Clinical inspection and sampling on the marine fish and molluscan farms and shipping of samples to the diagnostic laboratories Snježana Zrnčić, PhD, DVM TCDC/TCCT Consultant No 2 – Diagnostics

MOLLUSCAN FARMS

Collectors for mussels and oysters Cultivation in basket Cemented oysters

Cultivation of mussels on rafts Harvesting of natural, „wild”population of molluscs from molluscs production area (oysters, pectinids etc.)

General principles of molluscs sampling Cultivation of molluscs is semi-intensive or extensive Different cultivation gears like rafts, ropes, tables, trays, baskets etc. Some life stages are very mobile (spat) while adults are sessile Spat is very often collected from environment Wild, natural populations are very important for country or production area health status Abnormal mortalities (mortalities exceeded normal Mt in two weeks) „Clinical outbreak” – 10 moribund + 10 „healthy animals Health status – it depends on the programme (30 or 150 animals)

Sampling should include animals from inner and central part of the production area, close to surface, middle and close to bottom points of the water body They should reach laboratory alive Mussels should be packed tightly in the net to prevent opening while oysters should be packed in the layers with concave shell on the bottom of the package, covered with wet paper and then another layer They should be packed in cooling box with sufficient freezing blocks (not ice cubes) to prevent temperature exceed 10 o C Temp. under 10 o C will enable molluscs to stay alive for several days All data about sea temp., any other observation, sampling points should be recorded and packed into plastic back to prevent wetting and in lab, personnel will be able to read data

Water proof pencil is not the best way of marking the sample

It is obvious that the principle of random sampling was not obeyed

CLINICAL INSPECTION AND SAMPLING ON THE MARINE FISH FARM Marine cages are rectangular or round shaped but always vet should walk around the cage to observe behaviour of fish

Special attention should be payed to fish swimming close to bottom, exposing abnormal swimming behaviour, swimming close to the net...

Dark pigmented specimen, refusing feed etc.

Normal appearance of the shoal Specimen swimming apart of the shoal Sick fish slowly swimming close to surface Sampling

Sometimes diseased fish are not visible from the top of the cage, therefore it is necessery to get informations from diver. For instance, pseudotuberculosis caused by Photobacterium damselae, subsp. piscicida usually starts with dead fish visible only on the bottom of the net

General provisions on sampling in Mediterranean marine farms  In the case of outbreak it is necessary to collect at least 10 moribund fish and 10 „healthy fish”  Surveillance – there is no EU or OIE listed diseases for the moment, but VNN supposed to be threat to the succesful farming  According to EU 2006/88, article 50.  Mediterranean mariculture should define their threats and articulate possible programmes (VNN, Tenacibaculosis, parasitosis like Ceratothoe oestroides etc.

Infection with Tenacibaculum maritimum Sphaerospora dicentrarchi from intestine of sea bass Ceratothoe oestroides Lernanthropus kroyeri