Case 5: Fish

Question 1

What does the increasing demand for food fish from aquaculture require?

Answer 1

intensive farming

Question 2

What is intensive farming?

Answer 2

feed is the main input and takes a substantial share of the total production cost

Question 3

What is essential in terms of feeding to max growth rate in fish?

Answer 3

Feeding fish to their voluntary feed intake level

Question 4

What is aquaculture?

Answer 4

Cultivation of aquatic organisms under controlled conditions, individual or corporate ownership of cultured stocks

Question 5

What is mariculture?

Answer 5

aquaculture in practiced marine environments

Question 6

What is marine biotechnology?

Answer 6

farming of marine organisms, for non-food purposes including extraction of chemical or pharmacological products

Question 7

What is a capture fishery?

Answer 7

the capture of aquatic organisms from their natural environment

Question 8

What is the basic unit in aquaculture and capture fisheries?

Answer 8

stock/population

Question 9

What is the difference between aquaculture and capture fisheries?

Answer 9

capture fisheries the fisherman can only make decisions relating to:
fishing area, period, method, fished on a common resource

aquaculture can exert a level of control including:
genetics, larval rearing, live food culture, reproduction, disinfection, feeds/feeding, engineering, health care/disease, husbandry, stocking density, water quality management, algae and bacteria management

Question 10

What are some special characteristics of fish?

Answer 10

cold blooded (poikilothermic) animals
difficulty using carbs, principle energy is from fats
gas exchange through gills or skin diffusion
many different modes of reproduction
most animals derive structure from calcareous materials

Question 11

What is the global per capita fish consumption per year?

Answer 11

16.6 kg

Question 12

What is fish an important source of for us?

Answer 12

omega 3 fatty acids such as linolic acid, linolenic acid, arachdonic acid, eicosapentaenoic acid, docosahexaeoic acid, contribute to stress resistance, immunity, neural activity, brain function and ion balance

Question 13

What is voluntary feed intake under the control of?

Answer 13

central feeding system located in the brain, with hunger and satiation signals being transmitted through complex networking of peripheral neural and humoral signals

Question 14

In the short term, what is feed intake controlled by in fish?

Answer 14

It’s stomach volume and gastrointestinal emptying rate

Question 15

What happens after a period of feed, deprivation, in fish?

Answer 15

The amount of feed intake often exceeds the normal level of intake after a period of feed deprivation, which implies flexibility in the gut volume

Question 16

What are the environmental factors that gastrointestinal motility depends on?

Answer 16

Water temperature increases the rate of evacuation

Question 17

what will happen to physical limitations of the gut, long-term in fish?

Answer 17

The physical limitation of the gut will have minimal influence on the feed intake in fish

Question 18

What kind of role does protein play in fish’s diet?

Answer 18

Protein plays an important role in energy supply in the fish. The changes in the amount of dietary protein and the composition of amino acids affects feed and taken various fish species.

Question 19

What happens if the energy demand for maintenance and growth of fish is presumed to be constant?

Answer 19

The fish will maintain a similar energy intake when fed diets vary and macro nutrient composition

Question 20

What are some characteristics about oxygen in water versus oxygen in air?

Answer 20

The amount of oxygen and water is 20 times less than the air. The amount of dissolved oxygen and water fluctuates greatly, and is being the prime limiting factor for survival, feeding, growth and reproduction in water-breathing fish.

Question 21

What is the trend for feed intake and oxygen levels in water?

Answer 21

Feed and take decreases linearly with decreasing water, oxygen levels

Question 22

What is incipient dissolved oxygen?

Answer 22

The minimum concentration of dissolved oxygen in water at which the physiological oxygen demand for fish for feed and limiting

Question 23

How does oxidative metabolism do to food energy intake affect the animal?

Answer 23

It has negative effects in the long term this could lead to ageing

Question 24

What is active metabolism?

Answer 24

The maximum amount of oxygen that a fish can obtain from water for aerobic metabolism

Question 25

What is routine metabolism?

Answer 25

The minimum oxygen consumption needed to sustain the physiological activity of an unfed fish

Question 26

what is the oxygen limitation theory?

Answer 26

The maximum rate of feed intake of fish is related to the capacity to deliver oxygen for feed processing at non-limiting water oxygen levels.

Question 27

Why is damage due to oxidative metabolism assumed to be greater in fish?

Answer 27

Due to the presence of high-level of poly and saturated fatty acids that are susceptible to oxidation thus a fish should have a desired setpoint value of oxygen consumption rate to perform all of its functions, including feeding

Question 28

What is one of the most limiting environmental factors in aqua culture?

Answer 28

The supply of oxygen

Question 29

What happens at low water oxygen level in aquaculture

Answer 29

Limits the feed and take a fish, thereby reducing the growth

Question 30

What is a common practice to maintain normal oxygen levels in the water in intensive aqua culture?

Answer 30

Maintain a continuous supply of oxygen through aeration and oxygenation

Question 31

What is the minimum concentration of dissolved oxygen needed to meet oxygen demand for feed intake?

Answer 31

It depends on the size of the fish and the nutrient profile of the diet

Question 32

What are some other factors that affect the oxygen carrying capacity in fish?

Answer 32

Accumulation of metabolites CO2 and nitrogenous compounds in water of intensive aqua culture systems. This might affect the feed and take a fish and the oxygen carrying capacity.

Question 33

How does most fish farming occur in terms of housing structures?

Answer 33

Culture systems, like ponds and cages, which are parental changes and temperature and light, which might affect water dissolved oxygen levels

Question 34

How will increasing the number of feeding sessions or feeding continuously affect oxygen consumption of fish

Answer 34

It will lower the peak oxygen consumption, which might reduce the impact of dietary macro nutrients on the within day, variation, in feed intake

Question 35

What is an issue for wild aquatic ecosystems in terms of feeding

Answer 35

Increasing occurrence of hypoxia and marine waters due to notification and climate change might shift the energy flow by disturbing the food web. It affects the abundance diverse and catch a fish. It also changes the diet of fish due to structural shifts and food availability.

Question 36

What is a meristic character?

Answer 36

Countable features of fishes anatomy

Question 37

What is a metric character?

Answer 37

Measurable features of a vicious body expressed in linear dimensions or ratios

Question 38

List the anatomy of the fish

Answer 38

See page 6 of case five practical manual

Question 39

List the general components of the digestive system for the catfish

Answer 39

Jaw, rasp, plates, esophagus, stomach, pyloric, valve, gut, midgut, hind gut, gonads, anus, urogenital, papilla, ventral, Mentry, liver, gallbladder, pancreas, see page 15 and16

Question 40

How does the respiratory system work in fish?

Answer 40

Only a few cells can store oxygen so they must be continuously supplied at the same time carbon dioxide produced as waste and cellular metabolism must be released into the environment. Gas exchange occurs through diffusion where gas molecules move a region of higher partial pressure to region of lower, partial pressure, oxygen and carbon dioxide diffuse across an animals respiratory surfaces which are thin, moist cell membranes, exposed t.

Question 41

What does ficks law imply?

Answer 41

That the rate of diffusion will decrease as the thickness of the respiratory membrane increases

Question 42

What is the function of the gills?

Answer 42

Out growth of the body wall that increased the surface area for gas exchange gills may also transport salt and serve and filter feeding and they are the main sites of waste disposal and many aquatic animals

Question 43

How does water pass through the gills?

Answer 43

Water enters the mouth and is pushed out through gills slits, which open between four-gill arches located on the sidewalk of the faring. Each gill arch carries a pair of feather like gill filaments on the lateral side and cartilage projections. Also called Gill Rakers on the medial side, filament tips from adjacent arches, interlock to form a sieve, through which water from the pharynx passes, each filament bears, thin and flat, lamellae where gas exchange occur special cells of the produce mucus that coats, the service to prevent invasion of microorganisms

Question 44

What is the function of the lamellae?

Answer 44

Greatly increase the surface area for gas exchange

Question 45

what type of heart do fish possess?

Answer 45

For chambered heart