8142

• UCREFRP Catalog Number: 8142
• Author: Horn, M. J.
• Title: Nutritional Limitation of Recruitment in the Razorback Sucker ‎(
• USFW Year: 1996.
• Copyright Material: NO

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44
(Campana and Neilson 1985). Analytical bias in this study is likely due to a combination
of both.

Somatic and otolith growth rates were not proportional as indicated by differences

in slopes and intercepts of regressions of log, sagittal diameter as a function of TL

(Tables 5-6, Figure 12), and for regression of sagittal diameter on age between feeding

groups (Tables 7-8, Figure 13). Comparing results of the regressions indicates otolith

growth to be conservative. Slope of the former was shallower and for the latter steeper

for Ad libitum larvae. The first results from somatic growth (as represented by TL)

ceasing or proceeding at a reduced rate in larvae receiving suboptimal rations or starving,

where the otolith continues to grow faster than expected if directly proportional to

somatic growth. For the second, the opposite results from otolith diameter increasing

faster in well-fed larvae relative to those subjected to treatments resulting in slower

growth. Differences in intercepts are artifacts of slope differences (Campana 1990) since

all larvae were hatched under the same pretreatment conditions. Thus, otoliths continue

to grow (and form increments) for a period of time even when larvae are starving.

This conservative nature has been detected in numerous other cases where otolith

growth remains relatively stable during short-term fluctuations in feeding (Moosegaard

1980; Reznick et al. 1989; Francis et al. 1993). Atlantic cod (Gadus morhua) continued

to deposit increments in the absence of food for up to 14 d after hatching (Campana and

Neilson 1985). Northern anchovy (Engraulis mordax) on the other hand, ceased otolith

growth almost immediately when food became unavailable (Methot and Kramer 1979),

presumably due to limited energy reserves. Razorback sucker larvae followed the cod