Spawning Aggregation of Beardfish, Polymixia lowei, in a Deep-water Sinkhole off the Florida Keys
A large spawning aggregation of Polymixia lowei, Beardfish, was documented via video and specimen collection in a deep-water (413 m) sinkhole off Key West, Florida on 5 June 2007. The use of the human-occupied submersible, Johnson-Sea-Link II, allowed for in situ observations, video documentation, and specimen collection. The maximum density (117 fish m−2), average abundance (56 fish m−2), and average standard length (152.1 mm) were estimated from video transects. Ovarian histology of the fish collected indicated recent spawning activity. Observations of a deep scattering layer above the sinkhole by echo sounder suggested that P. lowei were in the water column during the pre-dawn hours. This represents the first report of aggregating behavior for reproduction in P. lowei.Abstract
(A) Echosounder transect heading 275 dg., Sinkhole B, R/V Seward Johnson, depth scale lines = 30.4 m; (B) wide angle view of Polymixia lowei, frame grab from digital video, JSL II Dive #3589 (field of view width 2 m); (C) close up of dense aggregation of P. lowei, JSL II Dive #3589 (field of view width 0.9 m).
Ovarian histological preparation, Polymixia lowei, HBOM 107:09501. (A) Scale bar = 100 µm. (B) Scale bar = 10 µm. P, primary growth oocyte; POF, post-ovulatory follicle; CA, cortical alveolar oocyte.
Contributor Notes
Associate Editor: J. W. Snodgrass.