The community structuring by subtidal kelpbeds and its importance for artisanal fisheries in northern Chile


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Juergen.Laudien [ at ] awi.de

Abstract

The coastal (artisanal) fisheries of northern Chile center principally on littoral resources of the rocky shore. Data for landings of Lessonia nigrescens/trabeculata, Thais chocolate, Concholepas concholepas, Aulacomya ater, Octopus mimus, Fisurella spp., Cancer setosus/polyodon/porteri and Loxechinus albus in Chile/Peru and northern Chile were presented by Thatje et al (2007). Quantitative and reliable data for fish landings are available for Medialuna ansietae, Semicosyphus darwini and Paralabrax humeralis. Data for other species (Syciases sanguineus, Graus nigra, Oplegnathus insignis, Labriosomus philippii, Hemilutjanus macropthalmus, Pinguipes chilensis, Cheilodactylus variegates) are not reliable because of lack of control and extensive landing registers. The management concept (excedentes productivos, monospecific management programs) of the Chilean fisheries (see: Ley General de Pesca y Acuicultura), the missing of minimum capture size, quote regulations for most part of the rock fishes, lack of inforcements in the control of management of the existing areas de manejo, need of effective regulations for the development of new management areas, lack or insufficient control of fishing outside of management areas is leading to overexploitation of many coastal invertebrate resources (see: Castilla & Fernández 1998, Fernández 2005 for Concholepas concholepas) and fishes (see: Sielfeld et al. 2002), Villegas et al (2007) for Medialuna ansietae, Semicosiphus darwini, Oplegnathus insignis, Hemilutjanus macropthalmus) and may put their sustainable management in risk. Most part of these resources inhabit kelp habitats (dominated by Lessonia trabeculata Villouta and Santelices 1986 and Macrocystis integrifolia Bory 1826) taking advantage of the shelter provided by the habitat structure and availability of food (Nuñez & Vásquez 1987, Godoy 2000, Angel & Ojeda 2001, Aguirre 2004). The abundance and distribution of the macrobenthic community between holdfasts of these kelp beds were previously described by Villegas et al (2008) and revealed differences in the morphology of both types of kelp beds, differences in the composition of their characteristic fauna and the interactions between the invertebrate components. The invertebrate fauna of holdfasts, stipes and fronds of 36 sporophytes from bahía Chipana (see: Trigo, Villegas & Sielfeld, not published data) showed 47 invertebrates, most abundant in association to L. trabeculata and composed of Annelida (5 sp, 10,6%), Brachiopoda (1 sp, 2,1%), Briozoa (1 sp, 2,1%), Mollusca (21 sp, 44,7%) Crustacea (14 sp, 29,8%), Echinodermata (4 sp, 8,5%) and Urochordata (1 sp, 2,1%). Abundances indicate Annelida Sabellariidae (as most abundant in L. trabeculata from belts and from barren ground situations (4,52 + 8,30 and 6,38+7,91), Cnidaria sp.indet. and Mytilidae Aulacomya ater in L. trabeculata from barren ground situations (4,61+ 6,91 and 54,88+93,68), Gammaridae sp. indet. on Macrocystis integrifolia (7,1+11,21). Mytilidae Brachidontes granulata, Choromytilus chorus, Semimitylus algosus were most abundant on Lessonia trabeculata of the belts (23,11+73,89; 35,75+205,98; 50,13+114,77). Overlap between the species assemblage associated to holdfasts and fronds and the macroinvertebrate assemblage between plants is low and comprises principally mobile species (Echinodermata: Tetrapygus niger, Loxechinus albus; Mollusca: Fisurella maxima, Concholepas concholepas, Crassilabrum crassilabrum, Aulacomya ater). The kelp habitats are inhabited by a diverse fish community composed of species that use shelter and food availability of a three-dimensional habitat structure (Nuñez & Vásquez 1987, Vargas et al. 1999, Godoy 2000, Angel & Ojeda 2001, Pérez & Matus 2007, Villegas et al in lit). Trophic relations of these species in northern Chile were described by Vasquez (1993), Vargas et al (1999), Berrios & Vargas (2004) and show& Sielfeld 2008). Kelp communities comprise complex food webs and energy pathway scenarios (Graham 2004, Graham et al 2007). If disturbance of the habitat structure will modify the trophic relationships of the invertebrate and fish assemblages in the different kelp habitats, affecting the diversity and productivity of the system (Graham op cit.) and trophic dynamics (Villegas et al 200.. ), than natural changes (ENSO) or antropogenic impacts (overfishing of particular species, collecting of target species inside the management areas but collected outside these areas) will affect the ecological sustainability of the kelp community and the economic stability of the local fishermen community. On the base of a conceptual food web model for kelp, invertebrates and fishes from Bahía Chipana, species interrelations are discussed. It is concluded that the sustainable management of the chilean parcelas de manejo, the socioeconomic stability of the fishermen and the coastal ecosystem management/restoration is not possible with the actual monospecific management programs and must be changed by a more complete multispecific management program.



Item Type
Conference (Talk)
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
CENSOR Endterm Symposium, 9-11 September 2008, Lima, Peru...
Eprint ID
19613
Cite as
Sielfeld, W. , Villegas, M. , Laudien, J. and Arntz, W. (2008): The community structuring by subtidal kelpbeds and its importance for artisanal fisheries in northern Chile , CENSOR Endterm Symposium, 9-11 September 2008, Lima, Peru.. .


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