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<br />122
<br />Ft. Thomas on the mainstream of the Gila (Kirsch, 1889), and farther up-
<br />stream.il
<br />The comparable decline in abundance of squawfish in the Colorado
<br />River mainstream, below Lake Mead, as indicated in the quotation by
<br />Miller (1961 b) given above, has appeared to continue to essential ex-
<br />tinction. Minckley & Deacon (1968) heard of only two specimens from that
<br />region between 1962 and 1967 (one of which was seen and was from
<br />Lake Mead itself), and none has been reported subsequently.
<br />There is no published information on the life history of this fish in
<br />Arizona waters. Vanicek & Kramer (1969) have provided data, however,
<br />from the Green River in Dinosaur National Monument, and some informa-
<br />tion may be gleaned from a number of general publications (Simon, 1951;
<br />Beckman, 1963; Sigler & Miller, 1963; and others). Prior to dams, squaw-
<br />fish moved upstream in "runs" just before the spawning period. This, along
<br />with their great size, presumably result in the name "salmon." Other
<br />squawfishes, P. grandis (Ayres) of the Sacramento River basin (Taft &
<br />Murphy, 1950) and P. oregonensis (Richardson) (citations below), also
<br />seem to "run" into streams to spawn, at least in the past. Reproduction
<br />by Colorado River squawfish in the Green River appeared to occur in July
<br />and August, attuned to increasing water temperatures and receding water
<br />levels. In the southern part of its range, and perhaps in the Green River,
<br />Utah, before moderation of temperatures induced by damming, spawning
<br />must have occurred earlier in the year. Young, 32 mm long, were taken
<br />in mid-May in Arizona (Miller, in Sigler & Miller, 1963). Spawning by
<br />other species of Ptychocheilus occurs in early to late spring.
<br />Actual spawning sites or breeding behavior of P. luciushas yet to be
<br />observed. The northern squawfish (P. oregonensis) spawns in lakes or
<br />streams of the Columbia River basin, in shallow water over gravel or rubble
<br />(Jeppson & Platts, 1959), or in streams over larger rubble in riffles or at
<br />the lower ends of pools in tributaries (Keating, in Vanicek & Kramer, 1969).
<br />Spawning by P. grandis seems to occur at the lower ends of pools, just
<br />above riffles, or in riffles (Taft & Murphy, 1950). Spawning behavior of
<br />P. oregonensis in Merwin Reservoir, Washington, has recently been de-
<br />scribed in detail by Patten & Rodman (1969). Fish congregated in in-
<br />creasingly greater numbers from June, to a peak of reproductive activities
<br />in the first week of July. They were over a specific area of rocky bottom,
<br />deeper than three meters, but above the thermocline. Swarms of males
<br />moved slowly and irregularly about 30 cm above the bottom, with indi-
<br />viduals darting abruptly upward, then returning to the swarm. The
<br />11F. W. Chamberlain's 1904 field notes report as follows: "Several years ago fish
<br />were abundant (near Safford, Graham County, in the Gila River). Then pools of
<br />sufficient depth for men to swim in existed. Salmon reached a weight of 35 Ib.,
<br />humpback and other suckers were abundant. None of these has been taken in the
<br />last two years. It is believed that minerals and concentrate-wash from the mines
<br />and works at Morenci and Cliftcn have killed the fish."
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