Research Document - 2012/025

Limit Reference Point for Southwest Nova Scotia / Bay of Fundy Spawning Component of Atlantic Herring, (Clupea harengus) (German Bank and Scots Bay)

By D.S. Clark, K.J. Clark, R. Claytor, S. Leslie, G.D. Melvin, J.M. Porter, M.J.Power, H.H.Stone, and C.Waters

Abstract

In accordance with the Terms of Reference for the meeting, the available data were examined in order to determine candidates for a limit reference point for the Southwest Nova Scotia / Bay of Fundy Spawning Component of Atlantic Herring, Clupea harengus, and a rationale is provided for the recommended values. Five sources of information are discussed in this research document: historical stock status advice; the presence or absence of spawning components; the fate of individual year classes (cohorts) over time (mortality rate trends and proportion of juvenile fish); historical landings; and acoustic survey relative index.

With the evidence of the decline in spawning grounds, targeting of juveniles in the fishery, declines in catches, as well as the science advice indicating the need for rebuilding, it is proposed that the 2005 to 2010 average acoustic survey value be identified as the conservation limit reference point for Southwest Nova Scotia / Bay of Fundy herring (German Bank and Scots Bay). The stability at the 2005-2010 level is support for this as the limit reference point and provides data from which to select a point, below which, the risk of serious harm is unacceptable. Other considerations that lead to the selection of this point relate to the objective of avoiding negative impacts to the ecosystem and long-term loss of fishing opportunities. Ecosystem considerations include herring's role as a forage fish, and long-term loss of fishing opportunities in the case of stock collapse and possible decades required for recovery to occur.

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