Research Document - 2010/092

Assessment of Atlantic salmon (Salmo salar) to the Miramichi River (NB) for 1998 to 2009

By G. Chaput

Abstract

The assessment of Atlantic salmon (Salmo salar) returns and escapement to the Miramichi River (NB) for 2009 with updated values for 1998 to 2008 are presented. A hierarchical Bayesian mark and recapture model which considers multiple indicators including catches at estuary trapnets, counts at inriver monitoring facilities, and directed inriver seining programs is used to estimate the annual returns of small salmon (<63 cm fork length) and large salmon (>= 63 cm fork length). The return of small salmon in 2009 (at about 12,000 fish) was the lowest level since 1971. The large salmon return, of about 22,000 fish, was among the highest values since 1998. Harvest data of small salmon and large salmon from both the aboriginal fisheries and the recreational fisheries are incomplete. Overall for the Miramichi, total losses of eggs due to assumed losses from fishing have averaged 8% over both size groups, 5% for large salmon and 20% for small salmon. The eggs in the returns to the Miramichi in 2009 were 97% of the conservation requirement and the eggs which were estimated to have been spawned were 92% of the conservation requirement. The returns of salmon all size groups were sufficient to have met or exceeded the conservation requirements repeatedly between 1970 and 1996 but have only been sufficient to meet or exceed conservation twice during 1997 to 2009. At least 67% of the conservation requirements have been met every year since 1984. The most likely scenario in 2010 is for a low return of large salmon, in the order of 5,000 to 10,000 fish, or roughly 21% to 43% of the conservation requirement for the Miramichi overall. A number of recommendations for further analyses and model development are made.

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