Study on some biological and feeding factors of spined loach Cobitis taenia from the Babolrud, Talar and Siahrud Rivers

Spined loach, Cobitis taenia, is a predominant fish in the river systems of the southern Caspian Sea basin. Although there is evidence of the geographical divergence of this taxon, but no information is available on morphological differences within the species populations. This study was designed to evaluate some biological factors including; morphometric and meristic characters, length-weight, age-growth, condition factor, diet, reproduction, variation and differentiation, in the Babolrud, Talar and Siahrud Rivers in south of the Caspian Sea basin. Age, sex ratio, fecundity, ova diameter and gonadosomatic index were estimated. Also, regression analyses was tested the relation between fecundity and fish length, weight, gonad weight, and also age. Totally 858 fish of which 721 were matures, were collected from these rivers by electrofishing. 37 morphometric characters, 9 meristic characters and 78 truss network system characters were estimated. Resulats of DFA analysis based on data of morphometric and meristic showd that these populations are highly (94.5%) varios from each other. In discriminate function analysis, the proportion of individuals correctly classified into their original groups was 61%, 65.4% and 86.5% for upstream and downstream, respectively. Clustering based on Euclidean distances among groups of centroids using an UPGMA and also principal component analysis’ results for morphometric data indicated that these populations from these three rivers were clearly distinct from each other. Regression equations between length and weight in these three populations were significantly different from Folton factor (b=3), that showed the fish has a negative Alometric growth process. Condition factor was estimated between 0.8912 to 1.2736 and 0.8131 to 1.4489 for males and females, respectively. Sex ratio (female: male) in these populations was 1.2816:1. The difference between the number of females and males was significant and females were more than males. The female and male specimens reach maturity by Tl more than 40 and 30 mm and at the age of 2+ and 1+, respectively. The mean of ova diameter was 0.5824±0.2882. The spawning took place from May to late July, at the water temperature from 18.7 to 24.0°C. The GSI values average at the beginning of the reproduction period was about 9%, with ranged from 2 to 26% in ripe mature females. The absolute and relative fecundity were 2109±792 and 579±208 respectively. The absolute fecundity was significantly related to body weight and gonads weight. Based on the pattern of gonado-somatic index, it was concluded that this fish has prolong active reproductive period, which is a type of adaptation by short-lived small fishes to environmental conditions. The macroscopic and histological results showed that the female and male have 5 and 4 stages in their maturation process, respectively. The RLG index was about 0.4732, which showed the fish is a carnivorous species. Significant difference was observed between fishes with different length and diet. The main foods of the fish were Trichoptera, Chironomidae larvae and Ephemeroptera which were their prefered food as well, however it was estimated that the food selection and diet are affected by environmental conditions

How the body shape changes by the habitat hydrological factors in freshwater benthic fishes; case study on the genera Cobitis (Cobitidae) and Ponticola (Gobiidae)

Benthic fish groups with low mobility are often restricted to a narrow range of a stream course, and their morphological characters tend to be affected substantially by the environmental conditions in their habitat. Due to morphological affectability of fishes by many factors in lotic ecosystems, a landmark-based hypothesis was used to investigate the effects of habitat hydrological conditions on morphological characteristics in freshwater benthic fishes; a case study on the genera Ponticola and Cobitis. A total of 216 gobies and 128 spined loaches specimens were caught from six rivers with different hydrological conditions, along the southern Caspian Sea basin. In discriminant function analysis (DFA), the overall assignment of gobies and loaches into their original groups were 95.7% and 80.5%, respectively. Discriminant analysis for pairwise groups shows a longer snout, shallow body/head, and elongated body for populations living in the large slope channel with faster water velocity versus relatively short snout and deep body/head for those living in small slope channel with slower water velocity. The results confirm the possibility of changes in the morphological characters of the benthic gobies and loaches, which should be considered in taxonomical and biological studies

Forecasting habitat changes of Vimba persa (Pallas, 1814) under climate change using machine learning techniques in the southern Caspian Sea basin

The global climate change will decrease species distribution, loss of biodiversity, and decreased food security. The main purpose of this study was to forecast the distribution of Vimba persa in the southern Caspian Sea basin under two optimistic and pessimistic scenarios in 2050 and 2080 by the MaxEnt model in R software. Five environmental variables ?were used for the modeling: annual ?mean temperature, annual temperature range, annual ?precipitation, flow accumulation, and slope. The results demonstrated that the model's performance in predicting species distribution was "Good" (0.862) based on the Area Under the Curve criterion. The annual temperature range variable had the greatest impact (61.5) on determining the distribution of the studied species among the environmental variables used in modeling. Moreover, the results indicate that the distribution range of the Caspian vimba is likely to be reduced in 2050 and 2080 under both optimistic and pessimistic climate change scenarios. Hence, the decreasing distribution of this fish, an economic species interested in sport fishing, poses a serious threat to food security and livelihoods for local communities. In conclusion, policymakers should focus on increasing public awareness, implementing correct management practices, taking preventive measures, developing protection plans, allocating more funds for reconstruction and the restoration of aquatic ecosystems, and trying to reduce the accelerating factors of climate change

How the selective breeding in aquaculture programs can change the body shape of cyprinids; a case study on the native Cyprinus carpio and a cultured stock

Decades since restocking program of the vulnerable native Cyprinus carpio in the southern Caspian Sea, the cultured stocks in hatcheries have created new challenge to protect the native population. Releasing the cultured common carp in natural water-bodies caused an uncertainty about originality of the carp broodstocks within the restocking program. To clarify that how the selective breeding with aquaculture purpose could change the body shape with aiming to prepare an identification key for the indigenous and cultured stocks, a landmark based morphological characteristics of these stocks from the Anzali Wetland and a hatchery were analyzed. Univariate analysis of variance of 100 adult specimens collected during the non-reproductive season were observed in 62 morphometric characters out of 78 (P<0.05). Principle component analyze (PCA) of morphometric characteristic showed a high differentiation between these stocks. In morphometric traits, linear discriminate function analysis (DFA), the overall assignments of individuals into their original groups between stocks were 100%. The PCA and DFA showed a morphological segregation of the studied stocks based on the characters head shape, pre-dorsal, pre-pelvic and pre-anal distances, caudal peduncle depth, dorsal fin and ventral fin origins, body depth and caudal fin origin. The results showed stocks represent two distinct morphological forms of C. carpio that had high morphometric differentiation. The results can be useful as baseline information on the native stock for conservational policy. To protect the vulnerable population, using wild native broodstocks in the restocking program is strongly recommended

How did dams affect length-weight and length-length relationships of Capoeta razii (Cyprinidae) in Sefid River, the southern Caspian Sea basin?

Fish populations are affected by dams in terms of morphology, reproduction, migration, growth rate and etc. To examine the hypothesis; how dams can affect the length-weight and length-length relationships in cyprinids, four Capoeta razii segregated populations (by dams) were studied. The length-weight (LWR) and length-length (LLRs) relationships were calculated for three populations from upstream, dam lakes and downstream of Manjil and Tarik dams in Sefid River, in the southern Caspian Sea basin. Also, one independent population from the damming impacts was considered as the control, to examine other possible annual effects on LWR. The b values in the LWR ranged from 2.893 to 3.586 in downstream and dam lakes populations, respectively. The r2 value ranged from 0.966 to 0.988. The averages of recorded length and weight in dam lake population were up to two and six times (respectively) more than the ranges in up and downstream populations. Monthly LWR is presented for the control population. The sex and maturity were found as effective factors on LWR in the control population. No significant differences were observed in LWR by seasons. All LLRs were highly significant (r2> 0.95). This study presents that the dams and the sex and maturity can be considered as effective non-biological and biological factors (respectively) affecting growth patterns as expressed by length and weight relationships in cyprinid (C. razii) populations. The results may be helpful in future fisheries studies and conservation programs

Morphological variation of shad fish Alosa brashnicowi (Teleostei, Clupeidae) populations along the southern Caspian Sea coasts, using a truss system

A 15-landmark morphometric truss network system was used to investigate the hypothesis of population fragmentation of Shad fish Alosa braschnicowi Borodin, 1904 along the southern Caspian Sea. A total of 181 A. braschnicowi specimens were caught from six localities, respectively from the west to the east including; Astara, Rezvanshahr, Anzali, Tonekabon, Sari and Miankale. Principal component analysis, canonical variates analysis and clustering analysis were used to examine morphological differences. Univariate analysis of variance showed significant differences between the means of the six groups for 72 standardized morphometric measurements out of 105 characters studied. In canonical variates analysis, the overall assignment of individuals into their original groups was 71.46% and scatter plot of individual component scores between CV1 and CV2 showed fish specimens grouped into six areas. Clustering analysis based on Euclidean square distances among groups of centroids using UPGMA resulted into six main clusters indicating morphologically distinction populations of A. braschnicowi in the region. These populations of A. braschnicowi are distinguished especially by head shape, eye diameter, and pre-dorsal, pre-pelvic and pre-anal distances. Therefore, it is suggested considering these morphologically different populations as distinct stock in the southern Caspian Sea coasts

Description of skeletal structure and cranial myology of Cobitis keyvani (Cypriniformes: Cobitidae)

Cobitis keyvani is recently described from the sourhern Caspian Sea basin. Limited information is available about morphological features of C. keyvani, therefore this study was conducted to provide osteological characteristics and cranial myology of this species. For this purpose, nine specimens of C. keyvani were collected from the Talar River. The specimens were cleared and stained with alizarin red S and alcian blue for osteological examinations. The detailed skeletal structure and cranial muscles of C. keyvani were provided. Based on the results, C. keyvani can be distinguished from other members of the genus Cobitis by a contact between sphenotic and supraoccipital and a contact between pterosphenoid, parasphenoid, prootic and sphenotic in terms of osteological features

PRVI NALAZ O POJAVI PARAZITA Neoechinorhynchus rutili KOD PORODICE Cobitis faridpaki (Cobitidae) U JUŽNOM DIJELU KASPIJSKOG JEZERA

Members of the Cobitidae family are not economically important, thus few studies have been made on their parasitology and there is not a single report on their parasites in Iran. In the present study, a total of 225 individuals of Cobitis faridpaki were collected from the Babolrud River around the southeast of the Caspian Sea basin (Mazandaran province, north of Iran) on 12 separate occasions between May 2009 and April 2010. After recording biometric characteristics, common necropsy and parasitology methods were used. In this study, a total of 193 individuals of an acanthocephalan parasite, Neoechinorhynchus rutili were found in C. faridpaki. The prevalence, mean intensity of infection ± standard deviation (SD), range and mean abundance ± SD of the parasite are as follows, respectively: 63.11, 1.36±0.61, 1-4 and 0.86±0.82. The prevalence, mean intensity of infection and abundance of N. rutili were significantly different in various age classes, but it was not the case for different seasons and the sexes. The occurrence of N. rutili is reported for the first time from C. faridpaki in Iran.Vrste iz porodice Cobitidae nisu gospodarski važne, o čemu svjedoči tek nekolicina studija o njihovoj parazitologiji i nedostatak bilo kakvog izvješća o njihovim parazitima u Iranu. U ovom je istraživanju prikupljeno ukupno 225 jedinki Cobitis faridpaki iz rijeke Babolrud u jugoistočnom dijelu Kaspijskog jezera (pokrajina Mazandaran u sjevernom Iranu) tijekom 12 navrata od svibnja 2009. do travnja 2010. godine. Nakon bilježenja biometrijskih karakteristika, primijenjene su uobičajene metode autopsije i parazitologije. U ovom je istraživanju pronađeno ukupno 193 primjeraka parazita akantocefala (Neoechinorhynchus rutili) kod vrste C. faridpaki. Učestalost, srednji intenzitet zaraze ± standardno odstupanje (SD), raspon i srednja brojnost ± SD su iznosili 63,11, 1,36±0,61, 1-4, odnosno 0,86±0,82. Učestalost, srednji intenzitet zaraze i brojnost N. rutili bili su znatno drugačiji u različitim dobnim skupinama, ali ne i za različita doba godine i spolove. Pojava N. rutili prvi put je zabilježena kod vrste C. faridpaki u Iranu

First record of the loach fish Paracobitis cf. malapterura in the Kavir basin, northern Iran

The loach fish Paracobitis cf. malapterura Valenciennes, 1846 (Nemacheilidae), formerly believed to be an endemic species in the Caspian Sea basin, was recorded for the first time in the upper Kavir basin. This extension of its recorded range makes it likely that it has been overlooked in other parts of the Kavir basin