Science Response 2012/019

Atlantic salmon fisheries scenario analysis for the Margaree River (NS) for 2012

Context

First Nations communities of Nova Scotia requested an increase in the food, social, and ceremonial (FSC) fishery allocations of small salmon and large salmon from the Margaree River for 2012 based on their aboriginal right to first access to fish for FSC purposes, after conservation requirements are met. In the most recent stock assessment of Atlantic salmon (Salmo salar) (DFO 2012), it was concluded that the returns and the spawning escapement of large salmon to the Margaree River, located in Salmon Fishing Area 18 of DFO Gulf Region, exceeded the conservation requirements every year since 1987. No forecasts of returns of either small salmon or large salmon to the Margaree River in 2012 were provided (DFO 2012).

To support the consultation process, DFO Gulf Fisheries and Aquaculture Management requested science advice on the risks to meeting conservation for Atlantic salmon of the Margaree River in 2012 for various Atlantic salmon fisheries scenarios for the Margaree River. Specifically, the request was for an increasing range of aboriginal peoples FSC allocations from the 2011 allocation level of 345 large salmon and 135 small salmon combined with recreational fishery management scenarios of:

1. recreational fisheries management measures as in 2011 (mandatory catch and release of large salmon (>= 63 cm fork length), season retention limit of 4 small salmon per licence, season June 1 to Oct. 31),
2. recreational fishery in October only and mandatory catch and release for small salmon and large salmon, and
3. no recreational fishery.

An estimate of the potential surplus to conservation requirements of large salmon in 2012, given the objective that there should be a low probability (< 5%) of failing to meet conservation, was also requested.

Given that the most recent stock assessment includes the 2011 return year (DFO 2012) and given the urgency of negotiating a harvesting plan for the First Nations FSC fisheries for 2012, a special science response process was initiated. This Science Response Report results from the Science Special Response Process of August 9, 2012 on the review of Atlantic salmon fisheries scenario analysis for the Margaree River (NS) for 2012. The advisory report was finalized on August 24 after a revised objective for small salmon was agreed and the model re-runs were completed as recommended during the initial review of August 9, 2012.

Based on the forecast of returns of large salmon to the Margaree River in 2012, a potential fishery harvest option of 917 large salmon would result in a low probability (5% or less) of failing to meet the conservation requirement. This harvest level represents an exploitation rate of 27.5% of the predicted large salmon return in 2012. The probability of meeting conservation declines from >99% to < 75% for increasing large salmon FSC harvest scenarios from 345 large salmon to 1,645 large salmon. At a similar exploitation rate of 27.5% on small salmon, a harvest option of 271 small salmon would be available for 2012.

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