Growth, morphology and life history traits of a cool-water European population of pumpkinseed Lepomis gibbosus

Abstract

We examined attributes of growth, reproduction, morphology and diet of a population of pumpkinseed Lepomis gibbosus introduced into a cool-water pond (Cot tesmore) in southern England, and compared them with available data on warm-water European populations. Morphologically, Cottesmore pumpkinseed appear to have a more streamlined body than the two southerly populations for which data are available, but this may be due to the small body size of the Cottesmore population. Ontogeneti cally, 11 morphological characters grew isometrically, 12 allometrically, and 3 split isometrically (i.e. a significant shift in proportional growth rate); however, the split 'break points' (between 49 and 60 mm SL) do not appear to correspond with any change in resource use or in biological process. Juvenile and age-specific growth were the lowest reported of any European population, and mean GSI was also low. Growth rate was highest in May and June, with condition highest in June, and with peak GSI in June and July. Mean age at maturity in the Cottesmore population was the highest re ported in Europe. Dietary overlap was high amongst most age classes, and there was evidence of cannibalism in the population. Late maturity of the Cottesmore population was probably the result of relatively low temperatures during the growing season, slow growth, poor condition at age 3 (due to limited food resources), and intensive egg predation by high numbers of juveniles, giving a fitness advantage to late-maturing fe males.

Life-history traits and potential invasiveness of introduced pumpkinseed Lepomis gibbosus populations in northwestern Europe

“…Also as predicted, pumpkinseed populations in northwestern Europe exhibited a trend of later age at maturity than populations at lower latitude (Table 3), and this relationship was significant when all available data for Europe were included. The latitudinal clines in juvenile growth and age at maturity proposed previously (Copp et al 2002;Villeneuve et al 2005) were only partially corroborated in the present study, as juvenile growth was not related to latitude when only the northwestern European populations were considered, nor to gonado-somatic index with either population database. This suggests that age at maturity is a more useful (and reliable) means of assessing, even in smaller data sets such as this (Table 2), the reproductive response of pumpkinseed to environmental variability than other reproductive indices, Fig.…”

“…Batts Bridge Stream (EBS) is a small tributary of the River Ouse (Sussex); it flows southward through a number of on-line ponds (Klaar et al 2004;Villeneuve et al 2005). Cottesmore School Pond (ECS) is a small man-made pond of Table 1) Life-history traits and invasiveness of northwestern European pumpkinseed 2173 about 0.7 ha area and constitutes the upper-most water body of a small stream system (Copp et al 2002). Airport Pond (EAP) is a small pond of about 0.72 ha area with a mean depth of 1.5 m located in the Isle of Wight (English Channel).…”

“…The slope parameter 'b' from the regression equation (log 10 W = b (log 10 TL) ± a) was used as an estimator of 'generalised' condition (sensu Pitcher and Hart 1982). Relationships between latitude and life-history traits (i.e., juvenile growth, adult growth, age at maturity, reproductive investment; proposed by Copp et al 2002) and between age at maturity and juvenile growth were examined using linear regression, initially on the northwestern European data set and subsequently on the entire dataset available for Europe (as compiled by Copp and Fox 2007). The relationship between age at maturity and juvenile growth is used as a means of assessing the potential invasiveness of pumpkinseed populations in Europe, whereby the transition phase between non-invasive and potentially invasive pumpkinseed populations is defined at its lower extent by the minimum age at maturity (age 1) and at its upper extent by the end of juvenile growth (which for many pumpkinseed populations is age 2, Fox 1994; Fox and Crivelli 2001;Copp et al 2004).…”

“…Introduced to European inland waters during the late nineteenth century, the pumpkinseed is now established in at least 28 countries of Europe and western Asia Minor . Apart from recent studies of pumpkinseed populations in England (Copp et al 2002;Villeneuve et al 2005), all previous studies of pumpkinseed growth and lifehistory under natural thermal conditions have been undertaken in southern and central Europe Fox et al 2007). However, the increased attention to northwestern populations has revealed pumpkinseed to be more widely distributed within countries of northwestern Europe than was previously believed (e.g.…”

Growth and morphology of an endangered native freshwater fish, crucian carp Carassius carassius, in an English ornamental pond

“…However, age-at-maturity is known to be variable in crucian carp (Scha¨perclaus, 1953), similar to other freshwater fish (e.g. Copp et al, 2002), as a result of variations in environmental conditions (e.g. Astanin and Podgorny, 1968) and without the slow-growing populations being classed as stunted.…”