The Estuary Stingray inhabit Lake Cathie and this particular species of stingray are vulnerable under the International Union for Conservation of Nature Red List and are considered to be threatened with extinction.
If the lake is not opened in the immediate future they will die, which is extremely distressing to watch, as they will suffer a slow and painful death.
The stingrays along with the fish that are still remaining in the lake have Epizootic Ulcerative Syndrome (EUS) or 'Red Spot Disease' usually caused by poor water quality.
Red Spot Disease is caused by a fungus (Aphanomyces invadans) and shows as red lesions (sores) or deep ulcers.
The fungal infection also makes marine life prone to secondary bacterial infections.
It should also be noted that fish should not be consumed if they have Red Spot Disease because it can be harmful to human health.
Unfortunately it could be months before the lake is opened because the council has to provide an REF report (Review of Environmental Factors) to the state government.
The last one was updated in 1995 and is not current.
An REF is an environmental assessment under Part 5 of the Environmental Planning and Assessment Act 1979 (EP&A Act) that is required as part of the assessment of activities needing approval under NSW legislation.
It assists the determining authority's determination of whether the activity (in this case opening of the lake) is likely to have a significant effect on the environment or significantly affect threatened species, populations or ecological communities or their habitats, in which case an environmental impact statement (EIS) and/or species impact statement (SIS) will need to be prepared and considered before approval may be granted (s.112 EP&A Act).
Council have stated that it could be months before the REF report is provided.
If it is going to take so long something needs to be done in the interim to preserve what life we have left in the lake especially our threatened stingrays.
It seems barbaric that something that aims at protecting a threatened species will take so long to produce and to be approved in this current situation with the lake.
The waiting for this REF will be the demise of our precious stingrays.
In November I asked the Council if the sand could be graded at the lake/ocean interface to allow some clean oceanic water into the lake at high tide - this would certainly help to preserve the marine life that is left in the lake.
Unfortunately council have not acted upon this. It is inhumane to allow the stingrays to suffer like this, the water quality is so bad it is causing them to die. We have already lost many stingrays as well as hundreds of other fish (multiple species).
Fish kills and stingray deaths were reported to DPI (Department of Primary Industries) on multiple occasions since January 2018 and Stingray deaths were reported in October, November and December last year.
There have been more fish deaths this week.
Still nothing has been done to help preserve what life is left. Even if some clean ocean water is pumped into the lake that would help.
The only other way to save the stingrays and fish would be to relocate them to another estuarine / coastal lagoon ecosystem, however a permit would be required for this.
Relocating the Stingrays would be a mammoth task as they would have to be acclimatised to their new environment to prevent shock due to changes in water chemistry.
At the moment the stingrays are being subjected to salinities much higher than normal seawater due to the evaporation from the lake and drought conditions.
The oxygen levels are low and this will get worse as temperatures rise throughout the summer months, this is because less oxygen dissolves in water as temperature increases.
To exacerbate this, high salt levels also cause a decrease in oxygen concentration.
Lack of oxygen and high salinities have been some of the contributing factors to fish deaths in the lake.
Unfortunately the stingrays cannot be relocated to the open ocean as this is not their natural habitat.
The stingrays are also starving as there is a lack of food in the lake for them.
They are benthic / bottom feeders and feed on benthic invertebrates such as crustaceans (shrimp and crabs) and molluscs such as Pipi's, and other bivalves that live on and in the sediments.
They will also feed on oysters. Usually the stingrays move over mudflats to feed with the incoming tide.
Most of this food source has died off due to poor water quality. The stingrays are emaciated and are hungry.
As stated previously the stingrays are vulnerable under the IUCN Red List and are considered to be threatened with extinction.
Once common in New South Wales however, populations have declined in both abundance and distribution due to habitat loss during coastal development.
Adults reach a disc width of 120 cm and young are born at 11 cm disc width.
Both adults and juveniles are present in the lake and they need clean ocean water as this will help them to fight off their Red Spot infections and provide them will food.
It is necessary that this happens immediately to give them any chance of survival.
Dr Deb Geronimi has a PhD in Estuarine Biology.