Fish Flashcards
Name the steps in fish processing
- Gutting and deheading
- Desliming
- Weighing
- Filleting
- Trimming
- Pinbone removal
- Skinning
- Fillet washing
- Grading
What is Clonorchis Sinensis? When is its infective stage?
A trematode
The infective stage is metacercaria, found in the muscle and subcut tissue
Where is Clonorchis Sinensis found in people?
Bile ducts
What is the most commn species of Diphyllobothrium spp. that infects humans?
D. Latum
Where is D. Latum found in humans?
The mucosa of the ileum and jejunum - treat with praziquantel
What is Mycobacterium marin?
A resistant bacteria found in ornamental fish - aquarists finger
Name the common bacteria associated with consuming bivalves
Salmonella spp Shigella spp. Vibrio parahaemolyticus Vibrio vulnificus Campylobacter spp. Listeria
What chemicals are associated with bivalves?
Heavy metals including mercury, cadmium and lead
What organics are associated with bivalves?
Dioxins, Polychlorinated Biphenyls, Polycyclic aromatic hydrocarbons (PAH’s) and pesticides
What are the two most significant species of vibrio in bivalves?
V. Vulnificus
V. Parahaemolyticus
How does v. Vulnificus infect?
Lives in warm seawater and can infect via open wounds eating raw oysters
What does v. parahaemolyticus cause?
Gastroenteritis, readily detected in Uk seafood
What does v. parahaemolyticus cause?
Gastroenteritis, readily detected in UK seafood
How do algal toxins infect people?
phytoplankton produce the toxins which are filtered by bivalves and accumulate in their flesh
Who carries out the monitoring of contamination in seafood?
Centre for environment, fisheries and aquaculture science (CEFAS)
Under European Union food hygiene legislation, what products require freeing before consumption?
Sushi fish and cold smoked, finish or molluscs destined to be consumed lightly cooked or raw
How long must fishery products be frozen for?
- 20’C for not less than 24h
- 35’C for not less than 15h
What are the exceptions to freezing of fish?
If the fish is cooked before consumption at a core temp of over 60’C for 1 min
Frozen fish products stored at -18’C for 4 days
Wild catches authorised by the FSA (currently no exemptions in the UK)
Farmed systems free from viable parasites
What happens to the water in good shellfish farms?
It is passed under a UV light to kill microorganisms (this isn’t great for killing viruses though)
Inshore waters are graded from A-D, what does grade A mean?
Molluscs contain less than 250 E.Coli per 100g of flesh- fit for human consumption
Inshore waters are graded from A-D, what does grade B mean?
90% of sampled molluscs have up to 4,600 E.coli per 100g of flesh
10% of sampled m have up to 46,000 E.Coli per 100g
Inshore waters are graded from A-D, what does grade C mean?
<46,000 E.Coli per 100g
Inshore waters are graded from A-D, what does grade D mean?
> 46,000 E.Coli per 100g
What are finfish?
Marine: Atlantic salmon, cod, halibut
Freshwater: Rainbow trout, brown trout, carp
What do mussels feed on?
natural plankton in the water - no additional food is added
In suspended culture how long do the mussels grow for?
18-24 m
How do you set up a fish farm in Scotland?
Permission from the local regional council, Marine license from marine Scotland and a discharge licence from Scottish environment protection agency
What are the EU end product standards for bivalves?
They must be: Alive Fresh and in good condition Contain inter-valvular fluid Respond to a sharp tap Meet specified bacterial and toxin standards
What is the largest group of fish consuming fish food?
carp, second is salmonids
How many UK salmon farms are there?
320
What are the top 3 salmon producing countries?
Norway, Chile and scotland
What are juvenile salmon called?
Smolts
When are the smolts moved to seawater cages?
Smolts are produced at specialised freshwater hatcheries and are transferred to seawater cages at six months, they are harvested at +2y
How heavy are salmon when they are harvested?
2-3kg
Are trout farmed in fresh or seawater?
Fresh
When are trout harvested?
300-400g at 7-9 months
What are juvenile trout called?
Fingerlings
Why are all rainbow trout stock female?
They can grow to the required size without reaching sexual maturity. If they reach sexual maturity their growth will slow and they will loose condition around spawning time
What is Triploidy?
Shocking eggs of trout to make them sterile so they can grow to over 400g, good if you want to stock the rainbow trout in a river and don’t want them to mate with the local brown trout
Overcrowding fish can result in what?
Canabalism
What are lepeophtheirus salmonids?
Salmon sea lice - most significant fish parasite
How can sea lice be controlled?
Cleaner fish and medicines when necessary
What causes salmon pancreas disease?
Is there a vaccine?
Salmon alphavirus, it affects salmon and rainbow trout in seawater systems.
Yes
What is salmonid rickettsial septicaemia?
SRS is an intracellular bacteria
What causes infectious pancreatic necrosis?
IPN is caused by a virus
Can get vaccines and resistant fish
HSMI often affects fish in the first year of seawater, what is it?
Heart and skeletal muscle inflammation
What is ISA?
Infectious salmon anaemia, a virus
What is gill disease?
A general term to describe pathology of the gills in seawater fish
What points are important to consider in fish farming systems?
O2 and nitrogenous waste disposal
Disposing of water with residues
What can you use to asses water quality?
Dissolved oxygen (DO)
Dissolved solids
Ammonia
Higher water flow can lead to what?
Higher stocking densities
How can we mitigate the environmental impact of fish farming?
Careful water use and thoughtful water return
Prevent escapees
Appropriate pathogen control
