Research Document - 2004/090

Analytical assessment and risk analyses for the spring spawning herring (Clupea harengus harengus L.) stock of the west coast of Newfoundland (NAFO Division 4R) in 2003

By Grégoire, F., L. Lefebvre, J. Lavers

Abstract

The results of a Sequential Population Analysis (SPA) reveal that the spawning biomass of the spring spawning stock of Atlantic herring (Clupea harengus harengus L.) in NAFO Division 4R appears to have risen from a record low of 32,559 t in 1997 to 57,727 t in 2003 and 52,582 t in 2004. The spawning stock biomass calculated for 2004 exceeds the minimum acceptable limit B_LIM of 37,831 t but is below the buffer limit B_BUF of 57,453 t. The SPA reveals that the herring became significantly more abundant in the late 1960s and the mid-1980s. The SPA also reveals that fishing mortality among the oldest individuals (age 8 and older) exceeded the F_0.1 threshold on a few occasions in the late 1960s and the early 1980s and almost continuously throughout the 1990s. For an exploitation rate of 24 % (F_0.1), the expected catches in 2004 would be close to 10,000 t. However, a decline of
8 % of the spawning stock biomass would be observed at this same catch level. For this stock, the probabilities of exceeding F_0.1 in 2004 would be less than 50 % for catches of less than 10,000 t.

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