7210

• UCREFRP Catalog Number: 7210
• Author: McMahon, T. E. and J. W. Terrell.
• Title: Habitat Suitability Index Models
• USFW Year: 1982.
• USFW - Doc Type: Channel Catfish.
• Copyright Material: NO

Soule 1964; Andrews et al. 1972) and in areas with short agricultural growing
seasons (Starostka-and Nelson 1974). Upper incipient lethal levels for fry
are about 35-38° C, depending on acclimation temperature (Moss-and Scott-1961; .
Allen and Strawn 1968). Optimum salinities for fry range from 0-5 ppt;
salinities ? 10 ppt are marginal as"growth is greatly reduced'(A1len and
Avault 1970). _
Fry habitat suitability~in reservoirs is`~related .to f1us.hi-ng rage ~of
reservoirs in midsummer. Walburg (1971) found abundanc$ and survival of fry
greatly decreased at flushing rates < 6 days in July and August.
Channel catfish fry have strong shelter-seeking tendencies (Brown.. et al:"`
1970),-and cover availability will 6e important`in- determining habitat ,suit-~
ability: Newly hatched fry remain in the`nest.`for~7-8 days~(Marzolf 1957) and
then disperse to shallow water-areas with cover"(Cross and Collins `1975)`. Fry
are commonly found aggregated near cover in protected ,° slow-flowing (velocity
< 15 cm/sec) areas of rocky riffles; debris-covered gravel; or sand bars. in
clear streams .(Davis 1959; Cross``and Col 1 i n s ''i975) , and" i n very' sha'] 1 ow
..
(< 0.5 m) mud or sand substrate'edges,of.`flowing channels",along turbi,d.,rivers
and bayous~~(Bryan et~~al.~1975): "~~Dense ~aquati~c vegetation~~~genera7]y~does not
provide„optimum cover.-because predation 'on fry by centrarchids"is_high3under
these- conditions, especially in clear-water (Marzolf 1957 ;`Cross and Col ins
1975). Fry overwinter under boulders in riffles (Miller 1966) or move'' to
cover,in.deeper water (Cross and Cohi,ns 1975). - .- ..:
Juvenile. Optimal habitat for juveniles is assumed to be similar~to that
for fry. The temperature range most suitable for juvenile growth is reported
to be 28-30° C (Andrews et a1. 1972; Andrews and Stickney_1972): Upper lethal
temperatures are assumed to be similar to those for fry:- ~"
HABITAT SUITABILITY INDEX (HSI) MODELS
Model Applicability
Geographic area. The model is applicable throughout the 48 conterminous
States. The standard of comparison for each individual variable suitability
index is the optimum value of the variable that occurs anywhere within the 48
conterminous States. Therefore, the model will never provide. an HSI of 1.0
when applied to water bodies in the Northern States where temperature related
variables do not reach the optimum values for channel catfish found in the
Southern States.
Season. The model provides a rating for a water, body based on its ability
to support a self-sustaining population of channel catfish through all seasons
of the year.
Cover types. The model i5 applicable in riverine, lacustrine, palustrine,
and estuarine habitats, as described by Cowardin et al. (1979).
Minimum habitat area. Minimum habitat area is defined as the minimum
area of contiguous suitable habitat that is required ,for a species to succes-
fully live and reproduce. No attempt has; been made to establish a minimum

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