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Title: The trophic ecology of the sandeel Ammodytes tobianus (L.) and other planktivorous fish species from Aberdeen bay
Author: Storey, G.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1993
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The fish population of Aberdeen bay was sampled monthly from 1989 to 1990, using a beach seine, with some additional samples being taken in 1991. The inshore sandeel Ammodytes tobianus was the most commonly caught fish species. Both herring (Clupea harengus) and sprat (Sprattus sprattus) were also caught in Aberdeen bay. While sandeels were caught throughout the year, herring and sprat were only present during the summer months. Zooplankton was sampled for each month in which the fish population was sampled. Density and composition of the zooplankton was shown to change dramatically throughout the year. The diet of sandeels, sprats and herring was examined for all months in which fishing was undertaken. The fish were divided into 10mm size classes. The percentage of stomachs containing food, stomach fullness and wet weight of stomach contents was recorded. No relationship between any of the above with season was noted. There was, however, a general trend for longer fish within a species, to have a greater wet weight of stomach contents. The diet of all three species of fish was dominated by calanoid copepods. Prey items that dominated the zooplankton numerically were often dominant in the diet of the fish. On several occasions dominant prey types were ignored, suggesting that all three species of fish can be both highly selective and opportunistic in their exploitation of the available zooplankton. Evidence of ontogenetic shifts in diet were apparent for sandeels, with larger fish consuming larger prey taxa, although this pattern was not consistent. As well as changes to larger prey taxa, changes were also observed to different prey taxa of a similar size. Shifts were apparent between sandeels differing in length by only 10mm. The lengths of the different prey taxa consumed by all three fish species were recorded. On the basis of size of prey taxon there was little evidence of resource partitioning between these fish species. There was, perhaps, more evidence of a division of resources by prey type.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available