Assessment methods for stocks with little or no age data

A workshop on the best possible stock assessment models for fish stocks that do not have annual ageing programs or data.

Event details

Date & Time:
October 24, 2023 8:00 AM
October 27, 2023 4:00 PM
St. John's, Canada
Registration Deadline:
September 10, 2023

There are many fish stocks in Canada and elsewhere that do not have annual ageing programs, or any age information.

Improving our understanding and progress in the development of data-moderate state-space stock assessment models (SSAMs) is an important step to extend SSAMs beyond data-rich age-based approaches.

This workshop will focus on the best possible stock assessment models for these cases.


The purpose of this four day workshop is to review current scientific information regarding the development and application of data-moderate SSAMs (e.g., little or no age data).

Workshop format

  • This is an in-person development workshop at Memorial University.
  • It is not a training workshop, although talks will be recorded and made available upon request, with the approval of presenters.

Invited speakers (tentative)

  1. Anders Nielsen, National Institute of Aquatic Resources, Denmark
  2. Fan Zhang, College of Marine Science, Shanghai Ocean University, China
  3. Daniel Howell, Institute of Marine Research, Norway
  4. Giancarlo Correa, AZTI, Spain


Register by September 10, 2023 by emailing Noel Cadigan.

Attendance will be limited and will be confirmed by September 10, 2023.


A formal agenda will be circulated as the meeting date approaches, but early challenges to be addressed and discussed include how to model:

  • stochastic growth rates (i.e., distribution of length-at-age),
  • time-varying growth rates,
  • catch-at-length,
  • recruitment period,
  • within-year growth,
  • within-year distribution of fishing effort,
  • changes in survey protocols,
  • what to do if fishery length compositions are not available,
  • other computational issues.

The workshop will review progress on assessment models for several east coast of Canada stocks, and stocks in other areas:

  1. NAFO Divisions 3LN and 3O redfish.
  2. 2J3KL and 3NO witch flounder
  3. 3LNOPs thorny skate
  4. Others TBD

Participants are encouraged to suggest additional case studies/presentations and topics to the steering committee.

Discussions will include research priorities and future collaborations. A meeting report will be produced. A workshop objective is to initiate a perspectives paper on application of length-based models (benefits and challenges), and possibly a simulation comparison paper of various methods. These details will be finalized before and at the workshop.

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