Science Response 2012/020
Effect of 2008 ice entrapment on the Eclipse Sound narwhal total allowable landed catch
Context
In late 2008, an extreme mortality event occurred in the Eclipse Sound area of Baffin Island, Nunavut when more than 629 narwhals were trapped in ice (a “Footnote 1savssat”). Prior to this event, the Nunavut Wildlife Management Board had asked Fisheries and Oceans Canada (DFO) to provide science advice on sustainable levels of harvest for all narwhals and beluga stocks in Nunavut. This advice was provided (DFO 2008) and the current analysis assesses the possible impact of the extreme mortality event on the recommended harvest levels for the Eclipse Sound narwhal stock.
Modelling was used to determine sustainable harvest levels by varying the magnitude of the mortality event over that which could be assumed to be natural mortality. A meeting was held 23 September 2009 by teleconference to review the results of the modelling and provide advice on the impact of the extreme mortality event.
Model results indicate that, even if the entrapment event had caused mortality levels greater than the expected level of natural mortality, the harvest levels need only be reduced by 13 or fewer narwhals to be sustainable. However, if entrapment events of this magnitude were to become more common, the sustainable harvest levels would need to be further revised.
This Science Response Report results from the Science Special Response Process of September 23, 2009 on the effect of ice entrapment on the recommendation for Eclipse Sound Narwhal total allowable harvest.
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