Fjords are deep-water estuaries that support a wide range of marine habitats for pelagic fish. Yet, knowledge gaps in fish distribution and habitat use limit the implementation of efficient marine conservation strategies within fjords. Using British Columbia fjords as a case study, we demonstrated that eDNA metabarcoding combined with species traits can enhance the detection and monitoring of conservation priority species (CPS) within systematic conservation planning frameworks.
Samples were collected at four time-points: late January/February (winter), May (spring), August (summer), and November (fall) 2023 from the five British Columbia Fjords: Indian Arm (səl ̓ilwət in hən̓q̓əmin̓əm̓), Howe Sound (Átl'ḵa7tsem in Squamish), Toba Inlet (yɛkʷamɛn in Homalco), Bute Inlet, and Rivers Inlet (Wánuǧvaxsiwa in Oowekyala). Three to five stations were sampled within each fjord and discrete 2 L environmental DNA (eDNA) samples were collected using Niskin bottles at the surface, 10 m below the surface, 100 m below the surface, and 10 m above the bottom.
From the eDNA samples, the fish community was mapped using metabarcoding targeting a small region of the mitochondrial 12S rRNA gene using MiFish-U universal primer set. Independent sequencing libraries were prepared for each of the four seasonal datasets, and each was sequenced using Illumina MiSeq V3 chemistry at the Hakai Genome Lab on Quadra Island, BC.
Spatiotemporal eDNA patterns confirmed the presence of endangered eulachon (Thaleichthys pacificus) across three fjords and identified deep fjord habitats as conservation priorities for mesopelagic species, including sensitive elasmobranchs and diel vertical migrators such as northern lampfish (Stenobrachius leucopsarus). eDNA peaks for several CPS during winter and spring matched documented spawning windows, underscoring the importance of fjords as seasonal spawning habitat. This globally transferable approach can supplement local stewardship initiatives and long-term monitoring efforts, contributing to more effective marine conservation area design and management.
10.21966/n141-m959
