FSAM 2010 - Fish Sampling with Active Methods September 8-11, 2010, Ceske Budejovice, Czech Republic Evaluation of the efficiency of bottom traps and trammel net in capturing cuttlefish Sepia officinalis in Abruzzi waters (Adriatic Sea) Giansante C.1, Castriota L. 2, Milillo G.S. 1, Salini R. 1, Andaloro F. 2, Ferri N. 1 1 Istituto Zooprofilattico Sperimentale dell’ e del Molise “G. Caporale” (IZS A & M), Via Campo Boario, 64100 - corrispondenza: [email protected] 2 Institute for Environmental Protection and Research (ISPRA), Via Salvatore Puglisi 9, 90143 Palermo,

A research project aiming at evaluating the population consistency of the cuttlefish Sepia officinalis was carried out in 2008 along the coasts of the Abruzzi (Italy), in the Adriatic Sea. In this area, at the end of winter (March-April) cuttlefish migrate from cold, deep waters toward warmer coastal waters, where they reproduce. Small-scale cuttlefish fishery is permitted in this area from 15 March to 30 September. During this period, two different sampling gears, bottom traps and trammel nets, were used in five stations to test their efficiency in capturing cuttlefish. The caught specimens were counted, measured and weighed, and their sex and sexual stage determined. The results showed that bottom traps were always more efficient than trammel nets. During the first months of migration (March-April) a higher percentage of large males was recorded, followed by catches of females and smaller males in 1. Introduction later periods. Bottom traps also proved to be a valid sampling method for the octopus Octopus vulgaris, which was 1. Introduction The cuttlefish Sepia officinalis is a demersal species widely found during the entire study period and represented the second most abundant species. distributed throughout the Mediterranean and eastern Atlantic, and is very common in the coastal zone on sandy and muddy bottoms. 2. Material and methods 2. Material and methods In the Mediterranean large individuals, with males preceding females, leave deeper waters early in spring to migrate to 2.1 Sampling shallower water, where they reproduce. Sampling was carried out from February to September 2008 in 5 stations along the coast of Abruzzi (Martinsicuro, , This group is followed by a succession of smaller animals Montesilvano, Francavilla, Ortona) by local small-scale fishermen using two different gear types: bottom traps and trammel net. throughout the summer. In the autumn, a gradual descent to deeper water begins. Spawning usually peaks at water Two kinds of bottom trap were used, in line with local temperatures between 13° and 15ºC. The life cycle covers 12 fishermen’s habits. In the first four stations, typical to 24 months, depending on environmental conditions. parallelepiped-shaped cages with a metal frame and a net covering one entrance were used. In the Ortona station, fyke The growth rate is rapid: young hatched in early summer from nets consisting of cone-shaped bags mounted on rigid the spring brood usually spawn in the autumn of the following structures and completely covered by netting were used. year, while those from the autumn brood spawn in the spring of their second year of life. The trammel net was 500 m long and 2 m high, and consisted of three panels made of polyamide monofilament In Abruzzi waters (Adriatic Sea), cuttlefish are an with stretched mesh size of 40 mm. It was lowered at dusk important resource exploited by small-scale and hauled in after two days. ABRUZZI fisheries from March, during the reproductive period. A study on the efficiency of sampling At each station, 40 bottom traps and 1 gears (bottom traps and trammel nets) in trammel net were used, equivalent to catching cuttlefish was carried out as part of the working time spent in fishery research into the relationships between operations. 11 samplings were carried cuttlefish migration and sea water temperature, carried out in 2008 along the Abruzzi coasts. Figure 2. The sampling stations along the Abruzzi coast out at each station. Cuttlefish were counted, weighed and Cuttlefish size by month was also analysed. Figura 1. Cuttlefish the mantle length measured. 30 specimens from those caught by bottom traps were dissected and sexed for each sampling date and station, in order to detect differences in the arrival time of 2.2 Statistical analysis each sex. To verify the statistical difference between bottom trap and trammel net efficiency, both the number of Other organisms caught by the bottom specimens caught and their biomass were compared using the non-parametric Mann-Whitney test. traps were classified by species and counted to evaluate the sampling The association between sampling date and specimen length was investigated separately for males and females efficiency of this gear for other species. using linear regression analysis. Figure 3. Bottom traps

Figure 4. Trammel net 3. Results Overall, 992 cuttlefish were caught, with a total weight of 230.23 kg. Of these, 720 (143.03 kg) were collected by bottom trap 3.1 Comparison of bottom traps and trammel net and 272 (87.20 kg) by trammel net. The Mann-Whitney test identified a statistically significant difference between bottom trap and trammel net efficiency for both the number of specimens (U=2048, p<0.01) and the biomass (U=1979.5, p<0.01). The number of specimens caught and their biomass Total cuttlefish biomass caught by 40 bottom traps Number of cuttlefish caught by 40 bottom traps were significantly higher in the bottom traps (Figures 7-8). and 1 trammel net in 11 samplings and 1 trammel net in 11 samplings

50 160 45 43.299 Biomass of cuttlefish caught with bottom traps and Number of cuttlefish caught with bottom traps and 39.219 140 trammel net trammel net 40 37.041 120 35 100 Bottom traps 25000 60 30 80 25.243 25.13 Trammel net 50 kg B. traps 20000 25 60 T. net 40 40 20 17.033 cuttlefish of N°

16.399 cuttlefish of No. 20 15000 15 13.552 30 0 9.151 10000 10 20 4.163 (g) Biomass 5 Ortona 5000 10 Giulianova 0 Number of cuttlefish Francavilla Francavilla

Martinsicuro 0 0 ORTONA FRANCAVILLA MONTESILVANO GIULIANOVA MARTINSICURO Montesilvano Sampling station StationSampling of samling station 15/02/2008 29/02/2008 14/03/2008 28/03/2008 11/04/2008 25/04/2008 09/05/2008 23/05/2008 06/06/2008 20/06/2008 04/07/2008 18/07/2008 01/08/2008 15/08/2008 29/08/2008 12/09/2008 26/09/2008 15/02/2008 29/02/2008 14/03/2008 28/03/2008 11/04/2008 25/04/2008 09/05/2008 23/05/2008 06/06/2008 20/06/2008 04/07/2008 18/07/2008 01/08/2008 15/08/2008 29/08/2008 12/09/2008 26/09/2008 Figure 5. Total cuttlefish biomass per sampling point Figure 6. Number of cuttlefish per sampling point Sampling date Sampling date

BOTTOM TRAPS TRAMMEL NET BOTTOM TRAPS TRAMMEL NET

3.2 Association between sampling date and specimen length Figure 7. Biomass of cuttlefish caught with bottom traps and trammel net Figure 8. Number of cuttlefish caught with bottom traps and trammel net The linear regression identified a significant negative correlation between sampling date and specimen length for both males and females (Figures 9-10, Table 1) with a significantly negative angular coefficient (more evidently negative in the males). This result shows that the length of the caught specimens decreased from March to September, in line with literature reports. 3.3 Evaluation of additional species caught with

Table 1. Regression analysis Mantle lenght by month (females) Mantle lenght by months (males) the bottom traps

20 The additional species caught using bottom traps are shown in the bar chart 25 95% Confidence 18 of Figure 11.

Standard Interval for B 16 During the entire study period, in addition to the high number of cuttlefish GROUP Parameters B t Sig. 20 error 14 the bottom traps also captured 472 specimens of the common octopus Upper h Lower bound 12 bound 15 (Octopus vulgaris), which, as confirmed by local fishermen, is not usually

10 Constant 16.248 0.637 25.523 <0.0001 14.992 17.505 captured by trammel net or by other fishing methods in the study area. FEMALE 8 10 Bottom traps thus proved to be a valid method for sampling both Mantle lengt

Time (months) -0.504 0.114 -4.436 <0.0001 -0.729 -0.28 Mantle length 6 cephalopod species. However, limited numbers of other species were Constant 18.805 0.558 33.712 <0.0001 17.705 19.905 4 5 MALE caught by the bottom traps, confirming their high selectivity. Time (months) -1.142 0.11 -10.371 <0.0001 -1.359 -0.925 2 0 0 34567893456789 Month Additional species caught with the bottom trap Month Figure 9. Regression between mantle length and sampling Figure 10. Regression between mantle length and sampling 800 date (females) date (males) 700

600 4. Discussion Literature 1) Anderson, M. J., Gorley, R. N. & Clarke, K. R.. PERMANOVA+ for PRIMER: Guide to Software and Statistical Methods. PRIMER-E: Plymouth, UK 500 (2008). This study, carried out along the Adriatic coast of the Abruzzi, showed that: 2) Challier, L., Dunn, M. R., and Robin, J-P.. Trends in age-at-recruitment and juvenile growth of cuttlefish, Sepia officinalis, from the English Channel. e 400 ICES Journal of Marine Science, 2005, 62: 1671-1682. 3) Challier, L., Royer, G., Robin, J.P. Variability in age-at-recruitment and early growth in English Channel Sepia offıcinalis described with statolith 300 - bottom traps are considerably more efficient than the trammel net for the analysis Aquat. Living Resour. 15 (2002) 303–311 capture of cuttlefish; 4) Denis, V., Robin J.P. Present status of the French Atlantic fishery for cuttlefish (Sepia officinalis) Fisheries Research 52 (2001)11±22 specimens of No. 5) Dunn, M.R. Aspects of the stock dynamics and exploitation of cuttlefish, Sepia officinalis (Linnaeus, 758), in the English Channel Fisheries 200 Research 40 (1999) 277±293 - the first specimens of cuttlefish of both sexes to arrive inshore are the 6) Fabi, G., Grati, F , Lucchetti, A., Scarcella, G. Osservazioni preliminari sulle catture di Sepia officinalis con tre attrezzi da posta in medio Adriatico. 100 largest, with size decreasing over time; Biol. Mar. Medit.(2001) 8 (1) : 660-664. 7) Jereb, P. Roper C.F.E.. Cephalopods of the World. An Annotated and Illustrated Catalogue of Cephalopod Species Known to Date. Volume 1. 0 Chambered Nautiluses and Sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae and Spirulidae). FAO Species Catalogue for s r a lii us rus e fa r a cis a sis x us inali aris y laris arus br eri n Fishery Purposes, No. 4, Vol. 1. (2005) lg cul scro rbatus nge m rros hy abrilla - the use of bottom traps also enables the capture of other valuable fic orm s nig muletus a co um ci um aurat line ovat s vu run iu annu a r is p ro 8) Kleinbaum D., Kupper L., Nizam A., Muller K. . Applied regression analysis and other Multivariate Methods. London Duxbury press (1998) a of x t m ob s il cephalus ger gam ena rina la d yc arus us c otus pi pu G aen ia b rio p n ure thus rp lus su on Ph S s ca in species. Se cto lodu Mug Mullus b Maja squinado C arus Sc Um Se te erra Dentex dentex 9) Siegel, S., Castellani, N.J. Nonparametric Statistics for the Behavioural Sciences. New York: McGraw. Hill (1988). O M na ip m S Oblada melanura rach D Sco Mul alis icentrarchusT labra hog Ho B UranoscopusD scaber Lit Hippocampus hippocampus Species

Figure 11. Number of species caught using bottom traps