My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
8147
CWCB
>
UCREFRP
>
Copyright
>
8147
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
7/14/2009 5:01:47 PM
Creation date
5/20/2009 1:33:19 PM
Metadata
Fields
Template:
UCREFRP
UCREFRP Catalog Number
8147
Author
Scoppettone, G. G.
Title
Interactions Between Native and Nonnative Fishes of the Upper Muddy River, Nevada.
USFW Year
1993.
USFW - Doc Type
\
Copyright Material
YES
There are no annotations on this page.
Document management portal powered by Laserfiche WebLink 9 © 1998-2015
Laserfiche.
All rights reserved.
/
10
PDF
Print
Pages to print
Enter page numbers and/or page ranges separated by commas. For example, 1,3,5-12.
After downloading, print the document using a PDF reader (e.g. Adobe Reader).
Show annotations
View images
View plain text
<br />NATIVE AND NONNATIVE STREAM FISH INTERACfIONS <br /> <br />603 <br /> <br />to diet among species, food items consumed were <br />quantified by frequency of occurrence (Windell <br />1971). <br />Predation. - I compared the relative propensity <br />of adult Moapa White River springfish, shortfin <br />mollies, and mosquito fish to prey on fish larvae. <br />I used larval suckers Catostomus sp. (9-10 mm <br />TL) from the Truckee River, Nevada, as a sur- <br />rogate for Moapa dace larvae. Catostomus larvae <br />were used in lieu of Moapa dace because of their <br />unlisted status, availability, and tendency to oc- <br />cupy habitat similar to that of larval Moapa dace <br />(Moyle and Baltz 1985). Two experiments were <br />run on 11 July and two on 22 July 1991. For each <br />experiment, three adults each of Moapa White <br />River springfish, shortfin molly, and western mos- <br />quitofish were used. Moapa White River spring- <br />fish ranged from 1.4 to 3.8 g and 42 to 60 mm <br />TL, shortfin mollies from 1.3 to 3.5 g and 45 to <br />58 mm TL, and western mosquitofish from 0.7 to <br />1.5 g and 39 to 50 mm TL. Test fish were captured <br />from the upper Muddy River system 1-6 d prior <br />to the experiment. Each experimental group re- <br />ceived the same treatment. Tanks were 57-L <br />aquaria. Controlled water temperature ranged from <br />27.5 to 30.0oC. Each adult was placed in a separate <br />test tank and starved for 24 h prior to the exper- <br />iment; then 10 sucker larvae and 5 brine shrimp <br />Artemia sp. were placed in each of the nine ex- <br />perimental tanks and in three control tanks that <br />contained only larvae and brine shrimp. Artemia <br />were added to help determine if fish were habit- <br />uated and willing to eat alternative prey if avaU- <br />able. Remaining Catostomus larvae and Artemia <br />were counted every 2 h over an 8-h period. <br /> <br />Results <br /> <br />Relative Abundance <br /> <br />Western mosquitofish adults were the least <br />abundant nonnative fish species in the four Moapa <br />dace reproduction or nursery reaches; densities <br />ranged from 0.1 fishlm at Muddy Spring to 3.5 <br />fishlm along South Fork Stream (Table 1). Short- <br />fin molly predominated at two sites and Moapa <br />White River springfish at the other two. Shortfin <br />molly was the most numerous species in the entire <br />area, numbering an estimated 37,800 adults com- <br />pared with estimates of 16,600 adult Moapa White <br />River springfish, fewer than 3,000 adult western <br />mosquitofish, and 2,200 Moapa dace. These nu- <br />merical estimates are only of populations in the <br />tributaries in which Moapa dace are known to <br />reproduce, not the total adult populations. <br /> <br />TABLE I.-Densities of Moapa dace, Moapa White <br />River springfish, shortfin molly, and western mosqui- <br />tofish adults in four known Moapa dace nursery streams. <br /> <br /> Estimated <br /> population and <br /> 95% conli.dence <br />Species interval Fish/m <br /> Refuge Stream <br />Moapa dace 250 0.2 <br />White River springJish 5,544 :!: 583 3.4 <br />Shortli.n molly 16,104 :!: 2,059 10.0 <br />Western mosquitofish Scarce <br /> Upper Apcar <br />Moapa dace 200 l.l <br />White River springfish 2,979 :!: 476 16.0 <br />Shortfin molly 1,391 :!: 253 7.5 <br />Western mosquitoli.sh 87 :!: 43 0.5 <br /> South Fork <br />Moapa dace 300 0.4 <br />White River springfish 4,800 :!: 925 6.3 <br />Shortli.n molly 18,700:!: 2,175 24.5 <br />Western mosquitofish 2,650 :!: 725 3.5 <br /> Muddy Spring <br />Moapa dace 1,450 1.8 <br />White River springJish 3,326 :!: 1,082 4.1 <br />Shortfin molly 1,637 :!: 264 2.0 <br />Western mosquitoli.sh 106 :!: 54 0.1 <br /> <br />Spatial Overlap in Microhabitat <br /> <br />Adult Moapa dace were associated with greater <br />mean water velocity and greater focal point ve- <br />locity than their cohabitants (Table 2). They also <br />had the greatest niche breadth for these spatial <br />categories. Adult Moapa dace and Moapa White <br />River springfish were more benthically oriented <br />and in deeper water than adults of the two non- <br />natives. Moapa dace larvae and juveniles oc- <br />curred in lower focal point water velocities than <br />adults, in shallower water, and generally higher in <br />the water column. <br />Spatial habitat overlap of native and nonnative <br />fishes was moderate to nil (Table 3). Moapa dace <br />overlap was greatest for its larvae and juveniles <br />with shortfin molly adults (44 and 45%, respec- <br />tively). Moapa White River springfish overlap was <br />greatest for its larvae with juvenile shortfin mol- <br />lies (47%). <br />Adult Moapa dace and Moapa White River <br />springfish showed no significant differences in <br />habitat use between areas where nonnative species <br />were present or absent (all P's > 0.38). Although <br />the sample sizes were small, the data suggest that <br />no major shifts in habitat use have been forced <br />on the two native species by the introduced fishes. <br />Sample sizes were too small to test the effects on <br /> <br />
The URL can be used to link to this page
Your browser does not support the video tag.