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Brisbane’s mysterious barra

I WAS moving down to check on the boat, left high and dry by the run out tide, when the sultry midnight air was interrupted by a sizeable commotion to my right. I was taken aback by the ferocity of the surface strike. From 50 metres away it sounded like throwing a small child into the water. Obviously the piscatorial source of the commotion was worth investigating…

I reached into the boat and found a light baitcaster rigged with a soft plastic, and started moving along the shore, casting as I went. Around 10 minutes later the night air was again disturbed by a sizeable surface explosion close in front of me. But a quarter of an hour of repeated casting into the spot using the sub-surface presentation drew a blank. Time to rethink my approach.

I retreated to the boat to see what options were available. A brief torchlit search discovered more plastics and a home made wooden popper. I tied the popper on. Back at the spot a few minutes passed until the fish revealed its position again. Another mullet bit the dust, and 30 seconds later I had a cast. The trajectory of the retrieve was clearly visible on the water surface against the reflection of the city lights, and my accuracy was rewarded with a violent strike that tossed the popper into the air. The short strike was accompanied by a familiar sharp jolt felt up the line through the butt of the rod.

Safe in the knowledge that I now had the right lure, I moved back down the shore to wake up my son Matthew. The tired little boy was hard to rouse, but I lured him back to the spot with a promise that he was about to see something spectacular.

Besides wanting another witness to the nocturnal predatory drama unravelling in front of us, I wanted Matty to see for himself what night fishing with poppers was all about. We had to wait a few minutes until the fish struck again, but in the meantime a few blind casts were made to keep the tired boy occupied. Matty was happy to cast around until the fish revealed its position. The violence of the strike, so close to us in less than 60 cm of water, had the 10 year old spooked by the unseen monster below. He stepped back from the water’s edge and there was no way he would touch the rod from then on, despite my reassurances.

With the feeding location of the fish pinpointed, I cast over the spot. Again I was rewarded with a thundering boof that tossed the popper back into the air, but again the unseen predator missed the hooks. After a couple more missed strikes, I changed the stop start retrieve to a slow crawl and was rewarded with a solid strike that loaded the rod all the way to the butt. The fish immediately got completely out of the water and against the reflected light we saw a sizeable animal tailwalking towards us, but a second later the line went slack as it broke somewhere in the rod guides. A post mortem suggested that slack line from the leap caused a tip wrap which, in the dark, quickly halted proceedings.

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The author looks surprised after catching this 85 cm barra within sight of city lights. Caught on a surface lure after losing a bigger one at the same spot a few weeks before.

Even though the disconnected fish jumped out several more times until the lure was dislodged, there wasn’t enough light to confirm its identity. But it was big, in the 90-100 cm class. In the hour that followed, Matty and I discussed the event with excitement until he succumbed to sleep, while I kept casting until dawn intervened. While these happenings might be considered routine for lucky anglers in our tropical north, we were fishing an urban area less than 50 km from the Brisbane CBD.

The night time fishing bug had bitten again after a decade of kid inflicted absence, and preparations began for round two. There was much speculation regarding the identity of the beast. We regularly get mangrove jack in this area, but the fish was clearly no jack. Threadfin don’t tend to feed on the surface, mulloway don’t jump, and tarpon simply don’t get that big around here.

Could it have been a barra? I’d previously caught one near Brisbane; a 65cm aquarium escapee model that took a jig while fishing for bream under a canal pontoon. I still remember the shocked look on the face of the early morning kayaker who saw me not only catch a barra, but put it back. Despite this fish being in a whole different league altogether, all we had were memories. There was not one shred of concrete proof the whole thing actually happened.

The tide book was consulted and Matty and seven year old Jamie were given a crash course in home popper manufacture 101. A little over two weeks later we were back at the same spot at 9pm. Within an hour, my suspicions were confirmed and we were rewarded with my best Brissie barra to date, a well conditioned 85cm specimen that was photographed, admired, then released to fight again. This second fish struck hard and jumped a few times, but it paled in comparison to the previous beast, which going on this fish we estimate must have been near, if not exceeding, the magic metre mark. A natural curiosity led me to investigate how many other anglers were encountering large Lates calcarifer in south east Queensland estuaries.

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Releasing a barra caught in central Queensland. Even though they may be unusual captures, barra around Brisbane are still subject to the usual size and bag limits as well as a closed season from 1 November to 1 February each year.

Historically, the most southerly distribution of natural populations of barramundi in Queensland was the upper reaches of the Noosa River, as evidenced by the pictures in my early 1980s version of Ern Grant’s Guide to Fishes of an 89cm, 8.6kg specimen. But these fish must have been few and far between. Having regularly live baited the Noosa River in the 1980s and ’90s, my colleagues and I never caught one. We can also vouch for the fact there were no small barra caught in cast nets and the like, suggesting there was little evidence barra actually spawned successfully in that system. Their historic existence in the Noosa River might instead be explained by southward recruitment of larval and juvenile barramundi spawned in rivers to the north that empty into Tin Can Bay and the Great Sandy Straits.

However, there has been a long term warming trend in our climate (see Sidebar 1 below), which may explain reports in recent years of people catching some metre-plus barra as well as occasional small barra in cast nets in the Noosa River. If reports of small barra are true, this could indicate that barra are now breeding successfully in that system. Furthermore, since artificial propagation of barramundi was developed in the 1980s, an increasing number of barra have been bred in south east Queensland to supply the aquaculture and ornamental fish industries. One thing about pet barra is they grow fast, and it’s known (rightly or wrongly) that people often discard them into local water bodies once they outgrow their tank.

The local grapevine and internet chat rooms indicated that occasional sizeable barra, probably released pets, were occasionally being caught as far south as the Logan, Coomera and Nerang Rivers. Other sources indicated that escapees from barra farms and fishing parks on the Sunshine Coast had led to reasonable populations of large barra up to 1.2 metres or more being found in some parts of the Maroochy and Mooloola Rivers, less than an hour’s drive from the Brisbane CBD.

Anecdotal records of recent barra captures from Caloundra, Pumicestone Passage and the lower reaches of the Caboolture and Brisbane Rivers were also represented on internet chat rooms. Indeed, it seems that barra are now being captured each summer in most of South East Queensland’s major waterways. As detailed on the Fishing World website, a 1.2 metre barra was also captured in a commercial net at Forster in central NSW, while a pet sized 48cm barra was also caught in the Georges River near Sydney.

Does this reflect global warming, increasing sportfishing pressure, or increasing numbers of barra being released? Or a combination of all three?

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In northern Australia mangrove jacks are often caught in the same locations frequented by barra. At the moment barra might be welcome bycatch for those targeting jacks around Brisbane. But who knows, in the future could jacks become welcome bycatch for Brissie barra anglers?

Certainly other tropical estuary species such as mangrove jacks are continuing to thrive in SE Queensland (see Sidebar 2 below), while a decent population of king threadfin salmon has become established in the Brisbane River. So why not barra?

My personal experiences of catching only barra bigger than 65cm around Brisbane, and not seeing evidence of fish less than 20cm, suggests that spawning, if it’s occurring at all, is not resulting in successful recruitment of juvenile barra in these areas at this time. South of Noosa, nursery areas in rivers with suitable wetland habitat in the brackish and freshwater reaches is scarce compared to the rivers further north, but remnant wetlands do still exist in some SE QLD rivers. However, since water temperatures in these estuaries can drop to 15°C or less in winter, this is still probably too low for year round survival of young of the year barra. So don’t hold your breath, we’ll need a few more years of warming before barra are likely to become self sustaining and a reliable target species for Brisbane anglers.

In the meantime, its important for Brissie anglers to realise that barra in estuaries and other tidal waters in Queensland are protected by a slot limit (minimum 55 cm, maximum 120 cm), as well as subject to a closed season from December 1 till 1 February each year. So if you’re lucky enough to accidentally encounter one during these times (and the summer months are when they’re most active), don’t make the same mistake as some SE Queensland anglers who’ve been caught keeping barra during the closed season. With the almost inevitable media interest in these captures, it’s not a good look when newspaper reports of your prize capture are used to incriminate you and the Fisheries Department comes knocking at your door.

Side Bar 1. Getting warmer

While there will always be some people who will deny anything of the sort, scientists across the globe have actual long term data showing that ocean temperatures are increasing. Oceanographic data from CSIRO shows that mean ocean temperatures around Australia have warmed overall by around 0.7°C, since 1910, with warming occurring at an even faster rate (around 0.1°C per decade) since 1950. Along the east coast the East Australian Current is the main driver bringing warmer water south, leading to relatively fast ocean warming in the South East of Australia in recent decades. This has been accompanied by southward range extensions for many marine species, including seaweeds, phytoplankton, zooplankton, and several species of fish. This trend, if it continues, will most likely result in the eventual establishment of barramundi populations in the estuaries between the Noosa River to the QLD/NSW border.

On the down side is the fact that warming seas are associated with rises in sea level. This latest rise actually started over 10,000 years ago at the end of the last ice age, when the sea level was around 120 meters lower than today. The rate of sea level rise averaged around 10-15 mm a year for over 8000 years, stabilizing at around the current level around 2000 years ago. Long term tidal gauge records show sea levels started rising again from the beginning of the 18th century, with a global average increase of 1.6 mm/year resulting in an overall sea level increase of over 20 cm between 1800 and now. Will coastal residents in a Venice-like SE Queensland be fishing for barra from their balconies in 100 years time ? Only time will tell.

Side bar 2. The case of King Threadfin – can barra follow them ?

Today, king threadfin salmon (Polydactylus macrochir) are a common capture for recreational anglers fishing in the tidal reaches of the Brisbane River. However, it seems this was not always the case. Early publications on the history of fishing in Brisbane and Moreton Bay by the likes of Thomas Welsby don’t mention the presence of king threadfin in the Brisbane River at the end of the 19th century. Yes, there were smaller striped threadfin or putty nosed perch (Polydactylus plebieus), which people like my late grandfather could account for first hand at least as far back as the 1930s (and I can remember capturing them myself as a kid in the 1970s).

Certainly, the populations of mulloway, cod, groper, bream, whiting, flathead, tailor and mangrove jack (as well as eastern cod in the upper freshwater reaches) were well described by net and line fishers during the 19th and early 20th centuries. But historically, the most southerly river with a good population of king threadfin was regarded as the Mary River, a few 100km to the north. In the mid 20th century, reference books like earlier Grant’s Guide to Fishes, occasional captures of king threadfin were reported from the Caboolture River (around 30km to the north), but it appears only in the 1970s and ’80s that rare captures of king threadfin from the Brisbane River were noted. However, by the 1990s it was evident that the Brisbane River harboured a good population of large king threadfin, and by the late 1990s these fish were being afforded scientific study.

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Threadfin salmon like this NT caught specimen are regularly caught in the Brisbane River. Image: Peter Zeroni

Study of the genetics and life history of king threadfin populations along Queensland’s east coast have since found that each major river system holds its own population of threadfin, with little evidence of connectivity or larval dispersal between different river systems. It is thought that colonisation of new river systems occurs through migration of adult fish in a “stepping stone” manner. The Brisbane River population is genetically quite different to the populations of threadfin further north. This begs the question – are king threadfin recent arrivals in the Brisbane River in the latter half of the 20th century, or have they been here the whole time?

I consider they are late arrivals due to the absence of records of their capture by early settlers. The most likely explanation for their establishment in the Brisbane River is due to a combination of a warming climate, and alteration of habitat by European settlers. Descriptions of the Brisbane River in the early 19th century by explorers such as John Oxley in 1823/24 depicted a shallower, clear running river so pristine that east coast cod were numerous in the upper reaches. Once Brisbane was settled by Europeans in 1824, over time the river was deepened along the middle and lower reaches by blasting and dredging to improve passage of ships, and the river became much muddier due to a much higher sediment load because of widespread clearing and development of the catchment. While these changes to habitat were devastating for eastern cod, threadfins which have evolved with small eyes and sensitive free sensory filaments at the base of each pectoral fin, are well adapted to life in muddy water.

While occasional adult king threadfin probably encountered the Brisbane River from time to time over recent millennia, perhaps it took a combination of a warming climate together with increased muddiness before the conditions were right for establishment of permanent breeding populations of these fine sportfish in the Brisbane River. These very same factors that worked in favour for king threadfin could also allow establishment of barramundi in the same places.

But, a combination of marginal winter water temperatures and scarcity of suitable freshwater wetland areas upstream (below the dams) would appear to reduce the likelihood of self sustaining barramundi populations being established anytime soon, as both are key factors limiting survival of young of the year fish.

So enjoy the occasional barra in SE QLD estuaries while you can, but don’t hold your breath for constant barra action anytime soon!

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