Infection of wild fishes by the parasitic copepod Caligus elongatus on the south east coast of Norway

Heuch, Peter Andreas; Øines, Øivind; Knutsen, Jan Atle; Schram, Thomas A.

doi:10.3354/dao01833

Cited by 32 publications

(28 citation statements)

References 24 publications

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“…infestations cause reductions in condition in cod and saithe, although heavy infestation of Clavella adunca can produce a moderate reduction in cod condition [20]. However, mobile sea-lice infestations of gadoids were generally close to the range of those typically recorded in Norwegian fjord and coastal waters (1 to 2 C. elongatus gadoid −1 ; [26]). L. branchialis is considered the most serious metazoan parasite of wild cod [18], [20] and can cause mortality, loss of condition and affect reproductive output.…”

Section: Discussionmentioning

confidence: 76%

Proxy Measures of Fitness Suggest Coastal Fish Farms Can Act as Population Sources and Not Ecological Traps for Wild Gadoid Fish

et al. 2011

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BackgroundEcological traps form when artificial structures are added to natural habitats and induce mismatches between habitat preferences and fitness consequences. Their existence in terrestrial systems has been documented, yet little evidence suggests they occur in marine environments. Coastal fish farms are widespread artificial structures in coastal ecosystems and are highly attractive to wild fish.Methodology/Principal FindingsTo investigate if coastal salmon farms act as ecological traps for wild Atlantic cod (Gadus morhua) and saithe (Pollachius virens), we compared proxy measures of fitness between farm-associated fish and control fish caught distant from farms in nine locations throughout coastal Norway, the largest coastal fish farming industry in the world. Farms modified wild fish diets in both quality and quantity, thereby providing farm-associated wild fish with a strong trophic subsidy. This translated to greater somatic (saithe: 1.06–1.12 times; cod: 1.06–1.11 times) and liver condition indices (saithe: 1.4–1.8 times; cod: 2.0–2.8 times) than control fish caught distant from farms. Parasite loads of farm-associated wild fish were modified from control fish, with increased external and decreased internal parasites, however the strong effect of the trophic subsidy overrode any effects of altered loads upon condition.Conclusions and SignificanceProxy measures of fitness provided no evidence that salmon farms function as ecological traps for wild fish. We suggest fish farms may act as population sources for wild fish, provided they are protected from fishing while resident at farms to allow their increased condition to manifest as greater reproductive output.

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Section: Discussionmentioning

confidence: 76%

Proxy Measures of Fitness Suggest Coastal Fish Farms Can Act as Population Sources and Not Ecological Traps for Wild Gadoid Fish

et al. 2011

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“…Salmon aquaculture may affect the organisms living around the farms, for example by increasing the risk of parasite and disease transfer between cultured organisms and the wild fauna. An ectoparasitic copepod, the sea louse Caligus elongatus, is found on more than 80 different fish species (Kabata 1979), and lumpsuckers are among the preferred hosts of C. elongatus (Øines et al 2006;Heuch et al 2007;Øines and Heuch 2007). C. elongatus is recognized as a problem for the Atlantic salmon Salmo salar farming industry (Pike and Wadsworth 1999;McKenzie et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Movements of lumpsucker females in a northern Norwegian fjord during the spawning season

et al. 2011

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The lumpsucker Cyclopterus lumpus is distributed throughout the North Atlantic Ocean and migrates considerable distances between offshore feeding areas and shallow inshore spawning grounds. The number of the lumpsucker has declined since the mid 1980s, probably as a result of overexploitation. The lumpsucker is the preferred host of the sea louse Caligus elongates, which is a problem for marine aquaculture. However, little is known about the biology of the lumpsucker. The aims of the study were to 1) examine the movements of female lumpsucker during the spawning migration, and 2) assess the potential for lumpsucker to act as a vector for transmission of parasites and diseases between aquaculture farms and wild fish. Twenty female lumpsuckers tagged with acoustic transmitters were released during the spawning season in the inner part of Øksfjord, northern Norway and their distribution was recorded by 22 automatic acoustic receivers. The average time until departure from the fjord was 3 days, and within 1 week all fish had left the fjord. Timing of departure from the fjord was unrelated with either tidal current patterns or the time of the day. A high proportion of the fish (75%) were recorded within 200 m of fish farms, but they did not stay for extended periods at these farms. Our results suggest that mature female lumpsucker exhibit a movement pattern characterized by rapid fjord-scale migrations during the spawning season, and that they are not attracted to salmon farms in the same way as a range of other fish species.

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“…Lumpfish Cyclopterus lumpus is a major host for C. elongatus (Box -shall 1974, Heuch et al 2007. It is possible that the very low C. elongatus infection and absence of L. branchialis on farmed cod is at least partly due to the farm cages being remote from the lumpfish habitat.…”

Section: Noteworthy Absentees and Unfulfilled Predictionsmentioning

confidence: 99%

“…25% of the adults (Table 4). Both C. elongatus and C. curtus can use a range of wild fish species as hosts (Boxshall 1974, Heuch et al 2007) and should thus be able to seed the waters near the farms with infective stages. Some loss of adults of this species will occur during sampling, but that will be true for all fish groups.…”

Section: Noteworthy Absentees and Unfulfilled Predictionsmentioning

confidence: 99%

Parasite faunas of farmed cod and adjacent wild cod populations in Norway: a comparison

Heuch¹,

Jansen²,

Hansen³

et al. 2011

Aquacult. Environ. Interact.

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Atlantic cod Gadus morhua L. is host to more than 120 parasite species. Background abundance of these parasite species on adjacent wild hosts determines the infection pressure on cod farmed in open pens. In 2006In and 2008 cod were collected from 4 locations along the coast of Norway: Øks-fjord, Kvarøy, Brønnøysund and Ålesund. Freshly killed wild local cod, wild migratory cod, hatchery-reared farmed cod and wild-caught farmed cod were given a complete autopsy according to a standardized protocol. A total of 343 cod were examined, from which 48 parasite taxa, including 37 named species, were recorded. Wild local cod had the most diverse parasite fauna. Wild-caught farmed cod had a more diverse parasite fauna than the wild migratory cod, and the latter had 2 more parasite taxa than the hatchery-reared cod. The most common parasites in hatchery-reared cod were the digenean Cryptocotyle lingua, the monogenean Gyrodactylus marinus and the protozoans Spironucleus torosa and Trichodina spp. Other parasites occurring frequently in hatchery-reared cod were the parasitic copepod Cresseyus confusus, the myxosporean Zschokkella hildae and the nematode Hystero thy lacium aduncum. The nematode and digenean fauna of the hatchery-reared fish was sparse compared to wild cod and the wild-caught farmed cod. Caligid copepods were very rare on the hatchery-reared cod. These results support the hypothesis that food-borne parasites, such as nematodes and mature stages of digeneans, are most unlikely to become a health problem for farmed cod, and that parasites with simple life cycles and pelagic transmission stages, such as monogeneans and trichodinids, may dominate the parasite fauna of farmed cod in the future

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Infection of wild fishes by the parasitic copepod Caligus elongatus on the south east coast of Norway

Cited by 32 publications

References 24 publications

Proxy Measures of Fitness Suggest Coastal Fish Farms Can Act as Population Sources and Not Ecological Traps for Wild Gadoid Fish

Proxy Measures of Fitness Suggest Coastal Fish Farms Can Act as Population Sources and Not Ecological Traps for Wild Gadoid Fish

Movements of lumpsucker females in a northern Norwegian fjord during the spawning season

Parasite faunas of farmed cod and adjacent wild cod populations in Norway: a comparison

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