DistantNews
Support us
🇦🇺 Australia /Environment & Climate

Blood-sucking, eel-like fish may be another casualty of algal bloom

From ABC Australia · () English

Translated from English and summarized by DistantNews. Read the original for the full story.

At a glance

In-depth Named sources Ongoing story
  • Researchers found no lampreys during two recent monitoring periods, despite usually catching between 20 and 100 during their winter migration into the Murray River.
  • Scientists say South Australia's harmful algal bloom may have affected the fish, but climate-driven changes or undetected deaths could also explain their absence.
  • The bloom has covered more than 20,000 square kilometres since March 2025 and killed about 1 million marine animals across more than 600 species, according to the Australian Marine Conservation Society.

The disappearance of a blood-sucking, eel-like fish might sound like welcome news to some people, but scientists in South Australia fear lampreys may be another casualty of the region's devastating algal bloom.

This year, unfortunately, we haven't caught any despite trying reasonably hard.

· Chris BiceThe SARDI senior researcher described the results of the latest lamprey monitoring.

Each winter, the South Australian Research and Development Institute uses traps at fishways to monitor lampreys moving from the ocean through barrages and into the Murray River. Researchers usually catch between 20 and 100 fish. During the past two monitoring periods, they caught none.

Senior researcher Chris Bice said the team had tried “reasonably hard” but had not found a single lamprey. He acknowledged that the “incredibly cryptic” fish can be difficult to catch, yet said the weight of evidence made it fair to suspect the algal bloom had affected their upstream migration.

On the weight of evidence, I think it's pretty fair to say that the algal bloom may have had an impact on the upstream migration of these fish.

· Chris BiceBice assessed the possible connection between the missing lampreys and the algal bloom.

The harmful bloom began in March 2025 and spread across more than 20,000 square kilometres along South Australia's coast. The Australian Marine Conservation Society says it killed approximately 1 million marine animals from more than 600 species. Floodwater, coastal upwelling and a marine heatwave contributed to the event.

Most farmers will tell you there's been some really weird things around climate and that may have also changed how the lampreys migrate.

· Faith ColemanThe estuarine ecologist offered climate-related changes as another possible explanation.

Lampreys belong to an ancient group of jawless vertebrates and resemble eels, though they are unrelated. Estuarine ecologist Faith Coleman said the bloom might be one factor among several. Unusual climate conditions could have changed migration patterns, while dead lampreys might have gone unnoticed if they sank instead of floating to shore. SARDI has monitored lamprey movements for about a decade, focusing on their migration into freshwater.

There is a question of whether they float when they die or whether they sink.

· Faith ColemanColeman explained why lamprey deaths might not have been detected along the shore.
About this summary

Originally published by ABC Australia in English. Translated, summarized, and contextualized automatically by DistantNews, with a note on how the source frames the story. Not individually reviewed before publishing. How this works.

More Stories

From Our Blog