Fisheries authorities and local fishermen are at loggerheads over what killed thousands of estuarine fish in Tallow Creek, Byron Bay last week.
Just after Christmas, locals noticed the fish kill at the mouth of the creek and further upstream involving estuarine species such as flathead, mullet, whiting as well as eels and crustaceans.
A lack of oxygen in the water has been blamed for the kill, but just how the sudden de-oxygenation of the water in the creek (known as an intermittently closing and opening coastal lagoon) happened is in dispute.
A spokesman for the Department of Primary Industries (DPI) told Echonetdaily that an inspection by Cape Byron Marine Park rangers confirmed a ‘minor fish kill’ in the creek with between 1,000 and 2,000 fish killed.
The spokesman said ‘schools of healthy whiting and mullet were observed in the lower reaches of the creek’ during that inspection.
‘The fish kill coincided with a drop in water level in the creek over a short period of time, indicating that the kill was caused by the opening of the waterway.’
‘DPI is unable to confirm whether it was a natural opening with high tide and high water levels, or whether it was an assisted opening. There were large high tides around the time of the fish kill.’
But Byron Bay Deep Sea Fishing Club secretary Dan Bode told Echonetdaily that the level of deoxygenated water in the creek had become way too high due to the creek opening being ‘blocked’.
Mr Bode said natural processes had allowed the mouth of the creek to be ‘fused’, blocking it up and allowing backed up water to deoxygenate, causing the fish kill.
He said the mouth should be forcibly opened or ‘scraped’ by authorities to prevent the ‘fusion’ and subsequent fish kill.
‘With the blockage, levels of this water get higher, suffocating creek bank vegetation such as marshes and grasses as well as the fish,’ he said.
‘The marine park was made aware of the fish kill on December 29 yet by the 30th absolutely nothing had been done to warn swimmers with signs and people still swimming there with dead fish lying only 60 metres upstream,’ Mr Bode said.
But Byron Shire Council’s acting general manager Phil Warner told Echonetdaily that staff inspected the site to assess potential health impacts on swimmers, concluding it was ‘not an issue’ and that no further action was required.
Mr Warner said the dead fish would be left to decompose naturally or for scavengers to clean up.
Mr Bode also took aim at authorities over the rehabilitation of the estuary.
‘This fish kill coincides with 24mm of rainfall during a 48 hour event period and some big rains on December 22. We believe the Byron Bay community may have been exposed to a preventable fish kill within Cape Byron Marine Park,’ he said.
‘Non-indigenous fishermen have been locked out of the catchment on the pretext that Cape Byron Marine Park would effectively manage and rehabilitate that system, and now we’re experiencing a fish kill.’
Mr Bode said scraping of the sandbar level at the creek mouth would ‘act as a planned habitat management fuse, breached only at times of natural flooding’.
‘The fundamental problem with the Tallow Creek sandbar fuse is that the 1.8-2.2m AHD heights are far too high to prevent fish kills at Tallow Creek.
‘At the neighboring Belongil Creek system which is larger and in a much poorer pre-marine park state, council have been conducting regular sand scraping at a 1.1m AHD with excellent success and zero recorded fish kills in over 10 years.
‘Prior to the forced openings at Belongil Creek, substantial fish kills occurred every couple of years in that system. It must also be noted that this Belongil Creek system filters a polluted industrial area and also Cumbumbin Swamp.
‘In the period from 2009 to the present, it is uncertain whether any approvals for scraping works at Tallow Creek were applied for by Council, or granted to Council by Cape Byron Marine Park. It is also uncertain whether Cape Byron Marine Park refused Byron Shire Council applications for sand scraping works at Tallow Creek. Because of the Xmas break, there is no information about the way Council monitoring has been conducted since the Tallow Creek Floodplain Risk Management Study and Plan was adopted by Council and the Cape Byron Marine Park.
‘The Cape Byron Marine Park are the legislated managers and caretakers of our local Marine Estate and they locked anglers out under the pretense that they would rehabilitate these estuarine systems. You will no doubt agree that any fish kill in a NSW Marine Park in 2012 is socially and environmentally unacceptable at a time when controlled openings have been proven to both protect and enhance habitats within the Cape Byron Marine Park.
But the DPI spokesman said Tallow Creek has a history of similar events, as published in the 2009 Tallow Creek Floodplain and Risk Management Study and Plan
The spokesman said the report noted that ‘the biodiversity study also identifies current environmental concerns for the area. The aquatic environment has been impacted by the previous unregulated opening of the creek to the sea. This unregulated opening occurred after prolonged periods of high water levels in Tallow Lake and resulted in immediate release of water from Tallow Lake. The biodiversity study notes that the sudden unregulated release resulted in unfavourable mixing of deoxygenated water from the lake and oxygenated marine water causing fish and bird kills’.
Late last year, the department warned residents of coastal communities that excavating the entrances of lakes, lagoons and intermittently opening creeks could have long lasting and severe consequences for fish and fish habitat.
The warning came after a channel was dug out at the mouth of Bonville Creek near Coffs Harbour in an attempt to open up the creek.
DPI director of fisheries compliance, Glenn Tritton, said a number of Sawtell residents used shovels to dredge a channel from the mouth of Bonville Creek to the ocean, which had been closed beforehand.
‘Many people wrongly believe that opening creeks and lagoons can improve water quality or enhance fish recruitment, however, this is not the case,’ Mr Tritton said.
‘Similar openings of lakes, lagoons and creeks in the past have resulted in severe environmental damage.
‘Opening closed creeks and lagoons to the ocean in the wrong way can lead to low dissolved oxygen levels, increased exposure, death of aquatic vegetation and large fish kills.’