During the PINRO atumn bottom trawl survey in 2007-2008, samples were collected as a basis for estimation of pre-spawning stock of euphausiids (Figure 4.3.7 A, B). The study showed that the abundance of euphausiids crustaceans was higher than the long-term means from the sampling area, and the arctoboreal species Thysanoessa inermis was the most dominating species.
The average abundance of these small crustaceans was higher in 2008 compared to 2007 (Figure 4.3.8), and the density of euphausiids aggregations was noticeably lower in the central and western parts of the Barents Sea. On the contrary, the abundance of euphausiids exceeded long-term means by 3 times in the south and southeastern parts with a number of 1200 individuals per 1000 m3. The abundance of the warm-water species Meganyctiphanes norvegica has stayed relatively high in the central Barents Sea with a number of up to 110 individuals per 1000 m3, and 170 individuals per 1000 m3 in coastal areas. The abundance of this species has in the meanwhile decreased in the western and eastern areas (Figure 4.3.9).
It’s assumed that the decrease of meso- and macroplankton aggregations in the center and western parts of the Barents Sea is probably caused by higher fish predation – in particular from increasing stock of capelin.