An Assessment of Beaked Redfish (S. mentella and S. fasciatus) in NAFO Division 3M (at times when natural mortality is driven stock dynamics and fishing mortality reference points are useless to scientific advice)

Abstract

The 3M redfish assessment is focused on the beaked redfish, regarded as a management unit composed of two populations from two very similar species: the Flemish Cap S. mentella and S. fasciatus. The reason for this approach is the historical dominance of this group in the 3M redfish commercial catch until 2005. However a new golden redfish fishery (S. marinus) started on September 2005 on shallower depths of the Flemish Cap bank above 300m, and the Flemish Cap cod fishery reopened in 2010. These new realities implied a revision of catch estimates, in order to split recent redfish commercial catch and by-catch from the major fleets on Div. 3M into golden (S. marinus) and beaked (S. mentella and S. fasciatus) redfish catches. The Extended Survivor Analysis assessment used as tuning file the 1989-2014 EU survey abundance at age matrix included in a revised input framework. Continuing pressure over Flemish Cap redfish stocks by cod predation, at levels higher, or much higher, than the levels prior to 2006 lead to higher natural mortalities since then. Natural mortality have been tuned to survey at age data 2006 onwards by the sensitivity analysis preceding each assessment, and on 2013-2104 has a best estimate at slightly higher level from previous years. A 2015-2011 retrospective XSA was carried out, confirming that the present assessment is very much in line with their immediate predecessors.