Differential infectivity of Caligus flexispina (Copepoda, Caligidae) in three farmed salmonids in Chile (original) (raw)
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Aquaculture, 1998
A survey of parasitic copepods carried out in three introduced salmonid species in Southern Chile and 5 native fish species commonly found in the vicinity of the fish farm cages yielded 5 caligid species. Caligus flexispina, formerly found in the oceanic islands of the Pacific ocean, is currently the dominant species found in continental waters on native fish species (Eleginops maclovinus and Odonthestes regia) as well as on cultured trout Oncorhynchus mykiss from the south of Chile. Coho salmon O. kisutch and Atlantic salmon Salmo salar are more resistant to this parasite. Among the native fish species associated with netpen aquaculture, E. maclovinus harbours 4 caligid copepods, namely Lepeophtheirus mugiloidis, C. flexispina, C. teres and C. cheilodactylus (in the same order of ranked abundance). Odonthestes regia only harbours C. flexispina, whereas Paralichthys microps is a host of Lepeophtheirus edwardsi and C. flexispina. It is highly likely that the transfer of C. flexispina to salmonids is mediated by the presence of these native fish species.
Journal of the Marine Biological Association of the United Kingdom, 1989
Infestation of cage cultured Atlantic salmon by the external parasitic copepods Caligus elongatus (Nordmann) and Lepeophtheirus salmonis (Kröyer) is a serious cause of loss of production in the commercial sea water culture of this species. The copepods feed on the mucus, skin and blood of their hosts (Kabata, 1974; Brandal et al., 1976) causing irritation and lesions. Loss in production due to infestation by lice occurs directly by the mortality of fish from osmotic shock and indirectly from a probable reduction in growth, from secondary infections such as vibriosis (Wootten et al., 1982) or by increasing vulnerability to ultraviolet radiation damage (McArdle & Bullock, 1987).
Life cycle of Caligus rogercresseyi, (Copepoda: Caligidae) parasite of Chilean reared salmonids
Caligus rogercresseyi, [Contrib. Zool. 69 (2000) 137] is the only caligid known to affect the salmon industry in Southern Chile. Economic losses due to reduced fish quality, cost of chemical treatment and outbreaks of other diseases such as the Piscirickettsiosis occur. The life cycle of C. rogercresseyi is described in rainbow trout reared in seawater tanks from observations made under natural conditions of light and temperature between January 1997 and April 1998. Fish were infected with laboratory-cultured larvae obtained from ovigerous females. Rainbow trout were periodically slaughtered for parasite collection and identification. C. rogercresseyi life cycle includes the following stages: two nauplius, one copepodid, four chalimus and the adult. No preadult stage was observed. Timing of the different stages of development was directly dependent on water temperature. The maturation of the eggs or the time for a complete life cycle took place at 45 days in July at 10.3 jC, 31 – 32 days in April at 12.4 and 12.8 jC, respectively, and at 26 days in November at 15.2 jC. In January, at 16.7 jC, only the appearance of first eggs were observed at 18 days. A simple degree – day (dd) model is proposed for each developmental stage between 4 and 17 jC, where the development rate is a linear function of the average temperature of water. Using this degree – day model, the proportion of fourth stage chalimus was maximum at 172 dd of effective temperature, adult males at 193 degree – days, adult females at 208 dd. The minimum temperature threshold is at 4.2 jC where there is no development of the parasite. The appearance of first eggs occurred at 231 dd and the first pigmented eggs at 277 dd. The temperature-independent degree – days value allowed to predict the timing of C. rogercresseyi life cycle at any temperature within the evaluated range.
Invertebrate Reproduction & Development, 1992
The intensity and timing of infestation events of caligid copepods in wild or cultured fish populations may be predicted from previous local production of nauplius I of the parasite. However, this relationship is not well established, the spatial scales over which it operates are unclear, and the role of host reactions to the inv-ding copepodid is unknown. Rate of development (and population structure), generation time and rate and actual reproductive output are temperature-dependent. In Ireland between five and seven generations of Lepeophfheirus salmonis (Krqer) can develop annually and generation time varies from over 120 days in winter to 23 days in summer. Host reactions may affect the rate of development of the parasite but are less important than temperature. Host reactions may also cause parasite mortality, but this effect is specific for individual host parasite associations. The distribution of L. salmonis in cultured host populations is typically normal but is very over-dispersed in wild populations with heavy infestations. Parasiteinduced morphological damage to the host is correlated with physiological impacts. Physiological effects are present even when morphological damage is slight and so intermittent chemotherapeutic control of infestations cannot prevent some parasite impact from occurring. Lepeophtheirus salmonis Salmo salar X X Tully (1989); White (1940) Salmo truna X Tully et al. (1993a, 1993b) Oncorhynchus nerka X Johnson (personal comm.) Galigus elongatus Salmo salar X Tully (1989), author unpub. Melanogrammus X Neilson et al. (1987) aeglefinus X Gadus morhua Neilson et al. (1987) Sciaenops ocellatus X Landsberg et al. (199 1) Clupea harengus X MacKenzie and Morrisson (1989) Galigus epidemicus Oreochromis X Lin and Ho (in press) mossambica Caligus curtus Salmo salar X Hogans and Trudeau (1989) Caligus minimus Dicentrarchus labrax X Paperna (1 980) Galigus spinosus Senola quinqueradiata X Izawa (1969) Galigus orientalis Oncorhynchus mykiss X Urawa and Kato (199 1)
Aquaculture Research, 2012
The reproductive success of Lepeophtheirus salmonis settled on host and non-host ¢sh has been compared. Triplicate single species tanks of Atlantic salmon, marine three-spined sticklebacks, saithe and Atlantic cod were exposed to 10 adult female L. salmonis per tank (n 5 30 lice per species). Adult female L. salmonis settlement and egg string production occurred only on salmon and cod, with no egg production occurring on saithe and three-spined sticklebacks. The number of eggs in egg strings, hatching success of eggs and the survival of all larval stages to the copepodid stage were severely a¡ected by the species of ¢sh on which female L. salmonis had settled. L. salmonis settled on cod produced signi¢cantly fewer eggs, lower hatching rates and lower survival rates of larvae than females on Atlantic salmon. The production of egg strings by L. salmonis females infecting cod, which successfully hatch and moult through to the infective copepodid stage, albeit in small numbers, is discussed in terms of the implications to aquaculture and salmon and cod farming scenarios.
Aquaculture Research, 1993
Abstract. Infestation parameters for the calígíd copepod Lepeophtheirus salmonis (Kroyer) infesting sea trout, Salmo trutta L., were established for a number of locations off the west coast of Ireland during 1990 and 1991. Based on these parameters sites were classified into two groups in 1990 and three in 1991. Median parasitic intensity in these groups was 11·6 and 77 in 1990 and 9·5, 29·5 and 55 in 1991. Fish were parasitized mainly by chalimus stages of the parasite which attached preferentially to the fins. Heaviest infestations were invariably due to chalimus stages and early pre-adult lice and there was a progressive decrease in the correlation between parasitic intensity and the number of each successive stage in the life cycle. This suggested either host or parasite mortality as the parasite matured. Large numbers of lice-infested fish returned prematurely from the sea to estuarine areas at a number of sites. Extensive morphological damage, especially to the fins, was apparent on a proportion of these fish as a result of the infestation. Mortality of heavily infested fish was directly observed.
Journal of Crustacean Biology, 2001
salmon, but farming of rainbow trout [Oncorhynchus mykiss (Walbaum, 1792) = Salmo gairdneri Richardson, 1836] has also been carried out on a much smaller scale, about The salmon louse Lepeophtheirus salmonis (Krøyer, 1838) is known to cause a serious problem in the farming of Atlantic salmon Salmo salar L., 1758, in northwest Europe and North America (Boxshall and Defaye, 1993; Pike and Wadsworth, 1999). So serious is the problem that an annual loss of 20% of the production was attributed to the infestations by this species of parasite (MacKinnon, 1997). Farming of coho salmon Oncorhynchus kisutch (Walbaum, 1792) in sea water has been in practice in Japan for more than two decades (Mahnken, 1991) and salmon louse has also been reported from both wild (Nagasawa, 1985; Nagasawa et al., 1987, 1994) and cultured salmonids (Nagasawa and Sakamoto, 1993; Urawa et al., 1998); yet, curiously, infestation by L. salmonis is not a serious problem in salmon farms in Japan. This paper reports the results of our study in an attempt to elucidate this distinct phenomenon. In Japan the culture of salmonids in sea water is largely operated along the Pacific coast of northern Honshu in Iwate and Miyagi Prefectures (Mahnken, 1991), with an annual production of over 20,000 metric tons in the early 1990s (Nagasawa and Sakamoto, 1993). The species being cultured are largely coho
ICES Journal of Marine Science, 1998
The occurrence of the parasitic copepod Lepeophtheirus salmonis Krøyer on sea trout Salmo trutta L. was studied in the Askerelva river and in the adjacent Oslo Fjord, southeastern Norway, where there are no salmon farms. Sampling was carried out in 1992 and 1993. Fishing was started in May, but no sea trout were caught in the river before August. Maximum prevalence (percent infested fish) in the monthly samples from the river was 50%, and the mean intensity (mean number of lice on the infested fish) in all river samples pooled was 19.9 parasites. Most were in the pre-adult or adult stage. The fish from the fjord were larger and had, in general, fewer lice than fish from the river (pooled mean intensity=7.6 lice), but the difference in mean intensity of infestation was not significantly different. There was no correlation between condition factor and the intensity of infestation on trout from the river nor from the fjord.