The Pearl River Delta(PRD)region on the southeast coast of China has long been known as a highly productive fishing ground.Since the late 1980s,fishing pressure in the PRD has been intense,which warrants concerns of p...The Pearl River Delta(PRD)region on the southeast coast of China has long been known as a highly productive fishing ground.Since the late 1980s,fishing pressure in the PRD has been intense,which warrants concerns of potential fishery-related impacts on the food resources and foraging ecology of apex marine predators in this region,such as the Indo-Pacific humpback dolphin(Sousa chinensis).In this study,we examined 54 stomachs with food remains,collected from beached carcasses of humpback dolphins recovered during fifteen years between 2003 and 2017.The 6043 identified prey items represent 62 teleost taxa,primarily small estuarine fish,but also larger reef fish.The dolphins appear to be opportunistic foragers,hunting across the water-column,with preference for shoaling and meaty fishes(e.g.Collichthys lucidus IRI%=38.6%,Johnius belangerii IRI%=23.1%,Mugil cephalus IRI%=14.0%).Our findings suggest a dietary shift in recent years,from primarily demersal(as previously reported)to greater intake of neritic and pelagic fish.Dolphin foraging group size has decreased in recent years,which corresponds with declining size and numbers of prey items retrieved from dolphin stomachs.We suggest that these are indicators of declining food resources.Faced with a shortage of preferred prey,humpback dolphins may have broadened their dietary spectrum to maintain their daily energy intake,while their foraging group size decreased in response to the altered tradeoff between the costs and benefits of group foraging.展开更多
基金This study was funded by the National Natural Science Foundation of China(41576128)the Natural Science Foundation of Guangdong Province(2017A030308005)in China+3 种基金the Ocean Park Conservation Foundation Hong Kong(MM01.1920)Alashan Society of Entrepreneurs and Ecology(SEE)the General Research Fund of the Research Grants Council(RGC)of Hong Kong(HKU_17100015 to LK and CityU_160613 to TCW)Field-based observations were facilitated by ongoing photo-ID study supported primarily with LK’s Marine Ecology Enhancement Fund grants MEEF2017015,MEEF2017015A and MEEF2017015B.
文摘The Pearl River Delta(PRD)region on the southeast coast of China has long been known as a highly productive fishing ground.Since the late 1980s,fishing pressure in the PRD has been intense,which warrants concerns of potential fishery-related impacts on the food resources and foraging ecology of apex marine predators in this region,such as the Indo-Pacific humpback dolphin(Sousa chinensis).In this study,we examined 54 stomachs with food remains,collected from beached carcasses of humpback dolphins recovered during fifteen years between 2003 and 2017.The 6043 identified prey items represent 62 teleost taxa,primarily small estuarine fish,but also larger reef fish.The dolphins appear to be opportunistic foragers,hunting across the water-column,with preference for shoaling and meaty fishes(e.g.Collichthys lucidus IRI%=38.6%,Johnius belangerii IRI%=23.1%,Mugil cephalus IRI%=14.0%).Our findings suggest a dietary shift in recent years,from primarily demersal(as previously reported)to greater intake of neritic and pelagic fish.Dolphin foraging group size has decreased in recent years,which corresponds with declining size and numbers of prey items retrieved from dolphin stomachs.We suggest that these are indicators of declining food resources.Faced with a shortage of preferred prey,humpback dolphins may have broadened their dietary spectrum to maintain their daily energy intake,while their foraging group size decreased in response to the altered tradeoff between the costs and benefits of group foraging.
