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56 GREAT BASIN NATURALIST MEMOIRS 197 some stability was achieved in water levels, it became possible to attempt management of water level to achieve a desired minimum an- nual population size. The desired minimum population size was established at 200 in an effort to insure that the population would not fall so low as to tend to accelerate toward ex- tinction. The present court-mandated level of 2.7 appears to be just maintaining minimum population size (Fig. 13, Table 4). This example illustrates the direct and rap- id impact on restricted native fishes which can result from even modest developments nearby. Often, as was true in this case, the developer may be almost entirely unaware of the consequences of his activities. For fishes living in restricted environments, this lack of awareness can mean extinction. DISCUSSION It is apparent that the full variety of rea- sons for becoming threatened are exemplified No.3 among the endangered or threatened fishes of the West. The legitimate question arising from this and every consideration of endan- , gered species is "Why bother? What good are they?" The answers to those questions, I believe, must include at least two parts: (1) because it is to our own self-interest to do so, and (2) because our society's values, as ex- pressed through federal law, require us to "bother." The second answer has been and will continue to be debated and perhaps modified. The. first is really the core of the endangered species debate. The argument, simplified, I believe, involves at least the fol- lowing considerations. Because populations are dependent upon and interact within eco- systems, extinction is an indication of a signif- icant change in the ecosystem-in general, a reduced capability to support life or at least to support diversity. The fact that an endan- gered species is involved may, therefore, be an indication that the long-term carrying ca- pacity of an ecosystem may be exceeded (the arg Th, abo in par be de! del j ver ab mo ten pre int~ to thi~ tWI lar zat 19~ pe~ the hol soc tor cn ma arc tht lisl TABLE 4. Estimated population size of the Devils Hole pupfish (Cyprinodon diabolis) in Devils Hole, Nye County, Nevada, 1972-1978. Estimates are the maximum number of fish actually counted visually during standardized at- tempts at counting the entire population. Data prior to 4 June 1974 were taken by Dr. R. R. Miller and subsequently by J. E. Deacon. Population Population Population Date estimate Date estimate Date estimate 1972 1975 1977 6 April 127 22 Jan 208 20 Jan 324 2 June 248 20 Feb 159 24 Feb 276 28 July 286 18 Mar 148 24 Mar 198 27 Sept 191 10 Apr 158 5 May 210 14 Nov 199 19 May 201 6 June 221 16 June 262 27 June 359 1973 30 July 278 II July 330 10 Jan 252 20 Aug 294 15 Aug 553 20 Feb 191 30 Sept 260 26 Sept 490 28 Mar 208 21 Oct 279 28 Nov 381 12 June 184 25 Nov 261 30 Aug 253 16 Dec 246 1978 6 Nov 244 16 Jan 296 1976 2 Mar 225 1974 17 Feb 228 16 Mar 219 5 Feb 163 3 Mar 180 24 Apr 223 29 Apr 143 30 Mar 181 19 May 242 5 June 239 27 Apr 195 19 June 274 11 July 250 18 May 203 20 July 326 22 Aug 286 22 June 316 11 Aug 388 15 Sept 302 2 Aug 345 13 Sept 358 9 Oct 277 24 Sept 410 18 Oct 441 19 Nov 250 18 Oct 385 11 Dec 361 18 Dec 238 3Dec 334 no' cie wa di.. pl~ ula nif SOl thr mt Ba me enl set th< dr: stil in of iZt ca: suI