Four decades of reef observations illuminate deep‐water grouper hotspots

Abstract

Fish often aggregate to spawn, feed, rest, or avoid predation. Direct observations of very high counts of large‐bodied grouper on deep shipwrecks, however, do not fit into typical descriptions of spawning‐, resource‐, or predation‐driven aggregations. To investigate whether these observations are rare or part of an underlying pattern, we synthesized four decades (1979–2019) of direct observations of groupers on deep‐water (50–300 m) habitats along the southeastern United States (Cape Hatteras, NC to Cape Canaveral, FL). The direct observations, which included 439 remotely operated vehicle transects, 235 human‐occupied vehicle transects, and 881 hook‐and‐line drops, revealed six hotspots of deep‐water groupers on three shipwrecks, two artificial reefs, and one boulder field. Grouper counts at these hotspots (0.10–5.40 grouper per linear m surveyed) exceeded counts of grouper outside of hotspots (

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