Incorporating spatial dynamics greatly increases estimates of long-term fishing effort: a participatory mapping approach

摘要

The location and intensity of small-scale fishing is dynamic over time, greatly shaping ecosystems. However, historical information about fishing effort and fishing gear-use are often unavailable. Within a marine biodiversity hotspot in the Philippines, we characterized spatio-temporal dynamics of fishing (1960-2010) using participatory mapping. First, we compared non-spatial and spatial estimates of total fishing effort. Our non-spatial estimate indicated that fishing increased 2.5 fold, reaching 1.3 million fishing days per year in 2010. Yet, spatial estimates showed fishing effort increased 20 fold, with the highest effort in 1990. Second, we evaluated how spatial characteristics of fishing changed over time. We introduced a method to estimate the sample size of fishers needed to accurately map the extent of fishing. By 2000, fishing extent grew 50% and small-scale fisheries affected over 90% of the coastal ocean. The expanded fishing area coincided with a greater spatial overlap among fishing gears and a proliferation of intensive fishing gears (destructive, active, non-selective). The expansion and intensification of fishing shown here emphasize the need for spatial approaches to management that focus on intensive, and often illegal, fishing gears. Such approaches are critical in targeting conservation actions (e.g. gear restrictions) in the most vulnerable areas.