Diet of St. Lawrence Estuary Beluga (<i>Delphinapterus leucas</i>) in a changing ecosystem

Abstract

<jats:p>Ecosystems and community structure fluctuate over time as a result of natural and anthropogenic factors that may affect prey availability and population dynamics. Most of what we know about St. Lawrence Estuary (SLE) Beluga (Delphinapterus leucas) diet comes from stomach contents collected 80 years ago mainly from a hunting site that Beluga no longer use. How reflective these data are of Beluga diet at other sites and at the current time is unknown. In the context of the recent population decline, general information of prey species alone may help identify useful conservation actions for potentially important prey or habitats. Here, we examined the diet of SLE Beluga using digestive tracts collected from carcasses recovered over the past 30 years, in the context of historical diet data and recent changes in the St. Lawrence ecosystem. We showed they have a varied diet composed of fish and invertebrates generally &lt;30 cm in length, and that adult males and females differ in their summer diet in a way that is consistent with the sex segregation observed in this population. Our results also indicate that polychaete worms, squid, and cod are still among the most prevalent prey, and that species such as redfish (Sebastes spp.) might be important prey items. This study shows that Beluga diet has changed since the 1930s, and that prey from digestive tracts identified to species are valuable for making comparisons to the past, and for improving applications of molecular analyses, such as stable isotopes and fatty acids.</jats:p>

Individual and population dietary specialization decline in fin whales during a period of ecosystem shift

“…Similarly, little information exists about the abundance of sandlance in the EGSL where it is suspected to be abundant 29 . This species may be an important prey for a number of marine mammal species in the St. Lawrence Estuary such as the beluga ( Delphinapterus leucas ) 30 and possibly also for fin whales as previously suggested for the Gulf of St. Lawrence 16 . In the latter study, also based on stable isotope analysis, sandlance occupied a functional group with northern krill that was estimated to contribute up to 50% of fin whale diets 16 .…”

Feces DNA analyses track the rehabilitation of a free-ranging beluga whale

“…Studies of diet composition from wild/dead beluga have typically relied on morphological stomach contents gathered from dead animals, stable isotopes, and fatty acid analyses 32 , 33 . The beluga whale is described as an opportunistic predator, targeting most commonly Atlantic cod as well as other fish and invertebrates, predominately shrimps, cephalopods, echiurids and amphipods 34 , 35 .…”

Back Into the Wild: Feces DNA Analyses Track the Return of a Beluga Whale Back to Its Natural Environment

“…Studies of diet composition from wild/dead beluga have typically relied on morphological, stable isotope, and fatty acid analyses 8,9 . These have shown that the beluga whale is an opportunistic predator, targeting both sh and invertebrates less than 30 cm in length.…”

“…These have shown that the beluga whale is an opportunistic predator, targeting both sh and invertebrates less than 30 cm in length. Changes in diet composition occur frequently by region, depth, and season 8,9 . Results here, from the concomitant use of COI and ribosomal 18S in metabarcoding analyses build upon this, and suggest a broader and more diverse range of prey are consumed, including many small or soft-bodied species 10 .…”