State of the Bay Report 2011-Final.pdf - Anchor Environmental

Mussels
Oysters
Abalone
Scallops
Red Bait
Seaweed
State of Saldanha Bay & Langebaan Lagoon 2011
Activities & discharges
3.3.10 Mariculture
Saldanha Bay is the only natural sheltered embayment in South Africa and as a result it is regarded
as the major area for mariculture (Stenton-Dozey et al. 2001). The Bay was zoned to cater for
mariculture operations in 1997 and approximately 1 000 ha were demarcated for mariculture
(Stenton-Dozey et al. 2001). A total area of approximately 145 ha has been allocated to seven
mariculture operators within Saldanha Bay (Table 3.9). All operators farm mussels and six of the
operators also farm oysters. Abalone, scallops, red bait and seaweed are each cultured on one of
the farms. Blue Bay Aquafarm, the largest and oldest of the current farms, have had rights to
approximately 50 hectares of water at the entrance of Small Bay since 2002. The other six operators
have had rights to smaller areas in both Small Bay and Big Bay since 2010. All rights have a
maximum duration of 14 years.
Table 3.9. Details of marine aquaculture rights issued in Saldanha Bay (source: DAFF pers. comm. 2011)
Products
Company
Area (Location*)
Duration of
right
Blue Bay Aquafarm (Pty) Ltd x x 50.9 ha (SB) 2002-2016
Blue Sapphire Pearls CC x x x x 5 ha (SB) 2010-2024
Imbaza Mussels (Pty) Ltd
(previously trading as Masiza
Mussel Farm (Pty) Ltd)
x 30 ha (SB) 2010-2024
Striker Fishing CC x x x 25 (BB) 2010-2024
West Coast Aquaculture (Pty)
Ltd
x x x 15 ha (SB) 2010-2024
West Coast Oyster Growers CC x x 5 ha (SB) 5 ha (BB) 2010-2024
West Coast Seaweeds (Pty) Ltd x x 5 ha (SB) 5 ha (BB) 2010-2024
Raft culture of mussels has taken place in Saldanha Bay since 1985 (Stenton-Dozey et al.
2001). Larvae of the mussels Mytilus galloprovincialis and Choromytilus meridionalis attach
themselves to ropes hanging from rafts and are harvested when mature. Mussels are graded,
washed and harvested on board a boat. Overall mussel productivity peaked at approximately 740
tons in 2008 following a lull in productivity between 2005 and 2007 (Figure 3.35). There was a
decrease in productivity in 2009 which was followed by an increase in 2010 (with the peak
productivity at 700 tons). In 2009 and 2010 the mussel sub-sector (based in Saldanha Bay) was the
second highest contributor to the overall mariculture productivity for the country (DAFF 2010, DAFF
2011).
A study conducted between 1997 and 1998 found that the culture of mussels in Saldanha
Bay created organic enrichment and anoxia in sediments under mussel rafts (Stenton-Dozey et al.
2001). The ratios of carbon to nitrogen indicated that the source of the contamination was mainly
faeces, decaying mussels and fouling species. In addition, it was found that the biomass of
macrofauna was reduced under the rafts and the community structure and composition had been
altered (Stenton-Dozey et al. 2001).
55
ANCHOR
e n v i r o n m en t a l