Provisions of the Magnuson-Stevens Fishery Conservation and Management Act (MSFCMA, P.L. 94-265 , as amended; 16 U.S.C. §§1801 et seq.) added during the 1996 reauthorization and amended in 2006, included specific requirements to end overfishing and to rebuild overfished stocks. To implement these requirements, the MSFCMA directed the National Marine Fisheries Service (NMFS) (also referred to as NOAA Fisheries) within the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce to develop regulations by 2008 to provide guidance for establishing annual catch limits (ACLs) and related biological benchmarks. By the end of 2011, a requirement to implement ACLs and end overfishing in all federally managed fisheries came into effect. For fish stocks at low levels of abundance, stock rebuilding within a 10-year time frame (with some exceptions) is also required. Many commercial fishermen question whether the current provisions of the MSFCMA and their implementation by NMFS adequately reflect the complexities and related uncertainties associated with the management of fish stocks. Many commercial fishermen believe they are being held to an impossibly high standard because fishing mortality is only one of many factors that affect stock abundance. Other factors, including environmental conditions and fish habitat degradation, are often beyond managers' and fishermen's control. Furthermore, they assert that assessments of fish stocks are often flawed or incomplete because of inadequate data and simplistic population models. Many fishermen explain that rebuilding schedules and population benchmarks are set on a strict timetable and at specific levels, but the outcomes of theses management measures are subject to a high level of uncertainty. From their perspective, the fishing industry is sometimes left to endure the economic and social consequences of lower revenues and fewer fishing opportunities when harvest restrictions are implemented to satisfy MSFCMA rebuilding requirements. Environmentalists counter that overfishing and previous management failures illustrate the need to maintain established fish stock rebuilding schedules. They maintain that the lack of progress preceding the recent changes to the MSFCMA in 2006 was due to the failure of many fishery management plans to reduce exploitation sufficiently to end overfishing. They assert that absent stringent limits for rebuilding, managers too often put off the short-term reduction in catch necessary for stocks to recover. They emphasize that relatively short-term sacrifices associated with rebuilding will result in long-term economic gains to recreational and commercial fishermen. Several different bills related to overfishing and stock rebuilding have been introduced during the 112 th Congress. H.R. 3061 and S. 238 would require preparation of fishery economic impact statements to evaluate whether fishery management plans provide for the sustained participation of fishing communities. H.R. 1646 , H.R. 3061 , and S. 632 include in part, identical language which would increase management flexibility when rebuilding fish stocks. H.R. 2304 , H.R. 3061 , and S. 1916 include provisions that would address concerns related to generating and using scientific information. S. 2184 and H.R. 4208 would amend the Saltonstall-Kennedy Act (15 U.S.C. 713c-3) to provide directed funding for fisheries management and research. H.R. 2304 , H.R. 3061 , and S. 1916 would exclude stocks or fisheries from ACL requirements under specific circumstances, and H.R. 1646 would impose certain conditions before fishery closures could be implemented. Several hearings have been held to explore broad concerns related to overfishing, ACLs, and the related need to reduce uncertainty by improving fisheries data collection and stock assessments. The most recent was held on December 1, 2011, by the House Committee on Natural Resources, which considered a variety of bills and associated issues related to fisheries, including H.R. 1646 , H.R. 2304 , and H.R. 3061 . No further congressional action has been taken by either the House or the Senate. Living resources such as fish replenish their populations through reproduction and growth that balance losses to the population from predation and other causes of natural death. An unfished population is assumed to be at or near its carrying capacity—the maximum amount of a fish species that can live in an area. At carrying capacity, one or more of the living requirements for the population such as space, food, shelter, or other environmental factors is fully utilized, and along with predation and natural mortality, limits further growth of the population. As shown in Figure 1 , the size of an unfished population reaches its natural limit at carrying capacity. At this point, populations are usually composed of relatively large numbers of older and slower-growing individuals. Although fish may produce thousands of eggs each time they spawn, at carrying capacity (on average) only two fish survive to reproduce from the offspring of each spawning pair. When fish are harvested from the population (usually older, larger individuals), more resources become available for other segments of the population. The population becomes increasingly productive because it includes a higher number of younger, faster-growing individuals. Surplus production is the amount of fish that may be removed on a continuing basis at different biomass or stock levels. At equilibrium, the surplus production shown in Figure 2 is the level of population growth that will just replace the amount of fish that are harvested. Population growth approaches zero at carrying capacity and at low stock levels. Surplus production is maximized at maximum sustainable yield (MSY), the fish population level at which the greatest stock growth level is realized. The basic goal of fisheries managers is to retain sufficient biomass to generate future reproduction and growth of the stock while meeting fishery management objectives related to maintaining a desired harvest level. Fisheries managers use stock assessments to estimate the status of fish stocks as a basis for determining the level of harvest that may be taken within specific time periods. There are many types of stock assessments, with differing data requirements and levels of potential accuracy. Generally, both fishery-related (fishery-dependent) and biological (fishery-independent) data are needed to develop an assessment of fish populations. Some examples of fishery-related information include the weight of landings, the ages of landed fish, the ratio of males to females in the catch, and fishing effort expended by fishermen, while biological information might include the age at first spawning, the natural mortality of the stock, growth rate of fish, and fecundity (the average number of eggs a fish may produce). Different models may be used for management of species depending on what data are available. Most models require extensive information, with associated costs that increase as additional data is collected to improve accuracy. Many factors influence biological processes and fish abundance, including the quality and quantity of fish habitat, environmental changes, predation, and ecosystem composition. These constantly changing factors confound the ability of fisheries managers to develop accurate predictive models of fish populations. Managers face the challenge of recommending fishing at or below MSY without precise knowledge of the current stock population level. In addition to uncertainty regarding the current location on the sustainable growth curve ( Figure 2 ), environmental changes shift the growth (sustainable yield) curve up or down. When considering management goals and associated actions, there is an important distinction between stopping overfishing and rebuilding overfished populations. Overfishing is defined by the percentage of fish harvested (rate of removals), while an overfished stock is determined by the abundance or biomass of the stock. Assuming adequate information is available, overfishing can be stopped by reducing fishing effort, but returning a stock from an overfished condition requires rebuilding to a target biomass level. Overfishing reduces fish stock abundance, threatens and alters coastal and marine ecosystem productivity, and reduces economic returns from commercial and recreational fisheries. If all stocks were rebuilt and harvested at maximum sustainable yield, NOAA estimates that the value of commercial landings could be increased by $2.2 billion. However, some would argue that it may not be biologically possible, or that it is at least unlikely, to achieve these optimal levels for all stocks simultaneously, especially for multispecies fisheries. The MSFCMA, in Section 304(e)(1), requires NMFS to report annually to Congress on the status of fisheries managed under the act. Of the 258 stock or stock complexes for which an overfishing determination could be made, 36 were subject to overfishing, while of the 219 stock or stock complexes for which an overfished determination could be made, 45 were classified as overfished. However, the overfishing thresholds of 279 stocks and stock complexes and the overfished thresholds of 318 stocks and stock complexes were not known, defined, or applicable. Table 1 and Table 2 provide overfishing and overfished designations by fishery management regions. Since 2000, 27 overfished stocks have been rebuilt, including several notable examples such as Northeast scallop, mid-Atlantic bluefish, and Pacific lingcod. In contrast to overfishing, managers have much less control over the biomass (abundance) of stocks. In addition to removals from the stock by harvesting, fish stocks vary because of a variety of environmental factors, such as water temperature, currents, availability of food, and abundance of predators. The relationship between stock abundance and productivity, especially recruitment of fish to the population, is often unpredictable and is poorly understood for many species. Management actions to increase spawning biomass may improve the probability of greater recruitment and stock growth, but it cannot guarantee stock rebuilding, because environmental conditions are constantly changing. Furthermore, historical abundance may not be a good indicator of the current capacity of the ecosystem to sustain a specific level of stock abundance. Exogenous factors such as natural cycles, global climate change, and loss or degradation of fish habitat also affect fish productivity and may reduce carrying capacity from historic norms.