Parasites, diseases and disorders

Abstract

It is apparent from the fossil records in Europe (Berg, 1936) and North America (Wilson and Williams, 1992) that the family Esocidae is ancient. Their major feeding innovation of depressible teeth, dorsoventrally flattened mouth, and vomerine dentition is also ancient (Wilson and Williams, 1992) and indicates that predatory feeding is very old in this family. Consequently it is likely that some of their parasites and pathogens are ancient as well and may be related to the history of predatory feeding. However, it is unlikely that predator—prey interactions have remained unchanged over time; consequently their present parasite communities may reflect a more recent pattern of feeding and may not contain many co-evolved species. A comparison of esocid parasites between continents may indicate historical predator—prey interactions and a review of their current parasitofauna may give insight into their feeding patterns. This is especially true for those endohelminths specific to the esocids, and possibly of ancient origin, as well as for the less host-specific groups. At present the family Esocidae is represented by five species (Chapter 1); the pike, Esox lucius, is mainly Holarctic/circumboreal in distribution but covers a broad latitudinal range, occurring as far south as the Caspian Sea drainages. The only other species of Esox in Eurasia, the Amur pike, E. reicherti, is endemic to the Amur River basin. In contrast, there seems to have been considerable speciation in North America, i.e. muskellunge, E. masquinongy, chain pickerel, E. niger, and redfin and grass pickerels, E. americanus, despite some historical controversy regarding their taxonomy (Lee et al., 1980).