Spatial fishing restrictions benefit demersal stocks in the northeastern Mediterranean Sea

Abstract

The multi-level benefits that marine organisms gain when protected from fishing are well acknowledged. Here, we investigated the effects of a 40-year trawling ban on the status of targeted and non-targeted marine species within a major fishing ground in the northeastern Mediterranean Sea (Thermaikos Gulf, Aegean Sea). Biomass and somatic length of fish and invertebrates (six commercial and three non-commercial demersal species) were measured in three areas of varying fishing pressure, depending on the temporal and spatial operational regimes of fishing vessels. The positive effects of fishing restrictions on the studied demersal stocks were clearly revealed, as the commercial fish species exhibited higher biomass in the intermediate and low pressure areas, as well as increasing maximum and mean total length (and other length indicators) with decreasing fishing effort. The mean total length of non-commercial species generally did not differ among areas, except for species caught and discarded at high rates. The present study shows that fishing does alter the population structure and biomass of commercial demersal species, and that fishing restrictions greatly contribute to improving the status of demersal populations within the restricted areas by providing a refuge for large individuals and their important contribution to the gene pool.

Current and potential contributions of the Gulf of Lion Fisheries Restricted Area to fisheries sustainability in the NW Mediterranean Sea

“…Our results also showed that the establishment of specific objectives should be the main aspect of implementing a restricted area to fisheries [74,75] and managers should focus on indicators related to the overall objective of this protection [76]. The CoSEGoL FRA was focused on demersal species [37], and our study showed that reducing fishing effort in the CoSEGoL FRA could benefit demersal species, in accordance to findings by other studies [18]. Regarding target species, biomass and catch-based indicators changed under different RCP scenarios in 2040, and thus climate change predictions under multiple scenarios should be considered for management purposes in the future [77].…”

“…FRA effectiveness and compliance was measured through changes in ecological and keystone species indicators to discern expected biomass increases according to theory [59]. For example, a positive trend in the biomass of a targeted species is to be expected in a FRA after several years of its protection [18]. In addition, changes in mixed trophic impacts (MTI) from the industrial fleets were examined to quantify the direct and indirect impact of each fleet on functional groups, their potential competitions and trade-offs.…”

“…By 2020 the 10% of the Mediterranean Sea should be protected [17] to ensure the improvement of the status of fish stocks and fisheries. Well established and effective FRAs could contribute to increase the protected surface in the Mediterranean Sea [18,19]. Currently, official spatial protection in the Mediterranean Sea covers more than 10% of its surface [20], although most of these areas are poorly protected or unprotected [21] and the surface of fully protected areas is around 0.04% [22].…”

Ecosystem Models and Effort Simulations of an Untrawled Gulf in the Central Aegean Sea

“…For that reason, in some cases, fishing effort restrictions, the main fisheries management enforcement tool in the Greek Seas (Stergiou et al, 2016), should be complemented with spatial effort closures in essential fish habitats. Spatial effort constraints through the establishment of marine protected areas or spatial fisheries restrictions (Dimarchopoulou et al, 2018) may also have beneficial results in terms of biomass increase and ecosystem function (Fouzai et al, 2012;Abdou et al, 2016).…”

Evidence for spatiotemporal shift in demersal fisheries management priority areas in the western Mediterranean

“…Marine protected areas are a promising strategy for fisheries management (Hilborn et al 2004; Rodríguez-Rodríguez, Rodríguez, Malak, Nastasi, & Hernández 2016). In the past, there was a distinction between marine protected areas that aimed for the protection of biodiversity and those that aimed for fisheries management, but currently it is argued that they provide both biodiversity and fishery benefits (Dimarchopoulou, Dogrammatzi, Karachle, & Tsikliras 2018; Fraschetti et al 2018; Gell & Roberts 2003b 2003a; Petza et al 2017; Roberts, Hawkins, & Gell 2005). Fisheries restricted areas (FRA) are a particular case of marine protected areas where all or certain fishing activities are temporarily or permanently banned or restricted to improve stock status and long term sustainability (Jonas, Barbuto, Jonas, Kothari, & Nelson 2014; Petza et al 2017).…”