1 1 Present Address: California Department of Fish and Game, 1416 Ninth Street, 12th Floor, Sacramento, California 95814, USA 1 Corresponding Author: epert@dfg.ca.gov Lotic-dwelling Age-0 Smallmouth Bass As Both Resource Specialists and Generalists: Reconciling Disparate Literature Reports EDMUND J. PERT 1 , DONALD J. ORTH, AND MATTHEW J. SABO Virginia Polytechnic Institute and State University, Department of Fisheries and Wildlife Sciences, Blacksburg, Virginia, 24061-0321, USA Abstract.—Numerous published reports indicate that age-0 smallmouth bass are habitat and food specialists, while fewer report that age-0 smallmouth bass are generalists. We find it striking that within individual studies, age-0 smallmouth bass are frequently reported as specialists, yet among studies they often specialize on different types of habitat and prey. A review of the literature and our personal findings and observations indicate that age-0 smallmouth bass may have an exceptional ability to take advantage of food and habitat resources that may be under-utilized within a given system. We hypothesize that age-0 smallmouth bass have evolved as flexible resource users to increase their survival in naturally variable environments by minimizing interactions with other fishes. This flexibility would provide an important mechanism for the coexistence of smallmouth bass with other fishes, including other centrarchids, with which age-0 bass are potential competitors. We believe that developing hypotheses from existing literature about age-0 smallmouth bass will improve the understanding of smallmouth bass evolution and ecology and result in more effective management. Introduction Smallmouth bass Micropterus dolomieu have been extensively studied because they are important sportfish and an integral component of many fish communities in North America. The large body of available scientific literature allows for a review to gain insight into large-scale ecological patterns re- lated to smallmouth bass. Based upon these pat- terns, hypotheses can be generated that can aid in management and direct future research. In this paper the literature reports on patterns of habitat use are synthesized with the diet of lotic-dwelling age-0 smallmouth bass. Such a synthesis is worth- while because of the wide-ranging findings of habi- tat use and diet in different populations of age-0 smallmouth bass. These disparate reports can be reconciled by considering all of these findings from an species-level evolutionary perspective. Habitat Use Age-0 smallmouth bass use a variety of lotic habi- tat types. They have been reported to use slow shal- low habitat (Bain et al. 1988; Livingstone and Rabeni 1991; Aadland 1993; Galbreath 1995), run habitat (Leonard and Orth 1988), edge habitat (Simonson and Swenson 1990; Lobb and Orth 1991), fast shallow habitat (Sabo and Orth 1994), and shallow and midwater depth habitat (Walters and Wilson 1996). In addition, they use a variety of cover types, including aquatic vegetation (Clark and Mancini 1980; Livingstone and Rabeni 1991; Walters and Wilson 1996), snags (Livingstone and Rabeni 1991; Lobb and Orth), and rocky substrate (George and Hadley 1979; Sabo and Orth 1994). They have been described as both habitat general- ists (Lobb and Orth 1991; Walters and Wilson 1996; Galbreath 1995) and habitat specialists (Bain et al. 1988; Aadland 1993). Even though some of the vari- ability in habitat use may be due to variation in habitat availability and differing definitions of habi- tat types, it seems clear that based on these ac- counts, age-0 smallmouth bass have the ability to use a wide variety of habitats and cover types. Diet The literature on diets of age-0 smallmouth bass indicates a fairly consistent foraging pattern over the first year of life; they consume a variety of in- vertebrates until they are large enough to consume fish, at which time some individuals begin forag- ing on fish as well as large invertebrates such as