Sea cleaning crews paid for by tuna farmers collected around 500kg of marine waste and 45kg of fish oil every day this past summer.
Two vessels equipped with three crew members each were deployed throughout the summer season to react to reports of maritime litter received on two public hotlines by members of the public.
One vessel covered a northern route between Valletta and Mellieħa while another covered a southern one between Valletta to Żurrieq.
“The trash collected by the teams amounted to nearly half a ton of trash every day, apart from 45kgs of waste oil collected daily from the sea, and included all forms of maritime flotsam generated by various industrial practices or even recreational fisheries,” Aquaculture Resources Limited (ARL) said in a statement on Saturday.
“This trash included various plastics, jablo boxes, wooden pallets, organic waste and engine oils. Using special muslin nets, rather than a skimmer, the teams painstakingly collected the oil waste by concentrating it using booms before picking it up. In the case of complex spills, the ARL contacted Transport Malta to effect an immediate recovery of the oil waste.”
ARL is the operating arm of the Federation of Malta Aquaculture Producers, the lobby group representing fish farmers.
Fish farmers had announced the public hotlines and cleanup efforts back in 2018 as it scrambled to contain outrage at continued reports of sea slime reaching local shores.
But in its press release on Saturday, fish farmers sought to portray the clean-ups as part of a broader environmental mission.
“We seek to improve our clean-up endeavours each year: this is not a reactive mission, but a committed belief in playing our part in ensuring the health and cleanliness of our waters,” said ARL director Charlon Gouder.
Gouder noted that ARL had managed to clean up an oil spill report near Buġibba within hours with the help of clena-up NGO Żibel.
“These are the kind of synergies that we are looking for,” he said. “Ideally, many industries should be doing something similar, because waste can be generated by various maritime industries or seaborne tourism services.”
Sea slime is generated from mackerel or sardines that are fed to tuna caged in offshore pens. The concentration of this baitfish in cages makes it susceptible to strong currents – including ones generated by massive tuna, which can grow to larger than 240kg.
Environmental permits require tuna farms to have booms encircling their cages to collect any feed by-product or slime as it is generated. Operators must strike a balance between the size of the booms and ensuring adequate water flow into the cages, for the welfare of the tuna.
While tuna farms are widely acknowledged to be the primary culprit of sea slime reaching local beaches, the environmental regulator has also noted that some slimes are actually caused by algal blooms.
Such slime, referred to colloquially as ‘sea snot’, is caused when strong currents pick up algae dislodged from seaweed beds.