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| Every year, Underwater Television surveys are carried out to monitor the seabed in several different locations |
For those who make a living on the water, the Nephrops norvegicus—better known as the Dublin Bay prawn, langoustine, or scampi—is a cornerstone of the UK fishing economy. However, managing these stocks requires more than just monitoring landings. It requires a specialized form of underwater detective work.
Recently, an international group of scientists gathered at the Agri-Food and Biosciences Institute (AFBI) in Belfast to refine the "art" of the Underwater Television (UWTV) survey. This annual training ensures that both veteran researchers and new analysts are calibrated to the same high standard before the summer survey season begins.
The Proxy Method: Counting Burrows, Not Prawns
The primary challenge in assessing Nephrops populations is their behavior. Unlike many commercial species that swim in the water column, prawns are seabed dwellers that spend the vast majority of their lives inside complex burrow systems.
Because the animals are often hidden, scientists cannot rely on counting individual prawns. Instead, they use the burrow as a proxy for the inhabitant.
The Technique: Researchers deploy cameras on sleds that are towed across the seabed in various locations.
The Identification: Analysts must distinguish a Nephrops burrow from those created by other marine life or natural depressions in the silt.
The Markers: A true prawn burrow typically features a "driveway"—a signature mound of excavated sand—and usually consists of two or more entrances to allow the animal to transit through.
A Collaborative Effort Across the Irish Sea
Monitoring the Irish Sea is a cross-border endeavor. Scientists from AFBI, the Marine Institute in Galway, and the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) in Lowestoft work in tandem to cover both the western and eastern sectors.
Dr. Pia Schuchert (AFBI) and Jennifer Doyle (Marine Institute) have spent years studying these habitats. Their work, alongside colleagues like shellfish scientist Chris Firmin, ensures that the data used to set fishing quotas is based on precise, non-invasive observation. This method allows for a comprehensive look at the habitat without the need to catch the animals during the assessment phase.
Economic and Environmental Stakes
The precision of these counts has significant real-world implications:
Economic Value: Prawn fishing is worth approximately £114 million annually to the UK and €61 million to Ireland.
Ecological Role: Beyond their market value, prawns act as a vital link in the marine food web, consuming algae and decaying matter while serving as a primary food source for larger predators.
Seabed Mapping: The data also feeds into broader projects, such as Northern Ireland’s initiative to become the first part of the UK to have its entire seabed recorded.
As the industry prepares for the upcoming season, the work conducted in Belfast ensures that the "peek-a-boo" nature of the Nephrops doesn't stand in the way of sustainable fishery management.
This story thanks to Louise Cullen, Louise is BBC News NI's agriculture and environment correspondent.
