BiologÃa del langostino Penaeus kerathurus. (Forsköl, 1975) del golfo de Cádiz. II: Distribución y estructura de la población. Investigación Pesquera. 50(2): ...
Thalassas, 2006, 22 (1): 39-44 An International Journal of Marine Sciences
EXPLOITATION PATTERN OF THE ARTISANAL FLEET IN THE AREA OF THE GUADALQUIVIR RIVER MOUTH (GULF OF CÁDIZ, SW SPAIN)
LUIS SILVA1, IGNACIO SOBRINO1, EVA GARCÍA2 & ALBERTO GARCÍA2
Keywords: Gulf of Cádiz, Guadalquivir River, artisanal fleet, cluster analysis, fishing trip types.
ABSTRACT
INTRODUCTION
The zone adjacent to the mouth of the Guadalquivir River (Gulf of Cádiz) is of great fishing importance and is frequented by the artisanal fleets of the nearby localities, particularly by the Chipiona fleet. A k-means cluster analysis with known centres was applied for the description of the exploitation pattern, taking as base data the matrix of daily landings of the period 1999-2000 in the Port of Chipiona, in order to classify them in "fishing trips types", on the basis of their species composition. 73% of the annual activity of the artisanal fleet is developed in the protected area denominated "Hatchery Zone". The greater activity corresponds to two fishing trip types, the LANG fishing trip targeting the prawn during the spring, and the ACE fishing trip, which targets the wedge sole during the winter. Both fishing trips comprise 53% of the total. The seasonality of the fisheries in the study area is closely related to the variations in the abundance of the main commercial species throughout the year, determined as well by environmental factors and by the biology of these species.
The estuary areas are very productive and rich fishing zones, which are frequented by species that use them to feed or to reproduce (Anon, 1999). In the case of the Guadalquivir River mouth, this fishery significance is manifested by the numerous species caught by the artisanal fleet of the adjacent localities, as is the case with Chipiona. In addition, the fishery importance of this zone of the Gulf of Cádiz has been guaranteed since a Ministerial regulation of 1966 (13th June), which was pioneering in Spain. This regulation protects a wide area under the figure of a "Hatchery Zone for caramote prawns and wedge soles"(Figure 1).
Instituto Español de Oceanografía. (1)Estación Oceanográfica de Cádiz, (2) C.O. Málaga. Estación Oceanográfica de Cádiz, Apdo.2609, 11006 Cádiz.
This work comprises the results of the "Previous Study for the Boundary of a Fishery Reserve in the Guadalquivir River mouth" carried out by personnel of the Instituto Español de Oceanografía (IEO) of Cádiz and Málaga, under a specific agreement between the IEO and the Main Directorate of Fishery of the Junta de Andalucía. In the present work, the exploitation pattern of the artisanal fleet of the locality of Chipiona is described, as well as the main fleet operating in the zone adjacent to the mouth of the Guadalquivir River. Multivariate analyses were applied to the daily landings in order to characterize "fishing trip types". In addition, interviews with personnel from this sector, as
39
Luis Silva, Ignacio Sobrino, Eva García & Alberto García
MATERIALS AND METHODS For this study, daily landings of the artisanal fleet registered in the Port of Chipiona (Cádiz) during the period 1999-2000 have been used, by boat and by fishing trip separately. In order to classify these landings in "fishing trip types", a matrix with the landings of both years was made. The matrix contains as many rows as landings or daily fishing trips and as many columns as landed species in each fishing trip, including the corresponding ones to the date and the boat code. A k-means cluster analysis with well-known centres was applied (Visauta, 1998), using the matrix of centroids obtained after the application of the same methodology to the matrix of landings of the artisanal fleet of the main ports of the Gulf of Cádiz (Silva et al., 2002). This method was successfully applied by Jiménez (2002) in the landings of the trawler fleet in the Gulf of Cádiz. The information was completed with interviews and surveys with personnel from this sector, as well as by observations on board commercial vessels of the study area which carry out fishing trips targeting the main species. RESULTS AND DISCUSSION
Figure 1. Study Area. Hatchery Zone, dotted.
well as observations on board the main commercial fishing trips, were carried out to simplify the descriptions of the fleet activity and its exploitation pattern in the study area.
Chipiona 1999
Chipiona 2000
Wedge sole 23%
Others 44%
Blue fish 6%
Common cuttlefish 7%
The landings of the artisanal fleet in the Port of Chipiona during the period 1999-2000 were around 560 t (303 t in 1999 and 257 t in 2000). The wedge sole (Dicologoglossa cuneata) and the caramote prawn (Melicertus kerathurus) were the main landed species (Figure 2). The number of fishing trips or daily
Caramote p rawn 15%
M eagre 5%
Wedge sole 14%
Others 54%
Blue fish 10%
Common cuttlefish 6%
Caramote prawn 11%
M eagre 5%
Figure 2. Relative importance of the species composition of the landed catches by the artisanal fleet of Chipiona during the period 1999-2000.
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Exploitation Pattern Of The Artisanal Fleet In The Area Of The Guadalquivir River Mouth (Gulf Of Cádiz, Sw Spain)
Table I. Relative importance of the species composition of the main fishing trip types. Artisanal fleet of Chipiona, period 1999-2000, expressed as % of the catch.
Fishing trips types LANG ACE CH CORV SARG BRE LUB MER HER LENG
Nº fishing trips types
1st species (%)
2nd species (%)
3rd species.(%)
6636 2934 1065 1037 732 608 586 505 411 286
Prawn 75.2 Wedge sole 91.1 Common cuttlefish 77.4 Meagre 84.3 White seabream 64.7 Common pandora 42.6 European seabass 92.1 Hake 45.5 Stripped seabream 53.4 Common sole. 72.3
Wedge sole 15.1 Caramote prawn 4.7 Caramote prawn 3.7 European seabass 4.2 Meagre 12.2 Bluefish 19.7 Flathead grey mullet 2.2 Atlantic horse mackerel 21.8 Caramote prawn 9.6 Common cuttlefish 10.4
Common cuttlefish 6.3 Hake 1.4 Wedge sole 6.6 Bluefish 3.0 European seabass 10.1 Atlantic horse mackerel 10.2 Meagre 1.7 European seabass 6.1 Common cuttlefish 5.3 Wedge sole 4.7
landings was 17755 (9351 fishing trips in 1999 and 8404 fishing trips in 2000). A total of 38 fishing trips types were identified, each one being characterized by the species composition of the catches. Eleven species represented around 85% of the total (Tables I and III). LANG and ACE fishing trip types were the most relevant, with the caramote prawn and the wedge sole as target species respectively and both comprising more than 50% of the fishing trips. They were followed by the CH (6%), the CORV (5.8%) and the SARG (4.1%) fishing trips, which represent 70% of the total, with the common cuttlefish (Sepia officinalis), the meagre (Argyrosomus regius) and the white seabream (Diplodus sargus) as their target species, respectively (Tables I and III). The clear directionality of the fisheries towards the different target species in the main fishing trip types is manifested by the high percentage of these species in relation to the bycatch species within the total of each fishing trip (Table I). This targeting is reinforced in certain fishing trip types by the type of fishing gear used and the fishing operation, both closely related to the target species. According to the information from the survey observations on board made in the area, the main fishing trip types developed in the Hatchery Zone (dotted zone in Figure 1) are LANG, ACE, CH, CORV, SARG and LUB fishing trips. The monthly evolution of the number of fishing trips shows a noticeable seasonality. The vessels alternate and/or combine different fishing gears throughout the year, depending
on the target species. Thus, during the autumn and winter the ACE fishing trip predominates, targeting the wedge sole. During the spring and the first half of the summer, this changes to the LANG fishing trip (Figure 3), which targets the caramote prawn. CH fishing trips, targeting common cuttlefish, are maximal at the end of winter, whereas the fishing trip targeting the European seabass (Dicentrarchus labrax) (LUB), is developed mainly during the winter months. The greater number of fishing trips targeting the meagre (Argyrosomus regius) is registered during the spring and to a lesser extent during the summer (Figure 3). This noticeable seasonality of the different fishing trips is closely related to the biology of the target species. In the case of the caramote prawn, a sexual concentration of reproductive individuals in the Hatchery Zone takes place in front of Torre Zalabar (Figure 1) in the springtime, prior to the spawning period (Rodríguez, 1985, 1986). This reproductive period coincides with the period of greater activity of the LANG fishing trips, targeting this species. An increase in fishing activity is observed during the autumn and to a lesser extent during the spring, attributed to the recruitment to the area of juveniles coming from the tidal channels of the low Guadalquivir River (Rodríguez, 1986; Silva et al., 2003). According to Rodríguez (1986), the larvae born in the springtime are carried by the currents from the spawning areas to the nursery zones, located in the low part of the Guadalquivir estuary, where they reside during the summer until they reach what Rodríguez calls "critical migration size".
41
Luis Silva, Ignacio Sobrino, Eva García & Alberto García
Table II. Monthly relative importance (expressed in %) of the mainly fishing trip types obtained from the Chipiona artisanal fleet landings, during the period 1999-2000. (* subtotal, in %, of the fishing trips carried out in the Hatchery Zone).
1 1,7 38,7 7,4 3,1 4,7 14,0 69,6 3,1 10,1 1 1,8 85,6 14,4 100
LANG ACE CH CORV SARG LUB * Subtotal BRE MER HER LENG Total Rest TOTAL
2 0,8 30,6 19,3 1,3 4,4 10,0 66,4 2,4 5,8 0,6 2,4 77,6 22,4 100
3 9,9 26,3 19,3 7,3 3,0 4,3 70,2 2,3 4,2 1,2 2,8 80,7 19,3 100
Months (period 1999-2000) 4 5 6 7 48,7 63,7 73,1 56,1 14,0 4,5 2,3 2,4 6,7 7,1 4,0 2,7 13,9 8,5 3,1 4,0 2,8 2,3 2,2 5,1 0,8 0,7 0,1 0,8 87 86,8 84,8 71,2 0,1 0,1 1,2 6,4 0,2 0,1 0,3 1,5 0,5 1,1 1,1 3,4 1,8 1,1 0,3 0,4 89,6 89,2 87,7 82,9 10,4 10,8 12,3 17,1 100 100 100 100
8 29,9 5,7 4,1 7,9 6,7 0,8 55,1 9,1 1,4 7,8 0,6 74 26 100
9 17,2 19,6 2,2 7,1 6,1 1,4 53,7 6,7 1,7 5,2 0,8 68,1 31,9 100
10 45,7 19,1 1,1 3,2 5,3 2,4 76,7 2,4 2,7 4,1 0,2 86,1 13,9 100
11 37,4 23,4 0,9 5,2 4,0 2,2 73,1 4,7 3,5 0,9 4,3 86,5 13,5 100
12 7,5 39,1 1,1 5,9 4,4 7,5 65,5 4,6 7 0,8 5 82,9 17,1 100
Table III. Resume of the explotation patterns of the Chipiona artisanal fleet in the study area (* = in the Hatchery Zone; 1 = mesh size between 20 and 25mm, 2 = mesh size between 40 and 45mm ).
LANG (*)
Relative importance Target species (%) Caramote prawn 37,4
ACE (*)
16,5
Wedge sole
June-August
December-February
Trammelnet1
CH (*)
6,0
Common cuttlefish
February-March
September-November
Trammelnet2
CORV (*)
5,8
Meagre
April-May, august
January-February
Gillnet
SARG (*)
4,1
White seabream
July-October
March
Gillnet
BRE
3,4
Common pandora
July-August
April-May
Gillnet
LUB (*)
3,3
Europen seabass
January
April-September
Gillnet
MER
2,8
Hake
December-February
April-June
Gillnet
HER
2,3
Stripped seabream
July-September
December-April
Gillnet
LENG
1,6
Common sole
July-October
Gillnet
CHV
1,2
Bluefish
February-March, November July-September
March-May
Gillnet
Fishing trips types
42
Maximum activity
Minimun activity
Fishing gears
May-June, October
January-February
Trammelnet1
Exploitation Pattern Of The Artisanal Fleet In The Area Of The Guadalquivir River Mouth (Gulf Of Cádiz, Sw Spain)
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Figure 3. Temporal evolution of the fishing trip types developed in the Hatchery Zone, expressed in percentage of the total. Period 1999-2000.
The greater fishing activity of the ACE fishing trips occurs from the middle of the autumn to the beginning of the spring, corresponding to the reproduction period of the wedge sole in the study area (Jiménez et al., 1998). García-Isarch et al. (2003) detected the greater abundances of adults and reproducers during the winter months in the deepest area of the Hatchery Zone. Additionally, the months of greater fishing activity targeting the common cuttlefish, the CH fishing trips, are detected at the end of the winter, coinciding with the spawning period of the species in the zone (Ramos et al., 2000). Regarding the fisheries of the meagre and the European seabass in the study area, the information about the biology of these species in the Gulf of Cádiz is sparse. Biological samplings made "in situ" (unpublished data) and interviews with local fishermen indicate that, like in the previously mentioned cases, the greater fishing activity of the CORV (meagre) and the LUB (European seabass) fishing trips is developed
during the period when both species approach the shallow waters near the mouth of the river for their spawning (meagre in spring and European seabass in winter). The results of the analysis of the monthly relative importance of each fishing trip type indicate that approximately 73% of the annual activity of the artisanal fleet is developed in the Hatchery Zone. Maximum values of around 86% occur during the spring (May-June), attributed almost totally to the fishing trips targeting the caramote prawn (Table II). During the winter, the fishery of the wedge sole predominates in the area, mainly in the Hatchery Zone, although it is shared to a lesser extent with the fishing trips targeting species like the common cuttlefish and the European seabass. Outside the Hatchery Zone, the winter activity is focussed on the fishing trips targeting the European hake (Merluccius merluccius), (MER fishing trips) in 43
Luis Silva, Ignacio Sobrino, Eva García & Alberto García
deep waters (> 20m) to the south of the study area. During the summer and part of the autumn, fishing activity is mainly concentrated between the HER and the BRE fishing trips. The former targets the stripped seabream (Lithognathus mormyrus) in the zone between Torre la Higuera and Torre Zalabar (Figure 1), and the latter targets the common pandora (Pagellus erythrinus) in a wide area between Torre la Higuera and the southern Chipiona, between 15 and 30-40 m deep. The activity outside the Hatchery Zone during the spring is considerably reduced, as the main fishing activity targets the meagre and the caramote prawn inside the protected area.
4): 493-503. JIMÉNEZ, M.P., SOBRINO, I. & F. RAMOS, 1998. Distribution pattern, reproductive biology and fishery of the wedge sole Dicologoglossa cuneata in the Gulf of Cádiz, south-west Spain. Marine Biology 131:173-187. JIMÉNEZ, M.P., 2002. Aplicación de análisis multivariantes para la obtención y estandarización de esfuerzos pesqueros en pesquerías multiespecíficas. Las pesquerías demersales del Golfo de Cádiz. Tesis doctoral, Universidad de Cádiz, 327 pp. RAMOS, F., SOBRINO, I. & L. SILVA, 2000. The life history of Sepia officinalis (Cephalopoda: Sepiidae) in the Gulf of Cádiz (SW Spain). In Proceedings of the Millenium Cephalopod Conference:
Therefore, the artisanal fleet of Chipiona uses alternatively and/or simultaneously different fishing gears throughout the year in the different fishing trip types, in relation to the target species. This is typical of the artisanal fisheries in many other areas (Camiñas, 1990). The oscillations in the abundance of the main fishing species in the zone of the Guadalquivir River mouth determine the seasonality of the different fleets. These abundance changes are mainly controlled by environmental factors of trophic and reproductive nature, among others. In addition, the identification of fishing trip types in the artisanal fleet on the basis of the specific composition of the catches by means of multivariable analysis has been proven to be a very useful tool for getting knowledge and determining the exploitation pattern of the fleets under study. This methodology greatly simplifies the volume of information that is generated by a fishery of this nature and is very useful in its application to other areas with similar fisheries.
CIAC 2000. Cephalopod Biomass and Production, University of Aberdeen, Scotland, 3-7 July 2000, (ed. University of Aberdeen), 99 pp. RODRÍGUEZ, A., 1985. Biología del langostino Penaeus kerathurus (Forsköl, 1975) del golfo de Cádiz. I: Reproducción. Investigación Pesquera. 49(4): 581-595. RODRÍGUEZ, A., 1986. Biología del langostino Penaeus kerathurus (Forsköl, 1975) del golfo de Cádiz. II: Distribución y estructura de la población. Investigación Pesquera. 50(2): 187-202. SILVA, L., GIL, J. & I. SOBRINO, 2002. Definition of fleet components in the Spanish artisanal fishery of the Gulf of Cádiz (SW. Spain, ICES division Ixa). ). Fish. Res., 59: 117-128. SILVA, L., GARCÍA-ISARCH, E., SOBRINO, I. & A. GARCIA, 2003. Distribución espacio-temporal del langostino Melicertus kerathurus (Forskol, 1775) en aguas de la desembocadura del río Guadalquivir (Golfo de Cádiz). Bol. Inst. Esp. Oceanogr., 19 (14): 41-47. VISAUTA, 1998. Análisis estadístico con SPSS para Windows. Vol. II, Estadística multivariante. Mc. Graw-Hill, Interamericana de España, S.A., U. Madrid.
REFERENCES ANONYMOUS, 1999. Ordenación y regulación de la actividad pesquera en el estuario del Guadalquivir. Dirección General de Gestión del Medio Natural, Consejería de Medio Ambiente, Junta de Andalucía. 163 pp. CAMIÑAS, J.A., 1990. Pesquerías artesanales mediterráneas. El caso andaluz. Revista de Estudios Agrosociales, MAPA nº155: 83-117. GARCÍA-ISARCH, E., SILVA, L., GARCÍA, A. & I. SOBRINO, 2003. Distribución espacio-temporal de la acedía Dicologoglosa cuneata (Moreau, 1881) en aguas de la desembocadura del río Guadalquivir (Golfo de Cádiz). Bol. Inst. Esp. Oceanogr., 19 (1-
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