The inconvenient truth about unsustainable gillnetting in the Great Barrier Reef Marine Park.


This is article 2 of a series of 4 articles based on NSF reports (available here) written By David Cook for Lee Brake, editor of NQ Fish and Boat, based out of MacKay, in order to spread the word in easy-to-read, everyday speak in their monthly publication. A word document with scans of the first three articles as printed is available here. .

king salmon with roeLast article I asked the question “Is our inshore fishery sustainable?” I was referring in particular to the east coast commercial gillnet fishery. Under present regulations and management, and given the failing health of our coastal ecosystems, I concluded that it was not. I also noted that findings from recent studies suggest that gillnetting risks causing the further decline of at least some of our best-known inshore fish, possibly to the point of local extinction in some areas. These conclusions do not imply that Queensland’s gillnetters themselves are at fault in any way. Rather if there is any fault to assign, it lies squarely with the out-dated regulation and management of the fishery. Once we put some important facts on the table it is fairly obvious that some big changes are necessary before the gillnet fishery could ever be properly certified as truly ‘sustainable’. This month I want to take a closer look at a number of issues on which I base these conclusions.

I trust that gillnetters will recognize that most of these refer to matters beyond their control. Sustainable Fisheries As a bit of a teaser I did not define what I meant by ‘sustainable fisheries’ last month. If you look up the term you will find a number of definitions. For our purposes let’s not get too bogged down with all the different definitions, but let’s cut to the chase. blue samon with eaten longtom

Basically a sustainable fishery is one where the numbers and sizes of the fish involved do not decline significantly over the years as a result of the fishing activities, the ecosystem and their components are not damaged because of the fishing, and it causes no other adverse impacts on current or future generations. Sure, there are still some shortcomings with this description, but I trust you get the picture. I suggest all the issues I raise below do need to be adequately addressed by the authorities before the east coast gillnet fishery could be classified as sustainable by any competent, independent and non-government authority.


Who fishes where? One of the most outstanding issues placing even the best-intentioned gillnetters between a rock and a hard place is that gillnetters can set their nets anywhere along the East Coast open to general gillnet fishing. This means that any attempt by local netters to look after local resources is pointless when out-of-towners can come in and take the lot. As authorities have no way of managing who fishes where and how much, current regulations reward a "take it before someone else does" mentality. You can argue that this also may be the case when a number of local netters compete with each other whilst fishing the same area. Biology The authorities knew nothing about some critical aspects of the biology of inshore fish species when the current fisheries regulations were developed. Queenfish with roe

Recent findings regarding the life cycles and movements of threadfin salmon and grey mackerel, for example, require a review of the regulations and the necessary changes made. Whilst there are seasonal fishing closures to protect spawning reef fish, there are no closures, other than for barramundi, to protect other inshore species from gillnets whilst spawning. I personally cut open all four species pictured here and found them all to have developing roe, indicating spawning would have been outside of the barra closure. As far as is known, each of our larger inshore species comes together to spawn in schools or ‘runs’ at predictable sites and times in inshore waters where they can easily be netted. It is during these times that they are at the greatest risk of being overfished by gillnets. After spawning, the schools may break up as individuals or smaller groups and spread out over much larger areas and so are more difficult to overfish.

There is nothing to stop all the gillnetters in Queensland turning up to fish a single spawning run for, say blue threadfin, and netting them to oblivion before they spawn. That sadly is not even half the problem. To complicate matters, species such as grey mackerel and threadfin have recently been shown to live in separate (non-mixing) localised populations occurring at intervals along the East Coast. As an example of how this comes about, neither king nor blue salmon appear to venture into clear water or over ‘clean’ sand or rock. This restricts their wanderings to particular estuary systems and adjacent muddy waters separated from other estuary systems by ‘clean’ sandy or rocky seabed.

Genetic studies have shown populations from separate estuary systems have been isolated from each other for probably thousands of years, indicating there is not even transfer of eggs or larval fish between them. For all we know, the same may be true for other inshore species such as grunter, tripletail, queenfish, fingermark and permit, none of which have received the same level of study. If populations on spawning runs are ‘netted-out’ before they have had the chance to drop their eggs, their numbers will not be topped-up by immigration from other areas.

Grey Makerel with roeThis may lead to long-term local depletion and even extinction of that local population. The collapse of the Bowen grey mackerel fishery on Reyward’s Reef in the 1970’s may well be the first recorded case of the commercial extinction of one such localised population. The apparent partial-collapse of the Douglas Region grey mackerel 2008 – 2010 could have been total collapse if the offshore netters had not heeded the local public outcry and left the fishery alone after the 2007 season.

The complication of fish stocks being made up of different, non-mixing and undefined regional populations turns into a Fisheries manager’s nightmare when we learn that most individuals of key species such as barramundi and king threadfin do not become female until over 80 cm in length at over seven years of age. The minimum legal sizes for these species, as well as for e.g. grey mackerel, are well below the size at first spawning – a big no-no in any fishery hoping to be described as sustainable. It doesn’t stop there. As we all know, different species mature at different sizes. Four inch gillnets are allowed in the fishery and are also used illegally. These can be expected to kill countless numbers of undersized larger species. Undersize threadfin, for example, die quickly in gillnets, usually before they can be released.

I’ll never forget the day my family and I meshed about 200 fingerling queenfish when drag netting for bait – all died during or after their release. I’ve never used a drag net since. As immatures of other larger species are also bound to die in quantities in both commercial bait nets and recreational drag nets, it is hardly surprising that many of our inshore species are in decline, even before we consider influences of changing environmental and ecosystem conditions. Part-timers As part-time commercial fishers may earn most of their income from other sources they can subsidise their fishing to a high risk level over the long-term. Cashed up from other work, they can afford to keep on netting when catches have fallen so low as to make it pointless for fulltime fishers to continue. Some part-time fishers have also apparently earned a reputation for only ‘pulse fishing’ when the resource is most easily caught in good numbers, e.g. at the start of the barramundi season, when the stock may still be gathered near the mouths of estuaries, or when other fish are on spawning runs and therefore most vulnerable to overfishing.

Part-time gillnetters therefore also risk spoiling the fishery for full time fishers by taking the cream that would otherwise keep fulltime fishers going throughout the season, flooding the market with a glut of fish at peak seasons, resulting in reduced prices at such times. Size of the fishery In north Queensland our rivers are short and catchments small in comparison to the size of Australia simply because the mountains come fairly close to the coast in these parts. This translates into smaller nursery areas for juvenile fish and fewer large inshore fish in and around our estuaries in comparison to the much longer rivers, larger catchments and larger estuaries along much of Asia’s more nutrient rich coastal waters. Whilst there may be an opportunity for a well-regulated, small-scale gillnet fishery in NQ, our inshore waters certainly do not appear to have the potential to sustain a medium-sized or industrial level gillnet fishery involving roving gillnetters moving up and down the East Coast in addition to the local netters.

Way forward:

;As you probably know, Fisheries Queensland is carrying out a buyback of gillnet endorsements and fishing licences with the aim of reducing gillnetting by around 50%. Even if this target is achieved, I doubt whether this fishery could be certified as genuinely sustainable until the fisheries regulations are amended to address the issues I have raised here.

In next month’s NQ Fish & Boat I hope to discuss what some of these changes should be and how they could benefit both those gillnetters who remain in the fishery after the buyback and also all you recreational fishers out there.

Meanwhile if you have any problems with any of the above, do feel free to drop me an email. David Cook davecookATbigpondDOTcom

Read article 3 of 4 here

Captions: 1 A king threadfin netted 2 February 2013 on the Daintree coast, total length 82.5 cm, with ripening roe 12 cm in length. Individuals of this size are now a rare catch in these waters. 2 Blue threadfin netted 4 March 2013, Daintree coast, total length 70.5 cm, with ripening roe. I opened the fish myself and the partly-digested 50 cm longtom was in the stomach, folded in four sections. Must have been some struggle to get that down! 3 Queenfish caught 21 September 2012, Daintree coast, total length 116 cm with large roe 24 cm across. Schools of queenies are now much smaller and less common than 10 years ago. 4 Grey mackerel caught 10 September 2011, Daintree coast, total length 97.5 cm with very large roe 26 cm in length, 369 gm in weight. This fish could probably have spawned within a week.