sea_lice Flashcards
sea lice (sea lous sgl.) is a member of which family?
copepodes
what is sea lice?
ectoparaiste of many fish species.
on what does sea lice feed on? - what effect has that on the host?
- mucus, skin and blood of fish
- -> effect on:
- host osmotic potential,
- wounds open for infection
name the three sea lice genera
caligus
pseudocaligus
lepeophteirus
sea lice is harmful toards human health. true or false?
false
all sealice species are specific. true or false
false
caligus elogatus: >80 species
lepeoptheiurs salmonis: 3 genera
name two species of sea lice
caligus elongatus lepeoptheirus salmonis (l. salmonis)
which sea lice species is the biggest threat for salmon AQC ?
and why?
L. salmonis
- larger than c. elongatus
- all year round infection
- favors more sensitive skin areas (head, anal region)
what are the most common hosts for sea lice? L.salmonis
species from the salomonidae family:
- salmo
- salvelinus
- oncorhynchus
sea lice: direct or indirect parasite?
direct
how many life stages does sea lice have?
name them!
L.salmonis
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
the life stages can be divides into two life stages forms. name them?
free-living stages (nauplius 1&2 and copepodid) parasitic stages (rest....)
on what depends the developement time of nauplius 1 on 2?
L.salmonis
on temperature
what does postively phototactic mean? which stages of sea lice are postively phototactic?
L.salmonis
moving in the direction of light
–> daily vertial migration (rising during day, sinking at night)
- nauplius copepode stages
what happens at copepode stage?
L.salmonis
attaching of the copepode on the fish
=infective stage
how long does copepode stage last?
- waht factor influences the time duration?
L.salmonis
2-14 days
-depending on water temperature
chemoattractants play an important role, when finding the “right” host. true or false
L.salmonis
true
the positively phototactic behaviour increases the chance to
L.salmonis
???
copepodes are better swimmer than nauplii.
true or false?
L.salmonis
true
what affcts survival and setlement of copepodes?
L.salmonis
- local water currents
- temper.
- salinity
- light intensity
- chemoattractants
infection of sea lice has affects on behaviour of salmon. name some
L.salmonis
- muscle twitches
- rolls
- bursts
- jumps
what are the differences accroding moving on the host between the parasitic stages: chalimus stage (1 and 2) and predault stage?
L.salmonis
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
are female lice or male lice larger?
L.salmonis
femals (8-12 mm)
males (5-6 mm)
what does fecundity describe?
L.salmonis
mean egg number per string
how many egg strings can female adult lice produce? L.salmonis
10-11 pairs
egg strings tend to be longer with….
L.salmonis
… with higher fecundity
what is the fecundity values?
152 eggs
how long is the genration time of L.salmonis
depends on the temperature, the colder the longer
4-9 weeks
at what lif stage does sea lice start eating?
L.salmonis
- nauplii 1&2, copepdodid: live on endogenous food storage–> non feeding
chalimus= first feeding stage
how does the site selection of sea lice changes during the life stages?
L.salmonis
chalimus :
- dorsal, pectoral fins
- around anus
preadult and adult:
- head
- dosal surfaces
- around anus
caligus elongatus:
generalist or specialist?
generalist ( >80 host species)
c elongatus is abigger problem for AQC in southern norway. true or false
fals: in northern
how many life stages has c. elongatus?
8: nauplii 1&2 1 copepodid 4chalimi 1 adult
how many degree days does the copepodid stage lasts after infection?
copepodid-chalimus
71
how many degree days does the chalimus stage lasts after infection?
chalimus - adult
234
how is the fish affected by the lice c elongatus?
lice attaches and feeds on the fish —>
- physical damage :
may lead to osmoregulatory failure and secondary infections
what is the deadly limit of a host from c. elongatus?
0.75 adult lice/g body weight smolt
death of grown salmon due to infection of c.elongtaus is rare. true or false?
true
what are clinical signs fro an infction by c elongatus?
- skin erosion, open wounds often on the head and back
- ->- supepidermal haemorrhaging (bleeding under the skin)
- -> erosin of skin
what influences the host suceptibility?
- host stress
- nutrional status
- immune system
- genes
when was the first infection of sea lice in norway reported?
1960
sea lice is a natural parasite and was already found on fishes before industrial AQC.
true or fals?
true
how salmon be transferred from fresh water systems to salom in cages?
through wild salmon which are infected. when they swimm past a salmon farm they can transfer the infection.
also possible the other war around
where in norway could the highest infections of sea been observed?
møre and Romsdal
Nord-Trøndelag
in what stage is the sea lice first infective?
copepodid
what determines the infectio window of the sea lice?
the duration of copepodid
life stage
- depends on water temp.
on what deneds the distance a lice can travel?
on local water currents
on what does the dispersal of sea lice depend on?
temp. =time
water currents * time = distance
what is the traffic light system ?
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
what is the goal of the traffic light system
reducte the impact of sea lice on wild salmon/caged salmon, by regulating biomass production in a zone.
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 ?
10-30 % of the population
no reduction /increase of biomass in the production zone
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 ?
> 30 % of the population
reduce biomass in production zone
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 ?
less than 10 % of the population
increse biomass in production zone
how high have been the costs for sea lice in norwa in 2011?
how is the trend? how high in 2014?
- 5 billion NOK
trend: increasing
2014: doubled: ≈5 billion NOK
what is the limit for sealice per fish ?
why?
20 adult per fish,
due to the rapid increase of sea lice beyond this point
what are the 2 actions to combatt sea lice?
precuationary action
treatment actions
name some precautionary actions to combatt sea lice.
- cleaner fish
- selective breeding
- fallowing
- vaccines
- coordinated deployment of fish
name some treatment actions to combatt sea lice.
4
- )medical:
- 1 oral or 1.2. bath
2) mechanical
what is “cleaner fish” action?
what is positive, what is negative?
increasing or decresing use?
using fishes that feed on the sea lice
–> increasing use
positive: no chemicals, natural
negative: fear of transmitting disease, need cleaner nets
what speciesa res used as “cleaner fishes”?
lumpfish, wrasse species
on what depends “selective breeding” action?
what isthe goal?
how high were the susceptibility difference betw. salmon families?
depends on genetic variation in susceptibility to sea lice infection and the heritability of this.
–> breeding for lice resistence
70%
name some oral treatment medicaments and the benefits and negatives of oral treatments.
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.
name some benefits and negatives of bath treatments.
give some example for bath treatment substances.
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
what is MFMU?
medical free methods without handing
hat is MFMH?
medical free methods with handling
name some MFMH. what
3
need to be done to the salmon lice after the MFMH?
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
name some MFMU treatment.
3
cleaner fish
lasers
frehswater treatment in cage ()
how does the freswater MFMU treatemnt work?
affects iso osmotic balance of the lice (copepodids higher affected than preadult/adult stages)
name some preventive techological actions.
- lice skirts
- snokel cages
- submergable cages
- semienclosed cages
- electrical fences around the cage
what is the task force sea lice?
collaboration betw. most of the big salmon producing companies in trøndelag and NTNU
