Figure 1.
Differences in neuromast number across groups.
(A) SN were clustered in one of six discrete ‘stitches’ or groupings, which we term for convenience in the present report S1–S6. Each of these stitches was treated as a region of interest for analysis of neuromast number. (B–E) Examples of DASPEI-labeled neuromasts from wild-origin juveniles (B–C) or Cook Creek hatchery fish (D–E). (B) Stitches S1–S2, showing how S2 intersects S1 near its midpoint, running anteroventrally toward the eye. Scale bar = 1 mm. (C) Low-magnification image of the left side of the head, showing the stitch around the naris (S3) and the stitch over the operculum (S4). The infraorbital canal (IC) is also labeled in this image. This canal was not clearly visible in all specimens so neuromast number was not quantified. Scale bar = 2 mm. (D) Stitch S3 (bordering a right-side naris) under higher magnification. Scale bar = 1 mm. (E) SN from stitch S5 (arrowheads), which sits atop the trunk canal (arrows). Trunk canal neuromasts are elongated in the rostrocaudal direction, while adjacent SN are oriented dorsoventrally. Scale bar = 1 mm. (F) Total neuromast number (summed across left and right sides) per fish (open circles) and per group (filled circles, mean±1 SEM, n = 10 fish per group). There were significant differences in neuromast number between groups (one-way ANOVA F1,2 = 9.45, p = 0.001). (G) SN number comparisons within each ROI using one-way ANOVA followed by Tukey's post-hoc analysis. Individual and group data are plotted across ROIs. Statistical tests are summarized are in Table 1.
Table 1.
Statistical comparison of SN number across groups.
Figure 2.
High variability in hair cell number within neuromasts.
(A–C) Confocal images (brightest-point projections) of neuromasts double-labeled with anti-acetylated tubulin (red) and phalloidin (green), showing the kinocilia and hair bundles/cuticular plates, respectively. The phalloidin label also delineates overall neuromast architecture. (A) Three neuromasts from stitch S2 of a wild-origin fish, showing neuromast morphology and spacing. (B) Single SN from stitch S3 of a Lake Quinault hatchery fish, demonstrating the rounded morphology sometimes observed. In contrast, elongated SN were more typically noted, illustrated here by the S5 neuromast from a Cook Creek fish (C). (D) Average hair cell number for 4 randomly selected individuals (open circles) from each group for which complete data (SN in all four dissected ROIs S1–S4; range 3–21 SN per ROI) were available, and group means (filled circles, mean ± 1 SEM) for each ROI. There were no significant cross-group differences in hair cell number (p>0.05).
Figure 3.
Sagittal otolith calcium carbonate composition.
Transmitted light images of a normal (aragonite) sagitta from a wild-origin juvenile (left) and a crystallized (vaterite) sagitta from a Cook Creek hatchery fish (right). Scale bars in each image = 1 mm. (B) Relative proportion of aragonite (black) and vaterite (gray) sagittae in fish from each population (wild n = 20 otoliths (10 fish×2 otoliths each), Cook Creek = 28 otoliths, Lake Quinault = 34 otoliths). Both groups of hatchery fish had a significantly higher proportion of crystallized otoliths than wild fish (Chi-square tests, p = 0.001).
Figure 4.
Brain weight differs between groups.
Normalized brain weight, expressed as the brain/body weight ratio, of 8 randomly selected individuals (open circles) from each group and means for each group (filled circles, mean ± 1 SEM). The inset shows a brain from a wild-origin juvenile with the olfactory bulbs removed. Scale bar = 2 mm.