Effort distribution and catch patterns adjacent to temperate MPAs

Abstract

We evaluated the spatial distribution of otter trawl fishing effort and catches resulting from the imposition in 1994 of year-round and seasonal groundfish closed areas off the NE USA. Vessel locations were available from logbooks, vessel monitoring system (VMS) data from many of the largest vessels, and from observer records. There was high spatial coherence between VMS-and observer-derived trawling locations. Prior to establishment, 31% of trawl effort (1991e1993) occurred within the 22 000 km 2 of area that would eventually be closed year-round. In 2001e2003 about 10% of effort targeting groundfish was deployed within 1 km of the marine protected area (MPA) boundaries, and about 25% within 5 km. Density gradients, consistent with spill-over from MPAs, were apparent for some species. Average revenue per hour trawled was about twice as high within 4 km of the boundary, than for more distant catches, but the catch variability was greater nearer closed area boundaries. Seasonal closed areas attracted more fishing effort after opening than prior to closure even while average cpue was the same or lower. Spatial resolution of traditional data sources (e.g., logbooks) was too crude to discern detailed MPA-related effects, as revealed by high-resolution vessel positions from VMS and catch data obtained by observers.

Spillover from marine reserves and the replenishment of fished stocks

“…Our estimates of spillover distance are consistent with studies of large-scale partial-protection marine protected areas that find even greater spillover distances (Murawski et al 2005), with studies of adult movement patterns showing similar or greater distances of movement across reserve boundaries (for example (Samoilys 1997;Kelly & MacDiarmid 2003;Topping et al 2005), and with estimates from spillover studies that did not meet our inclusion criteria (Abesamis & Russ 2005;Goni et al 2008;Harmelin-Vivien et al 2008;Williams et al 2009). However, in all of these cases, spillover acts at relatively small scales such that single reserves cannot sustain entire fished stocks (through spillover alone; they may be able to provide this service through larval export).…”

“…Spillover may also take time to accrue, exacting short-term costs on fishers (Smith & Wilen 2003). However, studies that have focused on catch metrics (effort and value) support our finding that spillover can compensate fishers (Roberts et al 2001;Murawski et al 2005). Furthermore, our assumption that fishing effort remains constant when redistributed over the entire sampled area when the reserve is hypothetically removed may not be realistic, and influences our estimates of the sustainability of the fishery without the reserve.…”

Effects of habitat on spillover from marine protected areas to artisanal fisheries

“…Some of the best evidence for spillover comes from landings data that have demonstrated increased captures in fisheries adjacent to MPAs in many parts of the world: Kenya (McClanahan & Kaunda-Arara 1996, McClanahan & Mangi 2000, Florida and St Lucia (Roberts et al 2001a), New England (Murawski et al 2000(Murawski et al , 2005, the Egyptian Red Sea (Galal et al 2002) and Apo Island in the Philippines (Russ et al 2003). However, only a few studies have experimentally tested for spillover through increased captures in adjacent fished areas, often along density gradients: Barbados (Rakitin & Kramer 1996), Kenya (McClanahan & Mangi 2000, Kaunda-Arara & Rose 2004 and Apo Island in the Philippines (Abesamis & Russ 2005).…”

Evaluating the effect of fishery closures: Lessons learnt from the Plaice Box

“…Atlantic, where large areas have been closed to fishing to protect depleted groundfish stocks and most, but not all, groundfish stocks recovered (Murawski et al, 2005). Recoveries in benthos and benthic habitats were also observed (Hermsen et al, 2003;Lindholm et al, 2004;Asch et al, 2008).…”