PMID- 32056700 OWN - NLM STAT- MEDLINE DCOM- 20200624 LR - 20200624 IS - 1879-0291 (Electronic) IS - 0141-1136 (Linking) VI - 154 DP - 2020 Feb TI - Multi-frequency and light-avoiding characteristics of deep acoustic layers in the North Atlantic. PG - 104842 LID - S0141-1136(19)30462-3 [pii] LID - 10.1016/j.marenvres.2019.104842 [doi] AB - This study aimed to add light-avoidance as a categorizing technique for the study of mesopelagic acoustic layers. Data recorded along the 20 degrees W parallel from 20 degrees N to Iceland showed three types of mesopelagic layers: the non-avoiding non-migrant deep scattering layer (NMDSL), which dropped its intensity toward the north, the avoiding migrating fish layers (MDSL), which were more intense at upwelling areas and toward the north, and a secondary deeper NMDSL at the southern part. Light avoidance was only discernible at 18 kHz within the main NMDSL when this layer was intense, suggesting that migrants are barely seen at 38 kHz when other resonant scatterers occupy these depths. These results highlight the importance of employing the 18 kHz frequency from a vessel borne echosounder or lowered echosounders attached to a probe to study gas-bearing migrants. CI - Copyright (c) 2019 Elsevier Ltd. All rights reserved. FAU - Pena, Marian AU - Pena M AD - Instituto Espanol de Oceanografia (IEO), Centre Oceanografic de Balears, Muelle de Poniente s/n, Palma, Spain. Electronic address: marian.pena@ieo.es. FAU - Cabrera-Gamez, Jorge AU - Cabrera-Gamez J AD - Instituto de Sistemas Inteligentes y, Aplicaciones Numericas en Ingenieria, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain. FAU - Dominguez-Brito, Antonio C AU - Dominguez-Brito AC AD - Instituto de Sistemas Inteligentes y, Aplicaciones Numericas en Ingenieria, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain. LA - eng PT - Journal Article DEP - 20191202 PL - England TA - Mar Environ Res JT - Marine environmental research JID - 9882895 SB - IM MH - *Acoustics MH - Animals MH - Atlantic Ocean MH - *Fishes MH - Iceland MH - Light MH - *Seawater/chemistry MH - Water Movements OTO - NOTNLM OT - Artificial light OT - Avoidance OT - Deep scattering layers OT - Frequency response OT - Mesopelagic OT - Migration COIS- Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. EDAT- 2020/02/15 06:00 MHDA- 2020/06/25 06:00 CRDT- 2020/02/15 06:00 PHST- 2019/07/18 00:00 [received] PHST- 2019/11/04 00:00 [revised] PHST- 2019/11/20 00:00 [accepted] PHST- 2020/02/15 06:00 [entrez] PHST- 2020/02/15 06:00 [pubmed] PHST- 2020/06/25 06:00 [medline] AID - S0141-1136(19)30462-3 [pii] AID - 10.1016/j.marenvres.2019.104842 [doi] PST - ppublish SO - Mar Environ Res. 2020 Feb;154:104842. doi: 10.1016/j.marenvres.2019.104842. Epub 2019 Dec 2.