An evaluation of the effectiveness of oblique and step tows for collecting leptocephali

Paired tows oftne Isaacs Kidd Midwater Trawl (IKMT), namely oblique tow and step tow were used to determine which type of tow can be used to most efficiently sample assemblages of Leptocephali. Two tows in the Sulawesi Sea were made at the same approximate location on 3 October 2002. Both tows collected very similar assemblages of Leptocephali, despite minor differences in the length frequencies of some taxa. The assemblages collected by both tows were remarkably similar, suggesting that the amount of fishing effort of both types of tows was sufficient to adequately the sample abundant taxa of Ieptocephali. The collection of a few rare taxa such as Anguilla or Nettastomatidae in one or the other of the tows however, leaves the question of whether there are specific depth layers at which some taxa are more abundant, unanswered. But in general, the results of this experiment on towing styles shows that either type of towing technique may be sufficient to adequately sample the species assemblage of common species of Leptocephali in any particular area. Future research should use depth-specific sampling gear to determine if there are taxa specific depth layers in the Indonesian Seas and other areas.