Recent stock recovery and potential future developments in the fishery, The rise management, of the assessment beaked and redfish population of Sebastes mentella in the Barents- and Norwegian Seas. Benjamin Planque Konstantin Drevetnyak Kjell Nedreaas
Life history characteristics Long-lived (75y) Late maturing (11y) Ovoviviparous Wide geographical distribution Large scale migrations Demersal & pelagic Spatialised demography
distribution and migration of S. mentella Mainly immature Mainly mature Nedreaas et al. (2011)
Historical development of the fishery 300 250 200 150 100 Outside EEZ Inside EEZ 50 0 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Landings in 1000 t
First signs of severe stock decline and the management actions taken Sharp decline in commercial catches until 1987 Similar stock decline confirmed by later assessments Huge discarded bycatch of S. mentella in the Barents Sea shrimp fisheries After increased fishery on new grounds 1986-1991 the recruitment finally fell severely from 1991 onwards Important to protect the last and reasonable good year-classes born before 1991 sorting grid mandatory in the shrimp fishery from 1993 onwards and more restrict bycatch rules and closure of areas Gradual implementation of closed areas and sorting grids in all trawl fisheries to protect spawning areas and undersized beaked redfish until all directed fisheries for S. mentella were banned in 2003.
Necessary measures and tools for monitoring the stock rebuilding and recovery Regularly surveys covering the different life stages over the distribution area of S. mentella Training of staff for correct identification of the different Sebastes species and age determination Development of a reliable analytical assessment model
Winter survey Summer ecosystem survey Russian autumn survey
Reconstructed recruitment from surveys only Planque et al. (2012)
0 group survey Slope surveys WGIDEEPS survey
% at age in Norwegian Sea surveys Year-class distribution density 0.00 0.02 0.04 0.06 0.08 0.10 pelagic 2008 pelagic 2009 pelagic 2013 Egga-sor 2009 Egga-sor 2012 Egga-nord 2011 Egga-nord 2013 1985-1990 Recruitment failure (1996-2003) 1940 1950 1960 1970 1980 1990 2000 2010 Year class
Assessment model 1. Schaefer Biomass dynamic model Input: total catches in biomass, survey(s) biomass index Output: total biomass time series Key assumption: fixed population growth rate
Biomass dynamic assessment: results The ratio of biomass in 2013 versus maximum biomass is 76%.
Biomass dynamic assessment: uncertainties 120 100 Depletion (B/K) 80 60 40 r=0.02 r=0.05 r=0.10 r=0.15 20 0 1960 1970 1980 1990 2000 2010 2020 Year
Assessment model 2. Statistical Catch At Age (SCAA) Statistical model Inputs: catch numbers@age, survey numbers@age, maturity@age, weight@age Output: time series of numbers and biomass@age in the population, fishing mortality Key assumptions: natural mortality rates, survey absolute estimates
SCAA assessment: uncertainties recruitment SSB Trends are robust Absolute levels are sensitive to assumptions
SCAA Assessment: results 1,400 Stock Biomass (tons) 1,200 SSB (tons) 1,000 800 600 400 200 0 900 800 700 600 500 400 300 200 100 0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Biomass (t) Thousands 2009 2010 2011 2012 2013 Numbers (millions) Rec (age 2) in millions
Management plan Based on recommendation by ICES, the Joint Norwegian-Russian Fisheries Commission (JNRFC) has agreed on the following management plan: An interim period with a low fixed TAC, until the strength of incoming strong year classes is confirmed. Following this transition period, the TAC will be set according to Ftarget of F0.1=0.039 Include a linearly reduction in F below a suggested SSB trigger point of 600 000 tonnes A minimum catch size of 30 cm A higher share of the catch to gender-balanced fisheries Measures currently in place to protect juveniles should be maintained A pronounced decrease of F if a series of weaker year classes is detected, as well as a Bstop different from zero, are considered sensible parts of a final management plan The management plan should be re-evaluated in 2017
Harvest Control Rules to meet the management plan ICES concludes that a fixed TAC of between 10 000 to 30 000 t would be compatible with the management objectives. Given that the next pelagic survey is expected to be in the autumn of 2016, ICES concludes that an annual fixed TAC within this range, and no more than 30 000 t, can be set for 2015, 2016, and 2017. This three-year TAC was adopted by the JNRF Commission. International agrement about the share of total TAC. The 44th Session of the Joint Norwegian-Russian Fisheries Commission decided to split the total TAC among countries, but the Northeast Atlantic Fisheries Commission (NEAFC) has not yet come to an agreement about the share of total TAC. Protection of juveniles, avoidance of beaked redfish less than 30 cm, and to conduct a gender-balanced fishery are achieved through strict bycatch regulations of the shrimp- and cod fisheries and to limit the directed redfish fishery to certain areas and seasons
The directed demersal and pelagic fisheries for S. mentella are limited to certain areas and seasons to meet the management plan Directed fishery only allowed in NEZ and international waters in the Norwegian Sea west of the green line (pelagic) and red line (demersal) 77 76 5 Tonnes/100km² 0-2 3-10 11-20 21-35 36-70 71-110 10 15 20 25 30 35 77 76 January-February: directed fishery only allowed west of the stipled red line due to undersized S. mentella south of Bear Island 75 74 73 75 74 73 1 March- 9 May: no directed fishery with demersal trawl is allowed due to larval extrusion and unequal gender composition 69 70 71 72 69 70 71 72 10 May- 31 December: directed fishery allowed west of the green line (pelagic) and solid red line (demersal) 68 67 66 5 10 15 20 25 0 100 200 400 nm 30 35 68 67 66 Catch of Sebastes Mentella in 2015 Selection: Directed and non-directed fisheries, all gears Area: NW: 1 3'15"E 77 51'9"N SE: 36 32'41"E 65 13'51"N Source: Directorate of Fisheries Statistics Department FMC Norway
66y of fisheries and management of S. mentella 1976: max. landings 269,000t 1985: demersal fishery targeting S. mentella south of 69 N 2003: min. landings 2,520t 2004: pelagic fishery in international waters 2014: directed fishery in Norwegian waters 1951 recruitment failure 1996 2003 2016 1951: description by V.I. Travin first year of international landing statistics 1993: sorting grids mandatory in the shrimp fishery 1997: sorting grids mandatory in all demersal fisheries 2003: directed fishery forbidden north of 62 N 2006: TAC set by NEAFC in Int. Waters 2014: TAC set to 30,000t for 3y + Management plan 2013: ICES advice for directed fishery
Summary / conclusion Very dynamic population, fisheries and management Crash in the 1980s followed by Recovery from 1990s to today, thanks to: Adaptive management measures that include, gear, season, area, TACs Continuous improvement in data collection and assessment, Management currently under a transition regime New management / HCRs / monitoring plan in place