SPATIAL ANALYSIS AND DISTRIBUTION OF PISCIRICKETTSIA SALMONIS ON WILD AND FERAL FISH POPULATIONS IN SOUTHERN CHILE
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1
Instituto de Fomento Pesquero, Chile
The geographical distribution of fish pathogenic bacterium P. salmonis in wild and feral fish populations is unknown, including its transmission dynamic. The use of spatial epidemiology techniques contribute to detection of new congregations or prevalent areas of infection, thus generating the establishment of risk zones for wild and eventually, farmed fish populations. The aim of this study was to describe the P. salmonis spatial distribution on wild and feral fish populations in the geographical regions of Chile with important aquaculture activity. Wild and feral fish populations were caught in Los Lagos and Aysén regions in southern Chile, area where it has been established the administrative system of Salmonids Concessions Group (SCG), which include different sea farms in the Chilean salmon industry. The data from the surveillance program, executed by Instituto de Fomento Pesquero (IFOP), was analyzed from 2014 to 2016. The whole information was analyzed with ArcGIS® v10.4 for the identification of spatial patterns of positives samples by Moran´s I spatial autocorrelations for each SCG. From P. salmonis positive PCR results, the proportions of positive samples over the total captures for each SCG were estimated. The results showed that from the 3113 fish caught, 240 samples were positive to P. salmonis (8% of the total). From these positives fish, 63% corresponded to Eleginops maclovinus, 28% to Odontesthes regia, 4% to Salmo salar, 2% for both Oncorhynchus kisutch and Oncorhynchus mykiss, and 1% to Salmo trutta fario. In the 2016, the zones with highest occurrence were SCG-17b (31%), SGC-10a (22.4%) and SCG-6 (11.3%) all located in the Los Lagos region. The spatial correlations (Moran´s I) of the positives samples showed randomized patterns for 2014-2015 period (z-score= 0.68; p= 0.45), and for 2015-2016 period (z-score= -0.57; p=0.56). The results suggest a random pattern of P. salmonis prevalence in wild and feral fish, situation according with the distribution of the occurrence of P. salmonis outbreaks in the salmon farms in southern Chile. Therefore, the number of zones included in the surveillance program should be increase and supported by the phylogenetic analysis P. salmonis positives samples from wild and feral populations. Furthermore, it is necessary to investigate the epidemiological role in the P. salmonis transmission of the wild fish species Eleginops maclovinus.
Acknowledgements
This work was funded in large part, by the Undersecretariat of Fisheries and Aquaculture. Chilean Government.
Keywords:
Piscirickettsiosis,
Wild fish,
Chile,
Eleginops maclovinus,
Aquaculture
Conference:
AquaEpi I - 2016, Oslo, Norway, 20 Sep - 22 Sep, 2016.
Presentation Type:
Poster
Topic:
Aquatic Animal Epidemiology
Citation:
García
J,
Contreras-Lynch
S and
Espinoza
C
(2016). SPATIAL ANALYSIS AND DISTRIBUTION OF PISCIRICKETTSIA SALMONIS ON WILD AND FERAL FISH POPULATIONS IN SOUTHERN CHILE.
Front. Vet. Sci.
Conference Abstract:
AquaEpi I - 2016.
doi: 10.3389/conf.FVETS.2016.02.00064
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Received:
14 Sep 2016;
Published Online:
15 Sep 2016.
*
Correspondence:
DVM. Juan Pablo García, Instituto de Fomento Pesquero, Puerto Montt, Chile, juanpablo.garcia@ifop.cl