7727

• UCREFRP Catalog Number: 7727
• Author: Stuber, R. J., G. Gebhart and O. E. Maughan.
• Title: Habitat Suitability Index Models
• USFW Year: 1982.
• USFW - Doc Type: Green Sunfish.
• Copyright Material: NO

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Specific Habitat Requirements

Green sunfish typically inhabit pool areas of streams (Brown 1960;
Minckley 1963; Harlan and Speaker 1969), and optimal riverfne habitat consists
of at least 50% pool area. Species abundance is positively correlated with
percent vegetative cover (Moyle and Nichols 1973). Forshage and Carter (1974)
attributed reductions in game fish populations, which included green sunfish,
to reductions in sheltered areas consisting of logs, brush, and gravel. More
than 80?~ cover is assumed to be suboptimal, because it provides too much
protect i on for green sunfi sh prey. Green sunfi sh have been found at a wi de
range of gradientS, varying from 0.2 to 5.7 m/km (Cross 1954; Funk 1975a);
however, they are most abundant at lower ($ 2 m/km) gradients (Trautman 1957;
Funk 1975b). They prefer small to medium-sized (< 30 m width) streams
(Trautman 1957; Cross 1967; Moyle and Nichols 1973).

Green sunfish also thrive in lacustrine environments. Optimal habitat
consists of fertile lakes, ponds, and reservoirs with extensive (~20% of
lacustrine surface area) littoral areas (Scott and Crossman 1973). Optimal
cover within littoral areas is similar to riverine criteria. Jenkins (1976)
reported a significant positive correlation between TDS levels of 100 to
350 ppm and sportfish (which included sunfishes) standing crop.

Water quality criteria for green sunfish in both riverine and lacustrine
environments are outlined as follows. High species abundance is positively
correlated with moderate (25-100 JTU) turbidities (Trautman 1957; Cross 1967; 41
Moyle and Nichols 1973), although the species occurs in both clear and turbid
water (Jenkins and Finnell 1957). Dissolved oxygen (D.O.) requirements are
presumably similar to those of the bluegill sunfish. Thus, optimal D.O.
levels are> 5 mg/l (Petit 1973), and lethal levels are $ 1.5 mg/l (Moore
1942). Using Stroud's (1967) crlteria for freshwater fish, optimal pH range
is from 6.5 to 8.5. Assuming green sunfish exhibit similar responses to pH
levels as do bluegill, mortality may occur at pH levels $ 4.0 or ~ 10.35
(Trama 1954; Calabrese 1969; Ultsch 1978). If green sunfish have salinity
tolerances similar to those of bluegill, optimal salinities are < 3.6 ppt
(Tebo and McCoy 1964), and green sunfish will not tolerate salinities> 5.6 ppt
(Kilby 1955).

Adul t. The temperature preference for adul t green sunfi sh is 28.20 C
and, when possible, they avoid temperatures above 310 C or below 260 C
(Beitinger et al. 1975). Green sunfish have been found in the field at temp-
eratures as high as 360 C (Sigler and Miller 1963; Proffitt and Benda 1971).
Growth and food conversion efficiency increased as temperature increased from
13.2 to 280 C (Jude 1973).

Adults are found in low current velocity areas (Gerking 1945; Brown 1960;
Minckley 1963; Summerfelt 1967; Harlan and Speaker 1969; Moyle and Nichols
1973). Based on catch data, preferred current velocities are $ 10 cm/sec, but
adults will tolerate velocities up to 25 cm/sec (Kallemyn and Novotny 1977;
Hardin and Bovee 1978).

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