Studies still ongoing for relocation of tuna pens

‘There currently is no specific site for the North Aquaculture Zone’

james
James Debono
7 April 2017, 8:31am
The cages have to be deployed in water deeper than 50 m but not deeper than 100 m as divers are not supposed to work in such depths
The cages have to be deployed in water deeper than 50 m but not deeper than 100 m as divers are not supposed to work in such depths
The Planning Authority had given the owners of tuna pens in the north of Malta till May to relocate further offshore, but studies have still to determine an adequate zone where these can be relocated without causing ecological harm to the seabed.

One major constraint on the search for a an aquaculture zone in the north of Malta is that this must be located at a distance of at least 300 m from the current bunkering zone at Is-Sikka l-Bajda. The cages have to be deployed in water deeper than 50 m but not deeper than 100 m as divers are not supposed to work in such depths.

The Aqua culture zone will be located at a minimum distance of 4.5 km from the shore. 

Preliminary studies on a large area north of Qawra point in Saint Paul’s Bay have indicated that the area is rich in ecological habitats, which may be harmed by nutrients released in to the sea from fish farms.

A bathymetric survey carried out by ADI – an Environment Impact Assessment consultancy firm- confirmed that the area is largely rich in maerl and rhodoliths; coralline red algae which grow at a rate of 1mm a year.  

A Project Development Statement (PDS) presented to the Environment and Resources Authority by the Department of Fisheries concludes that further environmental studies are required to assess the impact of tuna pens on these habitats. 

The Environment Resources Authority is currently determining terms of reference for this study.

Malta already has a designated Aquaculture Zone in the south east of Malta which had been approved despite opposition by the Marsaskala local council in 2005.

According to the Project Development Statement the development of an additional Aquaculture Zone in the north of Malta is required “to satisfy the Government’s policy for aquaculture development and growth” and is required to enable the operators “to satisfy the PA’s orders and relocate to a permitted Aqua culture zone further offshore”. 

Where will the tuna pens go?

In September 2016, the Planning Authority revoked ten permits for the four existing operators following extensive complaints of oily scum in coastal waters and due to various illegalities related to the siting and number of cages. However, the PA allowed the operators to relocate their operations to alternative suitable aquaculture zones located further offshore. 

The Authority also imposed a timeframe for the relocation, which has to start before the 2017 summer season. Cages, moorings, chains and other tackle are to be removed from the current farming locations by the end of May 2017. 

Two of the operators that operated off Marsaskala and Marsaxlokk, respectively, have since obtained concessions to operate within the aqua culture zone, which had already been approved in the south of Malta.  But this site does not have enough space for the fish farms already located in the north of Malta. 

Yet despite the rigid timeframes, it is highly improbably that an alternative site will be found for these fish farms.

“There currently is no specific site for the North Aquaculture Zone. What we have is a search area, which was studied through remote sensing. The EIA might have to look at other sites outside of this location and hence the final location for the NAZ will be determined through the EIA process”, ADI consultants conclude in the Project Development Statement presented to the PA.

The Bathymetric survey was originally been commissioned by AJD Tuna Ltd as part of their application to relocate their farms from St Paul’s Bay and Comino. Subsequently ERA informed AJD Tuna Ltd that they could not entertain an application for relocation unless this is to an established Aquaculture Zone. Since all such zones are owned by the Department of Fisheries, an application to create such a zone was subsequently presented by the department.

How to avoid the oily slick

The oily slick consists of a combination of fish oils, melting ice, body fluids, and fish mucus
The oily slick consists of a combination of fish oils, melting ice, body fluids, and fish mucus
The most visible and notorious environmental impact from tuna farms is the oily slick that is visible at the surface of the sea for several miles depending on sea currents and wind direction. The presence of sulphur is responsible for the bad smells.

The oily slick consists of a combination of fish oils, melting ice, body fluids, and fish mucus released from the baitfish as it thaws in the feeding cage. It takes four days for the slick to decompose.

Since feeding takes place twice daily, this slick is released once in the morning and once in the afternoon from each tuna cage. 

Some operators use a skimmer to collect as much of this oily slick as possible before it leaves the site but this system is not completely effective.

The PDS concludes “relocating existing tuna farms to a location further offshore will help to reduce the impact of this discharge on inshore locations and uses”.

Still under unfavourable sea current conditions, the slick can still reach the shore if not collected. The use of skimmers, even if not 100% effective is recommended.

But while oily slick is the most visible environmental threat, tuna pens also have a more long-term environmental impact.

Uneaten feed passes through the net and settles on the seabed, which, can result in an accumulation of organic carbon and nitrogen in the sediment beneath the cages or in the direction of the prevailing currents. Fish faeces release ammonia, nitrate, and phosphate in soluble form. These nutrients contribute to the overgrowth of marine plants and algae.

Blood discharged in to the sea as a result of the slaughter of tunas may also attract predators like sharks. But to date there has been no evidence that this activity attracts sharks or other predators. “Indeed, no such occurrences have been reported in the 16 years since the first tuna farm was set up locally,” the PDS states. 

Tuna farming operations also have a toll on the wider fish populations. While tuna populations are regulated very closely by ICCAT, which adjusts fishing quotas regularly to maintain the population levels no such regulations exist on the capture of the baitfish species, and the impact of this fishery can be substantial on the fish stocks in question. 

james
James Debono is MaltaToday's chief reporter on environment, planning and land use issues, ...