ИСТИНА |
Войти в систему Регистрация |
|
ИПМех РАН |
||
This modeling project was inspired by policy issues that arise in the Western and Central Pacific Fisheries Management Commission. The methods are both conceptual and empirical, and are relevant to management of highly migratory marine fish-stocks worldwide. Harvesting may occur throughout the fish stock’s range, including in EEZs of coastal-nations. It is carried out by national fleets of a second set of nations, some geographically distant from the range. Overall management of the fishery is the joint responsibility of these two (overlapping) classes of stake-holding nations. They act through the agency of a Regional Fishery Management Organization (RFMO), with members the nations in these two stake-holding classes. The RFMO is a political organization, with regulatory powers delegated by the member countries. Its governing Commission, whose members represent the RFMO countries, sets seasonal harvesting regulations which are intended to protect both current profitability and future sustainability of the fishery. The Commission’s basic decision is to partition the current “recruitment” of harvestable stock into the current season’s allowable catch and its season-end “escapement”, which constitutes the brood stock for the subsequent season’s recruitment. These annual allocations, between current profitability and future sustainability, are negotiated within the RFMO Commission, and reflect compromises among the priorities of the RFMO’s member-countries. They also respond to expected annual changes in the harvestable-stock size and its distribution across the stock’s range. However the aperiodic El Nino phenomenon in the Pacific, and similar oceanic climate patterns in other regions, render subsequent season recruitment uncertain. Furthermore, the Commission’s regulations control harvest landings indirectly, mandating an industry-wide allowable fleet size (more precisely, “effort capacity``), which it allocates among the national fleets. Alternatively, it may limit total effort-time of harvesting, and allocate that among the coastal EEZs. Either way, it is constraining an input factor of harvest production, which is much easier--and far less expensive—than directly monitoring the harvest “landings” of individual fleets in various jurisdictions. These Commission regulations still permit national fishery management agencies to act to advance their individual interests and often-conflicting goals. Within Commission-imposed limits, each coastal nation may impose discriminatory limits on individual fleets’ access to its EEZ, and set discriminatory royalty rates for entry and effort-time of harvest. Also, within Commission and individual EEZ constraints, each fleet may distribute its allowable harvesting capacity advantageously. We formulate this in-season management process as a three-stage dynamic game, with Commission, coastal EEZs, and fleets acting consecutively. Backward induction yields the dynamic game’s subgame-perfect equilibrium. We go on to compare regulation through constraint of EEZs’ seasonal effort-time vs. regulation through restricting national-fleets’ effort capacities. Both coalition stability and realization of “virtual royalties” are examined. Finally we undertake a preliminary analysis of restoration of a degraded fishery, with initially depleted fish-stock and excessive harvesting capacity. Further work in this direction must recognize that capacity reduction is costly, and that fishery recovery time is dependent on uncertain trends in oceanic climatic conditions.