1. Reproductive adaptations of haarder (Liza haematocheila) to the new environment of the Russian South Seas Svetlana Pianova Federal Research Institute of Fisheries and Oceanography (VNIRO), Moscow, Russia ICES Annual Science Conference 20–24 September 2005

2. Introduction In the 1990-s the Far Eastern mullet haarder assimilated and naturalised from the Far East into the Black Sea and the Sea of Azov. The increasing in the abundance of the population has made it the commercial fish species which provides TAC of 12 430 t in 2006. The adaptations to the new environmental conditions have an effect on fish reproduction system. We have analyzed reproductive adaptations of mullet haarder to the new environment during the adaptation period to an intensive fishery.

3. Materials and methods The haarder specimens were collected by pelagic trawl and fixed nets. We analysed 1688 fish samples from 6 introduction area places the Black Sea bays and lagoons, the Kerch Strait, the Sea of Azov, the fresh water cooling ponds of the Kursk nuclear power station. and 2 native area places (estuaries and bays of the Primorsky and Khabarovsky Regions). For the histological analyses were used small gonads samples of 260 individuals.

4. Results and Discussion Fish weight and length, condition index, indexes of gonad and liver, fecundity and also vitellogenic oocyte diameters in the ovaries on the IV stage of maturity of the matured haarder from the southern seas exceeded the appropriate parameters of the Far East basin fish (Table 1, 2).

5. Average gonad index of haarder inhabiting different regions. - null data, * - data validity with 0.01 probability. Table 1. Sampling regions Frequency, % Gonad index Prespawning fishPostspawning fish femalesmales femalesmales Kanaki bay9622,027,8±1,01,8±0,34,1±0,4 Sudakskaya bay745,0±9,2*12,3±1,92,7±0,5- Kiziltash lagoons7614,5±3,9*9,7±3,42,1±0,31,4±0,4 Gelendgikskaya bay 9421,7±3,414,3±0,30,93- Kerchensky Strait8012,2211,3-- Sea of Azov886,4±3,5*12,7±2,5*5,9±0,7*0,8 Primorsky Region335,2---

6. Comparative reproductive characteristics of haarder from two different areas. - null data, * - data validity with probability >0.05 Sampling region Water T, ˚C Female weight, kg Individual fecundity, million Relative fecundity, eggs/gram Leading oocyte diameter, 10-6 m Far East area 16-18 0,96± 0,10 1,339  0,238 1174,6707,97 Kiziltash lagoons 16-24 1,63± 0,16 1,628  0,028 * 1017,5* 1050,22  11,32 Crimea inshore 21-25 2,36± 0,21 --- Sea of Azov 23-25 3,56± 0,23 --- Table 2.

7. Fish condition varied both in the introduction area and in the Far East native area because of the difference in the ecological and temperature conditions. The matured females of haarder inhabiting all regions can be arranged in decreasing order of the average gonad index in a succession: - the Barabashevka River fish, - the Sea of Azov fish, - the Crimea inshore fish, - the northern Black Sea lagoon system fish.

8. The ovaries of the Black Sea females had 3 groups of oocytes: large and middle-sized groups of vitellogenic oocytes and small-sized group of cytoplasmic oocytes. Unlike that, the Far East females had only 2 size groups of oocytes. Figure 1. Average oocyte diameters in the ovaries of Black Sea females and the Far East females of haarder.

9. The spawning period In the Black Sea lagoon system it lasted from the middle of April to the first decade of July (Norvillo, Pyanova, 2001). In the Primorsky Region it was registered from the end of May till the end of June. The distinction is determined by warmer climate in the Russian South Seas and earlier water warming-up in the Sea of Azov and in the Black Sea (Smirmov et al., 2002).

10. Proofs of the intermitted spawning of the Black Sea haarder The data on size oocytes groups in the ovaries of spawning fish indicated the opportunity of the intermitted spawning by multiple portions for a one spawning season. Presence of females with ovaries on VI (II-III) stage of maturity in the Black Sea.

11. Figure 3. Harder ovary on VI (II-III) stage of maturity from the Sea of Azov, 2001, magnification 20x10. Atretic follicles are indicated with arrows.

12. The postspawning gonads had atretic follicles, vacuolated oocytes and early vitellogenic oocytes at the same time. So, haarder generates 3 portions of oocytes in ovaries. The Azov and Black Sea haarder females ovulate intermitted and asynchronous as all mullets do. However, in the native Far East area the small-sized oocytes generation cannot be realised because of the unfavourable temperature conditions.

13. Ovarian egg diameters and spawning periods of haarder inability different regions. RegionYear Sampling time Ovarian egg diameter, 10 -6 m Spawning period Sea of Azov 2001 middle of June 555,04± 16,41* end of May - June Crimea inshore 1998June445,56± 38,64* May – July Kiziltash lagoons 2000 middle of May 267,46± 5,74* April – July Table 3. *- data validity with probability >0.05 Diameters of the unhydrated oocytes widely varied and decreased after every ovulation because of the reducing of the female plastic reserve.

14. Testes of the two-year haarder from the Kursk APP cooling ponds had a few cytoplasmic oocytes among the spermatogoniums. The histological results indicated the absence of male among the one- year fish. So hermaphroditism began to appear in the gonads of the two-year fish (Mikodina, Pyanova, 2001). Firstly all fry were females, and later gonads of some fish overdeterminated in testes. Therefore, the haarder have juvenile protogynyc hermaphroditism. Hermaphroditism

15. Since 1997 together with normal, small organelles the giant nucleolus (6.03-9.01 x 10-6m in diameter) were founded. Before this study they have not been registered in the haarder oocytes. At the present giant nucleolus are found in the ovaries of haarder in all regions.

16. Figure 4. Cytoplasmic oocytes into the haarder ovaries with normal (N) and giant (G) nucleolus from the Crimea inshore, 2001 (A), the Sea of Azov, 2001 (B) and the Tatar Strait, 2000 (C). G N АВС

17. There were amitotic oocytes in the ovaries of fish from the native area. These facts can not be named normal because they make difficulties for the gametogenesis on the cellular level. Figure 5. The amitotic oocyte in the ovaries of haarder from the Far East area.

18. Conclusion Analyses of reproductive system of mullet haarder after the introduction indicated the presence of adaptations. The Black Sea haarder inhabit at the northern survival limit of the Mugilidae area. Adaptations to the low latitudes are early maturation and intermitted spawning unlike adaptation to the high latitudes. Introduction into the warmer Azov and Black Sea waters resulted in increase in fish weight from 0,96±0,10kg to 3,56±0,23kg and fecundity at 22%, one year early maturity and increase in vitellogenic oocytes diameter at 48.2% on the average.

19. The spawning period lasted longer in the South Seas. Native fish ovaries formed two portions of oocytes, but only the first one developed after resorption. Introduced fish had three-portion spawning as all tropical water mullets do. The appearance of giant nucleolus is coupled with the changing of biosynthesis activity during the previtellogenesis and the oogenesis divergence under the contaminated environment. The South Seas haarder testes have juvenile protogynyc hermaphroditism.

20. Thank you very much for your attention! Thank you Conference organizers!