Linking Ecological Conditions to Size-Distributions of Abyssal Scavengers Across the Eastern and Central Pacific Ocean

Abstract

Spanning across the Pacific Ocean is a community of abyssal scavengers, constantly foraging for carcasses that sink to the deep-ocean floor. Baited-camera deployments enable in situ observations of this poorly understood community, but few studies have been able to evaluate scavenger sizes. Stereo-video camera footage from across the Clarion-Clipperton Zone (CCZ) and Hawaiʻi was analyzed to obtain length measurements of the widespread macrourid fishes, Coryphaenoides armatus/yaquinae, and compare size-frequency distributions across the Eastern and Central Pacific and to variation in environmental parameters. There was a distinct difference in fish size between the east and west CCZ, with larger individuals in regions near bathymetric highs and with higher surface productivity, corresponding to increased food availability. Observations off the coast of Hawaiʻi showed the mean size of rattails was two-fold larger in the winter compared to summer, indicating a strong seasonal pattern in the scavenger community, potentially influenced by the carcasses of migratory species such as tuna. Across the entire study region, areas of higher productivity and bathymetric highs featured larger fish, while polymetallic nodule cover, slope, temperature, and particulate organic carbon (POC) flux were not significantly related to fish size. Determining the relationships between C. armatus/yaquinae size and ecological factors can inform management strategies involved in monitoring anthropogenic impacts and safeguarding the resiliency of deep-sea communities.