Assessment of redfish in the Northwest Atlantic Fisheries Organization (NAFO) subarea 0, October 2016

Abstract

This is the first assessment of redfish in Northwest Atlantic Fisheries Organization (NAFO) Subarea (SA) 0 (Divisions 0A and 0B). Biomass estimates for Deepwater Redfish (Sebastes mentella) from Fisheries and Oceans Canada (DFO) surveys in NAFO Division 0B (400 to 1500 m) during 2011 to 2015 have been in the range of 20,000 to 43,000 t. This is an increase from estimates of 6,800 t in 2000 and 13,600 t in 2001. The Eastern Assessment Zone survey index for redfish spp. (primarily S. mentella) from the Northern Shrimp Research Foundation survey has been relatively stable between 100,000 and 150,000 t, with a peak in 2010 of about 336,000 t. An index of recruitment is not available, peaks in abundance in the Division 0B survey can be followed from 17 to 25 cm between 2011 and 2015. The proportion of Deepwater Redfish greater than 20 cm also increased from < 40% in 2000 and 2001 to > 80% during 2013–2015. Redfish in SA 0 are not commercially harvested. Fishing mortality is limited to bycatch, mainly of juvenile fish caught in shrimp fisheries, and to a lesser extent in Greenland Halibut (Reinhardtius hippoglossoides) fisheries. Bycatch totals rarely exceeded 200 t during 1997 to 2012. The peer-review meeting was not able to validate or invalidate existing limit reference points (LRPs) for the Northern Population of Deepwater Redfish (SA 0+2+3KLNO) derived from production models in 2012, due to substantive concerns about input data and incomplete documentation of the rationale for model formulation. In the absence of an LRP, it is not possible to identify what zone of the Precautionary Approach Framework the SA 0 Deepwater Redfish stock is currently within. Despite a gap in the time series, the Division 0B survey indicates an increase in biomass from the first two surveys conducted in 2000 and 2001 to more recent surveys during 2011 to 2015. Also, the Eastern Assessment Zone survey has been relatively stable during 2005 to 2012, except for a very high value in 2010. These survey indices, suggest recent levels of bycatch in SA 0 are not limiting stock development. Any requests to conduct exploratory fisheries for redfish in NAFO SA 0 should be considered with caution and proceed only with robust programs in place for monitoring and scientific data collection. Stock indices need to be closely monitored throughout any exploratory fishing. The minimum mesh size used should not be smaller than is allowed in other Canadian jurisdictions.