Evaluating Prey Availability for the Rice's Whale (Balaenoptera ricei) Based on Environmental DNA

Area of Science:

• Marine biology
• Conservation genetics
• Environmental DNA (eDNA) analysis

Background:

• Foraging ecology of endangered marine mammals is crucial for conservation but difficult to study due to their elusive nature.
• Understanding Rice's whale (Balaenoptera ricei) diet is vital for its critically endangered status.

Purpose of the Study:

• To characterize potential prey communities for Rice's whale using eDNA metabarcoding.
• To compare eDNA metabarcoding with traditional trawl surveys for prey detection.
• To update the understanding of prey availability in Rice's whale core habitat.

Main Methods:

• Collected 21 water samples from Rice's whale feeding areas in the northeastern Gulf of America.
• Utilized eDNA metabarcoding with two 12S rRNA markers to identify fish species.
• Expanded reference databases by sequencing 12S rRNA from 15 regional fish species.

Main Results:

• Detected 99 fish species, exceeding diversity found in concurrent trawl surveys.
• Identified 74 fish species unique to eDNA, while 16 trawl-caught species were missed by eDNA.
• eDNA showed higher detection rates for key prey taxa, updating the list of potential prey.

Conclusions:

• eDNA metabarcoding is a valuable complementary tool for monitoring Rice's whale prey.
• Key prey species may be more abundant in Rice's whale habitat than previously thought.
• Continued development of marine metabarcoding reference databases is essential for ecological insights.