1. Overview of sturgeons related activities in HAKI by András Rónyai
Visit of WWF delegation to HAKI
Szarvas
Overview of sturgeons related activities in HAKI by András Rónyai
Research Institute for Fisheries, Aquaculture and Irrigation
Anna-liget 8., H-5540 Szarvas, Hungary

2. Sturgeons – due to excellent meat quality and mainly their roe – are ones of the most valuable fish species.
All 27 species of sturgeons worldwide are vulnerable, endangered, or critically endangered due to: Overfishing and poaching; Habitat degradation; Dam and hydropower constructions; Water pollutions; Biological features of their life (late maturity and long reproduction cycle); and many others (i.e. loss of genetic diversity, destruction its integrity, climate changes, etc).

3. World sturgeon fisheries and aquaculture.
(FAO, Fishstat+ 2011)

4. Documented catches of endangered sturgeon species in the Hungarian waters since the beginning of the 20th century Danube

5. Conservation and restoration of the endangered sturgeon populations in the Danube River Basin.
Action Plan for the conservation of Sturgeons in the Danube River Basin
Basin-wide coordination of sturgeon policy and best-practice management,
Legislation and enforcement controls for sturgeon fisheries and trade,
Conservation of sturgeon species and populations, including their genetic integrity,
Protection, management and restoration of sturgeon habitats, including reopening of migration routes.

6. General requirements for the rehabilitation
Habitat rehabilitation
Aquaculture
Restocking
Monitoring
International and national collaborations

7. Basic elements of the recovery programmes.

8. Objectives of sturgeon cultivation.
The objectives are either:
Production of fingerlings for restocking natural waters (the culture period is fairly short, usually days are needed to produce 2-3 g nursed fry or fingerlings);
Production of marketable-size fish (2 – 4 years depending from species and market preference);
Production of roe for caviar ( years).
Recreational (angling), educational (i.e. fish-watcing) purposes.

9. Goals of the production for different purposes
Commercial aquaculture
Adaptability to artificial conditios,
High growth rate,
Disease and stress resistance,
High survival,
High feed utilization efficiency,
Size homogeneity,
Early sexual maturation,
Short reproduction interval,
High fecundity, etc.
Restocking natural waters
Adaptability to "nature",
= need to farm for fitness for survival in nature
Reduction of inbreeding, saving ecologigal groups, training fry to "wildlife".
Selection, inbreeding, crossbreeding, hybridization, etc.

10. Broodstock rearing and management
Broodstocks can be originated either from:
Capture from the wild (during spawning migration);
Captured and domesticated in aquaculture conditions (tanks, ponds, raceway);
Captive (propagated and reared under controlled conditions).

11. Induction of final stage of gonadal maturation
Final stage of maturation can be stimulated by:
Ecological factors (temperature, flow rate, daylight regime),
Physiological methods
Pituitary gland (hypophysis) of sturgeons, or carp;
Gonadotrop-releasing hormons either alone
des-Gly10(D-Ala6)-LH-RH Ethylamid
des-Gly10(D-Phe6)-LH-RH Ethylamid
azagly-nafarelin, etc.,
or in combination with dopamin-antagonist (i.e. metoclopramid)
Combination of the above treatments
Despite the highly effective hormonal inductions it is desirable to continue the development of ecological stimulation.

12. Collection of gamets
Milt is obtained from the males by pressing the abdominal wall, exuding it from the genital pore in a thick jet. (One male can be stripped several times in a period of a few hours, and milt can be refrigerated at 1-4 °C for one or two days without affecting its viability.)
The beginning of ovulation is indicated by the appearance of few eggs, either spontaneously or by a gentle pressure on the abdominal wall.
(Stripping should be started 1-2 hours after the appearance of the eggs.)
Eggs can be obtained either:
From the previously killed fish,
By method of Burtzev (through a 8-10 cm incision made in the abdomen),
By method of Podushka (through an incision in the caudal section of the oviducts).

13. Fertilization
Sperm are highly mobile for 5-15 minutes in water.
Eggs are capable for fertilisation for 5-10 minutes in water (and have several micropiles).
Before fertilization the coelomic fluid - which hinders sperm’s mobility - should be removed.
There are three methods for fertilisation:
Dry (eggs and milt are mixed, and diluted with water),
Wet (before fertilisation eggs are washed and then milt is added),
Semi-dry (In order to avoid polyspermy the milt is diluted in water in a ratio of 1:200.)
Our resulted demonstrated that the wet method gives better fertilisation rate in sterlet, Siberian sturgeon and paddlefish.

14. Treatments of fertilised ova and incubation
Two or three minutes after mixing sperm and eggs together, a liquid suspension should be added to eliminate stickiness of the eggs. (The fertilized eggs are stirred gently in this solution for minutes. Following solutions can be used: Silt (made up of 0.5 kg silt in 4 l of water (Milstein, 1972); Talcum (0.1 kg in 10 l water); Household starch (0.5 kg in 1 l water) according to Jaczo (1969); Woynarovich-method (Solution of urea (0.4%) and NaCl (0.3%) for 5-10 minutes, followed by rinsing with 0.1% tannin solution); Milk (Nagy et al., 2008)
However in the nature eggs are attached to different substrates!
Our results on sterlet (and common carp) demonstrated, that attached eggs can be succesfully incubated with good hatching rates.

15. Larvae and fry rearing ensure water supply with water of good quality,
In order to ensure optimal conditions for rearing and to increase the fitness of the fish for survival in the nature it is desirable to:
ensure water supply with water of good quality,
feeding with diets of adequate quality and quantity,
maintain the day-light regime close to natural with slight temperature fluctuation of the incoming water,
train the fish for different water velocity,
paint the bottom and wall of tanks in corresponding colour of their natural habitat,
stocking some small predator fish in the nursing environment,
etc (i.e. sound, smell, taste)

16. Research on sturgeons in HAKI
Research on sturgeons started from the beginning of sixties.
Artifiticial propagation,
Rearing technology,
Nutrition and feeding,
Physiology,
Molecular genetic researches,
Stock assessement in rivers,
Collection of sturgeon species.

17. Sturgeon gene conservation in HAKI
Gene bank of sturgeons since 1988 (5 native and 4 allien species)
Native species:
Sterlet (A. ruthenus)
Russian sturgeon (A. güeldenstaedti)
Stellate sturgeon (A. stellatus)
Ship sturgeon (A. nudiventris)
Great sturgeon (Huso huso)
Allien species and subspecies:
Siberian sterlet (A. ruthenus marsiglii)
Siberian sturgeon (A. baeri)
Russian sturgeon – Caspian stock (A. güeldenstaedti)
Paddlefish (Polyodon spathula)

18. Species in the gene bank of HAKI
Great sturgeon
Russian sturgeon (Black and Caspian sea „forms”)

19. Ship sturgeon
Sellate sturgeon

20. Siberian and Danube „forms”
Sterlet
Siberian and Danube „forms”

21. Paddlefish
Siberian sturgeon

22. Further actions in gene bank maintenance
Improvement of the culture technology (according to different production purposes),
Increasing the individual's number of native endangered species,
Individual tagging,
Genetic analyses to avoid inbreeding and hybridization,
Cryopreservation, sperm gene bank,
Improvement of the culture conditions.

23. THANK YOU FOR YOUR ATTENTION!