Publication Abstract

Growth and life history traits of introduced pumpkinseed (Lepomis gibbosus) in Europe, and the relevance to invasiveness potential

Title: Growth and life history traits of introduced pumpkinseed (Lepomis gibbosus) in Europe, and the relevance to invasiveness potential

Gordon H. Copp and Michael G. Fox

The North American centrarchid, pumpkinseed Lepomis gibbosus (Linnaeus 1758), is a good example of how the life-history traits and biogeographical patterns of growth can vary in populations of introduced species, facilitating the establishment of new populations in novel environments. Introduced to Europe from North America in the late 19th century, the pumpkinseed is now established in at least 28 countries of Europe and Asia Minor. Scientific interest in the species in Europe began early, but studies of the species only really began in the mid 20^th century. Scientific output rose to about one publication per year in the 1970s, and then rose sharply during the 1990s and 2000s, with approximately half of the 12 papers on growth and life history of European pumpkinseed appearing in the last five years. Virtually all of the studies on pumpkinseed growth and life history included some form of limited comparison with populations from the species’ native and/or introduced ranges, and a common finding in most studies was the absence of sexual dimorphism in growth. In the late 1990s, the first comparative study of biological traits of native and introduced pumpkinseed populations was undertaken within the context of ecological theory: whether ectotherms living in warm thermal environments should mature early because of fast juvenile growth. This led to a critical review of the available data on the biological traits of European pumpkinseed compared to the only studied population from northern Europe (in England). This suggested that the later maturation and slower growth of a pumpkinseed population in southern England resulted from the combined effects of thermal regime, limited food resources and relatively high juvenile survivorship. Subsequent studies of other English pumpkinseed populations revealed the initial data point for northern Europe to be representative of the upper extent of the range of observable values for age and length at maturity as well as age-specific growth. From the information currently available, the degree of invasiveness of pumpkinseed in Europe appears to be a function of three factors: 1) life-history traits, with particular reference to age at maturity and juvenile growth rate of which both depend to a degree on temperature; 2) characteristics of the drainage basin/landscape into which the species was first introduced, with dispersal facilitated by watercourse and water body connectivity; and 3) human-assisted dispersal such as unauthorized fish movements and releases for angling amenity or religious reasons. To verify the importance of these factors, and provide advice on the management needs as regards non-native fish species, further study is needed of pumpkinseed populations in northern Europe as well as a detailed comparison between native and introduced populations of this species.

Reference

Copp, G.H. & Fox, M.G. 2007. Growth and life history traits of introduced pumpkinseed (Lepomis gibbosus) in Europe, and the relevance to invasiveness potential. pp. 289–306 In: Freshwater Bioinvaders: Profiles, Distribution, and Threats. (F. Gherardi ed.) Springer, Berlin.

G.H. Copp* and M.G. Fox

pp. 289-306 In: Freshwater bioinvaders: profiles, distribution and threats, Edited by F. Gherardi