Research Document - 2015/029

An Assessment Framework and Review of Newfoundland east and south coast Atlantic Herring (Clupea harengus) stocks to the spring of 2013

By C. Bourne, F. Mowbray, B. Squires, and J. Croft

Abstract

The stock status of Newfoundland east and south coast Atlantic Herring (Clupea harengus) has been assessed since 2000 primarily using an abundance index derived from the fishery‑independent spring research gillnet program, along with data from logbooks, telephone surveys and the commercial fishery. The methodology used to collect and analyze these data has been focused on the spring‑spawning stock component, which historically comprised the majority of the population, with fall spawners composing the remainder. However, during the past decade the composition of the four assessed stock complexes (White Bay‑Notre Dame Bay, Bonavista Bay‑Trinity Bay, St. Mary’s Bay‑Placentia Bay and Fortune Bay) changed significantly, with the proportion of fall spawners in each area increasing to as high as 90%, largely due to declines in abundance of spring-spawning herring. During the 2011 stock assessment it was recommended that assessment methodology for the region should be reviewed and modified to reflect these stock composition changes; this document describes a special assessment framework meeting that was conducted in the fall of 2013 to address that recommendation. Components reviewed during the meeting included: stock structure, spawning stock composition, commercial and biological sampling procedures, aging protocols, indices of abundance, and models to assess stock status. The decline of spring-spawning herring, apparent shifts in distribution and spawning times, and the reductions to the research gillnet program in 2013 and its utility as an index were highlighted; abundance indices were also updated for each stock area. Numerous recommendations were made to improve assessments going forward, including splitting abundance indices by spawning group when possible, re-evaluating spawning group designations, examining the timing and gear selectivity in the research gillnet program and exploring the influence of environmental variables on the stock structure and recruitment of Newfoundland herring. These recommendations will be addressed in the next stock assessment to be held in 2015.

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