Unravelling Lessonia trabeculata management in coastal areas of the Atacama region of northern Chile through a DPSIR approach: Insights for sustainable plans

Abstract

Subtidal Lessonia trabeculata is one of the primary kelp resources of northern Chile. It is an ecosystem engineer that provides habitat, shelter, and food for invertebrates and fish. This fishery has been developed by a collection of stranded algae carried out by legally registered fishers and illegal collectors in open-access areas and management and exploitation areas for benthic resources. Due to the current high demand on the international market, the collection of dead plants is supplemented by direct extraction. In response, a management plan has been implemented to regulate extraction efforts and institute annual quotas. The dynamics of the L. trabeculata fishery in the Atacama region over 20 years were evaluated using the conceptual framework of the driver-pressure-state-impact-response (DPSIR) approach. The fishing dynamics are strongly conditioned by price fluctuations, promoting the growth of fishing efforts (pressure) in response to economic indicators (driving forces). This often leads to a high volume of extractions of resources (impact) reflected in the increase in extractors and landings in spite of the establishment of quotas (responses), that generate intense pressure on local populations of algae and other commercially important fish and invertebrates (state). A lack of knowledge was detected regarding population aspects and its associated communities. Consequently, this kelp has been mismanaged without a specific focus on this species. Finally, the indicators included in the present DPSIR analysis enable a global understanding of the L. trabeculata fishery, and it should be considered as a basis for future studies and the implementation of resource management strategies.

Introduction

The brown macroalgae Lessonia trabeculata inhabits the rocky subtidal zone (up to 40 m deep) of the Pacific coast of South America, from the south of the Peruvian to Chilean coast [1]. This kelp is the most abundant brown macroalgae in subtidal environments throughout much of the Chilean coast (18–42°S) [2], [3]. L. trabeculata supports essential ecological assemblages, forming habitats [4], [5], [6], [7] and providing services and ecosystem functions, such as food sources and shelters for different species of invertebrates and fish [8], [9], [12] and a reduction of wave intensity and water flow [13], [14].

L. trabeculata is a resource of great economic importance for the artisanal fishing sector of the country, with landings that exceed 18,000 tonnes per year [15] and social contributions with a direct workforce of more than 4000 fishers in the last decade [16]. Its exploitation began in the 1980s with the collection of stranded L. trabeculata algae [2]. The most significant interest in Lessonia spp. resources coincided with the collapse of many benthic fisheries, prompting many fishers to become collectors and extractors of brown algae [3], [17]. In the last 20 years, the landing of this brown algae has shown a substantial historical maximum first in 2013 and later in 2017 due to the growing demand for alginates from the international market in countries such as China, Japan, Norway, and France [16]. Additionally, the abalone industry requires L. trabeculata for aquaculture feeding [18].

The contribution to kelp landings on the coast of the Atacama region is one the most important for Chilean production (2017–2018), constituting 32% of the total; the annual landing of L. trabeculata is approximately 25,000 tonnes. At the Atacama regional level, the fishery generates 97,748 USD and 4000 jobs for the artisanal fishing sector [16]. This fishery presents problems, such as the rapid filling of annual harvest quotas, contending with illegal extraction activities, and the use of indiscriminate extraction techniques [16]. These aspects hamper management plans and governance.

By 2005, the increase in resource value propelled the change from dead algae collection due to landing (natural mortality) to direct extraction [3], [18]. Direct harvesting by means of detaching algae from the rocky substrate using crowbars negatively affects the density, size, and morphology of algae, changing biological communities into predominantly barren ground [19], [20]. In this current scenario of a notable increase in the extractive pressure on kelp, the Undersecretary of Fisheries and Aquaculture (SUBPESCA) developed a programme to regulate fishing and research that has been implemented since 2005. The programme is based on the biological and fishing regulations that are part of management plans to guarantee the sustainability of kelp resources as measured by biological aspects: minimum extraction sizes, appropriate removal methods, extractive closures, and annual quotas [18]. Additionally, extra measures have been suggested, such as area rotation; the intercropping of plants; the repopulation, restoration, or creation of new management areas [3], [21], [22], [23], [24], [25]; and the establishment of marine reserves to foster kelp protection. All of these specific management strategies aim to regulate landing and promote sustainable exploitation.

The commercial exploitation of L. trabeculata is closely linked to the fisheries activity of the Lessonia nigrescens complex. They share aspects such as extraction agents and the methods of extraction and mincing. However, the same amount of information about the population and community aspects of L. trabeculata are not available, which requires specific management measures [26]. The sustainable development for wild L. trabeculata fisheries requires an understanding of the population dynamics and the ecosystems that they support. Therefore, it is necessary to design and develop a conceptual framework for a sustainable management programme that incorporates the dynamic complexity of the dimensions of the ecological-economic-social system related to this type of fishery [27], [28].

In this context, an analysis based on an integrated management framework [30], [31] is required to identify and unravel the different factors that govern the sustainability of the fisheries of L. trabeculata. The purpose is to evaluate the economic, social, and ecological conflicts in its fishery derived from the implementation of a single general brown algae management programme in northern Chile. One of the tools available and developed by the OECD (Organisation for Economic Cooperation and Development, 1993) and EEA (European Environment Agency, 1995) is the driver-pressure-state-impact-response (DPSIR) conceptual framework. DPSIR is a simple tool for contextualising major environmental issues, contributing to the decision-making process and regulatory enforcement. It also facilitates the inclusion of modules linked to anthropic activities, appropriately distributing the systems analysed, and selecting the relevant indicators for their functioning [42]. This conceptual framework is particularly relevant for assessing the status of the L. trabeculata alga fishery in northern Chile. In order to better understand the past and current problems related to fishery sustainability (e.g., overexploitation and price speculation) [32], [33], [34], [35], [36], [37], it allows us to identify cause-effect relationships among the selected indicators in drivers, pressures, state, impact and response [29] and facilitates communication channels among users, scientists, and decision-makers, among others [33].

This study evaluated the management of an L. trabeculata fishery by using the DPSIR conceptual framework. The main goals were to (i) identify and classify the principal indicators (socioeconomic, ecological, and administrative) affecting the performance of this fishery; (ii) chronologically review the management measures (legal, management, and operational) established for fishing regulations; and (iii) propose considerations for future management plans based on current gaps identified by DPSIR analysis.