**Abstract**

The harvesting of littoral benthic shellfish in the archipelago of Madeira dates back to the fifteenth century when the Portuguese discovered and colonized the archipelago. The consumption of littoral shellfish is part of the gastronomic cultural heritage of this region, appreciated by the local population and tourists, and has a high social and economic importance. Therefore, harvesting pressure on these resources is one of the greatest concerns, and as such, a sustainable exploitation based on proper regulation, considering the biological and ecological specificities of these species in their particular habitat, is crucial to promote the preservation of species and habitats at medium and long terms. This study presents the current harvesting management regime for gastropods in the archipelago of Madeira and characterizes the artisanal harvest through a period of 27 years (1990–2017) providing new insights for future research in these topics. This artisanal harvesting operates mostly by small vessels (<10 m), with low tonnage and capacity, in nearby areas preferentially in the North coast of Madeira and around Desertas Islands. During the studied period, management actions resulted in the reduction of 50% of the vessels operating in the harvesting of limpets and in slight recovery of the stocks of limpets. The economic impact of limpets gradually increased over the years, representing in 2017 96% of the economic value landed for molluscs and 2% of the total landings in this region. The present characterization provides a comprehensive outlook of the evolution of the marine gastropod harvest in the archipelago of Madeira and allows future comparisons with other regions where gastropods are commercially exploited.

**Keywords:** harvesting, management, sustainable exploitation, limpets, topshells, archipelago of Madeira

## **1. Introduction**

The artisanal fisheries of marine invertebrates in the archipelago of Madeira (NE Atlantic) target mainly gastropods and cephalopods. The main gastropod

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3266. Viii. 2018. 245 p

*Invertebrates - Ecophysiology and Management*

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[7] Marliave J, Gibbs DM, Young S, Borden L. 2011 climate regime: Revealed by seabed biodiversity. In: Chandler PC, King SA, Boldt J, editors. State of the Physical, Biological and Selected Fishery Resources of Pacific Canadian Marine Ecosystems in 2017. Canadian Technical Report of Fisheries and Aquatic Sciences species harvested are the limpets *Patella aspera* Röding, 1798, and *Patella candei* d'Orbigny, 1840, the topshell *Phorcus sauciatus*, and the whelk or redmouthed rocksnail *Stramonita haemastoma*. Regarding cephalopods, the common octopus *Octopus vulgaris* Cuvier, 1797; the squid European *Loligo vulgaris* Lamarck, 1798; and the orangeback squid *Sthenoteuthis pteropus* (Steenstrup, 1855) are the main target species of this fishery. Additionally, the cuttlefish *Sepia officinalis* Linnaeus, 175, and the European flying squid *Todarodes sagittatus* (Lamarck, 1798) are sporadically captured.

The artisanal harvest of gastropods in the archipelago of Madeira is a low-cost activity, usually carried out by the owner of the vessel accompanied by professional snorkelers. This activity is one of the most important small-scale fisheries in this region, due to the economic and social benefits it provides directly to the coastal communities and indirectly to the whole community. This fishery dates back to the fifteenth century when the Portuguese colonized the archipelago. The good accessibility to the rocky shores prompted the exploitation of marine shellfish resources along the coast. The harvest activity becomes progressively more intensive with the demographic increase of human settlement around the islands' coasts and with the technological progresses that simplify the access to the coast at previously inaccessible areas [1, 2]. This long-term exploitation has changed the population dynamics, due to shifts on the abundance and/or size structure and density of the exploited marine gastropods over the years [3].

In the past, four species of the genus *Patella* were reported for the archipelago of Madeira, namely *Patella aspera* as the most abundant species, *Patella caerulea*, *Patella lusitanica*, and *Patella vulgata* (known locally as "concharéu" due to its large size, sharp edges, and helmet shape). The distribution of *P. candei* (formerly identified as *P. vulgata*), which once occurred in all the islands of the archipelago, became restricted, in the beginning of the twentieth century, to the Selvagens Islands [1]. Presently, *P. aspera* and *P. piperata* (formerly identified as *P. lusitanica*) are common species in all islands from the archipelago of Madeira, *P. candei* (formerly identified as *P. caerulea*) is present in Madeira Island, Porto Santo, and Desertas, while the real *P. candei* is restricted to the Selvagens Islands. Recently new molecular tools developed with novel microsatellite markers using next-generation sequencing suggest the use of *P. candei* for the species from the Selvagens and *Patella ordinaria* for the species of Madeira, Desertas, and Porto Santo islands [4].

Concerning topshell exploitation, two species of the genus *Phorcus* have been harvested in Madeira archipelago since early colonization times. *Phorcus sauciatus* (formerly identified as *Trochus colubrinus* Gould, 1849), the most common species and with a wider geographical distribution, occurring in all islands of the Madeira archipelago, and *Phorcus atratus* are restricted to the Selvagens Islands as the endemic subspecies *Phorcus atratus selvagensis* [5]. Nowadays, *P. sauciatus* continues to be exploited in Madeira, Porto Santo, and Desertas, except in the marine protected areas (MPAs), and *P. atratus selvagensis* is not commercially exploited since its distribution is restricted to the MPA of the Selvagens where harvesting is not allowed.

Both limpet consumption and topshell consumption in Madeira archipelago are part of the gastronomic cultural heritage of this region, appreciated by the local population and tourists alike, and have a high socioeconomic importance. Therefore, harvesting pressure on these resources is one of the greatest concerns. As such, a sustainable exploitation, based on suitable regulation considering the biological and ecological specificities of these species in their particular habitat, is crucial to promote the preservation of species and habitats at medium and long terms.

The aim of present work is to compile and characterize the harvest of limpets and topshells in the archipelago of Madeira, considering and discussing the

**149**

**Figure 1.**

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet…*

evolution of the landings and economic values and describing the activity, fishing fleets, exploited species, and yields for a period of 27 years (1990–2017). Additionally, the impact of this activity on selected aspects of limpet and topshell

The implemented management measures regulating the harvest of marine molluscs in the archipelago of Madeira are characterized in detail and their impact on the exploited stocks critically discussed through a comparative analysis of any relevant available data on these species from this region. Finally, the economic and social contextualization of this fishery is made in the overall fisheries sector in the region.

The archipelago of Madeira is located in the northeastern Atlantic Ocean and is included in the Macaronesian biogeographical region together with the Azores, Canary, and Cape Verde (**Figure 1**). The islands of these archipelagos are of volcanic origin, resulting from the activity of several geological hotspots and sharing the oceanic nature, the geographic location, and the climatic regime. However, with specific characteristics according to the proximity of the islands to the mainland regions [6]. The archipelago of Madeira comprises the islands of Madeira (741 km2

island of Madeira is located approximately at 635 km from Morocco and at 900 km from the Portuguese mainland. The Selvagens islands are the southernmost territory of Portugal at 239 km from the island of Madeira and at 375 km from the coast of Morocco. This subtropical archipelago is influenced by the Azores anticyclone, the Gulf and the Canary currents, the continental anticyclonic center of Northwest Africa and Western Europe, and the frontal systems associated with the lower pres-

*Representation of the southern part of the Northeastern Atlantic showing the study area, the archipelago of* 

*Madeira, included in the Macaronesian biogeographical region.*

), and the Selvagens islands (3 km<sup>2</sup>

of area),

). The

*DOI: http://dx.doi.org/10.5772/intechopen.85728*

**2. Study area**

Porto Santo (42 km<sup>2</sup>

sure center of the polar front [7].

population dynamics is analyzed and discussed.

), Desertas (14 km<sup>2</sup>

*Artisanal Harvest of Shellfish in the Northeastern Atlantic: The Example of Limpet… DOI: http://dx.doi.org/10.5772/intechopen.85728*

evolution of the landings and economic values and describing the activity, fishing fleets, exploited species, and yields for a period of 27 years (1990–2017). Additionally, the impact of this activity on selected aspects of limpet and topshell population dynamics is analyzed and discussed.

The implemented management measures regulating the harvest of marine molluscs in the archipelago of Madeira are characterized in detail and their impact on the exploited stocks critically discussed through a comparative analysis of any relevant available data on these species from this region. Finally, the economic and social contextualization of this fishery is made in the overall fisheries sector in the region.

## **2. Study area**

*Invertebrates - Ecophysiology and Management*

marine gastropods over the years [3].

species of Madeira, Desertas, and Porto Santo islands [4].

captured.

species harvested are the limpets *Patella aspera* Röding, 1798, and *Patella candei* d'Orbigny, 1840, the topshell *Phorcus sauciatus*, and the whelk or redmouthed rocksnail *Stramonita haemastoma*. Regarding cephalopods, the common octopus *Octopus vulgaris* Cuvier, 1797; the squid European *Loligo vulgaris* Lamarck, 1798; and the orangeback squid *Sthenoteuthis pteropus* (Steenstrup, 1855) are the main target species of this fishery. Additionally, the cuttlefish *Sepia officinalis* Linnaeus, 175, and the European flying squid *Todarodes sagittatus* (Lamarck, 1798) are sporadically

The artisanal harvest of gastropods in the archipelago of Madeira is a low-cost activity, usually carried out by the owner of the vessel accompanied by professional snorkelers. This activity is one of the most important small-scale fisheries in this region, due to the economic and social benefits it provides directly to the coastal communities and indirectly to the whole community. This fishery dates back to the fifteenth century when the Portuguese colonized the archipelago. The good accessibility to the rocky shores prompted the exploitation of marine shellfish resources along the coast. The harvest activity becomes progressively more intensive with the demographic increase of human settlement around the islands' coasts and with the technological progresses that simplify the access to the coast at previously inaccessible areas [1, 2]. This long-term exploitation has changed the population dynamics, due to shifts on the abundance and/or size structure and density of the exploited

In the past, four species of the genus *Patella* were reported for the archipelago of Madeira, namely *Patella aspera* as the most abundant species, *Patella caerulea*, *Patella lusitanica*, and *Patella vulgata* (known locally as "concharéu" due to its large size, sharp edges, and helmet shape). The distribution of *P. candei* (formerly identified as *P. vulgata*), which once occurred in all the islands of the archipelago, became restricted, in the beginning of the twentieth century, to the Selvagens Islands [1]. Presently, *P. aspera* and *P. piperata* (formerly identified as *P. lusitanica*) are common species in all islands from the archipelago of Madeira, *P. candei* (formerly identified as *P. caerulea*) is present in Madeira Island, Porto Santo, and Desertas, while the real *P. candei* is restricted to the Selvagens Islands. Recently new molecular tools developed with novel microsatellite markers using next-generation sequencing suggest the use of *P. candei* for the species from the Selvagens and *Patella ordinaria* for the

Concerning topshell exploitation, two species of the genus *Phorcus* have been harvested in Madeira archipelago since early colonization times. *Phorcus sauciatus* (formerly identified as *Trochus colubrinus* Gould, 1849), the most common species and with a wider geographical distribution, occurring in all islands of the Madeira archipelago, and *Phorcus atratus* are restricted to the Selvagens Islands as the endemic subspecies *Phorcus atratus selvagensis* [5]. Nowadays, *P. sauciatus* continues to be exploited in Madeira, Porto Santo, and Desertas, except in the marine protected areas (MPAs), and *P. atratus selvagensis* is not commercially exploited since its distribution is restricted to the MPA of the Selvagens where harvesting is

Both limpet consumption and topshell consumption in Madeira archipelago are part of the gastronomic cultural heritage of this region, appreciated by the local population and tourists alike, and have a high socioeconomic importance. Therefore, harvesting pressure on these resources is one of the greatest concerns. As such, a sustainable exploitation, based on suitable regulation considering the biological and ecological specificities of these species in their particular habitat, is crucial to promote the preservation of species and habitats at medium and long terms.

The aim of present work is to compile and characterize the harvest of limpets

and topshells in the archipelago of Madeira, considering and discussing the

**148**

not allowed.

The archipelago of Madeira is located in the northeastern Atlantic Ocean and is included in the Macaronesian biogeographical region together with the Azores, Canary, and Cape Verde (**Figure 1**). The islands of these archipelagos are of volcanic origin, resulting from the activity of several geological hotspots and sharing the oceanic nature, the geographic location, and the climatic regime. However, with specific characteristics according to the proximity of the islands to the mainland regions [6].

The archipelago of Madeira comprises the islands of Madeira (741 km2 of area), Porto Santo (42 km<sup>2</sup> ), Desertas (14 km<sup>2</sup> ), and the Selvagens islands (3 km2 ). The island of Madeira is located approximately at 635 km from Morocco and at 900 km from the Portuguese mainland. The Selvagens islands are the southernmost territory of Portugal at 239 km from the island of Madeira and at 375 km from the coast of Morocco. This subtropical archipelago is influenced by the Azores anticyclone, the Gulf and the Canary currents, the continental anticyclonic center of Northwest Africa and Western Europe, and the frontal systems associated with the lower pressure center of the polar front [7].

#### **Figure 1.**

*Representation of the southern part of the Northeastern Atlantic showing the study area, the archipelago of Madeira, included in the Macaronesian biogeographical region.*

The islands of Madeira and Desertas represent the most recent islands of the archipelago of Madeira with 4.6 and 3.6 million years, respectively. Porto Santo has an estimated age of 14.3 million years and the Selvages islands an estimated age between 24 and 29 million years [8, 9].

The population living in the archipelago of Madeira in 2017 was *ca.* 254 thousand inhabitants, and the fishing activity employed 618 registered fishermen (DRP-RAM). The annual landings increased 38.6% in relation to 2016 with 6.739 tonnes of fish and molluscs corresponding to 21,636 thousand €.

#### **2.1 Data collection**

Data on the landings (i.e., species, day, weight, and economic value) and on the artisanal fleet (i.e., length of the fishing vessel, tonnage, capacity, métier, fishery license) were obtained from the Regional Fisheries Department of Autonomous Region of Madeira (DRP-RAM) for both limpets and topshells.

Logbook data analyses were only available to characterize the limpet harvesting activity (i.e., harvesting area, typology of bottom, depth of harvesting, number of divers, number of snorkelers per vessel, and landing place and time), since it is mandatory to fill the logbooks according to the regulation of the limpet harvest in the archipelago of Madeira. For topshells these data are not available due to this activity not being regulated.

Landings data were compiled and analyzed covering the period from 1990 to 2017 and the logbook data from 2008 to 2017, concerning the period after the regulation of the harvesting of limpets that required the filling of all the harvesting information in logbooks.
