I have read conflicting statements about when the Amazons were released into the San Marcos (via a broken aquarium that drained out a floor drain and into a storm outlet according to Clark Hubbs). Some accounts, albeit not "official" ones, say 1939, others give 1954, and some simply say mid-twentieth century. From the sources you cite below, the 1954 date seems likely. Clark would be able to say definitively. I checked his checklist in the Texas Journal of Science hoping it would have a reference, but there is nothing there. I don't have Brown's (1953) report, but it should say if the introduction was prior to 1953. Another possible source of the correct date is a report by Courtenay and Meffe in Meffe and Snelson's (1989) book on livebearer ecology and evolution. My copy disappeared with a student who evidently needed it badly ;-) . I've checked about 40 references this morning, and not found the date, just secondary and tertiary statements about the fish being introduced.
BTW, people tell me that Amazon's are difficult to find in the San Marcos R. these days, and have been ever since the extreme floods of the late nineties. If the floods are responsible, that would be one of the only incidences known in which floods actually altered the fish fauna of a stream.
I haven't seen Doug's report either, but most references (for example, Page and Burr's Peterson guide) simply report the Amazon as being "probably introduced" in the Nueces. The original reports from the thirties (by Carl Hubbs and Robert Rush Miller) describing the fish and reporting on its unisexuality make no mention of a population in the Nueces. Clark Hubb's Texas checklist states unequivocably but without attribution that the population in the Nueces was introduced. Whether Amazons occur in the tiny handful of streams (Santa Gertrudis Creek, Petronila Creek, Los Olmos Creek) tributary to Laguna Madre in the hundred miles between the Nueces and the Arroyo Colorado I do not know. I know I have never taken them from those streams, but my sampling has been very limited. Amazon mollies reportedly occur in ditches and ponds on N. Padre and Mustang Islands today. If they are absent from those streams, that would suggest on zoogeographic grounds that the Nueces population is introd
Brown's association of molly numbers with winter water temperatures in the streams mentioned is interesting. Sailfin mollies and formerly Amazon mollies were super abundant in the San Marcos in the 1990s, and the San Marcos, like the Comal but unlike the Guadelupe or the _MODERN_ (20th century) San Antonio is essentially a giant spring run with very nearly year round constant temperature. At San Marcos, Texas people swim in the San Marcos essentially year round -- Texans, not just Canadians on vacation. I don't know the temperature limits for mollies, but in the RGV, when cold fronts would kill blue tilapia by the thousands in ditches, I never found a dead molly. I do understand that critical temps do not necessarily indicate the minimum temps that can be inhabited, but it seems hard to me to reconcile what I know about mollies and what I know about the San Marcos with a temperature limitation for them.
Thanks for bringing these points up.
Dave
David L. McNeely, Ph.D., Professor of Biology
Langston University; P.O. Box 1500
Langston, OK 73050; email: dlmcneely-in-lunet.edu
telephone: (405) 466-6025; fax: 405) 466-3307
home page http://www.lunet.edu/mcneely/index.htm
"Where are we going?" "I don't know, are we there yet?"
----- Original Message -----
From: "Hoover, Jan J ERDC-EL-MS" <Jan.J.Hoover-in-erdc.usace.army.mil>
Date: Monday, February 7, 2005 12:36 pm
Subject: RE: NANFA-L-- Amazon Mollies
> Dave McNeely wrote:
> >>>Both species of mollies-in-San Marcos are introduced -- the
> sailfins from
> southern Louisiana, the Amazons from far S. Texas. The Amazon
> story-in-San
> Marcos is an interesting one. They were accidentally released
> from a
> traveling display of live Texas wildlife being taken around the
> state for
> educational purpose by the Texas Game and Fish Commission (now a
> part of the
> Texas Parks and Wildlife Department) that was housed in a trailer
>-in-the fish
> hatchery there. It is unclear when the sailfins were released --
> maybemultiple times.<<<
>
> Dave -
>
> What year did that happen ? Doug Martin wrote a paper on Amazon
> mollies in
> the Nueces River in 1964 for the Texas Journal of Science (which I
> have not
> yet seen) and I was wondering if it was prior to that.
>
> Re sailfin mollies - I posted this once before but it may be of
> interest -
> A 1953 article by William H. Brown (Texas Game and Fish
> Commission) notes
> that sailfin mollies were accidentally stocked in the San Antonio
> River when
> a 1939 flood washed out some fish ponds in which E.E. Shiner was
> raisingthem. Between 1932 and 1940, C.H. Burnstein stocked
> sailfins in the Comal
> River. Mollies were unknown-in-that time from the San Marcos, but
> in 1944,
> mollies were used as bait and released several times in the San
> Marcos.Brown notes that numbers of mollies were (in 1952) highest
> in the San
> Antonio, moderate in the Comal, low in the San Marcos, and lowest
> in the
> Guadalupe - and associated the trend with history of stocking and
> winterwater temperatures.
>
>
>
>
>
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