UGROŽENE VRSTE RIBA U SVIJETU: Plotosus canius Hamilton, 1822 (Siluriformes: Plotosidae)

Gray eel catfish Plotosus canius is a vulnerable species in Bangladesh. The wild populations are declining as a result of over-exploitation, destruction of spawning grounds, various ecological changes in their natural habitats and lack of appropriate management. Establishment of suitable sanctuaries in selected areas of estuaries, streams, canals and lakes is suggested for the conservation of the populations.Sivi jeguljoliki som, Plotosus canius, je osjetljiva vrsta u Bangladešu. Divlje populacije opadaju kao rezultat pretjeranog iskorištavanja, uništavanja staništa za mrijest kao i raznih ekoloških promjena u njihovom prirodnom staništu te zbog nedostatka odgovarajućeg gospodarenja. Za očuvanje populacije predlaže se uspostava rezervata u odabranim područjima estuarija, potoka, kanala i jezera

Estimation of population structure, growth and condition of Parastromateus niger in the Bay of Bengal : suggestions for catchable sizes

Black pomfret (Parastromateus niger) is one of the major commercial species of pomfret fishery in Bangladesh. This study illustrates the population structure (Length Frequency Distribution, LFD), relationship between length and weight (LWR), relationships between length and length (LLRs), Fulton’s condition factor (KF) and relative weight (WR) of P. niger in the Bay of Bengal (BoB). A total of 225 P. niger were collected from the four locations during January to December 2020. LFD analysis indicates three length classes 21-27 cm, 30-32 cm and 35-37 cm, respectively. This species showed isometric growth pattern (b = 2.981) that indicates that the size and weight increases proportionally and the surrounding habitat provides favourable environment for the growth. LWR between TL and BW were highly correlated (r² = 0.951). LLRs also showed significant correlation between TL and SL (r² = 0.845) and TL and FL (r² = 0.861). The mean value of KF was found as 1.60 which indicates that the BoB provides healthy environment for this species. The mean value of WR (101.09) indicates that the relationship between prey and predator was in balanced condition. This study suggests optimum catchable length for P. niger at 27 cm. Therefore, these findings could provide important information to design effective conservation and management planning for this species

UGROŽENE VRSTE RIBA U SVIJETU: Labeo bata (Hamilton, 1822) (Cypriniformes: Cyprinidae)

Minor carp Labeo bata is an endangered fish species in Bangladesh. This fish is one of the commercially and nutritionally valuable food fish in Asian countries including Bangladesh, India and Pakistan. L. bata is an important target species for small scale fishermen in Bangladesh who use a variety of traditional fishing gears. However, natural populations are seriously declining due to loss of habitat, siltation in the river basin, indiscriminate killing of fry and fingerlings, water pollution by industrial and domestic waste, agrochemicals and overexploitation. This paper recommends the sustainable conservation measures of this endangered fish species in Bangladesh and neighboring countries.Bata, Labeo bata, je ugrožena vrsta ribe u Bangladešu. Ova vrsta je od komercijalne važnosti te nutritivno vrijedna hrana u azijskim zemljama, uključujući Bangladeš, Indiju i Pakistan. L. bata je važna lovna vrsta za male ribare u Bangladešu koji pritom koriste razne tradicionalne ribolovne alate. Međutim, prirodne populacije ozbiljno opadaju zbog gubitka staništa, zamuljenja riječnih korita, neselektivnog ubijanja mlađi i mladunaca, onečišćenja voda industrijskim i kućnim otpadom, agrokemikalijama i prekomjernim iskorištavanjem. U radu se preporučuju održive mjere očuvanja ove ugrožene vrste riba u Bangladešu i susjednim zemljama

UGROŽENE VRSTE RIBA U SVIJETU: Eutropiichthys vacha (Hamilton, 1822) (Siluriformes: Schilbeidae)

River catfish Eutropiichthys vacha is one of the foods high in nutritional value in Asian countries. However, natural populations have seriously declined or are on the verge of extinction due to over-exploitation and various ecological changes in its natural habitats, leading to an alarming situation which deserves high conservation attention. This paper suggests conservation measures that should be taken into account towards the preservation of the remnant isolated population of E. vacha in Asian countries.Riječni som, Eutropiichthys vacha, služi kao komercijalno visoka, nutritivno vrijedna hrana u azijskim zemljama. Međutim, prirodne populacije ozbiljno su opale ili su na rubu izumiranja zbog prekomjernog iskorištavanja i raznih ekoloških promjena u svojim prirodnim staništima, što dovodi do alarmantne situacije te je potreban visok stupanj zaštite. U radu se predlažu mjere zaštite koje treba uzeti u obzir kako bi se očuvao ostatak izolirane populacije E. vacha u azijskim zemljama

Temporal variations of sex ratio and growth pattern of critically endangered catfish Clupisoma garua from the Ganges river of north-western Bangladesh

647-653This research work states the temporal variations of sex ratio (SR), length-frequency distributions (LFDs), growth type based on length-weight relations (LWRs) and length-length relations (LLRs) of Clupisoma garua from the Ganges river of north-western Bangladesh. A total of 1200 specimens (male=630, female=570) were sampled using traditional fishing gears during May 2014 to April 2015. Then, total length (TL), standard length (SL) and fork length (FL) were taken to about 0.1 cm, and body weight (W) was taken to 0.1 g accuracy. The overall SR (male: female=1.0:0.90) did not vary statistically from the expected ratio of 1:1 (df =1, χ2 = 3.00, p>0.05). However, monthly variations of SR indicate males were higher in each month except June-August when females were greater in percentage. The LFDs showed that in males C. garua, ranged from 3.8-25.9 cm TL and females 3.9-26.3 cm TL. The LFDs for both sexes did not pass the normality; and Mann-Whitney U-test showed significant differences between sexes (pbvs. FL and TL vs. SL) of C. garua were highly significant (pr2 values >0.975. Finally, the findings of this study will be helpful for fishery biologists and conservationists to recommend adequate policy for the sustainable fishery of C. garua in the Ganges river and surrounding ecosystem

Population Biology of the Indian River Shad, Gudusia chapra (Clupeidae) in the Old Brahmaputra River, North-Eastern Bangladesh

Population biology including population structure, reproduction, length-weight relationship and condition factor of a commercially important clupeid freshwater fish, Gudusia chapra was studied in the Old Brahmaputra River, Bangladesh during January-December 2009. In the present study, a total of 2032 specimens (1091 male; 941 female) were collected. The overall sex ratio showed significant difference from the expected value 1:1 (male: female = 1:0.86, χ2 = 11.07, p<0.001). Length-frequency distribution showed a size predominance of females over males, where mean female size consistently exceeded that of males throughout the year. Female size at first sexual maturity was estimated as 8.3 cm in standard length (SL). Monthly gonadosomatic index (GSI) was higher during March-September with a peak in April, indicating this was the main spawning season. The allometric coefficient b of the length-weight relationship (LWR) indicated negative allometric growth in males and females, but the analysis of covariance (ANCOVA) showed significant differences in slope and intercept between the sexes (p<0.001). Fulton’s condition factor by months and SLs varied in both sexes and was attributed to variations in GSI with maturity

Biometry, sexual maturity, natural mortality and fecundity of endangered halfbeak Dermogenys pusilla (Zenarchopteridae) from the Ganges River in northwestern Bangladesh

1548-1555The present study express the biometry, including length-weight relationships (LWRs) using 12 equations, length-length relationships (LLRs) using 15 equations, condition factors (allometric, KA; Fultonʹs, KF; relative, KR; and relative weight, WR), form factor (a3.0), first sexual maturity (Lm), natural mortality (MW) and fecundity (FT) of Dermogenys pusilla from the Ganges River, northwestern Bangladesh. A sum of 75 individuals was hardly collected using cast net and gill net during July 2013 to June 2014. In our study total length ranged from 6.6–16.1 cm for male and 7.5-15.6 cm for female and fin formula was- dorsal, D. 12 (4/8); pectoral, P1. 11 (2/9); pelvic, P2. 6 (1/5); anal, A. 13-14 (2-3/11-12) and caudal C. 18-20 (4/14-16). All LWRs were highly significant (P r2, BW vs. FL was the best fitted model among 12 equations for both sexes. The analysis of covariance (ANCOVA) revealed significant differences between males and females for LWRs (P P r2 values ≥ 0.940. According to highest value of r2, LLR by TL vs. FL was the best suited model among 15 equations for both genders. Based on Pearson correlation values, KF was highly correlated with BW and TL; thus KF can be used for the wellbeing of this species in the Ganges River. The a3.0 was 0.0025 for male and 0.0024 for female. The Lm was 9.70 cm TL for male and 9.40 cm TL for female. Also, the MW was 1.13, 1.41 year-1 for males and females respectively, and the fecundity was ranged from 620-1544 (mean ± SD = 1125 ± 248). Therefore, the findings of this study would be very effective for sustainable conservation of this endangered species in the Ganges River and surrounding ecosystem

UGROŽENE VRSTE RIBA U SVIJETU: Pethia ticto (Hamilton, 1822) (Cypriniformes: Cyprinidae)

The threatened Ticto barb Pethia ticto is a small indigenous fish species widely distributed in the natural waters of Asian countries. Previously it was known as Puntius ticto. Natural populations have been reduced seriously to the verge of extinction due to excess exploitation and ecological changes in their natural habitats. This paper suggests the actions for the conservation of the remaining isolated population of P. ticto in Asian countries.Ugrožena indijska autohtona vrsta, Pethia ticto, široko je rasprostranjena u prirodnim vodama azijskih zemalja. Ranije je bila poznata kao Puntius ticto. Prirodne su populacije ozbiljno smanjene te na rubu izumiranja zbog viška eksploatacije i ekoloških promjena u njihovim prirodnim staništima. U radu se predlažu mjere za očuvanje preostalih izoliranih populacija P. ticto u azijskim zemljama

UGROŽENE VRSTE RIBA U SVIJETU: Botia dario (Hamilton, 1822) (Cypriniformes: Cobitidae)

Bengal loach Botia dario is a valuable food fish in South Asian countries including Bangladesh, Bhutan, India and Nepal. However, the wild population is declining due to heavy harvest, habitat loss and its ecological changes. This paper suggests actions for the conservation of the lasting isolated populations of B. dario in Asian countries.Benegalski vijun, Botia dario, u južnim azijskim zemljama, uključujući Bangladeš, Butan, Indiju i Nepal, ima visoku važnost u prehrani. Međutim, divlje populacije su u opadanju zbog teškog iskorištavanja, gubitka staništa i ekoloških promjena. U ovom članku se predlažu akcije za očuvanje posljednjih izoliranih populacija B. dario u azijskim zemljama

UGROŽENE VRSTE RIBA U SVIJETU: Mystus gulio (Hamilton, 1822) (Siluriformes: Bagridae)

Long whiskers catfish Mystus gulio is a commercially important food fish in Asian countries. But natural population is decreasing due to over-exploitation and various ecological changes in its natural habitats. This paper suggests the steps for the conservation of the remnant isolated population of M. gulio in Asian countries.Som dugih brkova, Mystus gulio, je komercijalno važna riba u azijskim zemljama. Ipak, opadaju prirodne populacije zbog pretjeranog iskorištavanja i raznih ekoloških promjena u njihovim prirodnim staništima. U radu se predlažu koraci za očuvanje ostatka izolirane populacije M. gulio u azijskim zemljama