Western Mediterranean Sea
Abstract: Data used to produce figures come from the STECF working group on Mediterranean and Black Sea. Please note that time series might be incomplete for some countries/indicators.
Landings
The Western Mediterranean case study focuses on two contrasting areas in terms of the ecosystem productivity, exploitation pattern, and types and rates of discards:
the French and Spanish Gulf of Lions and the Balearic Archipelago. These areas encompass two different geographical subareas (GSAs), defined by the General Fisheries Commission for the Mediterranean
(GFCM) for the assessment and management of Mediterranean stocks: 1) Balearic Islands
(GSA 5); and 2) Gulf of Lions (
GSA 7).
The Gulf of Lions is the most productive area in the western Mediterranean owing to the winter upwelling and the discharges of rivers, whereas the Balearic Islands constitute an especially oligotrophic area within the general oligotrophy of the Mediterranean.
Hake and red mullet from the Gulf of Lions are shared stocks exploited by the French and Spanish fleets. The French trawler fleet is the largest both in number of boats and landings (41% and 72%, respectively). The second largest fleet is the French gillnetters (41 and 14% respectively), followed by the Spanish trawlers (11 and 8%, respectively), and the Spanish long-liners (6 and 6%, respectively).
Area landings overview is displayed in the Area factsheet.
In DiscardLess, we focus on bottom trawl fisheries.
Proportion of landings in each rectangle
Landings 2014
       [STECF MED & BS data (2015)] |
Trends in landings by gears
|
[STECF MED & BS data (2015)] |
The French trawl fleet is composed of 70 vessels from 18 to 25 m length, 61 of which are based on the continental coast and the remaining ones in Corsica. This fleet is relatively homogeneous, half of the trawlers of 18-24 m length and the other half of 24-25 m length. The number of trawlers decreased from 134 vessels in 2005 down to 100 units in 2010 and then to 70 vessels in 2014; altogether a reduction of 50% of the fleet size in less than 10 years. The activity of the French trawler fleet is restricted to the shelf (<200m) mostly due to the fishing trip duration being limited to under 14h per day. They are a mixed fishery whose catches are very diversified and whose revenue is spread over 30 different species. The Spanish fleet is composed of about 10 trawlers and, on the contrary, is mostly operating at deeper shelf and mostly target European hake (Merluccius merluccius) and red mullets (Mullus barbatus).
Average Landings by gears
Year 2014
|
[STECF MED & BS data (2015)] |
Trends in landings
By vessel length
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[STECF MED & BS data (2015)] |
By countries
|
[STECF MED & BS data (2015)] |
Average Landings by countries
Year 2014
|
[STECF MED & BS data (2015)] |
In the Balearic Islands (western Mediterranean), commercial trawlers use up to four different fishing tactics, which are associated with the shallow and deep continental shelf, and the upper and middle continental slope. Vessels mainly target striped red mullet (Mullus surmuletus) and European hake (Merluccius merluccius) on the shallow and deep shelf respectively. However, these two target species are caught along with a large variety of fish and cephalopod species. The Norway lobster (Nephrops norvegicus) and the red shrimp (Aristeus antennatus) are the main target species on the upper and middle slope respectively. The Norway lobster is caught at the same time as a large number of other fish and crustacean species, but the red shrimp fishery is the only Mediterranean bottom trawl fishery that could be considered monospecific.
Historically, the number of fishing vessels has remained very low in the Balearic Islands compared to nearby areas. The number of trawlers doubled in Mallorca from 35 to 70 units between 1965 and 1977, but has decreased progressively since then to the 28 current vessels. In the rest of the Balearic Islands, the current number of trawlers is even lower: 7 in Menorca, 8 in Ibiza and 2 in Formentera. These values are clearly very far from the total number of vessels in GSA 6 (northern Spain), for instance, where the fleet has decreased from 810 trawlers in 1998 to the current 550 units.
Average Landings by species
Year 2014
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[STECF MED & BS data (2015)] |
Trends in landings by species
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[STECF MED & BS data (2015)] |
Discards
Reasons for discarding are highly variable and they can be driven by economic, sociological, environmental or biological factors. These factors often act together; it is quite difficult to separate them, especially in multispecies fisheries. In the Mediterranean, discards are characterised by extremely high species diversity with a high percentage of non-commercial catch and high variability in total discard rate due to seasonality.
Although the reported discard rate appeared very low in official data, the average discard rates during 2011-2014 for the French OTB fleets in the Gulf of Lions were about 25% and varies with the different species, being very high for small pelagics such as Engraulis encrasicolus and Sardina pilchardus, but very low for high-value species such as M. merluccius and Sparus aurata as minimum landing sizes are often ignored for those high-value fish. The 2012-2014 average discard biomass rates of the Spanish OTB fleet from the Gulf of Lions was in general lower than 10% for most of the species subjected to a regulation, except again for the case of small pelagic species like E. encrasicolus and S. pilchardus. The 2012-2014 average discard biomass rates for the Balearic Islands were in general lower than 10% for most of the species subjected to a regulation, except for three species (Trachurus trachurus, T. mediterraneus and S. pilchardus). In both study areas, small pelagic species are by-catch species for the bottom trawl fleet and their importance is highly variable, both in terms of catches (their catchability shows important oscillations) and in terms of their final destination (they are landed or discarded depending on different factors, including market interest).
Catches (Landings+Discards)
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[STECF MED & BS data (2015)] |
Disclaimer : Following graphs are made using discards rates at high spatial level and the landings at statistical rectangle level as raising factor. We assume that it's not the more statistically consistent way to proceed. However we consider that, with available data, it's a first step to use the data.
Discards by species
Year 2013
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[STECF MED & BS data (2015) for landings and National Data for discards rate] |
Year=2014
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[STECF MED & BS data (2015) for landings and National Data for discards rate] |
Discards by Species for most important gears (year=2014)
Second Gear ()
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[STECF MED & BS data (2015) for landings and National Data for discards rate] |
Third Gear ()
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[STECF MED & BS data (2015) for landings and National Data for discards rate] |
First Gear (in terms of total discards) (OTB)
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[STECF MED & BS data (2015) for landings and National Data for discards rate] |
Trends in discards by Country (5 most important countries in Landings)
Total Discards
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[STECF MED & BS data (2015) for landings and National Data for discards rate] |
Discards ratio (Discards/(landings+discards))
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[STECF MED & BS data (2015) for landings and National Data for discards rate] |
Trends in discards by Gear (5 most important Gear in Landings)
Total Discards
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[STECF MED & BS data (2015) for landings and National Data for discards rate] |
Discards ratio (Discards/(landings+discards))
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[STECF MED & BS data (2015)for landings and National Data for discards rate ] |
Trends in discards by Gear (5 most important species in Landings)
Total Discards
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[STECF MED & BS data (2015) for landings and National Data for discards rate] |
Discards ratio (Discards/(landings+discards))
|
[STECF MED & BS data (2015)] |
En savoir plus
Citation :
Fiche Western Mediterranean Sea, Author(s) : Sandrine Vaz et Toni Quetglas
DiscardLess Atlas [on line]. 2017. Guitton J., Ulrich, C., Vermard Y., Afonso P., Andonegi E., Argyrou I., Calderwood J., Fauconnet L., Quetglas A., Morato T., Prellezo R., Robert M., Savina-Rolland M., Triantaphyllidis G., Vaz S.
http://www.discardless.eu/atlas/
