In 2006, the Magnuson-Stevens Fishery Conservation and Management Act (MSA) was reauthorized and included additional requirements to prevent and end overfishing and rebuild overfished stocks. To comply with the additional statutory requirements, Regional Fishery Management Councils are to amend their fishery management plans to include a mechanism for specifying annual catch limits (ACL) for all fisheries at a level such that overfishing does not occur and to implement measures to ensure accountability (AM) for adhering to these limits. The MSA further directs that, unless otherwise provided for under an international agreement to which the U.S. participates, this mechanism must be established by 2010 for fisheries subject to overfishing, and by 2011 for all other fisheries.
The MSA requires the Council and NMFS to ensure long-term fishery sustainability by ending and preventing overfishing, and by rebuilding overfished stocks. In developing the national advisory guidelines for complying with National Standard 1 (NS1), NMFS established an operational framework to explain the relationship between Overfishing Limit (OFL), Acceptable Biological Catch (ABC), ACL, and Annual Catch Target (ACT) as they relate to maximum sustainable yield (MSY) and overfishing. Figure 1 illustrates the concepts and terminologies discussed in this section.
Figure 1. Relationship of the expected values of the long-term average MSY, OFL, ABC, ACL and ACT. [Click Image to Enlarge]
Maximum Sustainable Yield and Overfishing Limit
Maximum sustainable yield (MSY) is the maximum catch that can be harvested from a fishery on a continuing basis under prevailing conditions. If a stock or stock complex in a fishery is harvested on a continuing basis at MSY (corresponds to Fishing Mortality at MSY denoted by FMSY), its abundance will approach a long-term average biomass (corresponds to Biomass at MSY denoted by BMSY), at which it will fluctuate. MSY, FMSY and BMSY should be estimated for each stock based on the best scientific information available; however when such information is not available, these values should be estimated using proxies, to the extent possible.
Acceptable Biological Catch
Because MSY and OFL are estimates, there is an inherent level of uncertainty in the accuracy of these estimates due to scientific uncertainty in the information that is used in their calculation. Therefore, NS1 requires that an acceptable biological catch (ABC) limit be established at or below the OFL through the use of an ABC control rule to account for this uncertainty. Additionally, given the inherent uncertainty in the estimates in OFL, there is a probability (P) that the value set for ABC may exceed the true (but not precisely known) value of OFL, thus catch at ABC could actually result in overfishing. Therefore, when possible, ABC should be set such that P is less than some acceptable risk of overfishing (P*), as determined by the Council. According to NS1 guidelines, the probability that overfishing will occur cannot exceed 50 percent and should be a lower value. NS1 clarifies that it is the responsibility of the SSC to recommend the ABC to the Council.
Annual Catch Limits, Annual Catch Targets, and Accountability Measures
Once the OFL and ABC for a stock or stock complex are provided to the Council, it is the responsibility of the Council to determine the ACL. NS1 clarifies that the ACL may not exceed the ABC and may be set annually or on a multi-year basis. Under the NS1 guidelines, the ACL is purposely set at or below the ABC to further reduce the likelihood that annual catch equal to the ACL will exceed the ABC and OFL, and thus result in overfishing. The guidelines allow the Council to divide an ACL for a fishery into sector-ACLs. Examples of sectors include the commercial sector and recreational sector, or various gear groups within a fishery.
The ACL is also the level of annual catch of a stock or stock complex that serves as the basis for invoking AMs. AMs are management controls to prevent ACLs from being exceeded and to correct or mitigate overages of the ACL if they occur. AMs should address and minimize both the frequency and magnitude of overages, and correct the problems that caused the overage in as short a time as possible.
An ACT is an amount of annual catch of a stock or stock complex that is the management target of the fishery, and accounts for management uncertainty in controlling the actual catch to an amount that is at or below the ACL. Management uncertainty may include late catch reporting, misreporting, and underreporting of catches by fishery participants. The uncertainty is also affected by the ability of fishery managers to control the actual catch of a fishery.
Stocks Excepted from Annual Catch Limits and Accountability Measures
The MSA states that the ACL and AM requirements shall not apply to a fishery for species that have a life cycle of approximately 1 year unless the Secretary has determined the fishery is subject to overfishing. NS1 guidelines clarify that this exemption applies to a species for which the average length of time it takes for an individual to produce a reproductively active offspring is approximately 1 year and that the individual has only one breeding season in its lifetime. While exempt from the ACL and AM requirements, FEPs or FEP amendments for these stocks must have SDC, MSY, optimum yield (OY), ABC, and an ABC control rule. Additionally, the MSA provides an exception to the ACL requirement for stocks or stock complexes subject to management under an international agreement, which is defined as any bilateral or multilateral treaty, convention, or agreement that relates to fishing and to which the United States is a party. These excepted stocks still must have SDC and MSY specified.
For more details of the Annual Catch Limit specification requirements [Click Here]
To view the Omnibus Amendment establishing the ACL process [Click Here]
To view the Environmental Assessment for the Coral Reef Fishery ACL [Click Here]
To view the Environmental Assessment for the Main Hawaiian Island Deep 7 Bottomfish Fishery ACL [Click Here]
To view the Environmental Assessment for the Territory Bottomfish Fishery ACL [Click Here]
To view the Environmental Assessment for the Precious Coral and Crustacean Fishery ACL [Click Here]