Cecilia Kvaavik, a PhD student at Matís and MRI will present her work:
Assessment of diet and feeding preferences of mackerel (Scromber scrombrus) and their interaction with herring (Clupea harengus) in Icelandic waters
Warming of the world’s oceans has caused many pelagic marine species to shift their distribution - especially in a pole wards direction. Extensive numbers of pelagic fish enter the Icelandic waters during summer to feed. In 2012-2014, it was estimated that ~1.5 million tonnes mackerel (Scombrus Scomber) and ~ 3 million tonnes herring (Clupea harengus) are within the Icelandic EEZ each year during their summer feeding migration, indicating that these stocks can exert significant top-down pressures on the food web. Both mackerel and herring are mainly filter feeders, though mackerel tend to be more opportunistic and feed on a variety of larger zooplankton and small fish. Research into the diets of these two species suggests that the main zooplankton prey species in Icelandic waters are copepods (primarily Calanus finmarchicus), euphausiids, pteropods, amphipods and appendicularia. Mackerel also include fish prey such as larval sandeel (Ammodytes spp.), herring and capelin (Mallotus villosus). It is important to know when, where, and what fish eat as well as the differences between the diets of these two key pelagic species and the trophic links between them to provide an insights into competition between “invaders” and natives for limited food resources as well as intraspecific competition, which is central to ecosystem based fishery management and conservation.