Trophic ecology of the Lanternfish Lampanyctus crocodilus in NW Mediterranean in relation to reproductive cycle and environmental variables

2013 Annual Symposium of the Fisheries Society of the British Isles (FSBI Symposium 2013) Deep Sea Fish Biology, 8-11 July 2013, Glasgow

The trophic ecology and distribution of the lanternfish Lampanyctus crocodilus was investigated over a wide bathymetric range (450-2200 m) and at a seasonal scale in the NW Mediterranean. The reproductive cycle and environmental variables were also analysed in order to identify drivers of the observed trends. Juveniles of the species (<9 cm TL) were more abundant on the upper (ca. 500-600 m of depth) and lower slope (ca. 1500 m), according to the distribution of deep zooplankton. Adults mostly inhabited on the middle slope (ca. 800-1000 m), while the greater number of mature females were found at 1000-1200 m. Reproduction took place in February (as measured by the GSI index) and it is driven by temperature and food availability as deduced by Generalized Linear Models. Consistently, the feeding ecology varied both seasonally and over the depth range explored. On the upper slope L. crocodilus mainly fed on euphausiids and mysids during all seasons, while below 1000 m euphausiids were also important prey together with gelatinous plankton in spring and mesopelagic fish in summer. In autumn L.crocodilus fed on a wider array of prey (suprabenthic gammariids, cumaceans, decapods).. Conversely, on the upper slope trophic diversity was greater in summer. Surface primary production recorded 2 months before sampling was responsible of fullness patterns, consistent with the expected delay between vertical food inputs and the response of benthopelagic species over the slope

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