Food web interactions in the southwestern Barents Sea: black-legged kittiwakes Rissa tridactyla respond negatively to an increase in herring Clupea harengus

Since 1980 the stock of Norwegian spring-spawning herring Clupea harengus has increased 10-fold to > 5 × 10 6 t.This increase has probably played a vital role in repeated collapses in the capelin Mallotus villosus stock in the Barents Sea since the mid-1980s.After several decades of increase during a period of high capelin abundance in the Barents Sea, the population of blacklegged kittiwakes Rissa tridactyla breeding in northern Norway started to decline in the early 1980s, reaching rates of -8% yr -1 since 1995.Earlier studies in the southwestern Barents Sea suggested that the black-legged kittiwakes in the region were dependent on capelin as prey for successful breeding.This study further documents a positive relationship between diet composition and fish abundance, and the negative effect that a switch to feeding on herring in the absence of capelin has had on chick provisioning and possibly fledging success.