Spatial Management Units as an Ecosystem-Based Approach for Managing Bottom-Towed Fisheries in the Central Mediterranean Sea

Abstract

Marine ecosystems are being continually impacted by human activities and, among these, fisheries have been one of the most damaging. Fisheries modify the structure and functioning of food-webs through biomass removal and physical damage to the seabed, leading to loss of biodiversity and ecosystem services provided by the oceans. The ecosystem-based approach to fisheries is considered the most efficient way to achieve the goal of sustainable use of marine resources while allowing for biodiversity protection. The Strait of Sicily is a biologically important area of the central Mediterranean Sea characterized by high habitat complexity and rich biodiversity, however, due to the multispecific nature of local fisheries and weak implementation of the adopted management plans, this region is particularly vulnerable. We used fishery independent time series (1994-2016) to identify the main demersal assemblages and map their spatial distribution. The pressure of fishing effort on each of these defined assemblages was then quantified in order to evaluate the impact of bottom trawling on demersal communities. Our results showed four spatially distinct and temporally stable assemblages of the Strait of Sicily. These have a clear spatial distribution, different species composition and biodiversity values and are driven primarily by environmental gradients (i.e., mainly depth and, to a lesser extent, surface salinity). The demersal assemblages were subsequently grouped in homogeneous areas characterized by specific communities of commercial and non-commercial species and response to trawling impacts. These areas are proposed as Spatial Managements Units to evaluate and manage demersal mixed fisheries, while also considering biodiversity conservation in the central Mediterranean Sea.

What is in our seas? Assessing anthropogenic litter on the seafloor of the central Mediterranean Sea

“…In fact, they represent an obstacle to bottom trawling and can cause the damage or loss of fishing gear, the recovery of which can be difficult when working in deep water. This could explain the relatively high density of fishing nets found in the FADs area which overlaps the fishing grounds of giant red shrimp (an economically important species in the area) located on the west of Maltese islands (Russo et al, 2019;Lauria et al, 2020). These fishing grounds are exploited by distant trawlers belonging to the Mazara del Vallo port, which generally undertake long fishing trips (15-30 days) and hence may be responsible for dumping other typologies of litter.…”

“…Another aspect is the potential risk associated to the degradation product of plastic items, i.e. microplastics (plastic fragments below 5 mm in size) which are ingested by zooplankton and may be transferred through the entire marine food web up to humans (Thompson et al, 2009;Cole et al, 2011;Lusher et al, 2017). Even social and economic damages are associated to marine litter mainly due to the loss of the aesthetic value and related ecosystem services of marine landscapes littered with anthropic waste (Xanthos & Walker, 2017;Maes et al, 2019).…”

Mesoscale productivity fronts and local fishing opportunities in the European Seas

“…The present study provides further evidence that a local estimate of productivity available to fish is useful for spatialized management measures to mitigate regional or local over-exploitation. For instance, at the regional scale, this information could complement the approach of Lauria et al, (2020) in the region of the Sicily Strait, which is associated with mixed fishing grounds, by optimizing the ratio between the productivity of fisheries resources and the good ecological status of communities. At a local scale, this information could be used to redirect fishing effort from over-exploited to underutilized areas (Bastardie et al, 2019).…”

Spatial analysis of demersal food webs through integration of eDNA metabarcoding with fishing activities

“…We examined an area historically exploited by fisheries: the Strait of Sicily (SoS). The SoS is a biologically important area of the central Mediterranean Sea characterised by high habitat complexity and biodiversity (Di Lorenzo et al, 2018;Russo et al, 2019), which notably suffers from ecological alterations (Agnetta et al, 2019;Lauria et al, 2020).…”