Survival, Growth, and Prey of Esocidae in
Experimental Systems
A. STEPHEN WEITHMAN AND RICHARD O. ANDERSON
Prey Vulnerability
Vulnerability to esocid predation was
highest for gizzard shad, goldfish, and
golden shiners, intermediate for bluegills
and largemouth bass, and lowest for channel
catfish. Variability in the results of six
prey-vulnerability trials was low; values
were averaged and presented as a percentage
of numbers eaten per number offered
for each prey species (Fig. 4). The largest
variation was in goldfish vulnerability; hybrids
consumed 35%, as compared with 58%
by northern pike and 62% by muskellunge
(Fig. 4). Electivity values (Ivlev 1961) were
positive for gizzard shad, goldfish, golden
shiners, and bluegills, near zero for
largemouth bass, and were negative for
channel catfish (Table 3).
Esocids in general, and
the hybrid in particular, should be able to
consume adult gizzard shad at a younger age
than other game fish.
Many studies have been conducted on the
food preference of esocids, especially
northern pike. Some investigators have reported
that esocids are piscivorous and feed
indiscriminately (Frost 1954; Crossman
1962); others have found that when given a
choice, northern pike prefer non-game over
game species (Beyerie and Williams 1%8;
Hunt 1965). We concur with the second
group--that when given a choice of prey
species, esocids feed selectively. In Pomme
de Terre Reservoir, muskellunge consumed
gizzard shad, carp (Cyprinus carpio), and
bluegills in that order (Vasey 1968). In confinement,
northern pike preferred gizzard
shad and carp over largemouth bass and
bluegills (Mauck and Coble 1971).