Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Size and visibility of Baltic cod eggs with reference to size‐selective and stage dependent predation mortality

Size and visibility of Baltic cod eggs with reference to size‐selective and stage dependent... Size of Baltic cod eggs from incubation experiments and from field samples was determined by microscopic analysis. Results from plankton samples were compared with corresponding size distributions of cod eggs found in herring stomachs. The influence of fixation on size of different developmental stages was studied. Live eggs from incubation experiments were also sized repeatedly throughout the developmental period with an optical plankton counter (OPC) based on light attenuance measurements as this was assumed to be more closely related to the visibility of the eggs for potential predators than egg diameter as obtained by microscopic analysis. Preservation in formaldehyde solution caused a small reduction in egg diameter (2.2%) whereby no differences between the developmental stages were detected. Egg size decreased slightly during incubation (6.9%) while the OPC measurements revealed a substantial increase in light attenuance during egg development (42.2%). In the field, a general decrease in egg size with increasing depth was observed while no change between the developmental stages was detectable. The mean size of eggs ingested by herring was slightly lower than in the water column which was most pronounced for the late stages containing a well‐developed embryo. The frequency of eggs in an advanced stage of development was considerably higher in the stomachs than in corresponding plankton samples. Therefore, it is suggested that the selection of further developed egg stages by predatory fish in the central Baltic Sea, i.e. herring and sprat, is due to an increase of visibility during egg development in relation to growth and pigmentation of the embryo. Thus it is likely that egg mortality due to predation is stage‐dependent rather than strictly size‐selective. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Applied Ichthyology Wiley

Size and visibility of Baltic cod eggs with reference to size‐selective and stage dependent predation mortality

Wieland, K.; Köster, F. W.
Journal of Applied Ichthyology , Volume 12 (2) – Jul 1, 1996
Download PDF
7 pages

Loading next page...
 
/lp/wiley/size-and-visibility-of-baltic-cod-eggs-with-reference-to-size-846ItyD0y4

References (29)

Publisher
Wiley
Copyright
Copyright © 1996 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0175-8659
eISSN
1439-0426
DOI
10.1111/j.1439-0426.1996.tb00067.x
Publisher site
See Article on Publisher Site

Abstract

Size of Baltic cod eggs from incubation experiments and from field samples was determined by microscopic analysis. Results from plankton samples were compared with corresponding size distributions of cod eggs found in herring stomachs. The influence of fixation on size of different developmental stages was studied. Live eggs from incubation experiments were also sized repeatedly throughout the developmental period with an optical plankton counter (OPC) based on light attenuance measurements as this was assumed to be more closely related to the visibility of the eggs for potential predators than egg diameter as obtained by microscopic analysis. Preservation in formaldehyde solution caused a small reduction in egg diameter (2.2%) whereby no differences between the developmental stages were detected. Egg size decreased slightly during incubation (6.9%) while the OPC measurements revealed a substantial increase in light attenuance during egg development (42.2%). In the field, a general decrease in egg size with increasing depth was observed while no change between the developmental stages was detectable. The mean size of eggs ingested by herring was slightly lower than in the water column which was most pronounced for the late stages containing a well‐developed embryo. The frequency of eggs in an advanced stage of development was considerably higher in the stomachs than in corresponding plankton samples. Therefore, it is suggested that the selection of further developed egg stages by predatory fish in the central Baltic Sea, i.e. herring and sprat, is due to an increase of visibility during egg development in relation to growth and pigmentation of the embryo. Thus it is likely that egg mortality due to predation is stage‐dependent rather than strictly size‐selective.

Journal

Journal of Applied Ichthyology – Wiley

Published: Jul 1, 1996

There are no references for this article.