NINA-rapport 646: Laks i framtidens klima (pdf)

Innhold
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NINA Rapport 646
Sammendrag ............................................................................................................................ 3
Abstract .................................................................................................................................... 6
Innhold ...................................................................................................................................... 9
Forord ..................................................................................................................................... 11
1 Innledning .......................................................................................................................... 12
2 Klimascenarioer og scenarioer for vannføring og temperatur i ferskvann ................. 15
2.1 Utslippscenarioer og klimaprojeksjoner ....................................................................... 15
2.2 Vanntemperaturmodellering; metode .......................................................................... 19
2.2.1 Rice .................................................................................................................. 19
2.2.2 Øvre grenseverdi for vanntemperatur ............................................................... 20
2.2.3 Andre parametre som trengs til vanntemperatursimuleringene ........................ 23
2.3 Vanntemperaturmodellering; resultater og diskusjon .................................................. 25
2.3.1 Vanntemperatur ................................................................................................ 25
2.3.2 Isforhold ............................................................................................................ 32
2.3.3 Nøyaktighet ...................................................................................................... 32
3 Oppsummering av biologiske mekanismer .................................................................... 33
3.1 Innledning ................................................................................................................... 33
3.2 Temperaturtoleranse ................................................................................................... 34
3.2.1 Temperaturgrense ............................................................................................ 34
3.2.2 Variasjon mellom bestander ............................................................................. 35
3.3 Aktivitet og vandring .................................................................................................... 36
3.3.1 Parr ................................................................................................................... 36
3.3.2 Smoltvandring................................................................................................... 37
3.3.3 Gytevandringen ................................................................................................ 38
3.4 Gyting .......................................................................................................................... 40
3.4.1 Seleksjon påvirker gytetiden ............................................................................. 40
3.4.2 Variasjon i temperatur og gytetid ...................................................................... 41
3.5 Fosterutvikling, klekking og tilsynekomst .................................................................... 42
3.5.1 Utviklingstemperatur ......................................................................................... 42
3.5.2 Inkubasjonstid................................................................................................... 42
3.5.3 Fosterstørrelse ................................................................................................. 43
3.6 Tidlig dødelighet og bestandsrekruttering ................................................................... 43
3.6.1 Bestandsregulering ........................................................................................... 43
3.6.2 Vannføring ........................................................................................................ 43
3.6.3 Temperatur ....................................................................................................... 44
3.7 Vekst ........................................................................................................................... 44
3.7.1 Modeller ............................................................................................................ 44
3.7.2 Variasjon mellom bestander? ........................................................................... 45
3.8 Næringsopptak og veksteffektivitet ............................................................................. 46
3.9 Vekst i havet ............................................................................................................... 47
3.10 Livshistorievariabler .................................................................................................... 48
3.10.1 Smoltalder og -størrelse ................................................................................... 48
3.10.2 Vandring eller stasjonæritet .............................................................................. 48
3.10.3 Kjønnsmodning i postsmoltstadiet .................................................................... 49
3.10.4 Eggstørrelse og fekunditet ................................................................................ 49
3.11 Dødelighet og sjøoverlevelse ...................................................................................... 50
3.12 Hva vil framtidens klima bety for laksen? .................................................................... 50