The perch, darters, pike-perches and their relatives comprise a family of mostly freshwater species found across the Northern Hemisphere. There are 10 genera and about 201 species total with about 187 in North America alone (Nelson, 2006). Maximum size approaches 1 m but many species (the darters particularly) are small.

They are characterised by ctenoid scales; a dorsal fin with an anterior spiny portion and a soft rayed posterior portion; an anal fin with 1-2 spines (rather than 3 as in related families) and a few soft rays; pelvic fins thoracic in position, with 1 spine and 5 soft rays; branchiostegal membranes not attached to the isthmus; branchiostegal rays 5-8; teeth on the jaws, vomer and palatines in patches, sometimes with canine teeth; and the operculum has a sharp spine.

Perches are found in warm southern waters to subarctic ones, in both flowing and still water. Some larger species are commercially important while smaller species make attractive aquarium fishes. The small darters of North America rival coral reef fishes for colour when in breeding condition. Perches have a variety of reproductive strategies which include broadcasting, stranding, burying, attaching, clumping and clustering. During the breeding season tubercles develop, particularly on the male. These may be on the body, fins or head and are used to maintain contact and enhance grip between males and females during the spawning act.

Genus Perca
Linnaeus, 1758

This genus comprises 2 species, one found in North American and one in Eurasian, fresh waters.

The body is compressed, scales are small and ctenoid, cheeks and gill covers are scaled, the opercular bone carries a single flat spine, the preopercle is serrated posteriorly and has spikes ventrally, there are no canine teeth, branchiostegal rays 7, the lateral line does not continue onto the caudal fin, and the body usually has strong bars.

Perca fluviatilis
Linnaeus, 1758

Common names

mahi-ye khardar, bacheh suf (= baby suf), mahi suf rudkhanehi Astrakhan (= Astrakhan river suf fish, presumably an old name at this Russian locality), سوف حاجي طرخان (= suf-e Haji Tarkhan meaning Astrakhan suf, an old name no longer in use), suf-e rudkhaneh'i (= river suf), hashtarkhan suf.

[xanibaligi in Azerbaijan; okun' in Russian; perch, European perch, Eurasian perch, river perch].

Systematics

Perca fluviatilis was originally described from Europe.

Collette and Bănărescu (1977) refute earlier workers who maintain that this species and the North American yellow perch (Perca flavescens (Mitchill, 1814)) were the same or at best subspecies, e.g. see Svetovidov and Dorofeeva (1963) and Čihar (1975) for opposing views. Collette and Bănărescu (1977) base their conclusion on the observation that the predorsal bone is anterior to the first neural spine in fluviatilis rather than extending between the first and second neural spines as in flavescens. Other characters also exist to separate the two species. Data on the North American perch cannot therefore be used uncritically as a summary of biology for the Iranian perch.

Key characters

Characters of the genus serve to identify the single, distinctive species.

Morphology

Lateral line scales 40-78; scale rows above lateral line 7-10; rows below lateral line 12-22; and predorsal scales 10-21. Scales have very fine circuli, few anterior radii, a posterior focus and a markedly incised anterior margin where about 5-7 radii terminate. The exposed part of the scale is coarse and is the base for ctenii, best developed on the margin. Dorsal fin spines 12-18; dorsal soft rays 8-17, usually 12-15, after 0-5, usually 2-3 spines; anal fin soft rays 6-11 after 1-3 spines; pectoral rays 9-17; and pelvic rays 4-6, usually 5 after 1 spine. Gill rakers 23-25, reaching between the third and fourth rakers below when appressed usually but variable in length with diet, shortest when feeding on fish, longer when food is zooplankton. The gut is s-shaped with a large anterior loop and there are 3 pyloric caeca. Vertebrae 38-44, and gill rakers 14-29. The chromosome number is 2n=48 (Klinkhardt et al., 1995).

Meristic values for Iranian specimens are:- lateral line scales 59(3), 60(2), 61(2); scale rows above lateral line 9(7); rows below lateral line 17(4), 18(2), 19(1); scales between lateral line and pelvic fin 6(2), 7(5); predorsal scales 10(1), 11(2), 12(1), 13(2), 14(1); and caudal peduncle scales 24(1), 25(1), 26(1), 27(3), 28(1); dorsal fin spines 14(2), 15(1), 16(4); dorsal soft rays 13(2), 14(5) after 2 spines; anal fin soft rays 8(3), 9(3), 10(1) after 2 spines; pectoral rays 11(2), 12(2), 13(3); pelvic rays 5(7) after 1 spine; vertebrae 40(2), 41(3), 42(1).

Sexual dimorphism

Males have longer paired fins than females and are brighter in colour. Females are larger than males of the same age.

Colour

Colour can be affected by diet, especially in the fins which are reddest when feeding on certain crustaceans, and by habitat depth but generally the colour is stable. Fish from along the shore in weedy habitats are greenest, those in open water a pale yellow, and at depth are darker. The body is an overall greenish-yellow with 5-9 black bars on the flanks. The first dorsal fin is grey with black markings on the membranes. The first spine is often black and deep black membranes are evident between spines 1 and 2 and the last 4 to 5 spines. The second dorsal fin is greenish-yellow with melanophores on the rays and membranes, the pectoral fin yellowish and other fins pinkish to yellow to silvery-white. Paired and caudal fins have much sparser melanophores than the second dorsal fin. The lower part of the caudal fin is orange to red. Peritoneum silvery and speckled with melanophores.

Size

Reaches 62 cm and about 10 kg but most are much smaller than this.

Distribution

Found from the British Isles across northern Eurasia to eastern Siberia. Their presence in the Caspian Sea basin of Iran is their most southerly distribution. Also introduced to South Africa, Australia and New Zealand.

In Iran it has been reported from the Anzali Mordab (= Talab) and its outlets, the lower Safid River and the Caspian Sea near Bandar Anzali (Derzhavin, 1934; Holčík and Oláh, 1992; Riazi, 1996; Abbasi et al., 1999; Abdoli, 2000). Jolodar and Abdoli (2004) restrict its presence to the Anzali lagoon and rivers draining into it. Anderson (1880) reports perch to be abundant in the Lar River near Tehran, but this is probably a misunderstanding at this early date.

Zoogeography

Its closest relative is found in North America and they were once thought to be the same species on both continents.

Habitat

Distribution is limited by an inability to survive a temperature of 31°C for more than a few hours, by an inability to tolerate salinities above about 10-12‰ and by avoidance of waters with an oxygen level of less than 3 ml/l. The upper lethal temperature is 33.5°C (Collette et al., 1977). It is not found in the Caspian Sea proper because of the latter limitation. Fresh water is required for spawning. Riazi (1996) reports that this species is native (resident) to the Siah-Keshim Protected Region of the Anzali Mordab and it is also reported from swamps near Hendeh Khaleh in Gilan at about 37°23'N, 49°28'E.

Optimal conditions are large, weed-free, moderately deep, mesotrophic waters with food fish such as Rutilus rutilus readily available. Turbidity is a limiting factor for this species which depends on sight to feed. It is found only in the lower reaches of rivers along the Iranian shore and does not penetrate upstream (Berg, 1948-1949). Nevertheless it can be found in both running and still water and in both small and large water bodies.

Perch are a schooling fish, arranged by size and age. Schools form in the morning and disperse as dusk falls. Schools usually number about 50-200 fish but schools in the thousands are reported. There is a nocturnal resting area and perch move from it to a diurnal active area. The perch may move short distances within a lake and in large water bodies over 90 km but show strong homing tendencies. Seasonal movements are between feeding, spawning and overwintering areas.

Different morphs are found in some areas, depending on habitats: one small, slow- growing, dark and gregarious, feeding on small crustaceans, and found in reed beds, the other large, fast-growing, light and solitary, feeding on fish, and found in open waters.

Populations in the Safid River were supposedly increased after construction of the dam which reduced water flow and raised temperatures.

Age and growth

Maturity in males is usually attained in the second year of life (at only 5-12 cm long) with females maturing 1-2 years later (at 12-18 cm or larger). However some males may mature during their first year or as late as their third. Females grow slightly faster than males after the first 1-2 years. Eutrophication may reduce the age of first maturity because of increased growth rates. Perch in different habitats within the same water body, e.g. weeds beds as opposed to open water, will show different growth rates and body forms. Growth over the whole range of the species varies markedly. Generally fish at age 2 which are greater than 20 cm total length are characterised as having very good growth, moderate growth would be fish at age 3 greater than 16 cm total length while a very poor growth would be evidenced by all fish in the population being less than 16 cm total length. Life span is up to at least 21 years and under artificial conditions up to 27 years, perhaps even 50 years. A maximum age of 11 years is given for a Volga delta population examined by Makarova (1986).

Nezami et al. (2004) found fish in the Amirkelayeh Lagoon on the Caspian coast of Iran were in age groups 1+ to 6+, a total length of 9.5-33.5 cm and a weight of 10.5-350.0 g.

Food

Food for small perch is zooplankton such as rotifers, switching to insect larvae, crustaceans, molluscs and leeches with growth (larger than about 20 mm). Growth is enhanced if fish and crayfish are available. Fish predominate in the diet at a range of sizes between 10 and 25 cm. In the Caspian basin, Rutilus rutilus, Blicca bjoerkna, Pungitius platygaster and gobies (Gobiidae) are eaten (Makarova, 1986). Some slow-growing perch may feed on plankton until 2-3 years old. Cannibalism is common. Maximum feeding levels occur in summer and by autumn has fallen to a maintenance level (Collette et al., 1977; Popova and Sytina, 1977). Feeding is a daylight and highly visual activity. Feeding is more effective in shoals as the perch attempts to seize other fish by the head and, if an individual perch misses, then other members of the shoal have an opportunity to seize the prey. Large perch lie in wait for passing prey items and then dart out to seize them. Unlike northern pike, perch will pursue a prey item if it tries to escape.

In the Amirkelayeh Lagoon diet varied according to age, season and sex, and comprised a wide variety of organisms such as water bugs, odonates, gammarids, plant materials, chironomids, Tinca tinca, hemipterans, Perca fluviatilis, snails, Syngnathus abaster, Gambusia holbrooki, Pungitius platygaster, dipterans, branchiopods, trichopterans, tubifex, frogs and shrimps. The species is an omnivore here and a cannibal.

Reproduction

Spawning occurs in the spring in shallow water, 0.5-3.0 m deep, end of March to early June in the Volga Delta (Makarova, 1986). In Dagestan spawning is from the end of March to the beginning of April and lasts 10-15 days (Shikhshabekov, 1978), elsewhere only 2-3 days. Water temperatures are around 11°C on the Volga (Lönnberg, 1900b) and above 8°C in Dagestan (Shikhshabekov, 1978) but can occur under ice at 4°C. Up to 80% of the spawning population in the Volga Delta is female (Makarova, 1986). There is a spawning migration from deepwater resting areas to shallow spawning areas. Males precede females onto the spawning ground by days or weeks and remain behind after spawning. Brackish-water populations migrate into fresh water. Spawning itself can occur by day or by night.

Although temperature is the major factor affecting the timing of spawning, the occurrence of spring floods is significant in some populations as it gives access to inundation zones of large rivers.

Eggs are twisted around plants, roots and logs in an egg-strand, a cylindrical, hollow, twisted structure up to 3.75 m long, 3.8 cm thick and 8 cm wide. This structure offers protection from predators, fungal infections, desiccation, mechanical damage and smothering in the mud. Egg diameters reach 2.5 mm and fecundity 300,000 eggs. Fecundity increases with age and depends on food supply as in most fish species. As many as 15-25 males queue up to fertilize the egg-strand, following the female as she twists around the logs and plants, rubbing against the plants to void the eggs. The female drives the males away from the egg-strand after fertilisation and may guard the egg-strand for some hours.

Parasites and predators

Sander lucioperca, Esox lucius and Lota lota are predators on perch in the Caspian basin and doubtless other large fishes and birds take this species. Cannibalism begins as early as the fry stage when fish only 2.1 cm long eat smaller fry.

Mokhayer (1976b) records the protozoan Trypanosoma percae from this species in the Caspian Sea basin, the nematode larva Eustrongylides excisus and the annelid Piscicola geometra. Khara et al. (2006a) record the eye fluke Diplostomum spathaceum for this fish in the Amirkalayeh Wetland in Gilan. Sattari et al. (2002) and Sattari (2004) records the presence of the nematode, Eustrongylides excisus. This parasite can damage muscles in commercial species and render them unsuitable for sale. Sattari et al. (2005) surveyed this species in the Anzali and Amirkelayeh wetlands, recording Raphidascaris acus, Eustrongyloides excisus and Camallanus lacustris. Khara and Nezami (2006) examined this species in the Amirkalayeh Wetland and found its diversity of parasites to be less than other predatory species such as Esox lucius. Parasites recorded were Camallanus lacustris, Diplostomum spathaceum, Lemaea sp., Argulus sp., and Dactylogyrus sp. Sattari et al. (2007) record the nematode Eustrongylides excisus and the digenean Diplostomum spathaceum in this species in the Anzali wetland of the Caspian shore.

Economic importance

Holčík and Oláh (1992) report a catch of only 15 kg in the Anzali Mordab in 1990. This species has been studied for aquaculture in Iran.

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in aquaria and aquaculture, as food, in sport, in textbooks, in experiments and because it has been widely introduced outside its natural range. It has been implicated in ichthyootoxism (Coad, 1979b), the symptoms of egg poisoning being summarised under the genus Schizothorax.

Conservation

Illegal fishing and non-standard nets threaten stocks of this species (Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 55, 1997). Kiabi et al. (1999) consider this species to be vulnerable in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, sport fishing, medium numbers, habitat destruction, limited range (less than 25% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin.

Further work

The status of populations of this species in Iran should be carefully monitored in view of the threats outlined above.

Sources

General biology is based on Thorpe (1977) and Craig (1987), and there is extensive European angling literature on this species.

Iranian material: CMNFI 1970-0510, 1, 156.8 mm standard length, Gilan, Golshan River (37º26'N, 49º40'E); CMNFI 1979-0685, 1, 71.5 mm standard length, Gilan, Safid River around Mohsenabad below Dehcha (no other locality data); CMNFI 1980-0123, 1, 68.9 mm standard length, Gilan, Safid River around Dehcha above Mohsenabad (no other locality data); CMNFI 1980-0127, 1, 152.8 mm standard length, Gilan, Caspian Sea near Hasan Kiadeh (37º24'N, 49º58'E); CMNFI 1980-0148, 2, 118.2-142.1 mm standard length, Gilan, Pir Bazar Roga (37º21'N, 49º33'E).

Genus Sander
Oken, 1817

This genus is found in both North America and Eurasia and contains 5 species. There are 3 species in the Caspian Sea basin, 2 of which are reported from Iran. The Shahid Beheshti hatchery on the Safid River breeds the third species, S. volgense (Gmelin, 1789), a northern Caspian Sea species, according to Raymakers (2002) but it is unclear if these have been released and have established populations in the southern Caspian Sea.

The genera Stizostedion Rafinesque, 1820 and Lucioperca Schinz in Cuvier, 1822 are junior synonyms of Sander (see Kottelat, 1997). The pike-perches are elongate and compressed, have large jaws reaching back beyond mid-eye level, canine teeth on the jaws and palatines, the preopercle is serrated posteriorly and has spines ventrally, the opercle has a weak, flat spine at its postero-dorsal corner, cheeks are naked or scaled only dorsally, there are 7-8 branchiostegal rays, adult gill rakers are densely denticulated tubercles, in young denticulated rods, and the lateral line continues onto the caudal fin with accessory lateral lines on the upper and lower caudal lobes. Divergence between North American and Eurasian members of this genus may have occurred in the middle to late Miocene or in the Pliocene (Billington et al., 1990; 1991; Faber and Stepien, 1998).

Sander lucioperca
(Linnaeus, 1758)

Common names

سوف (= suf), سوف معمولي (= suf-e ma'muli or soof-e-maamooli, meaning common suf), sibey(ak) in Gilaki, ? sevideh.

[sif, caysifi or quaysifi in Azerbaijanian; adaty silebalyk in Turkmenian; sudak in Russian; pike-perch, European pikeperch, zander].

Systematics

Perca Lucioperca was originally described from European lakes. This may be the fish referred to as sevideh from the Langarud Mordab by Holmes (1845). However the word may be sepideh which means "the white one" and may in fact refer to Rutilus frisii, the safid mahi.

Key characters This species is separated from S. marinum by the dorsal fins being close together, obviously much less than the eye diameter apart, the anal fin spines are not closely joined to the soft rays, the interorbital width is less than, or equal to, the vertical eye diameter in adults, the upper jaw extends rearwards on a level behind the posterior eye margin in adults (under the rear of the eye in young), there are usually more than 18 soft rays in the dorsal fin, and the spiny dorsal fin bears large spots.

Morphology Lateral line scales 75-150 (this wide range from various literature sources presumably includes counts of scales in the lateral line, and other counts which are of smaller scales to one side of the lateral line; Berg (1948-1949) gives a count of 80-97 for example, which is inherently more reasonable). Scales above the lateral line 12-17 and scales below the lateral line 16-24. Scales are incised on the anterior margin where about 6-9 radii terminate, although not as incised as in Perca fluviatilis. The focus is posterior. Ctenii are well-developed. First dorsal fin spines 11-17; second dorsal spines 1-4 and soft rays 16-27, usually 19-24. Anal fin spines 1-3, soft rays 9-14. Pectoral fin branched rays 11-18 and pelvic fin branched rays 5. Stubby, spinulose gill rakers number 10-17 and vertebrae 40-48, usually 45-48, mode 46. There are 4-9 pyloric caeca. The gut is relatively short but has a long anterior loop. The chromosome number is 2n=48 (Klinkhardt et al., 1995).

Meristic values for Iranian specimens are:- lateral line scales 82(1), 86(1), 89(1), 90(1), 91(3); scales above the lateral line 13(1), 14(4), 15(1); scales below the lateral line 21(2), 22(1), 24(2), 25(1); caudal peduncle scales 33(3), 34(3); first dorsal fin spines 13(3), 14(4); second dorsal soft rays 20(2), 21(2), 22(1), 23(2); anal fin soft rays 11(4), 12(1) 13(2); pectoral fin branched rays 13(2), 14(2), 15(3); pelvic fin branched rays 5(7); and vertebrae 45(3) or 46(3).

Sexual dimorphism

Females have a much lighter, whitish belly than that of males which is marbled blueish in the spawning season. The genital papilla of females protrudes.

Colour The back and flanks are green to blue-grey to brown-black, the belly is white to bluish and fins are yellow-grey. The dorsal and caudal fins have rows of black spots on the membranes, largest and most distinctive on the spiny dorsal fin. Other fins are pale yellow. The eye is silvery because of reflection from the tapetum lucidum. Young have 8-13 brown to blackish-brown bars but these usually fade with maturity. The peritoneum is silvery to brownish in preserved fish.

Size

Up to 1.5 m and 20 kg. The Iranian commercial catch in the 1950s was 24-60 cm long and weighed 1.6-2.7 kg, declining to 0.6 kg (Farid-Pak, no date).

Distribution

Found in the basins of the Baltic, Aegean, Black, Caspian and Aral seas. In Iran reported in the Aras River and along the whole Caspian coastal plain from Astara to the Atrak River as well as in the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea, Gorgan Bay and Anzali Mordab (Nedoshivin and Il'in, 1929; Derzhavin, 1934; Kozhin, 1957; Griffiths et al., 1972; Holčík and Oláh, 1992; Nejatsanatee, 1994; Riazi, 1996; Abbasi et al., 1999; Kiabi et al., 1999; Abdoli, 2000; Jolodar and Abdoli, 2004).

This species has also been stocked in the Zarreinerud, 70 km upstream of Miandoab in 1971 (Griffiths et al. (1972), to Valasht Lake near Marzanabad, Evan Lake northeast of Qazvin, Ghorigol Lake near Tabriz, Marivan Lake in Kordestan and the Haft Barm Lakes west of Shiraz (Anonymous, 1977). Although this species has been introduced to the Manjil Reservoir on the Safid River (Griffiths et al. (1972), this reservoir is drained to remove excess silt and no fishery exists (J. Holčík, pers. comm., 1992). Introductions to reservoirs in Khuzestan did not survive (M. Al-Mukhtar, pers. comm., 1995).

It is also found in the Karakum Canal and Kopetdag Reservoir of Turkmenistan (Sal'nikov, 1995) and may eventually reach the Iranian Tedzhen (= Hari) River basin.

Zoogeography

The relationships of this species are discussed under the genus.

Habitat

Generally this species is found in small schools near sandy and stony bottoms in deeper water of rivers. Ideally there should be some concealment. It can also live in reservoirs. This species has both freshwater and semi-anadromous forms in the Caspian Sea basin. It has a limited migratory behaviour such that morphologically distinct stocks may exist in larger water bodies. The population of the Anzali Mordab represents a separate stock (Hydrorybproject, 1965). Riazi (1996) and Karimpour (1998) report that this species migrates into the Siah-Keshim Protected Region of the Anzali Mordab and is also resident there. Most movements of this species are within 10-20 km although distances up to 300 km have been recorded in the Volga River. Suf show strong homing tendencies. The upper lethal temperature is 35°C. High turbidity levels are preferred. During the day, suf shelter from strong light by descending in the water column (Collette et al., 1977; Marshall, 1977). Knipovich (1921) reports this species from depths of 11.0-11.9 m, possibly deeper, in the Iranian Caspian Sea. In Dagestan this species prefers areas where there is flowing water well-supplied with oxygen (Shikhshabekov, 1978) and avoids vegetation and therefore competition with Esox lucius. Suf will tolerate low salinities and can be found around river mouths in the Caspian Sea basin but the sea itself is too saline.

Age and growth

Males mature at 2-6 years (32 cm) and females at 3-6 years (42-44 cm). Life span may exceed 19 years, although in Lake Eğirdir, Turkey only 7 age groups were recorded (Becer and Ikiz, 1999a). Optimum growth occurs at 28-30°C (Marshall, 1977).

During 1932-1933 in the Anzali Mordab, 5-7 year old fish dominated in catches and weighed 2.6-7.4 kg but by the 1960s this had declined to 2-5 years and 1.6-2.7 kg (Hydrorybproject, 1965). Catches in 1971/72 in the commercial fishery of Iran were 3-7 years old, 33.0-55.0 cm long and weighed 370-2100 g (Razivi et al., 1972). Abdolmalaki (2005) found age groups in the Iranian Caspian to be 2-5 years with 2-3 year olds forming 78.5% of the catch. The von Bertalanffy growth equation was L_t = 52.5*[1-exp-0.158*(t + 1.852)]. The instantaneous rate of total, natural and fishing mortality was 0.95 year^-1, 0.31 year^-1 and 0.64 year^-1 respectively. The calculated exploitation ratio was 0.67, the estimated biomass was 31.56 tons, the minimum sustainable yield was 13.89 tons (lower than the total catch), and the fishery return coefficient was 2.87%. Abdolmalaki and Psuty (2007) report 6 age groups for coastal waters of the southern Caspian Sea, the length-weight relationship was w = -0.020606L^2.85, and the von Bertalanffy parameters were L_∞ = 55.05 cm fork length (substantially less than in the Volga River delta at 79.0 cm and Aras Lake in Iran at 73.3 cm), K = 0.15, t₀ = -2.59 and M = 0.31. More than 90% of the beach-seine caught fish were smaller than the minimum legal length. These authors also provide details of recruitment and fishing mortality for this population which is enhanced by introduction of fingerlings.

Food

The suf is an ambush-pursuit predator. Feeding on fish begins at a length of 5-10 cm (2-3 months of age) depending on the relative abundance of zooplankton, invertebrates and forage fish. In the Volga Delta, spawning Rutilus rutilus in April-May is the most important food, up to 80% of the annual ration. In the 1960s and 1970s when the population of suf was 7 million fish, they ate 53,000 tonnes of Rutilus rutilus (Caspian Sea Biodiversity Database, www.caspianenvironment.org). Adults are solitary but young fish feed in schools on nauplii, copepods and some rotifers. Some adults are cannibals (Collette et al., 1977; Marshall, 1977; Popova and Sytina, 1977) and Balik (1999) reports that in Lake Beyşehir, Turkey, a suf can eat its own species with a mean size of 35.9% of its length. Apparently many prey fish are seized and swallowed tail first. One Iranian specimen contained a Neogobius melanostomus and gobies are an important food item generally in the Caspian Sea, 17.8% of the diet compared to 59.9% for Rutilus rutilus.

Reproduction

The spawning migration begins in late March-early April in Dagestan with spawning in early to mid-April (Shikhshabekov, 1978). In Eğirdir Lake, Turkey spawning took place from April to June and Becer and Ikiz (1999b) give details of fecundity, egg diameters, and the relationships between length, weight and gonad weight and fecundity for fish that mature as young as ages 1-2. The spawning season over the range of this species is late February to late July, usually April-May at 12°C (range 6-22°C) as deep as 17 m. There are distinct spawning stocks.

In the Anzali Mordab, the main spawning area in the southern Caspian, the spawning run usually starts in the first 10 days of March at water temperatures of 8.0-9.5°C, ending at 12-14°C (Hydrorybproject, 1965; Razivi et al., 1972). Apparently, natural spawning has stopped completely in the mordab and this lagoon is stocked with fingerlings from spawners held at Aras, a border reservoir lying between Iran and Azerbaijan (Abdolmalaki and Psuty, 2007). Males build nests in depths of 30 cm to several metres on hard bottoms usually in turbid water. Each nest is a flat pit edged by gravel or shell. Plant roots are often exposed as a spawning substrate on which eggs are laid individually. The nest is guarded by the male and eggs are fanned. The female is driven away after spawning. Male suf are so devoted to protecting the nest that they will remain on site even if water levels fall and their backs stick out of the water. In addition they will try to bite humans if they approach the nest. Spawning is intermittent over several days and usually takes place at dawn. Maximum fecundity is 2.5 million eggs and egg diameters are up to 1.5 mm. Hatching occurs from 4 to 26.5 days, depending on temperature (Collette et al., 1977; Marshall, 1977). Females descend to the sea first from the Anzali Mordab after spawning and fry there are 19-33 mm long by the end of May (Hydrorybproject, 1965).

Parasites and predators

Eslami and Mokhayer (1977) examined 100 specimens of suf and found 20% to be infested with larvae of the nematode Anisakis. Ataee and Eslami (1999, www.mondialvet99.com, downloaded 31 May 2000) report the helminth Anisakis from the gastro-intestinal tract of fish from the Anzali wetland. This parasite can infest man if fish is eaten smoked, salted or fried at temperatures below 50°C. Mokhayer (1976b) records the acanthocephalan Corynosoma caspicum. Jalali and Molnár (1990a) record the monogenean Ancyrocephalus paradoxus from this species in the Safid River. Masoumian et al. (2005) recorded the protozoan parasite Trichodina perforata from this species in the Aras Dam in West Azarbayjan. Pazooki et al. (2007) recorded various parasites from localities in West Azarbayjan Province, including Diplostomum spathaceum and Argulus foliaceus from this species.

The Caspian seal, Pusa caspica, is a significant predator on this species (Krylov, 1984) as are predatory fishes such as Esox lucius, Perca fluviatilis and Silurus glanis. Adult suf have few predators.

Economic importance

There is some opportunity for sport fishing for this species in the Anzali Mordab and potentially in various lakes around the country where it has been introduced (Anonymous, 1977). It is a very popular food fish in Iran (Razivi et al., 1972). It has also been studied in Iran as a control species for undesirable fishes (Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 80, 1997).

Nevraev (1929) reports on catches in various regions of Iran in the early years of the twentieth century. There were no evident trends of increase or decrease. In the Astara region from 1901-1902 to 1913-1914 the catch varied irregularly from 154 to 31,931 fish, in the Anzali region from 1901-1902 to 1918-1919 the catch varied from 608,300 to 3,367,000 fish, in the Safid River region from 1899-1900 to 1917-1918 the catch varied from 9983 to 125,182 fish, and in the Astrabad region from 1900-1901 to 1912-1913 the catch varied from 1400 to 22,900 fish.

Stocks of this species are known to fluctuate in Iran, as obviously do the catch statistics. Most fish are caught in beach seines although some are caught in gillnets, both legally and illegally (see below). The main fishing ground is coastal waters in the Anzali region. Catches in the 1920s were at 3000-4000 tonnes for the coastal zone of the southern Caspian Sea but declined drastically afterward (Razavi, 1999). The commercial catch in Iran from 1956/1957 to 1961/1962 varied from 206 kg to 20,945 kg (Vladykov, 1964; RaLonde and Walczak, 1972), from 1965/66 to 1968/69 it varied from 7 to 77 tonnes (Andersskog, 1970) and from 1963 to 1967 ranged from 0 to 14.6 t (RaLonde and Walczak, 1970b). In the 6 years from 1980 to 1985 catches were recorded by the Food and Agriculture Organization, Rome as respectively 0, 0, 0, 12, 13 and 10 t. Catches in 1990 were about 5-10 t and in 1996 about 35-40 t (Bartley and Rana, 1998b). In 2000-2001, the catch was 18 t or 11% of the total commercial catch in the Iranian Caspian Sea basin. 12 t were caught by beach seine along the coast, 3 t were taken in the Anzali Mordab and the rest was an estimated amount of unlicensed captures (Abdolmalaki, 2005). In 2003-2004 the catch was 38 t, a decrease in comparison to the previous year, with 15 t of this from beach seine cooperatives. Most fish were immature and undersized and the catch was based on release of fingerlings (Abdolmalaki, 2006).

Summaries of catches of this species in the coastal southern Caspian Sea over 8 decadal periods is given in Fisheries. Recent catches from Abdolmalaki and Psuty (2007) are as follows:-

Year	Total catch (t)	Catch by beach seine (t)	Number of beach seine cooperatives	Beach seine efforts (hauls)	Number of illegal gillnets confiscated
1990	4.0	4.0	68	20.975	No data
1991	12.3	12.3	81	27,200	104,828
1992	10.0	8.7	88	30,239	109,446
1993	12.3	7.3	93	33,986	138,026
1994	40.2	22.6	91	27,868	215,381
1995	10.1	4.0	101	34,055	204,831
1996	8.0	2.8	109	42,847	270,727
1997	8.1	2.9	111	45,263	205,999
1998	95.0	54.8	125	52,574	222,897
1999	17.5	11.5	139	50,953	130,849
2000	18.0	12.0	147	56,913	82,678
2001	26.0	21.5	150	60,006	113,729
2002	30.0	20.3	150	57,310	141,506
2003	23.8	15.0	151	53,846	179,656
2004	22.5	14.4	151	49,809	261,875

In the period from 1933/34 to 1961/62 in the Bandar-e Anzali region catches varied from about 3483 t at the earlier date to 33 kg at the later one, with large variations between years. Holčík and Oláh (1992) report a catch of only 22 kg in the Anzali Mordab in 1990, and from 1932-1964 reported catches varied from 1 to 2581 t annually.

Hedayatifard and Jamali (2008) showed that this fish is a good source of polyunsaturated fatty acids and one of the best sources for omega-3 fatty acids, useful in preventing cardiovascular disease.

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in aquaria and aquaculture, as food, in sport, in textbooks, and because it has been widely introduced outside its natural range. The suf or pike-perch is also fish-farmed in Europe for stocking purposes as eggs or young.

Conservation

The decline in catches from about 3000-4000 tonnes to about 30 t noted above has never been adequately explained. Overfishing, degradation of spawning grounds, fluctuating water levels and salinity variations in coastal waters, the volume of freshwater input, oxygen concentrations and input of organic material to estuaries and the sea, are all possible factors (Abdolmalaki and Psuty, 2007). The stocks of this species in Iranian waters also declined in the 1960s (Walczak and RaLonde, 1970; RaLonde and Walczak, 1972). Causes were reduction in estuarine habitat needed for spawning, man-made habitat changes and overfishing of the younger age classes and first year spawners. The catch declined from 125 tonnes annually in the 1940s to 14.6 t in 1967. Vladykov (1964) considered stocks all along the Iranian shore to be at dangerously low levels. Griffiths et al. (1972) suggested that stocks in Iran were on the verge of extinction and recommended a three-year ban on catching this species. Artificial raising of this species is difficult but more than 6 million fingerlings were raised and released into the Anzali Mordab in the Iranian year 1991-1992, a 100% increase over the previous year (Abzeeyan, Tehran, 4(2):VI, 1993). Fingerling production rose from 0.12 million in 1990, to 1.50 million in 1991 and 2.50 million in 1992 (Emadi, 1993a)(note that Matinfar and Nikouyan (1995) give 1.63 and 2.44 million fingerlings for 1991 and 1992). Fingerling production in 1995 was 2.269 million, in 1996 2.4 million and for 1996-1997 8 million (Bartley and Rana, 1998a; 1998b). The Sturgeon International Research Institute, which opened in 1994 near Rasht, released 5-8 million fry in 1996-1997 (Bartley and Rana, 1998b). The release in 1999 numbered 5 million "juveniles" (I.F.R.O. Newsletter, 23:4, 2000). Billard and Cosson (2002) cite an annual production of 5-10 million, mostly released in the Anzali lagoon and Moghaddam (2006) gives a figure of 5.13 million fingerlings for 2002. The highest number of fingerlings released in the Anzali Lagoon was 6,604,000 in 2003 with the lowest being 1,160,000 in 1993 for the period 1991-2003 according to Abdolmalaki and Psuty (2007). The latter authors also note that the beach seines used in Iran (see Fisheries) do not protect young fish. There is a heavy mortality of discarded fish even when legal landing size is enforced and resources are inadequate to manage the fishery effectively. The minimum mesh size of the cod-end of the seines should be increased and its use monitored.

Ramin (1996) has studied semi-artificial propagation and rearing of fry of this species in Iran. Broodstock spawning occurs in March-April at 12-14°C on artificial nests of green wool bunches on wooden frames placed in ponds at 5 m intervals. Nests close to the bottom are preferred and eggs are dropped on them with an average fertilization of 30-90%. The nests with eggs on them are kept in a mist chamber and the eggs collected and placed in jars. Eyed eggs appear on day 3 or 4 of incubation. Yolk-sac absorption lasts 9-13 days and exogenous feeding fry measure 4-6 mm.

Lelek (1987) classifies this species as intermediate to vulnerable in Europe. Kiabi et al. (1999) consider this species to be vulnerable in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, sport fishing, few in numbers, limited range (less than 25% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin. Nezami et al. (2000) consider this species to be endangered because of overfishing, habitat destruction and spawning ground degradation.

Further work

The numbers of this species should be actively surveyed because of threats outlined above.

Sources

Deelder and Willemsen (1964) reviewed the biology of this species as did Craig (1987). Robins (1970) gave a bibliography of the genus Stizostedion (= Sander).

Iranian material: CMNFI 1970-0532, 1, 209.3 mm standard length, Gilan, Caspian Sea near Bandar Anzali (37º28'N, 49º27'E); CMNFI 1979-0431, 2, 211.5-241.0 mm standard length, Mazandaran, Now Shahr fish bazaar (no other locality data); CMNFI 1979-0455, 1, 68.5 mm standard length, Markazi, Manjil Dam (36º45'N, 49º17'E); CMNFI 1980-0127, 1, 266.1 mm standard length, Gilan, Caspian Sea near Hasan Kiadeh (37º24'N, 49º58'E); CMNFI 1980-0130, 1, 197.4 mm standard length, Mazandaran, river near Iz Deh (36º36'N, 52º07'E); CMNFI 1980-0150, 1, 280.8 mm standard length, Gilan, Caspian Sea at Safid River estuary (37º24'N, 49º58'E).

Sander marinus
(Cuvier in Cuvier and Valenciennes, 1828)

Common names

suf-e daryai (= sea suf), souf-e-daryaee.

[daniz sifi in Azerbaijan; morskoi sudak or sea pike-perch, erroneously bërsh by fishermen in the Caspian Sea, both in Russian; sea zander, estuarine perch].

Systematics

Lucioperca marina was originally described from the Black Sea at Feodosiya. No types are known (Eschmeyer et al., 1996).

Key characters

This species is distinguished from S. lucioperca by the dorsal fins being well-separated, but by a distance less than eye diameter, anal fin spines are weak and closely joined to the soft rays, interorbital width in adults is much greater than eye diameter, the upper jaw extends back level with the posterior pupil edge or almost to the posterior eye edge in adults, the dorsal fin soft rays are 18 or less, and the spiny dorsal fin lacks large spots.

Morphology

First dorsal fin spines 12-14, second dorsal fin spines 1-4 followed by 12-18 soft rays, anal fin spines 2-4 followed by 9-12 soft rays, pectoral fin with 1 spine and usually 15 soft rays, and pelvic fin with 1 spine and 5 soft rays. Lateral line scales 75-88, scales above the lateral line 9-13 and caudal peduncle scales 34-36. Scales have few anterior radii, a crenulate anterior margin and a posterior focus. Gill rakers on the upper arch number 12-20, on the lower arch 11-17, reaching the second raker below when appressed, elongate and spinulose. Vertebrae number 38-44. There are 5-7 pyloric caeca. Cheeks are scaleless or almost scaleless. There are canines on the jaws and palatines. These counts are combined for several literature sources and include eastern and western populations of the southern Caspian Sea which show evident differences indicating distinct stocks. The gut is short and s-shaped.

Meristic values for Iranian specimens are:- first dorsal fin spines 13(2) or 14(1), second dorsal fin spines 2 (3), soft rays 16 (3); anal fin spines 2(3), soft rays 12(3); soft pectoral rays 15(3), pelvic fin with 1(3) spine and 5(3) soft rays, lateral line scales 79(2) or 82(1), scales above lateral line 10(1), 12(1) or 13(1), caudal peduncle scales 34(2) or 36(1); and total gill rakers 12(1), 13(1) or 15(1).

Sexual dimorphism

Unknown.

Colour

The back is light grey and the flanks have 12-15 dark bars, which are sometimes indistinct and may be absent, e.g. in females from the eastern Caspian which had small, irregular, dark-brownish speckles. Some fish are almost black and lack bars. The first dorsal fin lacks the strong spots seen in Sander lucioperca and is dark grey to black with patches of concentrated melanophores and clearer areas forming irregular and incomplete stripes, or darkly fringed and with a dark spot at the posterior base. The second dorsal fin and the caudal are finely spotted. Other fins are grey with some melanophores on rays. Eyes are silvery due to the tapetum lucidum. The peritoneum is brownish.

Size

Attains 62 cm (65 cm total length in Jolodar and Abdoli (2004)) and 2.2 kg.

Distribution

Found only in the northwestern Black Sea and the Caspian Sea. Reported from near Gasan-kuli in Turkmenistan (Berg, 1948-1949) and from the southeast Caspian Sea in Iran (Kiabi et al., 1999). Jolodar and Abdoli (2004) record it from the central and southwestern regions of the Caspian Sea including in Astara. An old record is cited below under Habitat.

Zoogeography

The relationships of this species are discussed under the genus.

Habitat

This species lives in the Caspian Sea proper and rarely enters rivers. De Filippi (1865), however, did record "Un molto bello e grosso individuo....in un canale di Murdab, ove l'aqua era del pari sensibilmente dolce". It favours areas with rocky bottoms and does not migrate. In winter, part of the population moves into deeper water at depths of 30 m, rarely 100 m, while another part remains near the shore. The major concentration of this pike-perch is found near the shores of Turkmenistan, and secondly of Azerbaijan.

Age and growth

Sexual maturity is attained at 3-4 years for most fish with a few fish maturing at 2 years (Guseva, 1975). Life span is at least 12 years. Growth is slightly faster in females up to age 5, evens out later and males become larger (Kuliyev, 1981). Males on the spawning grounds average 41.2 cm and females 42.9 cm, with an average weight of 0.94 kg (Berg, 1948-1949).

Food

The principal foods are gobies (Gobiidae), young herring and tyulkas (Clupeidae), silversides (Atherinidae), and crayfish.

Reproduction

The male prepares a nest site and protects the eggs. Spawning takes place at 3-12 m on open, stony bottoms or in "nest-caves" and eggs are laid in a continuous layer. The male constructs and guards the nest. Spawning usually begins in the second half of April and ends in mid-May at temperatures of 10-17°C, and is most intense at 13-15°C (Gusev, 1974a). Up to 126,000 adhesive eggs are laid (Guseva, 1974a; 1975; Kuliyev, 1981) and are larger than in S. lucioperca. Fertilised eggs are 2.6-3.8 mm and at water temperatures of 14.7°C, incubation takes 12-17 days (Gusev, 1974a).

Parasites and predators

None reported from Iran.

Economic importance

The sea pike-perch was commercially fished off the Turkmenistan coast in the 1930s and 1940s with catches of 19 thousand centners (1 centner = 100 kg) or 2,271,000 fish. In 1927-1929 the annual average on the shores of Azerbaijan was 7000 centners and in 1930-1932 10,3000 centners. In 1930 the catch for the whole Caspian Sea was 909 thousand centners (Zenkevitch, 1963). The development of offshore oil deposits has drastically reduced stocks throughout the Caspian Sea (Guseva, 1974b; 1975; Kuliyev, 1981).

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in textbooks.

Conservation

This species has been proposed for inclusion in the "Red Book of the U.S.S.R." which forms the basis for measures to protect species (Pavlov et al., 1985). Kiabi et al. (1999) consider this species to be data deficient in the south Caspian Sea basin according to IUCN criteria. Criteria include possibly few in numbers, limited range (less than 25% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin. The 2000 IUCN Red List lists this species as DD (Data Deficient).

Further work

The distribution and abundance of this species in Iranian waters needs to be examined to determine its conservation status.

Sources

Morphology based in part on Svetovidov and Dorofeeva (1963) and Kuliyev (1981).

Iranian material: CMNFI 1970-0532, 3, 156.3-165.5 mm standard length, Gilan, Caspian Sea near Bandar Anzali (37º28'N, 49º27'E).

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