caa a22 4500 397551630 CHVBK 20180308164752.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.1006/jmsc.1996.0062 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0062 Acoustic evidence for unusual diel behaviour of a mesopelagic fish (Vinciguerria nimbaria) exploited by tuna [Elektronische Daten] [Emile Marchal, Anne Lebourges] For 15 years, there has been a seasonal tuna fishery in the open equatorial Atlantic Ocean. There are no good reasons for explaining this concentration of fish, except the possible abundance of micronekton. However, micronekton are only found during the night in the upper layers, whereas tuna feed during the day, according to current assumptions. An acoustic cruise carried out in November 1992 clearly showed the presence in this area of a large schooling biomass of a small mesopelagic fish, Vinciguerria nimbaria (Photichtyidae). Instead of diving to a great depth during the day as usual, they remained in the upper layers and tuna (Katsuwonus pelamis and Thunnus albacares) were found to feed on them. The atypical behaviour of Vinciguerria involved two processes: reverse phototaxis and a break in the diel vertical migrations. A review of the literature shows that this fish: (1) is a common item in tuna stomach contents; and (2) is never caught in the upper layers during the day. This apparent discrepancy has been resolved by our results: schooling behaviour during the day prevents Vinciguerria from being sampled adequately by the usual systematic net tows. The need to use acoustics for successful sampling is obvious. It is likely that this behaviour occurs in other areas and could explain the local concentration of tuna. © 1996 International Council for the Exploration of the Sea Regular Articles nationallicence acoustics nationallicence diel behaviour nationallicence Katsuwonus pelamis nationallicence Thunnus albacares nationallicence tuna feeding nationallicence Vinciguerria nationallicence Marchal Emile ORSTOM, Institut Océanographique 195 rue Saint Jacques, F75005 Paris, France aut Lebourges Anne Centre ORSTOM de Brest BP 70, F29280 Plouzané Cedex, France aut ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 443-447 1054-3139 53:2<443 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0062 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0062 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Marchal Emile ORSTOM, Institut Océanographique 195 rue Saint Jacques, F75005 Paris, France aut NATIONALLICENCE 700 1- Lebourges Anne Centre ORSTOM de Brest BP 70, F29280 Plouzané Cedex, France aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 443-447 1054-3139 53:2<443 1996 53 icesjms Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford