Aq Res State Trend
The giant red shrimp stock in the Strait of Sicily is in overfishing status since the current fishing mortality (F
c=1.09) is higher than both F
max and F
0.1. Low level of SSB in the available time series. Considering the high consistency of results with different methods, F
max = 0.70 were proposed as Limit Reference Points (LRP), and F
0.1=0.40 as the Target Reference Points (TRP).
Habitat Bio
Climatic Zone: Temperate. Bottom Type: Soft bottom. Depth Zone: Slope (200 m - 1000 m). Horizontal Dist: Neritic; Oceanic. Vertical Dist: Demersal/Benthic.
Geo Dist
Geo Dist: Straddling between High Seas and EEZ
Exploit
Giant red shrimp (
Aristaemorpha foliacea) is a relevant target species of the Sicilian and Maltese trawlers, caught on the slope ground throughout the year, but landing peaks are observed in summer.
A. foliacea is fished exclusively by otter trawl, mainly in the central–eastern side of the Strait of Sicily, whereas in the western side it is substituted by the violet shrimp,
Aristaeus antennatus. Giant red shrimps are frequently caught together with Norway lobster (
Nephrops norvegicus), large sized deep water pink shrimp (
Parapenaeus longirostris), the more rare violet shrimp (
Aristaeus antennatus) as well as large hake (
Merluccius merluccius). In the last years (2005-2010) mean total yield was 1428 t, ranging from 1287 in 2005 and 2008 to 1951 in 2009. The Sicilian landings are about 98-99% of the total yield.
Bio Assess
Data
Abundance indices from trawl surveys in GSA16 from 1994 to 2010 were used to obtain information on demographic structure of stock at sea. Standardized LFD were converted in age structure by using the Length Frequency Distribution Analysis (LFDA) package. The assessment was carry out only on females (more reliable biological parameters, larger size, and more than 60% of the landing in weight). Biological parameters used for slicing and assessment were: K=0.61; L
inf = 68.9 cm; t
0 = -0.2. Five complete years (2006, 2007, 2008, 2009 and 2010) of length frequency distributions (LFD) from GSA16 commercial landings data (fished in GSA15 as well as GSA16) were available, as well as two years (2009 and 2010) from GSA15. The annual LFD of landing were transformed in age structure of catch as done for the trawl survey data. M-at-age vector (PROBIOM sheet): 0.62; 0.30; 0.23; 0.19; 0.17; 0.16. q vector = estimate: q(Age0)=0.4; q(Age1+)=1.0; q(Age2+)=1.0; q(Age3+);tq(Age4+)=1.0. Data were derived from European DCF data call for GSA15 and 16.
Assess Models
Type: Age-structured
Virtual Population Analysis (VPA)
Methodology
VIT, SURBA (Survey Based Analysis).
Results
Based on VIT, there were 1070 t of spawning stock biomass (SSB) in 2006, 1370 in 2007, 1300 in 2008, 1580 in 2009 and 1260 in 2010. The estimates of absolute recruitment in millions of individuals (age class 1) from VIT analysis in 2006-2010 were 98.1 in 2006, 114 in 2007, 83 in 2008, 118 in 2009 and 123 in 2010.
Assess Models
Type: Size-structured
Yield per Recruit (Y/R)
Results
Y/R results | | Total |
| Current Y/R | 13.51 |
| Maximum Y/R | 14.36 |
| Y/R 0.1 | 13.73 |
| Fcurrent | 0.65 |
| Fmax | 0.42 |
| F0.1 | 15.62 |
| Current B/R | 26.15 |
| Maximum B/R | 38.06 |
| B/R 0.1 | 13.51 |
Sci Advice
For management considerationConsidering F
0.1 as TRP, a reduction ranging between 50 and 60 % of the current F in 2009 and 2010 is recommended. To reach exploitation below F
max, a reduction of current F in the same years ranging between 20 and 40% should be pursued.
Sources
Report of the Working Group on Stock Assessment of Demersal Species. FAO-GFCM Chania, Crete (Greece) 24-29 October 2011. 2011 FAO
http://151.1.154.86/GfcmWebSite/SAC/SCSA/WG_Demersal_Species/2011/WGSA_Demersal-Greece-Report.pdf
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