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Define Fish.
- Fish refers to the vertibrate and invertibrate animals that inhabit the aquatic habitat
- a distinct feature is that they respire via gils
- term also used to refer to the parts of these animals that we use as food
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what is a distinct feature of fish?
they respire via gils
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Fish are an excellent source of which nutrients?
- protein
- fat (essential FAs)
- vitamins (B2, B6, B12, C, A, D)
- minerals (Ca, P, Mg, Fe, Zn, Se, I)
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What is the world fish catch in millions of tons?
>90 million tons
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What are the leading fish producing and exporting countries?
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China's fish produciton bas been increasing. From1990- 2000 production has tripled, why?
sophisticated harvesting methods
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What precent of fish captured will be used for food?
75-85%
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Why will fish production increase?
- growing populations, fish is a major source of animal protein especially in developing countries
- health benefits of fish vs. red meat
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About how many fish species are known? What precent of the species are consumed as food?
- ~35,000 species known
- 75-80% are consumed as food
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What are the different types of shell fish?
- crustacia
- molluscs
- echinoderms
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What are some examples of crustacia (shell fish)
- crabs
- lobsters
- shrimp
- crayfish
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what are the different types of molluscs (shell fish)
- gastropods
- cephalopods
- Bivalves
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what are some examples of echinoderms (shell fish)
- seaurchin
- seacucumber
- starfish
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What are some examples of gastropods (moluscs, shell fish)
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What are some examples of cephalopods (moluscs, shell fish)
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What are some examples of bivalves(moluscs, shell fish)
- oysters
- clams
- scallops
- muscles
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What are true fish?
- tend to have a torpido/elliptical shape
- boney: cod, talipia, salmon
- cartilaginous: sharks, rays, skates
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Give examples of the different ranges of flavor of fish.
- mild flavor: sole, flounder, hoki, hake, halibut
- moderate: cod, lobster, scallops, oyster
- intense flavor: salmon, tuna, mackerel
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Give some examples of the different ranges of texture between fish species.
- soft or delicate: anchovies, bass, porgy, herring, hake, sea urchins
- medium: cod, salmon, tilopia, snapper, shrimp
- firmer: catfish, dogfish, strugeon, tuna, scallops, lobster
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What are Piokilotherms?
- cold blooded
- tend to maintain body temperature within 1°C of the ambient water temperature
- shell fish and true fish
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what are endotherms?
- have a body temperature much higher then ambient temperature ~20°C
- white shark, sturgeon, tuna
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What % of fish are eaten fresh?
~22%
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What % of fish are frozen?
~24%
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What % of fish are canned?
~13%
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What % of fish are smoked/salted and dried marinated?
~11%
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What are non-food uses of fish?
- fish meal
- fish oil
- bait
- fertilizers
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What are some trash fish and why?
- Herring (bones)
- Mackerel (color and fat content)
- Tuna (bones)
- still have good nutritional value though
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What are health benefits of fish?
- nutritive quality
- DHA (doccohexonic acid) brain lipid useful for brain development and CV system function- good for lowering blood CH
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What are some hazards of fish?
- heavy metals (Pb, Hg, Cd, As)
- Fish allergens
- Toxins
- Biogenic amines
- parasites
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What are some of the effects of heavy metals?
- nausea
- vomiting
- metallic taste in your mouth
- renal degeneration
- a variety of cancers
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What is the major allergic protein in fish?
parvalburnin
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What are examples of biological amines? What fish are they found in high levels in?
- His (Histidine --HO--> Histamine)
- Tyr (Tyrosine --TO--> Tyramine)
Tuna, mackerel, herring
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What are the negative health effects of microalgea on shell fish?
- microalgea release various metabolites such as domic acids that are abs. by the shellfish
- when the shellfish are consumed may cause health hazards
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What fish is particularly prone to parasites?
What do these parasites do?
- Alaskan Pollock
- parasites release proteases that make the structure soft
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T or F
proximate composition is similar for true fish and shell fish
T
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Why is there greater variation in fish composition then beef?
variation is due to species difference, season of harvest, diet, nutritional status, sex, age, etc.
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What is high protein fish?
- protein content ~28%
- anchovis
- cod
- tilapia
- snapper
- salmon
- halibut
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What are low protein fish?
- ~6%
- catfish
- muscles
- oyster
- flounder
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What is gout?
gout - protein --> uric acid --> crystallizes in joints must avoid high protein food
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What are the seasonal variation in Herring?
- protein content tends to be uniform throughout the year
- in the summer months when fish is actively feeding fat content is much higher
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What are the seasonal variation in Mackeral?
- protein content stays uniform throughout the different seasons
- in the spawning season fat content declines b/c the reserves are used up for energy
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What are some high fat fish?
- mackerel
- herring
- sardines
- salmon
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Where do high fat fish tend to swim?
- swim closer to the surface
- pelagic
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Where is the fat in high fat fish stored?
fat tends to be deposited in the muscle and around the belly cavity
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What is the fat content in low fat fish?
3-28%
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Where is the fat stored in low fat fish?
in the liver
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what are some low fat fish?
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Where do low fat fish swim?
- swim closer to the bottom of the ocean
- demersal fish
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What is the chemical composition of fish closely related to?
- intake
- migratory behavior
- sex
- age
- spawning
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What are the two layers of fish skin?
- outter epidermis
- inner epidermis
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What are the characteristics of the outer epidermis?
- higher moisture content
- PL and mucosal cells
- numerous gland cells that produce the Mucopolysaccharides
- rich mucous responsible for the slimy surface
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What are characteristics of the slime produced by the outer epidermis.
- mainly micropolysaccharides
- makes them difficult to catch- defense
- makes hard for microorganisms to attack
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