Updated Survey Indices for Silver and Red hake through 2019 - PowerPoint PPT Presentation

Updated Survey Indices for Silver and Red hake through 2019

Background • Relative index for the small mesh groundfish stocks are based on the seasonal NEFSC aggregate survey stratified catch weights • Following the accepted approach from SARC 51, a three year moving average is applied to the annual indices and used for stock status determination • Silver hake is based on the NEFSC fall survey biomass • Red hake is based on the NEFSC spring survey biomass • Survey indices for both red and silver hake were last updated in 2017 • Fall 2017: Reduced Survey coverage (No coverage in SNE and MA). • Missing strata in Fall 2018 – Imputed

NEFSC Survey Strata Map for Red and Silver hake Northern Strata: 20-30, 36-40 Missing strata in 2018 Str. 30 (3% stock Area) Southern Strata: 01-19, 61-76 Missing Strata in 2017 Str. 1-12 and 61-76 (75% stock Area)

Red hake: Last Assessment update (2017) > 3 times the threshold% above threshold 51% below threshold North South 7.0 2.00 3-yr. avg 3-yr Avg Spring 1.80 6.0 Target (2.53kg/tow) Survey Weight (Kg/tow) Survey 1.60 Threshold (1.27kg/tow) Target 5.0 Annual 1.40 (1.01kg/tow) 1.20 4.0 1.00 3.0 0.80 2.0 0.60 0.40 1.0 0.20 0.0 0.00 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 Year Year

Northern Red hake: Survey update through 2019 North 7.0 Annual - 43% Decline in 2019 6.0 3yr Avg. Fall Survey annual index from Target (2.53kg/tow) Survey Weight (Kg/tow) 5.3kg/tow to 5.0 Threshold (1.27kg/tow) 3.0kg/tow 4.0 - 3 Yr mean continues to decline. From 5.1 3.0 kg/tow to 4.3 kg/tow 2.0 - Remains above target and threshold 1.0 0.0 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 Year

Northern Red hake: Size Composition 2010-2019 - Average and below average recruitment from 2016-2018 explains the 2019 decline - Above average 2019 year class. Recruitment (3-20cm) 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Mean 3-21cm 1.81 0.84 1.04 3.40 10.56 1.59 3.06 2.43 2.03 3.50 3.02 % from Prev Yr -53% 23% 228% 210% -85% 93% -21% -16% 73%

Southern Red hake: Survey update through 2019 South 2.00 Annual 1.80 3 yr Avg. Spring Survey 1.60 Target (1.01kg/tow) - Three year average 1.40 increased by 41% form Threshold (0.51kg/tow) Survey Weight (Kg/tow) 0.27kg/to 0.38kg/tow 1.20 1.00 - Stock biomass remains below the threshold 0.80 0.60 0.40 0.20 0.00 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 Year

Southern Red hake: Size Composition 2010-2019 - Above average recruitment in 2019 Recruitment (1-20cm) 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Mean 1-21 cm 1.65 0.46 1.56 0.39 0.79 0.36 0.69 0.39 0.64 2.35 0.93 % from Prev Yr -72% 241% -75% 103% -55% 91% -44% 67% 265%

Red hake • Three year mean of the spring survey continues to decline in the north but still well above the target and threshold • In the south, the 3 yr average increased in 2019, owing to the above average incoming year class. However the stock still remains below the threshold. • There appears to be an above average incoming year class in 2019 in both the North and South.

Silver hake – Last survey update (2017) North South 25 3.0 Annual 3 yr Avg. fFall survey 3 yr Avg. fFall survey Target (1.65 kg/tow) 20 Target (6.42 kg/tow) Survey Weight (Kg/tow) Threshold (0.825 kg/tow) Threshold (3.21 kg/tow) 2.0 Annual 15 10 1.0 5 0 0.0 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Year Year

Northern Silver Hake – Stratum 30 • In Fall of 2018, the survey did not cover stratum 30 • Applied the Ratio approach to develop a raising factor to impute missing stratum 30 • Raising factor was based on the Bigelow fall survey for years 2009-2017 • Stratum 30 only constitute of 3% of the total stock Area (NE Geo.Bank) • Time Series average contribution of Stratum 30 by weight ~3% • Imputation had miniscule effect

Northern Silver Hake – Relative Contribution of Stratum 30 Fall Survey 1.6 (Expanded catch in weight All Strata)/(Expanded Catch in Weight w/out Stratum 30) 1.4 Ratio [(All Strata)/(All strata-Str30)] 1.2 1.0 0.8 0.6 0.4 0.2 0.0 1963 1967 1971 1975 1979 1983 1987 1991 1995 1999 2003 2007 2011 2015

Northern Silver hake Heterogeniety in the pattern of biomass vs. "contribution" from Stratum 30 1.30 1967 1969 1.25 Ratio [(All Strata)/(All strata-Str30)] 1.20 1976 1996 1968 2014 1.15 1.10 1.05 1.00 0.95 0.90 0.0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 13.5 15.0 16.5 18.0 19.5 21.0 22.5 24.0 25.5 Biomass (weight /tow) Does stratum 30 depend on biomass. i.e. increase or decrease at low or high stock? No Strong pattern

Northern Silver hake Fall Survey Expanded Catch in Weight 600,000 Expanded Catch Weights (kg) 500,000 Stratum 30 All Strata W/out Stratum 30 400,000 300,000 200,000 100,000 0 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 2017 1963 – 2017 : TS average contribution of stratum 30 ~ 3% 2009 – 2017: also ~ 3%

Northern Silver hake: Survey update through 2019 25 Annual 38% decline in the 3 yr Avg. Fall Survey survey biomass 20 Target (6.42 kg/tow) since 2016 from Threshold (3.21 kg/tow) Survey Weight (Kg/tow) 21.5kg/tow to 15 2018_adj. 13.25kg/tow Three year mean 10 also has declined in the recent three 5 years but is still 5 times above the thresholds 0 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 Year Year kg/tow Imputing is inconsequential for the 2018_unad 13.25 northern stock. 2018_adj 13.15

Northern Silver hake: Size Composition 2009-2018 Above recruitment average in 2016-2017. Recruitment (1-20cm) 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 Mean 1-20cm 60.31 51.26 44.18 61.92 65.08 53.36 70.61 61.86 82.93 87.55 63.91 % from Prev Yr -15% -14% 40% 5% -18% 32% -12% 34% 6%

Southern Silver Hake – Fall 2017 • No Coverage in SNE and MA region • Seven of 35 survey strata was covered and only in the S.Geo.Bank region • Missing strata 1-12 and 61-76 constitute 75% of the total Mgt. Area • On average (1967-2016), these missing strata contribute to 72% of total catch for the Mgt. area • Imputation of fall survey 2017 value is likely going to be unreliable owing to a significant fraction of missing strata from the Mgt. Area. • An alternative approach is to treat fall survey 2017 as a missing value

Southern Silver hake Relative Contribution of Strata 1-12 & 61-76 Fall Survey 14.0 (Expanded catch in weight All Strata)/ Ratio [(All Strata)/(All strata - Missing strata)] (Expanded Catch in Weight w/out Missing Strata:1-12 and 61-76.) 12.0 10.0 8.0 6.0 4.0 2.0 0.0 1967 1971 1975 1979 1983 1987 1991 1995 1999 2003 2007 2011 2015

Southern Silver hake Heterogeniety in pattern of biomass vs. "contribution" from Missing strata (1-12, 61-76) 14.00 12.00 1985 Ratio [(All Strata)/(All strata-Str30)] 10.00 1979 1999 8.00 6.00 2010 2016 4.00 2012 2014 2009 2011 2013 2.00 2015 0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Southern Silver hake Fall Survey Expanded Catch in Weight 140,000 Missing Strata 1-12 and 61-76 120,000 On average missing All Strata W/out Mising Strata strata constitute 65- 100,000 Expanded Catch Weights (kg) 72% by weight. 80,000 60,000 40,000 20,000 0 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015

Southern Silver hake All Strata vs All Strata Excl. Missing Strata 140,000.00 y = 0.7876x + 45346 120,000.00 Expanded Catch Wts 1967-2016 R² = 0.0534 100,000.00 80,000.00 All Strata 60,000.00 40,000.00 20,000.00 0.00 0.0 5000.0 10000.0 15000.0 20000.0 25000.0 30000.0 35000.0 All Strata-Missing Strata

Southern Silver hake All Strata vs All Strata Excl. Missing Strata 120,000.00 100,000.00 Expanded Catch wts y = 3.1513x - 1054.5 R² = 0.4318 2009-2016 80,000.00 All Strata 60,000.00 40,000.00 20,000.00 0.00 0.0 5000.0 10000.0 15000.0 20000.0 25000.0 30000.0 All Strata-Missing Strata

Southern Silver hake: Survey update through 2018 3.0 Annual 3 yr average Fall biomass Target (1.65 kg/tow) Threshold (0.825 kg/tow) Ratio - 3yr avg 2.0 Survey Weight (Kg/tow) Regression - 3yr avg. 1.0 0.0 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 Year

Southern Silver hake: Size Composition 2009-2018