Linking trawl fleet dynamics and the spatial distribution of exploited species can help to avoid unwanted catches: the case of the NW Mediterranean fishing grounds

García-de-Vinuesa, Alfredo; Solà, Iván; Quattrocchi, Federico; Maynou, Francesc; Demes, Montserrat

doi:10.3989/scimar.04755.17a

Cited by 10 publications

(15 citation statements)

References 27 publications

(41 reference statements)

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“…Monkfish and European hake use crinoid beds as nursery areas. They are primarily discarded because they do not reach the legal minimum size [ 11 , 15 , 25 ]. The commercialization of undersized specimens is illegal, and their revaluation could lead to the creation of a black market that encourages fishermen to catch juveniles, which would only worsen the already poor state of conservation of their stocks in the Mediterranean [ 45 ].…”

Section: Discussionmentioning

confidence: 99%

“…The study area was located in the Northwestern Mediterranean in a trawl fishing ground adjacent to Blanes port ( Figure 1 ), which features a crinoid bed habitat [ 25 , 26 ].…”

Section: Methodsmentioning

confidence: 99%

“…For this reason, discard management is one of the main global challenges to improving the efficiency and sustainability of fisheries [ 23 ]. Trawling discards are mainly composed of commercial species that do not reach the legal minimum size and noncommercial species [ 24 , 25 ], and as in other habitats on the continental shelf, discards in crinoid habitats exceed the total commercial catch by more than half [ 26 , 27 ]. One of the major objectives of the European Union is the gradual implementation of a zero discard practice.…”

Section: Introductionmentioning

confidence: 99%

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The Bioactive Potential of Trawl Discard: Case Study from a Crinoid Bed Off Blanes (North-Western Mediterranean)

et al. 2021

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Although knowledge of the bioactive compounds produced by species inhabiting coastal waters is increasing, little is known about the bioactive potential produced by marine species occupying deeper habitats with high biodiversity and productivity. Here, we investigate about the bioactive potential of molecules produced by species that inhabit the crinoid beds, a poorly known essential fish habitat affected by trawling, wherein large amounts of commercial and noncommercial species are discarded. Based on a trawl survey conducted in 2019, 14% of the 64 species discarded on crinoid beds produce molecules with some type of bioactive potential, including; soft corals (Alcyonium palmatum); tunicates (Ascidia mentula); bony fish, such as horse mackerel (Trachurus trachurus); European hake (Merluccius merluccius); and chondrichthyans, such as small-spotted catshark (Scyliorhinus canicula). In addition, 16% of the discarded species had congeneric species that produce compounds with bioactive potential, indicating that such species might also possess similar types of bioactive molecules. Molecules with antioxidant, antitumour, antihypertensive, and antibacterial properties were the most frequent, which could provide the basis for future research aiming to discover new marine-based drugs and compounds for other human uses. Among all species or genera that produce compounds with bioactive potential, 68% presented medium or high vulnerability to trawling. Results show that the discarded catch contains many species, which produce different bioactive compounds that represent an added-value resource. These results highlight the importance of manage properly crinoid beds, to ensure that species that produce molecules with bioactive potential inhabiting these habitats are protected.

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Section: Discussionmentioning

confidence: 99%

“…The study area was located in the Northwestern Mediterranean in a trawl fishing ground adjacent to Blanes port ( Figure 1 ), which features a crinoid bed habitat [ 25 , 26 ].…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Bioactive Potential of Trawl Discard: Case Study from a Crinoid Bed Off Blanes (North-Western Mediterranean)

et al. 2021

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“…In the case of the CS, species subjected to MCRS often discarded regardless of their size can be mainly low priced sparids like axillary seabream (Pagellus acarne), bogue (Boops boops), and Diplodus spp. (e.g., Garcia-de-Vinuesa et al, 2018). Thus, also in CS, the "iUC grounds" could be shifted towards more coastal waters.…”

Section: Discussionmentioning

confidence: 99%

Marine spatial closures as a supplementary tool to reduce discards in bottom trawl fisheries: Examples from southern European waters

et al. 2020

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Discards is an important issue in fisheries around the world. The spatial management of discards has attracted interest as a potential tool for minimizing the unwanted catch. The aim of the present work was to identify areas with high quantities of bottom trawl discarded catch regarding species subjected to MCRS, in six areas of southern European waters (southern Portuguese waters, Catalan Sea, Ligurian and northern Tyrrhenian Seas, Strait of Sicily, eastern Ionian Sea, and Aegean Sea). Analyses were based on two types of data: (a) the undersized catch of species subjected to MCRS from bottom trawl surveys and (b) the actual discarded catch (including undersized and non-undersized individuals) of species subjected to MCRS from commercial bottom trawling. Geostatistical analysis techniques were applied to the first type of data and Generalized Additive Models using environmental variables were applied to the second one. Subsequently, areas that persistently presented high quantities of discarded catch (i.e., "iDC grounds") or undersized catch (i.e., "iUC grounds") were identified and mapped. The "iDC grounds"/"iUC grounds" were located either over the slope or within the continental shelf and over marine plateaus, largely depending on the main target species of each fishery. Next, the overlap of "iDC grounds"/"iUC grounds" with the existing Fisheries Restricted Areas (FRAs) and the proposed Marine Protected Areas (MPAs) was estimated aiming to explore how spatial closures could contribute to the reduction of bottom trawl discarded catch/undersized catch. Certain spatial closures were more effective in the Central Mediterranean and others to the Eastern Mediterranean. The overlapping of existing FRAs with "iDC grounds"/"iUC grounds" did not exceed 24 % in any study area, whereas proposed MPAs, like the CIESM Marine Peace Parks, reached up to 90 % for the same study area.

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“…Technical measures have been in place for decades in an attempt to avoid catching undersized animals in the Mediterranean Nephrops fisheries, including an MCRS of 20 mm in carapace length (CL) and minimum trawl cod-end mesh sizes of 40 mm (square-mesh) or 50 mm (diamond) (Council Regulation (EC) No., 1967; GFCM/29/ 2005/1). However, these control measures have not been not fully effective because substantial numbers of undersized Nephrops between 15 and 20 mm CL continue to be caught and discarded, contravening the LO that has been in place since 1st January 2019 (García -de-Vinuesa et al, 2018). Furthermore, the size of maturity for Nephrops in the Mediterranean Sea is between 30 and 36 mm in CL (Orsi Relini et al, 1998), which is much larger than the MCRS.…”

Section: Introductionmentioning

confidence: 99%

Seasonal variation in the survival of discarded Nephrops norvegicus in a NW Mediterranean bottom-trawl fishery

et al. 2020

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The landing obligation in the revised European Union Common Fisheries Policy allows for exemptions to obligatory landing of the entire catch for species for which "high survival" of discards can be demonstrated. Nephrops norvegicus is an important target species in many fisheries across Europe in the Mediterranean Sea, NE Atlantic Ocean and North Sea. Historically, Mediterranean fisheries have had a high discard rate of small-sized Nephrops, and it is suspected that this unwanted component of the catch may have a high survival potential that is comparable to those of other EU fisheries, where survival rates of up to 0.56 have been demonstrated. However, to date, no investigations have confirmed a high discard survival rate for Nephrops in the Mediterranean Sea. Furthermore, the environmental, technical and biological characteristics that could affect Nephrops survival have been shown to be substantially different from those in the survival assessments conducted in the NE Atlantic and the North Sea. To address this knowledge gap, this study was conducted to determine the survival of Nephrops discarded from trawls in the Mediterranean Sea. The survival and vitality status of the discarded Nephrops removed from trawl catches were monitored onboard and for 14 days in the laboratory. The results showed seasonality in survival, with the highest survival rate in winter (0.74; CI: 0.7−0.78), lower survival in spring (0.36; CI: 0.31−0.41) and the lowest survival in summer (0.06; CI: 0.04−0.09). Survival was monitored to the asymptote in all cases, and season and vitality status were shown to have statistically significant relationships with survival.

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Linking trawl fleet dynamics and the spatial distribution of exploited species can help to avoid unwanted catches: the case of the NW Mediterranean fishing grounds

Cited by 10 publications

References 27 publications

The Bioactive Potential of Trawl Discard: Case Study from a Crinoid Bed Off Blanes (North-Western Mediterranean)

The Bioactive Potential of Trawl Discard: Case Study from a Crinoid Bed Off Blanes (North-Western Mediterranean)

Marine spatial closures as a supplementary tool to reduce discards in bottom trawl fisheries: Examples from southern European waters

Seasonal variation in the survival of discarded Nephrops norvegicus in a NW Mediterranean bottom-trawl fishery

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