Open Access (Hackett, 1998, chapters 4 and 5). A state of affairs that exists when there are no property rights systems recognized that constrain access to a resource or withdrawals of resource units, typically for a natural resource.

Open Access Equilibrium (Allen, 1999). In fisheries, an open access equilibrium is said to exist when all of the excess profits or economic rent that attracts new entrants to a developing fishery have been dissipated in the costs associated with the additional fishing effort. If resource and market conditions remain stable, the fishery will remain in equilibrium because the fishery is no more attractive to new entrants than any other business, and the rate of exist balances the rate of entry. Fisheries can be in equilibrium at various levels of production compared to their potential. The classic open-access equilibrium point in fisheries occurs when fishing effort is higher than that which will obtain the greatest yield from a fishery, whether yield is measured in volume, in revenue, or in profit. Reductions in fishing effort from that point are expected to produce higher landings, more revenue, and higher profits.

Opportunity Cost (Hackett, 1998, chapters 1 and 6). When a scarce resource, good, or service is allocated to one use, the opportunity cost of that allocation represents the value of the best alternative that was foregone. (If a boat owner has a chance to use his boat for some productive purpose when the boat would otherwise be sitting at the dock doing nothing, the opportunity cost for the boat is 0. If the boat would be making $1,000 day fishing, its opportunity cost would be $1,000.)

Opportunity Cost of Capital (Hackett, 1998, chapter 12). When a firm is considering a capital investment, such as expanding production capacity, the investment is anticipated to generate a flow of added income. The opportunity cost of that capital investment is the income that can be earned by investing the money in some other income-generating asset, like stocks, bonds, or alternative projects. For example, if the next best use of invested capital is to buy U.S. Treasury Bonds paying a 7 percent annual return, then every dollar invested in the particular capital project has an opportunity cost of generating 7 percent return each year.

Opportunity Cost of Labor (Allen, 1999). The wages that would be paid to a worker in his next best alternative work opportunity. In a region with high unemployment, the opportunity cost of labor would be low, possibly approaching the amount that a worker would be paid when collecting unemployment insurance or welfare. In a region with a tight labor market, the opportunity cost of labor would be high. If someone works at a job that pays them less than their opportunity cost, they are losing money, but may be satisfied for reasons other than money. In evaluating sole proprietorship businesses, like many fishing boats, it is useful to establish the owner-operator's opportunity cost in order to separate returns to labor from returns to capital.

Optimum Sustainable Yield (King, 1995). A level of yield consistent with the biological capacity of the stock (therefore usually less than MSY), which takes into account economic, sociological, and environmental factors -- a concept that relies on 'optimum' being given specific meaning. (Optimum means different things to different people.)

Output Controls (King, 1995). Limitations on the weight of the catch (a quota), or the allowable size, sex, or reproductive condition of individuals in the catch.

Positive Externality (Hackett, 1998, chapters 5 and 6). See the "externalities" entry.

Present Discounted Value (Hackett, 1998, chapters 5 and 6). The present value of a future benefit or cost. Because people (and thus firms as well) have positive discount rates (they prefer money today compared to next year) (see the "discount rate" entry), the present discounted value of a future benefit or cost is smaller than the dollar amount of the payment in the future.

Private Property Rights (Hackett, 1998, chapter 4). Usually refers to a bundle of rights of ownership possessed by an owner that includes the rights of access, withdrawal (or resource units), management, exclusion (of others from using the resource), and alienation (right to sell ownership to someone else).

Producer Surplus (Hackett, 1998, chapter 3). The seller's share of the gains from trade. The area between price and a seller's minimum sales price (usually marginal cost).

Public Choice (Hackett, 1998, chapter 7). A form of political economic analysis that treats politicians as any other self-interested maximizer having an objective function that might include current and discounted future income, re-election, or power and control. Thus the rational behavior of a politician is predicted to be in a manner that is consistent with his or her objectives.

Pure Public Good (Hackett, 1998, chapter 5). A good or service that (1) is used by multiple people, and (2) for which use by one does not subtract from what is available for others to use. The latter characteristic distinguishes pure public goods from common-pool resources. An example of a pure public good is public radio or public television broadcasts.

Rational Choice (chapters 1 and 7). From the perspective of economics, a choice is rational if it is consistent with the objectives and preferences of those making the decision, given the available information. An allocation choice is economically rational if it is seen as yielding a benefit that exceeds opportunity cost.

Recruitment (King, 1995). The addition of young fish to a stock. (Generally, recruitment refers to the time at which young fish enter the fishable stock.)

Recruitment Overfishing (King, 1995). A level of fishing in which the adult stock is reduced to the extent that recruits produced are insufficient to maintain the population. (Recruitment overfishing leads to stock collapse. The relationship between adult stock and recruitment is not well understood for many marine species. But, as biologists like to say, we know that the stock-recruitment curve passes through zero -- meaning that we do know that if there are zero adults, there will be zero recruitment.)

Renewable Resources (Hackett, 1998, chapter 6). The class of resources that are capable of replenishing themselves over time. Excessive harvest can deplete the reproductive capacity of a renewable resource.

Rent Dissipation (Hackett, 1998, chapter 5). In the context of natural resources, dissipation of Hotelling rents (named after economist H. Hotelling) occurs when current consumption rates exceed the dynamically efficient consumption rate. In the context of common-pool resources (such as fisheries), this outcome has been described by Garrett Hardin as the tragedy of the commons. (See also "Super Profits (economic rent" below.)

Scarcity (Hackett, 1998, chapter 1). Something is said to be scarce when, at zero price, more is wanted than is available.

Social Capital (Hackett, 1998, chapter 11). As the concept is used by sociologist James Coleman and political scientist Robert Putnam, refers to the stock of "civic virtues" and networks of civic engagement, involvement, reciprocity norms, trust, volunteerism, and sharing essential to democratic communities.

State Property Rights (Hackett, 1998, chapter 4). In democratic systems, property owned by the citizens of a political unit who assign rule-making authority to a state agency.

Sunk Costs (Hackett, 1998, chapter 7). Costs that cannot be salvaged if an activity is ended. For example, if a worker invests time and effort in learning a work routine that is highly specific to a particular employer, then the costs associated with developing workplace skills are sunk and thus cannot be salvaged if the worker quits and moves elsewhere. Such a situation gives bargaining power to the employer.

Super Profits (economic rent) (King, 1995). Profits above those needed to make a return on investment, when compared with the returns which could be generated in other sectors. (The term "excess profits" is also used to describe a situation in which an economic activity produces profits in excess of the normal profits that are necessary to keep firms in the business. In fisheries, the generation of these economic rents is generally considered to be desirable, because the fishery is most efficient when economic rents are maximized. The existence of excess profits in a fishery with open access (no property rights) attracts additional fishing firms until the excess profits or economic rents are all dissipated by the excess input costs that are used in capturing the same amount of fish.)

Sustainability (Hackett, 1998, chapter 11). A community's control and prudent use of natural, human, human-made, social, and cultural capital to foster economic security and vitality, social and political democracy, and ecological integrity for present and future generations. Ecological sustainability more narrowly focuses on maintaining and enhancing ecological integrity and biodiversity, and generally on protecting the life-support and waste-sink functions of the earth. Technology Creep (King, 1995). A gradual increase in the efficiency of fishing gear and methods, which results in an increase in effective fishing effort. (If a fishery conservation plan attempts to control fishing effort (input control) as a means to protect the stock, technology creep can undermine the conservation plan, because effective fishing effort continues to increase, even though nominal fishing effort (the number of boats, days, traps, etc.) remains constant. In the lobster fishery, various technological advances are being touted as helping fishermen to maintain or increase catches in spite of trap limits. To the extent that these gimmicks work, technology creep will counteract the intended conservation effect of the trap limits.)

Total Net Benefit (Hackett, 1998, chapter 6). Total benefit minus total cost. (Changes in public policy entail both costs and benefits. Total net benefit is an attempt to calculate the extent to which the benefits of a policy change will outweigh the costs.)

Total Surplus (Hackett, 1998, chapters 3 and 4). Another name for the aggregate gains from trade in markets. (Total surplus is generally considered to be the sum of consumers' surplus and producers' surplus. Attempts to rebuild fisheries are often justified on economic grounds because the expectation is that consumers will get more fish at a lower price than they were willing to pay, thus creating consumers' surplus, and fishermen are expected to receive a price that more than covers their costs, thus creating producers' surplus. Added together, these create a positive total surplus.)

Tragedy of the Commons (chapter 5). A term coined by Garrett Hardin for excessive appropriation from a common-pool resource that occurs because (1) each user imposes appropriation externalities on the others, and (2) governance structures that might limit appropriation to sustainable levels are inadequate or lacking. See the "rent dissipation" entry.

Transaction Costs (Hackett, 1998, chapters 3 and 6). The costs of making, measuring, and enforcing agreements.

Vulnerability (King, 1995). The proportion of fish in a fishing gear's area of influence that is retained by the gear.

Yield Per Recruit (Allen, 1999). The expected yield in weight that will be obtained by the fishery from an individual fish coming into the population. At young ages, fish are growing faster than they are dying. As they get older, higher death rates counterbalance growth. If fish are har