Content uploaded by Patrice Brehmer
Author content
All content in this area was uploaded by Patrice Brehmer on Apr 09, 2018
Content may be subject to copyright.
BREHMER et al. (2015) ICAWA, WP2_S2_08
50
Session 02
First tridimensional pelagic fish school observation from scientific multibeam
echo sounder in Africa
Patrice BREHMER1,3,*, Yannick PERROT2, Abdoulaye SARRÉ3, Salahedine El AYOUBI4,
Mohamed TALEB5, Ebou Mass MBYE6, Jean-Pierre HERMAND7 and Xavier CAPET8
1Institut de Recherche pour le Développement (IRD), UMR 195 Lemar, BP1386, Dakar, Senegal
2Institut de Recherche pour le Développement (IRD), UMR 195 Lemar, Plouzané, France
3Institut Sénégalais de Recherches Agricoles (ISRA), Centre de Recherches Océanographiques de Dakar-
Thiaroye (CRODT), BP 2241, Dakar, Sénégal
4Institut National de Recherches Halieutiques (INRH), Bd Sidi Abderrahmane 2, 20180 Casablanca, Morocco
5Institut Mauritanien de Recherches Océanographiques et des Pêches (IMROP), BP 22, Nouadhibou, Mauritania
6Fisheries Department (FD), Ministry of Environment, Climate Change, Water, Wild Life and Fisheries, 7 Marina
Parade, Banjul, The Gambia
7Environmental Hydroacoustics Laboratory, Ecole Polytechnique, CP194/05, Université libre de Bruxelles (ULB),
B-1050 Bruxelles, Belgium
8Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanographie et du Climat:
Expérimentations et Approches Numériques (UMR Locean), Université Pierre et Marie Curie Paris, France
*Correspondance: Tél: (+221) 78 122 16 15; Courriel: Patrice.Brehmer@ird.fr (P. BREHMER)
Reçu le 13/10/2015; publié le 15/05/2016
AWA © MS WP2_S2_08
Abstract
Since the 70’s, numerous fisheries acoustics survey have been carry out in Africa,
particularly in West Africa and Morocco. Traditional echo sounder, single and
split beam, usually only detect a slide of the fish school occurring over the
continental shelf, due to their low depth or and wide size as well as the
avoidance reaction in front of a cursing vessel. The Simrad ME70 (70–120 kHz), is
a high resolution scientific multibeam echo sounder, characterized by calibrated
narrow beams and low sidelobe levels, which allow tridimensional rebuilt of an
entire fish school. Early trials were performed in the middle of 90’s using a Reson
Seabat 6012 multibeam sonar (455 kHz) in vertical beaming, in Senegal and Ivory
Coast. In this work, we present preliminary result obtain during the AWA cruise
off Senegal, Gambia and Mauritania. The upwelling during March 2014 was
strong and seldom school were observed in the beginning of the survey over
Mauritanian shelf, but cluster of large school were detected in Senegal. Using
dedicated software (movies3D) we have extracted fish school descriptors.
Consistency in fish school descriptors was validated between the Reson sonar
and Simrad SM 20 ones in previous study, and we assume that could also be the
case with ME70. Such hypothesis will allow comparing the change in Senegalese
fish school characteristics since early record in 1997-99. Such new scientific
multibeam systems (ME70) will allow new fishery research applications on
African small pelagic fish school and stocks for stock assessment and behavioral
studies.
1
a
2
Edited by:
Patrice BREHMER (IRD, France; Dakar), Babacar BA (CSRP, Sub-Region; Banjul) & Gerd
KRAUS (TI, Germany; Hamburg).
Technical support: Marie Madeleine GOMEZ (CSRP), Ndague DIOGOUL (IRD).
With the collaboration of:
Peter BRANDT, Bamol Ali SOW, Alban LAZAR, Xavier CAPET, Heino FOCK, Eric MACHU, Hamet
Diaw DIADIHOU, Didier JOUFFRE, Ibrahima DIALLO, Joern SCHMIDT, Werner EKAU, Amadou
GAYE, Mahfoudh ould TALEB SIDi, Modou THIAW, Cl Abdoulaye DIOP, Adama MBAYE,
Dienaba Beye TRAORE, Moussa SALL, Mariline DIARA, Assane FALL, Ibrahima LY, Ivanice
MONTEIRO, Vamara KONE, Aboubacar TOGUYENI, Marie BONNIN, Abdelmalek FARAJ.
ISBN: 978-2-9553602-0-2
Sub Regional Fisheries Commission / Commission Sous Régionale des Pêches ©2016
Cover design: AWA (BMBF – IRD) project
Logo and flyers: Laurent CORSINI (IRD)
Translation: Amadou NDIONE (independent)
Sponsors ICAWA 2015: