The Catch-22 is this - the Wilang (Gathang name for freshwater catfish) is believed to be under threat. To determine the conservation status and future of the species post-drought, population data in local rivers must be re-assessed.

For a river re-assessment to occur, a species must already have a reasonably high conservation status.

So as well as not being the prettiest fish in the pond and more than 25 years to formalise a species name for the Wilang, it is still not quite important enough to trigger an investigation to determine whether its conservation status is, in fact, important.

Aquatic ecologist Dr Keith Bishop, who has spent decades exploring and researching the life in our region's rivers, is making a splash about it.

He says it has been a frustrating 25 year wait for the Wilang to be formally identified as unique. And now, populations have been whacked by the impacts of drought.

Dr Bishop made first contact with the Wilang back in the 1990s when he returned to the NSW east coast after a decade working in the Northern Territory.

He was commissioned to assess the impacts of a proposal to extract water from the Bellinger River for the burgeoning population of Coffs Harbour.

"Environmentally and politically it was destined to fail - thankfully it soon did," Dr Bishop said.

"Nevertheless, for a year or so, I was out on that beautiful river trying to understand how large pumps would change river flows and impact the dependent aquatic life.

"They were not going to take all the water, but they could make pool levels fluctuate, diminish riffles between pools and encourage salt to come up from the ocean.

"It was a no-brainer that pumps making pool levels and riffles unnaturally fluctuate would be bad for the resident catfish which make nests in gentle-flowing gravel/cobble shallows during spring to early summer.

"So off I went working out exactly where the nests were and how vulnerable they would be.

"Something was odd though, instead of classic circular nests you usually see out west, the nests in Bellinger were very odd shaped - mostly they were sprawling and multi-lobed. Also, unlike the western catfish which build nests in still waters, the nests in the Bellinger were in moderate flowing water."

Catfish make nests by vigorously sweeping their tails over stony areas, removing fine sediments which clog up the between-stone spaces. The eggs are deposited in these spaces and free flowing water through them delivers vital oxygen to ensure rapid egg development.

Other species make similar nests in stony flowing areas, notably the salmon and trout from the northern hemisphere, and in their case, the nests are called redds.

Dr Bishop said about the same time, geneticists started to analyse the flesh of catfish and concluded there was an undescribed species - the 'Bellinger Catfish' - in four Mid North Coast catchments, the Bellinger, Macleay, Hastings and Manning rivers.

"More sophisticated analyses based on DNA molecular clocks indicated that this coastal catfish separated from the inland species between 1.6 to 2.6 million years ago. This would fall within a period - the Pliocene Epoch - of the last major geological uplift which formed the Great Dividing Range," Dr Bishop explained.

"Unfortunately, it is very difficult to formally describe a species based on genetic data, and if you could, it would be impossible to identify what you have in your hands by a river.

"To manage a species it needs to be described, accepted as a species, and you need know its limits of distribution and vulnerabilities. A taxonomist was needed after the geneticists found what they found, but one didn't show up for 25 years, and as a result, frustratingly, the management of the catfish was in a state of limbo for this time.

"This situation came about largely because taxonomists are becoming an 'endangered species' in Australia, and getting rarer."

Finally in mid-2017, tapping into a larger resource of taxonomists in the USA, a West Virginian with Australian co-authors published a species description in the journal of the American Society Ichthyologists and Herpetologists.

At last the catfish formally had a name and its distribution was identified - Tandanus bellingerensis and it was accepted that it only had a very restricted distribution in the Manning, Hastings, Macleay and Bellinger rivers.

The Wilang differs from the inland catfish in having higher counts of rays in its fins, higher gill-raker counts and strongly curved serrations on it pectoral spines.

In 2017 this new species was considered quite secure as previous surveys had shown it to be common. This was in contrast to the inland species, which in November 2008, was declared endangered due to drastic declines since the 1980s, likely caused by a broad range of factors.

Then came the 2019-20 extreme drought that delivered unprecedented dry conditions along the east coast.

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This drought appears to have had origins in 2014-15 as shown by low-flow records in the Manning River. From Dr Bishop's surveying in the Manning River system, the breeding of the Wilang came to halt around this time and they were appearing in widespread fish kills.

In 2019-20, the number of no-flow days in Mid North Coast rivers reached levels never recorded before. The upper Manning River recorded 289 days of no flow, the Barnard River 287 days, lower Manning River 63 days and the lower Hastings River 76 days.

Major fish kills on the back of bushfires were reported in the Macleay River in January 2020.

"Surveying in the Manning and Hastings River has shown a very worrying 90-100 per cent loss in their numbers in some catchments," Dr Bishop recorded in his own surveying.

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"As would be expected, the largest losses occurred in catchments which had the greatest number of days with no flows"

To reassess the security, or conservation status, of the Wilang there are many stringent hurdles to jump, Dr Bishop said.

Data on changes in their numbers post-drought is required in each of the river systems.

Dr Bishop has been recording changes in the Manning and Hastings rivers, but says there is no data for the Macleay or Bellinger rivers.

"I was hoping that NSW Fisheries with their very capable scientists could re-survey these rivers so to provide 'after' data. I am far from hopeful about this eventuating as I understand the department has only very limited resources for freshwater surveying and what they do have is mostly dedicated to the Murray-Darling system," he said.

"So here is the Catch-22 - to re-survey the rivers to reassess the Wilang's conservation status, resources are needed and these would only become available if the Wilang had a higher status - the frustrating circular trap is obvious.

"Alternatively, perhaps members of the public, citizen scientists, can report recent observations on the Wilang in the Macleay and Bellinger Rivers, particularly changes that have occurred since the 2019-20 drought."

Dr Bishop said photos of nesting sites would be valuable.

"Hopefully the Bellinger and Macleay rivers still hold robust populations of the Wilang subsequent to the 2019-20 drought," he said.

"If they don't, clearly the conservation status of Wilang should be put up to a higher level. This would hopefully allow resources to be made available, for example, to establish secure captive populations and perhaps develop breeding and re-stocking strategies.

"There is a glimmer of hope that the Wilang can 'right' themselves in the Manning system at least. Surveying I have just finished there has shown that the few Wilang that remain - all large adults - are investing in reproduction (making nests) at unprecedented levels.

"Perhaps they are somehow aware that if they don't successfully breed this season they are in very big trouble."

If you can assist Dr Bishop, visit his website.