GYRODACTYLUS SALARISand Atlantic Salmon

By

Jonathan Sheppard

Gyrodactylus Salaris Identification (Morphology, Life Cycle, Discovery and Origination)

Spread Pathways (Anthropogenic, Migration)

Impacts (Ecologically, Economically)

Management Methods (Prevention, Eradication)

Main Points

- Monogean skin/salmon fluke

- First discovered in 1957 in Sweden

- The host is the atlantic salmon parr

- “Salmon Killer”

Gyrodactylus Salaris

- Simplest life cycle

- Hyper-vivaparous and external (outside the host) reproductive strategy

- Progenesis

- “Russian Doll Effect”

Gyrodactylus Salaris

- Attaches to host with its posterior opisthaptor with 16!!! Sharp hooks

- Feeding occurs in the anterior end sucking up skin tissue and mucous

Gyrodactylus Salaris Morphology

Spreading in G. SalarisPathways of

• Originates from 3 native regions; Russia, and Baltic regions of Finland and Sweden

• In these regions the salmon have little to intermediate infection responses to G. Salaris

G. Salaris Spread

• G. Salaris now reaches the atlantic salmon population in Norway, Denmark and the west coast of Sweden

• Norway has recorded over 41 of their river systems being infected

G. Salaris Spread

• Anthropogenic movement of infected fish between hatcheries and fish farms in rivers

• Migration of infected fish in rivers and in brackish water through fiords

• Through the host transfer of other species of freshwater fish that does not support the parasite

Spread Pathways

Impacts of G. SalarisEcological and Economical

Infection from G. Salaris results in GYRODACTYLOSIS, early stages are:

Irritation; fish will undergo behaviours of rubbing and flashing

Later stages: Lethargic and isolating behaviours

G. Salaris and secondary infections ultimately lead to mortality

Ecological Impact

Signs of the disease are Ulcers on the skin Peeling of the skin Fish appearing pale Excess mucus on the skin

Ecological Impact

<100 in abundance sites are located on dorsal fin, pectoral and anal fin

>100 site specificity moves to the caudal fin

>1000 the body was infected

Ecological Impact - Specificity

The density of salmon parr in 14 of norways rivers have been reduced by 86%!!!

Since G. salaris’ discovery in norway 25 years ago it has cost >500 million euros

Without any measures, the G. salaris may have reduced the Norwegian salmon fishery by 15 %

Economic Impact

Management StrategiesPrevention, Eradication and Education

o Management strategies differs between countries

o Norway and Sweden’s strategy is eradication

o Denmark and Scotland are taking prevention and education strategies

Management Strategies

o Strict regulations are enforced on importing live

o Norway has produced posters to spread along rivers and methods to educate fishermen and others

o Some use of migration obstructions

Prevention and Education

Rotenone is used as a widespread chemical in the river systems

Has proven to be effective in smaller rivers

Laboratory experiments have shown effectiveness with acid aluminum

Eradication

Subdivisions of Gyrodactylus genus

Patterns of host specificity and host preference and evolutionary mechanisms of host switching

Further Research about G. Salaris

References

Johnsen B.O. (2006): NOBANIS – Invasive Alien Species Fact Sheet – Gyrodactylus salaris. – From: Online Database of the North European and Baltic Network on Invasive Alien Species – NOBANIS www.nobanis.org, Date of access x/x/200x.

Johnson, E. Skin Flukes (Gyrodactylus) Frank Prince-Iles ©2009 All Rights Reserved http://www.fishdoc.co.uk/disease/flukes.htm

Manual of Diagnostic Tests for Aquatic Animals 2009. www.oie.int/fileadmin/Home/eng/Health_standards/aahm/2010/2.3.03_Gyrodactylosis.pdf

Baake, T. et al. The Biology of Gyrodactylid Monogeneans: The ‘‘Russian-Doll Killers’’. ADVANCES IN PARASITOLOGY VOL 64

Baake, T. et al. DISEASES OF AQUATIC ORGANISMS. lished June 18 http://www.int-res.com/articles/dao/13/d013p063.pdf

Overview of the genus Gyrodactylu. Overview of the genus Gyrodactylusshttp://www.gyrodb.net/biology.php

Aquatic Animal Diseases Significant to Asia–Pacific Identification Field Guide. Parasitic diseases—Gyrodactylosis. http://library.enaca.org/Health/FieldGuide/html/fp001gyr.htm