Diet and feeding ecology of black-barred halfbeak Hemiramphus far(Forsskal, 1775) (Hemiramphidae) from Karachi coast of Pakistan

Objective:To describe the diet and feeding ecology ofHemiramphus far (H. far) through investigating the stomach contents. <br> Methods: Sampling of total 430 individuals ofH. far was carried out from commercial catches landed at West Wharf fish harbor of Karachi coast, Pakistan during January–December 2010. The total length and weight of each individual were recorded. Samples were parted into Group 1 (15–20 cm,n = 240) and Group 2 (21–26 cm,n = 190), to estimate changes in diet with fish size. To remove alimentary canal, fishes were dissected and kept into 10% formalin. Then gut contents were examined under a light microscope for each intestine. Stomach fullness as well as dietary composition was ascertained from gut contents. Examination and analyses were conducted using frequency of occurrence and numerical method. <br> Results:The examination confirmed 47.67% stomach as empty. Furthermore, our study revealed that the diet ofH. far consists of fishes, isopods, ostracods,Daphnia, shells, algae, unidentified plants and animal materials. This study proved thatH. far is an omnivorous fish feeding on fishes, isopods, shells, algae and plant and animal originated different food items. According to the Schoener overlap index, there was no significant difference in feeding of the two length groups ofH. far (C = 0.833). In addition, the Shannon-Wiener index presented that in Group 1, the prey diversity of the halfbeak was lower (H = 0.90) than that of Group 2 (H = 1.02). <br> Conclusions: The findings of the present study would be very effective for sustainable management of black-barred halfbeak fishery in the Karachi coast of Pakistan and the surrounding ecosystems.

Seasonal variations of heavy metal concentration in Sardinella sindensis(Day,1878)from Balochistan coast

Objective:To determine Fe,Cu,Zn,Pb and Cd concentrations in muscle of sind sardinella[Sardinella sindensis(S.sindensis)]from Balochistan coast,Pakistan.Methods:S.sindensis were collected from Balochistan coast,Pakistan,at autumn inter monsoon,north east monsoon,spring inter monsoon and south west monsoon during October 2005-September 2006.All samples were analyzed for Fe,Cu,Zn,Pb and Cd by AAnalyst 700 flame atomic absorption spectrophotometer.Results:Generally,S.sindensis caught from Balochistan coast showed the accumulation level of Fe[(16.88±5.60)μg/g],Cu[(2.74±1.89)μg/g],Cd[(0.29±0.25)μg/g],Zn[(4.29±2.31)μg/g]and Pb[(0.24±0.24)μg/g]in the muscle tissues.Conclusions:The metal concentrations in fish from Balochistan coast observed in this study were lower than the limit values.Therefore,all metal accumulations in S.sindensis have to be monitored continuously,especially in this region.

Diets of Halfbeak Hemiramphus lutkei(Valenciennes,1847)from Karachi Coast,Pakistan

Objective: To investigate the diets of the Lutke’s halfbeak, Hemiramphus lutkei (H. lutkei) to determine the food and feeding habits. Methods:Samples of H. lutkei were collected from the landing sites of Karachi Coast, Pakistan. Total length was measured to the nearest 0.01 cm using digital slide calipers, and total body weight was measured using an electronic balance with 0.01 g accuracy. The dietary composition was determined from gut content examination and analysis was done using frequency of occurrence and numerical methods. To assess the changes in diet with size, H. lutkei were divided into two size groups, Group 1:14-20 cm (n=250) and Group 2:21-25 cm (n=160). Results:The total length and body weight of the sampled specimens ranged from 14 to 25 cm and 10 to 23.5 g, respectively. Out of the studied specimens, 45.12%fish stomachs were found to be empty. Dietary composition revealed daphnia, small fish, isopods, unidentified animal materials, ostracods and unidentified plant materials in the gut contents of Lutke’s halfbeak. Therefore, H. lutkei is omnivore fish feeding on algae, zooplankton, small fishes and different food items of both plant and animal origin. According to the Schoener overlap index (C), there was no significant difference in feeding of the two length groups of H. lutkei (C=0.833). On the other hand, the Shannon-Wiener index showed that the prey diversity of the Lutke's halfbeak in Group 1 was lower (H'=1.545) than that of Group 2 (H'=1.653). Conclusions:This study reports the first description of diets for H. lutkei, which would be useful for the sustainable management of this fishery in the coast of Pakistan and also neighboring countries.

Physicochemical parameters and seasonal variation of coastal water from Balochistan coast,Pakistan

Objective:To determine common physico-chemical parameters of coastal water.Methods:Physicochemical properties of water were determined according to the standards of the American Public Health Association.Generally,all those parameters were recorded a small variation between stations.The variation in physico-chemical parameters like salinity,temperature,dissolved oxygen and pH at Gwadar(Coastal water of Balochistan)were recorded.Results:The range of air temperature of coastal water of Balochistan during 2004 and 2006 varies from 25℃to 37℃,water temperature ranged from 15.00℃to 33.00℃,pH ranged from 7.08 to 8.95,salinity ranged from 37.4‰to 41.3‰and dissolved oxygen ranged from 5.32 to 8.67 mg/L.Conclusions:Results showed that these parameters of Balochistan coast of Pakistan is not dangerous for marine habitat and the use of these parameters in monitoring programs to assess ecosystem health has the potential to inform the general public and decision-makers about the state of the coastal ecosystems.To save this vital important habitat,the government agencies and scientists should work with proper attention.