EFSA’s scientific advice on aquatic species susceptible to specified diseases
The Animal Health and Welfare Panel (AHAW) of the European Food Safety Authority reviewed available scientific evidence for a number of fish and shellfish (molluscs and crustaceans) species in order to identify their potential susceptibility to certain diseases specified in the European Union list of susceptible species.
The result of this work can serve as a basis for the European Commission to update the list of susceptible species farmed in Europe and/or imported into Europe, and to help establish the most appropriate disease control measures.
The Panel investigated whether species indicated in the EU list should, in the light of the new scientific evidence, no longer be considered as susceptible, or if species other than those already listed could be considered as susceptible.
Scientists were able to single out various species whose susceptibility is supported by sound scientific evidence; including some which are not currently part of the list. The Panel recommends that these latter should be considered for possible inclusion in the list.
However, for a wide group of fish species, scientists were able to retrieve only partial evidence suggesting susceptibility of the species to specific pathogens or no evidence at all. In both cases, the Panel is recommending further studies to investigate their susceptibility.
The scientific opinion identified a wide range of species, representing many groups of aquatic animals, susceptible to the 14 diseases of fish, molluscs and crustaceans specified in the list.
Results of the scientific review also highlighted many species susceptible to a high number of diseases such as: Epizootic Ulcerative Syndrome, Viral Haemorrhagic Septicaemia, White Spot, and Yellow Head Disease. Scientists also indicated that some species are susceptible not only to one but to several disease agents. Scientists stressed that these species are likely to present a higher level of risk than the species which are susceptible only to one disease.
The work was carried out by scientists in the AHAW Panel who gathered and reviewed the most up-to-date, peer-reviewed, scientific literature in the field. Panel scientists, supported by external experts, developed a set of scientific criteria to objectively assess pathways for the infection and the response to such infections in the various species. These criteria were applied to assess the susceptibility of the species.
A scientific revision of the Directive lists of susceptible fish and shellfish species was deemed necessary by the European Commission in the light of significant development of the European and global aquaculture industry with new types of farming practices involving an increasing number of aquatic animal species.
 The diseases of aquatic animals are listed in Part II of Annex IV of EC Directive 2006/88. This directive on animal health requirements for aquaculture animals and products thereof, and on the prevention and control of certain diseases in aquatic animals, lists certain aquatic animal diseases and the fish species susceptible to those diseases and to act as a vector in the transmission of such diseases.
[Directive 2006/88/EC defines susceptible species as “any species in which infection by a disease agent has been demonstrated by natural cases or by experimental infection that mimics the natural pathways”. However, several problems with the applicability of the definition have been raised. These problems are linked to difficulties to scientifically demonstrate scientifically whether an experimental infection under certain conditions mimics the natural pathways or not, and to differentiate between infection by disease agents or contamination. These problems may hamper the listing of one species as susceptible. It was therefore necessary to define a set of scientific criteria for the assessment of host species susceptibility. The set of criteria were applied to the species listed in the European Union list of susceptible species and to other susceptible species in order to determine which species could be considered as susceptible to the listed diseases.]
 These species were classified in Group I and are listed in Table 4, pages 24-25 of the Scientific opinion.
 These species are listed in Table 6, pages 28-29 of the Scientific opinion.
 These species were classified in Group II and are listed in Tables 5 and 7, pages 25-28 and pages 29-30 of the Scientific opinion.
See the full opinion on Aquatic species susceptible to diseases: Opinion (PDF).