Preprint volume - SIBM

Pre-print Volume –Posters
NECTON AND FISHERY COMMITEE
Froglia, 1981. An average size greater than 25 mm was obtained with sieves ≥21.5
mm, but the presence of undersized clams was however detected, its importance
varying according to the different fishing grounds. As it seems not feasible to avoid the
catch of undersized clams, in order to comply with the EC Reg. 1967/06, a “number
per kilogram” system, like that in use for anchovies and sardines, can be proposed.
Taking into account the average weight at different sizes (not shown), as well as the 21
mm sieve selectivity and the weight loss before sale, it could be established in 220
specimens per kg the allowed landing value. Another indication could be the use of
sieves with 21.5 mm minimum holes. Digital image acquisition and processing is
sufficiently precise (Vaccarella, 1998) and fast, allowing the processing of
approximately 20,000 clams per person per day.
Tab. 1- Summary results of caught clams. CFS = cumulative frequency size.
Riassunto dei dati delle vongole catturate. CFS = taglia della frequenza cumulata.
Haul Sieve
mm
Gross
weight
kg
Discard
kg
Net
weigth
kg
N N/kg Min
size
mm
Mean
size
mm
Max
size
mm
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
325
CFS
25%
mm
CFS
50%
mm
CFS
75%
mm
1 20.0 12.400 0.178 12.222 3044 249 19.2 23.9 27.8 23.5 23.9 24.4
2 20.0 11.400 0.115 11.285 2715 241 19.9 23.7 27.9 23.2 23.7 24.2
3 20.0 8.500 0.241 8.259 2029 246 17.7 23.5 28.3 23.0 23.6 24.0
1 20.5 10.510 0.110 10.400 2509 241 16.2 24.2 30.0 23.6 24.4 25.0
2 20.5 9.690 0.170 9.520 2304 242 18.9 23.9 27.7 23.2 24.0 24.7
3 20.5 9.520 0.120 9.400 2190 233 18.3 24.2 27.7 23.7 24.3 24.9
1 21.0 12.300 0.156 12.144 2639 217 20.0 25.0 32.3 24.4 25.0 25.6
2 21.0 11.800 0.085 11.715 2492 213 22.3 25.0 30.3 24.4 24.9 25.5
3 21.0 10.200 0.226 9.974 2140 215 20.8 24.8 31.7 24.2 24.8 25.4
1 21.5 11.700 0.200 11.500 2431 211 19.4 25.3 33.7 24.6 25.5 26.2
2 21.5 9.220 0.100 9.120 1807 198 20.1 25.7 29.5 25.1 25.8 26.4
3 21.5 9.260 0.110 9.150 1850 202 19.3 25.3 30.3 24.7 25.4 26.1
1 22.0 13.300 0.136 13.164 2348 178 23.6 26.8 37.0 26.0 26.7 27.4
2 22.0 11.500 0.075 11.425 2074 182 22.7 26.5 32.6 25.7 26.4 27.2
3 22.0 11.400 0.163 11.237 1943 173 23.0 26.9 34.1 25.9 26.8 27.8
1 23.0 7.000 0.070 6.930 1069 154 23.3 28.2 35.0 27.3 28.1 28.8
2 23.0 8.380 0.050 8.330 1333 160 24.5 27.8 34.2 27.1 27.7 28.4
3 23.0 12.660 0.110 12.550 2012 160 24.6 27.7 34.4 26.9 27.6 28.4
References
FROGLIA C., GRAMITTO M.E. (1981) – Considerazioni sulla selettività dei dispositivi di
setacciatura utilizzati nella pesca delle vongole (Venus gallina L.). Quad. Lab. Tecnol. Pesca, 3
(1): 37-46.
RASBAND W.S. (2010) – IMAGEJ U.S. National Institutes of Health, Bethesda, Maryland, USA.
http://rsb.info.nih.gov/ij/
VACCARELLA R. (1998) – Length estimation of baby clam (Chamelea gallina) by using an image
analysis system. Biol. Mar. Mediterr., 5 (1): 855-858.