Sturgeon biodiversity and conservation

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Environmental Biology of Fishes 48: 209–219,1997. © 1997 Kluwer Academic Publishers. Printed in the Netherlands. Present status of commercial stocks of sturgeons in the Caspian Sea basin Raissa P. Khodorevskaya, Galina F. Dovgopol, Olga L. Zhuravleva & Anatolii D. Vlasenko Caspian Fisheries Research Institute, 1 Savushkina st., Astrakhan 414056, Russia Received 2.8.1994 Accepted 19.3.1996 Key words: beluga sturgeon, Huso huso, Russian sturgeon, Acipenser gueldenstaedtii, stellate sturgeon, Acipenser stellatus, population size, artificial propagation, pollution, poaching Synopsis Catches for the last 25 years are analyzed for beluga Huso huso, stellate sturgeon A. stellatus and Russian sturgeon Acipenser gueldenstaedtii, which are the three commercially important species of sturgeons found in the Caspian Sea Basin. Population sizes for generations born between 1961 and 1970 are estimated, and found to depend on natural reproduction and the number of young fish stocked annually from sturgeon hatcheries located in the Volga River Delta. A ban on sea fishing from 1962 to 1991 positively impacted the number and total biomass of commercial stocks. Sturgeon growth rates depend on water levels in the Caspian Sea. In order to preserve Caspian Sea sturgeon populations, it will be necessary to coordinate efforts of all countries surrounding the Caspian Sea to achieve rational harvests, preserve juveniles, and produce at least 100 million juveniles annually from hatcheries. Introduction Recently, 80 to 90 percent of the world’s sturgeon catch was taken from the Caspian Sea Basin, mainly from the Volga River (Barannikova et al. 1995). The Volga River and Caspian Sea are home to three commercial species, the beluga (Huso huso, see Pirogovskii et al. 1989), Russian sturgeon (Acipenser gueldenstaedtii, see Vlasenko et al. 1989a), and stellate sturgeon (A. stellatus, see Shubina et al. 1989), in the Russian (northern) part of this basin. A fourth commercial species, the Persian sturgeon (A. persicus, see Vlasenko et al. 1989b), inhabits mostly the southern (Iranian) part of the Caspian Sea and the rivers entering into it. Acipenser persicus is not discussed in this paper because of lack of data. The natural reproduction of commercial sturgeon species decreased in the Volga River after the Volgograd Dam was built between 1958 and 1960 (Figure 1). The dam prevents sturgeons from reaching their main spawning grounds. At present, the Ural River is the only large river entering the northern part of the Caspian Sea in which natural reproduction still occurs. Sturgeons no longer use the Kura and Terek rivers, where spawning previously occurred (Berg 1948). In this paper, we report on population changes in sturgeon stocks in the Caspian Sea from the early 1960s until 1994 based on data published in Dyuzhikov (1960), Shilov (1966), Khoroshko (1967,1970), VIasenko (1979,1990), Slivka et al. (1982), Khodorevskaya (1986,1992), Veshchev & Novikova (1988), Veshchev (1991a, b), Veshchev et al. (1992), Raspopov (1992, 1993), Dovgopol et al. (1993), Novikova (1993), Raspopov et al. (1994), Khodorevskaya et al. (1995), and Levin (1995). Also, the present status of natural reproduction in the Volga and the Ural rivers is described.
210 Figure1. Map showing lower portions of the Volga and Ural rivers, northern part of the Caspian Sea, and adjacent regions referred to in text. Other river systems historically used by the three commercially important species of sturgeons (Huso huso, Acipenser stellatus, and A. gueldenstaedtii) are labeled. Harvest trends during the last 40 years Prior to 1951, commercial sturgeon fishing concentratedin the Caspian Sea (Korobochkina 1964). Following recommendations to concentrate harvest to only the lower reaches of the Volga River (Derzhavin 1947), a ban on sea harvest was instituted. The only sturgeon taken in the Caspian Sea were as a by-catch to other fishes. The introduction of plastic nets in the late 1950s for harvest in the Caspian Sea greatly increased in the number of young sturgeons caught as by-catch. In 1957, of the total 2.6 million sturgeons harvested in the northern Caspian Sea, 1.8 million were young sturgeons, and in 1959–1961, the by-catch of young sturgeons reached 2-3 million (Korobochkina 1964). From 1962 until 1991, sturgeons were not harvested legally in the northern part of the Caspian Sea. For the last 35 years, natural and artificial reproduction contributed to the total commercial sturgeon stock in the Caspian Sea (Barannikova 1995). Sturgeon population sizes also depend on the volume of harvest, the construction and operation of dams, water consumption for irrigation and industry, and impacts of pollution. All three commercially important species of sturgeons now have fewer spawning fish migrating into the Volga and Ural rivers than in the past. Russian and beluga sturgeons no longer use the Kura, Terek and Sulak rivers, although small runs of stellate sturgeons still enter into the Terek and Sulak rivers to spawn. The Volga River and its delta are the most important areas in terms of commercial harvest. About 75% of the total sturgeon catch in the Caspian Sea basin comes from this area, with Russian sturgeon providing 60–70% of this total. Until recently, stellate sturgeon made up about 30% of the catch in the Volga River. Beluga constituted 5.0–6.0% of the catch. Between 1976 and 1981, Russian sturgeon were taken about four times more frequently than
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Sturgeonbiodiversity and conservati
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Sturgeon biodiversity and conservat
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Contents Prelude to sturgeon biodiv
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Portraits of three juvenile sturgeo
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10 I like this volume for other rea
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12 Figure 4. Paul Vecsei on the Fra
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14 In addition to our primary affil
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16 Figure 1. Leo Semenovich Berg, i
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18 fish fauna, Berg changed the nam
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20 history and evolution of sturgeo
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22 der Gattung Acipenser. Ann. Wien
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The three major commercial species
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26 the sense of Gans 1986) which we
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28 Few workers ever accepted the Al
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30 Figure3. Tree of ing craniates s
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32 Family †Chondrosteidae †Chon
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34 Figure 7. Aspects of the feeding
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36 Figure 9. The living North Ameri
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38 Figure 11. A large specimen of k
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40 Figure 13. Map of eastern Europe
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42 Figure17. Preliminary cladogram
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44 certainly warrants much addition
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46 could be reliably scored in at l
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48 Figure 20. Scanning electron mic
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50 atic because acipenseriform larv
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52 defining Acipenseroidei, which w
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54 other Acipenseriformes, is prese
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56 Figure 22. Functional morphology
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58 acter 15). One to three branchio
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60 Figure 24. Direct evidence for p
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62 ton (Traquair 1887, Woodward 189
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64 Northcutt 1978, New &Bodznick 19
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66 attempt to predict further chang
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68 manni Bogdanov under artifical e
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70 Patterson, C. 1975. The braincas
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a b Sturgeons of the Danube River a
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74 ground swell of interest in stur
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76 Materialsand methods Phylogeneti
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78 Acipenseridae. Some species of A
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80 Figure 3. Jugal of representativ
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82 Figure 5. Extrascapular bones of
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84 Figure 7. The opercular series o
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86 indications from Gardiner & Scha
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88 Figure 9. Left scapulocoracoid o
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90 Character 17. Basipterygial proc
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92 quair 1887), † Gyrosteus (Wood
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94 Figure 13. Ventral hyobranchial
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96 Figure 15. Basitrabecular proces
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98 Figure 17. Ventral rostrum of Ps
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100 Figure 18. Dorsal bones of the
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102 Figure 19. Ventral rostral bone
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104 sess thin jaws. † Paleopsephu
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106 ing the rostral nerves (grn). T
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108 ever, in Acipenser they are not
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110 Figure 24. Ventral axial skelet
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112 Figure25. Gill rakers of repres
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114 more elongate than a small, inn
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116 Chavacter 66. Cleithral wall pr
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118 tentially untenable. Characters
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120 ideal for retaining small prey
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122 benthic prey fauna continued wi
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124 Future research on Acipenserida
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126 dem Yangtsekiang und über die
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128 Within Acipenseriformes, all wo
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130 Table 1 (Continued). Species Ch
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132 rent views on paleogeography wi
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134 nucleus in species investigated
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136 cated loci is much lower, only
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138 Figure 1. A schematic represent
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140 sue). Our data were polarized u
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142 DNA sequence alignment and phyl
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144 tions of codons. For comparable
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146 Figure 5. The single parsimony
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148 A. brevirostrum; and (4) both c
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› 150 References cited Asahida, T
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152 Golubtsov, A.S. &E. Yu. Krysano
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154 shovelnose sturgeon (Scaphirhyn
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Portraits of a juvenile Huso huso 2
Page 159 and 160: 158 which have quickly eliminated s
Page 161 and 162: 160 ing the length of the spleen (i
Page 163 and 164: 162 Hochleithner, M, 1995. Gesellsc
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Page 168 and 169: Environmental Biology of Fishes 48:
Page 170 and 171: › › bly related to themal requi
Page 172 and 173: strong homing capabilities, althoug
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Page 176 and 177: 175 sible to make meaningful compar
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Page 180 and 181: Some have asserted (e.g., Yakovlev
Page 182 and 183: › › › › › › cens in Nor
Page 184 and 185: 183 ces: Acipenseridae); threats an
Page 188 and 189: Figure 2. Distribution of the belug
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Page 192 and 193: 191 Figure 5. Unusually large speci
Page 194 and 195: › › Acipenser gueldenstaedtii -
Page 196 and 197: › › ∨ ∨ cíkovo Holcík et
Page 198 and 199: the first draft of this paper and t
Page 200 and 201: Malesevics, E. 1892. Loszoncz faun
Page 202 and 203: Environment Biology of Fishes 48: 2
Page 204 and 205: 203 caught here. You would not beli
Page 206 and 207: 205 from the Vienna basin to the Ur
Page 208 and 209: and improved by Vadim Birstein and
Page 212 and 213: 211 Population changes and status B
Page 214 and 215: However, since 1979, the number of
Page 216 and 217: 215 Influence of dams on natural re
Page 218 and 219: 217 (5) Since 1990, declines in stu
Page 220 and 221: genesis in Caspian sturgeons. Vopro
Page 224 and 225: 223 Figure 1. The range of the Sibe
Page 226 and 227: 225 the Siberian sturgeon range in
Page 228 and 229: 227 basins: 1401 and 504 metric ton
Page 230 and 231: 229 Kirillov, F. N. 1972. Fishes of
Page 234 and 235: 233 Figure 2. Acipenserid fishes of
Page 236 and 237: 235 same generation mature and spaw
Page 238 and 239: cytes degenerate, then the age of t
Page 240 and 241: 239 Krykhtin, M.L. 1986. The rate o
Page 244 and 245: 243 Province. Also starting in the
Page 246 and 247: 245 counted for 87.4% near Zhaoxing
Page 248 and 249: ymous 1988, Lin & Zeng 1987, also s
Page 250 and 251: 249 Figure 4. Size frequency distri
Page 252 and 253: 251 mous 1988). A sample of 54 fema
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259 of pertinent information that c
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261 weight (BW) and length (L) befo
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263 Bemis, W.E. & L. Grande 1992. E
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Environmental Biology of Fishes 48:
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267 Figure 1. Different states of g
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269 10.2 and 7.3% for stGTH I. and
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271 Figure 4. Approximate length an
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273 cultured Siberian sturgeon, A.
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plasma androgens (Moberg et al. 199
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277 River in 1973, as determined by
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281 Figure 2. Status of North Ameri
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283 wa, Louisiana, Oklahoma, and Vi
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285 presumably as a result of high
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287 state are closed to commercial
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289 and federal resource agencies w
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were considered a nuisance to comme
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295 Sport and commercial harvests o
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297 Acknowledgements I thank S. Whi
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301 Figure 1. Mitochondrial DNA hap
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303 sive closures and openings char
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305 Figure 4. Status of lake sturge
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as ‘absent’. Very few lake stur
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309 correspond to local populations
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Table1. Estimates ofthesize ofthe l
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Lower section of river the harvest
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tem, Wisconsin. pp. 135-146. In:F.P
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321 hierarchy that determines use o
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323 97 000 cultured 5 shortnose stu
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325 11568 eggs per kg body weight;
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327 data). This is sufficient time
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329 low Mactaquac Darn (river km 13
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331 would not change the basic rela
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tured Fish into existing population
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some areas, a small fall spawning m
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339 tic sturgeon occurred during th
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341 ly to severely degraded. Dredgi
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Commission (ASMFC) completed develo
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een prepared by the Atlantic Sturge
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349 Figure 1. Life intervals and se
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351 Figure 3. Life intervals and se
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353 (Buckley & Kynard 1981, Taubert
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355 from larva to juveniles appears
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357 The protracted period of Atlant
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Environmental Biology of fishes 48:
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361 By the early 1970s, A. sturio w
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363 Figure 3. Accidental captures o
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365 Table 1. Results of attempts to
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367 weight, this individual regaine
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Cryopresarvation of the sperm of Sa
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Part 3: Controversies, conservation
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375 ers and lakes was extremely con
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377 not found in the lower reaches
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379 cies (including stellate sturge
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Kessler, K. E 1872. On a remarkable
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Environment Biology of fishes 48: 3
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387 Figure I. Comparison of mtDNA c
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nate between S. albus and S. plator
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391 Figure 2. Gulf of Mexico rivers
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393 stock analysis, frequencies of
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necks on their populations. However
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Birstein, V.J. 1993. Sturgeons and
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Restricting fishing mortality to of
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and increasing total mortality to Z
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405 geon in the Suwanee River, Flor
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409 has been widely correlated with
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name the sturgeon or paddlefish spe
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413 Figure 2. Abundance and product
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415 managers and biologists have be
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geon (Acipener fulvescens) from the
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macroinvertebrate faunas, and obstr
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microhabitat diversity, and turbid
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Environmental Biology ofFishes 48:
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425 denied any contact with the poa
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429 and paddlefishes, particularly
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431 Table 1 Continued. A. oxyrinchu
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DNA primers (DeSalle & Birstein 199
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435 Smith, T.I.J. & J.P. Clugston.
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Species and subject index* 12SrDNA(
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439 hypoxia 206 irrigation 204,374,
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441 Gulf Sturgeon Recovery/Manageme
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†Protopsephurus biogeography 174
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