Cost‐Effectiveness of Alternative Conservation Strategies with Application to the Pacific Leatherback Turtle

Abstract

Although holistic conservation addressing all sources of mortality for endangered species or stocks is the preferred conservation strategy, limited budgets require a criterion to prioritize conservation investments. We compared the cost-effectiveness of nesting site and at-sea conservation strategies for Pacific leatherback turtles (Dermochelys coriacea). We sought to determine which conservation strategy or mix of strategies would produce the largest increase in population growth rate per dollar. Alternative strategies included protection of nesters and their eggs at nesting beaches in Indonesia, gear changes, effort restrictions, and caps on turtle takes in the Hawaiian (U.S.A.) longline swordfish fishery, and temporal and area closures in the California (U.S.A.) drift gill net fishery. We used a population model with a biological metric to measure the effects of conservation alternatives. We normalized all effects by cost to prioritize those strategies with the greatest biological effect relative to its economic cost. We used Monte Carlo simulation to address uncertainty in the main variables and to calculate probability distributions for cost-effectiveness measures. Nesting beach protection was the most cost-effective means of achieving increases in leatherback populations. This result creates the possibility of noncompensatory bycatch mitigation, where high-bycatch fisheries invest in protecting nesting beaches. An example of this practice is U.S. processors of longline tuna and California drift gill net fishers that tax themselves to finance low-cost nesting site protection. Under certain conditions, fisheries interventions, such as technologies that reduce leatherback bycatch without substantially decreasing target species catch, can be cost-effective. Reducing bycatch in coastal areas where bycatch is high, particularly adjacent to nesting beaches, may be cost-effective, particularly, if fisheries in the area are small and of little commercial value.

Fisheries bycatch reduction within the least-cost biodiversity mitigation hierarchy: Conservatory offsets with an application to sea turtles

“…Incentive-based policy instruments, which price bycatch, are increasingly used to avoid and minimize bycatch and restore bycatch stocks in a least-cost way [5,7,8,13,15,16,17,19,20].…”

“…Their costs, and hence prices, will correspondingly differ, since they form under different circumstances and objectives. 6 A tax could incentivize changes in producer and consumer behavior and the proceeds finance costs of conservatory offsets [5,7,8,11,17,19,20,23]. The tax is ideally levied on bycatch mortality (i.e.…”

“…First, the Hawaii shallow-set pelagic longline swordfish fishery has a bycatch of Pacific loggerhead and leatherback sea turtles [8].…”

“…Endangered 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 14 management program TurtleWatch, that is on-stock, in-kind, essentially on-site, to avoid sea turtle "hot spots" [10]. the California drift gillnet fishery, even allowing for risk [8]. Conservatory offsets, through nesting site conservation, would therefore provide least-cost bycatch mitigation, and provide an alternative incentive-based policy instrument to help reduce costs of avoidance (e.g.…”

“…8 Conservatory offsets, on the contrary, can be adjusted as stock abundance, environment, markets, and technology change. They might result in No Net Loss or even Net Gain in the adult impacted population depending on the amount of reproduction enhancement achieved.…”