Terms of Reference

Assessment framework for the Atlantic Herring stock of the southern Gulf of St. Lawrence (NAFO Div. 4T)

Regional Peer Review – Gulf Region

April 13-15, 2015
Moncton, New Brunswick

Chairperson: Gérald Chaput (DFO Gulf Region)

Context

The peer review meeting of the assessment of Atlantic herring in the southern Gulf of St. Lawrence conducted in March 2014 identified issues with the indices of abundance from the gillnet fisheries and assessment models. Two assessment models that varied in the assumptions about catchabilities in the gillnets for ages 4 and 5, presumably associated with observed declines in weight at age, were examined. The estimated absolute biomass values differed substantially between models although the trends in abundance from both models were the same (DFO 2014). As a result, catch advice for the fall spawner component of Atlantic herring was only provided for the 2014 fishery (DFO 2014). A framework review of the assessment approach was recommended to address the identified shortcomings and to review alternative model formulations. Based on the conclusions and recommendations of this framework review, catch advice for fall spawners for the 2015 fishery would be provided in April 2015. The framework review would also address the assessment model and assumptions for the spring spawner component.

Objectives

The framework review of assessment methodology for the Atlantic herring stock of the southern Gulf of St. Lawrence will address the following objectives:

• review existing abundance indices and their analytical methods,
• review evidence for changes in selectivity in the commercial indices of abundance associated with changes in size at age or other factors (environmental).
• review alternative modelling approaches for the indices or development of new indices
• review of industry led spawning bed acoustic projects as spawning bed specific indices of abundance
• review of evidence for changes in natural mortality of Atlantic herring in the southern Gulf of St. Lawrence
• review of completeness of the reported landings from all gear sectors and seasons
• review of current and new population models to estimate biomass of Atlantic herring to be used for the provision of catch advice, including options for spawning location specific models of abundance
• review methods used to develop the current reference points for Atlantic herring and advise on the need to revise the methods and to provide revised reference points taking into consideration revised or alternative assessment methods and trends in population dynamics for this stock.
• identification of knowledge gaps and research to improve the assessment of abundance and development of catch advice for Atlantic herring from the southern Gulf of St. Lawrence.

Expected publications

• CSAS Proceedings report summarizing the conclusions and recommendations of the assessment framework.
• CSAS Research Document(s).

Participation

• DFO Science Branch
• DFO Fisheries Management
• External experts (to DFO)

References

DFO. 2014. Assessment of Atlantic herring in the southern Gulf of St. Lawrence (NAFO Div. 4T) to 2013. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2014/040.