Health status of rudd (Scardinius erythrophthalmus hesperidicus H.) in Lake Vrana on the Island of Cres, Croatia

Abstract

The health status of rudd (Scardinius erythrophthalmus hesperidicus H.) in Lake Vrana, the largest Croatian karstic lake, was evaluated. Studies comprising parasitological, haematological and bacteriological surveys were conducted over a 2‐year period. Parasitological examination revealed a light infestation of 27% of the examined fish, mostly Dactylogyrus and Ichthyophthirius species. Haematological studies showed that haematocrit values were lower than the physiological limit. A haematocrit coefficient of correlation in all research periods was higher than 15%, indicating that the majority of fish in the study were susceptible to the development of bacterial and other diseases. Indeed, a diverse array of bacteria were isolated from rudd, mainly Flavobacterium spp. and Aeromonas spp., but also some specific fish pathogens, notably Pasteurella piscicida, Yersinia ruckeri, and Edwardsiella ictaluri, were identified. Under stress conditions, detected bacterial species can give rise to disease outbreaks.

Comparative blood biochemistry of Amur sturgeon, Acipenser schrenckii, and Chinese surgeon, Acipenser sinensis

“…The ranges of serum chemistry variables of fish can be influenced by many biotic and abiotic factors such as age, sex of fish, water temperature, seasonal pattern, and feeding status (Burtis and Ashwood 1996;Topic´Popovic´et al 2001;Al-Salahy 2002;Sala-Rabanal et al 2003;Ř ehulka et al 2004). Fish tended to have much larger Note: The significance level was set at P<0.05; the highly significance level was set at P<0.01.…”

Simple and rapid detection of Photobacterium damselae ssp. piscicida by a PCR technique and plating method

“…1996; Candan et al. 1996; Topic Popovic et al. 2001) have encountered similar high mortalities in cultured sea bass ( Dicentrarchus labrax ) and sea bream ( Sparus aurata ).…”

A new maximum length and weight for Scardinius erythrophthalmus

“…The captured rudd was a female of 617 mm TL, 541 mm SL and weighed 3.623 g. According to Topić‐Popović et al. (2001), in Vrana Lake the maximum SL is 325 mm for males and 296 mm for females, and maximum weight 736.5 g; however, our specimen proves that this species can grow above the previous maximum data found.…”

“…With a surface area of 5.7 km 2 and maximum depth of 78 m Vrana Lake represents one of the largest freshwater lakes on the relatively small and entirely karstified Island of Cres in the Adriatic Sea (N44°52′18′; E14°22′38′). Besides rudd only three other fish species inhabit the lake: tench ( Tinca tinca ), chub ( Leuciscus cephalus ) and pike ( Esox lucius ) (Topić‐Popović et al., 2001). The Vrana Lake rudd has been studied extensively, with no registered hybrids (Tomec et al., 2003).…”