Mitochondrial DNA variation in natural populations of endangered Indian Feather-Back Fish, Chitala chitala

Genetic variation at mitochondrial cytochrome b (cyt b) and D-loop region reveals the evidence of population sub-structuring in Indian populations of highly endangered primitive feather-back fish Chitala chitala. Samples collected through commercial catches from eight riverine populations from different geographical locations of India were analyzed for cyt b region (307 bp) and D-loop region (636–716 bp). The sequences of the both the mitochondrial regions revealed high haplotype diversity and low nucleotide diversity. The patterns of genetic diversity, haplotypes networks clearly indicated two distinct mitochondrial lineages and mismatch distribution strongly suggest a historical influence on the genetic structure of C. chitala populations. The baseline information on genetic variation and the evidence of population sub-structuring generated from this study would be useful for planning effective strategies for conservation and rehabilitation of this highly endangered species.     

Conservation of freshwater fish resources of India: new approaches, assessment and challenges

The freshwater resources of India are currently experiencing an alarming decline in fish biodiversity due to several factors and as a result, a sizeable portion of fresh water fishes have been categorized as threatened. This emphasizes an immediate need for initiating research and actions for alternative management techniques to protect these aquatic systems. One such option that has potential to protect freshwater ecosystem from numerous threats is the creation of freshwater aquatic sanctuary (FAS) within protected area network. Though similar conservation practices are well established in the terrestrial and marine ecosystem, however, the work on freshwater systems has been very slow and negligible. In the present communication we conceptualized the need and approach for developing FAS within the protected area network based on our observations in the water bodies of the selected wildlife sanctuaries in Northern India as well as success stories of some other countries. In this study we assessed the fish diversity in the selected protected areas of Northern India. The assessment indicated that these sanctuaries harbor 28.26–31.13% of freshwater fishes, which are threatened in other areas. Apart from Indian Major Carps, Tor putitora, Chitala chitala, Pangasius pangasius, Clupisoma gerua, Ailia coila, Aorichthys aor, Wallago attu, Rhinomugil corsula, Ompok pabda, Ombok pabo etc. were the important species encountered in the protected waters. The various issues related to FAS including objectives, approach, potential tools, implementation and management are discussed towards saving endangered fish germplasm resources. Approaches, tools and modus operandi proposed in this communication could be utilized by other developing countries in the region.     

Length–weight relationships and condition factor of the Japanese silver-biddy, Gerres equulus, in the Yatsushiro Sea, western Kyushu, Japan

The Japanese silver-biddy Gerres equulus (Temminck and Schlegel) is one of the most common shore fishes in the costal waters of southern Japan and commercially important for the local fishery. In this study the condition factor, length–weight (LWR) and length–length relationships (LLR) of G. equulus are described for the first time. A total of 1121 specimens (511 males; 620 females) were collected using gill nets in the Yatsushiro Sea, western Kyushu, Japan. The overall allometric coefficient b of LWR was close to the isometric values ( b  =   3.088). Fulton's condition factor showed high values at the beginning of the spawning season (June–September) and peaking 2 months after the spawning season.     

Length–weight relationships for 24 fish species in a coastal lagoon of the Mexican South Pacific

Length–weight relationships were estimated for 24 species belonging to 16 families of fishes, representing a total of 15 312 measured fish, from the Carretas-Pereyra lagoon, Chiapas, Mexico. Significant length–weight relationships were found for all species. For 13 species, length–weight relationships are published for the first time.     

Length–weight and length–length relationships of 10 small fish species from the Ganges, Bangladesh

This study describes the length–weight (LWR) and length–length (LLR) relationships for ten small indigenous fish species from the lower part of the Ganges, Bangladesh, namely Ailia coila , Amblypharyngodon mola , Aspidoparia morar , Clupisoma atherinoides , Eutropiichthyes vacha , Glossogobius giuris , Gudusia chapra , Lepidocephalus guntea , Mystus vittatus , and Puntius ticto . A total of 2142 specimens, representing 10 species of 5 families used for this study were caught by traditional fishing gear from March 2006 to February 2007. Standard length (SL), total length (TL) and fork length (FL) for each specimen were measured by digital slide calipers and each body weight (BW) was taken by a digital balance. The allometric coefficient b of the LWR was close to the isometric value ( b  =   3.001) in G. giuris , although it suggested negative allometric growth in A. coila, A. morar, C. atherinoides, E. vacha, and P. ticto, whilst positive allometric growth in rest of the species. The results further indicated that the LLRs were highly correlated ( r ²  >   0.890; P < 0.01). To the best our knowledge, this study presented the first reference on LWR and LLR for most of the species in Bangladesh.     

Length–weight relationships for 12 fish species caught in Seyhan Dam Lake in southern Anatolia, Adana, Turkey

Presented are the length–weight relationships of 12 fish species [ Oncorhynchus mykiss (Walbaum, 1792); Cyprinus carpio, Linnaeus, 1758; Carassius carassius Linnaeus, 1758; Alburnoides bipunctatus (Bloch, 1782); Alburnus adanensis Battalgazi, 1944; Rutilus rutilus , Linnaeus, 1758; Squalis cephalus, Linnaeus, 1758; Tinca tinca (Linnaeus, 1758); Capoeta barroisi (Valenciennes, 1842); Silurus glanis Linnaeus, 1758; Gambussia affinis (Baird and Girard, 1853); and Sander lucioperca (Linnaeus, 1758)] from Seyhan Dam Lake, Turkey. This study provides the first estimation of length–weight relationships for two of the species ( A.   adanensis and C. barroisi ).     

Population structure, growth, mortality and estimated stock size of the introduced tench, Tinca tinca (L.), population in Lake Beyşehir, Turkey

Population structure, growth, length–weight relationship, mortality and stock size of tench, Tinca tinca (L.), was studied in Lake Beyşehir, Turkey in 2005. Totals of 3360 tench (1865 males; 1795 females) were captured with gill- and trammel-nets of various mesh sizes. Male to female ratio was 1.04 : 1. The study covered length year classes. Fork lengths and total weights ranged from 9 to 37 cm and 13 to 815 g. For all individuals, the von Bertalanffy growth equation and length–weight relationship were L _t = 54.2[1−exp(−0.1350( t  + 1.0281)] and W  = 0.0151  L ^2.9993, respectively. Growth performance index and mean condition factor of the tench population were 2.598 and 1.513, respectively. Mortality rates were Z  = 1.97 year⁻¹, M  = 0.29 year⁻¹ and F  = 1.68 year⁻¹ for total, natural, and fishing mortality, respectively. The exploitation rate was E  = 0.85, and the percentage of surviving fish was 13.9%. Tench stock was assessed as about 6–7 million individuals and 1450–1500 tonnes in biomass. It was determined that maximum sustainable yield could be obtained with an 80% level of the current fishing effort.     

Age, growth and food composition of Scorpaena porcus (Linnaeus, 1758) in the southeastern Black Sea

Samples of 525 Scorpaena porcus (Linnaeus, 1758) were collected from the southeastern Black Sea between January 2002 and May 2003 for information on age, growth, length–weight relationships and stomach contents. Total length of sampled fish ranged from 4.6 to 22.9 cm and total weight from 1.3 to 220 g. The sex ratio (1 : 1.61) was biased toward females (P < 0.05). Positive allometric growth was determined in the collected samples. The length–weight relationship for all individuals was described by the parameters a  = 0.0149 and b  = 3.09, with r ² = 0.99. The sample was composed of five age-classes (0–7 years). Three growth models were used to identify the growth characteristics: von Bertalanffy,     ; logistic,     ; and Schnute and Richards,     . Among these, the Schnute and Richards model was best fitted to the data as     The diet was composed of Carcinus mediterraneus (18.2%), Crangon crangon (12.1%), unidentified crab species (10.6%), Gobius sp. (4.6%), Palaemon sp. (4.5%), Macropipus sp. (4.5%), Engraulis encrasicholus (1.5%), Gastropoda (1.5%), and unidentified remains (34.9%).     

Evaluation of Genetic Variation in the Clown Knifefish, Chitala chitala, Using Allozymes, RAPD, and Microsatellites

Twenty-seven enzyme systems, six random amplified polymorphic DNA (RAPD) primers, and two microsatellite loci were tested to determine intraspecific divergence in the natural population of the endangered Indian featherback fish, Chitala chitala, for the first time. The 262 samples of C. chitala were collected from six riverine locations in India: the Satluj, Ganga (Ghagra, Bhagirathi, and Brahmaputra), Mahanadi, and Narmada river systems. The analysis revealed population subdivisions, with an F_ST value from 0.1235 (95% confidence 0.0868–0.1621) for RAPD and a combined F_ST of 0.0344 (95% confidence 0.0340–0.0350) for microsatellite loci. An analysis of 38 allozyme loci did not reveal any polymorphism in the samples from any of the riverine localities; a possible explanation for this could be that the ancestors of Chitala could have faced a population reduction in prehistoric periods, as low allozyme variation is also reported for other species of Chitala from south Asia.     

Length–weight and length–length relationships of fish species from the Aegean Sea (Greece)

We present the relationships between total (TL), fork (FL) and standard (SL) length for 37 fish species and the relationships between TL and wet weight for 40 fish species from the Aegean Sea (Cyclades; Greece). The relationships between TL, FL and SL were all linear (for all cases: r ² > 0.928). The values of the exponent b of the length–weight relationships ranged from 2.235 to 3.704.     

Generalised regressions provide good estimates of insect and spider biomass in the monsoonal tropics of Australia

Abstract  The estimation of arthropod biomass is often important in studies of terrestrial ecosystem structure and function, including analyses of the relative importance of different arthropod taxa in the diet of insectivorous animals. In order to estimate arthropod biomass in eucalypt woodlands and rehabilitated mine-land in the monsoonal tropics of northern Australia, insect morpho-species ( n  = 693) and spider morpho-species ( n  = 100) were collected, sorted, then weighed and measured. Body length–weight regressions were determined for spiders, nine insect orders and all insects combined. There was a significant relationship between body length and weight for all taxonomic groups, with the power model being a better predictor than linear or exponential models for all groups except Diptera (which was best predicted by the linear model). Whilst Schoener (1980) found that the length–weight regression slopes of neotropical insects (all orders combined, as well as several individual orders) differed from those of their temperate North American counterparts, our comparisons between monsoon-tropical and temperate Australian arthropods suggested differences among Dipterans and spiders only. We conclude that generalised regressions provide adequate estimates of arthropod biomass across Australia, providing that the body proportions of the dominant taxa do not vary substantively.     

Length–weight and length–length relationships of three endemic butterflyfish species (Chaetodontidae) from coral reefs of the Northwestern Hawaiian Islands, USA

Length–weight and length–length relationships are presented for three species of butterflyfish endemic to the Hawaiian Islands and Johnston Atoll. From specimens collected within the Papahānaumokuākea Marine National Monument (PMNM), the weight–length relationships were determined for Chaetodon fremblii as W  = 0.029SL^3.17, Chaetodon miliaris as W  = 0.042 SL^3.00, and Chaetodon multicinctus as W  = 0.029SL^3.19 where weight, W , is reported in grams and standard length, SL, in centimeters. Length-frequency data and equations to calculate total length from standard length are also presented.     

Photoperiod as Cues for Determining Optimal Foraging in Developmental Stages in Chitala chitala Hamilton, 1822

Photoperiod plays an important role in controlling the feeding rhythmicity of juvenile fishes. Studies on feeding and spatial distribution pattern were made on wild populations of different juvenile stages of Chitala chitala, a threatened species in India. Results indicated that the prey preference of the fish increased with advancement of developmental stages. Moreover, nocturnal feeding was found to be more significant in the juveniles. Thus, feeding pattern of the different juvenile stages of Chitala is characterized by voracious predatory activity at dark condition. The vector controlling potential of the juvenile stages of Chitala specifically on mosquito and chironomid larvae was also significant. Studies on the distribution pattern of juvenile fishes were made with various combinations, viz. with or without food, in open surface and structured environments and observed during day as well as in dark regime. The juvenile distribution was clumped in open and closed environment during day time to minimize the chances of predation and juvenile mortality irrespective of food availability. A random distribution of juvenile fishes seemed to be advantageous for increasing feeding activity as observed in the experiment. This study is a pointer to the survival strategy of the larvae of C. chitala in their natural habitat which may be important from the perspective of conservation.     

Length–weight relationships of Wallago attu and Sperata sarwari from the Indus River, southern Punjab, Pakistan

The present study describes the length–weight parameters of Wallago attu and Sperata sarwari from the Indus River, southern Punjab, Pakistan with W  = 0.001698  L ^3.27 for W. attu and W  = 0.001698  L ^3.28 for S. sarwari . The values of the slope b are significantly higher than b  = 3.0, which shows that the weight grows more rapidly as compared to the cube of the length. Thus it was concluded that body proportions changed as fish grew in size.     

Age, growth and reproduction of the black scorpionfish, Scorpaena porcus (Pisces, Scorpaenidae), on the Black Sea coast of Turkey

Age, growth and reproduction of the black scorpionfish, Scorpaena porcus were studied in specimens from the coast of the Sinop Peninsula (Black Sea) between March 2002 and April 2003 in order to characterize these population parameters in comparison to specimens from populations of nearby regions. A total of 1086 specimens was captured by beam trawl at the depths between 0 and 30 m. The total number of females (510) was significantly higher than that of males (373). Total length of males and females ranged between 5.7 and 23.6 cm, and 4.9 and 31.7 cm, respectively. The length–weight relationship showed a positive allometric growth. Females grew faster and reached a larger size at age than males ( L _∞ = 111.9 cm, K  = 0.035 year⁻¹, φ' = 2.64 for females, and L _∞ = 74.6 cm, K  = 0.054 year⁻¹, φ' = 2.49 for males). The age range estimated was up to 8 years for females and 5 years for males. Reproduction likely occurs between June and September. Sex ratio varied greatly with season, perhaps indicating different seasonal migratory patterns in adults of different sex. An inverse correlation between gonadosomatic index (GSI) and hepatosomatic index (HSI) was evident during the reproduction seasons. The mean size at first sexual maturity was 17.5 cm TL for females, and 16.7 cm TL for males.     

Mitochondrial sequence-based evolutionary analysis of riverine–swamp hybrid buffaloes of India indicates novel maternal differentiation and domestication patterns

In this study, mitochondrial D-loop sequence data on riverine, swamp and hybrid buffaloes from India have been generated and compared with other reported Indian riverine, Chinese and Bangladeshi swamp buffalo populations. Sequence analysis revealed the presence of 132 haplotypes, with a haplotype diversity of 0.9611 ± 0.0045 and a nucleotide diversity of 0.04801 ± 0.00126. For the first time, the existence of riverine–swamp hybrids among the Indian Chilika buffalo population has been recorded, having 49 chromosomes, which was also confirmed by mitochondrial haplotype sharing between Chilika and Indian swamp as well as Chinese swamp buffalo populations in the network analysis. Phylogenetic analysis documents the sharing of reported pre-domestication haplogroups ‘SA1’, ‘SA2’, ‘SA3’ and ‘SB1’ between the Chilika and swamp buffalo populations of India, China and Bangladesh, an indication of the migration of swamp buffaloes towards Bangladesh and adjoining lower parts of India and north towards Chinese domestication sites. The results have also been supplemented by multidimension scaling, grouping Indian and Chinese swamp buffaloes more closely together with Bangladeshi buffaloes, but into a separate quadrant, whereas Chilika grouped away from other riverine as well as swamp buffaloes. These findings thus confirm the previous reports that the northeast region of India, close to the Indo-China border, is the point of evolution of swamp buffaloes with multiple sites of domestication.     

Age, growth and mortality of the Mediterranean amberjack Seriola dumerili (Risso 1810) from the south-eastern Adriatic Sea

The age, growth and mortality of the Mediterranean amberjack Seriola dumerili (Risso 1810) were determined in 298 specimens collected in the south-eastern Adriatic Sea (Donji Molunat Bay) from 17 May to 26 June 1997. The total length ranged from 32.0 to 160.0 cm and weight from 0.5 to 46.5 kg. Ten age classes, ranging from 1° to 10° years were defined by scale readings. Mean total length and weight-at-age data were used to estimate the growth parameters of the von Bertalanffy equation: L _∞=174.6 cm, K =0.190, t ₀=–0.314; W _∞=79.01 kg, K =0.139 and t ₀=–0.746. The length–weight relationship was estimated at: W =0.000123 ×  L ^2.847. The overall sex ratio was 1 : 1.06 in favour of males. Total ( Z ) and natural ( M ) mortality were found to be 0.41 years⁻¹ and 0.30 years^–1, respectively. The exploitation ratio ( E =0.27) indicates that the fishing pressure on the Mediterranean amberjack was low in the investigated region.     

Age, growth and mortality of picarel, Spicara smaris L. (Pisces: Centracanthidae), from the eastern Adriatic (Croatian coast)

Age, growth and mortality of picarel Spicara smaris L. collected in the eastern middle Adriatic during April and May in 1999 were studied. The total lengths of individuals ranged from 6.3 to 19.8 cm, and the weight from 2.2 to 78.3 g. The slopes ( b values) of the total length–weight regressions indicated negative allometric growth for females ( b =2.8± 0.03) and isometric growth for males ( b =3.08±0.04). The oldest female and male were 4 and 6 years, respectively. The von Bertalanffy growth parameters for the sexes combined were ( L _∞=22.76 cm, K =0.277, t ₀=−0.793). The overall sex ratio was 1 : 4.1 in favour of females. Individuals larger than 17.9 cm were all males.     

Length–weight relationships and seasonality in reproduction of six commercially utilized fish species in the coastal lagoon of Tres Palos (Mexico)

The length–weight relationship parameters and seasonal reproductive cycle are recorded for six commercially important fish species caught in the coastal lagoon of Tres Palos. The length–weight information is new to the literature for three of these species (spot cichlid, spotted sleeper, Pacific fat sleeper) and is within the expected range for the other three (widehead sea catfish, three spot cichlid, white mullet). Differences between sexes are statistically significant for four species and deviations from isometric growth are indicated in three species. The reproductive period for the Pacific fat sleeper differed substantially from the period reported for this species in Ecuadorian waters.     

Length–weight relationships of deep-sea fishes from the western Bering Sea

Length–weight relationships are lacking for most deep-sea fishes. This study presents length–weight relationships for 42 species from the western Bering Sea. Results show significantly different relationships between females and males for 11 species and between juveniles and adults of four species. A plot of length–weight estimates, log a over b , showed the deep-sea fishes in this study to be more of the elongated shape compared with other marine fishes.