Looking for a Simple Assessment Tool for a Complex Task: Short-Term Evaluation of Changes in Fisheries Management Measures in the Pomo/Jabuka Pits Area (Central Adriatic Sea)

Abstract

A Before–Intermediate–After Multiple Sites (BIAMS) analysis, namely a modified version of the Before–After–Control–Impact (BACI) approach, was used to evaluate the possible effects of fishery management measures implemented in the Pomo/Jabuka Pits area, a historically highly exploited ground for Italian and Croatian fisheries, whose impact may have contributed over the years to the modification of the ecosystem. Since 2015, the area was subject to fishing regulations changing the type of restrictions over time and space, until the definitive establishment in 2018 of a Fishery Restricted Area. These changes in the regulatory regime result in complex signals to be interpreted. The analysis was carried out on abundance indices (i.e., kg/km2 and N/km2) of five commercially or ecologically relevant species, obtained in the period 2012–2019 from two annual trawl surveys. BIAMS was based on the selection of a Closure factor, declined in three levels (i.e., BEFORE/INTERMEDIATE/AFTER) and accounting for regulation changes in time, and on three adjacent strata (i.e., “A”, “B”, and “ext ITA”) a posteriori determined according to the latest regulations. BIAMS allowed us to identify early effects (i.e., changes in abundances), overcoming the unavailability of a proper independent control site; furthermore, the selection of adjacent strata allowed the inference of possible interactions among them.

Changes in Abundance and Distribution of the Sea Pen, Funiculina quadrangularis, in the Central Adriatic Sea (Mediterranean Basin) in Response to Variations in Trawling Intensity

“…The density (n/m 2 ) of colonies per minute was calculated using the number of individuals of F. quadrangularis counted divided by the swept area. In order to assess the F. quadrangularis density variation as a potential effect of the management measures implemented over time and space, an approach was adopted that is very similar to that used in Chiarini et al [55]; in the latter study, in fact, a short-term evaluation of changes in fisheries management measures occurring in the Pomo/Jabuka Pits Area was carried out through a Before-Intermediate-After Multiple Sites (BIAMS) approach (a variant of the classic "before-after-control-impact" model design also adopted in an attempt to compare contiguous strata with different characteristics overcoming the unavailability of an adequate independent control site). To facilitate a possible comparison with the results obtained in the area for other species, within this study, only UWTV data collected from 2012 onward were considered; therefore, 8 UWTV surveys conducted in the period 2012-2019 (except for 2018) were taken into account.…”

“…Also possibly linked to climate change, a crustacean species shift also occurred in the area: the squat lobster Munida intermedia (Milne-Edwards and Bouvier, 1899), was replaced by Iridonida speciosa (von Martens, 1878) (previously known as Munida speciosa), first observed in 2003 [54]. Another gadoid species dwelling in the area, the blue whiting Micromesistius poutassou (Risso, 1827), was reported to experience fluctuations in abundance over time, probably as a result of environmental variations and fishing exploitation [55]. Therefore, the Pomo/Jabuka Pits represent a VME and an EFH worthy of implementation of appropriate management measures aimed at protecting the demersal fish stocks, enhancing the densities of organisms in terms of biomass and abundance, and protecting possible VMEs while ensuring the sustainable exploitation of the main resources [37,56].…”

“…Therefore, the Pomo/Jabuka Pits represent a VME and an EFH worthy of implementation of appropriate management measures aimed at protecting the demersal fish stocks, enhancing the densities of organisms in terms of biomass and abundance, and protecting possible VMEs while ensuring the sustainable exploitation of the main resources [37,56]. For this reason, a series of management measures were implemented in the area over time [55,57], which led to the establishment, in 2017, of a Fishery Restricted Area (FRA) by the General Fisheries Commission for the Mediterranean (GFCM, [48]). The FRA is divided into three zones: "A," which is closed to all fishing activity, "B," where bottom trawling is regulated with licenses and a number of fishing days (two days allowed per licensed vessel per week, fishing vessels using twin bottom otter trawls can fish one day per week), and fishery is banned from 1 September to 31 October, and zone "C," where trawling is permitted through licenses on Saturdays and Sundays (from 5.00 am to 10.00 pm), whereas vessels fishing with bottom-set nets, set longlines and traps can fish from Monday 05.00 am till Thursday 22.00 pm, and fishing is also banned from 1 September to 31 October (fishing activity with purse seiners and pelagic trawlers targeting anchovy or sardine is prohibited in the FRA; Figure 1).…”

The potential effects of COVID-19 lockdown and the following restrictions on the status of eight target stocks in the Adriatic Sea

“…As regards hake, the official stock assessments over recent years were describing an increasing biomass trend from 2017, when the Pomo pit FRA was established. The biomass increase slightly improved in 2020, suggesting that the effect of the COVID pandemic on hake stock was negligible when compared to the effectiveness of the FRA (Chiarini et al, 2022). Red mullet was an exception; it is a target of OTB, and a large fishing mortality decrease was observed.…”

“…Another management aspect for demersal fisheries that might have interacted with COVID restrictions is GFCM/41/2017/3, which defines a Fishery Restricted Area (FRA) in the Pomo/ Jabuka pit, a heavy exploited and productive area. The Pomo FRA is deemed to protect essential fish habitat for European hake and Norway lobster, with the first experiencing a positive biomass trend over recent years (Chiarini et al, 2022). Considering that the effective fishing effort reduction in the Pomo area was limited to a few weeks (FAO, 2021d) and that this area is not fished by TBB (Armelloni et al, 2021;Coro et al, 2022c), we assume a negligible interaction of this management measure with COVID-related restrictions.…”