© 2006 International Council for the Exploration of the Sea
Relationships between wave exposure and biomass of the goose barnacle (Pollicipes pollicipes, Gmelin, 1790) in the Gaztelugatxe Marine Reserve (Basque Country, northern Spain)
AZTI Foundation, Department of Oceanography and Marine Environment Herrera Kaia, Portualdea s/n, 20110 Pasaia, Spain
*Correspondence to Á. Borja: tel: +34 943004800. e-mail: aborja{at}pas.azti.es.
Marine protected areas play an important role in the conservation of marine resources and fisheries management. In the Basque Country (northern Spain), the small (158 ha) Gaztelugatxe Marine Reserve was established in 1998; after 5 years without exploitation, it is considered likely that the goose barnacle Pollicipes pollicipes populations have recovered. This contribution provides information on the standing stock, and of the relationships between biomass, coverage, and density, and environmental factors such as wave height and energy derived from waves received at the coast. Increasing energy levels produce enhanced coverage and abundance, providing a bigger standing stock in the reserve. Numerical models to simulate the energy produced by waves can be used as a tool to predict the potential biomass of the goose barnacle along the coast. Such an approach allows comparison of observed and predicted biomasses, and possibly also determination of the factors involved in the observed differences, e.g. overexploitation and pollution; this will assist in assessing goose barnacle resources along the coast.
Keywords: assessment, benthic resources, biomass, goose barnacle, marine reserve, wave exposure
Received 30 January 2004; accepted 28 December 2005.
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Introduction |
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The World Conservation Union proposed conserving 20% of the world's coastline within marine protected areas by the year 2000 (IUCN, 1992). In the case of the Basque Country (northern Spain), the Basque Department of Agriculture and Fisheries decided, in 1998, to create the small (158 ha) Gaztelugatxe Marine Reserve (229/1998 Decree of 15 September, of the Basque Government). The aspects taken into account in protecting the area were the overexploitation of the goose barnacle (Borja et al., 2000), and the subsequent damage of the associated communities, as described in other countries (Jamieson et al., 1999), and benthic species (Maliao et al., 2004). Therefore, the marine protected area recognizes the importance for fisheries management of conserving ecosystem structure as a basis for stable fishery production. The reserve also has value in providing an undisturbed area for comparative studies (Attwood et al., 1997).
In Gaztelugatxe, the depletion of the goose barnacle provoked a prohibition on exploitation inside the Marine Reserve and, as such, several studies were undertaken (Borja et al., 2004). After 5 years of protection, the differences in density, biomass, size, and weight of individual goose barnacles, within and outside the protected area, were examined (Borja et al., in press).
However, little is known about goose barnacle standing stocks anywhere and particularly about any relationships between abundance and environmental factors. Girard (1982) studied the stocks in Brittany (France), Molares (1998) and Molares and Freire (2003) studied those of Galicia (Spain), Lauzier (1999a, b) collated data from Canadian stocks, and Barnes (1996) reviewed the global situation, including environmental factors. The species inhabits the most exposed cliffs and reefs, in areas facing the open sea, where waves break with extreme violence (Barnes, 1996).
This contribution evaluates the biomass in the Gaztelugatxe Marine Reserve after 5 years without exploitation, establishing relationships between marine climate (wave energy) and biomass. These results are compared with the situation in unprotected areas and as a tool in the management of exploited stocks.
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Methodology |
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TopIntroductionMethodologyResultsDiscussionConclusionsReferences |
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Standing stock evaluation
Standing stock evaluation within the Gaztelugatxe Marine Reserve was undertaken on Aketze Island, Gaztelugatxe tombolo, and on the rocks between this area and Bakio. In all, 11, 10, and 4 sampling locations were studied in each area, respectively (Figure 1c).
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At each location, goose barnacle coverage was determined visually, including an area extending to 5 m on either side of the biomass sampling station (see below). The coverage was recorded according to the following scale:
- without goose barnacle;
- solitary individuals, coverage <5% (mean 2%);
- presence only inside cracks, small groups of barnacles, coverage 6–15% (mean 10%);
- presence of relatively separated aggregations, in rocks and cracks, coverage 16–35% (mean 25%);
- presence of close aggregations (<0.5 m) in rocks and cracks, coverage 36–65% (mean 50%); and
- continuous coverage, very abundant in rocks and cracks, coverage 66–100% (mean 75%).
At each sampling location, the data collected were the following: (i) intertidal height (measured in m above the Lowest Astronomical Tide, LAT) at which the goose barnacle was not present; (ii) subtidal depth (in m below LAT) at which the goose barnacle was not present; (iii) coastal orientation; and (iv) the bandwidth, in m, of the goose barnacle (i + ii). The subtidal depth was measured with a depth metre, and then corrected with tide height.
In order to determine biomass and density, samples were collected at four locations within each area (rocks; Gaztelugatxe; Aketze, see Figure 1c). This was achieved by scraping four 30 x 30 cm quadrats, two intertidally and two subtidally, adapting the De la Hoz and García (1993) methodology. The sampling was undertaken on 22 August 2002.
In the laboratory, the barnacles were sorted and counted, including both adults and juveniles (those <10 mm capitulum length, according to Cruz, 1993). Fresh weight was determined for each sample. The total coastal length occupied by the goose barnacle was derived from maps of scale 1:5000.
The methodology used in calculating the standing stock was similar to that used for other sessile benthic populations, such as algae (Mann, 1972; Niell and Soneira, 1976; Borja, 1987). Hence, the process was to determine biomass per m2 in a series of samples (B), corrected by coverage; the distribution bandwidth of the goose barnacle (at the intertidal and subtidal levels), BW; the total coastal length occupied by the goose barnacle (L); and the standing stock by area and in the whole marine reserve, from B x BW x L.
Marine climate
In order to facilitate the study of the relationships between biological and environmental factors, the coast was divided into homogeneous sectors (depending upon their orientation; Figure 1d), in which the marine climate parameters were determined.
The main mean marine climate parameters in each sector were determined by the MANOLO (Modelo Avanzado No Lineal de Ondas, or Non-Linear Wave Advanced Model) software, developed by the Coastal Engineering Group of Cantabria University (GIOC), with the collaboration of AZTI (University of Cantabria and Cornell University, 2003). The software solves the elliptic form of the mild-slope equations (Berkhoff, 1972), using the finite elements technique. It is used especially in the study of harbour agitation, because it simulates the wave propagation in shallow water (including shoaling effects, refraction, diffraction, breaking, and reflection) with well-defined vertical contours. In the Gaztelugatxe Marine Reserve, the rocky coastal cliffs are practically vertical (Borja et al., 2000) and wave reflection plays an active role, so the MANOLO software is an appropriate simulation tool.
In order to simulate wave propagation, detailed bathymetry of the area was used (Borja et al., 2000). The land contours were defined following the coastal and island profiles, being vertical above 0 m LAT; likewise, using different reflection coefficients depending upon morphology (for details, see Borja et al., 2004). Further, there are two straight contours, simulating the adjacent sea, and an external crown, simulating the external sea, all with a reflection coefficient of 0 (Figure 2). The crown serves to introduce the forcing mechanism (waves), establishing the grid used in the model.
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The wave data were obtained from the ODIN programme (Coastal Directorate, Spanish Ministry of Environment), which is publicly accessible at www.puertos.es; this provides mean and extreme wave data for any Spanish coastal location on the basis of an historical measurement series. Hence, selecting all data from an area with 150 km of radius, for a mean water depth of 30 m in the crown, the percentage of waves was calculated (Table 1). For additional details about this methodology and the original data set, see González et al., (2004). In this contribution, 11 monochromatic wave regimes are propagated, including different wave directions, heights, and periods, representing the regional mean wave pattern on the basis of their most representative components: (i) NNW – wave height (Hs) 1 m, and wave period (Tp) 10 s, and Hs 2 m, Tp 12 s; (ii) NW – Hs 1 m, Tp 12 s, and Hs 2 m, Tp 14 s, and Hs 4 m, Tp 14 s; (iii) WNW – Hs 1 m, Tp 12 s, and Hs 2 m, Tp 14 s, and Hs 4 m, Tp 14 s; and (iv) N, NNE, and W – Hs 1.5 m, Tp 7 s. These regimes were selected because previous studies undertaken in the Basque Country (González et al., 2004) established the dominance of waves (swell) from the northwest (25%); these are also the highest over the whole region, 77% of the waves over the area originating from the fourth quadrant (270°–360°N).
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The wave energy received by sector width was calculated from
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is the seawater density (1025 kg m–3), g the gravity (9.81 m s–2), H the wave height (m), and L is the wavelength (m). The wavelength in the vicinity of each sector studied is a function of the simulated wave period and the mean water depth over the area, calculated from
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Results |
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Standing stock evaluation
The coverage in the area is high, showing a logarithmic regression with biomass (Coverage = 1.66 ln(FW) – 5.86; coverage in % and FW in kg m–2). This relationship explains 61.4% of the variability, showing an asymptotic trend in coverage.
The coverage and the distribution of goose barnacles at the intertidal and subtidal levels of the Gaztelugatxe Marine Reserve are shown in Figure 3. The greatest coverage, values of 4–5 (36–100%), was on NW-orientated coasts, coverage decreasing progressively towards the northeast and the west, reaching their lowest values (1 or 2; <15%) in the S, SE, and SW.
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There is a distributional pattern in intertidal height reached by the barnacles. Hence, in the N-NW, bandwidth reached 3 m above LAT, compared with just 1.5–2 m in the S-SE. Likewise subtidally, goose barnacles reached a water depth of 1.5 m along N-NW-orientated coasts, although no barnacles were found subtidally along S-orientated coasts. In general, the greatest coverage was in areas with difficult terrestrial access, and highly exposed.
The data used in the calculation of the standing stock are listed in Table 2. The greatest densities and mean biomasses were obtained for Aketze Island. Likewise, the least mean coverage, both intertidally and subtidally, was in the same area. From these data, the highest stock is at Aketze (3.56 t), followed by Gaztelugatxe (3.45 t), and over the rocks (1.58 t). Most of the stock is contained within the intertidal level: the subtidal stock represented only 1.1, 9.3, and 7.7% of the total in each area, respectively. In the Marine Reserve, a standing stock of 8.59 t was calculated; of this, 94.4% was intertidal.
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Marine climate
Following propagation of all of the wave regimes cited in the Methodology, an example of wave height obtained (from a monochromatic WNW wave) is shown in Figure 4a. This regime concentrates the highest waves in shallow water, producing quasi-stationary waves in the contours where the wave front arrives parallel to the coast. In order to derive a realistic wave regime, a spectral wave was propagated (Figure 4b). In this case, although the results are smoothed, the relative distribution of mean wave heights is similar to those presented in the previous example. Hence, the method used to decompose the mean wave in the reserve into a discreet group of monochromatic waves is valid.
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After simulating all cases proposed in the Methodology, the results were analysed in order to obtain mean wave height and angle of incidence within each sector (Table 3). The most prevalent annual wave regime in the area was from the NW, with 2 m wave height (23.3% of the time), followed by calms (18%), then from the WNW, with 2 m wave height (12.2%; Table 3). The mean results for the area give a different pattern, depending upon sector. Hence, the mean annual wave height received in sectors 4, 8, and 10 was <1 m (with wave incidence angles of around 88°); in sectors 1, 5, and 7, the wave height ranged between 1 and 1.5 m (with angles of 65–73°); and in sectors 2, 3, 6, and 9, the received waves were >1.5 m (with angles of 6–25°; Table 3).
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From these data, the energy calculated by (wave) front width was derived for each sector (Table 4). The energy received by the coast was determined taking into account the incidence angle; it was expressed as energy received per linear m of coast (Table 4). As previously determined in relation to wave height, the less energetic regimes were those with waves <1.5 m, coming from the NNE or the N. The energy increased dramatically with wave height, the highest values with WNW waves and 4 m height (Table 4). The derived mean values indicate that sectors 1, 4, 8, and 10 have (wave) front energy values <200 kJ m–1; sectors 5 and 7 ranged between 200 and 600 kJ m–1; and sectors 2, 3, 6, and 9 had values >600 kJ m–1 (Table 4). The less energetic sector is 4, and the most energetic is 6. The distribution is similar to that produced by wave height (see above). The only difference is in sector 1, which had less energy than expected, probably because of the 60° incidence angle.
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Interrelationship between biological and environmental factors
The correlation between environmental and biological factors is presented in Table 5. The four environmental factors studied (wave height, incidence angle, energy per m of coast, and (wave) front energy) had very high significant correlation with biomass per m of coast (calculated by dividing the standing stock on each of the sectors by the coastal length), and coverage of goose barnacle in the Marine Reserve. The correlation was less with density (but significant) and bandwidth (in this case, the correlations with the incidence angle and wave height were not significant; Table 5). The good correlation between these two biological factors in particular (as with the environmental factor energy) is because, in both cases, the calculation of biomass and energy per m of coast, for example, incorporated the remainder of the factors. However, it is important to note that the two last correlations are very high (Table 5). Hence, the energy received by the coast explains 81% of the variability in biomass per m of coast in undisturbed locations.
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In sectors subjected to <1.5 m mean annual wave height, the biomass never exceeded 2.5 kg m–1 (Figure 5a). In response to increasing wave height, the biomass increased rapidly, mean wave heights of 2 m producing a biomass >10 kg m–1 (Figure 5a). Exponential and linear regression models reveal statistically significant relationships between both variables, explaining 54% and 61% of the variability, respectively.
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In terms of the energy received by the coast, biomass is low when the energy is <200 kJ m–1; this increases linearly when the energy increases (Figure 5b). Wave incidence angles of <20° produced high coverage, the values being low when the angle ranged between 60° and 90° (Figure 5c).
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Discussion |
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The density determined in the Gaztelugatxe Marine Reserve (800–6000 barnacles m–2, with means of 1500–2300 barnacles m–2) lies within the same range as that of Pollicipes polymerus: 1800–3800 barnacles m–2 (Lauzier, 1999a) and 2000–5000 barnacles m–2 (Austin, 1987), for the west coast of Canada.
Conversely, the biomass in the Gaztelugatxe Marine Reserve (a mean of 3.3–4.3 kg m–2, with a maximum of 10.6) is slightly higher than that cited by Bernard (1988) for P. polymerus (mean 2.7 kg m–2 and a maximum of 12) in British Columbia (Canada). Other authors have mentioned, for the same species, values between 0.15 and 1.44 kg m–2 (Lessard et al., 2002), on Vancouver Island (Canada). In Brittany, the values of biomass of P. pollicipes (2–8.8 kg m–2; Girard, 1982) are similar to those at Gaztelugatxe.
In Brittany, the harvest is estimated to be within the range 100–300 t year–1 (Girard, 1982), and in Galicia the harvest is around 100 t year–1, with plans for a future harvest of 600 t year–1 (Molares, 2003). These data suggest high standing stocks in the region, even with overexploitation in several areas and at certain times (Barnes, 1996; Molares and Freire, 2003). There are no comparative values available for the standing stock in other countries. Difficulty of access together with exposure to waves and storms are mentioned by Bernard (1988) as reasons for the impossibility of estimating standing stocks in Canada.
The distribution on rocks is related to wave orientation, which modulates feeding time (Barnes, 1996). In sheltered and subtidal areas, wave stimulation is minimized and Pollicipes disappears (Barnes, 1996); this is shown at Gaztelugatxe, where its density is low, along with biomass and coverage subtidally (only 5.6% of the total standing stock); the same has been demonstrated for nearby areas (Borja et al., in press). The orientation of goose barnacles on the rocks is determined by the micro-topography surrounding each cluster (Lauzier, 1999a). In areas where there is distinct run-off, following wave breaking, the dominant orientation of the animals is the position where the anterior face of the capitula faces the run-off water of the retreating waves, allowing a longer feeding time (Barnes and Reese, 1960). Hence, turbulent mixing and water movement after wave breaking facilitate goose barnacle settlement (Lauzier, 1999a). The high biomass in the most energetic sectors at Gaztelugatxe (those orientated NW, such as sectors 2, 3, 6, and 9; see Figure 1d) agrees with this behaviour pattern. Such a distribution is clear from this work, with wave incident energy being the environmental factor determining the absence, or abundance, of the goose barnacle.
Increasing wave energy could produce an asymptotization in biomass within the regression equation (or even a dome-shaped relationship), because continuous physical disturbance produces "substrata free" space in goose barnacle populations, allowing settlement of other species (Lessard et al., 2002). Such asymptotization has not been demonstrated in the area, because the mean annual wave height in the area does not exceed 2.5 m.
This wave effect also influences the vertical distribution of goose barnacles, as shown by the correlation with bandwidth (which is weaker than with biomass). In exposed areas, the cirripede is distributed within the mid-littoral, ranging from 1 m above the highest tide down to the sublittoral. In Brittany, mean bandwidths of 3–4 m were determined (Girard, 1982), similar to those presented in this contribution (mean 3–3.3 m, maximum 4.3 m). In Portugal, the band is narrower (1.5 m; Cruz, 1993). At Gaztelugatxe, the W-NW-N-orientated sectors have wider bands than those orientated to the south. Hence, areas receiving mean annual waves >1.5 m in height, will present wider bands of goose barnacle distribution. Such a pattern agrees with previous data available for the Basque coast, in which the more wave-exposed areas are associated with significantly higher density and abundance than those that are more sheltered (Borja et al., in press).
There are no significant differences in allometric coefficients, in relation to wave exposure, but the differences are significant when comparing cirral length (longer, with decreasing wave exposure; Marchinko and Palmer, 2003); this suggests differences in the ability to capture prey. Marchinko and Palmer (2003) showed that 92% of the variability in the peduncle length is explained by wave exposure.
The strong correlation between wave energy and biological factors such as biomass or coverage is of interest to resource assessment and management. Hoffman (1989) and Lauzier (1999a) consider that recolonization of denuded substrata takes between 7 months and several years. The present study has been undertaken in a protected (i.e. not exploited for 5 years) area; hence, this provides data under "undisturbed" conditions. Following the same procedure, it is possible to establish the wave energy received by disturbed coastal sectors, and possibly also to determine the probability of occurrence of goose barnacles, predicting potential biomass and coverage. The difference between predicted and determined biomasses can assist in calculating the biomass eliminated by exploitation, or of other impacts, such as pollution.
Following the methodology explained in this contribution, the energy received by the exploited coastal areas in the surroundings of the Gaztelugatxe Marine Reserve was calculated on the basis of previous data sets (Borja et al., 2004). Then, according to the relationship established between biomass and energy (see the regression in Figure 5b), the predicted biomass per m of coast in the exploited areas of Izaro and Ogoño (see Figure 1b, for locations) was calculated (Table 6). Both areas and coastal orientations (west and east, see Borja et al., 2004) have biomasses less than expected on the basis of the energy received. In the case of Izaro, the observed biomass ranges between 3.3 and 12.5 times less than predicted levels. Likewise, in Ogoño, the observed biomass per m of coast is between 3.1 and 6 times less than predicted. This result agrees with that obtained by Borja et al. (in press), who compared protected and exploited locations and detected overexploitation at Izaro and Ogoño; this was based upon biomass, density, allometry, and data on the juvenile/adult mix. The Fisheries Service of the Basque Government confirmed this overexploitation. Izaro Island is more accessible than Ogoño Cape (with its vertical cliffs), so exploitation is greater at the first location, as demonstrated also by Borja et al. (in press). Conversely, the observed biomass is less than predicted along the east-orientated than along the west-orientated coast at both locations. This pattern could be related to the more sheltered east coast providing more time for exploitation than exposed areas. A similar pattern has been detected elsewhere (Girard, 1982).
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Conclusions |
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The distribution, coverage, and biomass of goose barnacles in the Gaztelugatxe Marine Reserve, in the absence of man-induced disturbance, are governed by the wave regime and the energy received in each coastal sector. Hence, increasing values of energy produce increasing coverage and abundance, providing a greater standing stock in the Reserve (here calculated as 8.6 t). The biggest biomasses were in areas orientated NW.
The numerical models to simulate the energy produced by waves can be used as a tool in predicting potential biomass of goose barnacles along exploited or unexploited coasts. This conclusion allows comparison between observed and predicted biomasses and determination of the factors involved in such differences, e.g. overexploitation and pollution, and, further, development of an assessment of goose barnacle stocks.
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Acknowledgements |
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The study was supported by a contract undertaken between the Department of Agriculture and Fishing of the Basque Government and AZTI. One author (PL) was supported by a grant from the AZTI Foundation, another (IM) by a grant from the Technological Centres Foundation of the Basque Country. We also thank Professor Michael Collins (School of Ocean and Earth Science, University of Southampton, UK) and Manuel González (Department of Oceanography and Marine Environment, AZTI) for their advice. Finally, we gratefully acknowledge the efforts of the AZTI sampling team and technicians, and Eneko Bachiller and Unai Otxotorena for helping with the sampling and the laboratory work. The comments of two anonymous reviewers improved the final contribution.
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Attwood C.G., Mann B.Q., Beaumont J., Harris J.M. (1997) Review of the state of marine protected areas in South Africa. South African Journal of Marine Science 18:341–367.
Austin W. C. (1987) A feasibility study for the commercial harvesting of the goose barnacle Pollicipes polymerus. Final report prepared by NOPSA Enterprises Ltd and Khoyatan Marine Laboratory for the Department of Fisheries and Oceans. 171 pp.
Barnes M. (1996) Pedunculate cirripedes of the genus Pollicipes. Oceanography and Marine Biology: An Annual Review 34:303–394.
Barnes M. and Reese E.S. (1960) The behaviour of the stalked intertidal barnacle Pollicipes polymerus, J. B. Sowerby, with special reference to its ecology and distribution. Journal of Animal Ecology 29:169–185.[CrossRef][Web of Science]
Berkhoff J. C. W. (1972) Computation of combined refraction–diffraction. Proceedings of the 13th International Conference on Coastal EngineeringASCE 1: pp. 472–490.
Bernard F.R. (1988) Potential fishery for the gooseneck barnacle Pollicipes polymerus (Sowerby, 1833) in British Columbia. Fisheries Research 6:287–298.[CrossRef][Web of Science]
Borja A. (1987) Cartografía, evaluación de la biomasa y arribazones del alga Gelidium sesquipedale (Clem.) Born. et Thur. en la costa guipuzcoana (N España). Investigación Pesquera 51:199–224.
Borja A., Bald J., Muxika I., Liria P. (2004) El recurso marisquero de percebe (Pollicipes pollicipes) en el biotopo marino protegido de Gaztelugatxe y en áreas explotadas de Bizkaia. Informes Técnicos (Departamento de Agricultura y Pesca, Gobierno Vasco) 101: 108 pp.
Borja A., Muxika I., Bald J. Protection of the goose barnacle (Pollicipes pollicipes, Gmelin, 1790) population: the Gaztelugatxe Marine Reserve (Basque Country, northern Spain). Scientia Marina (in press).
Borja A., Valencia V., Castro R., Franco J., Bald J., Uriarte A., Mendizábal M., Aguirrezabalaga F. (2000) Establecimiento de las bases técnicas de conocimiento del área de San Juan de Gaztelugatxe con vistas a su posible declaración como reserva marina. Informes Técnicos (Departamento de Agricultura y Pesca, Gobierno Vasco) 87: 152 pp.
Cruz T. (1993) Growth of Pollicipes pollicipes (Gmelin, 1790) (Cirripedia, Lepadomorpha) on the SW coast of Portugal. Crustaceana 65:151–158.[Web of Science]
De la Hoz J.J. and García L. (1993) Datos para el estudio de la distribución y reproducción del percebe, Pollicipes cornucopiae (Leach), en Asturias. Publicaciones Especiales del Instituto Español de Oceanografía 11:65–71.
Girard S. (1982) Etude du stock de pouces-pieds de Belle-Île et de son exploitation. Mémoire de fin d'études 79 pp.
González M., Uriarte A., Fontán A., Mader J., Gyssels P. (2004) Marine dynamics. In Borja Á. and Collins M. (Eds.). Oceanography and Marine Environment of the Basque Country, Elsevier Oceanography Series(Elsevier, Amsterdam) 70: pp. 133–157.
Hoffman D.L. (1989) Settlement and recruitment patterns of a pedunculate barnacle, Pollicipes polymerus Sowerby, off La Jolla, California. Journal of Experimental Marine Biology and Ecology 125:83–98.[CrossRef][Web of Science]
IUCN. (1992) Caracas action plan. Plenary Session and Symposium Papers of the IVth World Congress on National Parks and Protected AreasCaracas, Venezuela pp. 301–310 World Conservation Union (IUCN), Gland, Switzerland.
Jamieson G. S., Lauzier R. B., Gillespie G. (1999) Phase 1. Framework for undertaking an ecological assessment for outer coast rocky intertidal zone. Fisheries and Oceans Canada, Canadian Stock Assessment Secretariat Research Document, 99/209. 33 pp.
Lauzier R. B. (1999a) A review of the biology and fisheries of the goose barnacle (Pollicipes polymerus Sowerby, 1833). Fisheries and Oceans Canada, Canadian Stock Assessment Secretariat Research Document, 99/111. 30 pp.
Lauzier R. B. (1999b) Framework for goose barnacle (Pollicipes polymerus Sowerby, 1833) fishery in waters off the west coast of Canada. Fisheries and Oceans Canada, Canadian Stock Assessment Secretariat Research Document, 99/198. 24 pp.
Lessard J., Osborne J., Lauzier R., Jamieson G., Harbo R. (2002) Applying local and scientific knowledge to the establishment of a sustainable fishery: the west coast Vancouver island goose barnacle fishery experience. Putting Fishers' Knowledge to Work: Conference Proceedings pp. 36–43.
Maliao R.J., Webb E.L., Jensen K.R. (2004) A survey of stock of the donkey's ear abalone, Haliotis asinina L. in the Sagay Marine Reserve, Philippines: evaluating the effectiveness of marine protected area enforcement. Fisheries Research 66:343–353.[CrossRef][Web of Science]
Mann K.H. (1972) Ecological energetics of the seaweed zone in a marine bay on the Atlantic coast of Canada. 1. Zonation and biomass of seaweeds. Marine Biology 12:1–10.
Marchinko K.B. and Palmer A.R. (2003) Feeding in flow extremes: dependence of cirrus form on wave-exposure in four barnacle species. Zoology 106:127–141.[CrossRef][Web of Science][Medline]
Molares J. (1998) Biología y explotación del percebe (Pollicipes cornucopia) en las costas de Galicia. In Penas Patiño X. (Ed.). Marisqueo en Galicia: 3a Xornadas de Medio Mariño e Acuicultura pp. 135–158 Edicios do Castro, Sada.
Molares J. (2003) Biología del percebe (Pollicipes pollicipes) en las costas de Galicia. http://sigremar.cesga.es/percdin.html.
Molares J. and Freire J. (2003) Development and perspectives for community-based management of the goose barnacle (Pollicipes pollicipes) fisheries in Galicia (NW Spain). Fisheries Research 65:485–492.[CrossRef][Web of Science]
Niell F.X. and Soneira A. (1976) Sobre la biología de Ascophyllum nodosum L. Le Jolis, en Galicia. 2. Biomasa total, estival, en la ría de Vigo. Investigación Pesquera 40:105–110.
University of Cantabria and Cornell University. (2003) MANOLO: Modelo Avanzado Lineal de Ondas. User Manual, ß Version. 87 pp. + Annexes.
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