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Marine ecology experts are calling for an urgent change to global fisheries management following the publication of data showing an unprecedented decline in fish populations in Australian waters.

The researchers conclude that fishery management urgently needs to become more precautionary, and to take better account of the ecological issues and uncertainties when setting allowable catch levels in commercial and recreational fisheries.

Lead author, UTas Professor Graham Edgar, said that the use of underwater surveys conducted as part of the Reef Life Survey, a global citizen science program, combined with research diver surveys, allowed the first fishery-independent assessment of the size and abundance of coastal fish species around the Australian continent.

“We found consistent population declines amongst many popular commercial and recreational fishes, including in marine parks that allowed limited fishing, while numbers increased within no-fishing reserves,” he said.

Professor Edgar and co-author UTS Adjunct Professor Trevor Ward noted that Australia and other countries will not be able to meet international agreements on marine ecosystems and fisheries without major changes in marine ecosystem management, including the management of commercial fisheries.

“Effective recovery of fish populations, so that catch can be doubled from the present very low levels, cannot occur without major change to business as usual,” Professor Edgar said.

The authors say that marine reserves are a well understood management option that is available ‘off the shelf’, and offers the least-cost high-impact intervention with benefits to both ecosystems and to fisheries.

“No-fishing marine reserves are well known to be efficient and effective mechanisms for the ecological protection of fish populations,” Professor Ward said.

“There is little doubt that in Australian waters, with proper design and placement, marine reserves would assist fish population recovery.

“Eventually this would lead to increased catches for all fishers,” Professor Ward said.

Key points from the study include:

Effective marine management is needed now, more critically than ever. Coastal and offshore ecosystems are changing rapidly (McCauley et al., 2015), at a time when the history of fisheries management includes some successes and some highly publicized failures (Beddington, Agnew, & Clark, 2007; Pinsky, Jensen, Ricard, & Palumbi, 2011; Worm et al., 2009). The global wild fish catch peaked in the 1990s and is now declining (Pauly & Zeller, 2016; Watson & Tidd, 2018). Addressing these issues potentially involves both improved fisheries management and the application of ‘no‐take’ marine protected areas (MPAs), i.e. ‘marine reserves’ (Costello et al., 2012; Edgar et al., 2014; Hilborn, 2016; Pendleton et al., in press). A single marine reserve can provide insurance against population declines for hundreds of species and improved fisheries outcomes, as long as it is well designed and regulated (Edgar et al., 2014; Ward, 2004). Yet despite the public desire and expectation for a greatly expanded and effective MPA network (Hawkins et al., 2016), marine reserves presently cover less than 2% of global marine waters (Boonzaier & Pauly, 2016).

Here, decadal time series were used to estimate the net benefit of marine reserves in enhancing the biomass of large reef fishes, relative to both marine parks with limited fishing permitted and to open‐access waters where normal fisheries regulations apply. We integrate outputs from three broad‐scale reef fish monitoring programmes (Stuart‐Smith et al., 2017), which together span temperate and tropical waters around Australia.

Outcomes of field monitoring are compared with trends in fishery catches to test claims that Australian fisheries are managed sustainably using ecosystem‐based approaches (Fletcher, 2006). Australia's fisheries encompass arguably the most complex and expensive management systems worldwide on a per unit catch‐weight basis. Management practices ranked second for sustainability in a global marine performance assessment of 53 countries (Alder et al., 2010), with frequent praise from fisheries experts worldwide (e.g. Hilborn, 2016). Australia's approach to sustainability embraces the ratification of the Convention on Biological Diversity (CBD), which includes the obligation (Aichi Target 6) that ‘By 2020, all fish and invertebrate stocks and aquatic plants are managed and harvested sustainably, legally and applying ecosystem based approaches, so that overfishing is avoided, recovery plans and measures are in place for all depleted species, fisheries have no significant adverse impacts on threatened species and vulnerable ecosystems, and the impacts of fisheries on stocks, species and ecosystems are within safe ecological limits’ (https://www.cbd.int/sp/targets/rationale/target‐6/). Given that Australia rates higher for fisheries sustainability than nearly all other CBD parties (which include all UN members other than the USA), a necessary condition for the achievement of Aichi Target 6 globally is that Australia's fisheries comply.

Clearly, the extent to which Aichi Target 6 is achieved will be difficult to measure, given an absence of data relating to the ‘safe ecological limit’ aspect of the sustainability for most fisheries. Furthermore, fishery sustainability can only be recognized amongst the small fraction of fisheries that are actively managed. Because of high management costs relative to fishery value, quantitative stock assessments involving population modelling and the collection of life‐history information and fishing effort (including growth, size distribution, and maturity) cover <1% of species (Costello et al., 2012), and very few of these include annual fishery‐independent assessments of population trends (including larval settlement and egg production proxies). Most stock assessments rely solely on trends in catch per unit effort (CPUE) or catch history (representing 52% of the 233 ‘key’ Australian marine stocks reported by Flood et al., 2014).

Based on the latest science for Jack Mackerel (West), the Australian Fisheries Management Authority (AFMA) has increased the annual total allowable catch (TAC) for commercial fishers from 920 tonnes to 4190 tonnes.

AFMA’s CEO, Dr James Findlay, said a new season has kicked off in the Small Pelagic Fishery (SPF) with little change to the TACs for the remaining target species, including Australian Sardine, Blue Mackerel, and Redbait.

“The catch limits for the 2018-19 SPF season take into account the latest scientific research and expert advice to keep the commercial harvest from SPF fish stocks at sustainable levels,” Dr Findlay said.

“Following a review and consultation with industry, stakeholders and the SPF Scientific Panel, the AFMA Commission has approved new fishing methods in the fishery, including the use of jigging and minor line (rod and reel).

“These new methods are conditional on fishers meeting additional requirements, such as having an AFMA Observer on board for the first five trips of the season.

“This season there are also changes to the regional catch limits, which will apply to all SPF vessels to minimise the low risk of localised depletion of fish stocks, which are food sources for commercial and recreational species like tuna and billfish.

“Vessels will still have a catch limit of 2000 tonnes per location over a 30 day period, which if reached, requires them to move on to a new location.”

The Commonwealth SPF supplies domestic and international markets for human consumption, for use as recreational fishing bait, and as fishmeal in the aquaculture industry.

For more information on management of the Small Pelagic Fishery, visit afma.gov.au.

Australia has had tens of thousands of years of fisheries exploitation. That history reveals a staggering natural bounty, which has been alarmingly fragile without proper management. The current debate over the federal government’s new draft marine park plans is the latest chapter of this story.

Early accounts described what we can only read today as some sort of fishing Eden. The sea floor off the west coast of Tasmania was carpeted red with crayfish. Extraordinary schools of Australian salmon swelled the beaches of southern Australia — from Albany right around to Port Macquarie. Mountains of mullet migrated annually up the east coast of the continent.

Colonial writers described huge hauls of fish, caught using nets they had brought over on the First Fleet. One catch in 1788 was so large, wrote David Collins, the colony’s newly minted Judge-Advocate, that it actually broke the net. Collins speculated that if the haul had been landed, the entire catch could “have served the settlement [of over 1000] for a day”.

Like colonial fishers on the coast, inland explorers such as John Oxley were struck by the paradox of Australia’s natural world. The land seemed barren and unsuited for pastoralism, he observed in 1817, yet the water teemed with life. In less than an hour, one of his party “caught 18 large fish, one of which was a curiosity from its immense size and the beauty of its colours,” wrote Oxley. “It weighed entire 70 pounds [31kg].”

For Indigenous people, seasonal mobility had both signalled and prescribed the times for fishing and its availability, forming a vital part of their management of local fisheries.

For the Yolngu in Arnhem Land, flowering stringybark trees coincided with the shrinking of waterholes, where fish could be more readily netted and speared, or poisoned. When the D’harawal people of the Shoalhaven region in southern New South Wales saw the golden wattle flowers of the Kai’arrewan (Acacia binervia), they knew the fish would be running in the rivers and prawns would be schooling in estuarine shallows.

In Queensland, the movement and population of particular fish species had their own corresponding sign on land. The extent of the annual sea mullet run in the cool winter months could apparently be predicted by the numbers of rainbow lorikeets in late autumn. If black magpies were scarce in winter, numbers of luderick would also be low. When the bush was ablaze with the fragrant sunny blooms of coastal wattle in early spring, surging schools of tailor could be expected just offshore.

A diversity of Indigenous fishing practices developed to capitalise on this. In the Gadigal nation (where Sydney is situated), Eora fisherwomen hand-lined for snapper, dory and mullet. At the end of their lines, elegant fishhooks made from carved abalone or turban shells were dropped over the side of their canoes.

These canoes, known as nowies, were “nothing more than a large piece of bark tied up at both ends with vines”, described the British officer Watkin Tench. Despite their apparent flimsiness, the fisherwomen were master skippers, paddling across the bays and offshore, waves slapping at the sides of their precarious vessels.

When the water was calm and clear enough, Aboriginal men around Sydney Harbour and Botany Bay were frequently seen lying across their nowies, faces fully submerged, peering through the cool blue with a spear at the ready. They “do this with such certainty,” wrote John Clark in 1813, that they “rarely miss their aim”.

Yet the growth of stationary colonial settlements soon saw those fisheries put under enormous pressure.

By the mid-1800s, local fisheries near rapidly-growing cities such as Port Jackson and Botany Bay were already seeing the effects of over-fishing. Practices such as “stalling” netted off entire tidal flats at high tide, and trapped everything behind a thin layer of fine mesh when the water retreated. Fishers picked out the larger fish such as bream, whiting and flathead for market, but piles of small fish were simply left to rot.

While the “net of the fishermen gradually increased in length”, noted Alexander Oliver, who was appointed to the 1880 Commission of Inquiry into the NSW fisheries, the “meshes decreased in width, so that nothing escaped, and bushels upon bushels of small fry — the young of the very best fishes — were left on the beaches”.

There were calls for greater regulation and fisheries management by the mid-19th century. Fish “are followed up every creek and cranny by their relentless human enemies”, and “perpetually harassed and hunted”, reported the 1880 Commission, which had been convened to investigate the poor state of the local fishing industry. It revealed an anxiety over stocks and sustainability that sounds eerily familiar today.

The fine-line between commercial exploitation and sustainability has been gingerly walked throughout Australia’s fishing history, sometimes catastrophically.

A Catch of Sea Garfish (Hemirhamphus) at Thompson’s Beach*, near Sydney, N.S.W. 1911, plate II in The Future of Commercial Marine Fishing in New South Wales by David George Stead. National Library of Australia

In the late 1920s, tiger flathead stocks south of Sydney completely collapsed - less than a decade after the introduction of ocean trawl fishing. In 1919, takings on the Botany Grounds had totalled 2.3 million tons. In 1928, flattie stocks crashed, and by 1937 only 0.2 million tons were hauled up by the trawling fleet.

That stocks are still only 40% of pre-1915 levels, nearly a century after their initial collapse, shows just how much longer it takes fish populations to recover after plunder.

In the 1970s and 1980s, the same cycle of boom-to-bust played out with southern blue-fin tuna and orange roughy.

In response, marine parks were introduced from the 1980s, as well as national regulations that enforced catch sizes, fishing zones and seasons, and even the mesh size of nets.

Fisheries management have responded to declining stocks by introducing wide-ranging legislation across the recreational and commercial sectors. But they’re in an unenviable position, essentially forced to make laws in response to fishing practices sometimes over a century old (such as the excessive by-catch of trawlers), while simultaneously “balancing” the contemporary demands of conservationists, recreational and commercial fishers.

To be fair, that quest for “balance” isn’t easy. Yet we also know from history that this is a zero-sum game: there are plenty of fish in the sea — until there aren’t.

*Gordons Bay in Sydney is a small sandy beach on the Bondi to Coogee; people still refer to Gordons Bay as Thompsons Bay or “Thommos”.