2 Monitoring of Marine Aquaculture
71
2.3 Monitoring the Environmental Impacts
of Aquaculture in Malta
2.3.1 Introduction: Development of Aquaculture
Activities in Malta
Aquaculture on an industrial scale started in Malta around 1991, following initial
land- and sea-based experimental and pilot projects undertaken in the mid-1970s
and early 1980s. During the period 1991 to 2000, the activity mainly involved culture of sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) in offshore
cages located a few hundred metres or less from the shore. Production of these two
species increased steadily from around 100 tons in 1991 to 2000 tons in 1998
(Axiak et al. 1999). The offshore sea bass and sea bream farms, owned by some six
different operators (Schembri et al. 2002), were sited in eight localities, all of which
were relatively sheltered and supported extensive seagrass (Posidonia oceanica)
meadows. Water depth at the different fish farm sites ranged between 10 m and
22 m. On the other hand, land-based coastal aquaculture activities contributed only
2% (equivalent to an annual production of 50 tons of sea bream) to the total local
aquaculture production. However, the land based operations also included two
hatcheries for sea bream, one of which was located within the National Aquaculture
Centre and which at peak production was contributing up to 2.5 million sea bream
fry per year, most of which were exported to Europe (Axiak et al. 1999). In the late
1990s, strong competition from fish farms based on mainland Europe, and the high
operational costs incurred by local farms, particularly freight and levy charges
imposed on the exported product, led to a general decline in culture of sea bass and
sea bream, and the attention of some local fish farmers turned to the relatively new
and lucrative activity of tuna-farming (Schembri et al. 2002).
Tuna farming, also commonly referred to as “tuna penning”, is a relatively recent
but highly successful enterprise that was introduced to Europe in 1979 and adopted
on a large commercial scale in the 1990s. Tuna farming is classified as capture-based
aquaculture and differs from traditional aquaculture in that the farmed stock is
derived from catches taken from wild populations, while the captive tuna are fed
fresh fish (e.g., herring and mackerel) (Ottolenghi et al. 2004). In Europe, tuna penning has been (to date) restricted to the Mediterranean, where the main species
farmed is Thunnus thynnus, the Atlantic Bluefin Tuna. The intensity of tuna farming
has increased steadily in the Mediterranean over the last decade or so, reaching a
current total annual production of around 16,000 tons. However, information on the
influence of tuna farming on the marine environment, both outside and within
European coastal waters, is somewhat lacking and there is a dearth of published data
on the environmental impacts of the activity, while data on potential adverse effects
resulting from indirect activities, for example, the impacts of the baitfish fishery that
supplies the fresh feed for tuna, is unavailable. Moreover, in view of the large and
increased catch effort of tuna fishers to meet the farms’ demand, information on the
71
2.3 Monitoring the Environmental Impacts
of Aquaculture in Malta
2.3.1 Introduction: Development of Aquaculture
Activities in Malta
Aquaculture on an industrial scale started in Malta around 1991, following initial
land- and sea-based experimental and pilot projects undertaken in the mid-1970s
and early 1980s. During the period 1991 to 2000, the activity mainly involved culture of sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) in offshore
cages located a few hundred metres or less from the shore. Production of these two
species increased steadily from around 100 tons in 1991 to 2000 tons in 1998
(Axiak et al. 1999). The offshore sea bass and sea bream farms, owned by some six
different operators (Schembri et al. 2002), were sited in eight localities, all of which
were relatively sheltered and supported extensive seagrass (Posidonia oceanica)
meadows. Water depth at the different fish farm sites ranged between 10 m and
22 m. On the other hand, land-based coastal aquaculture activities contributed only
2% (equivalent to an annual production of 50 tons of sea bream) to the total local
aquaculture production. However, the land based operations also included two
hatcheries for sea bream, one of which was located within the National Aquaculture
Centre and which at peak production was contributing up to 2.5 million sea bream
fry per year, most of which were exported to Europe (Axiak et al. 1999). In the late
1990s, strong competition from fish farms based on mainland Europe, and the high
operational costs incurred by local farms, particularly freight and levy charges
imposed on the exported product, led to a general decline in culture of sea bass and
sea bream, and the attention of some local fish farmers turned to the relatively new
and lucrative activity of tuna-farming (Schembri et al. 2002).
Tuna farming, also commonly referred to as “tuna penning”, is a relatively recent
but highly successful enterprise that was introduced to Europe in 1979 and adopted
on a large commercial scale in the 1990s. Tuna farming is classified as capture-based
aquaculture and differs from traditional aquaculture in that the farmed stock is
derived from catches taken from wild populations, while the captive tuna are fed
fresh fish (e.g., herring and mackerel) (Ottolenghi et al. 2004). In Europe, tuna penning has been (to date) restricted to the Mediterranean, where the main species
farmed is Thunnus thynnus, the Atlantic Bluefin Tuna. The intensity of tuna farming
has increased steadily in the Mediterranean over the last decade or so, reaching a
current total annual production of around 16,000 tons. However, information on the
influence of tuna farming on the marine environment, both outside and within
European coastal waters, is somewhat lacking and there is a dearth of published data
on the environmental impacts of the activity, while data on potential adverse effects
resulting from indirect activities, for example, the impacts of the baitfish fishery that
supplies the fresh feed for tuna, is unavailable. Moreover, in view of the large and
increased catch effort of tuna fishers to meet the farms’ demand, information on the