4.6 Interactions among aquaculture, capture fisheries and the environment in coastal lagoon management

4.6.1 Competition for space (location of aquaculture facilities in fishing grounds, existence of “planning management” for lagoon areas, etc.)

Some conflicts between the professional fishers and farmers against the non-registered ones or against the tourists, or against the people coming from different regions can exist. In the past, they have been sometime very important, mainly in the Thau lagoon, but nowadays it can be said that the situation is calm.

4.6.2 Organic input from aquaculture activities

The main interaction between fishery and aquaculture is due to the presence of large amounts of shellfish allowing for the development of a massive benthos, while organic enrichment from biodeposition changes the specific composition of soft-bottom benthos. In the deeper areas where summer thermoclines limit oxygen transfer from surface water, the organically enriched substrate induces oxygen depletion and ammonium and nitrogen sulfide accumulation in the water column. This ecosystem dysfunction kills benthic populations, and sometimes reaches pelagic populations and affects at the same times the shellfish farming and the fisheries
economy.