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| Marine Resource Fact Sheet |
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| Common sole - Adriatic Sea, 2007 |
 | Solea solea - Adriatic Sea |
| | Owned by | General Fisheries Commission for the Mediterranean (GFCM)
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| Main Descriptors | Considered a single stock: Yes
Spatial Scale: Sub-Regional
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| Considered a single stock: A group of individuals in a species occupying a well defined spatial range independent of other stocks of the same species. It can be affected by random dispersal movements and directed migrations due to seasonal or reproductive activity. |
| Spatial Scale: Spatial scale contains a standard term such as Global, Regional (e.g. for the whole Atlantic), sub-regional (e.g. for a part of the Atlantic), national, local (for sub-national levels). |
| Considered a management unit: An aquatic resource or fishery is
declared as [Fishery] Management Unit if it is
effectively the focus for the application of selected
management methods and measures, within the broader
framework of a management system. According to the FAO
Glossary for Responsible Fishing, "a Fishery Management
Unit (FMU) is a fishery or a portion of a fishery
identified in a Fishery Management Plan (FMP) relevant
to the FMP's management objectives." FMU's may be
organised around fisheries biological, geographic,
economic, technical, social or ecological dimensions ,
and the makeup and attribute of a fishery management
unit depends mainly on the FMP's management
objectives. |
| Jurisdictional distribution: Jurisdictional qualifier (e.g.
"shared", "shared - highly migratory") of the aquatic
resource related with its spatial distribution. |
| Environmental group: Classification of the aquatic
resource according to the environmental group (e.g.
pelagic invertebrate, or demersal fish) to which the
species belong. |
| | | | | | Habitat and Biology Climatic zone: Temperate. Bottom type: Soft bottom. Depth zone: Coastal 0 50m; Shelf 50 200m. Horizontal distribution: Estuarine; Neritic. Vertical distribution: Demersal/Benthic. Geographical Distribution Jurisdictional distribution: Unspecified Water Area Overview Spatial Scale: Sub-Regional Geo References  | | Distribution of Common sole - Adriatic Sea
| GFCM geographical sub-areas | 17: Northern Adriatic |
| | | | | | Other georeferences
| FAO Fishing Statistical Division Areas | 37.1.2: Gulf of Lions |
| | | | | | Intersecting Major FAO areas and LME areas |
The following area codes have been found as intersecting the distribution of Common sole - Adriatic Sea Resource Structure Considered a single stock: Yes Exploitation Sole ( Solea solea) is one of most important target species of rapido trawl and set net fleets in GSA 17. The stock is shared between the Adriatic countries (Italy, Croatia and Slovenia). The Italian fleets exploit this resource with rapido trawl and set nets (gill nets and trammel nets), while only trammel net is used in the countries of the eastern coast. More than 90% of catches come from the Italian side.
Landings fluctuated between 1,000 and 2,300 t in the period 1996-2006 (data source: FAO-FishStat and IREPA-SISTAN time series).
The fishing effort applied by the Italian rapido trawlers gradually increased from 1996 to 2005, and slightly decreased in the last years. Information on Operational Units exploiting this resource will be soon available at the following link: GSA 17 Common Sole (Solea solea)Assessment Assessment Model Type: Age-structured Virtual population analysis (SVPA) Methodology The assessment of sole stock was performed for the period 2005-2007 by means of VPA Separable tuned with CPUEs from commercial fleets and abundant indexes from rapido trawl surveys.
Abundance and biomass indexes from rapido trawl surveys were computed using ATrIS software (Gramolini et al., 2005) which also allowed drawing GIS maps of the spatial distribution of the stock, of spawning females and of juveniles. Underestimation of small specimens in catches due to the gear selectivity was corrected using the selectivity parameters given by Ferretti and Froglia (1975).
VPA flow was processed by means of an Excel spreadsheet using catch-at-age from commercial landings, assuming a natural mortality vector (Ma) from Caddy’s method (1991) (PROBIOM Excel spreadsheet; Caddy and Abella, 1999) and abundance-at-age (start year) from survey data. Results Analytical results and survey indexes showed similar patterns for total biomass, SSB and recruits. The total biomass and SSB remained practically constant from 2005 to 2007, while a low recruitment occurred in 2006. The SSB pattern over the three years is likely related to the fact that the main spawning area (north-eastern Adriatic Sea) is only partially exploited by both the Italian rapido trawlers and the Croatian set netters.
Fbar estimated for the most exploited age classes (0+, 1, 2) decreased in the three years reaching the minimum of 0.52 in 2007. This Fbar pattern was due to a decrease of the fishing effort by the main Italian rapido trawl fleets in GSA 17 in terms of both number of vessels and fishing time, as well as to the switching of rapido trawlers towards other resources (e.g. gastropods and bivalves).
More than 40% of landed soles, corresponding to about 20% of landed biomass, have a TL<20 cm (Minimum Landing Size; EC 1967/2006). Therefore, the Y/R analysis applied with the age at first capture of 0.7 (around 16 cm TL) showed that an Fbar value of 0.52 is still higher than Fmax (0.46) and that the resource is fully exploited/overexploited.
Taking into account that the exploitation is mainly orientated towards juveniles and the success of recruitment seems to be related to environmental conditions, a high risk of stock depletion might exist in the case of both unsustainable level of fishing effort and scarce recruitment.
Assessment Model Type: Size-structured Yield per recruit analysis (Y/R) Methodology Yield-per-recruit (Y/R) analysis (Yield version 1.0, MRAG: Branch et al., 2000) was applied to estimate the reference points. Results The Y/R analysis applied with the age at first capture of 0.7 (around 16 cm TL) showed that an Fbar value of 0.52 is still higher than Fmax (0.46) and that the resource is fully exploited/overexploited.
Taking into account that the exploitation is mainly orientated towards juveniles and the success of recruitment is strictly related to environmental conditions, a high risk of stock depletion might exist in the case of both unsustainable level of fishing effort and scarce recruitment. Scientific Advice For management considerations- A further reduction at least of 10% to reach the Fmax and around 50% to reach F0.1 of the ’ fishing pressure applied by rapido trawlers (in terms of number of vessels and/or fishing time) would be recommended.
- A two–months closure for rapido trawling inside 6 nm offshore along the Italian coast, after the biological fishing stop (August), would be advisable to reduce the portion of undersized specimens (mainly YOY);
- Despite of the mesh opening used by the Italian rapido trawlers is larger (48 mm or more) than the legal one, the catches usually include a noticeable portion of undersized specimens. As no specific studies on rapido trawl selectivity are available at present, it is not sure that the adoption of a larger mesh size could correspond to a decrease of illegal catches.
- The safeguard of spawning areas (both in spatial and temporal terms) to prevent a possible future exploitation might be crucial for the sustainability of the Adriatic sole stock.
- A set of specific rules for rapido trawl fishery would be advisable (e.g.: size and number of gears, mesh size, towing speed).
Management Management Advice Scientific advices for management consideration formulated by SCSA have been adopted by SAC. Advices and comments by SAC- Provide fishing effort level
- Provide the period of the temporal closure and location of the area which should be protected
Biological State and Trend Exploitation state: OverexploitedExploitation rate: High fishing mortality
Abundance level: Low abundance The fishery is being exploited above a level that is believed to be sustainable in the long term, with no potential room for further expansion and a high risk of stock depletion/collapse Source of information “Stock assessment of Common sole (Solea solea) in the Geographical Sub-Area 17 (Northern Adriatic). Stock Assessment Form” . G. Fabi, O. Giovanardi, F. Grati, I. Isajlovič, D. Pehar, P. Polidori, S. Raicevich, G. Scarcella, N. Vrgoč FAO-GFCM September 2008 2008 FAO  . “Report of the eleventh session of the SCIENTIFIC ADVISORY COMMITTEE” FAO-GFCM Marrakech, Morocco, 1−5 December 2008 2008 FAO  . |
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