Statistical Catch-At-Length assessment results for Sebastes mentella and S. fasciatus in Units 1 and 2

Past attempts at Statistical-Catch-At-Length assessments for the redfish populations in Units 1+2 have struggled to reconcile survey biomass trends with survey catch-at-length data. Here it is shown that reconciliation is possible under the assumptions of natural mortality decreasing with age, and a...

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Bibliographic Details
Main Authors: Rebecca A Rademeyer, Doug Butterworth
Format: Report
Language:unknown
Published: 2022
Subjects:
Biological Mathematics
Applied Statistics
Biostatistics
Canadian redfish populations
statistical catch-at-length (SCAL) assessment
fisheries resource management
catch-at-length data
assessment models
stock assessment models
Sebastes mentella
Online Access:https://doi.org/10.25375/uct.19114769.v1
https://figshare.com/articles/report/Statistical_Catch-At-Length_assessment_results_for_Sebastes_mentella_and_S_fasciatus_in_Units_1_and_2/19114769
Description
Summary:Past attempts at Statistical-Catch-At-Length assessments for the redfish populations in Units 1+2 have struggled to reconcile survey biomass trends with survey catch-at-length data. Here it is shown that reconciliation is possible under the assumptions of natural mortality decreasing with age, and a situation where only occasionally extraordinarily strong year classes enter the populations. While the species-disaggregated assessments developed here could be refined (and species-aggregated), it is suggested that first discussions should be held to agree or otherwise on the reasonableness/plausibility of these core aspects of the dynamics of these species. The situation of occasional extraordinarily strong year classes has implications, which are discussed, for the basis under which reference points for these populations are best evaluated.

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