Bl. Johnson et Db. Noltie, DEMOGRAPHY, GROWTH, AND REPRODUCTIVE ALLOCATION IN STREAM-SPAWNING LONGNOSE GAR, Transactions of the American Fisheries Society, 126(3), 1997, pp. 438-466
The demography of breeding populations of the longnose gar Lepisosteus
osseus has heretofore remained unstudied. During the summer of 1992,
longnose gars were captured en route to spawning sites in Weaubleau Cr
eek, a tributary of Missouri's Harry S. Truman Reservoir. To character
ize the spawners, individual age, growth, and morphometric data were o
btained. The spawning population consisted of smaller, younger males a
nd somewhat fewer older, larger females. As expected, Weaubleau Creek
spawners exhibited heightened condition values relative to other longn
ose gar populations assessed outside the breeding season. Females disp
layed greater backcalculated total lengths at age and higher growth ra
tes than males, with these differences being manifested early in life.
Examination of individual yearly growth increments suggested that mos
t longnose gars in Weaubleau Creek were annual spawners. Females made
substantial investments of time and biomass in reproduction, as their
gonad weight-body weight relationships, fecundities, and spawning-asso
ciated weight and girth losses reflected. Males also invested heavily
in reproduction, but may have recouped some biomass through postspawni
ng instream foraging. Fish from nearby Truman Dam differed in their si
zes, condition, growth, relative gonad sizes, and relative branchioste
gal ray sizes, possibly reflecting the impact of earlier maturation as
sociated with abundant forage. A novel approach for assessing breeding
participation in fishes is also developed.