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aquaculture > sea_lice > Flashcards

sea_lice Flashcards

1
Q

sea lice (sea lous sgl.) is a member of which family?

A

copepodes

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2
Q

what is sea lice?

A

ectoparaiste of many fish species.

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3
Q

on what does sea lice feed on? - what effect has that on the host?

A
  • mucus, skin and blood of fish
  • -> effect on:
  • host osmotic potential,
  • wounds open for infection
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4
Q

name the three sea lice genera

A

caligus
pseudocaligus
lepeophteirus

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5
Q

sea lice is harmful toards human health. true or false?

A

false

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6
Q

all sealice species are specific. true or false

A

false
caligus elogatus: >80 species
lepeoptheiurs salmonis: 3 genera

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7
Q

name two species of sea lice

A 
caligus elongatus 
lepeoptheirus salmonis (l. salmonis)
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8
Q

which sea lice species is the biggest threat for salmon AQC ?
and why?

A

L. salmonis

  • larger than c. elongatus
  • all year round infection
  • favors more sensitive skin areas (head, anal region)
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9
Q

what are the most common hosts for sea lice? L.salmonis

A

species from the salomonidae family:

  • salmo
  • salvelinus
  • oncorhynchus
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10
Q

sea lice: direct or indirect parasite?

A

direct

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11
Q

how many life stages does sea lice have?
name them!
L.salmonis

A 
8
planktonic stages: 
-nauplius 1
-nauplius 2
infective stages 
-copepodid
nonmotile stages 
-chalimus 1
-chalimus 2
(-former 1,2,3,4)
motile stages 
-preadult 1
-preadult 2
- adult male /adult female
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12
Q

the life stages can be divides into two life stages forms. name them?

A 
free-living stages  (nauplius 1&2 and copepodid)
parasitic stages  (rest....)
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13
Q

on what depends the developement time of nauplius 1 on 2?

L.salmonis

A

on temperature

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14
Q

what does postively phototactic mean? which stages of sea lice are postively phototactic?
L.salmonis

A

moving in the direction of light
–> daily vertial migration (rising during day, sinking at night)

  • nauplius copepode stages
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15
Q

what happens at copepode stage?

L.salmonis

A

attaching of the copepode on the fish

=infective stage

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16
Q

how long does copepode stage last?
- waht factor influences the time duration?
L.salmonis

A

2-14 days

-depending on water temperature

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17
Q

chemoattractants play an important role, when finding the “right” host. true or false
L.salmonis

A

true

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18
Q

the positively phototactic behaviour increases the chance to
L.salmonis

A

???

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19
Q

copepodes are better swimmer than nauplii.
true or false?
L.salmonis

A

true

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20
Q

what affcts survival and setlement of copepodes?

L.salmonis

A
  • local water currents
  • temper.
  • salinity
  • light intensity
  • chemoattractants
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21
Q

infection of sea lice has affects on behaviour of salmon. name some
L.salmonis

A
  • muscle twitches
  • rolls
  • bursts
  • jumps
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22
Q

what are the differences accroding moving on the host between the parasitic stages: chalimus stage (1 and 2) and predault stage?
L.salmonis

A

chalimus 1 and 2:
- attached to the host (through frontal filaments)
pre adult:
- louse is mobil –> moves around on the hosts body, prefers heas/anal regions

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23
Q

are female lice or male lice larger?

L.salmonis

A

femals (8-12 mm)

males (5-6 mm)

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24
Q

what does fecundity describe?

L.salmonis

A

mean egg number per string

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25
Q

how many egg strings can female adult lice produce? L.salmonis

A

10-11 pairs

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26
Q

egg strings tend to be longer with….

L.salmonis

A

… with higher fecundity

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27
Q

what is the fecundity values?

A

152 eggs

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28
Q

how long is the genration time of L.salmonis

A

depends on the temperature, the colder the longer

4-9 weeks

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29
Q

at what lif stage does sea lice start eating?

L.salmonis

A
  • nauplii 1&2, copepdodid: live on endogenous food storage–> non feeding

chalimus= first feeding stage

30
Q

how does the site selection of sea lice changes during the life stages?
L.salmonis

A

chalimus :

  • dorsal, pectoral fins
  • around anus

preadult and adult:

  • head
  • dosal surfaces
  • around anus
31
Q

caligus elongatus:

generalist or specialist?

A

generalist ( >80 host species)

32
Q

c elongatus is abigger problem for AQC in southern norway. true or false

A

fals: in northern

33
Q

how many life stages has c. elongatus?

A 
8:
nauplii 1&2
1 copepodid
4chalimi 
1 adult
34
Q

how many degree days does the copepodid stage lasts after infection?
copepodid-chalimus

A

71

35
Q

how many degree days does the chalimus stage lasts after infection?
chalimus - adult

A

234

36
Q

how is the fish affected by the lice c elongatus?

A

lice attaches and feeds on the fish —>
- physical damage :

may lead to osmoregulatory failure and secondary infections

37
Q

what is the deadly limit of a host from c. elongatus?

A

0.75 adult lice/g body weight smolt

38
Q

death of grown salmon due to infection of c.elongtaus is rare. true or false?

A

true

39
Q

what are clinical signs fro an infction by c elongatus?

A
  • skin erosion, open wounds often on the head and back
  • ->- supepidermal haemorrhaging (bleeding under the skin)
  • -> erosin of skin
40
Q

what influences the host suceptibility?

A
  • host stress
  • nutrional status
  • immune system
  • genes
41
Q

when was the first infection of sea lice in norway reported?

A

1960

42
Q

sea lice is a natural parasite and was already found on fishes before industrial AQC.
true or fals?

A

true

43
Q

how salmon be transferred from fresh water systems to salom in cages?

A

through wild salmon which are infected. when they swimm past a salmon farm they can transfer the infection.

also possible the other war around

44
Q

where in norway could the highest infections of sea been observed?

A

møre and Romsdal

Nord-Trøndelag

45
Q

in what stage is the sea lice first infective?

A

copepodid

46
Q

what determines the infectio window of the sea lice?

A

the duration of copepodid
life stage
- depends on water temp.

47
Q

on what deneds the distance a lice can travel?

A

on local water currents

48
Q

on what does the dispersal of sea lice depend on?

A

temp. =time

water currents * time = distance

49
Q

what is the traffic light system ?

A

norway coast divided into 13 zone. each zone will get a red/yellow or green light, dependning on the sea lice infection in this area

50
Q

what is the goal of the traffic light system

A

reducte the impact of sea lice on wild salmon/caged salmon, by regulating biomass production in a zone.

51
Q

how much of the population has to die due to lice infection that the zone is declared as a yellow zone? what is the consequence of the yellow light ?

A

10-30 % of the population

no reduction /increase of biomass in the production zone

52
Q

how much of the population has to die due to lice infection that the zone is declared as a red zone? what is the consequence of the red light ?

A

> 30 % of the population

reduce biomass in production zone

53
Q

how much of the population has to die due to lice infection that the zone is declared as a green zone? what is the consequence of the green light ?

A

less than 10 % of the population

increse biomass in production zone

54
Q

how high have been the costs for sea lice in norwa in 2011?

how is the trend? how high in 2014?

A
  1. 5 billion NOK
    trend: increasing
    2014: doubled: ≈5 billion NOK
55
Q

what is the limit for sealice per fish ?

why?

A

20 adult per fish,

due to the rapid increase of sea lice beyond this point

56
Q

what are the 2 actions to combatt sea lice?

A

precuationary action

treatment actions

57
Q

name some precautionary actions to combatt sea lice.

A
  • cleaner fish
  • selective breeding
  • fallowing
  • vaccines
  • coordinated deployment of fish
58
Q

name some treatment actions to combatt sea lice.

4

A
  1. )medical:
  2. 1 oral or 1.2. bath
    2) mechanical
59
Q

what is “cleaner fish” action?
what is positive, what is negative?
increasing or decresing use?

A

using fishes that feed on the sea lice
–> increasing use

positive: no chemicals, natural
negative: fear of transmitting disease, need cleaner nets

60
Q

what speciesa res used as “cleaner fishes”?

A

lumpfish, wrasse species

61
Q

on what depends “selective breeding” action?
what isthe goal?
how high were the susceptibility difference betw. salmon families?

A

depends on genetic variation in susceptibility to sea lice infection and the heritability of this.

–> breeding for lice resistence

70%

62
Q

name some oral treatment medicaments and the benefits and negatives of oral treatments.

A

SLICE
EKTOBANN

benefits:
- easy to control dosage
- less release in the environment
- less stressfull for the fish

negative:

  • can reduse appetite of the fish
  • expensive when fish is big and more feed is neeede.
63
Q

name some benefits and negatives of bath treatments.

give some example for bath treatment substances.

A

benefits:
- applied quickly
- fisnished in one day

negatives:
- chemicals released into environment
- need to control oxgen level –> add more
stressfull for the fish

  • hydrogenperoxid
  • terapuline
64
Q

what is MFMU?

A

medical free methods without handing

65
Q

hat is MFMH?

A

medical free methods with handling

66
Q

name some MFMH. what
3
need to be done to the salmon lice after the MFMH?

A

thermal heating of seaweter –> lice falls of
- hosing the salmon (abspritzen) (turbulences in the water)
- hosing+brushing
freswater

lice need to be collected and destroyed, to limit reinfection risk

67
Q

name some MFMU treatment.

3

A

cleaner fish
lasers
frehswater treatment in cage ()

68
Q

how does the freswater MFMU treatemnt work?

A

affects iso osmotic balance of the lice (copepodids higher affected than preadult/adult stages)

69
Q

name some preventive techological actions.

A
  • lice skirts
  • snokel cages
  • submergable cages
  • semienclosed cages
  • electrical fences around the cage
70
Q

what is the task force sea lice?

A

collaboration betw. most of the big salmon producing companies in trøndelag and NTNU

aquaculture (14 decks)

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