Title: Spring Carp Mortality Syndrome (SCMS) Transmission Study
Author: J. Armitage
Author: K. Denham
Author: N. Hewlett
Author: J. Snow
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_1227, Representation ID: 397, Object ID: 2441
Abstract:
The carp, Cyprinus carpio, is the most popular sporting fish in England and Wales. During the late 1980s and 1990s concern grew over widespread and large-scale carp mortalities in fisheries throughout England and Wales. In some cases over 90% of the carp population died, however there was no obvious cause of mortality. The mortalities occurred during spring or early summer and did not appear to be related to fish size, age or sex. Mortalities of this nature have been termed Spring Carp Mortality Syndrome (SCMS). Five large carp were sampled from a suspected SCMS mortality at Riverside Lake, Doncaster in May 2003. The carp were transported to the Cefas Laboratory, Weymouth. Samples of naïve carp (<1yr, 4-6cm) were sourced from two suppliers. Mirror carp and ghost carp were obtained from Bow Lake, Hampshire Carp Hatcheries and mirror carp from Priory Fisheries. An additional sample of larger carp(12-16cm) was obtained from Fishers Pond, Hampshire. This study has provided some evidence for the presence of an infectious agent in fish from Riverside Lake. Virological investigation recorded a slow growing agent causing a CPE on KF cells from a Riverside carp. Further investigation showed that the CPE could be passaged onto EPC cells to produce a productive infection. Investigation by electron microscopy also shows evidence of the presence of herpes-like virus particles. However, this CPE was not consistent with KHV, as KHV produces a transient CPE in EPC cells with no productive infection. KHV DNA was however detected in another Riverside carp, though this was a low-level positive result. During summer and autumn 2003, the Environment Agency and Cefas investigated several other carp mortality events. A small number of these sites tested positive for KHV DNA by single-round or nested PCR. At one of these sites, KHV was isolated from gill tissue on KF cells. The source of these outbreaks remains unknown, however they could have occurred through linked stockings of fish from an infected site. Ornamental carp species were also present at some of the sites, providing a potential route of infection. Clinical signs of KHV occur between 17 and 27 degrees C (experimentally between 15 and 28C). It is possible that water temperatures at Riverside Lake could have been as high as 17C during May and therefore conducive to KHV, however evidence from virological examination indicates that despite KHV being present in the sample, another pathogen was present that could have been implicated in the mortality. Evidence suggests that the presence of an infectious agent within the Riverside carp is the likely cause of the mortalities in the naïve carp. Though KHV was detected in one Riverside carp, it seems unlikely that this was the primary cause of the mortality. In the absence of additional investigations, there is also little evidence to suggest the presence of bacterial toxins within the sample. Following this experiment, the causative agent of SCMS remains undetermined. Collaborative work between the Environment Agency, Cefas and the English Carp Heritage Organisation (ECHO) will continue to further the understanding of SCMS and identify the causative agent.
Publisher: Environment Agency
Subject Keywords: Lakes; Pathology; Coarse fishes; Fish diseases; Virology; Ponds; Virology
Taxonomic Keywords: Cyprinus carpio
Extent: 8
Permalink: http://www.environmentdata.org/archive/ealit:4661
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