Seasonal abundance and microhabitat use of bullhead Cottus gobio and accompanying fish species in the River Avon (Hampshire), and implications for conservation

Abstract

ABSTRACT1. Five side-channels and small tributaries of the River Avon (Hampshire, UK) were examined between spring 1999 and spring 2000 using point abundance sampling by electrofishing to determine the status of fish listed in Annex II of the EC Habitats Directive prior to habitat management works to enhance spring feeding habitat of wading birds.2. Seasonal patterns of abundance and microhabitat use of bullhead Cottus gobio and accompanying fish species were examined. Parr of Atlantic salmon Salmo salar were sufficiently abundant for microhabitat analysis at one site only. Only two specimens of brook lamprey Lampetra fluviatilis were observed, one at each of two sites. Bullhead was amongst the most abundant fish species at all five sites, 0+ bullhead predominating.3. Bullhead microhabitat preferences were generally similar at all five sites, but seasonal variations were observed, as was the case for the accompanying fish species, which included dace Leuciscus leuciscus, chub Leuciscus cephalus, stone loach Barbatula barbatula, roach Rutilus rutilus, and threespine stickleback Gasterosteus aculeatus.4. Bullhead conservation status is discussed, in particular the possible exemption of British bullhead populations, such as already granted for those of Finland, from Annex II of the Habitats Directive. # Crown

Assessment of the conservation status of endemic sculpinCottus haemusi(Cottidae) in the river Vit (Danube Tributary), northwest Bulgaria

“…The mean occurrence of the 0+ individuals was less than 5%. These results differed significantly from those reported for Cottus gobio in UK SAC rivers, where the one-summer-old individuals accounted for 95% of the population (Cowx and Harvey, 2003;Carter et al, 2004). It is considered that to achieve favourable conservation status, more than 40% of the bullhead population in a discrete section of a river should be in the 0+ age class (Cowx and Harvey, 2003).…”

“…Appreciable differences in bullhead abundance from site to site were also found in the Garonne stream system (Legalle et al, 2005). In those parts of northern Europe in which bullhead populations are not threatened and the species is quite common or even abundant, abundances of less than 0.2 individuals·m -2 and 0.5 individuals·m -2 for upland rivers and lowland rivers respectively indicate sites with unfavourable conditions (Copp et al, 1994;Carter et al, 2004;Cowx and Harvey, 2003;Cowx et al, 2009). There are several possible reasons for the relatively low abundance of C. haemusi in the river Vit tributaries.…”

“…The data from the length frequency analysis suggested that the investigated Vit sculpin populations contained more than three age classes. According to bibliographic sources, the 40 to 45 mm size group was defined as one summer old (0+) (Cowx and Harvey, 2003;Carter et al, 2004;Abdoli et al, 2007). We assumed that the next size group -fish of 50 to 90 mm in length -corresponds to the 1+ age group.…”

“…The habitat preferences of Cottus species have been described in several studies (e.g. Tomlinson and Perrow, 2003;Carter et al, 2004;Kotusz et al, 2004;Legalle et al, 2005;Legalle, 2008;Gosselin et al, 2010). Investigation of the abundance, age and growth rate of sculpins revealed variation not only between species, but also between populations from different locations (e.g.…”

“…Investigation of the abundance, age and growth rate of sculpins revealed variation not only between species, but also between populations from different locations (e.g. Mann, 1971;Crisp et al, 1974;Welton et al, 1983;Waterstraat, 1992;Perrow et al, 1997;Fischer and Kummer, 2000;Jansen et al, 2000;Cowx and Harvey, 2003;Carter et al, 2004;Kotusz et al, 2004;Legalle et al, 2005;Van Liefferinge et al, 2005;Abdoli et al, 2007). The spread of local populations of bullhead has been hampered by the low migratory ability of the species, its specific ecological requirements and river fragmentation (natural and man-made), which have prevented significant dispersal (Utzinger et al, 1998;Fischer and Kummer, 2000;Knaepkens et al, 2005).…”