Regular beach walkers will have seen the unusually high numbers of some fish species that were washed ashore before and around Easter.

If you were really unlucky you might also have seen one of the many dolphins washed up in the past month or so.

Young leatherjacket at Henley Beach, March 2013

Young leatherjacket at Henley Beach, March 2013

 

Friends member and marine champion Scoresby Shepherd discussed the massive kill with SARDI authority Marty Deveney in late March.

He noted that the species washed ashore are all poor swimmers, and that CSIRO has advised that sea temperatures along the coast have been up to 5 C warmer than the previous hottest temperatures recorded, with uniform temperatures throughout the water column.
Poor swimmers are unable to swim off to other waters or to surface waters. The role of the gale was merely to wash them ashore from over a wide area.

In other words this is an unprecedented marine heat wave similar to that on the WA west coast 3 years ago. The grimmer conclusion is that this is an extreme event that augurs the future for southern waters.

 

PIRSA issued the following statement last week:

FISH MORTALITIES UPDATE: No.1 – 5 April 2013.

 You would be aware of the recent reports of fish kills and dolphin deaths in SA waters. The reports of fish deaths have extended across both gulfs since the start of March. While the suspected cause of the fish deaths is increased warm temperatures due to the recent, prolonged hot weather in South Australia together with reduced oxygen levels in water caused by algal blooms, the cause of the dolphin deaths is still being investigated.

 On Wednesday, Minister Gail Gago released a statement announcing the appointment of a specialist cross agency team of senior officers from DEWNR, PIRSA, EPA and SA Water which will review all of the available information to see whether there is an adequate explanation. The team is led by myself. At this point in time, the available evidence is indicating that the likely explanation for the fish kill is an algal bloom linked to warm gulf waters and nutrient upwelling. This is supported by the preliminary investigations and analysis of water quality and fish mortality.

 The EPA has ruled out any link with the desalination plant – the water quality parameters are well within prescribed limits. The fish kills under investigation extend across both gulfs (as far as Dutton Bay, north of Coffin Bay, and Port Neill also on Eyre Peninsula) and the South East.

 To ensure that interested stakeholders are kept fully informed on this issue, we have established an email network where we will keep people informed of the progress of our investigations. We have also established a website at www.pir.sa.gov.au/fishmortalities where we will be posting updates and information, including FAQs, media releases and backgrounding about this matter. Progress reports will be published as we proceed.

 Any fish or other marine life mortalities can be reported by phoning FISHWATCH on 1800 065 522.

 Please feel free to send this email on to interested colleagues.

 Scott Ashby,

Chief Executive, Primary Industries and Regions SA

 

MODIS satellite image of the gulfs in early March

MODIS satellite image

This image taken on March 6th shows much higher chlorophyll levels on the western sides of both Gulfs – indicated by the red colour. Deeper waters, with 10x less chlorophyll are blue or green coloured.

What about the Dolphins?

(text below based on news item from Adelaide Now 4/4/2013 and an ABC 891 radio interview on 3/4/2013)

 

Senior researcher and curator of mammals at the South Australian Museum, Dr Catherine Kemper said early results from the first dolphin autopsy had provided no clear answers, but revealed one possible cause.

Around 17 reports of dolphin carcases washing up on South Australian coasts have been reported in the past month.

It is the largest spike of reported deaths of marine mammals locally for a long time.

Dr Kemper said the last large spike in dolphin deaths was the result of shootings, with five reported deaths in the late 90s.

She said whilst it was not possible to draw conclusions from a single autopsy, traces of E. coli found around the animal’s blow hole and abnormal organ sizes were of concern.

With the amount of sealife washing up on local beaches recently, Dr Kemper said it may be possible, as has happened in other areas around the world, that biological toxins may be responsible for the deaths.

“This happens when you have red tides, algal blooms and dinoflagellates.  The bacteria are digested by smaller fish and work their way through the food chain. We wouldn’t normally do testing for this, but we will this time.”

 

Whale and Dolphin Conservation Society science and education manager Dr Mike Bossley urged the State Government to set up a cross-departmental taskforce to investigate.

He said there was not enough co-operation between those investigating dolphin deaths, algal blooms and washed-up fish.

Dr Bossley said the cost to perform tests – particularly for dolphins – also was a problem.

“I’m concerned for two reasons – one is that the (deaths) are quite high and secondly, that we still don’t have any real idea of what’s causing it,” he said.

 

 

One Response to Fish and dolphin deaths

  • Jim Douglas says:

    These deaths are extremely alarming .It would be hard to discount raised water temperatures as researched by the CSIRO mapping . I hope the tests can find the source and that there are no cover ups because we all need to know what has been the causation.

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