Lernaeocera branchialis: A Potential Pathogen to Cod Ranching

Abstract

A study was carried out to determine the effect of Lernaeocera branchialis on Atlantic cod infected in the laboratory and in the field and also to ascertain its effect on cod-ranching. Sixty-four percent (308) of 481 cod acquired infections in the laboratory and 33% (159) of the infected fish died over a 4-yr period. About 74% of the deaths occurred within 4 mo of the infection. Monthly samples of cod collected adjacent to a cod-ranching operation showed an initial prevalence of 30% that subsequently decreased in the following 2 mo to 15%. Prevalence of the infection also decreased among the initial field sample of cod that were kept alive, from 30 to 17% during the same 2-mo period and to 9% after 8 mo and was associated with death caused by the parasite. Cod examined at intervals after infection showed evidence of reduced weight gain, lower liver somatic index, liver lipid, and blood values than controls. A field sample taken from the same area during the summer of the following year indicated a prevalence of 12%. This higher than usual prevalence (4-6%) was associated with retention of the intermediate host, Cyclopterus lumpus, that provided an additional source of infective stages. It is likely that increased parasitism could affect the success of the cod-ranching operation in view of the parasite's devastating effects on its hosts.

The effects of the ectoparasite Tracheliastes polycolpus (Copepoda: Lernaeopodidae) on the fins of rostrum dace (Leuciscus leuciscus burdigalensis)

“…For instance, the copepod Salmincola decreases the resistance of its host to environmental stress (Vaughan and Coble 1975;Sutherland and Wittrock 1985) and may decrease the fecundity of female trout (Gall et al 1972). Lernaeocera branchialis, which parasitizes Gadidae living in the Arctoboreal region, has often been associated with host growth reduction (Khan et al 1993) and mortality (Khan and Lacey 1986;Khan et al 1990). Heavy T. polycolpus infestations may have been an additional stress factor contributing to rostrum dace mortality.…”

Description of the free-swimming juvenile stages of Lernaeocera branchialis (Pennellidae), using traditional light and confocal microscopy methods

“…Lernaeocera branchialis is recognised as a pathogen that could have major effects on the aquaculture industry (Khan et al 1990, Bricknell et al 2006. With renewed interest in L. branchialis as a result of the expansion of gadoid aquaculture in several North Atlantic countries, this re-description provides important information on its life history, which may form the basis of further research into this potentially devastating pathogen.…”

Pathology caused by adult Pseudochondracanthus diceraus (Copepoda:Chondracanthidae), a parasite of bullseye puffer fish Sphoeroides annulatus

“…In contrast, Bennett & Bennett (2001) found that fish had severe focal haemorrhage due to the penetration of the maxillipeds of the parasite copepod Dissonus manteri into the primary lamella of the leopard coral grouper Plectropomus leopardus, and anaemia was shown to be caused by Lernaeocera branchialis in haddock Melanogrammus aeglefinus (Lester & Roubal 1995), cod Gadus morhua (Khan et al 1990) and hake Merluccius merluccius (Guillaume et al 1985).…”