Working document presented to the ICES the Workshop on the necessity for crangon
(Brown shrimp) and cephalopod management (WKCCM)
Copenhagen,, 8 – 9 October 2013.
MANAGEMENT OF OCTOPUS (Octopus vulgaris) IN THE SPANISH WATERS
OF THE GULF OF CADIZ. ICES SUBDIVISION IXa-south.
Luis Silva and Ignacio Sobrino
Instituto Español de Oceanografía
Centro oceanográfico de Cádiz
Puerto pesquero, Muelle de Levante S/N. Apdo. 2609
11006 - Cádiz (Spain)
The common octopus Octopus vulgaris , Cuvier, 1797, is an abundance species in the
Spanish waters of the Gulf of Cádiz (ICES Subdivision IXa-South), inhabiting from intertidal zone to about 150 m deep (Figure1). This species is caught by the demersal fishery, witch is constituted by bottom-trawl fleet and artisanal fleet fisheries pooled and it is characterised by the multispecies nature of its landings. In this fishery, the common octopus stands out as the most important species in terms of the volume of landed catches. For the historical series of annual landings analysed to date (1994-2012 period), octopus landings accounted, on average, for 15 % in weight (1500 t) of the total catches landed by the demersal fleets. Octopus annual landings ranged between 3242 tonnes in 2012 and 285 tonnes in 2011 (Figure 2). Possibly, such oscillations may be related with environmental changes, mainly the rain and the discharge of the rivers.
Generally, after of heavy rain, the abundance of octopus decrease a lot (Sobrino et al .,
2002)
The octopus fishery in the study area is of a marked multifleet-multigear nature, in which participate both the trawl and artisanal fleets. Octopus usually is a by-catch specie for the trawl fleet, although specific fishing trips for octopus and octopuscuttlefish are also undertaken by this fleet (Sobrino et al ., 1994; 1995). Artisanal fleets targeting octopus use different species-specific fishing gears and traps (Silva et al.,
2002; Silva and Sobrino, 2003).However, a clear geographical differentiation in the use of these gears can be observed (Figure 1). The Easternmost fleets (Province of Cádiz) use home-made hand jigs (´ chivos ` and ´ pulperas `) (Figures 7 to 15), while the wersternmost artisanal fleets (Province of Huelva) mainly use clay-pots, locally termed
´ alcatruces
` or ´ cajirones ` (Figures 4 and 6. Also noteworthy is the non-directed octopus fishing with artisanal traps (Figures 3 and 5), hook-lines and trammel nets. In recent 10 years, smaller traps targeting octopus area used in both areas, while is disappearing the use of non-directed trap.
Although the species is practically exploited over all the continental shelf, two main fishing grounds can be differentiated (Figure 1). One area is located off the Huelva coasts, between Ayamonte and Mazagón, in gravel-sand-mud bottoms ranging from 10 m to 70/80 m depth, and the other in the Cádiz coasts, between Cabo Roche and Cabo
Trafalgar, from the coast line up to 80 m depth, where the rocky bottoms inserted with sand bottoms are dominant. In this eastern area, strong currents are frequent because of its proximity to the Strait of Gibraltar. The Artisanal fleets exploit the whole extent of

these areas, whereas the depth range exploited by the trawl fleet in these fishing grounds is restricted to those depths beyond the 6 nautical miles offshore line, which corresponds to the shallowest legal limit for trawl fishing (Figure 16)(Ramos et al .,
1996).
During the last 19 years octopus catches landed by the trawl fleet accounted, on average, for 62% of the total annual landings of the species. However, the relative importance of the octopus landings in the artisanal fishery, with 38% on average, has increased up to reach 71% in 2012 (Figure 2). Within the artisanal fishery, the hand-jig fleet contributed to the highest volume of landings, which represented about 58 % in weight followed by the clay-pot fleet with 35%. The remaining 7% was landed by the artisanal fleets fishing with traps, hook lines, and, to a lesser extent, trammel nets.
Futhermore, the monthly evolution of landings during the most recent years show that the octopus artisanal fishery has marked seasonality, the highest landings being recorded from late winter to middle of spring. This seasonality is also similar to monthly landings in bottom trawl fleet, although less marked. (Figure 17) Directionality seems to be the main cause of the more fluctuating values observed in the monthly landings of this fishery as compared to those of the trawl fleet.
In 1996, a biological and fishery study was carried out in order to get information to management the fishery of this species. A sampling of the octopus catches landed by the different fleets exploiting this resource was undertaken on a monthly basis. Annual size frequency distributions per fishing gear were obtained and compared. The results of the test showed the existence of significant differences between the population fraction jointly exploited by the trawl and clay-pot fleets, with smaller individual in catch of trawler, and that exploited by the hand-jig, hook-line and trap fleets (Silva et al., 1998).
The biological study reported information about the reproduction period, first size/weight at maturity and fecundity. Fishery and biological information was used to establish the main first measure in order to manage the fishery for all types of gears: minimum legal weight of 1 kg. (Orden, 22 november 1996, BOE 290). Besides, it was banned to fish octopus by recreational vessel.
Besides of the multifleet-multigear nature of this fishery, the different regulation due to the different Administration is a problem in order to manage it. The Regional
Administration has competence in shallow waters delimited by base lines and the
Central Administration in the rest of the waters.
The bottom trawl is only regulated by Central Administration, witch established in 1993 a Real Decreto 632/1993 including the main aspect to regulate this fishery: vessel characteristics, fishing area outside six miles of coastline and fishing effort per week, among others. Years later, different Fishing Plans for the Gulf of Cadiz have been established since 2004 in order to reduce the fishing effort of the bottom trawl fleet
(ORDENES APA/3423/2004, APA/2858/2005, APA/2883/2006, APA/2801/2007,
ARM/2515/2009, ARM/58/2010, ARM/2457/2010). The main aspect of these fishing plans was the closed fishing season implemented in autumn, with a gradual increase in the number of days (45, 60, and 90 days per year). Currently, the closed season is of 45 days, and an important aspect is that it is establishes when appear the recruitment in the fishing ground. This measure reduced a lot the illegal landing of immature specimens.
Additionally, an increase of mesh size from 40 to 55 mm or more was implemented at the end of 2009 in order to reduce discards of individuals below the minimum landing

size. This measure affects all species caught by this gear, including the octopus 17. It can be observed in figure 17 the increase of landings after the closed season.
In relation with the artisanal fisheries, including octopus fishery, the RD 1428/1997 published by Central administration in 1997 set up the rules related with the number of trap or clay-pots per vessel, among others aspects. However, in order to maintain a sustainable fishery for octopus, it was established in both Administration a specific fishing plan for the conservation and sustainable management of this fishery in the fishing ground of the Gulf of Cádiz: ORDEN 2438/2005, 20th July, by Central
Administration, and RESOLUCION on 19 th September 2005 (BOJA 189) by Regional
Administration. The main management measure included in these regulations was the closed season set up in spring from 1 June to 15 July, only targeted to artisanal fisheries, and in autumn from 15 September to 31 October, targeted to all demersal fleet. The spring closed season is intended to protect the spawner during the main peak of the reproduction period. The octopus laid the eggs in shallow waters in spring-summer, and for this reason only affect to artesanal fleet. On the other hand, the autumn closed season is established in order to protect the recruitment that appears in this period. Other management measure included in these regulations was to constrain the use of clay-pots and trap, only to the westernmost area of the Gulf of Cádiz.
An important aspect to take into account for the management of this species is her trophic level. Recent research highlight that the Rose shrimp ( Parapenaeus longirostris ), cephalopods and dolphins present important overall effects as keystone species on the rest of the groups. Specially, Octopus vulgaris is located in a high trophic level in the food-web of the Gulf of Cadiz (Figure 18)(Torres et al ., 2013).
Finally, it is necessary to take into account the unreported data from the illegal landing carried out by recreational fishery in order to manage this fishery, as well the illegal high number of trap and clay pots used by some artisanal vessel.
REFERENCES.
SOBRINO, I., M.P. JIMÉNEZ, F. RAMOS & J. BARO, 1994.- Descripción de las pesquerías demersales de la Región Suratlántica Española. Inf. Téc. Inst. Esp.
Oceanogr ., 151: 79 pp.
SOBRINO, I., F. RAMOS, M.P. JIMÉNEZ & J. BARO, 1995.- Study on the Spanish trawling fleet components and mapping of resources exploited by this fleet off the Gulf of Cádiz. Final Report, Cooperative Project IEO/EC-DGXIV/C/1/STUDY/94/029, 134 pp.
RAMOS, F., I. SOBRINO, & M.P. JIMÉNEZ, 1996.- Cartografía temática de caladeros de la flota de arrastre en el Golfo de Cádiz. Junta de Andalucía: Informaciones
Técnicas
, 45-96: 44 pp, 12 mapas.

Silva, L., Sobrino, I., and Ramos, F. 2002. Reproductive Biology of the common octopus ( Octopus vulgaris , Cuvier 1797, Cephalopoda, Octopodidae) in the Gulf of
Cádiz (SW Spain). Bulletin of Marine Science, 71: 837-850.
Sobrino, I., Silva, L., Bellido, J.M., Ramos, F., 2002. Rainfall, river discharges and sea tempera-ture as factors affecting abundance of two coastal benthic cephalopod species in the Gulf of Cadiz (SW Spain). Bull. Mar. Sci ., 71 (2), 851–865
Torres , M.A., Coll, M., Heymans, JJ., Christensen, V. and Sobrino, I., 2013.
Food-web structure of and fishing impacts on the Gulf of Cadiz ecosystem (South-western
Spain).Ecological Modelling 265: 26-44.
SILVA, L., SOBRINO, I., RAMOS, F., 1.998. Fishing exploitation pattern of the common octopus, Octopus vulgaris Cuvier, 1797, in the spanish waters of the Gulf of Cádiz.
ICES Division IXa. En: Report of the Working Group on Cephalopod Fisheries and Life
History , ICES CM 1.998/G:7, Ref. ACFM, 39-45.

37.00°
PORTUGAL
Guadiana river
Isla Cristina
30m
100m
200m
500m
HUELVA
Guadalquivir river
Sanlúcar
CÁDIZ
Conil
Barbate
TRAWL
CLAY POTS
HAND JIPS
TRAPS
1000m
Tarifa
36.00°
MOROCCO
7.00° 6.00°
Figure 1. Map showing the study area and the main fishing grounds by gear type in the Spanish waters of the Gulf of Cádiz.
Landings Octopus vulgaris Subdivision IXa-south
2500 3500
2000
1500
3000
2500
2000
1000
500
1500
1000
500
0 0
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
Years
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
Trawler fleet Artisanal fleet Demersal fleet

Figure 2. Landings of Octopus vulgaris by fleets in ICES Subdivision IXa-south (Gulf of
Cadiz).
Figure 3.- Gulf of Cádiz artisanal fisheries. Traps (" nasa ") for fish-cephalopods in the Barbate fishing port.

Figure 4.- Gulf of Cádiz artisanal fisheries. Clay-pots (" alcatruz ") in the Isla Cristina fishing port.

Bait bag
Nylon braided thread
Plastic mesh without knots
(44 mm mesh)
Rope to close the door
BAIT BAG
Door
Wooden poles sewed to the net
Nesh tied by simple knots
Wooden stick
Plastic net
Buoy
Rochy or sandy bottoms 30 traps as maximum
FRONTAL VIEW
Figure 5.- Gulf of Cádiz artisanal fisheries. Schematic diagram and methods of deployment of traps (" nasa ") for fish-cephalopod (common octopus). fathoms

Multifilament thread of braided nylon (10 mm)
Slipknot
Multifilament thread of braided nylon (6 mm) to the buoy
CLAY-POT SECTION
Figure 6.- Gulf of Cádiz artisanal fisheries. Schematic diagram and method of deployment of the clay-pots (" alcatruz ") for common octopus.

Galvanised wire (4 mm)
Nylon M.T. 2220
Knot
Hook nº3
Metalic tube (16 mm

)
Filling of leag
Central wire
FRONTAL VIEW
Figure 7.- Gulf of Cádiz artisanal fisheries. Schematic diagram of the " chivo " hand-jig for common octopus.

Figure 8.- Gulf of Cádiz artisanal fisheries. Detail of the fishing manoeuvring of common octopus with " chivo " hand-jig.
Figure 9.- Gulf of Cádiz artisanal fisheries. Detail of " chivo " hand-jigs baited with sardines and conger eel.

Figure 10.- Gulf of Cádiz artisanal fisheries. Detail of the capture of an octopus with a ”chivo” hand jig by the Conil artisanal fleet.
Figure 11.- Gulf of Cádiz artisanal fisheries. Detail of the " pulpera " hand-jig types used by the
Barbate artisanal fleet.

Figure 12.- Gulf of Cádiz artisanal fisheries. Detail of a " pulpera " hand-jig type baited with a bogue ( Boops boops ), used by the Barbate artisanal fleet.
Figure 13.- Gulf of Cádiz artisanal fisheries. Detail of the " pulpera " hand-jig types used by the
Barbate artisanal fleet.

Figure 14.- Gulf of Cádiz artisanal fisheries. Detail of the " pulpera " hand-jig types used by the
Barbate artisanal fleet.
Figure 15.- Gulf of Cádiz artisanal fisheries. Detail of the " pulpera " hand-jig types used by the
Barbate artisanal fleet.

Octopus vulgaris 1993-2003 period.
Monthly landings by fleet
180
160
140
120
100
80
60
40
20
0
1 2 3 4 5
Bottom trawl fleet
6 7
Months
8 9
Artesanal fleet
10 11 12
Octopus vulagris 2004-2012 period.
Monthly landings by fleet
180
160
140
120
100
80
60
40
20
0
1 2 3 4 5 6 7
Months
8 9 10 11 12
Bottom trawl fleet Artesanal fleet
Figure 17. Mean monthly landing in tonnes for the periods 1994-2003 and 2004-2012 years in the Gulf of
Cádiz.

M.A. Torres et al. / Ecological Modelling 265 (2013) 26– 44
Figure 18. Flow diagram of the Gulf of Cadiz food web. The size of each circle is proportional to the biomass of the functional group. All the functional groups are represented according to their trophic levels on the y-axis (TL) and connected to each other through light gray lines that represent prey–predator relationships. Groups are organized considering their pelagic, demersal and benthic habitats.