Concerns raised over fish slime effects on health, but no studies yet carried out

Public consultation on proposed expansion of tuna cages carried out, with a Stop the Slime campaign representative disputing fish slime has no environmental effect

No studies have been carried out regarding possible adverse health and environmental impacts of fish slime created by the food fed to caged tuna
No studies have been carried out regarding possible adverse health and environmental impacts of fish slime created by the food fed to caged tuna

Concerns about the effects of fish farm slime on health and the environment have been raised during the public consultation process on the application for an expansion in the number of tuna pens.

Stop the Slime campaign representative Nicolai Abela said that research carried out by government entities in 2016 showed that the slime - which, in cases where it has reached the shoreline, has been the subject of numerous compaints by the public due to its foul smell - is considered an imminent threat to the environment, including to marine life along the coastline, and also has an effect on human health.

Abela aired his views at a public consultation held today, organised by the Environmental Resources Authority, meant to collect feedback on the Environmental Impact Assessment process for the tuna cage expansion.

In January this year, Azzopardi Fisheries had filed an application to double the number of tuna cages, in the Sikka l-Bajda area, from 12 to 24, bringing the total biomass within them to 3,300 tonnes of fish. The total biomass would be kept by Azzopardi Fisheries and Malta Mariculture Limited (MML).

The area in question, five kilometres off the coastline, is ecologically protected, with an EIA carried out earlier this summer having suggested that proper management may reduce the negative impact of a tuna cage extension.

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Regarding the health risks, Abela said that he’d had “reports from several dermatologists who confirmed that if contact is made with the slime, it should be removed as soon as possible with soap, as it can cause skin irritation and even boils”.

“From my experience, it’s very hard to remove. This health risk seemed to not have been included in the EIA – people are coming in contact with the fish slime,” he said.

Responding to Abela’s concerns, marine ecologist Adrian Mallia, representing the consultancy firm which carried out the EIA, said however that no formal studies had been carried out about any possible environmental or health effects of fish slime.

“It hasn’t yet been studied what the environmental impact of the oils is, but being a natural product, it is unlikely it would have such an effect,” Mallia said, “The focus now should be on ensuring good practices on these farms, in order to contain the impact within them.”

Arguments were also raised regarding why the tuna cages were located in a protected area, with the ERA responding that the fact that a tract of sea is protected, did not mean no development could take place there, as long as an assessment determines that the impacts would not be significant.

Others asked why the tuna pens were located only 5km offshore, and not further out, with Mallia asserting that currently technological limitations might not make it possible to move too far out to sea.

"It's a greater challenge operating further out, and different technology would be needed, as the sea gets progressively deeper," he said, "In reality even if you move further away from Malta, you might end up closer to Gozo instead," he pointed out.

Mallia emphaised that the application proposal is not to increase the fish biomass in the pens, but to lower the stocking density by having more cages. "The biomass will not exceed a maximum of 3,300 tonnes, which is the limit allowed now" he said.

Regarding the bait fish feed given to the tuna – the source behind the smelly slime – Mallia said over 94% of the 5.5 tonnes of fish given to each cage, every day, was ingested by the tuna, with 5% being lost as fish oil.

Around seven cubic metres of fish oil would be released each day per cage into the open sea, according to a model for the 24 cages, Mallia said.

The trajectory of this – whether it reaches the coast or not – would vary widely according to the prevailing winds. However, he said, the scenarios in the models were very complex, their outputs were not absolute, and they were mostly useful for comparisons.

Written submissions regarding the application can be made by 18 September.

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