CSIRO researchers document 2.8 million eels aggregating at Tasmanian seamount

A rare and unexplained phenomenon

In a study led by CSIRO researcher Ben Scoulding, scientists quantified an aggregation of approximately 2.8 million basketwork eels at Patience Seamount, a site in Tasmania’s Huon Marine Park. The aggregation spans roughly 3 kilometers long and 2 kilometers wide, extending several hundred meters into the water column.

The phenomenon was first observed in 2007 during the establishment of the Huon Marine Park. Follow-up surveys in 2015 and 2018 confirmed the eels’ consistent presence, though their exact reasons for gathering remain unclear. Scientists hypothesize that mating is the most likely explanation, but no definitive evidence has been found.

Seamount characteristics and species distribution

Patience Seamount rises to a peak depth of 857 meters from a base of 1,250 meters. It is the only site among the 120 seamounts in the Huon Marine Park where such a large aggregation of basketwork eels has been observed. Fishers dubbed the site ‘Eel Hill’ in the 1980s due to its association with the species.

The seamount’s topography appears to influence species distribution. Basketwork eels prefer flatter terrain at depths greater than 1,050 meters, while orange roughy, another deep-sea species, occupy shallower areas near the peak and steep slopes at around 1,000 meters.

Unanswered questions and future research

While the aggregation’s numbers peak between March and May, scientists do not know when the eels arrive or disperse. The reproductive condition of sampled eels suggests spawning activity, but low catch rates during research could indicate either gear limitations or reduced feeding during this period.

Researchers aim to gather more direct evidence to confirm whether the eels are gathering for reproduction. They also seek to understand the eels’ post-spawning movements and larval drift patterns, which could provide insights into their life cycle and conservation needs.

What this means

Lazyfounder analysis — our interpretation, not reported fact.

The discovery of such a massive eel aggregation underscores how little is known about deep-sea ecosystems, even in protected areas. For marine researchers and conservationists, this phenomenon presents an opportunity to study species behavior in extreme environments, which could inform policies for protecting underwater habitats. Startups working in marine technology or deep-sea exploration may find value in developing tools to monitor or analyze such aggregations, particularly as demand for oceanographic data grows. The fact that this aggregation is unique to Patience Seamount also raises questions about what makes the site special—answers that could redefine our understanding of seamount ecology.

Key takeaways

• This discovery highlights the need for further deep-sea research to understand species behavior, which could inform marine conservation strategies and policies.
• The unique aggregation at Patience Seamount may offer insights into how underwater ecosystems function, particularly in seamount environments.
• For startups and researchers in marine technology or conservation, this phenomenon presents opportunities to develop specialized tools for deep-sea observation and data collection.

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