Limits...
Marine reserve effects on fishery profit.

White C, Kendall BE, Gaines S, Siegel DA, Costello C - Ecol. Lett. (2008)

Bottom Line: We incorporated this effect into a bioeconomic model to evaluate the economic performance of reserve-based management.Our results indicate that reserves can still benefit fisheries, even those targeting species that are expensive to harvest.Furthermore, reserve area and harvest intensity can be traded off with little impact on profits, allowing for management flexibility while still providing higher profit than attainable under conventional management.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA.

ABSTRACT
Some studies suggest that fishery yields can be higher with reserves than under conventional management. However, the economic performance of fisheries depends on economic profit, not fish yield. The predictions of higher yields with reserves rely on intensive fishing pressures between reserves; the exorbitant costs of harvesting low-density populations erode profits. We incorporated this effect into a bioeconomic model to evaluate the economic performance of reserve-based management. Our results indicate that reserves can still benefit fisheries, even those targeting species that are expensive to harvest. However, in contrast to studies focused on yield, only a moderate proportion of the coast in reserves (with moderate harvest pressures outside reserves) is required to maximize profit. Furthermore, reserve area and harvest intensity can be traded off with little impact on profits, allowing for management flexibility while still providing higher profit than attainable under conventional management.

Show MeSH
Yield and profit in relation to the stock effect, proportion of the coast in reserves and escapement in fished areas. (a–e) Yields and profits under different stock effect scenarios, given optimal configuration of reserves compromising a proportion of the coast (‘% Reserves’, where zero represents conventional management). Curved lines represent different escapement levels regulated across the fished region. For reference, the horizontal dashed lines indicate maximum yield and profits attainable under optimal conventional management. M = 0.1, P = 1, results are quantitatively identical across all evaluated mean larval dispersal distances. (f) Optimal per cent reserve and escapement policies that maximize yield (θ = 0, squares) and profit (θ > 0, circles), for all combinations of M, P and θ values in Table 1. In general, optimal management was characterized by decreased per cent reserves concurrent with increased escapement as θ increased (arrow). Symbol size corresponds with policy frequency. Conventional management (upper left points) was optimal when P = 1 and θ = 20 [e.g. panel (e)], in all of those cases, sub-optimal management with up to 35% reserves only decreased profits by < 5%.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2268951&req=5

fig02: Yield and profit in relation to the stock effect, proportion of the coast in reserves and escapement in fished areas. (a–e) Yields and profits under different stock effect scenarios, given optimal configuration of reserves compromising a proportion of the coast (‘% Reserves’, where zero represents conventional management). Curved lines represent different escapement levels regulated across the fished region. For reference, the horizontal dashed lines indicate maximum yield and profits attainable under optimal conventional management. M = 0.1, P = 1, results are quantitatively identical across all evaluated mean larval dispersal distances. (f) Optimal per cent reserve and escapement policies that maximize yield (θ = 0, squares) and profit (θ > 0, circles), for all combinations of M, P and θ values in Table 1. In general, optimal management was characterized by decreased per cent reserves concurrent with increased escapement as θ increased (arrow). Symbol size corresponds with policy frequency. Conventional management (upper left points) was optimal when P = 1 and θ = 20 [e.g. panel (e)], in all of those cases, sub-optimal management with up to 35% reserves only decreased profits by < 5%.

Mentions: Given our baseline life history parameters, yield under conventional management was maximized by setting escapement to 34% of virgin carrying capacity (Fig. 2a, horizontal dashed line). Maximum yields with reserves were substantially greater, but required high harvest pressure (escapement < 30%) between optimally configured reserves that constituted a large fraction (20–60%) of the coastline (Fig. 2a, curved lines). The overall maximum yield emerged when reserves constituted 60% of the coast and escapement outside them was zero. The only effect of dispersal distance was to change the ‘optimal configuration’ at each reserve proportion.


Marine reserve effects on fishery profit.

White C, Kendall BE, Gaines S, Siegel DA, Costello C - Ecol. Lett. (2008)

Yield and profit in relation to the stock effect, proportion of the coast in reserves and escapement in fished areas. (a–e) Yields and profits under different stock effect scenarios, given optimal configuration of reserves compromising a proportion of the coast (‘% Reserves’, where zero represents conventional management). Curved lines represent different escapement levels regulated across the fished region. For reference, the horizontal dashed lines indicate maximum yield and profits attainable under optimal conventional management. M = 0.1, P = 1, results are quantitatively identical across all evaluated mean larval dispersal distances. (f) Optimal per cent reserve and escapement policies that maximize yield (θ = 0, squares) and profit (θ > 0, circles), for all combinations of M, P and θ values in Table 1. In general, optimal management was characterized by decreased per cent reserves concurrent with increased escapement as θ increased (arrow). Symbol size corresponds with policy frequency. Conventional management (upper left points) was optimal when P = 1 and θ = 20 [e.g. panel (e)], in all of those cases, sub-optimal management with up to 35% reserves only decreased profits by < 5%.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2268951&req=5

fig02: Yield and profit in relation to the stock effect, proportion of the coast in reserves and escapement in fished areas. (a–e) Yields and profits under different stock effect scenarios, given optimal configuration of reserves compromising a proportion of the coast (‘% Reserves’, where zero represents conventional management). Curved lines represent different escapement levels regulated across the fished region. For reference, the horizontal dashed lines indicate maximum yield and profits attainable under optimal conventional management. M = 0.1, P = 1, results are quantitatively identical across all evaluated mean larval dispersal distances. (f) Optimal per cent reserve and escapement policies that maximize yield (θ = 0, squares) and profit (θ > 0, circles), for all combinations of M, P and θ values in Table 1. In general, optimal management was characterized by decreased per cent reserves concurrent with increased escapement as θ increased (arrow). Symbol size corresponds with policy frequency. Conventional management (upper left points) was optimal when P = 1 and θ = 20 [e.g. panel (e)], in all of those cases, sub-optimal management with up to 35% reserves only decreased profits by < 5%.
Mentions: Given our baseline life history parameters, yield under conventional management was maximized by setting escapement to 34% of virgin carrying capacity (Fig. 2a, horizontal dashed line). Maximum yields with reserves were substantially greater, but required high harvest pressure (escapement < 30%) between optimally configured reserves that constituted a large fraction (20–60%) of the coastline (Fig. 2a, curved lines). The overall maximum yield emerged when reserves constituted 60% of the coast and escapement outside them was zero. The only effect of dispersal distance was to change the ‘optimal configuration’ at each reserve proportion.

Bottom Line: We incorporated this effect into a bioeconomic model to evaluate the economic performance of reserve-based management.Our results indicate that reserves can still benefit fisheries, even those targeting species that are expensive to harvest.Furthermore, reserve area and harvest intensity can be traded off with little impact on profits, allowing for management flexibility while still providing higher profit than attainable under conventional management.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA.

ABSTRACT
Some studies suggest that fishery yields can be higher with reserves than under conventional management. However, the economic performance of fisheries depends on economic profit, not fish yield. The predictions of higher yields with reserves rely on intensive fishing pressures between reserves; the exorbitant costs of harvesting low-density populations erode profits. We incorporated this effect into a bioeconomic model to evaluate the economic performance of reserve-based management. Our results indicate that reserves can still benefit fisheries, even those targeting species that are expensive to harvest. However, in contrast to studies focused on yield, only a moderate proportion of the coast in reserves (with moderate harvest pressures outside reserves) is required to maximize profit. Furthermore, reserve area and harvest intensity can be traded off with little impact on profits, allowing for management flexibility while still providing higher profit than attainable under conventional management.

Show MeSH