8,319 research outputs found

    On the breeding habits of the ribbon fish Trichiurus haumela (Forsk.)

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    Although ribbon fishes provide an important fishery along the east a nd west coast; of India, their shoaling, breeding and spawning habits have not been investigated in detail. VenkatramanG gave a short account of the feeding habits of ribbon fishes of the Malabar coast, and Chidambaram and Venkatraman1 dealt with the natural history of ribbon fishes

    The Ribbon Fishes

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    The ribbon-fishes, also called the hair tails or cutlass fishes elsewhere, occupy an important place among the food fishes of India. They are abundant and cheap and as such are also preferred by poor people. Large fishes are consumed fresh and transported to the interior markets but the smaller ones in excess of the local requirements are usually sun dried on the beach. Their non-fatty nature and ribbon-like bodies make them suitable for rapid preservation by sun drying. Thus, during times of glut, large quantities of the cured fish become available which ultimately find their way to interior markets at reasonably low price

    The contribution of the pectoral fins, body, and the ribbon fin to turning maneuvers of a gymnotiform swimmer

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    Turning is an ecologically important maneuver in fishes as it is used in prey detection, predator avoidance, and to navigate complex environments. Fishes with traditional control surfaces primarily use body bending and pectoral fins to turn. However, little is known about how fishes with atypical control surfaces facilitate turning. This study investigated the weakly electric Black ghost knifefish (Apteronotus albifrons: Apteronotidae) with an atypical control surface, namely a ribbon fin. To investigate how a fish with an atypical control surface performs turning maneuvers, A. albifrons was filmed performing small and large turns and during steady swimming using high speed videography. 3D kinematic analysis of the body, pectoral fins, and ribbon fin revealed that pitch angle, ribbon fin amplitude, and asynchronous movements of the pectoral fins dominated steady swimming while ribbon fin wavelength, frequency, wave speed, and pectoral fin flapping frequency contributed to both small and large turns. Digital particle image velocimetry (DPIV) showed that the ribbon fin generates larger counter rotating vortices during turning than is produced during steady swimming. All three control surfaces contributed to steady swimming and large turns while small turns relied mostly on movements of the pectoral and ribbon fins. Given the contribution of the ribbon fin during small and large turns in A. albifrons, the role of atypical control surfaces is likely more important than previously assumed

    Heavy landings of ribbon fishes

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    Heavy landings of ribbon fishes where observed at Rameswaram in March. Pair trawlers operating about 15 km North-eastoff Rameswaram (9 10'- 9°20'N latitude and 79° 20'- 79° 35' E longitude) at about 12m depth, had landed an estimated 45.18 tonnes of ribbon fish at a cpeu of 21.8 kg

    Hydromechanics of swimming propulsion. Part 3. Swimming and optimum movements of slender fish with side fins

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    This paper seeks to evaluate the swimming flow around a typical slender fish whose transverse cross-section to the rear of its maximum span section is of a lenticular shape with pointed edges, such as those of spiny fins, so that these side edges are sharp trailing edges, from which an oscillating vortex sheet is shed to trail the body in swimming. The additional feature of shedding of vortex sheet makes this problem a moderate generalization of the paper on the swimming of slender fish treated by Lighthill (1960a). It is found here that the thrust depends not only on the virtual mass of the tail-end section, but also on an integral effect of variations of the virtual mass along the entire body segment containing the trailing side edges, and that this latter effect can greatly enhance the thrust-making. The optimum shape problem considered here is to determine the transverse oscillatory movements a slender fish can make which will produce a prescribed thrust, so as to overcome the frictional drag, at the expense of the minimum work done in maintaining the motion. The solution is for the fish to send a wave down its body at a phase velocity c somewhat greater than the desired swimming speed U, with an amplitude nearly uniform from the maximum span section to the tail. Both the ratio U/c and the optimum efficiency are found to depend upon two parameters: the reduced wave frequency and a 'proportional-loading parameter', the latter being proportional to the thrust coefficient and to the inverse square of the wave amplitude. The basic mechanism of swimming is examined in the light of the principle of action and reaction by studying the vortex wake generated by the optimum movement

    Estimation of production trend of the depik, Rasbora tawarensis (Teleostei, Cyprinidae), in Lake Laut Tawar, Indonesia

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    The objective of the present study was to evaluate the production trend of the depik (Rasbora tawarensis) during the last two decades in Lake Laut Tawar. The production trend was examined based on the catch per unit efforts. The direct sampling, fishermen catches collection and fishermen interview were conducted to collect actual fish catches. The results showed that the depik, R. tawarensis production (indicated by the catch-per-unit effort (CPUE)) was seasonally dependent where the CPUE was higher in the rainy season compared to dry season. In addition, the CPUE was higher in the new moon according to lunar cycle. The production of depik in particular and fishes of Lake Laut Tawar in general are declining dramatically during the last two decades. The decrease in the water levels, destructive fishing gears, the presence of introduced species and pollution are the main reasons suggested for this phenomenon.</p

    Fishes of the Antoine River, Little Missouri River System, Southwestern Arkansas

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    The fishes of the Antoine River (Little Missouri River system) in southwestern Arkansas were surveyed from September, 1980 - June, 1982. Thirty-four field collections plus literature and museum records, revealed a total of 60 species in 29 genera representing 16 families to presently inhabit the river system. Comments are presented on life history aspects, systematics and occurrence of fishes in the study area

    Fishes of the Antoine River, Little Missouri River System, Southwestern Arkansas

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    The fishes of the Antoine River (Little Missouri River system) in southwestern Arkansas were surveyed from September, 1980 - June, 1982. Thirty-four field collections plus literature and museum records, revealed a total of 60 species in 29 genera representing 16 families to presently inhabit the river system. Comments are presented on life history aspects, systematics and occurrence of fishes in the study area

    Ecology of Juvenile Walleye Pollock, Theragra chalcogramma: Papers from the workshop "The Importance of Prerecruit Walleye Pollock to the Bering Sea and North Pacific Ecosystems" Seattle, Washington, 28-30 October 1993

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    The Alaska Fisheries Science Center (AFSC), National Marine Fisheries Service (NMFS), hosted an international workshop, 'The Importance of Prerecruit Walleye Pollock to the Bering Sea and North Pacific Ecosystems," from 28 to 30 October 1993. This workshop was held in conjunction with the annual International North Pacific Marine Science Organization (PICES) meeting held in Seattle. Nearly 100 representatives from government agencies, universities, and the fishing industry in Canada, Japan, the People's Republic of China, Russia, and the United States took part in the workshop to review and discuss current knowledge on juvenile pollock from the postlarval period to the time they recruit to the fisheries. In addition to its importance to humans as a major commercial species, pollock also serves as a major forage species for many marine fishes, birds, and mammals in the North Pacific region. (PDF file contains 236 pages.
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