Abesamis et al How much does the fishery at Apo Island benefit from spillover from a marine reserve' 



361 



Marine Park are rare. In the Philippines, for example, 

 reserves that are created with fishery enhancement 

 as a major goal are typically small (<1 km- of reef 

 area) and occupy £25% of the available local fishing 

 area (Alino et al., 2002). To date, only two studies of 

 Philippine reserves, Sumilon and Apo (-25% and -10% 

 respectively of fishing area are no-take reserves), have 

 shown persuasively that spillover yield may affect to- 

 tal fishery yield (Alcala and Russ, 1990; Russ et al., 

 2004, Alcala et al., 2005). In both cases, however, the 

 magnitude of actual spillover yield was unclear (Russ 

 et al., 2004, Alcala et al., 2005). On the other hand, 

 two studies, one in St. Lucia (Roberts et al., 2001) and 

 one in Egypt (Galal et al., 2002), demonstrated that 

 catch rates of fishermen increased several years after 

 the creation of networks of reserves. It was argued in 

 these studies that the reserves increased total fishery 

 yield because catch rates improved but fishing effort 

 remained constant. However, these studies provided no 

 information on total fishery yield, precluding estimation 

 of the magnitude of spillover benefits. More empirical 

 studies are needed to provide assessment of potential 

 spillover effects on adjacent fisheries. 



Besides available fishing area, the total fishery yield 

 for a given location will be determined by fishing in- 

 tensity (Hilborn and Walters, 1992). In addition, theo- 

 retical studies indicate that spillover yield will be a 

 function of reserve size, fishing mortality rate, and 

 demographic parameters of target species, particularly 

 movement rates (Polacheck, 1990; Russ et al. 1992; 

 DeMartini, 1993). However, the actual contribution 

 of spillover to total yield will be determined by fish- 

 ing intensity adjacent to reserves. Indeed it has been 

 suggested that the "first" sign of spillover is the sight 

 of fishermen fishing close to reserve boundaries (Gell 

 and Roberts, 2003). This phenomenon would occur pre- 

 sumably in response to higher catch rates near than 

 far from reserves. Spillover is predicted to produce a 

 pattern of higher abundance of target species outside 

 but close to reserve boundaries, but lower abundance 

 farther away (Rakitin and Kramer, 1996; Kramer and 

 Chapman, 1999). Decreasing catch rates (an index of 

 abundance) away from reserve boundaries have been 

 demonstrated by experimental trap fishing outside one 

 reserve in Barbados and one reserve in Kenya (Rakitin 

 and Kramer, 1996; McClanahan and Mangi, 2000). 

 Also, monitoring studies of reserves in Kenya and the 

 Philippines have shown that catch rates of fishermen 

 were higher closer to reserve boundaries than farther 

 away (McClanahan and Kaunda-Arara, 1996; McClana- 

 han and Mangi, 2000; Russ et al., 2003, 2004). In New 

 Zealand, large catches of lobsters were found to be more 

 common closer to Leigh Marine Reserve than farther 

 away (Kelly et al., 2002). However, it is less clear if 

 fishermen tend to concentrate more effort adjacent to 

 reserves when spillover may be present. Some studies 

 suggest that fishermen may do so (McClanahan and 

 Kaunda-Arara. 1996; McClanahan and Mangi, 2000), 

 whereas other studies indicate that fishermen do not 

 (Russ et al., 2003; Wilcox and Pomeroy, 2003). Some of 



the evidence for fishermen preferentially fishing near 

 reserves is anecdotal (Gell and Roberts^. Nevertheless, 

 it is important to stress that intense fishing near the 

 reserve may have the effect of eventually reducing catch 

 rates there (McClanahan and Mangi, 2000). 



Fishing effort may not necessarily track the spa- 

 tial distribution of fish abundance. Fishermen may not 

 favor fishing adjacent to reserves even if catch rates 

 there are higher. Catch rates alone may not explain 

 the spatial distribution of fishing effort, because deci- 

 sions by fishermen on where to fish are usually aimed 

 at making a profit. Hence, decisions may be influenced 

 by fishing costs, such as fuel or time used traveling to 

 fishing areas (Hilborn and Walters, 1992). These costs 

 will be related to the distance of fishing grounds from 

 home ports or residences of fishermen (e.g., Wilcox and 

 Pomeroy, 2003). If such costs are negligible, then fish- 

 ing effort may reflect the spatial pattern of catch rates, 

 provided that fishermen have ample information on 

 the latter. However, this situation may be unlikely if 

 fishermen keep information about productive areas to 

 themselves. Furthermore, the strategies of fishermen 

 may become highly complex in fisheries that employ 

 a variety of fishing gears and target a multitude of 

 species (Hilborn and Walters, 1992). This is likely to 

 be particularly true of coral reef fisheries in develop- 

 ing countries (Munro, 1996). Spatial distribution of 

 fishing effort in such fisheries may also depend upon 

 the differential value of target species. In addition, 

 other factors that are unrelated to income may also 

 influence the spatial pattern of fishing effort. These 

 include weather conditions and social factors, such as 

 local traditions or agreements among stakeholders and 

 managers (Wilcox and Pomeroy, 2003). Consideration of 

 the behavior of fishermen in relation to reserves may 

 help determine if reserves are achieving their goal of 

 improving fishery yields through spillover. Successful 

 use of reserves to enhance fisheries would require a 

 case by case understanding of the spatial structure of 

 impacted fisheries, ecosystems, and human communities 

 (Hilborn et al., 2004). 



The objective of this study was to estimate the upper 

 limit of the spillover contribution of the no-take reserve 

 at Apo Island, Philippines to the local fishery yield. 

 The reserve at Apo Island has been protected for over 

 20 years (since 1982), and there is evidence to suggest 

 that spillover is present (Russ and Alcala, 1996; Russ et 

 al., 2003, 2004; Alcala et al., 2005). However, previous 

 studies indicate that access by fishermen to productive 

 areas far from the reserve during favorable weather 

 influences the local fishery yield considerably (White 

 and Savina, 1987; Bellwood, 1988). In the present study, 

 daily fishing effort and yield were documented for eight 

 months covering two monsoonal seasons. Spatial and 

 temporal patterns of fishing effort, yield (biomass and 

 value), and catch rates were examined among fishing 



1 Gell, F., and C. M. Roberts. 2002. Unpubl. report. The 

 fishery effects of marine reserves and fishery closures, 89 p. 

 WWF-US, 1250 24'h Street. NW, Washington D.C. 20037. 



