Research Document - 2002/059

Analytical assessment and risk analyses for the stock of spring-spawning herring (Clupea harengus harengus L.) on the west coast of Newfoundland (NAFO Division 4R) in 2001.

By Grégoire, F., and Lefebvre, L.

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 34,632 t in 1997 to 55,141 t in 2001, a value above the minimum acceptable limit (BLIM) of 38,000 t and close to the buffer limit (BBUF) of 58,000 t. The SPA also reveals that fishing mortality among the oldest individuals (age 8 and older) exceeded the F0.1 threshold on a few occasions in the late 1960s and the early 1980s and almost continuously throughout the 1990s. Strict management measures applied since 1998 have helped to reduce this mortality significantly. The predicted catch corresponding to the F0.1 level in 2002 would be 6,763 t, and the catch corresponding to no reduction in biomass would be 5,800 t. With a catch of 6,763 t, the probability of an increase in biomass in 2003 would be less than 10 %. With a catch on the order of 5,800 t, this probability would increase to 50 %. These results should be interpreted cautiously, however, because they were obtained after an average abundance value was assigned to the recruits (age 2) in the 1998 to 2000 year-classes. The actual strength of these year-classes could not be assessed, because no acoustic survey was conducted in 2001.

Complete document (PDF, 1289 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.