Issues for fish farming
- Sustainability
- Fish escaping
- Pollution
- Eco- efficiency
- Disease
Nutritional value of fish
- highly disgestable protein (15- 20g/ 100g of fish)
[rich in essential amino acid]
[Protein break down as absorpable peptides, maybe bioactive and enhance immunity] - Fish oil ( 20% in oily fish; 1-2 % in lean fish)
[extracted- long chain omega 3: eicosapentanenoic (EPA) & docosahexaenoic (DHA)] - Vitamin A, E, D & B
- minerals: rich sources of iodine and selenium, low level iron ( but effectively absorpable), calcium and phosphorus (from soft fish bones in salmon, sadines etc)
UK fish consumption 2000- 05
20% more total fish consumption 100% more shell fish consumption 25% more oily fish consumption Consumption below global average (20Kg) 75% in UK do not eat fish (www.seafish.org)
Fish consumed in UK
(x1000 T)
- Tuna 77000
- Salmon 50182
- Cod 48775
- Prawns 33023
- Haddock 23015
Fish spoiled quickily if ________, because_______
it’s not chilled
continually enzyme activity (autolysis) & bacteria
In fish spoilage, protein breaks down to
peptide, amino acids and amines - especially cadaverine & histamine
Bacteria build up in fish spoilage can
produce toxin within the bacteria cell wall (endotoxin)
Enzyme in fish optimal activity temperature
the typical environmental temperature
To reduce enzyme activity in fish
to drop the temperature lower than the environmental temperature whether they come from warm or cold water
Vitamin A in fish
in the form of more assimilated retinol needed for vision, reproduction and development
Vitamin D in fish
in the form of D3 (cholecalciferol) which promotes absorption of calcium and phosphorus
Vitamin E in fish
an antioxidant which protects PUFAs and low density cholestrol from oxidation by free radicals
Vitamin B complex in fish
includes vit B12, thiamine, riboflavin & pyridoxine. Essential in carbohydrate metabolism. B12 needed for formation of red blood cell
Shell fish has rich minerals of
zinc & iron
Lipid content in fish depends on
- types of fish
- fish feed
- Time of year
Factors of high carcass fat
- low activity in farmed fish
- high energy feed
Salmon lipid content
vary between 8 - 20%
even higher in bigger fish
Fish oil are high in
- long chain omega 3 : eicosapentaenoic acid (EPA) & docosahexaenoic acid (DHA)
- some monounsaturated and saturated fatty acids
fish lipid content reflects on __________
fish feed
All marine feeds gives high content of
EPA eicosapentaenoic acid
DHA docosahexaenoic acid
Substitution of fish feed with vegatable oil tend to lower the
fish lipid content of eicosapentaenoic and docosahexaenoic, especially the DHA and increase omega 6
Demersal fish have ______ lipid content in _______
store lipid in _______
eg. cod, haddock
low lipid content in muscle
and store lipid in liver
Lipid in muscle are rich in
long chain omega 3, with significant amount in phospholipid form
Fish oil effects in human
- Brain development
- Foetus brain growth & development - ME & Central nervous system [ LCPUFA (DHA!!) , iodine & trace elements] [Ratio up to 15:1]
- Immunity response - eczema, asthma
- Evolved with littoral marine and lacustrine food chains
- Poor conversion of linoleic and linolenic acid to LC-PUFAs
- Placenta selectively transfers LC-PUFAs: biomagnification
Role of EPA and DHA
- Produce eicosanoids (cell messengers) in cell membrane, include: prostracyclins and thromboxanes > affecting the contraction of blood vessels and stickiness of platelets; leukotrienes > reduce inflammation
- reduce thrombosis - blood clot blocks an arteries> avoid stroke
- reduce irregular heartbeats (arrhythmias)
Omega 3 deficiency
- Coronary heart disease and stroke
- EFA deficiency in infancy and associated retinal and brain damage
- Auto-immune disorders (e.g. asthma, eczma, psoriasis)
- Crohn’s disease
- Mild hypertension
- Rheumatoid arthritis
Fish/Fish Oil and Cardiovascular Protection
- Omega-3 (EPA + DHA) are components of phospholipids in all cell walls throughout the body
- improve membrane function
- reduce blood aggregation) > reduce clotting tendency
- Blood pressure is decreased
- Three large controlled trials with 32,000 participants showed a 19% to 45% reduction of cardiovascular events as a result of as supplements of EPA plus DHA
- Epidemiological studies consistently shown a significant inverse relationship between coronary arterial disease (CAD) and fish intake.
- One fishmeal per week was associated with a 15% reduction in ChD risk, five or more were associated with a 40%
¹(Lee J L et al, 2008)
Fish and Brain/Neurological Development
- The brain is the fatty organ containing a high proportion of EPA & DHA, especially DHA
- Nerves and eyes too have a high content of EPA & DHA
- Body synthesis of these fatty acids is poor
- Fish can provide a rich source of the PUFA
- Human milk contains small amounts of DHA. Fish is recommended, especially in pregnancy and lactation. Foetal development is improved by so doing
- Continued feeding of some form of fish during infancy improves mental development (cognitive function)
- Fish reduces incidence of attention deficit hyperactive disorder. It can help in cases of dyslexia
Deficiency of omega-3 LC-PUFA linked to:-
- Reduced cognitive function
- Reduced visual function
- Attention deficit
- Hyperactivity disorders
- Dyslexia
- Senile dementia
- Clinical depression
- Bipolar disorder
- Schizophrenia
Fish Consumption and Mental Development
- can reduce incidence or severity of depression and schizophrenia; also help in some cases of Alzheimer’s disease
- believed to improve synapase plasticity in the brain, improving neuron connections (signaling)
FISH INTAKE AND POST-NATAL DEPRESSION
Study of 14,500 pregnant women in last trimester to 8 months after birth
High intakes-consumed fish twice or three times a week
High fish eaters had half the incidence of major depressive disorders
FISH FATTY ACIDS MAKE BETTER PRISONERS
- Study at Aylesbury Juvenile Jail, involved 230 prisoners
- Half received a multi-vitamin supplement plus EPA and DHA; other half got vegetable oil
- Dramatic reduction in bad behaviour of EPA/DHA consumers
(Bernard Gesch, Oxford University)
GLOBAL NEEDS FOR EPA + DHA
Global population 7 billion; 1 billion eat fish
Assuming remaining 6 billion should receive EU suggested amount of 250mg/day for normal circulatory, heart and cognitive function > Need 91g / person/ yr
Globally would need 546,000t fish oil or increased fish supply. ( increase over half of now world fish oil production) Is 250 mg/person/day realistic?
CLAIMS ALLOWED BY EU FOR BENEFITS OF EPA + DHA
DHA:
- Contributes to normal brain function, brain development of foetus and breast-fed infants, vision and visual development of infants to 12 months of age, normal development of eye of foetus and breast-fed infants.
DHA + EPA:
- Contribute to normal function of heart
( EU 432/2012 and 440/2011)