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  • Spatial and temporal trends of fifteen noncommercial fin-fish species in Iceland between 1985 and 2009
  • Meistara
  • A decline in the world fish stocks has been documented through scientific studies during the last 30
    years. In recent years, fisheries managers have acknowledged that single-species management
    approaches ignore the greater ecosystem context. In response, a shift from a single-species
    management to ecosystem-based management is occurring. True ecosystem-based management
    approaches must consider all aspects of the ecosystem including non-commercial species. This
    study uses the data collected from 25 years of scientific trawl surveys to analyze the trends in noncommercial
    fin-fish species, which serve as an ecosystem indicator. In this dataset between 508 and
    600 stations are surveyed each year (mean 558 stations per year) are sampled. At each station a 4.0
    nautical mile trawl is conducted and fish are counted and identified to species level. Species were
    selected based on the following criteria: they must not have any commercial value in Iceland
    (therefore never kept), they must have been captured in more than 1% of the surveys, and they
    must always be identified to species level. Fifteen species fit the above criteria and were selected for
    analysis. Three species (Leptagonus decagonus [Bloch & Schneider], Myoxocephalus scorpius
    [Linnaeus], and Cottunculus microps [Collett]) show a decreasing trend in population size while
    four species show increasing populations (Trisopterus esmarkii [Nilsson], Rhinonemus cimbrius
    [Linnaeus], Gaidropsarus argentatus [Reinhardt], and Chelidinichthys gurnardus [Linnaeus]).
    Additionally, the geographic center of eight species changed during time period studied. Three
    species shifted south (Triglops murrayi [Günther], Artediellus atlanticus [Jordan and Evermann],
    and C. microps), three species moved north (T. esmarkii, R. cimbrius, Rajella fyllae [Lütken]), three
    species migrated west (T. esmarkii, Boreogadus saida [Lepechin], and C. gurardus), and one species
    migrated east (C. microps). As would be expected with current warming water temperatures in
    Iceland, warm water species tended to increase in population (three out of four) and migrated
    north and west. None of the warm water species’ populations decreased. All species with
    decreasing populations were cold water species. Interestingly, two cold water species showed a
    positive trend in abundance and three cold water species had a southern component to their shift
    in distribution. These last results suggest that the role in changing ecosystem regimes and subtle
    temperature shifts can influence these species. The population and spatial trends of the species
    studied are of particular interest because the changes in these species are not confounded by the
    effects of harvest. The results can be used to better understand the effects of climate change on
    commercial fish species which occupy similar niches as the fish in the present study.

  • 22.6.2010

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