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Smallmouth bass 2000 rM • =Adult o =Juveniles 2001 1000- 500 1001 400 m 300. : . 0 601 rtt E o 200 co 100 0 000 20 01 . 0 0 0 400 600 1200 WU.A (m2) rn W1 N N E 2 M WUA (m2) Freckled madto.m 100e- • 80-- 60- 600- 40- 20- 0 • • 80 160 240 200 400 WUA (m2) V4UA (m2) FIG. 4. I'lots of standing stock of Glover Creck fishes and WUA (data Iroiii tables 5 and 6 of Orth and Maughan 1982). *:The presence of a significant positive correla((ton between the WUA and bionlass of Fishes (grams) is interprel!ed as confirma- tion that physical habitat limits the fish stock and the o ulation is at caM-ing capacity (Orth and Mau han 1982): he absence o statistical come anon is Intetprete that factors other than those measured limit the standing stock. a have plotted in Fig. 3 and 4 the seasonal fish biomass and WUA data for small- mouth bass, orangebelly darter (Etlreostonta radiosunt), freckled madtom (Noturus trocturnus), and central stoneroller given by Orth and Mauphan 0992) in their tables 5 and 6 to examine tile. assumption of linear positive relationship (grams vs. W11iV. Both treasures of biomass (grams and grants per WUA) are highly variable and a positive relationship is not apparent (Fig. 3 and a). In fact, the trend is often negative, particularly that of the grams per Wl)A vs. WUA relationship. In audition, the lines do not aooear to pass throueh the orit?i 1 Some IHN1 studies (Gore and Judy 1981; Orth and Maugban 1983) on,benthic organisms have tested the above assumed linear relationship by transforming the original biomass data to in f X + 1). These transfoniied data were then repressed on joint preference values derived from the ritzy hiomass data (Core anti Judy 1981; Orth and pIaughan 1983). Despite this c•alibratiutt operation, i.e. regression of the original dependent (derived) variable, preference factor, against the original independent variable (biomass), consistent strong predictive relationships were absent. This result is surprising, since the prelerence of suitability values have little meaning except in tcnn. i f hiufua or densities. The slope of the relationship between fish bionlass (kilo- grams) and WUA is kilograms per WUA and therefin-e should be a constant, particul:0% for a population at cliff) illy, capacity in a given stream. Thi, conclusion is merely an extension of the iFiM original assump(ion of a slope of I flluvice 1978) fur tale relationship betwcen hiomass (kilograms) amt WILIA t(u list] populations at carrying capacity. That is a unit chant/ e i VI' A rNCnltc in a unit rhnnnr in hiontazc- In other \tords Ii units ut WUA sho yniahilityoh5 rued in Fie. 3 should not occur. The ralrulations of NVUA imnlicitly consider each habitat unit as biologically equivalent (Boyee 1992). Itowever. there is no reason to believe thnt hahitnr units a elifl 1t] FBI IA1;? S? Cali I. FishAquat. Sc•i., Vol. 42, 1995 R24 200 400