Paired male and female Tanner crabs, Chionoecetes bairdi, in a premating embrace were collected from shallow-(< 13 m) and deepwater (> 150 m) benthic environments by scuba and submersible, respectively. Pubescent females were restricted to shallow water; males grasping them were significantly smaller than those grasping oldshell multiparous females with eyed embryos in a large, deepwater mating aggregation. Males appeared to select for large sizes among pubescent females, but not among multiparous females, which were limited in size range. Grasping males were 82.6–166.2 mm carapace width (CW) [Formula: see text] and represented at least three different width frequency modes; all were larger than their female partners. Paired females represented two modes with mean CW ≈ 77 mm for pubescent and 99 mm for multiparous individuals. Only one to three of 176 male graspers were small-clawed (morphometrically immature), a statistically nonsignificant proportion; several others had partially regenerated claws but were otherwise morphometrically mature, as evidenced by the second right merus. These data support the hypothesis that the attainment of morphometric maturity, evidenced by a relatively large chela to body size ratio, is a prerequisite for functional maturity, the ability to mate competitively in wild populations.
Size, growth, and density have been studied for North American Pacific coast sea urchins Strongylocentrotus purpuratus, S. droebachiensis, S. polyacanthus, Mesocentrotus (Strongylocentrotus) franciscanus, Lytechinus pictus, Centrostephanus coronatus, and Arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956 to present. Numerous peer-reviewed publications have used some of these data but some data have appeared only in graduate theses or the gray literature. There also are data that have never appeared outside original data sheets. Motivation for studies has included fisheries management and environmental monitoring of sewer and power plant outfalls as well as changes associated with disease epidemics. Studies also have focused on kelp restoration, community effects of sea otters, basic sea urchin biology, and monitoring. The data sets presented here are a historical record of size, density, and growth for a common group of marine invertebrates in intertidal and nearshore environments that can be used to test hypotheses concerning future changes associated with fisheries practices, shifts of predator distributions, climate and ecosystem changes, and ocean acidification along the Pacific Coast of North America and islands of the north Pacific. No copyright restrictions apply. Please credit this paper when using the data.
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