@article{fdi:010040973,
  title = {{E}chotrace classification and spatial distribution of pelagic fish aggregations around drifting fish aggregating devices ({DFAD})},
  author = {{M}oreno, {G}. and {J}osse, {E}rwan and {B}rehmer, {P}atrice and {N}ottestad, {L}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}his work presents a method to observe pelagic fish around drifting fish aggregating devices ({DFAD}s). {A} triple-frequency vertical echosounder was employed to observe fish distributions in the vicinity of {DFAD}s. {S}urveys were conducted in a star pattern that was centred at the {DFAD}s. {T}he objective of the study was to define a methodology for future acoustic studies. {T}his goal was pursued by (i) studying the spatial distribution of fish aggregations, (ii) developing concepts for the grouping of observed aggregations and (iii) developing specifications for future autonomous acoustic tools. {F}or this purpose 5 cruises were carried out in the western {I}ndian {O}cean. {T}he multi-frequency approach proved useful as a means of separating acoustic detections into sound-scattering layers (e. g. plankton and micronekton), fish aggregations and individual fish. {F}ish target strength ({TS}) was measured. {F}our types of aggregations were found near {DFAD}s: ( i) dense structure (ii) medium structure (iii) loose structure and (iv) structure consisting of separated targets. {M}ore than 90% of these structures were found within a radius of 400 m and about 75% within 200 m of the {DFAD}s. {T}he spatial configuration of {DFAD} fish aggregations appeared to be more dynamic compared to aggregations near moored {FAD}s. {T}he spatial distribution and structure of {DFAD} aggregations have direct implications for their catchability by tuna purse-seiner. {W}e have carried out the first quantitative acoustic recordings around {DFAD}s, and obtained a better understanding of the spatiotemporal dynamics of fish aggregations around {DFAD}s in the {I}ndian {O}cean. {B}ased on this knowledge we are now working on specifications for instrumented buoys that are intended as autonomous data recording observatories for such pelagic environments.},
  keywords = {},
  booktitle = {},
  journal = {{A}quatic {L}iving {R}esources},
  volume = {20},
  numero = {4},
  pages = {343--356},
  ISSN = {0990-7440},
  year = {2007},
  DOI = {10.1051/alr:2008015},
  URL = {https://www.documentation.ird.fr/hor/fdi:010040973},
}