Department of Fisheries Oceanography PhD Proposal Defense by Debra Duarte
When: Wednesday,
January 6, 2021
12:00 PM
-
1:00 PM
Where: > See description for location
Description: The School for Marine Science and Technology
Department of Fisheries Oceanography
PhD Proposal Defense
"Uncertainty in fishery observer data and estimates of discards"
By
Debra Duarte
Graduate Advisor:
Dr. Steven X. Cadrin (UMass Dartmouth - SMAST)
Committee Members:
Dr. Gavin Fay (UMass Dartmouth - SMAST)
Dr. Pingguo He (UMass Dartmouth - SMAST)
Dr. Anna Malak-Mercer (NOAA NEFSC)
Dr. Geret DePiper (NOAA NEFSC)
Wednesday, January 6, 2021
12:00 pm
via zoom
Abstract:
The goal of my dissertation is to improve confidence in discard estimates derived from at-sea fisheries observer and monitoring data by identifying the causes and effects of uncertainty, describing how that uncertainty can lead to biased catch estimates, and to provide approaches for reducing uncertainty during the sampling process and mitigating catch bias in the stock assessment and management analyses. Although my focus will be on the U.S. commercial fisheries covered monitored by the Northeast Fisheries Science Center, the outcomes should be applicable to any fisheries observing or monitoring program. My objectives can be expressed as four questions: Is there a problem with biased discard estimates in the New England groundfish fishery? What is the extent and magnitude of the problem? What are the effects on stock assessment and quota monitoring? and What can we do to correct the problem or minimize its effects? To answer these questions, we must clearly define the types of uncertainty in discard estimates and what causes them, because each source of uncertainty may require a specific solution. Once we have identified the possible sources of uncertainty, we need reliable methods to detect them. Then, we must evaluate how much uncertainty exists in discard estimates. Finally, we can focus on solutions to mitigate or prevent the problems. The first proposed chapter will evaluate existing methods for detecting observer effects. If the existing methods are found to be deficient, suggestions will be made to improve or combine the existing methods to produce a more powerful test. The second proposed chapter will focus on estimating the magnitude of catch uncertainty by predicting discard rates on unobserved trips. Important factors for investigation include ecological and economic components (e.g., stock size, fishing location, bottom habitat, season, fishing gear characteristics, vessel size, monitoring rate, and quota usage). The expected output is a range of potential discard amounts, which can be compared with existing estimates to determine how accurate the current estimates of removals are. The third proposed chapter will focus on the propagation of discard uncertainty through the stock assessment process and compare it with other sources of uncertainty. This is important to evaluate how much influence the catch data have on the assessment outputs, and whether the cost of increased precision (i.e., higher monitoring) is justified, or whether additional effort would be better expended in other research areas. The fourth proposed chapter will evaluate economic incentives for observer effects and observer falsification as observer coverage rates change. As we seek to improve catch estimates, it is important that we are not trading one type of uncertainty for another. This chapter will also consider alternate stratification schemes for either monitoring allocation or discard expansion.
A guiding principle throughout the proposed dissertation is the search for solutions that are cost effective while meeting the goals of the monitoring program.
************************************************************************************
https://umassd.zoom.us/j/95361250106?pwd=NHVoemkxbEFuVUw2eVZnbnNnUFpwZz09
Meeting ID: 953 6125 0106
Passcode: 513318
One tap mobile
+13126266799,,95361250106#,,,,,,0#,,513318# US (Chicago)
+16468769923,,95361250106#,,,,,,0#,,513318# US (New York)
Dial by your location
+1 312 626 6799 US (Chicago)
+1 646 876 9923 US (New York)
+1 301 715 8592 US (Washington D.C)
+1 346 248 7799 US (Houston)
+1 669 900 6833 US (San Jose)
+1 253 215 8782 US (Tacoma)
Meeting ID: 953 6125 0106
Passcode: 513318
Find your local number: https://umassd.zoom.us/u/actOQiNGjN
************************************************************************************
For additional information, please contact Sue Silva at s1silva@umassd.edu
Department of Fisheries Oceanography
PhD Proposal Defense
"Uncertainty in fishery observer data and estimates of discards"
By
Debra Duarte
Graduate Advisor:
Dr. Steven X. Cadrin (UMass Dartmouth - SMAST)
Committee Members:
Dr. Gavin Fay (UMass Dartmouth - SMAST)
Dr. Pingguo He (UMass Dartmouth - SMAST)
Dr. Anna Malak-Mercer (NOAA NEFSC)
Dr. Geret DePiper (NOAA NEFSC)
Wednesday, January 6, 2021
12:00 pm
via zoom
Abstract:
The goal of my dissertation is to improve confidence in discard estimates derived from at-sea fisheries observer and monitoring data by identifying the causes and effects of uncertainty, describing how that uncertainty can lead to biased catch estimates, and to provide approaches for reducing uncertainty during the sampling process and mitigating catch bias in the stock assessment and management analyses. Although my focus will be on the U.S. commercial fisheries covered monitored by the Northeast Fisheries Science Center, the outcomes should be applicable to any fisheries observing or monitoring program. My objectives can be expressed as four questions: Is there a problem with biased discard estimates in the New England groundfish fishery? What is the extent and magnitude of the problem? What are the effects on stock assessment and quota monitoring? and What can we do to correct the problem or minimize its effects? To answer these questions, we must clearly define the types of uncertainty in discard estimates and what causes them, because each source of uncertainty may require a specific solution. Once we have identified the possible sources of uncertainty, we need reliable methods to detect them. Then, we must evaluate how much uncertainty exists in discard estimates. Finally, we can focus on solutions to mitigate or prevent the problems. The first proposed chapter will evaluate existing methods for detecting observer effects. If the existing methods are found to be deficient, suggestions will be made to improve or combine the existing methods to produce a more powerful test. The second proposed chapter will focus on estimating the magnitude of catch uncertainty by predicting discard rates on unobserved trips. Important factors for investigation include ecological and economic components (e.g., stock size, fishing location, bottom habitat, season, fishing gear characteristics, vessel size, monitoring rate, and quota usage). The expected output is a range of potential discard amounts, which can be compared with existing estimates to determine how accurate the current estimates of removals are. The third proposed chapter will focus on the propagation of discard uncertainty through the stock assessment process and compare it with other sources of uncertainty. This is important to evaluate how much influence the catch data have on the assessment outputs, and whether the cost of increased precision (i.e., higher monitoring) is justified, or whether additional effort would be better expended in other research areas. The fourth proposed chapter will evaluate economic incentives for observer effects and observer falsification as observer coverage rates change. As we seek to improve catch estimates, it is important that we are not trading one type of uncertainty for another. This chapter will also consider alternate stratification schemes for either monitoring allocation or discard expansion.
A guiding principle throughout the proposed dissertation is the search for solutions that are cost effective while meeting the goals of the monitoring program.
************************************************************************************
https://umassd.zoom.us/j/95361250106?pwd=NHVoemkxbEFuVUw2eVZnbnNnUFpwZz09
Meeting ID: 953 6125 0106
Passcode: 513318
One tap mobile
+13126266799,,95361250106#,,,,,,0#,,513318# US (Chicago)
+16468769923,,95361250106#,,,,,,0#,,513318# US (New York)
Dial by your location
+1 312 626 6799 US (Chicago)
+1 646 876 9923 US (New York)
+1 301 715 8592 US (Washington D.C)
+1 346 248 7799 US (Houston)
+1 669 900 6833 US (San Jose)
+1 253 215 8782 US (Tacoma)
Meeting ID: 953 6125 0106
Passcode: 513318
Find your local number: https://umassd.zoom.us/u/actOQiNGjN
************************************************************************************
For additional information, please contact Sue Silva at s1silva@umassd.edu
Contact: > See Description for contact information
Topical Areas: School for Marine Sciences and Technology, SMAST Seminar Series