No abstract

La pesca artesanal multiespecífica en la cuenca del Magdalena involucra a más de 30.000 pescadores. La gestión clásica identifica a la sobrepesca como la responsable del agotamiento de los peces y como el factor primordial a controlar. Así, la pesca selectiva (tallas de peces y tamaño de ojos de malla) se plantea como la forma de reducir los efectos que esta genera en los ecosistemas y a su vez aumentar los rendimientos pesqueros. No obstante, hallazgos recientes desafían esta narrativa sugiriendo que el patrón de explotación de los pescadores a pequeña escala podría estar más cerca de un enfoque ecosistémico. Para analizar este planteamiento se realizó un análisis del efecto de las presiones que ejerce la pesca artesanal sobre las comunidades de peces y el ecosistema, soportada en la identificación de los cambios en la producción pesquera, en la estructura trófica y en los tamaños de las especies, junto con las modificaciones en la biomasa relativa, composición, biomasa óptima, tasa de explotación y artes de pesca. Al final se contempla la posible respuesta de los pescadores hacia una autorregulación, concluyendo que la gestión clásica ha generado efectos contrarios a lo deseado. En consecuencia, como contribución a los administradores de la pesca, se presentan recomendaciones dirigidas a modificar los paradigmas de manejo actuales y se reafirma la necesidad de fortalecer los procesos de gobernanza.

24Overfishing has been historically considered as the main cause of fish stock 25 depletion worldwide. This paradigm has oriented fishery management towards a 26 classical approach, under which externalities to fisheries were not considered as they 27 were difficult to assess and measure. The aim of this study is to describe the dynamics 28 of different environmental, economic, and demographic variables (water flow, forest 29 cover, gold production, population growth, stored water volume, and sediments) in 30 relation to the behavior of the fishery production in the Magdalena-Cauca river basin 31 from 1980 to 2015. Generalized Additive Models were used to determine the variables 32 that best explain fishery production. The findings confirmed that environmental 33 deterioration of the Magdalena River basin explained at least 60% of the reduction in 34 fishery production. Thus, we concluded that the traditional approach of making fishers 35 responsible for the decline of fish production was a misguided argument, and before 36 implementing restrictions on fishing activity, a better understanding of the overall 37 system is crucial. Hence, fishery management should involve the economic and social 38 sectors that affect the offer of ecosystem services within the basin, including fishing. 40 Introduction 41Historically, overfishing was considered to be the main cause of fish stocks 42 depletion in the world. This fact guided fisheries management towards a classical 43 approach that did not adequately consider the impacts of external factors, either because 44 they were difficult to control (1,2), or complex to characterize. This is the case in inland 45 fisheries, being rivers the most impacted ecosystems by human activities over the past 46 100 years. Furthermore, many activities linked to the use of natural resources that imply 3 47 intense human interventions take place in rives, threatening their functionality (flow 48 rates disruption, erosion, alterations of habitats, among others) (3). As a consequence, it 49 is imperative to study the anthropic effects on both, the environment as well as on 50 natural fish populations, before ascribing all impacts to fishing activity (4). Therefore, 51 as fisheries cannot be considered isolated, a multifactorial approach is required for their 52 assessment and management (5). 54According to the abovementioned, inaccurate or incomplete diagnoses of the 55 root causes of overfishing can lead to errors in the formulation and implementation of 56 fishing policies or programs (6). This phenomenon responds to a lack of knowledge on 57 the impacts of other sectors (i.e., agriculture, mining, and transport, among others) in 58 inland fisheries, which together with a northern hemisphere industrial fisheries approach 59 (1) have resulted in the overall reduction of fishery resources. Moreover, these concepts 60 are focused on internal factors such as size, fishing gear, reproductive seasons, and 61 reserve areas, aimed to achieve sustainability only through their management (1,7). 62 63 ...