When do marine reserves increase fishery yield?

Abstract

An age-structured model is developed for analyzing the effects of marine reserves and other long-term closures on fishery yield, assuming larvae are well-mixed and that exchange of adults between the open and closed areas is negligible. A number of analytic results are derived, including a formula for the gradient of yield with respect to fishing mortality and closure fraction. Increasing the closure fraction at equilibrium spawning stock biomass (SSB), B, will increase yield if and only if s′(B) > 1/b0(0), where s′(B) is the slope of the stock–recruitment curve at B and b0(0) is SSB per recruit at zero fishing mortality. Conditions for the level of closure required to prevent stock collapse are also derived. Applications of the theory to canary rockfish (Sebastes pinniger) and Georges Bank sea scallop (Placopecten magellanicus) illustrate that long-term closures increase yield only at low SSB associated with fishing mortalities greater than FMSY and with low closure fractions. The theory presented here gives simple analytic and graphical techniques for predicting the effects of long-term closures on yield and stock persistence.

Lessons on Marine Protected Area Management in Northern Boreal Regions from the United States and Norway

“…When both of these conditions are met, increased recruitment and reduced fi sh- ing mortality can result in a large increase in biomass inside the MPA. However, closures can increase fi shery yield only when the stock is recruitment overfi shed (Hart, 2006) Consistent with these ideas was the response of some of the fi sh stocks described in this paper. Sea scallop biomass in New England, lobster biomass in Norway, and sea peach abundance in the eastern Bering Sea increased inside the closures because they had been depleted and are not very mobile.…”

“…However, in order to increase yield, there needs to be suffi cient "spillover" of larvae and/or adults from the MPA into the fi shed areas that is greater than the direct loss of yield owing to the MPA (Hart, 2006), and insuffi cient spillover may not produce a net economic benefi t to the fi shery (Sanchirico et al, 2006;Gaines et al, 2010). Closing important fi shing grounds may lead to a spatial reallocation of effort into a smaller area as well as the loss of yield from fi sh that remain inside the MPA.…”

Optimal bioeconomic management of changing marine resources

“…2-6 (b)). Hart (2006) found a similar pattern in a single-species model, maximizing yield. The harvest rate that maximizes profit and the harvest rate at open access both increase.…”

The Relative Importance of the Sedge Island Marine Conservation Zone for Adult Blue Crabs in Barnegat Bay, New Jersey

“…MPAs have been established worldwide, and their effects on species assemblages and diversity (Barrett, Buxton, and Edgar, 2009;Bell, 1983;Holland and Schnier, 2006;Lipej, Bonaca, and Sisko, 2003), fisheries productivity (Alcala et al, 2005;Gell and Roberts, 2003;Goni, Quetglas, and Renones, 2006;Hart, 2006;Roberts et al, 2001), and population characteristics of a variety of fish (Le Port, Lavery, and Montgomery, 2012;Macpherson, Garcia-Rubies, and Gordoa, 2000) and invertebrates (Barrett, Buxton, and Edgar, 2009;Branch, and Odendaal, 2003;Jack and Wing, 2010;Leite et al, 2009) have been well studied. Although the positive effects of MPAs are not universal (Edgar et al, 2014), the benefits of MPAs to individual species as a result of reduced fishing effort include increased abundance (Curley et al, 2013;Golbuu and Friedlander, 2011;Jack and Wing, 2010;Moland et al, 2013) and body size (BeukersStewart et al, 2005;Bevacqua et al, 2010;Branch and Odendaal, 2003;Pillans et al, 2005), particularly of reproducing adults, suggesting MPAs can enhance the reproductive capacity of species they protect (Kaiser et al, 2007).…”