced to zero by 1993. The fishery effectively permanently collapsed with trawl catches currently only 100 tonnes or less per year even decades later. Eastern stocks are managed under AFMA’s Eastern Gemfish Stock Rebuilding Strategy. If adopted and it works, it will take another 20 years or so to recover the stock from 14% to 20% of the unfished stock. The ultimate target is 48%, which gives maximum sustainable yield. However, recruitment over the last 25 years has also been weaker compared to the period from the 1970s to 1980s. Recreational and NSW commercial catch also have the potential to impact on recovery times. Estimates of catch from both of these sectors are unreliable and need improvement. The report says that “rebuilding within the target timeframe is unlikely”. Not much of a confidence booster. The NSW Fisheries Scientific Committee (FSC) has made a proposed determination to list the eastern gemfish (Rexea solandri) in the Threatened Species Schedules of the Fisheries Management Act 1994. According to Atlantis models, which take a whole of ecosystem approach including fishing and climate parameters, there is a risk the eastern gemfish will be extinct by 2040.This is bit unclear though.

Twenty years of unrestrained fishing might end up leading to 100 years of repair work, with not many fish landed in the meantime. The ‘black hat’ scenario is permanent extinction, the first for a fertile oceanic species when many argue that it is virtually impossible to make such a fish extinct. It should be noted, that although it is a small catch, we still allow commercial fishing and there is still a recreational bag limit in NSW of 2 fish per day. So much for the brave new world. This is the sad story with eastern gemfish population, but the good news is that western stocks didn’t get the uncontrolled fishing effort of the 70s and 80s and is doing fine.