A 25-year study of climatic and density-dependent population regulation of common shrimp Crangon crangon

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic; North Atlantic oscillation
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.496.7055; http://www.irchouse.demon.co.uk/pdf/crangonjmba2006.pdf

The results of a 25-year study of the population dynamics of the common shrimp, Crangon crangon, in the Bristol Channel are presented.The population size varied seasonally, with maximum abundance occurring in early autumn at the completion of annual recruitment.The number of recruits changed greatly between years, and was positively correlated with both average water temperature from January to August, and river £ow rate, and negatively correlated with theWinter North Atlantic Oscillation Index. A wide range of other physical and biotic variables was found to have no signi¢cant impact on C. crangon abundance. The positive relationship between temperature and C. crangon abundance observed for the Atlantic coast during this study is the opposite of that found for southern North Sea populations. Similar contradictory responses have been noted previously for £at¢sh such as sole, Solea solea. This suggests that global variables may act to produce di¡erent outcomes for Atlantic and North Sea populations of the same species. Over-winter mortality was found to vary with population size so that the adult C. crangon population in spring was found to be remarkably stable, and little in£uenced by temperature or other variables. The mortality rate increased with population size producing clear evidence of density-dependent control. It is suggested that this stability is linked to the constant limited availability of suitable habitat, with individuals unable to ¢nd shelter vulnerable to a range of predatory ¢sh. Given the pivotal role of C. crangon within the northern