Danube Delta natural phenomena

Why the Danube Delta
23 January 2018

Danube Delta natural phenomena

Besides the splendor of the beauties from the surface, the Danube Delta has countless hidden wonders. This means that behind every leaf, rotten root and under puddles or, who knows what hidden depths of the Danube, lie unseen creatures, each one trying to render its natural cycle. The wealth consists of the spectacle of the Delta’s natural phenomenons.

You can see here how snakes or lizards hatch, you may see all surface’s specie’s mating rituals. These unique moments are fascinating that is why a visit to our Delta Pension can result in unique photos and unforgettable memories. Many of these species are rare or on the

brake of extinction that is why we do not encourage brutal interventions or the disturbance of ecosystems. We’ve set ourselves a goal to organize theme photo contests for our guests and for the winners we offer free accommodation for at least one weekend. By these means we try to discourage other means of disturbing nature. A few bench marks of the fish from the Danube Delta: THE STURGEON Acipenser gueldenstaedtii Brandt & Ratzeburg, 1833 Spread throughout RBDD isolated specimens in the Danube and its branches Chilia and Sfantu Gheorghe as well as in the Black Sea. Measurments Normal: 100-200 cm, 20-30 kg Max: 236 cm, 115 kg Biology Marine specie, migrating. It lives and winters in the sea at depths that do not surpass 60-70 m.

For reproduction, it swims to streams sometimes at long distances from the river outlet. Specimens were seen in the past as far as Viena. Now it cannot pass beyon the Porţile de Fier dams. As the other migrating marine sturgeons, there are 2 periods of migration: a part of the reproductivesn swim from the sea ti the Danube in February-May with the greatest intensity in April and reproduce in the same year and the other part start migration in August which lasts until November with a maximum in october.

These winter in the Danube and reproduce the following year. Sexual maturity is achieved at about 11-13 years of age for the males and 12-16 for the females, at a body spread of over 1 meter. The mentioned longevity is of 33 years. Reproduction takes place from April until the beginning of June, with a maximum high in May. Reproduction quarters consist of holes of about 8-20 m, with a bottom of clay, gravel or sand, hidden from mud.

A female lays, depending on her body mass, between 29.500-406.800 eggs. Hatching takes place after about 90 hours. After reproduction, adult specimens return to the sea, and the young ones at about 2-3 months when their length reaches approximately 30 cm. The sturgeon does not reproduce in consecutive years, only in 2 to 5 years intervals. Some of the young ones may stay in the lower part of the river for another 1-2 years. Food consists of different types of bentonic invertebrates(shell fish,mollusks and insect grubs), adults feed on other fish too.

Growing pace is stated in the following:1 an-31 cm, 2 years-51 cm and 2 kg, 4 years -77 cm and 4 kg, 6 years-91 cm and 6,5 kg, 10 years-114 cm and 12 kg, 17 years-160 cm and 31,5 kg. Industrial fishing For sturgeon fishing there are used sturgeon baits, ohanes and carmacs. It can be accidentally caught at mackerel bait. Most frequent catches take place on the Danube. After 1950 the quantity of fish drastically drops, the main reason being irrational fishing, until almost extiction level was reached. Therefor in 2005, on the whole Danube area of the Romanian sector, ony 8 species were caught. Over 50% of captures took place in the current RBDD area. Sports Fishing although sturgeon feeds in the Danube too, there are no recorded captures through sport fishing to date at least in the RBDD area.

Nutritious value After sterlet, the sturgeon has the most delicious meat. It can be eaten in any way. Sterlet Blicca bjoerkna (Linnaeus, 1758) Spread in RBDD This is one of the most frequent and abundant species in all fresh waters: Danube, lakes and channels and even the Black Sea close to watter outlets of the Danube. Size: Normally: 15-25 cm Max: 36 cm, 1 kg Legal: 15 cm Biology The sterlet lives in slow streaming fresh of still waters. It moves in groups according to age near the water bottom.

Reproduction takes place in April-June in shallow water areas abundant in vegetation on which it deposits its eggs( 2.500-140.000). Incubation takers 4-6 days. Sexual maturity is reached at 3-4 years. It feeds on bentonic invertebrates, insect maggots. Young specimens also feed on vegetation. Industrial fishing The sterlet is caught in industrial amounts using fishing and pound nets. It is usually mixed with other types of small species like the red eye. Sport fishing It consists of stationary fishing, by raft, when it needs to be searched near the bottom, and by using light rods to fish near the bottom. For the best results, natural baits are used (maggots, worms), but plant bait also works.

Best results are obtained in winter also. Nutritious value Relatively low, very weak taste. The meat is white, low in fat and with lots of bones spread along the spine. In the specified territory it is served fresh( fried, as fish soup, brine). Protection: This specie is not endangered and there are no special protection measures set for it. WHITE BARBEL -Barbus barbus (Linnaeus, 1758) Spread throughout RBDD present all over the Danube trail, whith a great frequency along the Chilia branch, downstream of Murighiol. Size Regular size: 25-50 cm Maxim: 120 cm, 12kg Legal 27 cm Biology Species that lives in big streams, frequent in the flat-open-country. It prefers deep waters, with moderate currents and hard bottom.

It migrates upstream in spring and downstream in autumn. Migration of the Danube population is unknown. Sexual maturity is reached at the age of 2-3 years for males and 4-5 for females. Reproduction takes place from may to June, in areas with deep waters and the current. Spawns, 15.000-150.000 are laid-down on rocks or right on the sand. Incubation takes about 5-15 days. Nourishment consist in a large variety of aquatic invertebrates which live on the water bottom and rarely vegetation, detritus or even small fish. Growing rhythm is slow: 7 cm in the first year, 20-25 cm at 4-5 years and 60 – 80 cm at 10 years.

Industrial fishing In the RBDD is caught sporadicly only on the Danube, especially when fishing with mackrell or sturgeon. Rare specie here, does not enter the economic importance category. Sports fishing In the RBDD area, because of its rarity, the barbel does not represent an objective for sports fisherman, as in other rivers in the country. It’s captured occasionally through bottom fishing in the Danube, practiced at other species. Favorite bates are worms of any kind and fen-cricket. Plant baits work as well. Nutritious value. The barbel has white muscles, fine and tasty, low in fat, with a lot of bones along the spine. Spawns are toxic.

CRUCIAN – Carassius carassius (Linnaeus, 1758) Spread throughout RBDD for the same reasons, the crucian has suffered the same downfall in the whole country being almost extinct. Until the year 1970, the specie was abundant and frequent in most fresh waters, representing interest for industrial fishing. In the last years, thanks to the diminished level of pollution and healing of aquatic habitats, the crucian has stared to grow back its population in some lakes and isolated channels, but it this country it is still considered an rare specie. Size Regular: 20 cm Max.:64 cm, 3 kg Legal 17 cm Biology The Crucian is a fish tied to still waters, relatively deep. It’s resistant to lack of oxygen. Sexual maturity is reached at about 2-3 years. Reproduction takes place in May-July when the female lays about 6.000 – 300.000 spawns, according to size and age, in 4-5 rounds. Hatching takes place after 5-7 days.

Food consists bentonic invertebrates. Growth rhythm is recorded as it follows : 13-20 g at 1 year, 69-160 g at 2 years, 180-250 g at 3 years, 300 g at 4 years. After the year 1983, because of the stocks diminish to near extinction, it does no longer represent any economical importance, fishing being banned a while for population regrowth. Meat usually tasted muddy, being eaten fried and in fish soup. Industrial fishing After the year 1983, because of the stocks diminish to near extinction, it does no longer represent any economical importance, fishing being banned a while for population regrowth. Meat usually tasted muddy, being eaten fried and in fish soup. Sports fishing: does not represent any importance. CATFISH – Silurus glanis Linnaeus, 1758 Spread throughout RBDD ommon specie throughout the Danube way with season and annual fluctuations in great lakes and adjacent channels and sporadic appearances in Razim-Sinoie.

Also it’s encountered in parts with sweet water of the Black Sera. Size Regular 50-100 cm, 1,5-7 kg Max.: 500 cm, 306 kg Legal: 50 cm Biology Fresh water specie which adapts well to salty environment. It prefers deep waters in flowing streams, but it is also found in great lakes with a hard or muddy bottom. Sexual maturity is reached at the age of 4-5 years, at a length of over 50 cm.

Reproduction is triggered at a water temperature of 18-20°C, from April to June. Reproductives group in pairs. A female lays about 60.000-1.000.000 spawns ,depending on size, in shallow and rich in vegetation waters, after which they retreat to the Danube. Incubation time 5-7 days. In the RBDD area, the main source of the catfish’s food consists of the Astacus leptodactylus which it hunts where this specie forms colonies, the crustacean hiding in holes. It also feeds on species of fish, goby and even higher ranked fish which it hunts especially at night. It sucks up the pray creating a certain sound that has inspired different types of bait. It has been found the catfish feeds poorly in winter too. Longevity is of approx. 80 years. The growth rhythm is remarkable:

20-35 cm and 200-500 g and close to 1 kg in the second year. Sport fishing In the RBDD aream the catfish is one of the most preferred specie by sports fishermen. It is caught mainly in the Danube, at stationary fishing, in deep waters, regularly using 80g lead. Nutritions value Catfish meat is very appreciated, having a great taste and lacking small bones. Bigger specimens are very high in fat and muscles, especially in the lower part of the body. It is cooked fresh under all forms.

Spawns can be eaten limited after being cooked in soup. Eel – Anguilla anguilla (Linnaeus, 1758) Spread throughout RBDD Isolated specimens in the Danube and it’s branches Black Sea and the most frequent in Razim – Sinoie and adjacent channels as a result of escape from Babadag lake, where it was grown for over 2 decades. Size Regular 60-100 cm, 1-2 kg Max: 133 cm , 6,6 kg/li> Biology It spends most of its life in fresh, flowing and still waters The time spent in the fresh waters, until reaching sexual maturity which varies as followed: 6-12 for males and 9-20 for females. Maximum reported age: 85 years.

When sexual maturity is reached, eels migrate downstream, reaching seas and the Atlantic Ocean, and from here it travels west 5.000-6.000 km to the Sargas Sea, Bermuda island area where reproduction takes place at about 400 m. Also it is mentioned that this distance takes 6 months to surpass. Reproduction takes place in January – May. After laying their spawns, the reproductives die. After hatching, the larva is transparent. They are transported passively by curents, those reaching salt waters becoming males and those reaching sweet waters becoming mainly females. Near the shores they transform.

At eels of 0,5-1,5kg captured in the RBDD area, the Danube, Babadag lakes and Razim-Sinoie.Fishing for eels is best done at night with either a gaff or a strong line with a small and square bloody piece of red meat.Elvers were once eaten by fishermen as a cheap dish, but environmental changes have lead to increased rarity of the fish. They are now considered a delicacy and are priced at up to £700 per kg in the UK. For Estonia sweet water eels are presented the following information: at the age of 5 – 48,6 cm and 264 g, 7 years 64,3 cm and 592 g, 9 years 74,4 cm and 846 cm, 12 years 81,7 cm and 1086 g, 15 years 89,2 cm and 1348 g. In intensive growth conditions in the first year, the young ones record 50 g and the third year reach 250 g. Thick skin is removed before eating.Eel blood is toxic.

The toxic protein it contains is destroyed by cooking. The toxin derived from eel blood serum was used by Charles Robert Richet in his Nobel winning research which discovered anaphylaxis. It is very apreciated smoked. There are no special protections for the eel. Sterlet – Acipenser ruthenus Linnaeus, 1758 Sprea throughout RBDD until 1968 the sterlet was frequently caught on the Danube branches, especially on Chilia and Saint George. Nowadays, isolated specimens are fished, mostly juveniles. Sporadic catches were recorded in the Razim lake. Size Regular : 50-60 cm, 3-4 kg Max.: 125 cm, 16kg Biology Fresh water specie which prefers deep areas of great rivers with currents and a solid bottom. In can be found in northern Europe in fresh still waters(Lagoda and Onega lakes) as well as in the marine environment (Capsian Sea near great rivers). It only reaches accidentally the Danube and the Black Sea. It winters in groups, in deep holes. Maxim age known is of 24 years.

Sexual maturity installs at 2-5 years for the males and 4-7 for the females at body length of 40-50 cm. Reproduction takes place at a water temperature of 12-17°C (April -May). Food consists of invertebrates especially crustaceans and insect larva. In the lower part of the Danube, the main food element consists of may-fly larva which because of pollution hasn’t been seen for over 45 years. Growth rhythm 26,1 cm at 1 year, 35 cm at 2 years, 40,3 cm at 3 years, 48 cm at 5 years, 53,8 cm at 7 years, 58 cm at 10 years. Industrial fishing: For sterlet fishing are usually used bottom nets. In the past, there were used deep water nets using may-fly nets for bait.

The locals call it “mitilic” ..this no longer exists. Today, the means of cathing are used upstream of the Danube sporadicly. Int the past decade, because of the decrease of stock, it is only accidentaly caught on the 3 Danube branches. Catches on the Danube are a lot more frequent from Isaccea upstream. After 1980, fishing quantities in the mentioned areas are no longer reported but it is estimated at about 500-1000 kg a year.

In certain countries, it is artificially created and called bester, fertile and with a good growing rhythm consisting hope for an offer of sturgeon meat on the market. Sport fishing Int the RBDD area, the sterket does not represent any importance because of it’s rarity. Nutritious value Taste qualities are very appreciated, being known as the tastiest of all sturgeons in the Danube. It has a 6,4% fat content. It is cooked fresh. Spawns are small and gray being less appreciated as caviar than the rest of the sturgeons.

SEVRUGA РAcipenser stellatus Linnaeus, 1758 Spread throughout RBDD Black Sea, Danube, Chilia and Sf̢ntu Gheorghe branches and occasionally in Razim lake. On the Sulina branch does not swim because of intense navigation. Size: Regular 100-120 cm, 6-8 kg Max: 218 cm, 54 kg. Biology Marine specie, migrating. Most of its life is spent on the sea, older specimens in deeper waters at depths of about 10-40m where they find favorable feeding places. For reproduction, it swims to rivers, sometimes at long distances. Maximum mentioned age is of 35 years. Sexual maturity installs at 5-6 years at males and 7-10 years at females, at a body length of 90-120 cm.

As far as migration for reproduction, there are mentioned specimens that enter the Danube in spring, in March-April, at a water temperature of 8-11ºC. Reproduction places form in deep 8-10 meters holes, with bottoms consisting of gravel, sand, away from mud. Today on the Danube, these are situated downstream from Hârşova. A females lays, depending on body measures, 70.300-430.000 spawns. Hatching takes place after 50-100 hours, according to water temperature. After reproduction, adult specimens return to the sea, and the majority of the young ones until autumn, when its length reaches 30-35 cm.

Food consists of invertebrates, and adults feed on fish too. Feeding takes place at night. Growing rhythm recorded: 1 year-30 cm, 2 years-60 cm, 4 years-80 cm, 6 years-110 cm, 10 years-120 cm, 18 years-160 cm. Industrial fishing: Although stocks are falling, it is very big part of the industrial part of fishing being second after beluga. Sports fishing although it feeds in the Danube too, until now, there are no recorded sports catches, at least in the RBDD area. Nutritious value It’s meat is very appreciated, but does not match the taste qualities of the sterlet. It is cooked fresh, salted or smoked.Spawns are small preferred in making caviar.

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