Foraging behavior in early Atlantic cod larvae (Gadus morhua) feeding on a protozoan (Balanionsp.) and a copepod nauplius (Pseudodiaptomussp.) |
| |
Authors: | I Hunt von Herbing S M Gallager |
| |
Affiliation: | (1) School of Marine Sciences, University of Maine, Orono, Maine 04469, USA e-mail: ivonherb@umenfa.maine.edu; Fax: +1-207-5814388, US;(2) Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA, US |
| |
Abstract: | Food limitation is likely to be a source of mortality for fish larvae in the first few weeks after hatching. In the laboratory,
we analyzed all aspects of foraging in cod larvae (Gadus morhua Linnaeus) from 5 to 20 d post-hatching using protozoa (Balanion sp.) and copepod nauplii (Pseudodiaptomus sp.) as prey. A camera acquisition system with two orthogonal cameras and a digital image analysis program was used to observe
patterns of foraging. Digitization provided three-dimensional speeds, distances, and angles for each foraging event, and determined
prey and fish larval head and tail positions. Larval cod swimming speeds, perception distances, angles, and volumes increased
with larval fish size. Larval cod swam in a series of short intense bursts interspersed with slower gliding sequences. In
94% of all foraging events prey items were perceived during glides. Larval cod foraging has three possible outcomes: unsuccessful
attacks, aborted attacks, and successful attacks. The percentage of successful attacks increased with fish size. In all larval
fish size classes, successful attacks had smaller attack distances and faster attack speeds than unsuccessful attacks. Among
prey items slowly swimming protozoans were the preferred food of first-feeding cod larvae; larger larvae had higher swimming
speeds and captured larger, faster copepod nauplii. Protozoans may be an important prey item for first-feeding larvae providing
essential resources for growth to a size at which copepod nauplii are captured.
Received: 20 April 1999 / Accepted: 12 January 2000 |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|