Time-varying Natural Mortality of Groundfish

Project Description

As part of the Stock Assessment Improvement Program, our first objective is to determine the circumstances under which time -varying natural mortality, M is estimable in an age-structured assessment model. We hypothesize that the precision of datasets is most important, especially survey data. The second objective is to compare the performance of estimating M with random effects versus using covariates. We hypothesize that using covariates increases precision unless M is misspecified. Thus, this proposal is responsive to two objectives of the Assessment Methods Working Group to conduct "investigations to develop best practices for addressing specific topics in stock assessments" an "investigations of the performance of assessment methods across a range of data availability and quality". Furthermore, this proposals "oriented to the broadly applicable thme" of the feasibility of estimating natural mortality, a topic that comes up in discussion of almost all stock assessments. 

Project Funding

National Marine Fisheries Service
Amount: $183,116
Start Date: 2014-08-00
End Date: 2016-07-00


Research Team

Terrance Quinn

Terrance Quinn

Principal Investigator

Professor Emeritus


  • fish population dynamics
  • estimation of animal and fish abundance
  • statistical time series analysis and sampling theory
  • renewable resource management systems
  • short courses on spreadsheet applications of population dynamics

Peter-John F. Hulson

Peter-John F. Hulson

Co-Principal Investigator


Research Staff

Phillip Ganz
M.S. student