Production, use and fate of Chilean brown seaweeds: re-sources for a sustainable fishery

Abstract

Chile is an important producer of brown seaweeds representing 10% of world supply. Landings of Chilean kelp fluctuated between 40,000 t.year −1 in the early '80s to 250,000 t.year −1 more recently. Commercialized algae come from natural populations and no mass-cultures of involved species have been established. Four species of brown algae are commercially collected in the country: Lessonia trabeculata, L. nigrescens, Macrocystis pyrifera and M. integrifolia. Since 2000, the demand of alginate sources and food for cultivated abalones dramatically raised the harvesting of these species. Direct evaluations of Lessonia spp. and Macrocystis standing-stocks were made along 700 km of coast in northern Chile. Lessonia spp. estimated populations exceed 900,000 t, whereas M. integrifolia does not exceed 300 t. The insights provided indicate that sustainability of Chilean kelp subjected to intense harvesting would require management programs including the following bio-ecological recommendations:(1) to harvest the entire plant including the holdfast; (2) to harvest plants larger than 20 cm in diameter; (3) to harvest plants sparsely, selecting mayor specimens; (4) rotation of harvesting areas; and (5) for Macrocystis, to cut the canopy 1-2 m from the surface. They must be implemented in a National Program of Kelp Management, elaborated by government, scientists, fisherman, and industry.

Effect of grazing on distribution and recovery of harvested stands of Lessonia berteroana kelp in northern Chile

“…In temperate habitats, kelp species are harvested through whole-plant or vegetative tissue removal (Tegner & Dayton 2000, Steneck et al 2002, 2013, Vásquez 2008. Along the Chilean coast, the dominant kelp species inhabiting intertidal habitats are Lessonia spp., which are heavily harvested by local fishermen who traditionally remove the whole plant from the substrate (see Fig.…”

“…(formerly L. nigrescens) were recently separated into 2 species: L. spicata, which is found between 42° and 30° S, and L. berteroana, which is distributed between 17° and 30° S and forms singlespecies stands (Tellier et al 2011, González et al 2012. Kelp fishery in Chile lands up to 300 000 dry tons annually and has an economic value exceeding US$70 million (Vásquez 2008). Harvesting of this ecologically relevant species is managed following a spatial rule that is based only on the spatial structure of mature kelp stands, but this spatial management approach does not consider the mechanisms underpinning the development of this spatial heterogeneity.…”

“…However, large intertidal benthic grazers like keyhole limpets and snails are targeted only by 'subsistence harvesters' (Castilla 1999), thus these species are not collected by 'kelp harvesters' in northern Chile (Vásquez 2008). Therefore, beyond the effect of grazers on natural communities of the kelp understory (i.e.…”

“…nearest neighbor inter-disc distances), which can affect the recovery of harvested kelp communities (Camus 1994, Rodríguez et al 2014). Since many human populations persist based exclusively on kelp harvesting (Vásquez 2008, this information is relevant to help improve management strategies and local policies.…”

Occurrence of arsenic species in the seagrass Posidonia oceanica and in the marine algae Lessonia nigrescens and Durvillaea antarctica

“…The two algae were selected since L. nigrescens and, especially, D. antarctica are healthy and nutritious edible seaweeds for humans and animals (Ortiz et al 2006) and are also used as a natural alginate source (Skjermo et al 2006;Vásquez 2008). It is reported that L. nigrescens has high sorption capacity of arsenic from the surrounding aquatic media, as is shown in samples collected in the Valparaiso Bay, Chile ).…”