When logbooks show the path: Analyzing the route and timing of capelin (Mallotus villosus) migration over a quarter century using catch data

The Timing of Global Change

“…In the Barents Sea, the shift is in the spawning locations and in Newfoundland the shift is in the feeding migrations, or main feeding locations are measured. In all three cases, the center of gravity is determined to find the location, see [46], following the methods in respectively, [45], [3] and [8]. The corresponding temperature and salinity shifts were both measured directly, and temperature was also measured remotely.…”

“…During that week, the migration has adjusted to the temperature of the spawning path but not yet sped up to optimize the time until spawning [18]. The figure shows the increase in the temperature at the old location, and we see a shift of 224.914 kilometers, see [45], between this new (blue) warmer temperature at the old location, and the new relatively cooler temperature (also blue) at the new location.…”

“…A careful examination of the catch data for the Icelandic stock [45] shows a significant shift toward the northwest of the averaged spawning migrations between the periods 1993-2002 and 2003-2018. Figure 3 shows the average temperature (left) and salinity (right) at the centroid of the second and third week fishery during the period of 1993-2002.…”

Detection and distribution of the North Atlantic capelin (Mallotus villosus) using environmental DNA—comparison with data from the main fishery management survey

“…In early January, capelin migrate from their feeding areas along the North Icelandic continental shelf edges for spawning in a clockwise direction toward the southern spawning locations (Carscadden et al, 2013). The location of spawning grounds has been consistent for decades despite changes in the location of the feeding area and changes in the timing of the spawning migration (Singh et al, 2020). However, in recent years, this variability in behavior expressed as a change in the location of the feeding habitat (Carscadden et al, 2013) and as a delay in the spawning migration (Singh et al, 2020) made it challenging to find capelin, both during the monitoring surveys along the east coast of Greenland and the fisheries occurring along the continental shelf of Iceland.…”

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Capelin Mallotus villosus is a small pelagic fish that plays an important economic and ecological role in the North Atlantic Ocean. Capelin fisheries have sustained communities in Nordic countries for several decades, with yields reaching up to 1.5 million tons during exceptionally good fishing seasons (Singh et al, 2020;Vilhjálmsson & Carscadden, 2002). In addition to its high economical value, capelin has also been shown to play a key role in the transportation of energy through the food web by feeding heavily on plankton and being the prey of larger organisms (Dolgov, 2002;Fall et al, 2018;Koen-Alonso et al, 2021).

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