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• 1. [Article] A Kalman Filter Approach to Estimating Marine Turtle Incidental Take Risk

  A principle U.S. fisheries management concern is ensuring compliance with Endangered Species Act requirements to limit incidental takes of listed species to levels which do not result in potential jeopardy ...

  Citation × Citation Citation Abstract Copy Title: A Kalman Filter Approach to Estimating Marine Turtle Incidental Take Risk Author: Stohs, Stephen, Kvamsdal, Sturla A principle U.S. fisheries management concern is ensuring compliance with Endangered Species Act requirements to limit incidental takes of listed species to levels which do not result in potential jeopardy to existing population stocks. Part of the risk assessment process involves an analysis of historic takes (bycatch) of ESA-listed species relative to fishing effort. Sample bycatch per unit of effort (BPUE) ratios are used to gauge the take risk to ESA-listed species posed by future fishing effort. The rare-event nature of protected species takes complicates the interpretation of sample BPUE ratios. For illustration, a total of 23 leatherback turtles were incidentally taken by fishermen in the California-Oregon drift gillnet fishery from the 1990 through 2006 fishing seasons in 7733 sets of fishing effort, with from 0 to 5 leatherback takes per season over the entire period. Should one conclude the incidental take risk was significantly higher during the season with 5 leatherback turtle takes than in seasons with 0 takes? To address this and related inference problems, we specify a state space model which describes the pattern of observed takes as a Poisson process conditional on the level of fishing effort. A time-varying Poisson rate parameter, expressed as BPUE, measures the time-varying level of take risk. A Kalman filter for Poisson processes is used to estimate the intertemporal variation in take risk from California-Oregon drift gillnet fishery observer data. A key question regards attributing the observed pattern of takes to randomness which drives fluctuations in observed takes versus intertemporal variation in the level of take risk. Title: A Kalman Filter Approach to Estimating Marine Turtle Incidental Take Risk Author: Stohs, Stephen, Kvamsdal, Sturla A principle U.S. fisheries management concern is ensuring compliance with Endangered Species Act requirements to limit incidental takes of listed species to levels which do not result in potential jeopardy to existing population stocks. Part of the risk assessment process involves an analysis of historic takes (bycatch) of ESA-listed species relative to fishing effort. Sample bycatch per unit of effort (BPUE) ratios are used to gauge the take risk to ESA-listed species posed by future fishing effort. The rare-event nature of protected species takes complicates the interpretation of sample BPUE ratios. For illustration, a total of 23 leatherback turtles were incidentally taken by fishermen in the California-Oregon drift gillnet fishery from the 1990 through 2006 fishing seasons in 7733 sets of fishing effort, with from 0 to 5 leatherback takes per season over the entire period. Should one conclude the incidental take risk was significantly higher during the season with 5 leatherback turtle takes than in seasons with 0 takes? To address this and related inference problems, we specify a state space model which describes the pattern of observed takes as a Poisson process conditional on the level of fishing effort. A time-varying Poisson rate parameter, expressed as BPUE, measures the time-varying level of take risk. A Kalman filter for Poisson processes is used to estimate the intertemporal variation in take risk from California-Oregon drift gillnet fishery observer data. A key question regards attributing the observed pattern of takes to randomness which drives fluctuations in observed takes versus intertemporal variation in the level of take risk. Close

• 2. [Article] Risk Analysis in Setting Allowable Harvests: Annual Catch Limits under the Magnuson Stevens Reauthorization Act

  Under the reauthorized Magnuson-Stevens Act (MSRA), US fisheries management councils must specify an annual catch limit (ACL) for each managed species and institute accountability measures (AMs) to ensure ...

  Citation × Citation Citation Abstract Copy Title: Risk Analysis in Setting Allowable Harvests: Annual Catch Limits under the Magnuson Stevens Reauthorization Act Author: Semmens, Kathryn Alese, Anderson, Lee G. Under the reauthorized Magnuson-Stevens Act (MSRA), US fisheries management councils must specify an annual catch limit (ACL) for each managed species and institute accountability measures (AMs) to ensure that actual harvest will not cause the stock to be overfished. While the details of implementation are still being developed, a set of Proposed Guidelines for performing ACL analysis has been developed. The purpose of this paper is to provide a preliminary assessment of these guidelines. The MSRA specifies two principles to be used as a framework for determining how Councils can comply with the ACL and AM measures. Both deal with uncertainty in the overall fisheries management process. The first is the separation between science and policy in setting the upper level on allowable harvests. The second is the requirement to take strong management actions to ensure that, given real world enforcement issues, the actual harvest in any year does not surpass the allowable harvest level. The procedure for applying the principles is quite complex and it goes beyond a strict interpretation of the written language in the law. However, it is consistent with current procedures and with commonly accepted principles in fisheries management policy. The Proposed Guidelines suggest that a distinction be made between scientific and implementation uncertainty. While the distinction may follow from the two principles, a preliminary look at the logical process of developing the required control rules for specifying Acceptable Biological Catch and Annual Catch Targets raises questions about the usefulness of this distinction in actual policy analysis. Title: Risk Analysis in Setting Allowable Harvests: Annual Catch Limits under the Magnuson Stevens Reauthorization Act Author: Semmens, Kathryn Alese, Anderson, Lee G. Under the reauthorized Magnuson-Stevens Act (MSRA), US fisheries management councils must specify an annual catch limit (ACL) for each managed species and institute accountability measures (AMs) to ensure that actual harvest will not cause the stock to be overfished. While the details of implementation are still being developed, a set of Proposed Guidelines for performing ACL analysis has been developed. The purpose of this paper is to provide a preliminary assessment of these guidelines. The MSRA specifies two principles to be used as a framework for determining how Councils can comply with the ACL and AM measures. Both deal with uncertainty in the overall fisheries management process. The first is the separation between science and policy in setting the upper level on allowable harvests. The second is the requirement to take strong management actions to ensure that, given real world enforcement issues, the actual harvest in any year does not surpass the allowable harvest level. The procedure for applying the principles is quite complex and it goes beyond a strict interpretation of the written language in the law. However, it is consistent with current procedures and with commonly accepted principles in fisheries management policy. The Proposed Guidelines suggest that a distinction be made between scientific and implementation uncertainty. While the distinction may follow from the two principles, a preliminary look at the logical process of developing the required control rules for specifying Acceptable Biological Catch and Annual Catch Targets raises questions about the usefulness of this distinction in actual policy analysis. Close

• 3. [Article] Important Factors Influencing Rule Compliance in Fisheries Lessons from Danish Fisheries

  This paper presents the results of a research project, which has focused on Danish fishers’ acceptance of imposed fisheries regulations and their respect for the management system. The analytical framework ...

  Citation × Citation Citation Abstract Copy Title: Important Factors Influencing Rule Compliance in Fisheries Lessons from Danish Fisheries Author: Mathiesen, Christoph, Nielsen, Jesper Raakjaer Year: 2001 This paper presents the results of a research project, which has focused on Danish fishers’ acceptance of imposed fisheries regulations and their respect for the management system. The analytical framework developed by Raakjær Nielsen (1998) and Raakjær Nielsen and Vedsmand (1999) has been used. The research has focused on three Danish fisheries: the cod fishery in the Baltic Sea, the demersal and Nephrops fishery in Kattegat and the fishery for non-human consumption species in the North Sea. The research is based on interviews with 56 fishers and a mail survey covering all vessels in the three selected fisheries. The following factors are concluded to have a major impact on rule compliance in fisheries: 1) the economic gains to be obtained; 2) the risk of being detected and the severity of the sanction; 3) the compatibility between the content of the regulation and the fishing patterns and practise; 4) regulation leads towards stock conservation; 5) norms, in particular the behaviour of other fishers and the moral of the individual fisher. In addition there are some indication, that co-management is important for rule compliance. Title: Important Factors Influencing Rule Compliance in Fisheries Lessons from Danish Fisheries Author: Mathiesen, Christoph, Nielsen, Jesper Raakjaer Year: 2001 This paper presents the results of a research project, which has focused on Danish fishers’ acceptance of imposed fisheries regulations and their respect for the management system. The analytical framework developed by Raakjær Nielsen (1998) and Raakjær Nielsen and Vedsmand (1999) has been used. The research has focused on three Danish fisheries: the cod fishery in the Baltic Sea, the demersal and Nephrops fishery in Kattegat and the fishery for non-human consumption species in the North Sea. The research is based on interviews with 56 fishers and a mail survey covering all vessels in the three selected fisheries. The following factors are concluded to have a major impact on rule compliance in fisheries: 1) the economic gains to be obtained; 2) the risk of being detected and the severity of the sanction; 3) the compatibility between the content of the regulation and the fishing patterns and practise; 4) regulation leads towards stock conservation; 5) norms, in particular the behaviour of other fishers and the moral of the individual fisher. In addition there are some indication, that co-management is important for rule compliance. Close

• 4. [Article] Power, Fish, and the Greenhouse on the Columbia River

  The Columbia River in the Pacific Northwest region of the U.S. is home to the greatest hydroelectric system in the world. Its dams provide 75 percent of the power needs of nearly 10 million people. But ...

  Citation × Citation Citation Abstract Copy Title: Power, Fish, and the Greenhouse on the Columbia River Author: Buchanan, Shepard C. Year: 2001 The Columbia River in the Pacific Northwest region of the U.S. is home to the greatest hydroelectric system in the world. Its dams provide 75 percent of the power needs of nearly 10 million people. But the dams also create numerous obstacles to the survival of what was once the world’s greatest salmon fishery. The region spends over $500 million annually to try to restore the fishery and ensure its future survival. However, the changes in river operations implemented to meet fish needs make it much more difficult to meet other environmental goals, such as the development of renewable electric power resources. Renewable resources would help to alleviate the risks associated with global warming. This paper demonstrates an unfortunate irony: that the renewable resources advocated by environmental interests are incompatible with a hydro system that is operated for fish. Such resources could add billions of dollars to the costs of electric power, while providing minimal environmental benefits. Saving the fish and reducing greenhouse gases are two environmental goals that do not appear to be compatible. Title: Power, Fish, and the Greenhouse on the Columbia River Author: Buchanan, Shepard C. Year: 2001 The Columbia River in the Pacific Northwest region of the U.S. is home to the greatest hydroelectric system in the world. Its dams provide 75 percent of the power needs of nearly 10 million people. But the dams also create numerous obstacles to the survival of what was once the world’s greatest salmon fishery. The region spends over $500 million annually to try to restore the fishery and ensure its future survival. However, the changes in river operations implemented to meet fish needs make it much more difficult to meet other environmental goals, such as the development of renewable electric power resources. Renewable resources would help to alleviate the risks associated with global warming. This paper demonstrates an unfortunate irony: that the renewable resources advocated by environmental interests are incompatible with a hydro system that is operated for fish. Such resources could add billions of dollars to the costs of electric power, while providing minimal environmental benefits. Saving the fish and reducing greenhouse gases are two environmental goals that do not appear to be compatible. Close