1 PELGAS : PELGAS : acoustic acoustic survey on the survey on - PDF document

French information on blue whiting : PELGAS : acoustic survey on the From Pelgas survey shelf From Evhoe survey 2000 From the fishery (self sampling) From discard sampling News from the Joseph Roty survey 1 2 PELGAS : PELGAS : acoustic acoustic survey on the survey on the shelf shelf 2002 2003 3 4 PELGAS : PELGAS : acoustic acoustic survey on the survey on the shelf shelf 2004 2005 5 6 1

PELGAS : PELGAS : acoustic acoustic survey on the survey on the shelf shelf 2006 2007 7 8 PELGAS : PELGAS : acoustic acoustic survey on the survey on the shelf shelf 2008 2009 9 10 EVHOE: groundfish survey (bottom trawl) (Bay of Biscay + Celtic Sea) since 1997 Blue whiting in Bay of Biscay & Celtic Sea PELGAS : Evhoe survey acoustic 2.0e+10 survey on the shelf 1.5e+10 2010 Abundance index (+ SD) 1.0e+10 5.0e+09 0.0e+00 1998 2000 2002 2004 2006 2008 2010 Year 11 12 2

EVHOE: groundfish survey (bottom trawl) EVHOE: groundfish survey (bottom trawl) (Bay of Biscay + Celtic Sea) since 1997 (Bay of Biscay + Celtic Sea) since 1997 Blue whiting <=20 cm in Bay of Biscay & Celtic Sea Blue whiting in Bay of Biscay Evhoe survey Evhoe survey 8e+09 2.0e+10 6e+09 1.5e+10 Abundance index (+ SD) Abundance index (+SD) 4e+09 1.0e+10 2e+09 5.0e+09 0e+00 0.0e+00 1990 1995 2000 2005 2010 1998 2000 2002 2004 2006 2008 2010 Year Year 13 14 EVHOE: groundfish survey (bottom trawl) 1997 1999 EVHOE: 1200 1200.00 1000 1000.00 (Bay of Biscay + Celtic Sea) since 1997 800 800.00 600 600.00 400 400.00 200 200.00 0 0.00 0 10 20 30 40 50 60 70 80 90 100 110 0 10 20 30 40 50 60 70 80 90 100 110 Blue whiting <=20 cm in Bay of Biscay Evhoe survey 1998 2000 1200 1200 8e+09 1000 1000 800 800 600 600 400 400 200 200 0 0 0 10 20 30 40 50 60 70 80 90 100 110 0 10 20 30 40 50 60 70 80 90 100 110 2001 2003 6e+09 1200 1200 1000 1000 800 800 600 600 400 400 200 200 Abundance index (+SD) 0 0 0 10 20 30 40 50 60 70 80 90 100 110 0 10 20 30 40 50 60 70 80 90 100 110 2002 2004 1200 1200 1000 1000 4e+09 800 800 600 600 400 400 200 200 0 0 0 10 20 30 40 50 60 70 80 90 100 110 0 10 20 30 40 50 60 70 80 90 100 110 2005 2008 1200 1200 1000 1000 2e+09 800 800 600 600 400 400 200 200 0 0 0 10 20 30 40 50 60 70 80 90 100 110 0 10 20 30 40 50 60 70 80 90 100 110 2006 2009 1400 1200 1200 1000 1000 800 800 600 600 0e+00 400 400 200 200 0 0 0 10 20 30 40 50 60 70 80 90 100 110 0 10 20 30 40 50 60 70 80 90 100 110 2007 2010 1200 1200 1990 1995 2000 2005 2010 1000 1000 800 800 600 600 400 400 200 200 Year 0 0 0 10 20 30 40 50 60 70 80 90 100 110 0 10 20 30 40 50 60 70 80 90 100 110 15 16 08/04/08-26/05/08 Self-sampling: since 2007 21/03/09-19/04/09 23/04/09-11/05/09 Self-sampling 16/03/10-17/04/10 Merlan bleu - Autoéchantillonnage 25% 2007 � 08/01/08-22/02/08 28/02/08-23/03/08 07/01/09-09/02/09 13/02/09-14/03/09 20% 05/01/10-07/02/10 11/02/10-10/03/10 2007-S fréquence 15% 2008-S 2009-S 2008-N 10% 09/10/07-11/11/07 2009-N 14/11/07-06/12/07 07/10/08-03/11/08 2010-N 08/11/08-25/11/08 28/09/09-3/11/09 5% 0% 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 taille (cm) 17 18 3

French catches: bigger sizes Some more information Blue whiting - ByCatch (discards) from the Nephrops fishery in the Bay of Biscay Merlan bleu - 2009 900 25. 800 IS 20. 700 FO 2007-3 600 ES fréquence (%) 2009-2 15. NOR-MIF 500 2009-3 NOR 2009-4 RU 400 2010-1 10. PT 300 2010-2 FR-Nord 2010-3 FR-Sud 200 5. NL 100 . 0 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 longueur (cm) length (cm) 19 20 Collaborative study between French fishing Sampling plan in 2011 company and Ifremer in 2011 Part 1) Normal fishing operation 17/1 – 11/2 and 26/2 – 16/3 Objectives of study between 52°North (Porcupine) and St-Kilda 57° 40 North North Investigate evidence for stock structure of blue whiting by Part 2) Survey type sampling Faroese � analysing spatial structure of 17/3 – 31/3 individual condition � analysing spatial structure of spawning fish with different South nursery areas during juvenile phase Scotland 21 22 Data collection First results: Cumulated length distribution Pelagic trawling 250 17/1 - 11/2/2011 - temperature on trawl Commercial 26/2 - 16/3/2011 - mean depth of trawling 17/3 - 31/3/2011 Survey - mean depth of sea floor 200 - duration of trawl haul - total catch (kg) 150 For 30 individuals per haul (randomly selected): Frequency - individual weight & length (lower 0.5 cm) - sex and maturity stage 100 - otoliths (10 individuals randomly selected Measurements during transects 50 - registration of acoustic echosounder signal (38 kHz, ER60) Laboratory analyses 0 - age from otoliths - otolith growth increments for juvenile phase 15 20 25 30 35 40 45 50 Length 23 24 4

First results: Acoustic school detection First results: Length-weight relationship Scale not compensated for roll and pitch! 25 26 Next steps - Contacts have been established to complement data with samples collected on scientific blue whiting survey - Age reading and growth increments for collected otolithes - Analysis of acoustic data to provide insight into spatial distribution of shoals - Statistical spatial analysis of weight-at-age and statistical spatial analysis of otolith growth increments in terms of evidence for stock structure 27 5