Climate-fish relations in Norwegian waters

Abstract

Climate variability and change in the Arctic and Sub-Arctic regions have become increasingly important issues over the past few decades. The goal of the Arctic Climate Impact Assessment (ACIA) is to evaluate and synthesize knowledge on climate variability, climate change, and increased ultraviolet radiation and their consequences. Combined analysis of marine data records based on field observations and satellite Earth observation data records are being investigated in order to determine the relations between the variability in the marine physical and biological environment. The increased availability of satellite Earth observation data during the last 30 years have improved the role of use of these type of observations in the assessment of longer term variation in marine ecosystems. This report is mainly based on results from the FJOMP project (Fishery, Earth observation, Modeling and Prediction). The goal of the FJOMP project is to elaborate the use of satellite based information about the marine environment in the studies of the variability in the fish recmitment and stock assessment. The response of climate variation on the fish population is not well understood. In many stocks knowledge of the relationship between larvae and recruits and between recmits and spawning stock biomass is poor. Identifying which climate variables that have an impact on the fish at its different life stages may improve the knowledge of these relationships. Under the project FJOMP, a database, with the same name, with fishery and climate (mostly satellite based) time series was established. At this stage more than 40 climate and more than 30 fishery time series are included in the database. This database serves as a platform for a statistically approach in search for climate variables of importance for the fish populations. The effect of climate variation on fish recmitment and stock status has been investigated. In this study we have focused mainly on the relations between the ocean physical climatology and the three species, North East Arctic cod, Norwegian spring spawning herring and Barents Sea capelin. Climate and fishery time series in the FJOMP database have been systematically correlated, also with time lag, in order to search for interesting relationships. Also, multiple regression models have been used to further improve some of the most interesting correlations found. It is not the intent of this report to give deeper discussions on mechanisms and processes that link the climate variability to the fish populations, but instead give a taste of what this kind of linkage can give of contribution to the understanding of climatically effects on fishery recruitment and fish population variation. The results show that the North Atlantic Oscillation index (NAO) index and the sea surface temperature (SST) in general are two important climate variables for fish recmitment (however, they are not independent as NAO have a large impact on SST). Especially the NAO index gives good relations to several recruitment parameters for North East Arctic cod, while SST is more important for Barents Sea capelin and Norwegian spring spawning herring. In addition sensible heat flux, ice cover and heat transport are other important climate variables, which are related to the variability of the various fish classes and recruitment. NORSK SAMMENDRAG: Relasjoner mellom klimaparametere og fiskeriparametere har blitt undersøkt ved hjelp av FJOMPdatabasen (fiskeri, jordobservasjon, modellering og prediksjon). FJOMP-databasen inneholder fysiske- og fiskeriparametere relatert i de nordiske hav og Barentshavet. Vesentlige deler av databasen er basert på havmiljøparametere avledet fra in-situ-målinger og satellitt-jordobservasjoner. Korrelasjoner mellom fisk og klima er systematisk undersøkt, og flere I interessante koblinger er funnet. De mest interessante er presentert i denne rapporten.