Term
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Definition
| animal with body temp that varies based on its environmental temperature |
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Term
| Why is raising fish different from raising land animals, in terms of their growth cycle? |
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Definition
they have different life stages, each with different anatomy, physiology and nutritional requirements
lots to accomodate! |
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Term
| What type of thermoregulation describes fish and crustaeans? |
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Definition
they are ectotherms
-internal heat production has minimal effect on body temperature |
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Term
| How is nitrogen waste handled in the fish? |
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Definition
they are ammoniothelic
(soluble ammonia is excreted to remove excess N from body) |
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Term
| Describe how CO2 & NH3 are excreted |
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Definition
-[NH3] and [CO2] in blood is high, so they move across gill epithelium to lower concentration in boundary water layer
[CO2] creates acidic environment, promotes NH4 production
-NH3 converted to NH4+ while CO2 to HCO3-
-flow out into bulk water environment |
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Term
True or False
fish do not produce urea |
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Definition
| false, they do but <15% of N is excreted as urea, while >80% excreted as ammonia |
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Term
| What is the major route of excretion of ammonia in fish? |
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Definition
| branchial (through gills) |
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Term
| How does water temperature affect metabolic rate? |
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Definition
| as temp increases so does basal metabolism, within an optimal range |
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Term
| Is basal metabolism of fish greater or lesser than homeotherms? |
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Definition
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Term
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Definition
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Term
| Compare the exo vs endo skeleton (7) |
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Definition
EXO
-highly protective
-good leverage
-heavy
-limits size
-growth occurs in bouts
-vulnerable during molting
-high regneration potential
ENDO
opposites |
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Term
| What does it mean to describe fish growth as 'plastic' |
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Definition
fish don't have a finite size, can potentially grow for as long as they life if conditions are right
can survive starvation for long periods and resume growth when conditions become good again |
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Term
| Why are fish so efficient at waste excretion and oxygen intake? |
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Definition
| epithelium between blood & external environment is only 1 cell thick, very easy for waste to cross the gills and exit, oxygen to come in |
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Term
| If a growth curve shows several spikes, with a dip in between each one, what causes the cycles of growth and 'degrowth'? WHy can't this model be used for all fish? |
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Definition
successions of seasons, winter is the dip and spring is the spike
areas without seasons won't depict this accurately |
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Term
| What are the problems associated with mathematical modeling of a growth curve? |
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Definition
Several factors affect growth:
disease status
genetic potential
water temperature
food availability
Can't account for all these in one model, so need to determine the effect of each individually |
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Term
| What effect does a 'masking' variable have on growth? |
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Definition
masks the true growth potential of the animal.
e.g. salinity of water |
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Term
| Wat effect does a 'limiting' variable have on growth? |
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Definition
restricts the animal from reaching its growth potential
e.g. oxygen, amount being fed |
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Term
| Wat effect does a 'directive' variable have on growth? |
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Definition
Influences the growth of the animal
e.g. keeping lights on to 'trick' animal into thinking it is spring |
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Term
| What is the growth potential hypothesis? |
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Definition
| animals have a predefined growth trajectory which can be manipulated through management e.g. photoperiod, hormones, water temperature |
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Term
| Why would we want to carry out mathematical modelling of fish growth? (4) |
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Definition
1. To predict growth in future (to determine production, time to market weight etc)
2. Intrapolate growth between sampling periods (can look back at data and troubleshoot)
3. Compare different lots, strains, sites, farms etc
4. Develop production plans based on different scenarious |
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Term
| A growth curve that looks like a staircase is modeling what type of aquatic animal? |
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Definition
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Term
| What is the most widely used growth model? Is it accurate? |
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Definition
specific growth rate (SGR)
no! |
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Term
| Intrapolation using the SGR model often ______ growth rate, while ADG ______ growth rate. |
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Definition
underestimates
overestimates |
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Term
| Extrapolation using the SGR model often ______ growth rate, while ADG ______ growth rate. |
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Definition
overestimates
underestimates |
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Term
| What are the characteristics of a suitable growth model? |
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Definition
1. Can accurately describe trajectory for both intrapolation and extrapolation at constant temperature
2. Accurately describe trajectory at varying temperatures
3. easy to compute |
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Term
| What is the relationship between water temperature and daily growth? |
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Definition
| increase proportionally in response to temp |
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Term
| The _____ accounts for a large proportion of a fish's weight |
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Definition
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Term
| How does body composition of fish change as they grow? |
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Definition
initially high water content decreases with time
lipids & protein stores increase with time based on diet
vit/min content fairly stable |
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Term
| Do protein stores also store water? |
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Definition
yes
protein is scaffolding, water fills the spaces |
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Term
| Describe the AA composition of fish |
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Definition
| Fish species are made up of different proteins with varying AA profiles, although very similar |
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Term
| What effect does neutral lipid deposition have on live weight? |
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Definition
| non - it replaces water in cells |
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Term
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Definition
| energy lipid stores (not structural lipids like in cell mmbs) |
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Term
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Definition
Mostly.
-what we consume is the building blocks for our body structures
-many of the building blocks/components cannot be made from scratch, and have no substitutions
-so need to eat food that supports what we need |
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