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Use of Walleye Relative Weights ( W r ) to Assess Prey Availability
Author(s) -
Porath Mark T.,
Peters Edward J.
Publication year - 1997
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1997)017<0628:uowrww>2.3.co;2
Subject(s) - predation , stizostedion , fish <actinopterygii> , biology , fishery , population , abundance (ecology) , predator , zoology , ecology , demography , sociology
We investigated the effects of prey availability on relative weights ( W r ; the ratio of fish weight to the weight of a standard fish of the same length) in populations of walleye Stizostedion vitreum from two reservoirs, Lake Ogallala and Lake McConaughy, in western Nebraska. Partitioned by season of capture and 50‐mm length‐classes, walleye W r was compared with the abundance of prey fish by length‐class. Walleye W r changed seasonally and was heavily influenced by prey size availability. In Lake Ogallala, where smaller prey were abundant, there was no significant difference in W r across length‐classes by fall. In Lake McConaughy, where more than 90% of all prey fish were over 170 mm, there was a distinct trend by fall. Small walleyes (250–400 mm) exhibited the lowest W r (92.0 ± 0.84); and large walleyes (550–700 mm) had the highest W r (104.0 ± 1.57). Examining changes in walleye W r among length‐classes across seasons was more informative than using a mean population W r because it was sensitive to changes in prey availability for individual walleye length‐classes. We aggregated adjacent walleye length‐classes with similar W r values to form W r ‐groups to determine the length‐groups that were experiencing prey limitations. Identifying walleye length‐groups with common W r structure from standardized fall surveys may be a cost‐effective method of detecting prey fish deficiencies in reservoirs.