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Flashcards in Aquatic Ecology final Deck (324)
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31

feed used in BC, 2000

65 million kg
to produce 49million kg farmed fish

32

what happens to feed

20% deposited as feces
unused feed deposited as solid
excretory release of dissolved material

33

chemical components of aquaculture feed

45-65% is Carbon
6-10% is N, 1-2% is P
total system loading unknown

34

whats so important about increased N, P

two most important nutrients responsible fro eutrophication

35

Estimated loading to BCs coastal water from aquaculture

7.1 million kg of C
1.3 million kg of N
236,000kg P
all per year
may not be significant for entire system, but definitely important in enclosed bays

36

how salmon are unlike other 'farm' animals

carnivorous, feed is 45% fishmeal, 25% fish oil

37

cost of producing farm fish

2.8kg wild fish = 1kg farm fish
area required to produce the feed = 40-50,000X production area

38

Amount of PP being used for aquaculture

European industry - ~90% of North Seas's PP
BC - 7.8million ha of ocean (278X area of all terrestrial BC horticulture)

39

what's underneath a fish farm???

black sediment - highly organic material, reductive, lacking oxygen

40

taxa richness vs [sulfide] (µM)

negative linear
appears well correlated, but also a pretty wide spread in the data

41

whats happening with the sulfide

increased Cord -- increased sulfide accumulation-- kill benthic inverts.

42

rockfish near farms

found to have higher Hg content closer to fish farms

43

why rockfish?

not very migratory, good proxy for local condition

44

why higher Hg near fish farms?

oxygen reduction due to C loading = anoxic sediment-- Hg methylated and converted to usable form (methyl mercury)-- accumulates in tissues-- produces neurological effects

45

levels of contaminants in farm produced, store bought, wild salmon

farmed & most of store bought ~ equal in all of the contaminants/carcinogens tested (PCB, dioxin, toxaphene, dieldrin), wild lower
some store bought appears to be wild but more is farmed

46

fish utilization and supply (excluding China), trend

1950-2002
population linear increasing
food supply non changing

47

changes in fishmeal use, 1988-2002

1988: Poultry 59%, aquaculture 10%, pigs 20%
2002: poultry 22%, aquaculture 46%, pigs 25%

48

what are poultry being fed now

bluegreen algae (more deeply coloured yolk, carotenoids)

49

fish oil use

1990: edible 76%, aquaculture 16%, industrial 8%
2002: edible 14%, aquaculture 81%, industrial 5%

50

Other sources of fish feed

by-catch
fish processing by-products
plant products
livestock by-products

51

Canada salmon feed

lowest fishmeal and oil inclusion rate

52

SA fish feed

41% of all fish used in feed, including: Anchoret, Chilean jack mackerel, South American pilchard
very important low trophic level fishes!!

53

top marine capture, 2002

anchoveta (9.7mt)
pollock (2.7mt)
tuna (2.0mt)
capelin (2.0mt)
herring (1.9mt)

54

changes in salmon fishmeal/fish oil use

fishmeal +185%
fish oil +577%

55

changes in carp fishmeal/fish oil use

fishmeal 750%
oil 70%

56

changes in crustacean fishmeal/oil use

fishmeal 1363% increase
fish oil 2660% increase!

57

overexploited species for fish feed

Peruvian anchovy- 6.2mt harvested 2003, recovering, overfished
Chilean jack mackerel- 1.7mt harvest 2003, fully fished, overfished
up to 11 species in this list are fully fished, unsustainable!

58

SA harvest of feed fish

1960-70's exploit anchoveta-- collapse-- SA pilchard takes over niche-- exploit them-- collapse-- chilean jack mackerel moves in..

59

natural cause of population decline in fish species

El Niño- huge decrease 1998

60

capture-reduction

how much is caught relative to time vessel spends out (? maybe) .. lowest in El Niño yrs