An assessment of beaked redfish (S. mentella and S. fasciatus) in NAFO division Div. 3M

• Main Authors: Ávila de Melo, A., Alpoim, R., Saborido-Rey, Fran
• Format: Article in Journal/Newspaper
• Language: English
• Published: Northwest Atlantic Fisheries Organization 2003
• Subjects: Sebastes mentella
• Online Access: http://hdl.handle.net/10261/48485

72 páginas, 19 tablas, 17 figuras.-- Scientific Council Meeting The present assessment evaluates the status of the Div. 3M beaked redfish stock, regarded as a management unit composed of two populations from two very similar species (Sebastes mentella and Sebastes fasciatus). The sum of the absolute length compositions of the 1989-2002 commercial catch with the 1993-2002 by-catch is the Div. 3M redfish catch at length input of this assessment. The VPA assessment used a 1989-2002 catch at age matrix starting at age 4 and having a plus group at age 19. An Extended Survivor Analysis (Shepherd, 1999) was performed using the previous XSA framework. The consistency of the XSA results was checked with a Retrospective Analysis confined to the assessments of the most recent years, 2002-2000. A logistic surplus production model (ASPIC) which does not use the equilibrium assumption (Praguer, 1994 and 1995) was also applied using the 1959-2002 catch coupled with the STATLANT standardised CPUE series (1959-1993) and the age 4 plus EU bottom biomass (1988-2002). The ASPIC results, as regards biomass and fishing mortality trends are comparable to the ones from the XSA but with biomass declining to a lesser extent and increasing at faster rate from 1998 onwards. Either XSA or ASPIC analysis pointed out that the Div. 3M beaked redfish stock experienced a steep decline from the second half of the eighties till 1996. Fishing mortality was kept well above Fmsy over the first half of the assessment period. From 1995 onwards fishing mortality dropped and since 1997 has been kept well below the assumed natural mortality. Despite recent fluctuations biomass and female spawning biomass are generally increasing since 1997 but at slow rates, being still well bellow the levels of the first years of the time series. The stock reproductive potential has increased through the nineties compensating the SSB decline and sustaining a 1998-2002 geo-mean recruitment at age 4 identical to the former years of 1989-1993. The 1998 year-class at age ...