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Institute of

OF Baltic Sea Fisheries

Dr. Juan Santos

Institute of Baltic Sea Fisheries

Alter Hafen Süd 2
18069 Rostock
+49 381 66099 122
+49 381 66099 199

Fields of activity

  • Bycatch reduction in active and passive fisheries
  • Development and testing of fishing gear technologies to address species and size selectivity in mixed fisheries
  • Sampling scheme planning and cruise leadership in experimental sea trials
  • Quantitative and qualitative assessment of species/size selection and relative catchability of fishing gears


Contact Person for

  • SFI Biodegradable plastics for use in fisheries

Involved in

ongoing projects

completed projects

Research interests

Fishing gears, trawl hydrodynamics and efficiency, trawl size selection, species selection in mixed fisheries, bycatch, fishing discards, fish behaviour, sampling design, programming, computer simulation, statistics (parametric and non-parametric regression tools, Mixed modelling, non-parametric inference tools [bootstrapping, jackknife, cross-validation and others], multivariate analysis)

Scientific background

Since Jan. 2013: Senior Researcher at the Thuenen Institute of Baltic Sea Fisheries, Rostock, Germany

2009 - 2012: Instituto Espanol de Oceanografıa, Vigo, Spain, Research technician (UE (DCR)-IEO)

  • Monitoring the behavior of Spanish fisheries operating in ICES areas in relation with future by-catch and discards EU policy
  • Selective gear design for by-catch reduction in ICES areas
  • Selectivity projects management and monitoring. Data analysis
  • Dissemination of effects of discard reduction technical measures tofishers
  • Keep track of the laws and rules applicable to Spanish fisheries in ICESareas, and coordination with European researchers in the task of applytechnical measures for by-catch reduction
  • Preparation and presentation of discards data from ICES fleets for demandinginstitutions
  • Participation in research surveys related with DCF

Sep. 2007: M.S.Marine Biology and Aquaculture, Universidade de Santiago de Compostela,Santiago de Compostela, Spain. Thesis Topic: A comparison of two methods for discards estimation incommercial fishing vessels. Adviser:Professor Manuel Aldegunde.

Oct. 2006 - Feb. 2007: Selectivity project RAI-AP-10/2006

Jul. 2006 - Oct. 2006: Spanish Discard Sampling Programme

Oct. 2005 - Mar. 2006: Selectivity project RAI-AP-21/2005

Nov. 2004 - Sep. 2005: Spanish Discard Sampling Programme

Jun. 2004 to Nov. 2005: Spanish Pelagic Longline Sampling Programme

Dec. 2002: Degree in Biology Science


  1. 0

    Sistiaga M, Herrmann B, Brinkhof J, Larsen RB, Santos J, Stepputtis D, Brinkhof I, Jacques N, Cerbule K, Petetta A, Cuende E, Kvalvik L (2023) Is there a limit to the potential effects of shortening lastridge ropes on the size selectivity of diamond mesh codends? Fish Res 262:106671, DOI:10.1016/j.fishres.2023.106671

  2. 1

    Kratzer I, Stepputtis D, Santos J, Lütkefedder F, Stoltenberg A, Hartkens L, Schaber M, Kindt-Larsen L, Larsen F (2022) Angle-dependent acoustic reflectivity of gillnets and their modifications to reduce bycatch of odontocetes using sonar imaging. Fish Res 250:106278, DOI:10.1016/j.fishres.2022.106278

  3. 2

    Bak-Jensen Z, Herrmann B, Santos J, Jacques N, Melli V, Feekings JP (2022) Fixed mesh shape reduces variability in codend size selection. Can J Fish Aquat Sci 79(11):1820-1829, DOI:10.1139/cjfas-2022-0049

  4. 3

    Brooks ME, Melli V, Savina E, Santos J, Millar R, O'Neill FG, Veiga-Malta T, Ahm Krag L, Feekings JP (2022) Introducing selfisher: open source software for statistical analyses of fishing gear selectivity. Can J Fish Aquat Sci 79(8):1189-1197, DOI:10.1139/cjfas-2021-0099

  5. 4

    Santos J, Stepputtis D, Oesterwind D, Herrmann B, Lichtenstein U, Hammerl C, Krumme U (2022) Reducing cod bycatch in flatfish fisheries. Ocean Coastal Manag 220:106058, DOI:10.1016/j.ocecoaman.2022.106058

  6. 5

    Stepputtis D, Noack T, Lichtenstein U, Hammerl C, Santos J, Mieske B (2022) Verringerungen von Kunststoffmüll aus der Krabbenfischerei durch Netzmodifikationen - Dolly Rope Suspension (DRopS) : Projekt-Abschlussbericht. Braunschweig: Johann Heinrich von Thünen-Institut, 180 p, Thünen Rep 101, DOI:10.3220/REP1670832160000

  7. 6

    Chladek J-C, Stepputtis D, Hermann A, Ljungberg P, Rodriguez-Tress P, Santos J, Svendsen JC (2021) Development and testing of fish-retention devices for pots: transparent triggers significantly increase catch efficiency for Atlantic cod (Gadus morhua). ICES J Mar Sci 78(1):199-219, DOI:10.1093/icesjms/fsaa214

  8. 7

    Polte P, Gröhsler T, Kotterba P, Nordheim L von, Moll D, Santos J, Rodriguez-Tress P, Zablotski Y, Zimmermann C (2021) Reduced reproductive success of Western Baltic herring (Clupea harengus) as a response to warming winters. Front Mar Sci 8:589242, DOI:10.3389/fmars.2021.589242

  9. 8

    Günther C, Temming A, Santos J, Berkenhagen J, Stepputtis D, Schultz S, Neudecker T, Kraus G, Bethke E, Hufnagl M (2021) Small steps high leaps: Bio-economical effects of changing codend mesh size in the North Sea Brown shrimp fishery. Fish Res 234:105797, DOI:10.1016/j.fishres.2020.105797

  10. 9

    Chladek J-C, Stepputtis D, Hermann A, Kratzer I, Ljungberg P, Rodriguez-Tress P, Santos J, Svendsen JC (2021) Using an innovative net-pen-based observation method to assess and compare fish pot-entrance catch efficiency for Atlantic cod (Gadus morhua). Fish Res 236:105851, DOI:10.1016/j.fishres.2020.105851

  11. 10

    Stepputtis D, Santos J, Mieske B, Lichtenstein U, Schütz A, Stechert R (2020) Abschlussbericht an das Ministerium für Landwirtschaft und Umwelt Mecklenburg-Vorpommern für das Projekt CODEX (CodExcluder) - Netzmodifikation zur Reduktion des Dorschbeifanges. Rostock: Thünen Institute of Baltic Sea Fisheries, 99 p

  12. 11

    Herrmann B, Sistiaga M, Larsen RB, Brinkhof J, Gjøsund SH, Jacques N, Santos J (2020) Catch pattern and size selectivity for a gear designed to prevent fish injuries during the capture process in a North-East Atlantic demersal trawl fishery. Reg Studies Mar Sci 40:101525, DOI:10.1016/j.rsma.2020.101525

  13. 12

    Sistiaga M, Herrmann B, Brinkhof J, Larsen RB, Jacques N, Santos J, Gjøsund SH (2020) Quantification of gear inflicted damages on trawl-caught haddock in the Northeast Atlantic fishery. Mar Pollut Bull 157:111366, DOI:10.1016/j.marpolbul.2020.111366

  14. 13

    Santos J, Herrmann B, Stepputtis D, Kraak SBM, Gökce G, Mieske B (2020) Quantifying the performance of selective devices by combining analysis of catch data and fish behaviour observations: methodology and case study on a flatfish excluder. ICES J Mar Sci 77(7-8):2840-2856, DOI:10.1093/icesjms/fsaa155

  15. 14

    Stepputtis D, Santos J, Zimmermann C (2020) Technical approaches to avoid cod catches in Baltic Sea trawl fisheries : A report for the BALTFISH high level group. Rostock: Thünen Institute of Baltic Sea Fisheries, 37 p

  16. 15

    Eero M, Carlshamre S, Stepputtis D, Krumme U, Maioli F, Prista N, Schade FM, Santos J, Noack T, Valentinsson D, Nilsson H, Feekings JP, Storr-Paulsen M, Plikshs M, Bergström U, Hakansson KB, Radtke K (2019) Report on eastern baltic cod bycatch in non-targeted fisheries, mixing with western baltic cod in SD24, and stock situation in SDS 27-32. Copenhagen: ICES, 69 p, ICES Sci Rep 1(76), DOI:10.17895/

  17. 16

    Larsen RB, Sistiaga M, Herrmann B, Brinkhof J, Tatone I, Santos J (2019) The effect of Nordmøre grid length and angle on codend entry of bycatch fish species and shrimp catches. Can J Fish Aquat Sci 76(2):308-319, DOI:10.1139/cjfas-2018-0069

  18. 17

    Kraak SBM, Haase S, Minto C, Santos J (2019) The Rosa Lee phenomenon and its consequences for fisheries advice on changes in fishing mortality or gear selectivity. ICES J Mar Sci 76(7):2179-2192, DOI:10.1093/icesjms/fsz107

  19. 18

    Larsen RB, Herrmann B, Sistiaga M, Brinkhof J, Santos J (2018) Catch and release patterns for target and bycatch species in the Northeast Atlantic deep-water shrimp fishery: Effect of using a sieve panel and a Nordmøre grid. PLoS One 13(12):e0209621, DOI:10.1371/journal.pone.0209621

  20. 19

    Yulianto I, Booth H, Ningtias P, Kartaqijaya T, Santos J, Sarmintohadi, Kleinertz S, Campbell SJ, Palm HW, Hammer C (2018) Practical measures for sustainable shark fisheries: Lessons learned from an Indonesian targeted shark fishery. PLoS One 13(11):e0206437, DOI:10.1371/journal.pone.0206437

  21. 20

    Santos J, Herrmann B, Stepputtis D, Günther C, Limmer B, Mieske B, Schultz S, Neudecker T, Temming A, Hufnagl M, Bethke E, Kraus G (2018) Predictive framework for codend size selection of brown shrimp (Crangon crangon) in the North Sea beam-trawl fishery. PLoS One 13(7):e0200464, DOI:10.1371/journal.pone.0200464

  22. 21

    Santos J, Herrmann B, Mieske B, Krag LA, Haase S, Stepputtis D (2018) The efficiency of sieve-panels for bycatch separation in Nephrops trawls. Fish Manag Ecol 25(6):464-473, DOI:10.1111/fme.12323

  23. 22

    Santos J (2017) Bericht über die 725. Reise des FFS Solea vom 07.09 bis 23.09.2016 : Fahrtleitung: Juan Santos. Rostock: Thünen-Institut für Ostseefischerei, 44 p

  24. 23

    Santos J, Stepputtis D (2017) Report of the Cruise N 739, by the FRV Solea from 12:09 to 28:09:2017 Cruise leaders Juan Santos & Dr. Daniel Stepputtis. Rostock: Thünen-Institut für Ostseefischerei, 26 p

  25. 24

    Alonso-Fernandez A, Otero J,, Banon R, Compelos JM, Santos J, Mucientes G (2017) Sex ratio variation in an exploited population of common octopus: ontogenic shifts and spatio-temporal dynamics. Hydrobiologia 794(1):1-16, DOI:10.1007/s10750-016-3065-3

  26. 25

    Santos J (2016) Bericht über die 709. Reise des FFS Solea vom 09.09 bis 26.09.2015 : Fahrtleitung: Juan Santos. Rostock: Thünen-Institut für Ostseefischerei, 16 p

  27. 26

    Stepputtis D, Santos J, Herrmann B, Mieske B (2016) Broadening the horizon of size selectivity in trawl gears. Fish Res 184:18-25, DOI:10.1016/j.fishres.2015.08.030

  28. 27

    Santos J, Mieske B, Stepputtis D, Krag LA, Herrmann B (2016) Development and testing of HESPAN, a sievenet-based BRD for nephrops trawl fisheries : Bericht über die 709. Reise des FFS Solea vom 09.09. bis 25.09.2015. Rostock: Thünen-Institut für Ostseefischerei, 18 p

  29. 28

    Santos J (2016) El pez plano que utilizó la ventana y se largó. Pesca Internacional 17(175):35-37

  30. 29

    Herrmann B, Sistiaga M, Santos J, Sala A (2016) How many fish need to be measured to effectively evaluate trawl selectivity? PLoS One 11(8):e0161512, DOI:10.1371/journal.pone.0161512

  31. 30

    Haase S, Santos J (2016) Jovenes y ancianos primero : Puesta en práctica de un nuevo concepto de selectividad para la pesca de arrastre. Pesca Internacional(11):16-20

  32. 31

    Santos J, Herrmann B, Mieske B, Stepputtis D, Krumme U, Nilsson H (2016) Reducing flatfish bycatch in roundfish fisheries. Fish Res 184:64-73, DOI:10.1016/j.fishres.2015.08.025

  33. 32

    Santos J, Herrmann B, Otero P, Fernandez J, Perez N (2016) Square mesh panels in demersal trawls: does lateral positioning enhance fish contact probability? Aquatic Liv Res 29(3):1-10, DOI:10.1051/alr/2016025

  34. 33

    Santos J, Mieske B, Stepputtis D (2016) Testing FLEX, a FLatfish EXcluder device for trawl fisheries : Bericht über die 696. Reise des FFS Solea vom 12.11. bis 21.11.2014. Rostock: Thünen-Institut für Ostseefischerei, 16 p

  35. 34

    Schultz S, Günther C, Santos J, Berkenhagen J, Bethke E, Hufnagl M, Kraus G, Limmer B, Stepputtis D, Temming A, Neudecker T (2015) Optimierte Netz-Steerte für eine ökologisch und ökonomisch nachhaltige Garnelenfischerei in der Nordsee (CRANNET) : Projektabschlussbericht. Hamburg; Rostock: Johann Heinrich von Thünen-Institut; Universität Hamburg, Institut für Hydrobiologie und Fischereiwissenschaften, 374 p

  36. 35

    Zimmermann C, Kraak SBM, Krumme U, Santos J, Stötera S, Nordheim L von (2015) Research for PECH Committee - Options of handling choke species in the view of the EU Landing Obligation – The Baltic plaice example : study. Brussels: European Union, 100 p, DOI:10.2861/808965

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