Summary of Abstract Submission

Abstract Submission No. IO50-04-0040PresentationPoster

HORIZONTAL AND VERTICAL DISTRIBUTION PATTERNS OF MESOPELAGIC FISH LARVAE IN THE INDIAN OCEAN: INFLUENCE OF THE LEEUWIN AND AGULHAS CURRENTS.

M. Pilar Olivar*1, Lynnath Beckley2

1 CSIC, Spain
2 Murdoch University, Australia

ABSTRACT :

In this study we analyse the distribution of fish larvae in the Indian Ocean (off SE Africa and Western Australia in the Agulhas and Leeuwin Current systems), and relate it with the general hydrographic scenarios. Information on horizontal distributions in both regions was gathered from already published studies, and comparisons of the species occurrences and abundances were established. Notable similarities were observed in terms of species occurrences and abundances, e.g. larvae of the myctophids Scopelopsis multipunctatus, Hygophum hygomi and Diaphus spp. being dominant in both systems. Vertical distribution was analysed from stratified multi-net samples conducted in 2010 off Western Australia, covering both shelf and offshore zones, and both under the influence of the Leeuwin current and outside it. The majority of larvae belonged to Myctophiforms and Stomiiforms, although other groups such as Bregmacerotidae and eel leptocepali were also common. The most common and abundant were Scopelopsis multipunctatus, Lampanyctus alatus , Diaphus spp. and Vinciguerria nimbaria. More than 80% of fish larvae occurred in the upper 100 m of the water column and just 3% in the deepest layer (150-200 m) examined. Developmental stage was the most important factor differentiating the vertical position within species, although, in general, each species showed the same vertical pattern independently of the station¿s hydrography. Vertical patterns for the different genera and species in the Indian Ocean were compared to those of close relatives in other oceans, and a general similar pattern of vertical location within genera was observed.