Y SYMPOSIUM INTERNATIONAL SUR L'ESTURGEON

Piacenza, Italie du 8 au 11 juillet 1997

Québec gr. Direction de la faune et des habitats

RAPPORT DE MISSION

3e Symposium international sur l'esturgeon

Piacenza, Italie du 8 au 11 juillet 1997

par

François Caron

Ministère de l'Environnement et de la Faune Juillet 1997 121 Gouvernement du Québec Ministère de l'Environnement et de la Faune Direction de la faune et des habitats iii

TABLE DES MATIÈRES

Page

TABLE DES MATIÈRES iii 1.OBJECTIFS DE NOTRE PARTICIPATION 1 2. UN DÉBUT DE CONFÉRENCE CHAOTIQUE 2 3. L'ÉTAT DES ESTURGEONS DANS LE MONDE 3 3.1. Les espèces anadromes sont en piètre état 3 3.2. L'élevage en captivité est en croissance en Europe 3 3.3. Les ensemencements sont un fiasco presque généralisé 3 4. COMBIEN Y A-T-IL D'ESPÈCES D'ESTURGEON 9 3 5. EFFETS NÉGATIFS D'UNE TAILLE MINIMALE DE CAPTURE 4 6. EST-CE QUE LES ESTURGEONS CHANTENT ? 4 7. QU'AI-JE APPRIS D'UTILE ? 5 7.1. Frayères et lieux de concentration des adultes 5 7.2. Frayère : endroit très précis et fragile 5 7.3. Stratégie d'exploitation pour l'esturgeon de lac nordique : une année sur cinq ? 5 7.4. Les esturgeons mangent même en période de fraie... d'autres moyens de capture pourraient être mis à l'essai 5 8. L'ESTURGEON ET LA PÊCHE SPORTIVE 6 9. LES ESTURGEONS ENVAHISSENT L'HÉMISPHÈRE SUD 6 10. LES ÉLEVAGES : DES POUR ET DES CONTRE' 6 11.QU'EST-CE QUE LE CAVIAR 9 7 12. REPRÉSENTATION QUÉBÉCOISE À CE SYMPOSIUM 7 13. PROCHAIN SYMPOSIUM 7 14. ÉPILOGUE : DECOUVERTE DE GENITEURS DANS LE FLEUVE SAINT- LAURENT 8 ANNEXE 1 9 ANNEXE 2 23 ANNEXE 3 35 1

I. OBJECTIFS DE NOTRE PARTICIPATION

L'esturgeon est un poisson quasi mythique : les plaques osseuses qui garnissent son corps, son apparence générale assez particulière dont la position de la bouche, la présence de barbillons et la forme de sa queue, ainsi que la grande taille que peuvent atteindre certaines espèces sont autant d'éléments qui contribuent à sa réputation de « poisson fossile vivant ».

Recherché depuis fort longtemps pour son caviar (oeufs salés extraits de la femelle que l'on vient d'ouvrir), l'esturgeon a fait l'objet de nombreuses études, particulièrement en Europe. Les Russes ont d'ailleurs commencé l'ensemencement d'alevins en 1875 dans le but d'augmenter la pêcherie. Un siècle plus tard, les pêcheries se sont effondrées à presque rien, quelques espèces sont disparues, plusieurs sont menacées et le marché est largement soutenu par les élevages et les ensemencements. Cette situation a, bien sûr, alerté les gestionnaires et les scientifiques qui ont mis sur pied, depuis une dizaine d'années, symposiums, colloques et conférences pour échanger les nouvelles connaissances sur des poissons de cette famille.

Au Québec, notre pêcherie sur l'esturgeon noir est singulière. On n'y capture que des poissons sub-adultes, et les reproducteurs tout comme les alevins étaient, à toute fin pratique, introuvables à ce jour. Toutefois, le projet de l'été 1997 nous permet de découvrir un premier site de reproducteurs dans le Saint-Laurent, ce qui ouvre la voie à la découverte de sites essentiels pour cette espèce. En plus du fait que l'esturgeon noir soit complètement disparu de la pêcherie de l'estuaire pendant près de 10 ans avant de reprendre et d'atteindre des niveaux records au cours des dernières années, cette situation soulève un intérêt certain pour une meilleure compréhension et une gestion accrue de ce poisson.

Les objectifs de notre participation à ce symposium étaient les suivants :

— recueillir les nouvelles informations sur les travaux en cours, ailleurs dans le monde; — s'informer particulièrement sur les aspects qui pourraient nous permettre de progresser plus rapidement dans nos travaux; — diffuser ces informations aux autorités et aux collègues de travail concernés par le sujet.

On retrouvera en annexe :

— La version préliminaire de notre présentation; la version finale devra être déposée fin août et ceux qui voudraient suggérer des corrections et améliorations sont invités à le faire au plus tôt. — La liste des présentations par session et par pays. — Quelques résumés qui m'ont semblé d'un intérêt particulier. 3

3. L'ÉTAT DES ESTURGEONS DANS LE MONDE

Le titre de ce chapitre est certes ambitieux : impossible de tirer une seule généralité de 25 espèces, d'autant plus que les présentations n'ont pas couvert toutes les espèces. Néanmoins, je présente ici certaines généralités qui me semblent valables.

3.1. Les espèces anadromes sont en piètre état

— Quelques espèces ( ? ) sont disparues au cours de ce siècle.

— Plusieurs sont artificiellement soutenues par des ensemencements.

Les principales causes de cet état sont la disparition des habitats essentiels que ce soit par la pollution, la construction de barrage ou la transformation du milieu, ainsi que la surexploitation. L'intérêt (et le capital !) pour le caviar est très néfaste pour certaines espèces puisqu'il conduit à tuer la poule aux oeufs d'or. Dans certains pays comme la Russie, l'Iran et la Roumanie, il semble que le braconnage soit élevé et hors de contrôle, ce qui n'arrange pas la situation.

3.2. L'élevage en captivité est en croissance en Europe

Il s'élève des esturgeons en captivité depuis plus d'un siècle. Le déclin des stocks et le prix élevé des esturgeons ont forcé le développement de cette activité en tout premier lieu pour l'élevage de juvéniles à des fins de soutien de la pêche.

Au cours des vingt dernières années, des études ont été menées pour élever des esturgeons en captivité pour la vente directe du caviar, de la chair ou de poissons vivants pour des fins de pêche. Ces techniques permettent maintenant l'élevage de trois espèces et d'un hybride en France, en Allemagne et en Italie.

33. Les ensemencements sont un fiasco presque généralisé

La preuve est faite qu'on ne peut pas détruire l'habitat essentiel, polluer, surexploiter et soutenir des stocks par des ensemencements. Plusieurs soulèvent aussi de sérieuses questions sur l'effet de ces pratiques massives sur la génétique des stocks, pour l'esturgeon comme pour les salmonidés d'ailleurs.

4. COMBIEN Y A-T-IL D'ESPÈCES D'ESTURGEON ?

Le sujet semble soulever des passions. Officiellement, il y aurait 25 espèces dans la famille des Acipenséridae mais il y a définitivement beaucoup de confusion dans la description des espèces. Les caractéristiques morphologiques semblent très variables sur une même espèce, ce qui a sans doute contribué à décrire comme « espèce distincte » des poissons d'une même espèce mais qui sont éloignés géographiquement (voir le cas de 5

rapprochent des sons plaintifs des baleines et il croyait, jusqu'ici, qu'il s'agissait d'une fumisterie. Chez les oiseaux et les grenouilles, il existe des méthodes d'estimation d'abondance reliées à l'abondance des chats. Serait-ce un développement que nous verrons dans le futur !

7. QU'AI-JE APPRIS D'UTILE ?

Il y a trop peu de connaissances sur l'esturgeon noir pour nous permettre de relier certaines informations à notre situation dans le Saint-Laurent. Je tente tout de même de réunir quelques idées qui me semblent utiles, surtout dans le contexte où nous recherchons les lieux de fraie et d'élevage des alevins.

7.1. Frayères et lieux de concentration des adultes

Les esturgeons se rassemblent dans des fosses et se déplacent rapidement vers leur lieu de fraye qui peut être situé plusieurs kilomètres en amont. Lorsqu'une femelle est prête à frayer, elle est alors accompagnée de plusieurs mâles et semble frayer complètement en quelques heures.

7.2. Frayère : endroit très précis et fragile

La superficie de la frayère est très réduite et possède des caractéristiques très particulières : écoulement, granulométrie, température de l'eau, mais aussi complexité du courant, pH, et conductivité. Cet habitat est donc très fragile et difficile à localiser. Des modifications au débit peuvent éliminer la reproduction.

7.3. Stratégie d'exploitation pour l'esturgeon de lac nordique : une année sur cinq ?

Dans les populations nordiques, l'âge à la reproduction est très élevé et les géniteurs sont tellement sensibles à l'exploitation qu'ils ne peuvent supporter une exploitation soutenue. C'est le cas, entre autres, de quelques populations dans la région 10. Au Wisconsin, on pratique, dans ce cas, une exploitation en « rotation », soit une année sur cinq, ce qui permet une pêche intéressante sans surexploiter le stock.

7.4. Les esturgeons mangent même en période de fraie... d'autres moyens de capture pourraient être mis à l'essai

L'esturgeon blanc se capture à la ligne, même peu de temps avant la fraie. Il semble que d'autres espèces d'esturgeon font de même. On les capture alors à la ligne dormante, en utilisant comme appât de l'anguille ou du saumon.

Cette méthode pourrait être mise à l'essai pour la capture de l'esturgeon noir, surtout dans l'estuaire fluvial où il est très difficile de faire tenir des filets aux endroits où l'on croit 7

11. QU'EST-CE QUE LE CAVIAR ?

Produit de haute gastronomie, le caviar est constitué des oeufs non fécondés d'esturgeon qu'on extrait directement de la femelle et qu'on sale rapidement. — Valeur sur le marché : qualité moyenne : 170,0 $US/kg; qualité supérieure : 700,0 à 2700,0 $US/kg; première qualité : 4200,00 $US/kg.

— Production par femelle : 15 à 20 % de son poids.

— Provenance : 90 % de la mer Caspienne, principalement de Russie et d'Iran.

— Demande du marché : croissante surtout aux États-Unis, dans les pays de l'Union européenne, en Suisse et au Japon.

— Problématique : les stocks de la mer Caspienne sont en forte baisse. L'élevage pourrait prendre la relève.

12. REPRÉSENTATION QUÉBÉCOISE À CE SYMPOSIUM

Le comité de sélection du Symposium avait accepté, en plus de la présentation orale que j'ai préparé avec Serge Tremblay, un poster soumis par Guy Trencia et Guy Verreault qui portait sur la gestion de la pêcherie de l'esturgeon noir dans le Saint-Laurent. Des raisons budgétaires ont fait en sorte que je sois le seul représentant à me rendre sur place. Néanmoins, le texte qui résumait le poster a été remis à chaque participant au moment de l'inscription.

De plûs, Serge Tremblay était coauteur d'un poster avec un groupe de Français sur les travaux portant sur l'esturgeon européen juvénile dans la Gironde et deux anciens étudiants d'université québécoise ont participé à la présentation de deux autres posters.

13. PROCHAIN SYMPOSIUM

Deux pays ont soumis leur candidature pour organiser le prochain symposium : les États- Unis, pour une date qui n'a pas été précisée et l'Iran, pour l'an 2000. ANNEXE 1 ticruie AND MANAGEMENT OP AN ExPLortz» POPULATI OF ATLANTIC STURGEON (Acipenser avyrietchus IN:THE LAWRENCE ESTUARY, Qutereic, CANAU

ranglieCaron: :and .Sérge Teenbla Ministère de l'Environnement et de la Faune, 150, boul. René-Lévesque Est (5`) QUÉBEC (QC), CANADA G1R 4Y1

RÉSUMÉ. L'esturgeon noir Acipenser oxyrinchus a été exploité commercialement dans l'estuaire moyen du fleuve Saint-Laurent jusqu'à ce jour, mais la pêcherie n'a jamais été restreinte avant 1994. Au cours des dernières années, les débarquements ont augmenté de plus de 50%, pour atteindre 120 tonnes en 1993, et l'âge médian des captures est passé de 11 ans à 6 ans.

Depuis 1994, nous avons adopté diverses mesures réglementaires dans le but de réduire les débarquements annuels à un niveau de 60 tonnes en 1998. Des études récentes, menées avec la collaboration des pêcheurs commerciaux, ont permis d'améliorer nos connaissances de cette pêcherie et de mesurer les effets des nouvelles règles de pêche, telles que les restrictions du nombre de filets de pêche, le contrôle de l'effort de pêche, la réduction de la saison et les limites de taille pour les captures. Nous avons également évalué le recrutement et la structure d'âge de la population. Les captures sont constituées uniquement de poissons sub-adultes (longueur à la fourche de 50-170 cm). Les adultes sont totalement absents des captures. Les dernières cohortes importantes qui soutiennent la pêche proviennent des années 1982, 1986 et 1988.

Les caractéristiques des captures varient selon les secteurs; dans la zone de faible salinité, près de 50% des captures ont une taille inférieure à 100 cm, alors que ce pourcentage est de 13% dans le secteur aval. La population d'esturgeon noir du fleuve Saint-Laurent se caractérise par un recrutement annuel variable, par une récolte élevée et par l'absence d'individus sexuellement matures dans la pêcherie. Les récentes mesures restrictives ont permis de réduire les captures, mais pas suffisamment pour atteindre notre objectif de gestion. Des études sont en cours pour localiser les aires de fraie et les habitats d'élevage des juvéniles. On porte désormais une grande attention à l'exploitation de cette population.

MOTS-CLÉS : Esturgeon noir, Acipenser wcyrinchus, commercial fishery, estuary, management, caractéristiques de population variant généralement de 10 à 30 m, et les filets sont relevés quotidiennement. Dans le secteur A, les pêcheurs déplacent fréquemment leurs engins de pêche pour utiliser les sites qui présentent momentanément des rendements plus élevés alors que dans la partie B, les pêcheurs utilisent généralement quelques sites de pêche pour toute la saison.

Des mesures sont prises sur un échantillonnage aléatoire des captures. Les mesures de poids et de longueur à la fourche étaient effectuées sur le terrain et on prélevait la nageoire pectorale droite du poisson pour faire, par la suite, la lecture d'âge selon la méthode prescrite par Kohlhorst et aL (1980). Une partie des poissons de grande taille ont été examinés pour en déterminer l'état de maturation sexuelle.

RÉSULTATS

Les débarquements sont caractérisés par trois grandes périodes : de 1940 à 1966, il se récolte annuellement de 20 à 40 tonnes d'esturgeon; de 1967 à 1975, l'esturgeon est alors presque totalement absent de la pêcherie, puis le volume des captures augmente rapidement pour dépasser 100 tonnes à partir de 1988 et atteindre 120 tonnes en 1993 (fig. 3), soit au moment où l'on observe une demande accrue pour la chair de ce poisson sur les marchés.

Au cours des dernières années, un suivi des débarquements a été mis en place dans le but de mieux caractériser l'activité de pêche et la nature des captures.

La longueur à la fourche des poissons capturés varie de 50 à 170 cm, avec une dominance marquée pour les poissons entre 80 et 140 cm (fig. 4). Les deux secteurs de pêche semblent exploiter des esturgeons appartenant à la même population. En effet, on retrouve essentiellement les mêmes modes de fréquence de longueurs dans les deux secteurs. Toutefois, la répartition des tailles des poissons est fort différente. Les individus de moins 100 cm (longueur à la fourche) représentent près de 50 % des captures dans le secteur A et seulement 13 % dans le secteur B (fig. 4). La clé âge-longueur permet de constater qu'il s'agit là de poissons dont l'âge varie essentiellement entre 4 et 25 ans (fig. 5, 6). L'examen des gonades révèle que ces poissons, même parmi ceux de grande taille, sont tous des sub-adultes immatures.

Le suivi des débarquements a permis de constater que l'âge médian des esturgeons capturés, qui était d'environ 12 ans de 1984 à 1988, a chuté entre 6 et 8 ans de 1989 à 1994, soit au même moment où s'accroissait la récolte (fig.7 ). D'après les lectures d'âge, on constate que la pêche, au cours des dernières année, est soutenue principalement par trois classes d'âge très fortes, soit les poissons issus de la fraye de 1982, de 1986 et de 1988 (fig. 8).

MESURES RÉCENTES DE GESTION

L'augmentation récente du nombre de captures liée à la diminution de l'âge médian des poissons ont entraîné la mise sur pied d'une série de mesures visant à réduire le nombre de captures en laissant s'échapper un plus grand nombre de petits spécimens ainsi que les poissons approchant l'âge de la reproduction. Avant 1994, les seules mesures de conservation utilisées consistaient à limiter le nombre de permis (35), et la grandeur minimale de maille pour les filets était de 18 cm, bien que la majorité des pêcheurs utilisaient des filets de 20 cm (grandeur de maille étirée). L'absence de captures de géniteurs ne nous permet que de spéculer sur l'âge à maturité sexuelle de ce stock d'esturgeon à la limite nord de son aire de distribution. Selon Magnin (1963), l'âge à la reproduction des esturgeons noirs dans le Saint-Laurent serait de 22 à 24 ans pour les mâles, et de 27 à 28 ans pour les femelles, soit un âge plus avancé que ce qui est connu pour des populations plus au sud de son aire de distribution. Dans le fleuve Hudson, à environ 600 km au sud du Saint-Laurent, les mâles sont sexuellement matures à l'âge de 15 ans, à. une taille de 160 cm, et les femelles, à l'âge de 18 ans, à une taille de 189 cm (Doroshov et al. 1993), certains mâles pouvant même maturer à une taille inférieure (Doroshov et al., 1994).

La disparition de l'esturgeon noir dans les pêcheries, entre 1967 et 1975, constitue une source de préoccupation. Pour l'instant, la cause exacte de cette absence de l'esturgeon n'a pas été démontrée avec certitude, mais il pourrait s'agir des conséquences du dragage du fleuve ou du dépôt de sédiments dans des zones de reproduction; de la pollution chimique du fleuve survenue à cette époque, particulièrement l'utilisation massive d'insecticides; de la surexploitation des adultes; ou d'une combinaison de ces facteurs.

Un programme de suivi des captures permet d'évaluer annuellement les mesures de gestion mises en place récemment. Un vaste programme, en cours, sur l'écosystème global du Saint-Laurent a permis de constater une amélioration certaine de la qualité de l'eau et des sédiments du fleuve au cours des 20 dernières années (Centre Saint-Laurent 1996). Le fait d'exploiter uniquement les sub-adultes offre la possibilité de maintenir une pêcherie à long terme à la condition qu'un certain nombre de recrues puissent échapper à la pêcherie et atteindre l'âge à la reproduction. Le suivi de la récolte devrait nous permettre de vérifier l'atteinte de nos objectifs et dè corriger le plan d'exploitation au besoin. De plus, il nous apparaît important de localiser les sites de fraie et d'élevage des jeunes esturgeons pour en assurer leur protection. LISTE DES FIGURES

Figure 1 : Distribution de l'esturgeon noir

Figure 2 : Localisation de la zone de pêche et des secteurs utilisés

Figure 3 : Évolution des débarquements d'esturgeons noirs dans l'estuaire du Saint-Laurent, 1940-1996

Figure 4 : Distribution des fréquences des longueurs d'esturgeons noirs capturés dans les secteurs A et B, 1994

Figure 5 : Distribution des fréquences d'âge des esturgeons noirs capturés dans le secteur A, 1994

Figure 6 : Relation âge-longueur des esturgeons noirs capturés dans le secteur A, 1994

Figure 7 : Évolution des débarquements et de l'âge médian des captures, 1984-1994

Figure 8 : Distribution des fréquences annuelles d'âge des captures d'esturgeons noirs, 1991- 1994 Fig. 4Distribution oflengthfrequenciesAtlantic sturgeoncaptured

Fig. 3ÉvolutionofAtlanticsturgeonlandingsintheSt.Lawrence ) 10-

20 - Landings (tons 100 120 140 160 20 40 60 80 0 40 5060708090100110 120130 by commercialfishing insectorsAandB,1994. 40 434649525558616467707376798285889194 estuary, 1940-1996. L n =1271 50%< 100cm Sector A Fork length(cm) 111111 Year I 1 n =893 13% <100cm Sector 140 150160170 I riEP B 50 40 1991 30 1986 n =223 20 1982 10 19H1 0 .1.11imihmom 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 50 1986 40 • 1992 30 n=272 20 1988

10 1982 %) 1111 ( 0 J- 6-- 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

ncy 50 1988 ue 40 1993 30 n = 386

freq 20 10 ive .1982 t 1986 la 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Re 50 40 30 20 10

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Age

Fig. 8 Distribution of age frequencies of Atlantic sturgeon captures carried out in the St.Lawrence estuary, 1991-1994. ANNEXE 2

communications by country comte a uthor(s) /ride session/09mm

Hochleilhner M., Gessner J. El Pester The sturgeons and paddlefishes (Acipenseriformes) of the world Meir biology and aquaculture with an annotated bibliography

• •:;.:k"ke

Caron F., Tremblay S. E3 oral Structure and management of an exploited population of Atlantic sturgeon (Acipenser oxyrhynchus) in the St. Lawrence Estuary, Quèbec, Canada. Hildebrand L., C. Mcleod, S. Mckenzie E3 vrai Statue and management of white sturgeon in the Columbia river in British Columbia Mcleod C., L. Hildebrand, D. Radford E3 oral Management of Lake sturgeon sport fisheries in Alberta Mcleod C., L. Hildebrand, S. Mckenzie E3 poster Fraser river white sturgeon monitoring program Seyler J. E3 Pester Habitat utilization by juvenile lake sturgeon (Acipenser fulvescens) in a northem clay ben river Francia G., G. Verreault E3 poster Atlantic sturgeon fishery management in the St-Laurent river, Canada

Chang Jlambo E3 oral Immersion marking of terrai Chinese sturgeon, Acipenser sinensis, with aErzarin Jiang L. E2 oral Effects of ecological environmental pollution on Chinese sturgeon (Acipenser sinensis) Sun Dajlang A2 poster Amur sturgeon (A. serencki) farming in China Yu J. E2 poster Effects «thermal pollution on the Chinese sturgeon (Acipenser sinensis) Zhuang Ping and Yi Jifang A2 oral Sturgeon and paddlefish aquaculture in China

r

Paaver T. El poster Distribution of native and introduced species of sturgeons In Estonie e:e. .,,,, ...... • ....::-,-e:•541. Billard R., J, Casson, O. Linhart and L.L Tsvetkova Al oral Motility analysis of fresh and thawed spermatozoa in Acipenser baeri. Brun R., R., E., Torre, M. and Elle, P. E3 oral Marking of sturgeon Acipenser sturio L. alevins destined for restocking Le Menn F., Pefissero-Benneteau C., Wiiiiot P. and Cuisset-Davall B. Al oral Female Siberian sturgeon Acipenser baeri: an interesting model for reproduction physioiogy studies in fish. Rochard Eric, Lepage M., Tremblay S. , Gazeau C. El poster Spatial distribution of juvenile sturgeons (Acipenser sturio 1_,) in the Gironde estuary beforetheir first joumey to the sea.

Pagina I di IO country author (s) /tille session/comm. Ghobad Azeri Takaml E3 poster Soma new data on artificiel propagation and source of broodstocks of beluga (Huso huso) in Iran. Kevyanfar A., Khanlpour A. E3 poster The remit of using trammel net in Iranien cassiel waters of Caspian sea to catch intact healthy productive specimens for artificiel culturing Kevyanfar A, Nasrichari A. El oral The reste of biometrical and biotechnical studies In Iranien coastal waters of Caspian sea on the independence of Acipenser persicus from Acipenser gueldenstaedti Mojabi, A., Sh. Safi, Gh. Azeri Takami, L Nowrouzian Al poster Comparative study of comparative study of classification index and hormonal measurement to determine the time of sexuel maturity in Acipenser persicus Nowruz Fashkhami M. R., Khoroshahl M. El poster 'Caryotype study on stellate and great sturgeon by leucocyte culture Pourkazeml M., Skiblreskl, D. O. F., Beardmore, J. A., El °rai application of mtdna d-loop region for the study of russian sturgeon population structure from iranien coastline of the caspian sea. Safi S., A. Mojabi, Gh. Azeri Takamf, 1. Nowrouzian, A. Skylab Al oral Evaluation of FSH, LH, progesterone, estradiol and testosterone to determine the most appropriate time for injection of pftuitary «tract in Acipenser persicus. Shafizade S. S., Parivar K. Al oral A study of the embryonic development of Persian sturgeon (Acipenser persicus Borodin) Taghavi Motlegh A. E2 poster Von Bertalanffy growth parameters oif the Beluga, stellate sturgeon, Persian sturgeon and Russian sturgeon living in the south part of the Caspian Sea

...... :. Agnisola C., Mckenzie D.J., Pence:ro, D., Bronzi, P.and Tota, B. E2 oral Heart function and cardioventilatory control under hypoxie in the Adriatic sturgeon (Acipenser naccarii) Ainerio M., Rage C. and Badint, C. A3 poster Performance of Acipenser baeri reared at two water temperatures Mati G, Poliakov, L, Hemando Casai J., Bronzi, P. and Giovannini J. A2 poster Preliminary data about growing up at different temperature in a farm plant of hybrid sturgeon "AL" (A. naccarii x A. baeri) Arlati,G, A. Grass, and A. Granata E3 Poster Restocking Lombardian Region rivers with the autochtonous Adriatic sturgeon (Acipenser naccarii) Badin G., Malorana G. and Montorio L A3 poster Growth of juveniles of Italian Sturgeon (Acipenser naccarii Bonaparte) reared in laboratory conditions. Barzaghl, C., Mc Kenzle, D., Boglione, C., Bronzi, P., Di Marco, P., Oint L., Cataldl, F. and Cataudell E2 poster Acclimation trials of embryos and lune of Acipenser naccarii to different Boglione C., Bronzi P., Cataldi E., Serra S., Dini L.. and Cataudella S. Al poster Early development of Italian sturgeon Acipenser naccarii : preliminary results Balla M., Sala A., Zarini S., Favaro L., Agradi E. A3 poster Cytochromes p450 - dependent metabolism of essentiel fatty acids in sturgeon Acipenser naccarii, Brevini T., A.L., Fiameni M. C., Rigamonti E., Agradi E. E2 oral Cytochromes p450 in sturgeon Acipenser naccarii. Bronzi, P., Aria", G., Rosenthal, H. and P. A2 oral Status and prospects of sturgeon farming in Western Europe Calait» E., Di Marco, P., Mckenzle, D., Mandich, A., Bronx', P. and S.Cataudella E2 poster Chemicai properties of Italian sturgeon Acipenser naccarli, blood: preliminary results Cataldl, E, Mc Kenzie, D. , Dl Marco, P., Mandich, A., Boglione, C., Brutal, P. and Cataudella, S. E2 oral Some aspects of osmotic and ionic regulation in Italian sturgeon, Acipenser naccarli.

Pagina 3 di 10 country author(s)/ titie session/comm.

Bacalbasa-Dobrovicl M, Patriche AL E2 °rai Environmental studies and recovery actions for sturgeon in the Iower Danube Cristea Y. , Oprea L*, Pecheanu C. and Patriche N. E2 poster Histological aspects of gonadal development stages on Acipenser stellatus Patriche N., Pecheanu C, Danut M A2 poster Contribution te the artificiel propagation and fry development in the first stages of Acipenser stellatus in mobile faceities on the Danube river banck. ge7,0ee,reeffl

Abramenko M. L A2 poster The obtaining of the sturgeon production in the conditions of cellulose-paper plant Abramenko AL Land Poltatseva T.G. A2 ore The first experience of artificiel reproduction and groWing of sterlet (A.r.) in the Northem Dvine region, Arkhangelsk region. Abrosimova N. A3 poster The importance of antibacterial preparations for intensive rearing of sturgeon fry Abroslmova N., Abrosimov S.S.and Blryukova A.A. A2 poster Effect of the lipid composition of stellate sturgeon eggs on commercial qualifies of this species Altufyev Yu. V., Romanov A.A., Druravleva G.F. and Seheveleva N.N. E2 oral Morphofunctional a bnormalities in some organe and tissues of the Caspian sturgeons (Acipenseridae) Anatsky S. Ju. El oral Present day statue of the Baltic sturgeon: the view tram Russia. Aregev V. El °ral Cytogenetics of interploid hybridization of sturgeons Artyukhin El oral On a taxonomie status of the Atlantic sturgeon within the geographical range Artyukhin N., LA. Barannikova and A.G. Romanov Al oral Main features of conservation and reproduction of sturgeons in Russia including the rare endangered species Barannikova L Al oral Sex sterads concentrations in blood serum of sturgeons and its specifio cytosol binding in braie on different stages of the migratory cycle. Barannikova LA., LV. Bayunova, V. P. Dyulen and T. B. Semenkova Al oral Interrenal function and serum cortisol levels in migratory cycle of sturgeons. Boiko MIL E2 poster Formation of olfactory imprinting and thyroici hormone metabolism in early ontogortesis of Russian sturgeon. Bugrov L.Y. A2 poster risuits on the experimental rearing of belouga in submerged cages in the caspian sea Burlakov A. Al poster Sex specifity of pituitary gonadotrepins in sturgeon Burlakov A., Aveyanova 0.V., Puschkar Golichenkov V.A. Al poster The effect of laser irradiation on earty development of sturgeons Burtsev I. A. A2 oral On the history of sturgeon introduction in world aquaculture Chebanov M., Savalyeva E.A. E3 oral Sturgeon culture in the Sea of Azov Basin: problems and prospects of new biotechnology Chebanov M., Savalyeva E.A, Tleouj M.G., Chertihin Melchenckov A2 oral An experiment on season's control of paddlefish propagation

Pagina 5 di 10 country atahor(s)/title session/comm. Loukianenko V., Vasirev A.S., Lukyanenko V.V., Khabarov M.V. E3 oral On the growing threat of the extermination of the Caspian population of sturgeon fish Metallov G., P.P. Geraskin, V. P. Aksenov E2 Poster Some aspects of sturgeon (Acipenseridae) hybrid physialogY• • Nevalyonny A., Korostelyov S.G. A3 oral Acipenser baeri polysubstrat, digestion "in vive an "in vitro". Aleyfakh A. Al oral Nucleo-cytoplasmic incompatibility of androgenetic hybrids in sturgeon fiches. Obukhav D. if. E2 Poster Cytoarchitectonics and neuronal organization of the sturgeon telencephalon Ozernyuk N.D., Klyachko 0.5 E2 poster Environmental bioenergetics and optimal temperature conditions of the sturgeon development. Palgul V. A. E3 oral Compensative growth ot sevruga (Acipenser stellatus I.) at the Caspian sea. Petruslikieva D.S., P. Khodorevskaya E3 Poster Distribution and qualitative structure of sturgeon (Acipenseridae) population of the coast of Kalmykia Podushka S.E. Al poster New method of obtaining eggs In sturgeons Polyanlnova A. A., Kashentseva L.N., Malinovskaya, L.V., Molodtsova A.L and Sm1rnova, L.V. E2 ore Feeding conditions for sturgeon (Acipenseridae) in the Caspian sea. Ponomariov S.V., Bakhareva A.A., Zagutkina LY. A3 Poster New formulated diet and rearing technology of sturgeon cultivated in Volga-Caspian region Ponomariov S.V.,Bakhareva A.A., Zagutkina Z.Y. A3 Poster New concept of combining formulated starter diet (feed) for sturgeon fry Popova A. A., Piskiinova L.V. and Damagala Yu. Al oral Histological analysis of gonade of beluga reared under artificiel conditions Rezanova G. M, E. Yu Tlkhonova A2 Poster Commercial sturgeon (Acipenseridae) culture in sea cages Romanov A.. A., Zhuravleva G.F. E2 Poster New pathological manifistation of gonad-gametogenesis in Caspian sturgeon (Acipenseridae) Rykova T. E3 Poster Sturgeon transplantation and acclimatization Saenko l.L El poster Spinal cord of Acipenserldae Semenkova T. B., L V. Bayunova, A. A. Boev, V. P. Dyubin A3 Poster Stress influence on serum cortisol levais in sturgeon aquaculture. Semenkova T. B., 1. V. Trenkler, R, 1. Kovalenko A3 Poster Influence of pineal peptides on restoration of moving activIty alter handling and asphyxia. Sergeeva N. A3 poster Dietary zinc, manganese and copper levels on zinc, manganese and copper concentrations in tissues of sturgeon Shelukhin G. K, Yu.V. Altuflev, A.A. Romanov. A.V. Rizvanova. E2 oral Specific features of Caspian sturgeon response to environmental anthropogenic pollution Shevchenko V. N., NI.A.Rogov , Irai Effatpana Komaei A2 poster Rearing technology for fingerlings of the Sefidrud Russian sturgeon (Acipenser gueldenstaedti B.) in the Islamic Repubhe of Iran Sokolsky A., Mednaya L., Mikoulza* A.S. A2 poster Acclimatization of paddle fish on the delta of river Volga (Polyodon spathula Waib.) Sokolskr A., Mikouiza A.S.,Stepanova T. A3 poster Nutrition of sturgeon reared in ponds on the delta river Volga Sudakova !k V., Ponomariov S.V. A3 Pester New types of mixed feed for sturgeon

Pagina 7 di IO country author(s)/lide session/comm. Sorlguer M. C., J. Domezain, A. Domezain , M. Bernai, C. Esteban, J.C. Fumer and J. A. Hernando A3 poster An approximation of the feeding habits of Acipenser naccarii (Bonaparte 1836) using an artificiel river

J Adkison M. A., C. Lee, N. Rooljakkers and R.P. Hedrick. E2 oral Investigations on the immunune response of the white sturgeon (Acipenser transmontanus) and applicability to immunrzation against white sturgeon herpesvirus-2 Birstein, V. J., P. Doukakis, and R. Desalle El oral tvlolecular phylogeny of Acipenserinee and black caviar species identification. Brach R. E3 oral Management of lake sturgeon on the Winnebago system - long term impacts of harvest and regulations on population structure Dabrowski K., S. Czesny, J. E. Christensen, J. P. Van Eenennaam, ami S. L Doroshov. A2 poster Fatty acid composition of sturgeon eggs - discrimination of domestic and wild one Doroshov S., J. P. Van Eenennaam and G. P. Moberg A2 oral Development of white sturgeon broodstock Duke S., P.anders, G.Ennis, B.Halloclç J.Hammond, J.Laufle, R.Lauzier, L.Lockard, B.Marotz, V.L.P E3 oral Recovery plan for Kootenai river white sturgeon (Acipenser transmontanus) Fltzpatrick, M.S., Feist, G.W., Foster, E.P. and Schreck, C.B. E2 oral Reproductive physiology of wild sturgeon (Acipenser transmontanus) from the Columbia river. Gawlicka` A., D. Gagnon, L. riait, a Hellen, K. D. Shearer, J. De La Noie and S.S.O. Hung A3 poster A new rnethod for digestibility measurement in white sturgeon juveniles George* T.A. and Daniel R. Brady El poster The teeth of the paddlefish, Potyodon spathula Linares-Casenave J., J. P. Van Eenennaam, S. L Doroshov Al poster Temperature-induced ovarien atresia in the white sturgeon, Acipenser transmontanus. Mojazi Anet B.,T. E. Adams, S. L Doroshov, G. P. Moberg Al oral Use of mammalien gonadotropin-releasing hormone to characterize pituitary gonadotropin releasing hormone receptors in white sturgeon (Acipenser transmontanus Richardson). Moreau R., Dabrowski K. A3 oral Vitamin C - vitamin E interaction in juvenile lake sturgeon (Acipenser fulvescens r.) St Pierre R. E3 oral Potentiel use of cultured Atlantic sturgeon for restoration or enhancement stocking Stevenson J. and D. Secor E3 poster Life history charaderistics of Hudson river Atlantic sturgeon (Acipenser oxyrinchus) and a model for management Sulak K. J.and J. P. Clugston E3 oral Early lite history and population structure of gulf sturgeon, Acipenser oxyrinchus Desotoi, in the Suwannee river, Floride Takata H. A. and Hopkins K. D. A2 poster Russia Sturgeon Culture Project in Hawaii Van Eenennaam A., J. P. Van Eenennaam, J. F. Medrano, S. 1. Doroshov Al oral Induction and gens dal sex of meiotic gynogenetic and polyploid white sturgeon (Acipenser transmontanus Richardson). Van Eenennaam A., J.D. Murray, J. F. Medrano El poster Synaptonemal complex analysis in spermatocytes of white sturgeon (Acipenser transmontanus Richardson). Van Eenennaam J., S. 1. Doroshov Al poster Age and body size of Hudson estuary Atlantic sturgeon (Acipenser oxyrinchus) at different stages of gametogenesis

reillie 4 di 10 ANNEXE 3 El -O 3^i ISS 97 SENT DAY STATUSF`THE::BALTiC STIJ.FtqgQ. . • ...... •

Sergey Anatsky::: Department of Ichthyology and Hydrobiology, Saint Petersburg University, 16th Line 29, Saint Petersburg, 199178, RUSSIA

Abstract. The Atlantic (Baltic, common, European, German) sturgeon (Acipenser sturio L.) is doubtlessly one of the most rare and valuable inhabitant of the Baltic sea. This sturgeon is included in the New York Convention for Species (IUCN), in the Washington. Convention for Species Protection (CITES) and in the addendum of the priory-list of protected species of special interest to the European Union. Previously it has been endemic for ail major river in Europe as well as in the adjacent coasta! regions (Berg, 1948; Mohr, 1952). Due to overfishing, hydre- development and pollution of the rivers the common sturgeon is almost extinct today. The small native stocks have been proven ta persist in the rivers Rioni (Ninua and Tsepkin, 1984) and Gironde only (CEMAGREF, 1987). The population of the sturgeon in the North Sea is considered to be "not self sustaining" and in the Baltic is classified as "missing" since the turn of the century. Occasional catches of the common sturgeon are stil! recorded -in the Elbe River estuary in Germany as weli as in the Gulf of Finland and the Ladoga lake in Russia (Debus, 1995, Kuderskij, 1983). The information on fishing up of separate specimens from Ladoga lake in basic, where, probably, lives a local population of this species, not migrating into the Baltic sea. However, the information on sturgeon biology is practically away in these regions. Therefore a main aim of the work is ta review the literary and archiva! data on the biology of the A. sturio in the east part of the Baltic sea and in the Ladoga lake. On the basis of the analysis of received results are discussed a complex of problems, connected to the establishment of the taxonomical status of caught individuals. The conclusion is made, that A. sturio was much kept in the Baltic sea as a biological species. It is obvious, that for the save of A. sturio it is necessary ta accept a complex of special measures, creation of international system of detection, fishing, restoration of stock and special study of Baltic sturgeon. The list of the publications on Acipenseridae in east part of the Baltic sea is resulted in the work for the first time.

Referen ces

Berg L.S. 1948. Ryby presnych vod SSSR i sopredel'nych stran. V.1., AN SSSR-Publ., Moscow- Leningrad, 466 p. (in Russian). CEMAGREF 1987. L'Esturgeon doit pas disparait. Division Amenenagement Littoraux et Aquaculture (ALA) du CEMAGREF en collaboration avec I'AGEDRA, 21 p. Debus, L.(1995) Historic and recent distribution of Acipenser sturio in the North and Baltic Seas. Proc. lntern. Sturg. Symp., VNIRO-Publ.: 189-204. Kuderskij L.A. 1983. Osetrovye ryby v basseinach Onezhskogo i Ladozhskogo ozer. In: Sbornik Nauchnych Trudov GosNIORCH V. 205: 128-149. (in Russian). E3 -P /55 '97

AUTOCHTONOUS ADRIATIC STURGEO

riati, A. Grassir rail Dip. Regione Lombardie, Centro di Ricerca ldrobiologica Applicata alla Pesca, P.zza IV Novembre, 5 Milano - Italy

INTRODUCTION ln Italy Acipenser naccarii species is faced with a danger of extinction with and also in Lombardy region it was almost completely extinct consequently to environmental problem and Human modifying of migration areas and spawning grounds(1). In the year 1977 a lombard fish farmer started storing and rearing in an apposite farm pond a certain number of wild sturgeons, hoping a future management of this seed as availabie brood stock for controlled production cycles.

RESTOCKING PROJECT The first attempt of handly spawning was tried in 1985 but only from 1988 (2), by induced breeding bloodless mature sturgeons treatment method, was possible te manage fertilized eggs. The fertilized eggs had been hatched and the juvéniles (3) then utilized in the first experience of restocking vocational river waters. Successfully controlled reproduction allowed the beginning of a pertaining to the geographic distribution of Acipenser naccarii sperimental project. This project presupposed preliminar studies on: • brood stock aboriginality, these studies has been actuated with the contribution of Russian geneticists (4); • historical rivers vocational growth places and spawning grounds; • appropriate fishes size to intake in the identified vocational river places.

The first phase of the restocking projet has intaken in the major Lombardian rivers sturgeons of different size, from 2,5 cm (0+) ta 80 cm (3+), in a total number of 37.000 in the period from 1988 ta 1996 (tab 1).

CONCLUSION Research is directed te: • reintroduction of Acipenser naccarii in vocational waters to avoid a complete extinction of this species; • increase scientific knowledge about sturgeon population ecology and biology, and mainly to indagate about reproductive period, migration areas, growth rates and sexuel maturity, so that in the future some fishes will be selected as biomarkers and followed in their migration and grouth phases. EI - 3-, 155 :97 ON .A TAXONOMIC STATUS OF THE ATI_ C STURGEON THE G EOGRAPHICAL RANG

N. Central Laboratory on Fish Reproduction, 199022, S.-Petersburg, Prof. Popova St. 24/52, Russia

Summary. Evidently ail the local populations of Atlantic sturgeon both in Europe and in North America are the single species. There were discovered in the Collection of Zoological Institute of Russian Academy of Science 4 specimens of Atlantic sturgeon Acipenser sturio from the Ladoga Lake with a central membranous fontanelle between frontal and parietal bones on the scull roof. This is one of the important characters that distinguishes American A. oxyrhynchus from European A. sturio (Magnin, 1964). This fact induced me to the analysis of other morphological characters, which were used by Magnin in his comparison of American Atlantic sturgeons from the St. Lawrence River and European ones from the Gironde River. It was found out that A. sturio of the Ladoga Lake (a part of Baltic sea population) as well as_A. oxyrhynchus from Canadien watersheds possesses a fontanelle in scull roof, an elongated form of scutes, a radial-alveolar sculpture of scutes' surface and rhombic plates of the skin, a similar body proportion, a pale colour of peritoneum and, finaily, the same number of dorsal and lateral soutes. In Magnin's sense the Baltic A. sturio could be distinguished from A. sturio of the Gironde river as the valid species. But it is a nonsense. Moreover, morphologically close populations of A.sturio from the Gironde river, the Mediterranean Sea, and the Black Sea demonstrate some similarity with southern American population A.o.desotoi by squarish dorsal soutes with a tubercular-radial surface. Because of difficulty of suggestion that A. o. oxyrhynchus originated directiy from the Baltic A. sturio or vice versa, I dere say both European and American Atlantic sturgeons represent a single species. Evidently, it is possible to determine four subspecies, namely: A.s.sturio (Baltic sea basin), A.s.occidentalis (Atlantic ocean, Mediterranean and Black seas), A.s.oxyrhchus (Atlantic coasts from Labrador to Florida), and A.s.desotoi (Gulf of Mexico). Ail the infraspecific differences of body proportions in Atlantic sturgeon are on the similar level as in Russian and Siberian ones within their geographical ranges.

Reference

E. Magnin, 1964 Validate d'une distinction spécifique entre les deux Acipenséridés: Acipenser sturio L. d'Europe et Acipenser oxyrthynchus d'Amerique du Nord. Le Naturaliste Canadies, Vol. XCI, Ni, p.5-20 E2 - 0 3' ISS '97 ENVIRON M FNTAL--$TUMESANDIftEÇOV ....$1711RGEON:leTHE...MitifeWPANLI

Bacalbasa,- Dobrovici Patrie *nDunarea de Jas" University, No. 47 Domneasca Street, Ro 6200, Galati, Romania

Sumrnary. Owing to media! changes and over-fishing, the Lower Danube sturgeon populations decreased drastically. The measures taken were limited to irregular restocking with a small number of fry and fingerlings. There was observed changes of the trophic faune and of the repartition of the young sturgeon in zone. To increase the recovery actions of the sturgeon populations it is necessary a complex ecological study and an effective agreement of the riparian countries. Abstract A hundred years ago in the Low Danube were fished about 1000 t sturgeons early. Low Danube represent the river between the Iron Gates and the Black Sea. Alter the construction of the "Iron Gates II" dam, only 862,5 km remained accessible for ail anadromons fishes. The Low Danube pass trough five countries: Yugoslavia, Romania, Bulgaria, Moldova and Ukraine. From the six species of sturgeons often mentioned in literature, only four are still captured: Huso huso, Acioenser gueldenstaedti, Acipenser stellatus and Acioenser ruthenus. During 1895-1933 the Lower Danube sturgeon were seriously studied by Grigore Antipa (1933) and by others later. The drastically decrease of the sturgeon catch in the last decade, when in the whole Lower Danube are caught only some tens of sturgeons tons - in Romania owing to the actually fishery organization there isn't a real and complete statistic had imposed the publication of some papers which succeed to pay attention on the danger of the sturgeon disappearance (Bacalbasa - Dobrovici, 1989; 1991a; 1991b). There are many causes of the sturgeon decrease; especially the limitation of the spawning areas, as a consequence of the "Iran Gate I and II" dams construction, the river water pollution increase - mostly punctiform - great quantifies of heavy metals in bottom sediments and over-fishing. Initially, in Romania it was paid attention for the artificial spawning of sturgeon at Gura - Girlutei - Braila, Gura - Saltavei - Hirsova and the Litcov hatchery in the Danube Delta (Manea, 1980). Beginning with 1991 the Fisheries Research Center of Galayi start the artificially spawning of Acipenser stellatus and then of Acipenser gueldenstaedti and from 1996 of Huso huso. Atter the "Iron Gate" dams construction, the RENEL administration financed the Cetate - Dolj hatchery building, for sturgeon Danube restocking reason. The mentioned hatcheries restocked small quantities of fries and fingerlings in the Danube. The Yugoslavian hydroelectric organization from the "Iron Gates" contributed to the building of the Kladovo hatchery and finance it yearly for the restocking of the Danube. The environmental conditions in the Lower Danube are in continuous change. During over 55 years of work on the Lower Danube, we had the opportunity to constate the disappearance and appearance of Danube isles with great hydrological modifications (for instance Palingenia sp. disappeared as a consequence of water pollution). In a typical area for sturgeon tries and fingerlings (St. George branch) these are not more found, but in change it is present in the main Danube, Borcea arm and in the Chilia Delta branches.

E3 - 0 3,d15.9 '97 MAIleeEmEgr'OFLAKETPRQEON.0 QTgrirvI.:tmpAmCiftiARy: IgLAR EPOPULATION eTv

Wisconsin Department of Naturel Resources, P.O. Box 2565, Oshkosh, Wisconsin, U.S.A., 54903

Abstract. Lake Winnebago, a 56,130 ha shallow glacial Lake in East Central Wisconsin, U.S.A., is home to one of the largest self sustaining lake sturgeon, Acipenser fulvescens, populations in North America. The State of Wisconsin bas been attempting to manage the size and harvest of this sturgeon population since an initial harvest ban from 1915-1931, and has been collecting population assessment data since the late 1940's. Winter spearing, the traditional harvest method, accounts for 38,770 harvested sturgeon since mandatory harvest registration began in 1955. Sirice the mid 1950's, efforts to maintain annual exploitation at 5% or less resulted in reductions of individual season bag limits from 5 to 1, and increases minimum size limit from 76 cm te 102 cm, and then to 114 cm. Alter an initial decline, harvest rates eventually increased as spearing effort increased three fold over the last two decades. While historie population assessment data has shown an steady increase in the overall numbers of lake sturgeon in the Winnebago population since the late 1950's, a trend emerged since the mid 1970's which showed a decrease in the numbers of the largest fish in the stock (Figure 1). Annual harvest and population assessment efforts were expanded in 1991 to examine the trend, document the current and potential long terni impact of the apparent increased exploitation of the largest sturgeon in the population, and recommend any changes necessary to maintain acceptable exploitation levels and desired population size and age structure.

Historie harvest and population assessment data was standardized to current data management formats where possible, and re-examined for discernable effects of past regulations and/or harvests. Annual harvest assessment, which, since 1955 %rubor of Marron Hartootod %efFile $11 NO hi Noms! included the total number of fish harvested 4000 and total length and weight of individual 1000 fish, was expanded in 1991 to include sex 2000 and stage of maturity, and age of individual 2000 fish. Annual assessment of the spawning 1000 stock, which since 1975 included total 1000 length and sex of fish captured at 000 spawning sites was expanded to include age of spawning fish. Techniques used 1141 1040 rosi *00 *11 *71 *70 1001 1010 1011 000 historically to measure densities of the YEAR V141-$14 Msnwt Mai sn •étheldell. Me 'Minet,» uwallelila L.Weinaliage legal sized stock were refined ta allow 1041.411.1 IlaMatmorr reg. Hf» le me. estimation of the number of males and Figure 1. Winnebago System Lake Sturgeon females in the spawning stock. From Harvest, Winter Spear Fishery, 1941-1996. 1991-1996, 8,099 lake sturgeon were registered in the harvest, of which 3,723 were examined for sex and maturity, and 2,568 were examined for age. 4,054 sturgeon were captured at spawning sites from 1991-96. All spawning fish captured were tagged and a subsample of 1,130 fish were sampled for age. E3 - 3,, 155 '97 RKING OF STURGEON Acipenser sturto S DESTIN FOR RESTOCKING

Brun .flochard.E4Ttérrel,14.Elie• *cemagref: French lnstitute of agricuitural and environmental engeneering research, 50 avenue de Verdun, BP 3, 33612 CESTAS cedex, France

The European sturgeon, A sturio, is an endangered species and fishing has been forbidden in France since 1982. To accelerate the restoration process, restocking operations have been implemented using hatchery produced alevins. The alevins are released into Gironde -Garonne Dordogne rivers, and the estuary system, the only river basin in which the species stil) performs its reproductive migration. Before their release into the natural environment, it seemed an .interesting proposition to mark the individuals in order later ta be able to : • differentiate the fraction of the population resulting from in situ reproduction compared ta that composed of hatchery-bred individuals. • determine in the future the efficacy of alevin releases in population restoration • increase knowledge on the growth of species in the natural environment.

The method used involves tissue marking, which makes it possible to study the biology of the fish. Various fluorochromes, including tetracyclins, were used. Initial results have already demonstrated the effectiveness of the markers, administered intraperitoneally, and their innocuousness at the recommended doses. However, the procedures and time required by this technique do not justify its use in treating large numbers of fish, which is the case in alevin releases. After testing these products on A. ruthenus in short periods of baineation, we marked A. sturio fingerlings of 1g to 6g. With this technique, it was possible to observe the good state of impregnation of the ossified parts (the first spine of the pectoral fin, for exarnple). Using a thin slice of this spine (after inclusion and polishing), the presence of the marker was determined under UV light by the fluorescence emitted. A check on A. sturio 14 months alter marking showed perfect impregnation located in the central part of the spine. This observation has been verified on individuals kept at our research centre and for those caught in the natural environment after the initial release of marked alevins during 1995. A.2 - 0 /5.5 '97 THE HISTORY OF STURGEON INTRODUCTI AQUACULTUR

ev (VN1RO, Moscow)

Intensive development of aquaculture being the specific and important element of anthropogenic activity is accompanied with sufficient enlargement of not only production volume but also of number of cultivated species of hydrobionts. Introduction of each species or related taxa in culture has own history- which in a case of sturgeons is complex and quite long, started about 130 years ago. Stocks of sturgeons widely distributed in the Northern Hemisphaere from the middle of XIX centure began to decrease sufficiently due to fishing intensification and increase of water pollution. For that Ume there was successful experience on salmon and other teleost cultivation, so in the second half of XIX sturgeon had become a subject of artificial reproduction in Russia, USA and Germany simultaneously. The first experiment on sterlet (Acipenser ruthenus) egg insemination was made by Acad. F.Ovsjannikov in the Volga River: in collaboration with Drs. A.Kovalevskij and N.Vagner he investigated incubation and development of artificially fertilized eggs. Then other ichthyologists and fish farmers protonged such works: J.Knoch (who transported sterlet larvae in Scotiand in 1870), E.Pelcam, 0.Grimm, V.Zelenskij, N.Borodin, A.irashin and others. In USA artificial rearing of lake sturgeon (Acipenser fulveicens) was initiated by Dr. S.Green, and in Germany such experiments were begun by Drs. Frauen and Mohr with Atlantic sturgeon (Acipenser stuno). Practically from the beginning of such experiments Russian scientists not only reared larvae which were reieased into natural habitats but also investigated growth and development for some months of age. On the first Russian fish hatchery, Nicolskij hatchery, sterlet fingerlings were grown to rather large size in ponds: it characterized by rapid growth and high food efficiency, but considered to have no possibility to mature (Grimm, 1905). So, those data had put the basis not only for artificial reproduction of sturgeon but also their fattening for market size. Sturgeons abundance in the Caspian and Azov basins was always sufficiently higher than in the Western Europe water drainages, so in former water bodies fishing pressure never reach critical point. At 20s in the XX century such situation was in Western Europe. Another problem takes place in USA where the absence of interest to cultivate sturgeons results from low popularity of this fish: in particular, 100 years ago sturgeons meat had very low valuability and caviar was (H) thrown out (Borodin, 1890). On the contrary, in Russia sturgeon price was in 5-6 Limes higher than salmon price and caviar was aiways the actual delicacy. So, it is understandable why interest in sturgeon cultivations was stable in Russia in spite of a series wars and revolutiona shocks. There is a gallery of well-known Russian researches who have become real clssicists and made the basis of biotechnology of artificial sturgeon reproduction and rearing: A.Derzhavin, N.Gerbilskij, N.Kozhin, V.Milshtein, T.Detlaf, A.Ginsburg and many others. In spite of the wide creation of hydropower stations and dams the natural stocks of such species as Russian sturgeon (Acipenser gueldenstaedth), great sturgeon (Huso huso), sevrjuga (Acipenser stellatus) and skip (Acipenser nudiventris) had been conserved due to building of large series of fish sturgeon hatcheries. E3 - 0 /55 '97 TRUCTURE AND MANAGEMENT OF I E KPLOITED`'PO OFATLANTIC STURGEON (A cipenser onr inc STIAWRENCE ESTUARY, QUESEj

:FÉancojeCatoealnelSargeTrernbla. Ministere de l'Environnement et de la Faune, 150, Boul. René-Levesque Est (5) QUÉBEC (QC), CANADA G1R 4Y1

Abstract. The Atlantic sturgeon, Acipenser oxyrhinchus, has been exploited commercially in the St.Lawrence estuary until today but the fishery has never been enough controlled. In -tact, during recent years, landings have increased of more than 50% ( 120 t in 1993) and the median age has gone down from 11 to 6 years. Since 1994, we adopted initiatives to reduce the landings at 60 tons per year for 1998. So, we have conducted studies to improve our knowledge of the fishery in the two main fishing sectors with the fishermen collaboration, and to measure the effects of some new regulations such as gillnet restrictions, fishing effort control, closed season and size Iimits. We have also evaivated recruitment and structure of that population. The exploited population is only composed by juveniles (FL: 50-170 cm). The adults are totally absent from the catches. The location of spawning grounds are unknown. The Iast strong cohort is bom in 1988. The fishing success fiuctuated between sectors, weeks and fishermen. It is clear that upstream sector was the most productive one with more than 80% of the landings recorded for aIl the fishery. The fishes showed some seasonal migrations between the two fishing sectors. That behavior increased their gillnetting vulnerability. Tag returns by a few commercial fishermen suggest a poor survival rate. Despite strong controlled regulations and a decreased in poaching activities, the landings have decreased after three years but not enough to reach our management objective. The Atlantic sturgeon St.Lawrence population is characterized by a variable recruitment, an high harvest ratio and a very poor knowledge of its key habitats. For the future, a great attention must be put on that population. A2 - O 3. /SS '97 Fl.eel4QPIVIZNT: Of yvergSTVRO OD

,k5E{::±•±.:5 erge I. Doroshov, :J et P Van Eenennaarti , Department of Animal Science, University of California, Davis, CA 95616-8521. U.S.A.

Abstract. The domestic broodstock is a life-line to commercial culture of sturgeons. II should fully support the production of fingerlings for growout and genetic improvement in the performance of cultured fish. Lote sexual maturity, longevity of the reproductive cycle, and complicated hatchery breeding of sturgeon makes broodstock development a difficult task. We will outline our collaborative work with the aquaculture industry on the development of broodstock of white sturgeon (Acipenser transmontanus), a large anadromous species of the Pacific Coast of North America. The culture of this fish began in California during the early 1980's, with establishing hatchery technology for propagation of wild sturgeon (Conte et al., 1988). As the production system was developing and sturgeon culture was expanding to other states, the major efforts were made to develop viable commercial broodstocks. Broodstock development program. Since development of native sturgeon broodstock faces complex biological problems and the initial utilization of depleted natural stocks, the collaborative approach is important. White sturgeon broodstock development programs in California and Idaho were initiated as the concortia of the aquaculture industry and universities or colleges, in collaboration with state government agencies. The wild broodfish have been collected for spawning in the Sacramento, San Joaquin, Columbia, and Snake Rivers over a period of several years. Such diverse geographic origin of the broodstock population founders is expected to provide for genetic diversity and effective breeding program. Currently, the first generation of white sturgeon broodstocks is maintained at 7 different locations, and the second generation is raised on California farms. All seedstock supply for sturgéon farming in California is supported by the domestic broodfish. They range 3-14 years in age and 10-100 kg in body weight, are raised in the freshwater intensive system (flow- through or water recycling) and fed commercial broodstock diets. Reproductive physiology and sexual maturation. Previous fragmentary knowledge of the reproductive physiology of Acipenseriformes is beginning to shape in the recent studies with the broodstocks of several species undergoing domestication, including white sturgeon, Siberian sturgeon, a hybrid "bester", and northamerican paddlefish. The gametogenesis and the endocrine régulation of reproduction in the white sturgeon broodstock were recently reviewed by Moberg et al. (1995) and Doroshov et al. (in press). While significant progress has been achieved, the physiological mechanisms of sex differentiation, onset of puberty in female, and final ovarian maturation remain inadequately investigated. As it could be expected from the lite history and optimal reproductive strategies of wild Acipenseriformes, the cultured white sturgeon is characterized by the prolonged juvenile stage, delayed sexual maturation of the females, and the labile, body size dependent, pubertal age. In a warmwater growout system employed in California, the differentiation of gonadal sex in white sturgeon occurs at age 20-22 months, first sexual maturation of male at modal age 4 years, and that of females at modal age 8 years. However, the individual females reach their first sexual maturity at a highly variable age (6-12 years), and the ovarian maturation rates within an age group are dependent on growth and body size. Alter the first spawning, E3 - 15.9 '97 COVERY PLAN FOR KOOTENAI RIVER WHIT (Acipenser transmontanus etè*Dtike'Patit Abders;. Lauzier, Larry tockard, Brian Marotz, Vaughn araganuan In ° Dept. of Fisheries and Oceans , Canada.

Abstract. The white sturgeon (Acipenser transmontanusl of the Kootenai River was listed as endangered on September 6, 1994 by the United States Fish and Wildlife Service. This transboundary population, residing in Kootenay Lake and Kootenay River in Canada, and the Kootenai River in the U.S.A., has been in general decline since the mid-1960's. There has very little recruitment to this population in the past 20 years. This population become isolated from other white sturgeon populations of the Columbia River basin during the last ice age of approximately 10,000 years aga. The population adapted to the pre-development conditions of the Kootenai system, with a high spring freshet and extensive ride channel and low-lying delta marshlands. Modification of the Kootenai River by human activities, such as industrial developments, floodplain diking, and dam construction has changed the hydrograph of the Kootenai River, altering sturgeon spawning, incubation and rearing habitats and reducing overall biological productivity. A Kootenai River white sturgeon draft recovery plan was prepared by the U.S. Fish and Wildlife Service in cooperation with the U.S. Army Corps of Engineers, Bonneville Power Administration, Idaho Dept. of Fish and Game, Kootenai Tribe of Idaho, Montana Dept. of Fish, Wildlife and Parks, and from Canada; the British Columbia Ministry of Environment, Lands and Parks, and the federal Government of Canada Dept of Fisheries and Oceans. The plan was peer reviewed and there was a parallel public consultation process, where public commentary was invited from bath sides of the international border. The identified short-term recovery objectives of the recovery plan are to prevent extinction and re-establish successful natural recruitment. The identified long-term objectives are the re-establishment of a self sustaining population and the restoration of productive habitat, in order to downlist to threatened status and subsequently delist this population when recovery is well established. Three specific recovery criteria for downlisting have been identified. However, specific delisting recovery criteria have not yet been compieted, and will be developed as new population status, life history, biological productivity and flow augmentation monitoring information is coilected. Ten specific actions needed for recovery have been identified and are discussed. These actions include spring flow augmentation during the reproduction period; a conservation aquaculture program to prevent near-term extinction; habitat restoration, and research and monitoring programs to evaluate recovery progress. Estimated costs of recovery are provided in the draft plan over ten years. Other physical and economic impacts of implementing many of the proposed recovery actions are also discussed. These include environmental benefits and costs not normally considered in benefit/cost analysis. E/ - 0 3^, ISS '97

Ontana Department of Biology, University of Ferrara , Via L. Borsari 46 - 44100 Ferrara,

Summary. Nucleolar organizer regions (NORs), constitutive heterochromatin and DNA base composition were detected in sturgeon chromosomes respectively with AgNO3, C- and fluorescent banding techniques. The NORs and telomeric sequences were identified by in situ hybridization. Abstract. Reports on banding of fish chromosomes are very few. In sturgeons, the difficulty to obtain good banding is furtherly increased by the high chromosome number and by the presence of numerous microchromosomes (Fontana 1994; Birstein et al. 1997). We evaluated the role of cytogenetic techniques (such as Ag-staining, C- banding, fluorescent staining and in situ hybridization) ta increase knowledge of sturgeon chromosomes structure and karyotype evolution. Cell culturing, preparation of metaphase chromosomes spreads and differential staining (C-banding, Ag-NOR staining; fluorescent banding techniques) were performed according to previously described techniques (Fontana et al 1996). For in situ hybridization a plasmid bearing a 1.5 kb fragment of rDNA containing part of the bovine 28S gene was completely biotin-Iabeled by nick translation. After hybridization, FITC-conjugate avidin was employed to detect the hybridization signal. A biotinylated oligonucleotide (TTAGGG)n probe was used to localize telomeric DNA sequences Nucleolar organizer regions Silver deposits (Ag-NORs) in A. ruthenus (2n = 118±4) and H. huso (2n 118±4) were iocated at the terminal end of two chromosome pairs, one made up of small metacentrics and the other one of submetacentrics. The NOR number was 8 in the tetraploid species A. naccarii (2n = 246±8), A. baeri (2n = 248±8) and A. transmontanus (2n = 248±8). The nucleolar organizing chromosomes can be arranged in two quadruplets of four chromosomes each, again made of small metacentrics and acrocentrics. A. gueldenstaedti (2n = 258±8) exhibits a larger number of NORs which can anyway be grouped in quadruplets with the exception of a large unpaired metacentric. In this species, the simultaneous presence of NORs in ail the telomeric regions of four metacentrics indicates translocation réarrangements of the original rDNA sites. The possibility to group NOR chromosomes in pairs in species with about 120 chromosomes and in quadruplets in species with 240 or more represents a sound support of the diploid-tetraploid condition of Acipenseridae. Localizations of rRNA genes detected by in situ hybridization using a biotin-labelled probe supported the NOR position shown by silver staining. However, in the diploid species (such as A. ruthenus) the hybridization signais appeared clustered while in the tetraploid ones (such as A. naccarii) they were scattered along chromosomes. Constitutive heterochromatin The chromosomes of two tetraploid species, A. naccarii and A. gueldenstaedti and of the diploid H.huso were studied by C-banding. Heterochromatin blocks were clearly detected in the centromeric regions of the acrocentric chromosomes, notwithstanding their extremely small size. The biarmed chromosomes, especially those of medium or large size, exhibit a weak or absent C- positive centromeric region. Such a result could be explained by the ancient engin of metacentric chromosomes by Robertsonian fusion of unarmed ones. PA - 0 3- 1SS '97 UROPEAN-WIDE COORDINATION TRIAL FOR PROGRAMMES AVE THE COMMON STURGEON Act mer s

.essaer Hiebialth.nare:Aader-S, *Society to Save the Sturgeon e.V., An der agerbe 2, D-18069 Rostock/Germany

Abstract. On July 1 e, 1994 the "Society ta Save the Sturgeon" has been founded at the reknowned Senckenberg Institute in Frankfurt/Main. Initially this activity was started in Germany where the need to unite the interested groups became apparent at that time. From this nucleus the Society has invited organizations or persans working in this field to become members and to actively participate in the planning and execution of programmes. Meanwhile the Society has members in 10 European countries. The Common Sturgeon (Acipenser sturio Linnaeus, 1758) is the only sturgeon species with a distribution all over Europe. Previously it has been endemic ta all major river systems in Europe as well as in the adjacent coastal regions. Due to overfishing, hydro- construction, gravel extraction and pollution of the rivers, the Common sturgeon is almost extinct today. Only in the rivers Rioni and Gironde, small stocks have been proven to persist. Acipenser sturio is included in the New York Convention for Speciés protection (IUCN) as well as in the Convention on International Trade in Endangered Species of wild fauna and flore (CITES) and in the addendum of the priority-list of protected species of special interest to the EU. The Society aims at the salvation and the protection of the very last specimen and thus the last available genetic resources of Acipenser sturio world-wide. The Common sturgeon represents the loss of environmental quality and viability in a very typical manner, not only because it is the biggest freshwater fish in its distribution range but due ta the fact that the decline has been influenced by man in a typical way. An example of the decline of sturgeon stocks by the influence of fisheries is given in Fig.1. The drastic decline of the stocks during the last 10 decades requires immediate intensive endeavour for its protection due to the fact that we have only very few specimen available to reach this aim. Essential prerequisites for the protection and re- establishment of the Common sturgeon stocks will be the unification of the remaining species allover Europe and their artificial propagation. Thereby building up a broodstock that will forrn the nucleus of a self sustaining population. The spawners are and will be a very limited resource thereby making the effective and responsible utilization of this source rtecessary. This can only be realized in an international cooperational partnership of ail countries involved. Considering that the Common sturgeon require very long time to reach sexual maturity under natural conditions, the aim of this project can only be reached by Iong-term planning and the persistence of activity for this time. In order ta secure the required activity, i.e. building up the broodstock, production of fingerlings, ecological assessment etc. this task can hardly be undertaken by one country alone. Therefore, the Society is about to provide and enhance a collaboration of international partners involved in this matter. It will locus on the international co-ordination of the activities in an European programme. The Society is supported by an independent E3 - 0 3-, /55 '97 TATteAremANAGEmENTofleirrEisrffl.g

.: .biaiii11.-i1- .etittie$IVIeLe-çi&tÏj;f$:C4e M e‘e0- R. L. & L. Environmental Services Ltd., 2nd Floor, 1410 Columbia Avenue, Castlegar, British Columbia, Canada, VIN 3K3

BACKGROUND Investigations of white sturgeon (Acipenser transmontanus) in the lower Columbia River in British Columbia, Canada have been conducted annually since 1990. The studies have focussed on obtaining information to describe movement patterns, population dynamics, reproductive biology, and habitat selection of white sturgeon in the free flowing section of the Columbia River between the Hugh L. Keenleyside Dam (HLK) and the Canada-United States Boundary. The Columbia River in both Canada and the United States has been substantially altered by dam construction, reservoir formation, and river regulation for hydro-power generation and flood control. Dams have restricted or blocked white sturgeon movements, segregated populations, and changed the natural hydraulic, water temperature, and water quality regimes. Reservoir formation has flooded critical- spawning habitats, reduced habitat diversity, and decreased naturel rates of nutrient and sediment transport. Reductions in water quality due to pollution from municipal and industrial inputs also may contribute te observed reductions in white sturgeon health, reproduction, and survival.

POPULATION CHARACTERISTICS The size and age-class composition of the white sturgeon population in the Columbia River below HLK has shifted from a population dominated by small fish (< 1.0 m total length (TL)) in the early 1980s to the present population comprised primarily of large fish (>1.5 m TL). This shift was attributed to problems with recruitment associated with Iow survival rates of early life stages although the exact reasons for the Iow survival are poorly understood. Suspected causes include higher predation rates due to increased water clarity and changes in fish species composition (i.e., increased number of coarsefish and introduction of piscivorous exotics) that have occurred since regulation of the river. High total dissolved gas levels, industrial contaminants, habitat limitations, and food availability may also be contributing factors. The estimated 1200-1400 white sturgeon that reside in the Columbia River in Canada below HLK exhibit a localized distribution. These fish concentrate in areas typically in excess of 18 ni depth that are associated with confluence areas of major tributaries, dam tailwaters, or deep mainstem pools. White sturgeon exhibit lengthy residence times in these areas and movements are generally restricted to within and between major holding areas. Population dynamics parameters are within the range reported for more southerly Columbia River populations. Spawning occurs at only one of several potentially suitable spawning sites available within the study area. This spawning area is located at the Columbia-Pend d'Oreille rivers confluence, where successful spawning has been documented annually since 1993. Back calculations based on early egg development stages, indicate between three ta fine spawning events have occurred annually. The number of recorded annual spawning events was substantially E3 - 0 ISS 97 NTEmp.pRARy STATU.S.of 7.HE. cAs Fo eipeoeettee:AND THE.:p:FplEttgrviipf.:TilEIRÇQNS

vanciv:i:A.D.Vtasertko, FLP.Khodorevskayal .1eL po p Caspian Fisheries Research Institute, 1, Savushkina st., As trakhan, 414056, Russia Over the last two decades sharp changes in the environmental situation and socle- economic position of the Caspian basin states have occurred which affected the sturgeon status in their major habitat. The sturgeon (Acipenseridae) stock in the Caspian Sea is formed by natural and artificial hatchery reproduction. Their number is not stable. The largest catches of sturgeons in the Caspian basin were recorded at the beginning of the current century (39,400t) and in the mid 1970s (27,400t). The Volga-Caspian region is of primary importance for sturgeon restocking. 75.7% of the sturgeon catch originales from this region, 19.3% is from the Ural- Caspian region, 5.0%, is from the Kura and Terek rivers. The Volga Russian sturgeon (Acipenser guldenstadti B.) accounts for 98.7% of the population feeding in the sea. The Volga beluga sturgeon (Huso huso L.) living in the Caspian Sea amounts to 55.0%. Long-term studies performed by KaspNlRKh show that sturgeons are preseritly in the critical state. From the resuits of the 1983 trawl surveys 46.6 million specimens of the Russian sturgeon, 53. 1 million specimens of the sevruga (Acipenser stellatus P.) and 15.0 million specimens of the beluga sturgeon (ignoring one-summer old fish) fed in the sea while in 1994 only 21.2 million pcs. of the Russian sturgeon, 13.6 million specimens of sevruga and 8.9 million pcs. of the beluga did. Over the last 30 years there have been some changes in the species composition due to some environmental impact. The portion of the Russian sturgeon decreased from 70.6% in 1962 to 66.2% in 1995, of the sevruga from 29.1%, te 26.8% whereas the pro- portion of the beluga sturgeon has increased from 0.3% to 7.0%. The increased number of the beluga sturgeon is a result of its rearing on fish-farms as the rate of natural reproduction of the beluga sturgeon is very low. The decline in the total and commercial stock of sturgeons in the sea may be corroborated by the number of anadromous migrants in the Volga River. Between 1970 and 1980 the biornass of the spawning population of' the Russian sturgeon was 37,800t, during 1981-1990 it decreased to 18,800 t, in 1995 to 2,200 t. In 1975- 19S0 the mean number of the Russian sturgeon that were passed ta remaining spawning grounds in the Volga River was over 2 million fish, during 1981-1985 it decreased to 477,200 fish, in 1995 to 90,000 fish. The commercial stock of the sevruga also undergoes considerable changes. The maximum commercial stock (5,400-8,100 t) was recorded in 1983-1990. The increase in the number of anadromous migrants of sevruga was produced by recruitment into catch of abundant cohorts which originated from wild stock and were produced at hatcheries. During 1991-1995 the lowering in the biomass of the sevruga spawning population to 2,860 t was recorded. Only 127,500 breeding fish are passed to spawning grounds which is few as compared with an average multi-year value. The biomass of the spawning stock of the beluga sturgeon diminishes gradually. lt was 2,600t in 1970 and decreased to 700 t in the early 1990s, to 300 t in 1995. The number of the beluga sturgeon passed above the fishing zone has been reduced from 6,500 fish to 3,800 fish. A I P EMPFRATURE4NPticEP OVARIARATFieStAN;THEYMI STlRGEON: Acipeneettesmontanus

avier. Linares-Casenave o an Eenennaam, and er Department of Animal Science, University of California, Davis, CA. 95616, U.S.A. Abstract. Observations made on captive broodstock at California farms provide strong evidence that the white sturgeon requires a prespawning cold water treatment if maturation and ovulation are to be completed successfully. Elevated water temperatures (18-22 °C) promote growth, vitellogenesis and early sexual maturity in white sturgeon. However, when the oocytes are near completion of vitellogenic growth phase, holding females at such temperature resuits in ovarian atresia. Ovarian atresia in chondrosteans has been described in Acipenser ruthenus (Faleeva, 1965) and in the white sturgeon (Webb, 1992). We have initiated investigations of the ovarian atresia in the white sturgeon and present preliminary observations on the onset and the course of temperature-induced follicular attrition. Ovarian vitellogenesis in domestic white sturgeon takes 16-18 months, and the oocyte growth is completed in February-March. Late vitellogenic and post-vitellogenic development includes germinal vesicle migration (GVM) which starts in November- December. Final ovarian maturation, induced by hormonal treatment occurs during the months of February-June (Doroshov et al., 1996). In 1994 and in 1995, we exposed two gravid females to warm water temperatures (18- 20 °C) while keeping two others as controls at seasonal water temperatures (12-16 °C). In 1994 we applied the temperature treatment before the completion of vitellogenesis while in 1995 we applied treatment alter the oocytes had reached maximum size and responded in vitro with germinal vesicle breakdown (GVBD) to progesterone (in vitro MIS in sturgeon). We sampled fish with approximately one month intervals and collected blood plasma for measurement of estradiol and androgens using RIA's and of vitellogenin (ELISA; Linares-Casenave et al., 1994), ovarian follicles for determination of egg diameter and oocyte polarization index (Pl, distance of the GV from the animal pole : oocyte diameter), and ovarian tissue biopsies. The biopsies were fixed in modified Karnovski's, 10% buffered formalin, or Bouin's fluid, and embedded in glycol methyl acrylate (GMA). Semi-thin sections were stained with hematoxylin and eosin (H&E), periodic acid Schifft (PAS), and toulidine blue. The experiment in 1994: One female, in a more advance stage of ovarian maturity (egg diameter 3.3 mm, PI 0.2), initiated ovarian atresia in three months alter initiation of temperature treatment. Germinal vesicle migration (GVM) in this fish was arrested soon alter initiation of treatment, and plasma E2 concentration decreased to 0.2 ng/m1 in June, when the atretic follicles were clearly visible. Second female had less advanced oocytes (diameter 2.9 mm, PI > 0.3). It responded with temporary arrest of the GVM and oocyte growth, but continued normal ovarian development during the summer and was spawned in early spring of 1995, atter transfer te cool water during the fall. Plasma estrogen in this female decreased to 10 ng/ml in June 1994. In both fish plasma androgen gradually declined from Mar. 29 on, reaching lowest concentration level by the end of June. Plasma vitellogenin in temperature treated fish followed the same graduai decline as E2 from 8.35 ± 1.19 mg/mi in Mar. 4 to 30.19 ± 20.53 pg/mi in Oct. 24, (mean ± s.e.m, n.2). The two control fish were kept in seasonal temperatures of 12- 16 °C and were successfully spawned on May 6 and 20. E3 -O ISS 97 AGEIVIENT OF LAKE STURGEON SPORT FISHERIE

T..urtissleigLegittitarry Hildebrarid..arect«:DùarerRa.d16 R.L. & L. Environmental Services Ltd., 17312 - 106 Avenue, Edmonton, Alberta, Canada T5S 1H9

The lake sturgeon (Acipenser fuivescens) is the only species of sturgeon found in Alberta. Populations are resident in the North and South Saskatchewan rivers, with this distribution representing the westward limit of their distribution in North America. Because of their unique habitat requirements, restricted distribution, and relatively low abundance, lake sturgeon in Alberta have received special management attention for over 50 years.

HARVEST LEVELS Lake sturgeon harvest was prohibited in Alberta from 1940 to 1968, alter which a limited harvest was again permitted, but only as a hook-and-line sport fishery. After being reopened the fishery was primarily managed as a "trophy" fishery with a minimum size limit of 1.0 m total length and an annuel creel limit of two fish. Angling pressure has increased substantially over the past two decades, with a large a majority of the fishing pressure concentrated on the South Saskatchewan River and focusing on a smail number of weit known locations, The North Saskatchewan River population has been relatively unexploited, only recently experiencing increaSes in sport fishing activity. Few research studies have been undertaken on lake sturgeon in the province, and biologists have relied primarily on anglers ta establish population levels. Sport harvest statistics have been compiled annually rince 1968, through mail-out questionnaires sent to ail holders of sturgeon angling licenses. The 10-year response rate, from 1985 ta 1995, has been 78 percent. Recent data from the survey has indicated that while the total catch is increasing, the percent of fish kept (legat size) and the average size is decreasing.

HABITAT STATUS In Alberta, major consumptive uses of water have contributed to depletion of lake sturgeon habitat in the South Saskatchewan River system. In addition, the Gardiner Dam in the province of Saskatchewan has isolated populations in Alberta from the remainder of the river system. North Saskatchewan River populations have been impacted to a lesser degree by flow alterations due to headwater hydroelectric dams and water quality changes caused by industrial and domestic wastes. Only a few critical habitats for lake sturgeon have been documented in the North or South Saskatchewan rivers. Studies initiated in 1985, through use of radio telemetry and returns of conventional tags, monitored extensive (up ta 270 km) spawning-related movements and identified one probable spawning area in the upper South Saskatchewan River. Observations from these studies, and a recent program on the North Saskatchewan River, suggest that many adult sturgeon remain within home territories between spawning periods, with local movements for feeding purposes. ln some cases extended movements to suitable overwinter habitats may occur. Early life history (rearing) habitats have not yet been identified in either system. E3 - P 3" ISS '97 ASEWRIVER i.--WMITESTuege:»4

Weeke:: R.L.&L. Environmental Services Ltd., 17312 - 106 Avenue, Edmonton, Alberta, Canada, T5S 1H9

BACKGROUND White sturgeon (Acipenser transmontanus) reaches its northernmost distribution in Canada in the Fraser River drainage of British Columbia. The Fraser River is one of the largest rivers in North America, with a drainage basin of nearly 230 000 km. Major flow diversions and dam construction have regulated several tributaries, but the Fraser River mainstem stil' flows unhindered over its 1350 km length. White sturgeon are encountered throughout much of the Fraser River and some of the langer tributaries. Historically, white sturgeon were abundant in the Fraser River, but large commercial catches in the late 1890's and early 1900's resulted in a dramatic decline in abundance which has persisted to the present. lncreased sport fishing activity since the 1970's, declining catch success, continued habitat degradation, and unexplained mortalities of over 35 large white sturgeon in the lower Fraser during 1993 and 1994, resulted in a moratorium on sturgeon harvest in 1994. Catch and release angling is stil' permitted. Little information exists on the life history and habitat requirements of sturgeon populations within the Fraser River. Spawning areas have not been identified in the system and only general information is available on fish distribution and abundance. To address the lack of research and management data, a large scale, mutti-year survey of white sturgeon and their habitat in the Fraser River watershed was initiated by the Fisheries Branch, BC Ministry of Environment, Lands and Parks (MELP) with funding from the Habitat Conservation Fund. Studies began in 1995, with the objectives of determining distribution, describing habitat preferences, and identifying spawning areas of white sturgeon. Because of the immense size of the drainage basin, studies have initially focused on specific geographical areas within provincial Fisheries Management Regions in the Fraser River drainage basin.

REGIONAL PROGRAMS Programs in the upper Fraser drainage (Region 7) are focusing on the Nechako River, a tributary system severely regulated by flow diversion since 1952. Populations in this system have been designated as "critically imperilled" or "endangered" by the BC Conservation Data Centre. Study components include an assessment of distribution, collection of life history and genetic parameters, mark-recapture for population estimates, radio tagging to determine movements, seasonal behavioral patterns, and identification of spawning locations. In the middle reaches of the Fraser River (Regions 5 and 3), the initial objective was to determine the presence/absence and distribution of white sturgeon in the mainstem river based on angler surveys of catch and release activities. Subsequent life history and movement data collection (radio telemetry) have also been adcled. In Region 2 (the lower Fraser River mainstem), the program focus is the identification of spawning locations, by using radio telemetry to monitor the activities of reproductively mature sturgeon. A majority of fish have been collected by angling, with 53-p ISS 97 EON (Acipenser sturio L., 1758) IN UA LQUI wATERRgpoLATIPWANDHoviERFIsHING DECCA fernândez-Pasquie P.O.Box 287, 11.540 SanIticar de Bda, Cadiz, Spain.

Abstract. Sturgeon (Acipenser sturio L., 1.758) was a common specie in Guadalquivir River until thirties. In 1932 was built a dam in spawning area, 100 Km from the mouth that stops the migratory flow. Same year start run a caviar and sturgeon smoked flesh factory. This time most of the fishes corne to the factory from the dam area, but the use since 1934 of a fishing line without bait, specific for sturgeon catch, enable fishermen to work in deep fioles of lower estuary. Gravid females only get spawning areas downstream the dam when the sweet water flow is bigger than 100 cubic. m /sec. Dry springs were more and more fréquents because drought and water regulation for irrigation producing a near continuous reproductive failure. In dry spring was more probable to catch fishes in lower estuary because fishes remain settle in deep holes awaiting sweet water to upstream the flow. Increasing catches in this area involve taking out most of potentially reproductive adult fishes before they have chance of spawn with consequent troubles for the population.

E -P 3 ISS '97 ATIAL DISTRIBUTION OF JUVENILE STURGEONS Acipenser s THE GIRONDE ESTUARY BEFORE THEIR FIRST JOURN Y THE SE

Rochard ::an: azeau:. 1 : Cernagret : French Institute of agricultural and environmental engineering research 50 avenue de Verdun, B.P. 3, 33612 CESTAS cedex, France

The European sturgeon is an amphihaline migratory species that breeds in the fresh waters of rivers in early summer. The juveniles then spend around two years in the sait waters of the estuary zone before moving out to sea. This study describes the spatial distribution from October 1994 to August 1996 of juvenile sturgeons (A. sturio) born in the Gironde watershed in the summer of 1994. For the purposes of the study, the inland section of the Gironde estuary was trawied several times. The trawis - average duration 32 minutes, average length approx. 4000 m - were conducted according to a sampling plan, stratified into 11 major zones from the euryhaline to the oligohaline sectors of the estuary. The study shows that the first A. sturio of the 1994 cohort (LT = 27 cm) were caught in eariy March 1995 in the zones furthest upstream. A distinction appears between an initial period, in which the fish live mainly in the upstream zones of the saitwater estuary, and a second, starting from their second growth period (April 1996), in which the juveniles are split into two separate areas about twenty kilometres apart. The two zones do not appear to be any different te their neighbours as regards depth and type of bed, and are situated 18 km and 38 km respectively from the mouth of the estuary. There is no significant biometric difference (size, weight) between the juveniles of the two zones. However, individuel marking has helped highlight exchanges of animais between the two sectors. The study shows that, within this large estuary of relatively homogeneous depth (4 te 10 m) and type of substrate (sandimud, gravel), the juveniles inhabited two quite distinct sites in 1996. E3 - P 3- /55 -97 ABITAT UTILIZATION BY JUVENILE LAKE ulvescens) IN A NORTHEASTERN ONTARIO

Large River Ecosystem Unit Ontario Ministry of Natural Resources, Timmins, Ontario, Canada

The Groundhog River is one of five main tributaries making up the Moose River Baain in north-eastern Ontario. Hydroelectric development has resulted in the alteration and fragmentation of lake sturgeon habitat across much of the Basin. The Groundhog River is relatively undeveloped and contains a healthy, unexploited population of lake sturgeon. This study focused upon seasonal habitat use, seasonal and diel movement of juvenile lake sturgeon along a central, thirty kilometre section of the Groundhog River. Short duration gilinetting was carried out during daylight and darkness hours over spring, summer and autumn seasons. Captured lake sturgeon were measured, marked and released and habitat parameters were measured as nets were retrieved. The study area was inhabited primarily by juveniles. Captured lake sturgeon were between 1+ and 29+ years of age (mean age = 8.41 years). Total lake sturgeon abundance was estimated to be 3449 +1- 550. Capture rates, age and size distributions did not differ between netting seasons. Lake sturgeon were most active near sundown and immediately following sunrise. Activity was lowest from midday until early evening. Diel activity patterns, indicative of increased foraging behavior were most pronounced in the summer and autumn, when flows were lowest. Lake sturgeon tended to utilize shallow water (<3.0 meters) habitat during periods of highest activity and deep water throughout late morning and afternoon hours. Lake sturgeon exhibited the highest degree of habitat specialization during the freshet. Discrete pools, 6-10 meters in depth, played important roles as refugia in the spring. During this period large congregations of lake sturgeon were found in pools white very few were captured in shallow and nearshore areas, where flows were highest (Figure 1). As the freshet subsided, lake sturgeon became more abundant in shallow water habitat (e.g, channel margins) and less abundant in pools. Most lake sturgeon utilized depths exceeding 6 meters during the freshet and a wide range of depths throughout subsequent netting periods. Lake sturgeon were rarely found at velocities exceeding 70 cm sec. at any time during the study. Lake sturgeon exhibited the highest preference for substrates containing large components of coarse and organic materials where benthic organisms were likely moat abundant. They were found over a greater variety of substrate type 8 during the summer and autumn periods. A3 - O ISS '97 :EFIIMIgNTL.STUM:gS0.N::THERIVIALe:EHAVI:09 Ni>pme: :CTWITY.RHYTHMS OF JUVENILE :ATLANTICSTURGEON (Aeipeeser.sturio.

Staalça,«f: Kirsollbaum 1140 Institute of Freshwater Ecology and Inland Fisheries, Mueggelseedamm 310, 12587 Berlin, Germany

Summary: Experimental studies on thermal behaviour and die! activity of Atlantic sturgeons were performed using an electronic temperature shutllebox design. The fish showed diel activity rhythms with highly dominant 24 h frequencies. They proved to be night active fishes. The maxima and minima of activity and swimming speed were found to be at 5.00 a.m. and 19.00 to 20.00 p.m. respectively. No clearly preferred temperature range =id be determined though the activity and swimming speed proved to be temperature dependent. A similar effect of weak or no temperature preference could formerly only be registered for zebrafish (Danio rerio).

Most species of Acipenseridae are worldwide threatened or nearly extinct. In Western Europe this applies in particular to Acipenser sturio. The Iast irregularely naturel reproducing population exists in the river Gironde, France (WILLIOT et al. 1997). It seems to be unrealistic to carry out behavioural studies on the first life stages in the wild. So any information, even experimental ones, couid be helpful to better understand the ecology of these young fish and to improve the rearing conditions before restocking. Due to our experiences and to the Tact that some progenies were obtained in 1995 by the team of Dr. Williot (Cemagref, Bordeaux) a cooperation program Mas been established on this critically endangered species. The „Maximum Power Principle" means that successful biological systems maximize the flow of useful energy. This process is strictly controlled by the body temperature. BRYAN et al. (1990) hypothesized, that this principle applying to teleost fish wiii result in a distribution within a temperature gradient in accordance ta the achievable amount of surplus energy. This would lead to a preferred temperature range. We formerly studied these aspects in cyprinid species (STAAks 1996). If this principle generally determines the thermal behaviour of fishes (WARE 1982), it would be interesting to study non- teleost fishes e.g. sturgeons in this respect. We tried to determine the preferred temperature ranges, in an electronic thermal shuttlebox design (McCAuLEY 1977, SCHURMANN & STEFFENSEN 1992). A 600-I aquarium was divided by a plastic watt which had a hale at the bottom allowing the fish te move between the two sections. The temperature was regulated by both a cooling device and electric heaters. Ail measurements and controls were managed by a computer. The fish's activity was registered by the count of impulses at 40 infrared photocells (activity) and by the time length cf these impulses (duration). Activity divided by duration resuits in a factor proportional ta the swimming speed in bodylengths per second. The principle of an electronic shuttiebox design allowed the fish te control the water temperature in the basin. A maintained temperature difference of 2 K between the chambers presents an instantaneous spatial temperature gradient guiding the fish. When the fish were more attracted by the warmer compartment, the temperature of the whole device was raised, if more fish moved to the colder compartment the temperature of the whole device was lowered. We started with a 10 days acclimation period at 21°C. The whole test Iasted for 80 days. Atter 35 days the temperature gradient was reversed, that means the E3 P /55 '97 'IRE HISTORY CHARACTERISTICS OF HUDSON RIVE STURGEON (Acipenser oxyrinchus) AND DEL F ANAGEMEN ai T.. Stévensorr ailé David Seo , Chesapeake Biological Laboratory, Center for Estuarine and Environmental Studies University of Maryland

Atlantic sturgeon support a commercial fishery in the Hudson River. We investigated the lite history of this population through microstructural and microchemical examinations of hard-parts and demographic analysis. Interpretation of annuli in sectioned pectoral fin rays provided an unbiased and precise method for ageing juvenile and adult Atlantic sturgeon. On average, we observed five fewer annuli in sagittal otoliths than in fin rays. Annulus formation was validated by marginal increment analysis and oxytetracycline marking of juvenile laboratory-reared sturgeon. von Bertalanffy growth model parameters (females, K. 0.08, L. 251 cm ; males, K. 0.25, L. 179 cm) predicted a higher growth rate for males than females. Females, however, attained a higher maximum age (42 years) and size (TL = 277 cm). Modal ages of spawning males and females were 16 and 19 years, respectively. Males are being exploited at a higher rate than females. Lower exploitation of females is probably due to their reduced frequency of spawning relative to males. Spawning frequency was estimated using interpretation of bands of narrow annuli, "spawning beits", and periodogram analysis of annular width measurements. Modal spawning frequency as determined by spawning beit analysis was 4 years for females. Annuai patterns of strontium and calcium, observed using microprobe analysis of fin ray sections, were probabiy related ta annulus formation rather than migratory behavior. Life history characteristics and neural and bycatch mortality estimates were inciuded in an age-structured egg production per recruit model te estimate the response of this population to various fishing strategies. By choosing a higher acceptable egg production threshold (50% of the unfished egg production per recruit) as recommended by Atlantic States Marine Fisheries Commission, sturgeon fishery managers can avert the risk associated with managing a species that is long-lived and matures late in lite. The model is net sensitive to spawning frequency (3 yrs.- 5 yrs) but is sensitive to estimates of natural mortality and growth parameters, K and Because Hudson River Atlantic sturgeon are caught incidentally in several coastal fisheries, any harvesting strategy must include conservative management options.

Growth rates of Acipenseridae are apparently affected by differences in migratory behaviors. Atlantic sturgeon showed higher growth coefficients and higher relative fecundity than semi-anadromous or freshwater resident species. We speculate that these traits are linked to their anadromous lite history, which is shared only by two other species of sturgeon (A. sturfo and A. medirostris). E3 - 0 3d 155 '97 TENTIAL USE 0F CULTURED ATLANTIC STURGEON F RESTORATION OR ENHANCEMENT I P

Richard St. Pierre U.S. Fish and Wildlife Service 1721 N. Front Street Harrisburg, Pennsylvania 17102 USA

Abstract. Stocks of anadromous Atlantic sturgeon (Acipenser oxyrhynchus) on the East Coast of the United States are severely depleted due to past over-fishing, habitat lors and degradation. The Atlantic States Marine Fisheries Commission (ASMFC) has developed a fishery management plan which establishes a goal of attaining self- sustaining stocks which can support commercial fishing throughout the species range. The highest priority management recommendations of the ASMFC plan are to control harvest through fishery closures and to identify and protect critical spawning and nursery habitats. Recommendations relating to population restoration or enhancement include encouraging an expanded aquaculture effort ta develop techniques to rear Atlantic sturgeon and to provide guidelines to the states for culture and restoration stocking. The U. S. Fish and Wildlife Service's Northeast Fishery Center (NEFC) at Lamar, Pennsylvania accepted the challenge of developing basic sturgeon culture techniques with a goal of producing a culture manual for Atlantic sturgeon. The Hudson River currently supports the only relatively heatthy nearby source of broodfish and NEFC has worked closety with New York State -and several federal research laboratories since 1991 to collect, hold, and transport mature sturgeon from the Hudson River for spawning trials. In each of the last four years (1993-1996), mature Hudson River Atlantic sturgeon were hauled ta Lamar by specially equipped transport system, and successfully spawned using hormone injections. In October 1994, 5,000 cultured fingerlings, marked with fin clips and coded wire tags, were stocked back into the Hudson River. Recovery of marked sturgeon yearlings 8-12 months later indicated that these fish grew well, spread themselves out over a 92 km range, and comprised almost 60% of ail presumed age 1+ fish in collections. ln a separate trial in July, 1996, approximately 3,500 cultured yearling sturgeon were stocked into the Nanticoke River in Maryland. These fish were also marked with internai wire tags and some larger individuals also carried externel streamer tags or sonic transmitters. A $100 per fish reward program is in place in Maryland waters of the Chesapeake Bay for incidental captures and numerous tagged sturgeon have been recovered, rneasured, and released to date. The author chaired a subcommittee which developed a breeding and stocking protocol for this species. The protocol discusses broodstock selection criteria, genetic implications associated with in-river or inter-basin stockings, effective breeding population sites for use in enhancement or restoration programs, production and stocking objectives, and evaluation criteria. The protocol also catis for a thorough coastwide genetic analysis of Atlantic sturgeon subpopulations. Without active intervention, such as a long-term commitment to using cultured fish, many river-specific sturgeon stocks on the U. S. Atlantic Coast may soon be extirpated. E3 - 0 ./.9.9 '97 tYLI:FE:111STPRY:AND:rp.pulATtçe.isTe CIR E .:upggqN:Apip.Onset0ityitynesbuÉeleg.0t01 .1111fER;.:Ft..0:131

Sulak, and James Clugst

Abstract. The Gulf sturgeon, Acipenser oxyrinchus desotoi, is a threatened species for which spawning, earfy life history, population structure, and habitat use information has been lacking. We investigated these life history aspects in the Suwannee River, Floride, one of the few un-impounded, relatively unimpacted rivers used by the anadromous Gulf sturgeon. The Suwannee River population is the largest extant population of the species, and perhaps its only regularly reproducing population. Egg collection with substrate buffer pad samplers over four years identified a spawning site 215 km upstream from the Suwannee River mouth. Physical and hydrographic characteristics of the spawning site were defined by acoustic Doppler current profiling, bottom sounding, and underwater photography. Eggs were deposited only on the side of the river characterized by numerous eddies, including a persistent major eddy with reverse bottom current (locally flowing upstream at 11-42 cm s-1). The egg deposition substrate consisted of a 2-4 m depth bedrock platform of eroded limestone overlain by a 0-10 cm deep layer of clean fine sand, and densely popuiated with elliptical, randomly spaced, 4-10 cm diameter calcium carbonate pebbles. The spawning site, the only such site yet identified, lies 15 km below a major geological scarp. Differential water sources (surface runoff vs spring ground-water) above and below the scarp may determine the upstream boundary of suitably stable conditions for embryonic development. In both 1995 and 1996 spawning began 6-7 deys after the March new moon; in 1996 a second round of spawning took place, beginning upon the Aprif new moon. Eggs were deposited al water temperatures of 17.5-21.2 °C in 1995, 14.9-22.7 °C in 1996. Several discrete spawning events were indicated in each year based on developmental synchrony among new eggs collected on a given day. Spawning appears to be nocturnal; fish appear net to remain on the site after spawning is accomplished. Some mature fish appear to immigrate too late to accomplish spring spawning at suitably low temperatures. Fall capture of females laden with large black eggs and males with flowing sperm suggest the possibility of fan spawning prier to annuel emigration to the Gulf of Mexico. Mufti-gear sampling throughout the river has resulted in the capture/observation of 19 riverine young-of-the-year (YOY) (82-371 mm TL). Developing YOY were Pound from km 33 to km 237, primarily on sand shoals along open straight stretches of the river. Contrary Io earlier speculation, no particular association of YOY with naturel springs appears to occur. Our capture data suggest that young fish remain in natal fresh water habitat for at least the first 6-10 months of life, attaining a length of 350-450 mm TL. Their initial downstream migration to the estuarine river mouth occurs in January/February. Older riverine juveniles (ages 2-4) travel with sub-adults and adults, annually migrating to the river mouth in October/November, returning upstream in March/April. However, individuels younger than age 5 remain in the vicinity of the river mouth over winter, and do net moue offshore with older fish. Fall net census of the emigrating sub-adult/adult population in 1995 revealed a polymodal size-frequency. The main population mode centered upon 1450-1500 mm E2 - O ISS '97

D0-RING:pFtEspANibm

eroistogarkov••a, VNIRO, 17, V.Krasnoselskaya, Moscow, 107140, Russia.

Summary. The number of acoustic signais produced by spiny sturgeon during the prespawning period is correlated with the state of male readiness ta let out the sex products. Males of spiny sturgeon produce tone and spectral sounds like "whisties". Frequency spectrum of this signais is up to 16 kHz.

Abstract. Many sturgeon species during prespawning period produce tone and spectral sounds like "whisties". Acoustic activity of spiny sturgeon was studied more completely. The sounds emitting by two males of spiny sturgeon were hearing and recorded on tapes during 56 hours. The technical parameters of the hydrophone and tape recorder was able to registrate acoustic signais in the frequency range of 0.1 - 20 kHz with the sound pressure more then 0.5 Pa. In the beginning of acoustic observation two males of spiny sturgeon were in the tank together with Iwo females of small sturgeon (Acipenser ruthenus). ln 4 hours the males were piaced in the another tank. After 15 hours ail fishes were injected by hormonal spawn inductors. The first spermination in males started in 28 hours (ait sperm was taken). In 4 hours sperm of each males was taken twice as little. About 500 acoustic signais produced by the males were recorded on the tapes. For frequency analysis of the signais the PC based "Biooptima" system with "Gruel and Kjar" equipment (filter 1617A, amplifier 2650) have been used. Analysis of the most intensive signais (comparing to the noise level) shown the following: • 25 % of signais can be identified as tone signais ol type "whistle". This signais have 1 - 4 amplitude modulated harmonica! components. The frequency of harmonica is constant. The first harmonic is the most intensive. The frequency of the first harmonic is usualiy in the range of 2 - 3,7 kHz and the highest harmonic - as a rule up to 9.3 kHz, and some times - up to 12 kHz. • 75 % of signais can be named as spectral signais of 3 types: "whistle FM" which have frequency modulated harmonical components (30 % from number of spectral signais), "whistle-noise" (60 %), "whistle-thump" (10 %). Frequency spectrum is usuaily up to 6 or 9 kHz and some times up to 16 kHz.

- The number of signais produced during the time period is correlated with the state of male readiness to let out the sex products.( Look Fig). 63 - P 3,d ISS 97 MITIÇ:':STUfflEOW,FISFIERY"'MANAGeMEN7(IN TH; R

.Guy.Trenéia and.GLiy:Verreault Quebec Department of Environment and Wildlife

Abstract. The Atlantic sturgeon (Acipenser oxyrinchus) is an anadromous species that is commercialy fished in the St-Laurent river, Canada. Ail over its distribution ranging from Labrador to Florida along the Atlantic coast of north America, the species supported a fishery of 3500 tons a hundred years ago. It was estimated that in 1992, it yielded around 200 tons of which 129 were from the St- Laurent river. Between 1940 and 1966, the St-Laurent fishery had roughiy stabilised under 60 tons; it vanished ta nothing between 1966 and 1975 and climbed back to over 60 tons after 1981. The harvest grew progressively peaking at 140 tons in 1990 and started to decline naturaily toward a 100 tons in 1994. Since then, different pieces of legislation were put in place to lower the harvest around its former lever of 60 tons even if this figure is very approximative. These legislation include identification of the gillnets used by the fisherman, shortening of the fishing season and a siot in the lenght of the fish legally kept. Surveys were conducted in the last three years to evaluate the success of these reguiations on the fishery harvest. New modifications to the regulations are stil necessary ta reach the objective of 60 tons. The lack of information on the life cycle and on the strategic habitats in the St-Laurent river as elsewhere in its ares of distribution in an aggravating factor for the critical situation of the Atlantic sturgeon. Research is particularily needed to locate and describe the spawning habitat of the fish in order to protect its habitat and obtain information on its spawning requirements.