Species Accounts - Salmonidae

Revised:  04 April 2008

A wide variety of other fishes and birds feed on this species and there have been extensive studies on parasites and diseases of this commercially important species. Akhlagi (1999, www.mondialvet99.com, downloaded 31 May 2000) reports infectious pancreatic and haemotopoitic necrosis in fish from Bovir Ahmadi va Kohkiluyeh Province but not in Fars Province. Liver and intestinal submucosa degeneration and kidney necrosis were observed in diseased fish. Prearo and Ghittino (1993) record a case of lipid liver degeneration in cultured trout. Asadzadeh Mangili (2000) records ichthyobodosis in 3 cm fry from a farm in Bovir Ahmadi va Kohkiluyeh. The mortality rate was 40% and infection rate with Ichthyobodo was 100%. Rainbow trout fed on raw marine fishmeal powder in Fars Province were found to be more exposed to vibiosis (pathogenic Vibrio anguillarum)(Ghazi and Akhlaghi, 1998). Diplostomiasis (infection with Diplostomum spathaceum) is reported from cultured trout in West Azarbayjan (Asadzadeh Manjili and Ghorbanzad, 1999). Zorriehzahra (2002) reports on diseases in farmed fry and Zorriehzahra et al. (2002) record enteric redmouth disease in farmed fish around Tehran. Akhondzadeh Basti and Zahrae Salehi (2003) show that the psychotropic pathogen Listeria monocytogenes is found in market and fish farm samples of this species. Soltani and Rostami (1997) record a mortality level of about 16% for farmed trout in northern Iran infected with a Cytophaga/Flexibacter-like bacterium. Soltani et al. 1999) report a yersinosis-like infection in farmed Iranian rainbow trout. Jalali et al. (2005) summarise the occurrence of Gyrodactylus species in Iran and record G. derjavini from fish in the Sardab-rud. Asadzadeh Mangili (2001) describes gas bubble disease from fish farms in Kermanshah Province. Mortality occurred mostly in fish at 100-200g and symptoms included inappetition, skin darkening, aggregation of fish at inlets and outlets in the ponds, and swimming near the surface. In 20% of the samples, unilateral or bilateral exophthalmia was observed. High day-night fluctuations in the oxygen and carbon dioxide content of the pond water was observed through excessive plant growth. Abdi et al. (2006) recorded the first mortality from acanthocephalosis with Pomphorhynchus laevis in fish farms in Maku, West Azarbayjan.

Economic importance

This species is commercially farmed in Iran for local sale. Experimental studies in the 220 ha "Neur", "Neuer" or "Noor" Lake near Ardabil have shown very good production of this species. A growth rate of 17 lbs (7.72 kg) in 3 years was reported (Anonymous, 1977). A yield of 160 kg/ha was obtained and a catch of 35,000 kg reported (Saadati, 1977) but this was unusual in that there were no other fish and food supplies were extensive. The lake is subject to winter-kill and requires stocking and/or helixers to maintain open water in winter (Bullock, 1971; Nehring, 1973b; 1973c; 1973d; 1974b; 1974c; 1974d; 1974e; 1974f; 1975b; 1975c; 1975d; 1975e; 1975f; 1975g; Nehring et al., 1974; Abbasi, 1974; 1975; Boettcher, 1974a; 1974b; Sanford, 1975; Harrington, 1976).

Kohnehchahry and Heydarpur (1973) outline methods of raising trout using submerged cages which they believe would be suitable for Iranian waters. Cage culture has been tried in Gorgan Bay, the fish escaping during several storms and numbering in the millions (B. Kiabi, pers. comm., 1994; www.ramsar.org/ram_rpt_37e.htm, downloaded 28 July 2000). They have also been cage cultured in Valasht Lake, Mazandaran where 12 cages were expected to produce 22 tonnes of fish (Abzeeyan, Tehran, 5(5):IV, 1994). Nezami et al. (2000) give a total production of fish farms in Gilan, Mazandaran and Golestan provinces (along the Caspian Sea) as 851 t.

The "Kelardasht" or Kalerdasht" Fish Farm (= Shaheed Bahonar Trout Farm of Shilat, the Iranian Fisheries Company, near Kelardasht) has an annual production capacity of 2,500,000 fingerlings of 2 g. Various other fish farms in Iran produce rainbow trout for stocking (Surber, 1969; Krasznai, 1987; Petr, 1987). More recently, Bartley and Rana (1998b) give a figure for the Kelardasht Farm of 3 million fingerlings from a pool of 2000 brood fish at a cost of 600 million rials. White (1988) reported that 60 ha of trout ponds and raceways produced 1000 t a year (see also under Cyprinus carpio). The largest fish farm in Lorestan produced 500 t a year in 2000. Edwards (1989) reported production of 1750 t from 20 licensed farms with a further 1000 t from unlicensed farms. Fingerling "trout" production (probably rainbow trout) in government hatcheries was 0.57 million in 1984, 1.81 million in 1985, 1.57 million in 1986, 3.02 million in 1987, 0.50 million in 1988, 4.23 million in 1989, 4.34 million in 1990, 1.90 million in 1991, and 2.00 million in 1992 (Emadi, 1993a). Fingerling production in 1996 was 6 million (Bartley and Rana, 1998a). Production of this trout increased 27% per year betwen 1991 and 1996, the raceway area for trout increased from 80,000 to 166,000 sq m between 1992 and 1996 and production increased from 775 to 1900 t (Rana and Bartley, 1998a). For comparison, the figures for carps (probably Chinese carps) exceeded 100 million and for mahi safid (Rutilus frisii kutum) it was 145 million. However there are also private commercial hatcheries producing about 750 t of trout each year. The Jajrud Hatchery near Tehran produced 1 million fingerlings as early as 1968 as well as several thousand marketable sized fish (Surber, 1969); and there has been a considerable expansion of hatchery capacity in Iran since that time. Rainbow trout production is only about 5% of total aquaculture production although value per metric tonne is U.S.$14,000 while for carp it is U.S.$10,000. Trout production in Ilam Province was estimated at 3.3 million fish based on 21 farms (Tehran Times, 8 August 2005, downloaded 20 January 2006).

Rana and Bartley (1998a; 1998b) outline trout aquaculture methods and problems in Iran. Most culture of this trout takes place in the Alborz and Zagros mountains which are cooler because of altitude. Farms are small, producing less than 50 tonnes per year. Raceways are used for breeding, rearing of larvae and growing out. Eyed eggs may be imported from Scotland and Norway but this may be banned in future because of disease risks. Increased Iranian expertise and costs may also favour production of eyed eggs in Iran. Survival to the eyed stage attains 80% and to the alevin stage 70%. The private sector produced 10 million fingerlings in 1996. The Manzanarbad Trout Farm near Kelardasht sold 2 million fingerlings in 1997 and produced 25 t for local consumption from 2000 sq m of concrete raceways (Bartley and Rana, 1998b). The Mahi Sera Fish Farm at Karaj produces market sized fish from 20,000 brood stock (Bartley and Rana, 1998b). These are replaced every 2-3 years to maintain growth rates. About 5000 fish are saved each year as next year's brood stock based on size, form and colour. Milt from 4 males is used to fertilise eggs from one female. In 1997, the farm produced 185 t of fish each weighing about 250 g (= 800,000 fish). Sale price is 10,000-12,000 rials/kg. The production cycle is 9-10 months at 13°C.

Trout are fed commercial pellets with a conversion efficiency of 1:1.1-1.4 (wet:dry weight). Growth to marketable size (about 30 cm and at least 225 g) takes 9-14 months depending on temperature (2-13°C) at different localities. Feed deficiencies, poor genetic stocks and low temperatures contribute to slow growth in some farms. Production in raceways is nevertheless about 15kg/cu m, a good efficiency. Cost of fingerlings to grow out farms is 120 rials for a 1 g fry, 250 rials for a 5 g fry and 15 rials/g for heavier fish (Bartley and Rana, 1998b).

There is no consistent monitoring of released fish so the success of stocking is unknown. The Dorudzan Reservoir about 100 km from Shiraz has received 400,000 fry in 1970, 2 million in 1972, 300,000 from Australia in 1974, 100,000 in 1984 and 100,000 in 1985 (Petr, 1987). Experimental fishing in 1976 gave a poor return, perhaps through competition for space with native Capoeta species, heavy poaching during migration into the inflowing river, and lowering of the reservoir level. Eggs are no longer imported and the supplies are spawned in Iran (Emadi, 1993b).

Artificial breeding of this species at the Shahid Motahary Fish Hatchery in Yasuj has been carried out 4-5 months earlier than normal using changes in light regime and hormones. The object of this work was to produce fingerlings throughout the year, increase production and save on production costs (Abzeeyan, Tehran, 7(5):IV, 1996). Dehghani and Akbari (1997) have successfully carried out gonadectomies on this species under field conditions.

A production of 5.5-8.0 tonnes of rainbow trout in rice paddies during winter has been recorded (Iranian Fisheries Research Organization Newsletter, 22:2, 2000). Production in Ilam Province was estimated at to be 3.3 million fish by the end of Iranian year 2005 (http://agriculturenews.faorne.net, downloaded 11 April 2006).

Culture of this species in earthern ponds at Bafgh in Yazd Province used running, saline ground water unsuitable for drinking or agriculture. Production was 2-4 tonnes/ha in 0.40-0.75 ha ponds with salinity at 10-15‰, well water temperature 24ºC reduced to usually less than 20ºC, with a water replacement of 5-10% per day for a period of 5-6 months in autumn and winter. The highest growth performance was from fish fed 35% protein, 430 Kcal/100g energy diet and 20.6% lipid with P/E ratio of 81.4 mg protein/Kcal energy. Aeration had no significant effects on growth (Iranian Fisheries Research Oraganization Newsletter, 25:4, 2000; Ahmadi and Alizadeh, 2004; Bahabadi, 2006). A total of 500,000 fingerlings in fish ponds were released in a two month period in 2005, expected to result in 220 t of product (www.growfish.org/Iranianreport.html). Gonad development was found to be accelerated in brackish water, males maturing two months earlier than in fresh water and ovarian development also being accelerated in Yazd fish (Fahlati Marvast et al., 2003; Fahlati Marvast et al., 2006).

Edwards (1989) gives details on culturing this species and the problems to overcome. Abtahi et al. (2002) found clove oil had no significant difference with MS222, another anaesthetic used in fish farms. Sajedi et al. (2003) have examined mtDNA in Iranian hatchery stocks to measure inter- and intra-populational diversity as an aid in fishery management by selection of the best broodstocks. Studies on the best foods and conditions for this trout in Iran have been undertaken by various authors. Kenari and Mirzakhani (2005) examined the effects of using Artemia urmiana from Lake Urmia (= Orumiyeh) enriched with n-3 HUFA, a fatty acid not present in the brine shrimp, as a larval food. Growth and survival was better than with non-enriched shrimp or with artificial feed. All-female diploid and triploid rainbow trout have been produced in Iran, such trout being unable to reproduce if escaping from fish farms (Johari, 2005). Ahmadi et al. (2005) used the Caspian Sea amphipod, Pontogammarus maeoticus, in rainbow trout food as a means of improving muscle pigmentation, the reddish colour from carotenoids in this dietary item enhancing market value. Carotenoid deposition was higher in males (R. Khodarahami in 5th International Symposium on Sturgeon, Iranian Fisheries Research Organization, 9-13 May 2005, Ramsar). Alavi Yeganeh et al. (2004) studied the use of gammarid powder as a dietary item and its effects in reducing stress in trout larvae, finding a 10% supplement to be effective. Supplementary levels of 2 and 4% of the amphipod were effective in improving flesh colour. Fani (2006a) found fishmeal to have higher digestible and metabolizable energy than soybean meal as feed. Fani (2006b) examined the use of oil by-product from soybeans on weight gain, feed conversion ratio and flesh chemical composition, recommending 10% oil by-product be added to the diet. Shadnoush (2006) showed that corn meal could be used as a nutrient in trout diet, improving weight and length. Kalbassi et al. (2004) induced tetraploidy using heat shock. Johari et al. (2006) investigated production of all-female trout using sex-reversed males and found this to be one of the best methods. Zamani et al. (2006) showed that chromosome manipulation (triploidy) had no effects on digestive enzyme activity.

In addition to these reports, there have been a wide variety of studies in Iran on methods and treatments relevant to culturing rainbow trout, briefly summarised here. Sharifian (1998) studied increases in cortisol hormone levels in trout as a measure of stress caused by handling and induced spawning. Azari Takami et al. (2002) and Dorafshan et al. (2006) examined induction of gynogenesis by UV radiation, Dorafshan et al. (2002) induced spawning by use of a GnRH analogue, Farhangi et al. (2003) on the use of natural zeolites for reducing ammonia toxicity, Bazyar Lakeh et al. (2005) on the effect of dietary astaxanthin on fertilisation rate, Johari et al. (2003) on sperm traits and fertilisation performance of normal males and neomales, Vahdati et al. (2001) on optimal conditions for phagocytic activity of granulocytes, Vahdati et al. (2001) on crowding stress and haematological parameters, Akhlagi (2002) on vaccination against streptococcosis, Yakhchali (2002) on the abundance of the parasite Ichthyophthirius multifilis on coldwater fish farms (which produce trout mostly), Ebrahimi (2004; 2005) on the deleterious effects of copper, cadmium and zinc, pollutants, on sperm anatomy and motility, Zorriehzahra (2006) on fry mortality syndrome from 52 fish farms and hatcheries across Iran, Sheikhi Moghaddam et al. (2004) on the use of alvita (sodium di-acetate) as a fungicide and bactericide, Mirvaghefi et al. (2000) on hydrogen peroxide for fungal control on eggs, Lorestany et al. (2004) on activating solutions and their effects on sperm motility and fertilisation rate, Azari Takami and Meshkini (2006) on the nutritional effects on trout larvae of vitamin C-enriched Artemia urmiana nauplii in relation to growth, survival and environmental stress, Gholipour et al. (2006) found a density of 62 fish per square metre was optimal in concrete ponds for weight gain and feed conversion, Johari and Kalbassi (2006) on alterations in the red blood cells of triploid trout, Mirzakhani and Mahmood Abad (2006) found feeding n-3HUFA enriched Artemia nauplii to larvae increased resistance to environmental stress (pH and temperature), Safari and Boldaji (2006) examined use of canola meal as a partial replacement for fishmeal to reduce cost of diets, Yarahmadi and Moghadasi (2006) on use of decapsulated cysts of Artemia urmiana in the larval diet, Mirzakhani et al. (2006) studied the feeding of n-3HUFA enriched Artemia nauplii as food for larvae used to increase resistance to environmental stress from pH and temperature, Geramy et al. (2007) on photoperiod on growth, survival and feeding parameters in larvae, Rezaei et al. (2007) on bacterial changes and the biogenic amines found in farmed trout stored on ice, Soltani et al. (2007) on vaccination against Streptococcus iniae infection, Yousefian (2008) on genetic parameters of growth, Shafaeipour et al. (2008) on the effects of dietary canola meal on physiology and biochemistry as it can be used to replace substantial levels of fish meal in food, etc.

The Department of the Environment has arranged fishing matches for this trout in the Lar Dam since 1994 (www.iran-doe.org/Special/LAR.htm, downloaded 29 December 2000).

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in aquaculture and aquaria, as food, in sport and in textbooks. Rainbows have been used extensively as research animals as their requirements are well known and they are readily available from hatcheries. Hatchery fish often have reduced or absent fins and deformed mouths. Farmed fish are sold frozen world-wide, the most important trout in this regard. Rainbow trout are one of the top few sport fishes in North America and of great commercial importance because of the money spent on gear, accommodation, transport, etc. by anglers in pursuit of this fish. Many books and articles have been written on the methods and joy of catching this trout. The flesh is excellent eating fresh or smoked and may be red if food is mostly invertebrates or white if food is fishes.

Conservation

Alborz trout have escaped and made their way to the Caspian Sea but the numbers and impact are unknown (Bartley and Rana, 1998b). This species is an exotic and does not need conservation but escapees may affect survival of native species.

Further work

Bartley and Rana (1998b) make various recommendations for the aquaculture of this species in Iran. The establishment of reproducing populations in the wild should be carefully monitored because of the dangers for native species posed by this exotic. Triploid all-female trout should be considered.

Sources

Sources are summaries of biology in North America such as Scott and Crossman (1973). Observed on trout farms in Iran but there is little data on escaped Iranian populations.

Iranian material: no preserved material.

Genus Salmo
Linnaeus, 1758

Members of this genus comprise about 25 nominal species found in North America and Eurasia including the Black, Caspian and Aral seas basins and the upper, and cooler, reaches of neighbouring basins in Iran and Turkey including the Euphrates River, and the Orumiyeh and Namak lakes (Berg, 1948-1949). There is a single described species, native to Iran. These fishes have teeth on the shaft and head of the vomer bone in the roof of the mouth (may be lost with age), the jaw is long, reaching to the posterior eye margin or beyond, scales are small usually more than 100 in the lateral line, colour is pale silvery with dark markings or spottings, anal fin rays (all counted) number 15 or less (16 or more in Oncorhynchus), and there are various unique osteological characters.

These are famous sport fishes and were once caught in commercial quantities. Their biology has been studied extensively and numerous books and papers have been written about them.

Salmo salar
Linnaeus, 1758

Introduced to the Caspian Sea (Mamaev, 2002). No Iranian record.

Salmo trutta
Linnaeus, 1758

Stuffed specimen, Bandar-e Anzali

Liqvan Chay trout, ca, 27.0 cm total length, 4 October 1994, courtesy of Asghar Abdoli

Liqvan Chay trout, ca, 27.0 cm total length, 4 October 1994, courtesy of Asghar Abdoli

Common names

آزاد ماهي (azad mahi or mahi-ye azad = free fish, used in Farsi for trout and salmon), ماهي آزاد (= mahi azad), azad mahi qezelala-ye daryacheh khazar (= Caspian Sea trout), mahi azad Darya-ye Khazar, mahi azad setareh-i Darya-ye Khazar, all for the subspecies caspius; قزل آلا (= gazalala, ghezel ala or kizil ala, meaning red spots), قزل آلاي خال قرمز (= qezelala-ye khalqermez; the Turkic qezel ala is used in Farsi for trout and hence this last means "trout with red spots" although literally it is a tautonym, "red spots with red spots"), mahi azad-ye kezel ala-ye ilbumi (= native salmon trout), qezel ala khalqermez yabumi, qezel ala-ye juibary (= brook trout), all apparently for freshwater residents; mahi azade khal sorkh; qezel ala-ye Liqvanchai (for trout in the Lake Urmia basin).

[gizilxalli or ala-balyk for freshwater residents and gizil balig or kizil-balyk for sea-run fish in Azerbaijanian; Kaspi azatmahysy or kumja in Turkmenian; ala-balukh Armenia; Kaspiiskii losos' or Caspian salmon for sea-run fish, and ruch'evaya forel or brook trout and pestrushka for freshwater residents in Russian; alabalik in Turkish; massialé in Kurdish; brown trout, brook trout, river trout, Caspian trout].

Systematics

Salmo Trutta was originally described from European rivers. Salmo caspius Kessler, 1877 was described from the Bozh'em-Promysl (or Bozhii Promysel) fishing grounds on the Kura River, Azerbaijan with 3 syntypes in the Zoological Institute, St. Petersburg (ZISP). Salmo spurius Pallas, 1814 from the Terek River in the Caspian Sea basin, Russia and Salmo lacustris var. Romanovi Kavraiskii, 1896 from Lake Tabiszchuri in Transcaucasia are usually regarded as synonyms of Salmo trutta. Salmo trutta ezenami Berg, 1948 is a subspecies from Lake Ezenam in Dagestan (ZISP 28356)(Dorofeyeva and Salmanov (2001)) though it may be deserving of species rank (Reshetnikov et al., 1997). Salmo trutta ciscaucasicus Dorofeyeva, 1967 (see also Dorofeyeva (1997) and Dorofeyeva and Salmanov (2001)) is described from the Keyranchay (ZISP 26244) and is found in drainages of the western shore of the Caspian Sea, except for the Kura River and, presumably, excepting Iranian rivers.

The native brown trout (freshwater populations) and Caspian salmon (sea-run populations) of Iran are both usually referred to Salmo trutta caspius Kessler, 1877 in the Caspian Sea and Namak Lake basins (Saadati, 1977). Derzhavin (1929b) examined two small fish from the Karaj River of the Namak Lake basin and recognised them as typical "brook trout" (Salmo trutta). Nümann (1969) considers that southern Alborz trout originate from Caspian stocks. Some authors call the species Salmo fario caspius Kessler, 1877, e.g. Dadikyan (1986). Fricke et al. (2007) regard caspius as a full species.

Tortonese (1954), Kuderskii (1974) and Kottelat (1997) discuss the confused nomenclature of this species. Boulenger (1896), Berg (1948-1949) and Derzhavin (1929b) consider Namak Lake basin trout to be Salmo trutta macrostigma (Dumeril, 1858), originally described from Algeria as a distinct species. The Namak trout were supposedly derived from Mediterranean populations via Persian Gulf drainages but Saadati (1977) dismisses this on the grounds of a close similarity between Namak and Caspian trout and the apparent absence of trout from the Zagros Mountains and Persian Gulf drainages of Iran. Osinov (1988) could not determine a Mediterranean route based on electrophoretic evidence.

In the Lake Orumiyeh basin, apparently restricted to the "Lighvanchai" (probably the Liqvan Chay, the town of Liqvan being at 37°50'N, 46°26'E), is a population of brown trout which has been referred to as a distinct subspecies (Anonymous, 1977). It has not been formally described. Saadati (1977) considers all Iranian trout to be S. t. caspius, with those in the Namak Lake basin being a distinct "race", with some slight differences to typical S. t. caspius (see below), and those trout in the Lake Orumiyeh basin could be a new subspecies.

Earlier authors consider the Caspian basin species to be the same as the Atlantic salmon, Salmo salar Linnaeus, 1758, but blood serum electrophoresis (Ostroumova, 1970) support its position as Salmo trutta as does karyology and osteology (Dorofeyeva, 1965; 1967) and enzyme electrophoresis (Osinov, 1984; 1988). Osinov and Bernatchez (1996) consider trout from the Caspian Sea basin to be part of their "Danubian" grouping, brown trout from the Black, Caspian and Aral sea basins as opposed to an "Atlantic" grouping from the Baltic, Barents and White sea basins (and also a tributary of the upper Volga River in the Caspian Sea basin), based on allozyme and mtDNA studies.

A artificial hybrid of Salmo trutta caspius with Oncorhynchus mykiss is reported on by Pourgholam and Noruzy Moghadam (1996).

Key characters

The dark-spotted back, light halos around some of the dark-coloured flank spots, caudal fin not or only weakly spotted, teeth on the vomer shaft, and only 9-15 total anal fin rays are distinctive.

Morphology

Salmanov (1990) has demonstrated that brook, lake and sea forms of trout from the Caspian Sea basin differ in head and body proportions and in fin shapes although no populations in Iran were considered or given taxonomic status. Osinov (1988) maintains that migratory and non-migratory populations are the same species.

In the Caspian Sea basin dorsal fin with 3-5 unbranched and 7-12 branched rays, anal fin with 2-5 unbranched and 6-10 branched rays, pectoral fin with 10-14 branched rays, and pelvic fin with 6-9 branched rays. Lateral line scales 111-132. Gill rakers 16-23. Pyloric caeca 26-61. Vertebrae 55-61. Scales in lateral series for S. t. caspius 140-160, vertebrae 59-61 (Derzhavin, 1929b; Behnke, 1965). See also below under Zoogeography. The chromosome number is 2n=78-84 (Klinkhardt et al., 1995), 2n=80 (Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 61, 1997; Kalbassi et al., 2006) or 2n=80-82 (Dorofeeva, 1998). The chromosome formula is 14M + 10SM + 56T with NF=104 (Kalbassi et al., 2006).

Meristic values for Iranian specimens are:- dorsal fin branched rays 9(1), 10(5) or 11(1), anal fin branched rays 8(7), pectoral fin branched rays 12(7), pelvic fin branched rays 7(1) or 8(6), and total gill rakers 17(3), 18(3) or 19(1).

The Liqvan Chay fish are similar to S. t. caspius in all except colour, gill rakers being somewhat higher (18-22, mean 20.2) and lateral series scales being higher (132-154, mean 142) but sample sizes were small.

Sexual dimorphism

Abdurakhmanov (1962) reports on two populations form Azerbaijan where he found head length, predorsal distance, snout length and lower jaw length to be greater in males and postorbital length greater in females for both populations, while body depth, dorsal and anal fin heights, and pectoral and pelvic fin lengths are greater in males and eye diameter, pelvic-anal fin distance, head depth and interorbital width are greater in females for one population.

Colour

A specimen from the Anzali Mordab had a dark brown-grey back and top of the head with some round black spots, silvery-yellowish sides with 3-4 longitudinal rows of small red spots with whitish halos, a large black spot on the preoperculum and several smaller spots on the operculum. The belly and lower head surface were white with minute dark melanophores. The dorsal fin was a pale grey with 3-4 horizontal rows of black spots and 1-2 series of 4-8 ellipsoid red spots vertically. The adipose fin was overall yellowish with some grey pigment while the upper half of the fin was more orange in colour. The pectoral, pelvic and anal fins were a pale yellowish or nearly colourless with grey pigment. The anterior 2-3 rays were coloured orange. The caudal fin was greyish with the upper and lower marginal rays dark orange. All fins lacked spots except one red spot observed on the dorsal fin of a larger fish (19.8 cm total length). Smaller fish (13.7-16.2 cm fork length) had 12-14 parr marks. The red flank spots are recognised in the name "kizil ala". Generally in the sea, this species has numerous, dark, x-shaped spots on silvery flanks although some individuals have almost none. The fish caught by Holmes (1845) mentioned below had a dirty olive-green back, dark brown and red spots on the flanks, a roseate tint to the flanks, and a golden belly. The migratory form was dark blue on the back, silvery on the flanks and belly, and had dark spots on the flanks.

Prosek (2003) illustrates in colour a trout from the Tigris River in Turkey, from the Caspian Sea basin in Turkey and Armenia, and from the Liqvan Chay.

The Liqvan Chay population has 54-400 red to orange spots along its flank (compared to only 30-50 generally in European brown trout) giving it a ruby-red sheen (Anonymous, 1977). Only one Liqvan Chay fish had less than 100 red spots based on 13 fish examined by Saadati (1977) compared to a range of 27-134 for 13 S. t. caspius from the Shah Neshin River near Ardabil, where only 2 fish had more than 100 spots. The spotting pattern consists of profuse black and red spots and is distinct from all other Salmo trutta which have fewer and larger spots (Saadati, 1977). Colour photographs, courtesy of Asghar Abdoli of the Agricultural and Natural Resources University, Gorgan, of 3 fish from the Liqvan Chay dated 4 October 1994 with a total length of 27.0 cm showed two fish with about 87 red spots while the other had about 200 (accurate counts not possible because of body curvature and silvery reflections). There was considerable variation in spot size among the three fish, the one with most spots having generally smaller spots which give the sheen referred to above, while the other two fish have more discrete and larger spots. It is unknown whether the Liqvan Chay population has been contaminated with other stocks of Salmo trutta.

Size

The sea-run Caspian salmon attains a larger size than freshwater populations. Attains 51 kg and 1.24 m but most seen in Iran were 10-15 kg (Walczak, 1972). Length reaches 118 cm and weight 21 kg in Iranian samples but such large fish are rare in Iran (Farid Pak, 1968b). Most Iranian catches are 55-105 cm and 1.8-12.7 kg (Farid-Pak, no date). Holmes (1845) reported one fish caught at the mouth of the "Mazzur" River weighing 16 lbs (7.3 kg) and measuring 38.5 inches total length (0.94 m). Nümann (1969) reports fish almost 1 m long in the Karaj Reservoir in 1967. A fish 78 cm long and weighing 8 kg was worthy of note in 1996 (Anonymous, 1996c).

Distribution

The trout is found throughout Europe, in North Africa and east to the Aral Sea basin. It is also recorded from the upper Euphrates basin (Berg, 1949).

The Caspian salmon is found in the Caspian Sea and enters Iranian rivers to spawn as well as being resident in Gilan, Mazandaran and Golestan provinces (Sheil, 1856; Nedoshivin and Il'in, 1929; Kozhin, 1957; Nümann, 1966; R. J. Behnke files; Armantrout, 1980; Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 28, 1996; Abbasi et al., 1999; Abdoli, 2000). Formerly known from the Anzali Mordab and its tributaries (Holčík and Oláh, 1992). Reported prolifically from the Seh Hazar, Chalus and Babul rivers (Fortescue, 1920). Found in the Safid River, Kargan River near Hashtpar, Chalus and Babol rivers. Rare in the Aras (Berg, 1948-1949). Abundant in the upper reaches of the Gorgan (G. S. Karelin cited in Berg (1948-1949) although Karelin only visited the lower Gorgan himself). Reported as S. t. caspius from the Sardab and Tonekabon rivers, Gorgan Bay, the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea and as S. t. fario from the Tajan, Babol, Haraz, Sardab, Tonekabon, Pol-e Rud, and Safid rivers (Kiabi et al., 1999). Jolodar and Abdoli (2004) give its distribution in the Caspian basin as in upstream waters from the Aras to the Tajan, absent in the Atrak and Gorgan rivers.

Also found in the Jajrud (Ouseley, 1819-1823), in the Karaj River (Fortescue, 1924; Derzhavin, 1929b; Berg, 1949), and from the vicinity of Damavand (? Damavand River) (Fraser, 1825), and numerous other localities in the Namak Lake basin (see Armantrout (1980) for localities from the 1970s and Abdoli (2000) for more recent general distributions). However Nümann (1969) seems to indicate that fish in the Karaj River were stocked about 100 years previously from Caspian Sea rivers. Reports from the Zagros Mountains in Iran are uncertain and those from mountains near Kerman even more so! (Walczak, 1972). These last two records have not been confirmed by specimens and with introduction of exotic material may now be impossible to verify. Fraser (1834) reports that "Trouts are found in several of the streams of Azerbijan and Kurdistan". It may be worth noting that Heckel (1843b:995) reports that the collector Theodor Kotschy "did not find trout....in the mountains of Kurdistan. Since we know our collector's diligence, we doubt that trout occurs there" but in (1846-1849a:254) Heckel states "we must add one trout (Salmo), which tastes excellently according to the report presented by our traveller; that trout occurs relatively frequently in the mountains of Kurdistan, but has not been seen by us". This is merely confusing: did Kotschy later find trout or change his account, or did Heckel recall Kotschy's accounts incorrectly?

Brown trout were artificially planted in Gahar Lake of the upper Dez River of the Tigris River basin where viable populations existed in the 1970s in both the upper and lower lake, and more recently (B. Sandford, in litt., 1979; R. Mehrani, pers. comm., 2000). European brown trout were planted in the Caspian Sea and Namak Lake basin and established south of Dorud in the Zagros, and in the Zayandeh River dam but their origin is unknown (Coad and Abdoli, 1993). Trout were also introduced to the Karun River basin and the Zayandeh River Dam (Y. Keivany, in litt., 1992).

Trout are also recorded from the the Lake Orumiyeh basin in the upper Talkheh, Zarreineh and Tatavi rivers (Abdoli, 2000) but whether these are introduced is not certain. The Liqvan Chai in the Lake Orumiyeh basin contains a distinctive trout and Liqvan Chay trout were stocked in the Ab-e Bazuft of the upper Karun River (Tigris River) basin in the autumn of 1975 but this failed (B. Sandford, in litt., 1979; Prosek, 2003).

Zoogeography

The origin of Iranian trout is probably from the north via glacial lakes during the last or earlier ice ages and via the Volga River system or, possibly, from the west via the Black and Mediterranean sea basins (Tortonese, 1954; Nümann, 1969; Kuderskii, 1974; Osinov, 1984; Farid-Pak, 1991). The initial colonisation of the Caspian Sea by this trout apparently occurred much earlier than the late glacial period on electrophoretic evidence (Osinov, 1988). The question of a northern origin remains open however on present biochemical evidence (Osinov and Bernatchez, 1996). The division between their Atlantic and Danubian groupings occurred about 0.5-0.9 million years ago based on their data, perhaps 0.7-2.0 million years ago when the division of European and North American groups of salmonids are taken into account. These authors note that populations within the Caspian Sea basin have unique gene pools, suggestive of reproductive isolation, and these fish are not simply the subspecies S. trutta caspius. Bernatchez (2001) considers all Caspian trout to belong to the Danubian or Ponto-Caspian lineage, one of five lineages, and that the centre of origin was probably from drainages associated with the Cauacasus region of the Black Sea. The major demographic expansion of this lineage probably occurred about 270,000-290,000 years ago. Bernatchez (2001) considers that populations of each sea basin occupied by the Danubian lineage should be recognised as distinct evolutionary lineages but he does not give them names.

Trout in the Zagros Mountains may be Salmo trutta macrostigma (Dumeril, 1858), if this is a valid subspecies, while some authors consider Zagros trout to be S. t. caspius on zoogeographical grounds but pure samples of this population have never been examined systematically (Behnke, 1965). Boulenger (1896) and Berg (1948-1949; 1949) consider trout in the upper Euphrates and in the Namak Lake basin to be S. t. macrostigma. Namak Lake trout are then Pliocene relicts of this Mediterranean subspecies from an invasion via the Persian Gulf region. However, the Namak Lake fishes generally show evident affinities with the Caspian Sea basin ichthyofauna and the trout themselves are very similar in appearance.

The Namak Lake basin trout are generally held in Iran to have been planted by the royal family in the nineteenth century (Saadati, 1977). The royal family had sporting camps on the Lar River and the "Varang-e Rud", a tributary of the Karaj River. Saadati (1977) compares 30 specimens from each of these two localities and found characters to be similar except for pyloric caeca (45-58, mean 51 in the Karaj sample, 35-46, mean 39 in the Lar sample) and in scales in lateral series (131-146, mean 138) and 121-134, mean 127 respectively). He concluded that Karaj River fish are native, of relatively recent origin from the Caspian Sea basin, and only slightly divergent.

Saadati (1977) also reports on a population of trout in the Mordugh Chai (probably Mordaq Chay) in the Lake Orumiyeh basin. This population was typical S. t. caspius with only 17-38 red spots on the flank. It may have been of recent origin via a headwater transfer as the tributaries to the Caspian Sea basin are found nearby. A human agency may have been involved, always a complicating factor in the distribution of fish which are of sporting or commercial interest.

Habitat

Mahi azad live in the Caspian Sea proper and migrate up rivers to spawn. Moosari (1996) describes migration into the Tonekabon River of Iran. Young mahi azad stay in rivers for 2 years. There are also land-locked populations such as that of the Lar River near Damavand Mountain and this species may also be found in cool to cold lakes. Areas with clean gravel are required for reproduction. Temperatures above 15°C cause egg mortality. Adults can survive up to 29°C, 18-24°C is the optimum range and 12.4-17.6°C the preferred range. Atai Mehr et al. (2006) found juveniles to survive salinities of 0 to 12.5 g/l over 120 hours, indicative of their adaptability to changing environments. The best weight and water salinity for release of cultured juveniles was 10 g and 8.0-12.5 g/l.

In the sea, they inhabit coastal areas at 40-50 m with distinct stocks centred on the basins of the major rivers. Migrations occur from Iranian shores to Dagestan (Caspian Sea Biodiversity Database, www.caspianenvironment.org).

Age and growth

The Liqvan Chay population females only begin to mature in their third year and only 50% of males are mature in their second year. This population appears to be in good condition compared to other populations, e.g. in the Lar River, and these figures probably represent more natural values. A population estimate was 1246 fish per km compared to 11,380 per km in part of the Lar River where fish had concentrated to avoid severe drought. The life span in the Lar is 6 years (Nehring, 1975a).

There are stocks of dwarf males in Caspian rivers which do not descend to the sea.

Farid Pak (1968b) found the smallest sexually mature fish in the Caspian Sea was 53 cm long and the largest 105 cm. Most fish in the commercial catch of the Caspian Sea were 5-9 years old in the 1950s (Farid-Pak, no date). Caspian Sea fish may mature as early as 1 year for males under riverine conditions but most fish mature at 3-9 years, depending on the river (Caspian Sea Biodiversity Database, www.caspianenvironment.org). Afraei et al. (2000) examined 190 fish from the Tonekabon River and found age groups 0+ to 4+. Most fish were in the 2+ age group. Maximum size was 175 mm and 84.5 g. Condition factors were 1.268 for males and 1.257 for females. See also below under Reproduction.

Nümann (1969) found Alborz trout to reach 26 cm at the end of 3 years, corresponding to the growth rate for central European fish.

Food

Freshwater populations are known to eat mayfly larvae in Iran as well as other aquatic insects and crustaceans and terrestrial insects taken at the surface. Larger specimens elsewhere are known to take fish and crayfish, and more rarely frogs, salamanders and rodents and this probably occurs in Iran too. Tonekabon River fish (Afraei et al., 2000) fed most intensively in spring and least intensively in autumn. The main prey was Simulium, Plecoptera and Ephemeroptera.

In the sea, young feed on amphipods, mysids and shrimps while adults take common and anchovy kilkas, silversides and shads.

Reproduction

This fish runs up rivers in October-November and March-May in Iran (Roux, 1961b). Holčík and Oláh (1992) record migrations into the Anzali Mordab and a run up the Pasikhan and Siahdarvishan rivers from late September to the end of December. A second run occurred in April-May but was much smaller. Holmes (1845) reports "salmon" in rivers of Gilan from June to the end of October. Bartley and Rana (1998b) report the spawning run on the Tonekabon River to be from September to November and spawning to be from November to December. Spawning occurs on riffles of sand and gravel beds. Spawners are 8-12 years old and are mature at 700 g. About 1500 eggs are produced for each kilogramme of female. The fish examined from the Tonekabon River (Afraei et al., 2000) had an absolute fecundity of 168-379 eggs, average 268 eggs. Maximum egg diameter is 6.1 mm, number of eggs per gram reaches an average of 14.7 and absolute fertility reaches 13,468 eggs in Iranian fish which are considerably smaller than Kura River fish in Azerbaijan (Farid Pak, 1968b).

Alborz trout are ripe at 2-3 years while Caspian Sea fish spend 2-3 years in rivers, then 2 years in the sea before re-entering rivers to spawn at 60-70 cm. Spawning can occur more than once in a life span (Nümann, 1969).

In the Kura River of Azerbaijan there are two races. One enters the river in October and travels no higher than the middle reaches 600-700 km from the mouth, is sexually mature and does not weigh more than 12 kg, and spawns in the same year. The second begins to enter the Kura in October but most fish run in November and December, this race spawns in the upper reaches about one year later (8-11 months) after a long migration of over 1000 km, and attains 51 kg. There are two races also in Iranian rivers (Berg, 1959). The Kura salmon may have up to 45,000 eggs of up to 6.5 mm diameter. Kura salmon spawn only once between ages 5 and 9 years. Some Kura salmon become smolts and migrate to sea in the first year of life but most descend in their second year.

Parasites and predators

Mokhayer (1976b) records the protozoan Trichodina from the gills of trout (? this species) in the Karaj River, the cestodes Eubothrium crassum and E. rugosum, the acanthocephalan Corynosoma caspicum, and the annelid Piscicola geometra. Jalali et al. (2005) and Malmberg et al. (2007) summarise the occurrence of Gyrodactylus species in Iran and record G. derjavini from fish in the Sardab-rud. Sattari et al. (2005) surveyed this species in the Chesli and Khorma rivers, recording Cystidicoloides ephemeridarum.

Economic importance

In a survey of the Lar River in June, RaLonde and Walczak (1970b) found 22 fishermen had caught 222 trout with an average length of 19.85 cm, comparable with an earlier survey by Nümann (1964). The largest fish was 27 cm long. The catch was 2.56 fish per fisherman per hour, a good rate of success (but see older records below). This rate and the production of trout in this river was expected to decline drastically with construction of a dam on the Lar. Sport fishermen took 50,000 trout from the Lar River in 1967 (Surber, 1969). Malek-Eizadi (1993) gives a recent account, in Farsi, of the Lar trout and apparently confirms its decline. Floor (2003) cites older records of fishing in the Lar River.

Azad mahi were caught in weirs and with long, 3-pronged forks year round but the principal seasons were spring and autumn (Holmes, 1845). The catch in the Safid River region was largest from February to April, with a maximum in the middle of March. In 1912-1913, a total of 1180 fish were caught in the Safid River, Anzali and Astara regions. Weights reached 10-12 kg, average 7.5 kg (Nedoshivin and Il'in (1929) cited in Berg (1948-1949)). Fortescue (1920) reported 1500-2500 "salmon" from the Seh Hazar at Shahsevar, averaging 8-10 lbs (3.63-4.54 kg) each and seldom exceeding 18 lbs (8.17 kg). Nevraev (1929) reports on catches in various regions of Iran in the early years of the twentieth century. In the Astara region from 1901-1902 to 1913-1914, the catch ranged in numbers from 236 to 1563 and in the Safid River region from 1916-1917 to 1917-1918 the range was 185-663 fish. Yearly catches of mahi azad in the Anzali region alone have reached as high as 3,037 kg in 1939/1940 and as low as 90 kg in 1946/1947 before commercial fishing was prohibited (Vladykov, 1964; Walczak, 1972). The Food and Agriculture Organization, Rome reported only 1 tonne of "salmonoids" caught in Iran for each of the years 1983 to 1985, presumably the Caspian salmon. Occasional catches are taken in sturgeon nets of fish 1-4 kg in the Anzali region and elsewhere along the Iranian coast (Holčík and Oláh, 1992). Many fish are taken by poachers in traps and nets used to block spawning streams. Salehi (2008) notes a decline in catches of this species from 13 t in 1995 to less than 3 t in 2005 and most of the catch is based on stocking rather than natural reproduction.

There is a state supported stocking programme but growth rate is slow. High summer temperatures (28°C) in the Caspian Sea would affect cage culture and survival (Rana and Bartley, 1998a).

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. Salmo trutta is reported to be ichthyootoxic although there are no reports for Iran or for S. t. caspius (Coad, 1979b; see also under the genus Schizothorax for symptoms of this egg poisoning).

Conservation

Pietro delle Valle, who travelled in Iran from 1616 for 7 years, reported trout from rivulets in Ardabil in the Caspian Sea basin (see Pinkerton, 1758-1826, volume IX:84), a city not now noted for so salubrious an environment for salmonids.

Ouseley (1819-1823) dined while at Tehran on dried and salted azad mahi two feet long (0.61 m) from the Caspian Sea for breakfast one day in November 1811 and on fresh trout (later referred to as "kizl-áleh") from the Jajrud for dinner.

Vigne (1842) recorded catching six or seven dozen a day in the Lar River near Tehran, Charles Murray reported in 1858 that the stream "abounds so much in trout that I frequently kill 50 in an hour with a fly" (recorded in Wright (1977)), Valentine Baker (cited in Prosek (2003)) caught 50-60 trout a day up to 4 lb in weight, and Mounsey (1872) caught 450 fish up to 1.5 lbs (0.68 kg) in 3 days using flies. Anderson (1880) found that the Lar River "abounded in trout". They were still numerous there in the 1970s (Nehring, 1975a). However this population was unusual in that growth rates and population densities fluctuated drastically from year to year, probably because spawning habitat and nursery areas were the only adequate features of this river. Features lacking were feeding areas, stable banks and stream bed, good plant cover along the banks to supplement productivity, good physical and chemical water quality and water levels, and presence of predators as controls on excess reproduction. As a result, recruitment of young-of-the-year was high and led to interspecific competition, earlier sexual maturity, and stunting. Overgrazing in the Lar Protected Area (formerly a National Park) has affected the survival of trout in this region since this reduces the availability of insect food, and in 2000 this situation was exacerbated by the prolonged drought (Imamai, 2000).

Numbers of this species have declined drastically as evidenced by catch records. The catch decreased 100 times since 1959 to the early 1970s and smaller fish taken in beach seines were used by fishermen to eat as their market value was low. In the 1970s, the Shahsavar River was assessed as the best in Iran for this species as the river was in good condition. However, even this river was blocked in at least two areas for capturing fish and almost all adults were taken for "culture" by Shilat. A take of 300 fish provide as many eggs as 20 should because of poor treatment (15°C, Saprolegnia infections). The Anzali Mordab was surveyed half a mile from a guard station and 11 gill nets were found, all illegal, in a half mile stretch in half an hour (Carl Bond Archives, Oregon State University, Corvallis).

Attempts to increase natural reproduction by raising young to a size more likely to survive have been attempted in Iran (Andersskog, 1970). The "Kelardasht" (or Shaeed Bahonar) Fish Farm (part of Shilat, the Iranian Fisheries Company) on the "Sandar" River has a production capacity of 100,000 fingerlings of 15-20 g but this has never been achieved (Woynarovich, 1985; Krasznai, 1987). It takes about 2 years before fingerlings reach 15-20 g and 10-15 cm, large enough to release. Brood stock are collected from the Tonekabon River during the September to November spawning migration. Spawners are 8-12 years old and mature at 700 g. New brood stock are collected each year although stock from previous years are kept as backup. In 1997, 500 fish were caught in a 3:1 ratio of males to females. Eggs from two females are mixed with milt from two males. Egg yield is about 1500 eggs/kg. Growth rate is slow in this species, compounded by low rearing temperatures of 2-17°C. Fingerlings take 10 months to reach 10 g (Bartley and Rana, 1998b). In a study of the Tonekabon River migration pattern, the following conditions are found to be favourable for release of cultured fish: release size should be at least 15 g, release point 500-700 m away from the estuary, release time March and October, and for one-year-old fish smolt release is favoured over parr as the former would migrate to the sea (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 28, 1996). Fingerling production by government hatcheries was 0.01 million in 1986, 0.05 million in 1988, 0.10 million in 1989, 0.16 million in 1990, and 0.20 million in 1991 and in 1992 (Emadi, 1993a). Fingerling production in 1995 was 0.8 million and in 1996 was 0.42 million (Bartley and Rana, 1998a; 1998b). In 2002 and 2003, 344,000 and 325,000 fingerlings were released at a cost of 2125 and 2288 million rials respectively (Salehi, 2008). The "Gharasoo" Research Station in Sari is using cage culture of this species (Madbaygi, 1993b). Smolts weighing 25 g on average were released into cages and fed on locally prepared food (Iranian Fisheries Research and Training Organization Newsletter, 4:5, 1994). Culture of a rapid-growing triploid sea trout has been studied in Iran (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 32, 1996; Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 67, 1997). Sayyad Borani et al. (2006) studied the effects of weight on the osmoregulatory ability of juveniles in an attempt to determine the ideal weight for release (see also above under Habitat). Weight classes were 5, 10, 15 and 20 g and the three larger classes were capable of osmoregulation in Caspian Sea water. Mojazi Amiri et al. (2005) detailed the histology of the digestive tract from hatching to parr stage in order to better understand the digestive system capabilities and enhance rearing. Asaeian et al. (2006) studied brood fish taken from the early mid and late migrations, finding those from the early period were more suitable for offspring production, passing through smoltification more rapidly. However, they noted that fish from all periods should be used to maintain genetic diversity. Sarvi et al. (2006), Hatef et al. (2007), Niksirat et al. (2007) and Sarvi Moghanloo et al. (2007), have studied cryopreservation of sperm, sperm and seminal plasma composition, and in vitro storage of unfertilized ova in Iran as means to help conserve wild populations.

Salehi (2008) carried out a cost factor analysis for fingerling production at the Kelardasht Hatchery in Iran and found labour costs to be 52% and feed 16%. The average cost of production of a fingerling was U.S.$0.84 (6269-7123  rials), more than that for sturgeon (1753-2028) and kutum (54-121). Higher costs are probably associated with lack of broodstock, lower production quantities and the scale of the hatchery. The rate of return at age 3-4 years was estimated at 0.5% of those released annually.

RaLonde and Walczak (1970b) and Walczak (1972) lists the following reasons for decline of this species: lowering of the Caspian Sea level making spawning migrations difficult, habitat changes including siltation, pollution, irrigation dams, and unscreened irrigation intake canals, and poaching. Both adults and freshly released fingerlings are heavily poached (Petr, 1987). In the Lar and Karaj rivers about 1960 professional fishermen took trout using nets, chemicals and explosives until laws regulating seasons and equipment were passed and game wardens hired to enforce them (Surber, 1969). Streams running into the Caspian have their lower 1-3 km dried up by May through irrigation demands and trout are unable to reach the sea. Stronger enforcement of laws by game guards, education of the public, particularly local people, habitat protection and improvement, and a rational exploitation system are required to protect this species. Firouz (1974; 1976) reported that the sea-run form was a major commercial species 25 years prior to his account but the deteriorating environment coupled with dynamiting, netting and trapping severely reduced populations. This fish is now completely absent from the Anzali Mordab (Holčík and Oláh, 1992). Waters where populations survived were designated "Protected Rivers" in an effort to manage this species effectively. There are special licence requirements, bag limits and seasons which anglers must observe. A fine of 10,000 rials is imposed specifically for illegal fishing of this species (Anonymous, 1977-1978).

The Liqvan Chay population has been confined to this single river by, it is believed, destruction of habitat through agriculture and domestication of sheep and goats (Anonymous, 1977). De Mecquenem (1908) said trout were abundant in the upper reaches of rivers in the Lake Orumiyeh basin. In 1975, 500 specimens of this subspecies were transplanted into the Ab-e Bazoft near Shiraz in an effort to conserve it (Anonymous, 1977).

Caspian salmon used to enter the Kura River basin, with 20% running up the Aras River on the Iranian border. Most spawning beds on the Aras became inaccessible in the 1950s with the construction of the Bagramtapinskaya Dam. The Mingechaurskaya Dam on the Kura cut off 80% of that rivers spawning beds in 1951. The former Soviets built salmon hatcheries to offset the losses but these proved to have a low efficiency. The young fish had a high mortality because of release at unsuitable high temperatures, release in poor feeding areas, and exposure to water intakes. In addition, the released fish were too small or too few to undergo significant smoltification and migration to ensure subsequent reproduction. Under natural conditions only a small proportion of juveniles undergo smoltification (Bakshtanskii et al., 1973).

Kiabi et al. (1999) consider S. t. caspius to be critically endangered in the south Caspian Sea basin according to IUCN criteria. Criteria include sport fishing, few in numbers, habitat destruction, medium range (25-75% of water bodies), absent in other water bodies in Iran, and absent outside the Caspian Sea basin. They also consider S. t. fario to be vulnerable in the south Caspian Sea basin according to IUCN criteria. Criteria include sport fishing, medium numbers, habitat destruction, medium range (25-75% of water bodies), present in other water bodies in Iran, and present outside the Caspian Sea basin. Coad (2000a), using 18 criteria, found this species to be one of the top 4 threatened species of freshwater fishes in Iran. Nezami et al. (2000) consider this species to be endangered because of overfishing, habitat destruction and spawning ground degradation. Mostafavi (2007) lists it as vulnerable in the Talar River, Mazandaran. Critically endangered in Turkey (Fricke et al., 2007).

Osinov and Bernatchez (1996) note that populations within the Caspian Sea basin have unique gene pools, suggestive of reproductive isolation, and these fish cannot be managed as a single subspecies, S. trutta caspius. Re-introductions and artificial maintenance of native populations could lead to loss of diversity.

Further work

Togan et al. (1995) show that two Turkish populations of brown trout are genetically distinct, at a level often found between species. Genetical analysis of suspected surviving pure populations of Iranian Salmo trutta should be carried out to determine which stocks should be receive special attention for conservation.

Sources

Iranian material:- CMNFI 1970-0551, 5, 109.9-166.3 mm standard length, Gilan, Ghaleh River near Fowman (37º13'N, 49º19'E); CMNFI 1979-0086, 2, 76.5-145.5 mm standard length, Mazandaran, Hasanabad River tributary to Chalus River (no other locality data); CMNFI 1980-0133, 3, 116.8-139.2 mm standard length, Markazi, Karaj fish hatchery (no other locality data); CMNFI 1980-0158, 1, 93.3 mm standard length, Markazi, Polurd River at Damavand Mountain after Ab-e Ali (35º51'N, 52º04'E); CMNFI 2007-0125, 3, 91.2-169.3 mm standard length, Markazi, Luniz River in Karaj River basin (no other locality data); CMNFI 2007-0126, 7, 95.2-158.3 mm standard length, Azarbayjan-e Khavari, Aldarvish River, Sabalan Mountain (no other locality data); BM(NH) 1877.7.5:1, 7, 168.1-194.7 mm standard length, Tehran (no other locality data); BM(NH) 1908.8.7:27-28, 2, 129.0-145.7 mm standard length, north slope of Elburz Mountains near Tehran (no other locality data).

Genus Salvelinus
Richardson, 1836

The charr genus comprises many species in Europe, northern Asia and North America whose systematics have not been fully worked out. FishBase lists 83 nominal species (August 2007). The charrs have numerous small scales 105 or more in lateral series), teeth on the jaws, palatines and tongue, teeth are present on the head but not the shaft of the vomer bone in the roof of the mouth, scales in the lateral line are smaller than surrounding scales and have little or no overlap with scales before and behind, the body has light pink, red or cream spots, and the lower fins have snow-white leading edges.

Salvelinus fontinalis
(Mitchill, 1814)

Common names

ماهي آزاد چشمه اي (= mahi azad cheshmehi or azad mahi cheshmehi, meaning spring free fish, i.e. spring salmon, free fish being used for salmon and trout species in Farsi), qezel ala-ye juibary (= brook trout).

[brook trout, brook charr, speckled trout].

Systematics

Salmo fontinalis was originally described from the vicinity of New York city.

Key characters

This species is characterised by 109-132 lateral line scales, 8-13 anal fin principal rays, light-coloured spots on the body, teeth on the head of the vomer bone in the roof of the mouth, pectoral, pelvic and anal fins with a white leading edge followed by contrasting black, truncate caudal fin, dorsal and caudal fins have wavy, dark lines and blotches and the back has dark or light green or cream, worm-track markings (vermiculations).

Morphology

Dorsal fin principal rays 9-14, pectoral rays 10-15 and pelvic rays 7-10. Scales are minute, horizontal and irregular ovals with a central focus, few circuli and no radii. The pelvic axillary scale is well-developed. Gill rakers 13-22, reaching the second adjacent raker whem appressed. Pyloric caeca 20-55. The gut is s-shaped. The chromosome number is 2n=84 (Klinkhardt et al., 1995).

Sexual dimorphism

Spawning males develop a hooked lower jaw or kype.

Colour

The back is olive-green to dark brown or blackish fading to a silvery-white belly. Flanks have a red to yellow tint. Flank spots are pale but there are also small, red spots with blue halos. The pectoral, pelvic and anal fins are yellow, orange, or reddish behind the white and black leading edges. Sea-run fish have a blue-green back and silvery flanks with a purplish tinge. Spots are obscured except for the red ones. Brook trout in large lakes are also more silvery than stream resident fish. The jaw tips and the roof of the mouth are blackish. Spawning males are much brighter in overall colour and have an orange-red lower flank and upper belly, bordered below by black on each side which delimits the white belly. Young have 6-12 brown parr marks, the widest equal to eye diameter, and small red, yellow or blue flank spots. The white leading edge to the lower fins is apparent.

Size

Attains a reputed 86.0 cm and 6.6 kg but most are smaller.

Distribution

In North America this species is found from the shores of Hudson Bay and Labrador south in marine waters to Cape Cod in the east and Georgia in the Appalachian Mountains, west through all the Maritime provinces, Québec and Ontario (except the extreme west) to northeast Manitoba. Widely introduced to western Canadian provinces, the U.S.A., South America, Europe, Asia and Australasia.

A private hatchery on the Jajrud imported over 1 million brook trout eggs which were raised to fingerling size only for most to be lost in a flood in 1968. Some were planted in the Jajrud and in the Latian Reservoir in the Namak Lake basin. Survival remains unknown. Also recorded from the Sardab and Chalus rivers of the Caspian Sea basin (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 26, 1996) but this is possibly a misidentification for Oncorhynchus mykiss.

Zoogeography

An exotic species from North America, not closely related to native Iranian salmonids.

Habitat

Brook trout are found in cool waters of streams and lakes, usually less than 20°C, adults preferring 14-16°C. Spawning requires temperatures below 15°C, and below 9°C for optimal hatching. The upper lethal limit is 25°C for adults and 20°C for newly hatched fish. pH range is 4.1-9.5. Pools, underneath banks, under overhanging bushes or behind rocks are favoured spots. During summer months they retreat to deeper water, to about 8 m, in lakes. Some populations run to sea in Hudson Bay and Atlantic Canada. They stay in coastal waters, not moving more than a few kilometres from their natal stream. Populations in the North American Great Lakes live and feed mostly in the lake and run up natal streams to spawn.

Age and growth

Maximum life span is over 20 years but most reach only 5 years in North America. Maturity is attained at 2-3 years, some males at 1 year. Stunting is common in small streams while sea run fish grow faster than freshwater ones. Optimum growth temperatures are 10-19°C.

Food

Food in North America includes aquatic and terrestrial insects, molluscs, various fishes, frogs, and even snakes, mice, voles and shrews. Stream-dwelling fish feed heavily on drifting aquatic organisms during spring run-off but in summer as drift decreases surface insects become important. Most feeding occurs in the early morning and late evening although some food is taken throughout the day. Diet shifts in response to competition with other species. Sea run fish take various marine invertebrates and fishes. Sea run adults in spring and summer eat crustaceans and fish in lower estuarine areas while young are in the upper estuary eating crustaceans and insects. During the fall in the river adults eat little and during winter back in the estuary consumed mostly crustaceans. There is thus a division of food resources between young and adults.

Reproduction

Spawning in North America takes place from August to December, earlier in the north and later in the south. Sea-run charr enter their natal stream in spring and summer even though spawning occurs in fall. Each year they spend 1.5-3 months feeding in the sea. The spawning ground is usually gravelly streams but may be lake shoals if there is some current or spring outflow to keep eggs oxygenated. Spring flows are preferred even in streams. Males arrive on the spawning ground first and defend a territory. Both sexes will rush at other fish entering the redd area. The female cleans a redd of debris by turning on her side and lashing her tail. Redd depth between stones is tested by inserting the anal fin. Redd construction may take up to 2 days with work being carried out both by day and night. Courtship involves gentle pushes, touches and strokes of the female by the male. The female is ready to spawn when she crouches in the redd with her genital area between the stones. The male arches his body and may press the female against the redd bottom, both fish vibrate and eggs and sperm are shed. Accessory or sneaky males may rush in to shed sperm. The female lashes her tail to push eggs into the gravel and then dislodges gravel with her anal fin to cover the eggs to depths as great as 20 cm. Yellow-orange eggs are up to 5.0 mm in diameter and number up to perhaps 17,000 per female although averages range from the low hundreds to a few thousand. Both sexes may spawn again with other fish. The eggs develop over winter, taking 165 days at 2.8°C but only 47 days at 10°C. Temperatures above 11°C will kill the eggs.

Parasites and predators

Brook trout are cannibals on their eggs and young and are eaten themselves by other fishes, water snakes, turtles, various birds and otters.

Economic importance

Brook trout are very popular sport fish in North America caught on lures, live baits and flies. These trout are easier to catch than Salmo trutta and take a wider range of lures. They fight well but are often quite small and do not leap spectacularly like some other members of the salmon family.

The ready availability of this salmonid has made it a useful experimental fish for various physiological, biochemical, toxicological and other studies. Some reared stocks however show deformed or lost fins and distorted mouths.

Conservation

This introduced species is not in need of conservation but in fresh water their preference for cool and clear water makes them susceptible to loss if waters are dammed, channelised and polluted or if banks are eroded deforested and overgrazed, conditions not uncommon in Iran.

Further work

The survival of stocks of this species in Iran should be verified and the effects of this exotic on native species researched.

Sources

Based on general summaries on North American populations such as those in Scott and Crossman (1973) and Becker (1983) as no Iranian material to hand. Iranian populations have not been studied.

Genus Stenodus
Richardson, 1836

The inconnu genus contains a single species found in waters draining to the Arctic Ocean in Eurasia and North America and in the Caspian Sea.

Its characters are essentially those in the species description; a small bone lacking a head canal on the outer side of the lower jaw at the joint of the articular and dentary is distinctive. Branchiostegals number 8-11.

Stenodus leucichthys
(Güldenstaedt, 1772)

Common names

safid mahi (= white fish), آزاد ماهي (azad mahi or free fish), azad mahi Volga (= Volga free fish, or Volga salmon, free fish being used in Farsi for salmon), زيبا (= ziba), mahi-ye ziba or ziba mahi (= beautiful fish, in northwest Gilan, e.g. at Astara), mahi-e-azad-e-ziba, inkonu.

[belorybitsa in Russian; nelma or azatmahy in Turkmenian; inconnu, conny, white salmon, Caspian inconnu].

Systematics

Salmo leucichthys was originally described from the Volga and Ural rivers, Caspian Sea and Kamchatcka, Russia.

The type subspecies in the Caspian Sea basin is the one found in Iran. The subspecies Stenodus leucichthys nelma (Pallas, 1773) of White Sea, Siberian and northwestern North American drainages is more common.

Key characters

The characters of the species are those of the genus.

Morphology

Dorsal fin branched rays 8-13 after 2-6 unbranched rays and anal fin branched rays 9-16 after 2-5 unbranched rays. Lateral line scales 88-121, scales above the lateral line 8-13, and scales below the lateral line 10-12. There is a pelvic axillary scale. Scales bear numerous fine circuli, the focus is slightly subcentral posterior, the anterior scale margin is wavy but irregular in outline and the scale is generally rounded. There are no radii. There is a single flap between the nostrils.Gill rakers number 17-27 and reach the fourth adjacent raker when appressed. Pyloric caeca number 191-193 and the gut is s-shaped. Vertebrae number 64-70.

Sexual dimorphism

Males develop tubercles on the head and sides of the abdomen during spawning.

Colour

Overall colour is silvery without spots.

Size

Reaches 1.5 m and 28 kg, rarely 40 kg. On the coast of Dagestan the average size was 7.6-10.8 kg in the 1920s (Berg, 1948-1949).

Distribution

The subspecies is restricted to the Caspian Sea and its drainage. Rare in Iranian waters with 5 specimens caught and preserved from 5-7 km east of Bandar-e Anzali in the Caspian Sea from 1984-1990. Several dozen fish have been caught each year in Iran, starting in the late 1960s, all from between the mouths of the Safid and Astara rivers (Holčík and Razavi, 1992). Reported from the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea (Kiabi et al., 1999).

Zoogeography

This species is found naturally in the Caspian Sea but was generally believed to inhabit only the northern, and rarely the western, parts to the north of 40°N. Rare specimens were reported by Kazancheev (1981) from the coasts of Dagestan and Azerbaijan in early summer. It probably penetrated into the Caspian Sea from the Arctic Ocean basin during the last glacial period via ponded lakes.

Habitat

Inconnu live in the Caspian Sea proper at depths less than 60-65 m (optimally 25-45 m) and migrate up rivers to spawn, in the Volga for 3000 km. Fat content of fish at Astrakhan at the Volga mouth was 26% of total weight but by the time fish reached the spawning grounds in the Ufa River this had fallen to 14%, and after spawning to 1.5% for females and 1.6% for males. Off Iran they are caught mostly above depths of 25 m from October until the end of December. Some are caught in beach seines in shallow water (Holčík and Razavi, 1992) but elsewhere are known from depths down to 46 m. It is said to move into the central and southern Caspian in summer and returns north when water temperatures fall below 8-10°C in the first half of September (Berg, 1948-1949). This contrasts with the catch records for Iran. Fingerlings tolerate temperatures up to 25ºC in culture ponds but in the sea it is found at temperatures below 20ºC (Caspian Sea Biodiversity Database, www.caspianenvironment.org).

Age and growth

Life span is at least 12 years in the Volga population for females and 8 years for males. Iranian fish were up to 6 years old (Holčík and Razavi, 1992). Spawning females are predominately 6-8 years and males 5-6 years old (Letichevskiy, 1981). Females on the Volga spawning grounds are 85-105 cm, 5.5-9.5 kg while males are 75-100 cm, 3.5-7.5 kg.

Food

There is no feeding on the spawning migration, the fish relying solely on their stored reserves of fat. Fat declined in one study from 21% before, to 2% after, spawning. In the Caspian Sea it feeds on fishes such as gobies (Gobiidae), Rutilus rutilus, Atherina boyeri, young Sander, common and anchovy kilkas, and shads. In the sea, adults feed on kilka and silversides (97-99%)(Caspian Sea Biodiversity Database, www.caspianenvironment.org). Young feed on zooplankton 7-10 days after hatching but are predatory in their second month. Fry descend to the Caspian Sea to feed until they are sexually mature.

Reproduction

Spawning takes place in October and November at 0.2-6.0°C after an ascent up north Caspian rivers. The Volga River run peaks in December and March. Fecundity reaches 390,000 eggs of up to 2.4 mm diameter. Eggs average 26% of the female's weight. The eggs are slightly adhesive and shed on the river bottom. Spawning occurs only once or twice in the life cycle of most fish although exceptional females may spawn 3 times. Spawning occurs at intervals of 2-3 years. Incubation takes 180-200 days and hatching takes place in spring. The young immediately descend to the sea.

Parasites and predators

Eggs are eaten by Gobio species and by Lota lota.

Economic importance

This species has no economic importance in Iran but was a significant member of former Soviet fisheries, taken both in the sea and on its spawning migration. Up to 110,000 fish were taken annually in the Volga-Caspian region. It has a rich, delicate flesh with a fat content of 18-26% and is a favoured smoked product (Caspian Sea Biodiversity Database, www.caspianenvironment.org).

Conservation

This species was listed as threatened in Southwest Asia by Holloway (1976) and endangered in the Caspian Sea by Fricke et al. (2007). Kottelat and Freyhof (2007) state that it is maintained only by stocking and is on the brink of extinction. The population of this species, spawning principally in the Volga, declined drastically after regulation of this river. In the 1960s, the population was estimated to be only 2000 fish but it has recovered to 17,000 fish through artificial rearing (Mina, 1992). In the two decades 1961-1980, fish hatcheries in the Volga Delta raised 72.4 million inconnu. Gravel spawning grounds were also constructed (Letichevskiy, 1981). It 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). Lelek (1987) classified it as endangered. Kiabi et al. (1999) consider this species to be data deficient in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, sport fishing, few in numbers, bodies), limited range (less than 25% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin.

Further work

Further records of this species should be recorded to document the presence and spread of this fish in Iranian waters.

Sources

Morphology based on Holčík and Razavi (1992) for Iranian specimens.

Iranian material: None.

Comparative material: BM(NH) 1878.12.26:23, 1, 199.5 mm standard length, Bremen (no other locality data); BM(NH) 1899.7.25:22, 1, 215.5 mm standard length, Russia, River Obi (no other locality data).

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© Brian W. Coad (www.briancoad.com)