HypOnFjordFish - Hypoxia effects On Fjord Fish - Pilot Study
1 Purpose
The purpose is to evaluate to what extent larvae of mesopelagic fish are metabolically affected by hypoxia conditions observed in Norwegian fjords.
2 Distress
Larvae will be subject to closed respirometry at hypoxic conditions and their respiration contrasted against respiration at normoxic conditions. Measurements of free-swimming fish larvae undertaken at normoxic conditions is considered to incur up to mild stress, while the treatment groups at hypoxic conditions are expected to experience moderate distress.
3 Expected benefit
The results seek to clarify if population changes in mesopelagic fish abundance in Norwegian fjords are affected by climate induced hypoxic conditions. This is high relevance as recent studies have indicated an potential climate-induced increasing occurrence of hypoxic conditions in deep water layers where mesopelagic fish reside. It is yet to be documented whether this amounts to a significant environmental stress of the early stages of mesopelagic fish larvae
4 Number of animals, and what kind
We will if we succeed with larvae rearing use the species northern lantern fish (Benthosema glaciale) and Müllers pearlside (Maurolicus muelleri). Fertilized eggs will be sampled from the field and hatched in the laboratory. For the respiration measurements we plan to use 200 individuals of each species, at two temperatures. Successful rearing of mesopelagic has to our knowledge never been accomplished before, and as such the there is a reasonably high risk that we may not succeed in our production efforts for at least one of the species under investigation.
5 How to adhere to 3R (Reduction, Refinement, and Replacement)
Reduction:
We will use as few larvae as possible, while still having reasonable statistical power to detect potential relevant biological differences between control and exposed groups. As mesopelagic fish are highly abundant in our waters, our collection of filed material, if successful, will only represent a miniscule proportion of available offspring.
Refinement:
We will use our extensive previous experience in rearing marine fish larvae, while acknowledging that there are no accounts or information available specifically providing advice on rearing of mesopelagic fish larvae. We will use common animal welfare protocols relating to scoring and removal of larvae based on behaviour and appearance, sampling procedures, and termination of experiment. We will stop measurements before unnaturally high mortality exceeding field estimates occur.
Replacement:
As there are no previous data on temperature dependent development rates and metabolic rates for the mesopelagic fish larvae, no model replacements are readily available. Given their peculiar life histories, using literature values from other fish species will be highly speculative, and possibly significantly different. We thus conclude that there is no suitable replacement of experiments with the actual species in this case.
The proposed protocols are the same for the two species as we have no apriori information to suggest any different treatment in regards to the experimental setup.
The purpose is to evaluate to what extent larvae of mesopelagic fish are metabolically affected by hypoxia conditions observed in Norwegian fjords.
2 Distress
Larvae will be subject to closed respirometry at hypoxic conditions and their respiration contrasted against respiration at normoxic conditions. Measurements of free-swimming fish larvae undertaken at normoxic conditions is considered to incur up to mild stress, while the treatment groups at hypoxic conditions are expected to experience moderate distress.
3 Expected benefit
The results seek to clarify if population changes in mesopelagic fish abundance in Norwegian fjords are affected by climate induced hypoxic conditions. This is high relevance as recent studies have indicated an potential climate-induced increasing occurrence of hypoxic conditions in deep water layers where mesopelagic fish reside. It is yet to be documented whether this amounts to a significant environmental stress of the early stages of mesopelagic fish larvae
4 Number of animals, and what kind
We will if we succeed with larvae rearing use the species northern lantern fish (Benthosema glaciale) and Müllers pearlside (Maurolicus muelleri). Fertilized eggs will be sampled from the field and hatched in the laboratory. For the respiration measurements we plan to use 200 individuals of each species, at two temperatures. Successful rearing of mesopelagic has to our knowledge never been accomplished before, and as such the there is a reasonably high risk that we may not succeed in our production efforts for at least one of the species under investigation.
5 How to adhere to 3R (Reduction, Refinement, and Replacement)
Reduction:
We will use as few larvae as possible, while still having reasonable statistical power to detect potential relevant biological differences between control and exposed groups. As mesopelagic fish are highly abundant in our waters, our collection of filed material, if successful, will only represent a miniscule proportion of available offspring.
Refinement:
We will use our extensive previous experience in rearing marine fish larvae, while acknowledging that there are no accounts or information available specifically providing advice on rearing of mesopelagic fish larvae. We will use common animal welfare protocols relating to scoring and removal of larvae based on behaviour and appearance, sampling procedures, and termination of experiment. We will stop measurements before unnaturally high mortality exceeding field estimates occur.
Replacement:
As there are no previous data on temperature dependent development rates and metabolic rates for the mesopelagic fish larvae, no model replacements are readily available. Given their peculiar life histories, using literature values from other fish species will be highly speculative, and possibly significantly different. We thus conclude that there is no suitable replacement of experiments with the actual species in this case.
The proposed protocols are the same for the two species as we have no apriori information to suggest any different treatment in regards to the experimental setup.
Etterevaluering
Mattilsynet er etter regelverket forpliktet til å etterevaluere alle forsøk som er betydelig belastende for forsøksdyrene, og kan også etterevaluere forsøk med lavere belastningsgrad.
Begrunnelse for etterevalueringen
Målet med forsøket ble ikke oppnådd fordi det var vanskelig å få tak i tilstrekkelig mengder av levedyktige, befruktede egg i fra felt med den innsamlingsmetoden som ble benyttet.
Forskerne vurderte at en større innsats og et mer gunstig valg av tidspunkt og sted kunne gitt et bedre resultat. Dette lot seg ikke gjøre innenfor gitte totalrammer og tilgang til forskningsfartøy.
Innsamling av egg i fra mesopelagisk fisk i felt ble gjennomført, og ca. 100 egg ble overført til inkubatorer på land. Det ble observert klekking av et fåtall larver fra laksesildegg, men ingen overlevde utover et par dager og frem til forsøksstart og respirasjonsmålinger.
Selv om målet med forsøket ikke ble nådd, ble det erfart at det det er mulig å samle inn befruktede egg fra pelagisk fisk som klekker i laboratoriet. Dette gir grunnlag for nye initiativ fremover. Forskerne trenger imidlertid mer erfaring med hold av nyklekte larver av disse artene.
Forskerne vurderte at en større innsats og et mer gunstig valg av tidspunkt og sted kunne gitt et bedre resultat. Dette lot seg ikke gjøre innenfor gitte totalrammer og tilgang til forskningsfartøy.
Innsamling av egg i fra mesopelagisk fisk i felt ble gjennomført, og ca. 100 egg ble overført til inkubatorer på land. Det ble observert klekking av et fåtall larver fra laksesildegg, men ingen overlevde utover et par dager og frem til forsøksstart og respirasjonsmålinger.
Selv om målet med forsøket ikke ble nådd, ble det erfart at det det er mulig å samle inn befruktede egg fra pelagisk fisk som klekker i laboratoriet. Dette gir grunnlag for nye initiativ fremover. Forskerne trenger imidlertid mer erfaring med hold av nyklekte larver av disse artene.