Biological Functions
Upper jaw extends previous eye level, little teeth in jaws and numerous large fangs in front likewise (never more of 18 branched rays). 2 dorsal fins, the very first spiny and separated by a narrow interspace from the second. Young fish have 8-10 indistinct dusky bars on the sides; these are faint in the adult.
Historic Background
The beginnings of pike-perch culture date to the nineteenth century and are linked to carp (Cyprinus carpio) culture in earthen ponds in Central and Eastern Europe. Pike-perch was produced in irrelevant quantities as a so-called extra fish. In the early twentieth century, production started of pike-perch stocking material (summertime and fall fry) in earthen ponds (natural spawning) for stocking open waters. It was produced in monoculture (summertime fry) or in polyculture with carp (fall fry). Pond pike-perch culture likewise started to develop in Western Europe (e.g. France) in the 2nd half of the twentieth century. This kind of pike-perch production has actually been and remains comprehensive in character, and this types has actually been and presently is viewed only as a supplementary fish.

At the beginning of the twenty-first century, the very first aquaculture facilities producing pike-perch in recirculation aquaculture systems (RAS) were developed in Western Europe and, by the close of the first decade, there were less than ten of these centers. Techniques for intensive pike-perch culture remain in the initial stages of advancement but this species is thought about to offer excellent potential customers for European aquaculture.

Main Producer Countries
Currently, the main producing countries are the Czech Republic, Denmark, Hungary, Romania, Tunisia and Ukraine. In addition to the other countries shown on the FAO map, pike-perch are likewise grown in the Netherlands and Poland.
Habitat and Biology
Pike-perch inhabits lakes, rivers, reservoirs and the coastal marine waters (in the catchment areas of the Caspian, Aral, Baltic, Black, and North seas. It is now prevalent in France and western Europe, is quickly extending its range in eastern and central England, and is adjusted to the waters of northern Africa (Algeria, Morocco, Tunisia), North America, and Asia (e.g. China, Kyrgyzstan).

This species typically obtains lengths of 50-70 cm and body weights (BW) of 2-5 kg but an optimum length of 130 cm and weights of 12-18 kg have been reported. Males reach sexual maturity at 2-3 years, women at 3-4 years. Depending on geographical zone, spawning is from April to mid June. Water temperature at spawning initiation ranges from 8.0 to 15.0 ° C. Typically, water depth at natural spawning grounds ranges from 0.5 to 3.0 m. Pike-perch deposit eggs into nests that they have actually built on sand, gravel (favored substrate), or marine greenery. Males actively safeguard nests with eggs for 5-8 days until the larvae hatch. Relative fecundity is 170-230 eggs/g BW. Eggs are little; the size of unhardened and solidified eggs vary from 0.6-1.0 mm and 0.9-1.6 mm respectively. One kg consists of 1.5-2.2 million (unhardened) or 1.0-1.5 million (hardened) eggs. Incubation time is from 3 days (20 ° C) to 11 days (10 ° C) (80-120 ° D). Incubation time for pike-perch eggs (from fertilization to larval hatching) can be determined with the formula: I = 30 124 × T-2,07, where: I– incubation time (h), T– water temperature level ( ° C)

. Larvae are little and devoid of pigment: BW– 0.4-0.5 mg and body length TL– 4.0-5.5 mm. Resorption of yolk sac reserves and lipid bead is finished at TL 5.8-6.5 mm. Scales start being put down at TL 23-28 mm (initially on the caudal peduncle). Pike-perch are considered having three trophic stages: plankton stage up until fish are TL 13-30 mm; combined feed stage (invertebrate animals + fish) up until fish are TL 24-70 mm; and predatory stage (feed made up exclusively of fish) from TL 34-80 mm.

Seed Supply
Spawners are acquired primarily from natural waters. Catches are made in fall (October-November; summer season seine) or spring (March-April; trap equipment, e.g. fyke-nets). Fish caught in the fall are held in earthen ponds. For each 1 kg of spawners there must be 10 m ² of pond bottom and 1.5-3.5 kg of fodder fish. Spawners should be eliminated from the ponds when the mean day-to-day water temperature is 8.0-9.0 ° C and transferred to spawning ponds or hatcheries. A few farms keep broodstocks, normally numbering 50-80 individuals/ha, which are kept in earthen ponds. A few farms produce pike-perch in RAS, and keep spawners in these systems (initial phases of domestication).

Pike-perch do not display unique sexual dimorphism. Males normally display reproducing pigmentation in the pre-spawning duration when they are darker than females. Females have clearly more swollen abdomens. Women with body weights of 1.5-4.0 kg and males of 0.8-2.0 kg are suggested for synthetic spawning. Pike-perch spawners must be transferred in tanks with aeration. If the transport time is les than 2 hours and the water temperature is 8.0-15.0 ° C in 1 m ³ tanks, an optimum of 60 kg of fish can be moved. During transport it is recommended that anti-stress agents such as table salt (5 g NaCl/litre) are used.

Numerous methods of pike-perch recreation are used:

One set of spawners (spawner set– 1? After generating, the fish are left in the pond for 6-8 weeks up until equipping material – summertime fry – has been acquired.
Smaller sized earthen ponds are used (storage or wintering ponds) with surface area areas of roughly 500 to 1 500 m ² and depths of 1.5-2.0 m. Spawning nests (60 × 60 cm) are placed on pond bottoms 3-5 m apart. There must likewise be 10 percent more males than women. Nests with eggs are transported to a hatchery or another pond.
In Finland, cylindrical floating cages with a (diameter 2.0 m; depth 2.0 m) are utilized. The women are injected hormonally, usually with human chorionic gonadotropin (hCG) or carp pituitary extract (CPE). Nests with eggs are moved to ponds or hatcheries.
After being carried to the hatchery, the fish are arranged by sex, and females by their degree of maturity. Adhesiveness is gotten rid of from the eggs by washing them in an aqueous service of tannin at a concentration of 0.5-1.0 g/litre water, bath time 2-5 min. Enzymatic preparations can likewise be used– 0.5 percent aqueous protease option (2 minutes for adhesive removal).
Out-of-season recreation. This is the latest technique, and it is utilized at hatcheries geared up with RAS and cooling systems for lowering water temperatures. Fish are stimulated ecologically (temperature level and photoperiod). Thermal stimulation lasts for 18 weeks– 8 weeks cooling stage (20-8 ° C), 6 weeks chilling phase (8-4-8 ° C), 4 weeks warming stage (8-12 ° C). Photoperiod stimulation is used specifically throughout the warming stage when it is altered from 8L:16 D to 14L:10 D. After this duration, hormone stimulation is used (see above). This allows getting sex products a number of months prior to the natural spawning period.
Hatchery Production
2 types of hatchery production are employed, an extensive/intensive technique and a solely intensive method. Hatchery-reared seed is not typically utilized for producing juveniles to be raised in ponds.

Extensive/intensive technique (ponds? RAS).

Larvae are raised in earthen ponds in which natural or semi-natural pike-perch recreation has previously been conducted. The ideal area of raising ponds for larvae is 0.5-2.0 ha, with a mean depth of 1.2-1.5 m. Organic fertilization is applied – manure (5-8 tonnes/ha). Depending on atmospheric conditions, the fry are gathered 6-8 weeks after the larvae hatch. One ha of pond surface area produces 50-250 kg of summer fry with a mean BW of 0.20 to 0.70 g. In order to harvest the summertime (and fall) fry produced in earthen ponds, it is required to drain the water from the ponds. The fish crowd into harvesting cages positioned behind the outlet box. Fry can likewise be gathered utilizing drifting collecting pens positioned in front of the outlet box. The fry are then carried in plastic bags with oxygenated water (30 litres water + 30 litres oxygen). From 600 to 3 000 summertime fry are equipped per bag, depending upon fish size, water temperature level and transportation time. Oxygenated transportation tanks can handle from 18 000 fry/m ³ (transportation time 15 h, water temperature 20 ° C) to 120 000/m ³ (transport time 2 h, water temperature level 15 ° C).

The fry are equipped into a RAS that comprises circulation tanks with volumes of 1.0-3.0 m ³ (tank depth > 40 cm; optimum 70-100 cm). Light strength measured at the rearing tank surface area need to not surpass 50 lux. The optimal temperature level for rearing fry is 22 ° C. The initial stocking density is 5-8 fry/litre (1.5-3.0 kg/m ³). The fish are fed business salmonid feeds with a high protein content (> 50 percent) and a fat material of 12-18 percent. In the preliminary phase of rearing (adjustment period to new feed) the particle size of the feed is 0.4-0.7 mm. Feed is provided ad libitum for 16-24 h per day. The day-to-day feed ration in the first week is 15-17 percent of biomass. The adjustment duration is 2 to 3 weeks. Survival during this duration is 50-90 percent. Cannibalism is a factor that can limit the efficacy of this approach. The fish must initially be sorted specifically. They are then sorted once again after 3-4 weeks of rearing. Usually, the total length of the hatchery rearing stage is 8-12 weeks.

Intensive approach (RAS).

The techniques utilized for rearing pike-perch larva extremely in RAS is more comparable to those employed for marine than for freshwater species in both character and difficulty. There are 3 critical periods that impact the last success of extreme rearing:.

Larval pike-perch are small and after hatching their alimentary system is an easy, anatomically undifferentiated tube. The stomach and pyloric caecae do not form till about two weeks following hatching (TL 8-13 mm; 210-273 ° D).
Pike-perch are physoclistic (no connection between the alimentary canal and the swim bladder). The short swim bladder inflation period is in between 4-11 days post hatch (DPH) (84-231 ° D).
Duration of magnified cannibalism. The very first cannibals appear very early when the larvae reach TL 10-14 mm (256-322 ° D) and heighten after the fish have actually grown to TL 20 mm.
Larvae are raised in 0.5-1.5 m ³ flow tanks. For the first two weeks, a spray system is used to break the surface tension of the water (this supplies larvae access to climatic air and enables them to fill their swim bladders). Initial equipping density varieties from 20 to 50/litre and the water temperature is 20 ° C. 2 techniques are utilized for the preliminary feeding of larval pike-perch:.

In this technique both commercial feed and Artemia nauplii are fed to the larval pike-perch during the very first 14 days. After 14 days, the larvae are fed industrial feed exclusively. The feed has a high protein content (55-62 percent) and a lipid material of 10-16 percent.
Approach 2. In this approach larval pike-perch are fed salt water shrimp solely for the very first 2 week at a rate of ~ 500 nauplii/fish/day, provided every 1-1.5 h for a minimum of 16 hours daily. After 2 weeks the larvae are trained to accept commercial feed; the duration required to do this is generally 3 days. After 3-4 weeks of rearing (BW > 50 mg) the fish are sorted, and the fish with inflated swim bladders (ISB) are separated from those with non-inflated swim bladders (NSB). This is performed in an aqueous solution of sodium chloride and etomidate at a dosage of 10 g salt and 1 ml of etomidate/litre of water. After the fish have been anaesthetized in this option, the people with ISB rise to the surface, while fish with NSB sink to the bottom. After this procedure, only individuals of great biological quality (ISB individuals) are retained for more rearing.
Raising Fingerlings.
Ponds are equipped with pike-perch spawners (natural or semi-natural pike-perch reproduction), and the hatch is raised for several weeks.

Ponds (0.5– 2.0 ha) may also be equipped with larvae (200 000-500 000/ ha) obtained from hatcheries. 10-14 days prior to equipping larvae the ponds are filled to half their depth (40 percent volume), with the staying water included 10 to 2 week after equipping. The ponds are fertilized with manure at the same time as they are filled with water (4-8 tonnes/ha). Rearing lasts from 6-8 weeks, survival is 15-40 percent, and production is 50-250 kg/ha of juveniles with a mean BW of 0.2-0.7 g.

Nursery.

Nursery rearing in RAS systems.

Juvenile pike-perch (BW 0.2-10 g) are reared in 2-5 m ³ RAS tanks. Water temperature level ranges from 22-24 ° C. The equipping density is restricted to 10/litre. The everyday feed provision is 12-10 percent of biomass. Throughout this stage, stocks are graded every 2 to 4 weeks. Light intensity is minimized from the hatchery level to 20-30 lux at the water surface area. The equipping density (BW > 3 g) is lowered from hatchery levels to 6 individuals/litre. The biomass of the fish observed with BW 3-10 g does not exceed 10 kg/m ³. Juveniles predestined for intensive on-growing are kept until they reach a minimum of 15 g BW. Usually, the nursery stage lasts 8-10 weeks.

Nursery in Ponds.

Polyculture with carp.

Ponds are utilized for less intensive carp production (500-1 000 kg/ha). The ponds are equipped with pike-perch spawners (2 males + 1-1.5 females/ha), fertilized eggs (0.5-1.0 nest/ha), hatched (2 000-10 000/ha) or summer fry (2 000– 5 000/ ha).

Monoculture.

Ponds (0.2-2.0 ha) are equipped with 4 000-6 000/ha summertime fry (BW – 0.2-0.5 g). The ponds are also equipped with fodder fish types (spawners, eggs and hatchlings of roach (Rutilus rutilus), tench (Tinca tinca) and gudgeon (Gobio gobio).

Ongrowing Strategies.
Ongrowing in recirculation systems.

This technique is still under advancement; fewer than 10 facilities in Europe are currently utilizing it. Juveniles of 15-30 g are equipped. In the initial stages (BW 15-100 g), when 2-5 m ³ tanks are utilized, the stock is preserved at 10-30 kg/m ³. Bigger tanks (20-30 m ³ )are utilized for the last, in which the fish are raised to > 1 kg at an optimum equipping density of 80 kg/m ³. The fish are sorted 2 or 3 times, firstly at 100-150 g, secondly at 200-250 g, and thirdly when the fish achieve 500-600 g. Fish of > 1 kg can be acquired after about 15-18 months of on-growing in RAS.

RAS grow-out feeds are high in protein (42-50 percent) and low in lipid (8-14 percent). Feed is delivered using automatic feeders at least three times per day.

The thermal optimum for pike-perch development has to do with 27-28 ° C but quick development rates are already kept in mind at 23 ° C. Oxygen saturation at the inflow is maintained at 100-120 percent, while at the outflow it must not fall listed below 50 percent. pH ought to be 6.5-8.2. Typical levels of total ammonia nitrogen (TAN) and nitrite (NO2-N) determined at the outflow of the raising tanks do not go beyond 0.40 mg TAN/litre and 0.15 mg NO2-N/llitre.

Ongrowing in Ponds.

Pike-perch is raised as a so-called additional fish in polyculture with carp. A minimal stocking rate is typically utilized, particularly 20-100 individuals/ha of fish aged 3+. After 3-4 years, the fish attain body weights of 400-1 000 g and the production of market-sized pike-perch can be as high as 5-50 kg/ha.

Feed Supply.
The pike-perch that are raised in ponds feed on zooplankton, zoobenthos, and fodder fish species.

Those raised in intensive (RAS) culture are fed salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), and sea bass (Dicentrarchus labrax) feeds produced by industrial feed producers. Sinking feed is used, which is provided with automated band feeders either several times daily or continuously. Just recently, 2 or three business feed producers have begun to produce feed particularly developed feed for pike-perch however the nutritional requirements of pike-perch are not well understood; feed formulae are currently being established and improved.

Gathering Strategies.
Market-sized pike-perch and carp raised in earthen grow-out ponds are caught in the fall by draining pipes the ponds. Fish weighing 1-2 kg (usually ~ 1.5 kg) are produced in RAS. Dining establishments choose fish weighing in between 2-4 kg, for which they pay greater costs. Before harvesting, fish are starved for 2-3 days.

Handling and Processing.
Pike-perch are vulnerable to tension and conscious adjustments. The use of anaesthetics is advised, for instance throughout artificial reproduction. After adjustment, such as grading, it is suggested that the fish are bathed in a sodium chloride solution as a stress decrease measure (bath time 1 h in a 0.5-1.0 percent NaCl option).

100 g of skinned fillet of wild-caught pike-perch from natural conditions contains 215 mg of polyunsaturated fatty acids (PUFA), while the PUFA level of pike-perch cultured in RAS is 730 mg. The content of necessary fatty acids – eicosapentaenoic (EPA, 20:5 n-3) and docosahexaenoic (DHA, 20:6 n-3) are 32 and 103 mg in wild-caught pike-perch and 140 and 370 mg in cultured pike-perch respectively.

Production Expenses.
The following contribute to the costs of producing 9-10 g fingerlings in RAS (at first equipped with 0.2-0.5 g summer fry from earthen ponds): labour 40 percent, energy 28 percent, feed 12 percent, fry 20 percent.

Labour costs are 43 percent of the overall expenses, depreciation 12 percent, and feed 7-10 percent. The expense of producing valuable pike-perch (final BW 1.5 kg) is approximated to be USD 6.2-7.0/ kg.