We analysed the fishing fleet dynamics in the Cíes Islands, located in a National Land-Marine Park of Galicia. By interviewing fishers we identified the fleet fishing in the study area and obtained temporal data on effort and catch. Then we performed multivariate analyses of the catch profiles to identify the fishing strategies and their temporal dynamics. Our results highlight the complexity of the fishery system, composed of 565 boats that used 19 fishing gears and 33 strategies in an area of 26.6 km2. Octopus and velvet crab pots, gillnets targeting hake, trammel nets targeting European spider crab or ballan wrasse, clam rakes, and hand harvesting of gooseneck barnacles and razor shells are the strategies most used. In addition, most of the boats are generalists and use up to seven different fishing strategies throughout the year. This flexibility of the fleet to change the target species generates a wide diversity of annual fishing patterns that increases the complexity of the fisheries and the difficulty of managing them. The implementation of data collection programmes that include fleet dynamics and spatial data are key factors for developing effective management regulations consistent with the complexity of the system.
Este estudio analiza la dinámica de la flota pesquera en las Islas Cíes, localizadas en el Parque Nacional marítimo-terrestre de Galicia. Por medio de entrevistas a pescadores hemos identificado la flota en la zona de estudio y hemos obtenido datos temporales de esfuerzo y capturas. A continuación hemos llevado a cabo un análisis multivariante de los perfiles de capturas para identificar las estrategias de pesca y su dinámica temporal. Nuestros resultados resaltan la complejidad del sistema pesquero, compuesto por 565 barcos que usan 19 artes y 33 estrategias de pesca diferentes en un área de 26.6 km2. Las estrategias de pesca más usadas son nasas de pulpo y nécora, arte de enmalle fijo dirigido a la captura de pescadilla, trasmallos dirigidos a la pesca de centolla y maragota, rastros para almeja, y recolección manual de percebe y navaja. Cabe decir también que la mayoría de los barcos son generalistas y utilizan hasta 7 estrategias diferentes a lo largo del año. Esta flexibilidad de la flota para cambiar su especie objetivo genera una amplia diversidad de patrones anuales de pesca que todavía incrementan más la complejidad del sistema y la dificultad para gestionarlo. La implementación de programas de recogida de datos que incluyan la dinámica de la flota y datos espaciales son clave para desarrollar unas regulaciones de gestión efectivas y consistentes con la complejidad del sistema.
The fraction of assessed stocks fished within biologically sustainable levels decreased by almost 20% from 1974 to 2011 (
One of the most innovative and novel approaches that is being currently applied is the ecosystem approach to fisheries (EAF) (
Understanding the fleet behaviour and fishing patterns in space and time is one of the essential requirements for implementing the EAF for two reasons. First, most small-scale fisheries are complex systems that encompass different fleets exploiting a huge variety of species. Depending on the context in which they work, boats can easily change their target species in order to maximize the economic benefits and use different fishing strategies or
Several studies also mention the need to understand the spatial and temporal heterogeneity of the marine ecosystems and their associated human communities, as well as the multiple scales on which they operate (
This article contributes to the EAF by providing information on fishing fleet dynamics, fishing strategies and fishing effort around the Cíes Islands, a small archipelago included in the National Land-Marine Park of the Atlantic Islands of Galicia. Despite the establishment of the National Marine Park in 2002, data currently available only focus on the economic performance of the fleet (
Galicia (NW Spain) is one of Europe’s regions with the highest socio-economic dependence on fishing, due to its high production and employment rate and its relationship with other local economic sectors (
Our study was carried out in the inner coastal waters of Galicia, where fishing resources are managed by the Galician government (although always following the rules established at broader scales, such as total allowable catches imposed by the European Union for many target species of purse seine). Boats have a fishing licence in which the authorized fishing gears are specified. Boats are allowed to use a maximum of five different fishing gears, although they can only use one per day, and purse seiners are only allowed to fish using seine nets. Most fishing resources are exploited according to a centralized management model, whose main regulations are aimed at restricting the fishing effort (establishing seasonal closures, limiting the gear size or the fishing daily hours) and the minimum commercial size.
In 1992 Galicia established a co-management system for shellfish based on the assignment of territorial use rights (TURFs) to local fishers’ organizations according to the historical spatial pattern of fleet activity, and on limiting fisheries access to a given number of boats (and persons if the resources are collected from the shore) belonging to the local fishers’ organizations co-managing each particular stretch of coast. In addition, fishers’ organizations must propose additional regulations for their territories by drawing up annual exploitation plans (including fisher/boat daily quotas, total number of fishing days, marketing strategies, etc.), which have to be finally supervised and accepted by the regional government (
Our study took place in the Cíes Islands, located in the outer area of the Ría de Vigo (
The fieldwork started in February 2009 with the interview of a random sample of fishers about fishing gears that they used in 2008 and ones that were used in the Cíes Islands for at least one month. Fishers were initially approached in Cangas because it is the closest port to the Cíes Islands, and then in the ports located to the north and south, until no more boats working in the Cíes Islands could be found. We stopped the surveys in the ports of Cambados (north of Cangas) and A Guarda (south of Cangas), covering around 195 km of coastline. Because the landing time depends on the type of fishing gear, we visited the ports at different times.
We finished the surveys in each port when we obtained a confidence interval of 95% on the percentage of vessels fishing in the Cíes Islands per gear. The number of surveys required (n=424) was estimated by applying the central limit theorem, whereby a binomial distribution (fishing in the Cíes Islands or not) can be approximated by a normal distribution for large sample sizes.
The fleet size operating in the Cíes Islands was estimated by applying the percentage of respondents who were fishing in the study area to the total number of fishing licences. The total number of licences per fishing gear and port, as well as the technical characteristics of the vessels (length, tonnage and engine), is public information that is available on the web platform “Pesca de Galicia” (
Then we described the fleets according to their area of origin and the fishing gears that they used. The fleet was also divided into three segments according to the Scientific, Technical and Economic Committee for Fisheries of the European Commission and its data collection framework (DCF) used until 2010: artisanal (vessels of less than 12 m length using active and passive gears), polyvalent (boats of between 12 and 24m length using passive gears), and purse seiners (boats between 12 and 24m length using seine nets).
When we had estimated the fleet size of the Cíes Islands, we interviewed 20% of the boats from different ports that fished in the Cíes Islands with each gear. Informants (n=96) were interviewed individually on the dimensions of the gear (see below, “Quantifying the fishing effort” section), the season in which the gears were used, and monthly catch weights by species obtained with each of them.
Catch data were analysed separately per gear in order to identify the different fishing strategies performed with each one. The analyses were performed for gears with a representation higher than 3% in the Cíes Islands, and therefore we had information from at least five interviews per fishing gear. All fishing operations carried out with a mono-specific gear were considered part of the same fishing strategy. Regarding multi-species gears, the strategies were identified by applying multivariate analysis techniques on the basis of the catch composition (
Then, we carried out a hierarchical cluster analysis using Chord distances as a dissimilarity index and the minimum variance criterion of
We described the fleet dynamics through the seasonal variability in the use of the fishing strategies. In addition, we studied the combination of strategies most frequently used by identifying groups of vessels with similar fishing activities throughout the year. Following the methodology proposed by
Nominal fishing effort depends on the duration of the fishing activity and the fishing capacity (
We estimated the fishing effort (FE1) as the product of the gross tonnage (GT) and the average number of fishing days in the Cíes Islands for each fleet segment (artisanal, polyvalent and purse seiners):
where i=1, …, n interviewed vessels, and N is the estimated number of boats fishing in the Cíes Islands.
The fishing effort estimated by means of this equation allows to interpret the level of fishing pressure exerted over the fishing area, and it is often used to regulate fishing capacity in order to minimize overfishing. However, this measure does not reflect the level of activity carried out at a fishery scale. In this regard, the fishing effort estimated by means of gear characteristics is easily related to fishing mortality, thus being more applicable to estimating catch and monitoring stock trends (
This latter effort indicator (FE2) was only estimated for the strategies used by artisanal boats, which share similar technical characteristics. Purse seiners, in addition to their different technical characteristics, are often equipped with advanced technology to detect and attract fish, which clearly increases the fishing efficiency of the gear. Since we did not have sufficient information to include these factors in the indicator, the effort exerted by purse seiners was only estimated through FE1. The polyvalent segment has very little representation in the study area (2.5% of the fleet in Cíes), so it was also removed from this estimation. Comparisons of the fishing effort associated with the strategies within each type of gear were performed by means of a one-way analysis of variance (ANOVA). The fishing effort was log transformed to correct the heteroscedasticity of the data.
All analyses were carried out with the R 3.1.1. programming language (
A total of 565 boats (515 artisanal, 15 polyvalent and 35 purse seiners) fish around the Cíes Islands for at least one month a year. The fleet comes from 11 ports of southern Galicia (
According to the surveys (n=424), 78.1% of artisanal and polyvalent fleet is allowed to use 4 or 5 gears, although only 6.2% use all authorized gears. Of the vessels fishing in the Cíes Islands, 64.8% fish with two or three gears and half fish with only one gear. On average, each boat has a fishing licence to use 4.14 (±0.05 SE) different gears, but they only use 2.22±0.05 routinely, and they only fish in the Cíes Islands with 0.91±0.05 of them.
We identified 19 gears operating in the Cíes Islands (
Gear | No licences | No surveys | Fleet in Cíes Islands | % fleet in relation to the total of Cíes | |||||
---|---|---|---|---|---|---|---|---|---|
Local name | Code | English name | % | No vessels | CI 95% | ||||
Betas | BE | Set gillnets | 271 | 136 | 25.7 | 69.7 | 57.5 | 85.5 | 8.7 |
Boliche | BO | Small-mesh trawls | 87 | 40 | 30.0 | 26.1 | 18.8 | 36.3 | 3.3 |
Bou de man | BM | Large-mesh trawls | 40 | 17 | 29.4 | 11.8 | 7.3 | 19.1 | 1.5 |
Cerco | CE | Purse seines | 49 | 25 | 72.0 | 35.3 | 28.2 | 39.6 | 4.4 |
Endeño remolcado* | EN | Mechanized clam rakes | 16 | 8 | 62.5 | 10.0 | 6.7 | 12.1 | 1.3 |
Liña | LI | Handlines | 263 | 79 | 7.6 | 20.0 | 11.1 | 39.0 | 2.5 |
Miños | MI | Large-mesh trammel nets | 300 | 148 | 30.4 | 91.2 | 76.9 | 108.4 | 11.4 |
Nasa camarón | NC | Pots targeting shrimps | 275 | 98 | 5.1 | 14.0 | 7.7 | 29.4 | 1.8 |
Nasa fanequeira | NF | Pots targeting pouts | 8 | 5 | 40.0 | 3.2 | 3.2 | 3.2 | 0.4 |
Nasa nécora | NN | Pots targeting velvet crab | 449 | 205 | 20.5 | 92.0 | 76.0 | 112.7 | 11.5 |
Nasa polbo | NP | Pots targeting octopus | 400 | 191 | 26.7 | 106.8 | 90.4 | 126.7 | 13.4 |
Navalla* | NV | Razor clam harvesting | 17 | 13 | 100.0 | 17.0 | 14.3 | 17.0 | 2.1 |
Ourizo* | OU | Sea urchin harvesting | 7 | 7 | 71.4 | 5.0 | 0.0 | 0.0 | 0.6 |
Palangrillo | PA | Set and bottom longlines | 153 | 84 | 19.0 | 29.1 | 22.5 | 39.8 | 3.7 |
Percebe* | PE | Goose barnacle harvesting | 34 | 21 | 100.0 | 34.0 | 29.2 | 34.0 | 4.3 |
Racú | RA | Artisanal purse seines | 5 | 5 | 80.0 | 4.0 | 4.0 | 4.0 | 0.5 |
Rastro bivalvos* | RB | Manual clam rakes | 341 | 139 | 41.0 | 139.8 | 119.4 | 161.9 | 17.5 |
Trasmallos | TR | Small-mesh trammel nets | 347 | 139 | 17.3 | 59.9 | 45.8 | 79.9 | 7.5 |
Xeito | XE | Drifting gillnets | 140 | 58 | 22.4 | 31.4 | 22.3 | 45.1 | 3.9 |
TOTAL | 3202 | 1418 | 800.4 | 641.3 | 993.8 | 100.0 |
The fishing gears most commonly used in the Cíes Islands are manual clam rakes (RB in
From the information obtained in the interviews (n=96), we analysed the catch profile of the gears. Except for drifting gillnets, we identified more than one possible catch profile for each multi-species gear, which indicates the existence of different fishing strategies (
Gear and strategy | No interviews | No observations | Target species | Accessory species |
---|---|---|---|---|
BE | 22 | 91 | ||
Be_1 | 6 | 17 | ||
Be_2 | 12 | 58 | ||
Be_3 | 5 | 16 | ||
BO | 6 | 22 | ||
Bo_1 | 2 | 9 | ||
Bo_2 | 4 | 13 | ||
CE | 7 | 72 | ||
Ce_1 | 6 | 35 | ||
Ce_2 | 5 | 18 | ||
Ce_3 | 5 | 19 | ||
EN | 3 | 10 | ||
En_1 | 3 | 10 | ||
MI | 21 | 141 | ||
Mi_1 | 3 | 12 | Soleidae (12%), |
|
Mi_2 | 3 | 13 | ||
Mi_3 | 6 | 23 | Soleidae (53%) | |
Mi_4 | 11 | 31 | Soleidae (13%) | |
Mi_5 | 11 | 45 | ||
Mi_6 | 4 | 13 | ||
Mi_7 | 2 | 4 | ||
NC | 1 | 12 | ||
Nc_1 | 1 | 12 | ||
NF | 1 | 8 | ||
Nf_1 | 1 | 8 | ||
NN | 23 | 121 | ||
Nn_1 | 23 | 121 | ||
NP | 27 | 158 | ||
Np_1 | 27 | 158 | ||
NV | 8 | 85 | ||
Nv_1 | 8 | 85 | ||
OU | 4 | 25 | ||
Ou_1 | 4 | 25 | ||
PA | 6 | 38 | ||
Pa_1 | 1 | 12 | ||
Pa_2 | 4 | 20 | ||
Pa_3 | 1 | 6 | ||
PE | 10 | 108 | ||
Pe_1 | 10 | 108 | ||
RB | 18 | 119 | ||
Rb_1 | 5 | 17 | ||
Rb_2 | 8 | 45 | ||
Rb_3 | 10 | 57 | ||
TR | 11 | 53 | ||
Tr_1 | 7 | 23 | ||
Tr_2 | 3 | 17 | ||
Tr_3 | 3 | 13 | ||
XE | 6 | 23 | ||
Xe_1 | 6 | 23 |
At least 33 fishing strategies are used in the Cíes Islands (the multi-species gears BM, LI and RA have not been analysed because of the lack of data). The strategies used by the largest number of boats are Np_1 (pots targeting octopus), Nn_1 (pots targeting velvet crab), Be_2 (set gillnets targeting pouting and hake), Mi_4 (large-mesh trammel nets targeting European spider crab) and Mi_5 (large-mesh trammel nets targeting ballan wrasse), although some of them are employed for very short periods of time. For this reason, the results are different when we analyse the number of observations during the interviews (strategy employed per boat and month), in which case the most important strategies were Np_1, Nn_1, Pe_1, Nv_1, Be_2 and Rb_3 (
Artisanal and polyvalent boats use between 1 and 7 (2.2±0.1) fishing strategies per vessel throughout the year, with many possible combinations of strategies. Despite the wide variety of resulting fishing patterns, we identified 12 groups of vessels with similar annual activity by means of a multivariate analysis (
The fishing dynamics of the generalist vessels can be better understood if the combinations of strategies and their temporal use are analysed together.
The fishing capacity, in terms of engine power, number of crew and length of vessels, increases from artisanal to polyvalent up to the purse seine vessels (See Table 2 in
The differences observed in the fishing effort between strategies were caused by variations in both the number of fishing days and the size of the gears (
Regarding the S-fisheries, the fishing effort exerted on gooseneck barnacles (Pe_1) and razor clams (Nv_1) was higher (F=7.56, p<0.01) because of the large number of fishing days in the Cíes Islands: 90±15 and 138±23 days, respectively. We did not find significant differences between the fishing strategies carried out with hooks (F=8.17, p=0.11) or trawls (F=2.38, p=0.26), but some of these data (specifically data of Pa_1 and Bo_1) should be interpreted with caution because they were estimated from a single interview.
Through the dialogue with fishers, we identified the fleet in an area of special ecological interest in Galicia, the fishing dynamics and the effort associated with each fishing strategy. This information is essential for implementing the EAF, because it reveals how the fishing effort is allocated in space and time, its impact on the resources, and how the fleet will respond to a change in the ecosystem or a new management regulation.
Our results highlight the complexity of the fishery system in Galicia, dominated by artisanal vessels that can use up to five different gears. Since the fishing licence is transferable with the boat, fishers aspire to include many gears in their fishing permit to increase the value of the boat, although they do not actually intend to fish with them. In fact, artisanal fishers estimate that their fishing licence represents almost 40% of the value of the boat, and the value is even higher if the gears belong to the group of S-fisheries (
Although some of the gears used by the artisanal and polyvalent fleet in Galicia are highly selective (e.g. pots and manual collection techniques), the catch composition varies greatly in most of the cases depending on the fishing area, season and mesh size. The combination of these factors generates a diversity of fishing strategies targeting different species that add complexity to the fishery system.
Despite the socio-economic importance of the fisheries in Galicia, to our knowledge this is the first study analysing the fishing strategies in this region. In fact, the articles identifying fishing strategies in Spain were performed in the Mediterranean and/or southern areas of the country (
This wide variety of fishing strategies, with noteworthy differences in catch composition and temporal distribution, suggests that the actual effort invested in the resources cannot be only estimated per gear. If it were, an increase in the number of vessels using large-mesh trammel net, for example, would be interpreted as an increase in the fishing mortality of European spider crab (target species in terms of catch weights at gear level), whereas in fact the harmed species depends on the fishing strategy in which the increased effort takes place. Consequently, spatial and temporal data of fishing effort at strategy level are fundamental to understand the impact on resources and ecosystems, and to establish suitable management regulations accordingly.
The fact that most of the fleets are generalist using several strategies throughout the year adds a higher level of complexity in the fisheries’ functioning. The choice of fishing strategy depends on a host of variables whose ultimate goal is to increase the economic performance. The local knowledge on the spatial-temporal migration dynamics of target species, the temporal variations in recent catches, the weather, the personal preferences of the skipper, the fish prices, the fishing regulations, and the gears they are allowed to use from their licence are some of the influential aspects in the selection of fishing strategy, and ultimately in the temporal pattern of the fishing activities (
Understanding these fishing patterns and their distribution in space is essential to reduce the uncertainty associated with fishers’ behaviour and carry out effective management actions within the EAF. For example, the EU is currently considering banning drift gillnets. How would this measure affect the ecosystem? Which fleet would be harmed with this measure? Which one would be benefited? These questions can only be answered by knowing the ecosystem functioning and the fleet dynamics. Specifically this legislative change, whose aim is to increase the biomass of sardine, would not produce great achievements in our study area since sardine catches from drift gillnets are very small compared with those from purse seines (unpublished data). However, assuming that the biomass of sardine will increase, a greater abundance of predators such as hake should be also expected, so the fleet of large-mesh trammel nets and set gillnets could be benefited. On the other hand, the fleet of drift gillnets would begin to fish other resources. According to the fishing patterns identified in this study, the prohibition of this gear would be associated with an increase in the fishing effort by manual clam rakes (group 7 in
Regarding fishing effort, this study concludes that 565 vessels, most of them artisanal, fished in the Cíes Islands in 2008. This number is high when compared with that in other regions with similar ecological interest. Between 9 and 13 artisanal vessels fish in an area of 12.2 km2 within the French National Park of Port Cross (
Many fishing regulations of the Galician fisheries are based on restricting the fishing effort through the dimensions of the gears, but these regulations are difficult to enforce. Comparing the size of the gears used in the Cíes Islands with the maximum capacity allowed by law at that time, we found that 35% of the vessels did not respect the rules. This percentage is probably even higher since some fishers might have hidden the truth during the interview. According to information provided by the fishers, the legal dimensions of the gears were exceeded by 200 hooks (information from one vessel), 154.5±25.6 pots (15 vessels), 2.3±0.6 km of net (20 vessels) and 57.7±32.4 m of length of the wing net (3 vessels). The problem is not only that the enforcement mechanisms are not sufficient, but also that the management system is not adapted to the changing and complex reality that fishers must face, and consequently they break the rules. A higher participation of fishers in the management system, as well as the development and implementation of data collection programmes that include fleet dynamics and spatial information, are key factors to create an adaptive governance system and carry out a management consistent with the complexity of the fisheries.
We gratefully acknowledge financial support from the Spanish Ministry of the Environment, the European Regional Development Fund and the Spanish Juana de Vega Foundation. We would like to thank the National Marine Park of the Atlantic Islands of Galicia and the “Consellería do Mar” of the Autonomous Government of Galicia (“Xunta de Galicia”) for their cooperation. Special thanks to the fishing cooperative “Cofradía de Cangas” and all the fishers involved for the valuable information they provided. Finally, we thank two anonymous reviewers for their helpful comments and suggestions.