Showing papers on "Fishing published in 1971"

Ecological Aspects of Fishery Research

Abstract: Publisher Summary This chapter discusses the ecological aspects of fishery research. It is noted that most fishery research is carried out in government laboratories, so that the research is expected to produce results of clear practical value. It is important for a fishery research worker to be able to visualize the results of work that can be applied in the interests of the fishing industry. In context to the applications of fishery research, the immediate effects are concerned mainly with direct improvement of catches. Fishing is still in the hunting or primitive pre-agricultural phase, however hunting is done with very advanced weapons. The modern fishing vessel has a wealth of modern equipment for detecting, catching, or processing the fish. Ecologists can give guidance on the most promising areas for fishing. The biggest impact on the ecological sciences on the fishing industry is produced by conservation and management of fishery resources. Essentially, the impact of conservation and management on the fishing industry, the scientific conclusions, or the most important aspects, can be summarized by using a single curve relating the amount of fishing to the average catch.

The Economic Life

Abstract: This part of the world was brought under cultivation by the peoples of Timor. In Miomafo, Insana and Beboki these were the Atoni, or, as they call themselves, the Atoni Pah Meto (= people of the dry land). This name implicitly indicates the type of cultural choice made by them, as they avoid the sea and the coast. They do not know any names of fish, and do not go fishing or sailing — contacts with peoples from other islands were not established or maintained by them.

Recent advances in the fish by‐products industry

Abstract: In recent years the fish by‐products industry has grown more rapidly than any other segment of the world's fisheries. Production of fish meal, the primary product of the industry and an important feed ingredient, rose from 1,525,000 metric tons in 1958 to 5,080,000 metric tons in 1968. This tremendous increase in production was the result of improved fishing methods, expansion of established fisheries, and the development of new fisheries, particularly the anchoveta fishery of Chile and Peru. Although markets for fish meal were severely disrupted during the early part of the expansion, they subsequently exhibited a high order inelasticity and provide the basis for profitable operations.

A description of certain indigenous fishing methods from Southern Dahomey

Abstract: A survey of certain Dahomean fishing methods showed them to be specifically adapted to the exploitation of floodplains and shallow water lagoons. Several types of fish-parks are described, ranging from small installations thaI funclion as refuge traps, to larger constructions that act as a form of fish culture. Ponds are also dug in the floodplains in order to conserve fish isolated during the dry season. These methods all give high yields and are worthy of consideration for use elsewhere on the African continent.

Relative Rates of Utilization by Commercial and Sport Fisheries of Atlantic Salmon (Salmo salar) from the Miramichi River, New Brunswick

Abstract: Studies of naturally produced Atlantic salmon (Salmo salar) smolts, marked from 1950 to 1961 on tributaries of the Miramichi River by differential finclipping, indicated that commercial fisheries accounted for over 60% of their total utilization as adults. The bulk of commercial recoveries was about equally divided among Newfoundland traps, Miramichi drift nets, and Miramichi trapnets; the remainder came from various commercial catches in the Maritime Provinces and Quebec. The percentages of grilse (1 sea-year fish) in commercial catches were low, 20% for Northwest Miramichi and 17% for Southwest Miramichi fish.Anglers reported 10 and 7%, respectively, of all the recaptures of Northwest and Southwest fish. All these angling recoveries were made in freshwater sections of the Miramichi River. Grilse comprised over 70% of angling recaptures.Spawning escapement accounted for 25% of the Northwest returns, of which 60% were grilse; and 19% of the Southwest returns, of which 85% were grilse.For the total of 174,...

Plastic fishing worm

Abstract: A plastic fishing lure in the general shape of a worm having head and tail portions The head portion of the lure contains a metallic hollow chamber about a freely movable ball which produces a fish-attracting noise when the lure is pulled through the water

Automatic fishing machine

Abstract: Installed alongside the gunwale of a fishing boat, this machine automatically repeats a fixed cycle of fishing operation which comprises the steps of keeping the fishing pole tip at a fixed height from the surface of the water while waiting for a fish to bite and, upon sensing the bit of a fish at the hook, swinging up the fishing pole to hoist the fish from the sea into the air, subsequently causing the fish to come free of the hook in mid-air above the boat''s deck and fall on the deck and, with the release of tension in the line, causing the fishing pole to be immediately lowered to the original position for the next bite.

An investigation of the advantages of autumn and spring stocking with brown trout Salmo trutta L. in a Yorkshire reservoir

Abstract: Batches of trout have been introduced into Chelker Reservoir in Yorkshire in the autumn and spring since the 1870's for angling purposes. Six batches of tagged, hatchery-reared brown trout Salmo trutta L. were introduced from autumn 1966 to spring 1969. During the angling season fish introduced in the spring give better catches than those stocked in the autumn. At the beginning of the season the larger fish in the spring batch are caught more often than the smaller fish from the same batch. The larger fish in the autumn batch are caught more often than the smaller fish from that batch throughout the season. The population, available to the angler from the shore was estimated to be 1491 in 1968, with 722 fish/km of shoreline. More fish survive to a second year in the reservoir than is apparent from the number of tags returned. Fish introduced in the spring usually begin growing before those introduced in the autumn, thereafter growth rates varied. The growth rate was independent of the number offish stocked up to the numbers put in. Batches of tagged trout were retained at the hatchery up to nine months to gain relevant experience of post-tagging mortalities, tag loss rate and effect of tags on growth.

Ice fishing apparatus for signalling the biting of a fish

Abstract: An ice fishing apparatus for signaling the biting of a fish, including an upright post with a pole pivotally mounted thereto and extending therefrom, the pole retained in an equilibrium position by a spring extending between post and pole. A fishing reel is mounted on the apparatus, and fishing line stored thereon passes along the pole and downward into an ice hole. The tugging of a biting fish causes the spring supported pole to oscillate about the equilibrium position along a path thereby visually signalling the biting of the fish. The reel may be positioned on the post in the path of the pivotally mounted pole so that a strong tug on the line causes the pole to swing toward and bear against the reel thereby retarding the playing out of fishing line by in creasing the drag on the line. When the equilibrium position of the pole is horizontal, the pole is substantially unaffected by wind forces acting thereon, assuring that the fisherman is not falsely signalled by pole oscillation generated by the wind.

Escapement levels and productivity of the nushagak sockeye salmon run from 1908 to 1966

Abstract: Since the inception of a commercial fishery for sockeye salmon in the Nushagak District, Bristol Bay, Alaska, the annual yields have followed a definite pattern. Catches increased during a relatively short development phase of the fishery, then stahilized for some years and then declined in two steps separated hy periods of relative stability. For years the cause of the decline had been thought to be overfishing, and various measures of cur­ tailment had been placed upon the fishing industry. Evidence is presented in this paper that the average escapement or the potential egg deposition re­ mained about the same during each of three periods (1908-1919, 1!)25-1945, and 1946-1966); hence the diminution in the runs was due not to lack of spawners but to a decline in the rate of return per spawner. So that the cause or causes of the present low reproductive potential can he ascertained, the effects of fishing on the stocks of salmon must be examined. Besides removing part of the run, the yearly commercial fishing operation may have altered either the age composition or the distribution of the escapement. Available historical records were examined for evidence of these types of changes hut largely with a negative result; therefore, the hypothesis was advanced that the observed declining rate of return per spawner is caused by a declining basic productivity of the nursery areas. The latter is then ascrib­ able to the cumulative effect of relatively little enrichment of hioenergetic elements from salmon carcas­ ses since the instigation of commercial fishing operations in comparison with the prefishing era when the entire virgin run escaped to the spawning grounds. Suggestions are made for future field testing of this hypothesis. In the development of the salmon fishery along the eastern perimeter of the Pacific Ocean, the most southern stocks were utilized first. As de­ mand increased and certain stocks declined, the fishery shifted northward until the runs of the entire southeastern Alaska and soon thereafter those of the western districts were exploited. The rapidity of growth of the salmon fishing in­ dustry in Alaska is astonishing. The firstcannery was built in southeastern Alaska at Klawak in 1878 (Rich and Ball, 1928), and only 6 years later exploratory fishing was conducted in Bristol Bay. The early Bristol Bay catch records show that, from 1884 to 1891, fishing was conducted only in Nushagak Bay (Figure 1). Four years later, salmon was harvested in the other watersheds of Bristol Bay, the Kvichak-Naknek, the Egegik,

La reproducción de la merluza en el Mar Argentino (Merlucciidae, Meluccius merluccius hubbsi) : 2. La reproducción de la merluza y su relación con otros aspectos biológicos de la especie

Abstract: The paper deals with the spawning cycle of the hake, Merluccius merluccius hubbsi in the fishing area of the Argentine fleet, SW Atlantic (35°- 46° L. S.: 53°- 63° L.W.; 30-160 fathoms depth). It was made on the basis of the weekly sampling of the commercial catch in the period January 1965 - March 1968. The results have been compared with those of the exploratory surveys made by the United Nations Fisheries Development Program (Republica Argentina - FAO). The histological study, which was made with 741 specimens, was most intensive in females than in males. The results have been compared with the sexual stage determinations of both sexes in the total samples during the period before mentioned. The conclusions are: 1. The analysis of the ovocytes frequency distributions showed a period of resting or slow recuperation (April - August) with a mode of 120 ~k and one of rapid transformation (October - December) from 120 μ till 830 ~k. After December it appears again the mode of 120 ~k which indicated the reserve stock. 2. The maturity factor shows in both sexes a period of low values , 0,52 to 2% (April - September) and, another with higher values (October - March). In the first period the values are concentrated, while in the second one a large dispersion is observed produced by the rapidity of the growth process of the gonads. It is more evident between November and December. 3. The liver weight variations, compared with the degree of ingestion and the values of the maturity factor, in time, demonstrated that: a) after two periods of abundant ingestion (March - April and October- November) there are two increases of the liver index; b) the increase of the Iiver index has a direct relation to the maturity factor; c) at the end of the summer season, when the values of the maturity factor decrease, those of the liver index are still high. This demonstrates that the hake does not arrive exhausted at the end of the spawning season and that a rapid recuperation for a new spawning by part of the stock is possible. 4. Females predominate in the samples during most of the year. In the period October - December, when sexual activation occurs, as it is demonstrated by the high values of the maturity factor, proportions are nearly 1 :1, and males at times are more numerous than females. 5. The analisys of the advaneed maturity stages, in relation to total length shows that in the hake, Iike in other fishes, the largest ones mature first. This applies for both sexes. 6. The study of the maturity factor values and the sexual stages of the samples allows the recognition of two spawning periods, the main one in summer (October - March) and another in winter (June - July). 7. Part of the summer spawners, with a rapid recuperation, should be able to spawn again in winter. This indicates that the hake population, acording to our samples, has two different possibilities of spawning. 8. After analysis of the frequency percentages composition of mature specimens it is concluded that during the summer season, when hake is fished in shallow waters and in a wide area (38°– 43° L.S.) the fleet is fishing on the spawning stocks. Some winter spawners specimens have been found at 37°- 38° L.S. and in waters of more than 100 fathoms depth. 9. A new maturity scale of seven stages is proposed, instead of the one of six stages now in use. The new added stage corresponds to the postspawners during its resting period.

A survey of the shrimp resources of Nigeria

Abstract: Previous planned resources surveys of the Nigerian coastal waters were performed with research vessels, gear and personnel not specialised for shrimp fishing. The results have, therefore, only indicated relative abundance of shrimps in the areas fished, rather than showing the absolute catches which a commercial fishing vessel in the area may expect to make. The present survey used two commercial shrimp trawlers together with their crews, who already had long experience of shrimp trawling both in the Nigerian shrimp grounds and elsewhere. Four shrimp species were caught: Penaeus duorarum, P. kerathurus, Parapeneopsis atlantica and Parapenaeus longirostris. Of these, P. duorarum, P. atlantica and P. longirostris are of commercial importance, P. duorarum being the most important. The distributions and concentrations of these 3 species are shown, together with the size distribution of P. duorarum, and the fish by-catch at each station. With the exception of the transect off the Nun Entrance, all transects sampled showed areas of high concentrations of P. duorarum, that is, 54 to 113 lbs (24 to 51 kg) of head-on shrimps per hour of trawling. The oceanographic conditions prevailing at the time of the survey were normal for the area. Records of previous shrimp landings from the area show a regular seasonal variation and the period of the survey to be one of lowest catches. The catch rates obtained in this survey are, therefore, the minimum which might be expected for the year. From a consideration of the operating costs of the type of shrimp trawler considered adequate for use in the area, it is found that the break-even shrimp catch is about 41 lbs (19 kg) of head-on per hour.

Investigations on the bottom conditions and the possibilities for marine prawn and fish trawling on the north and east coast of Ceylon

Abstract: The execution of this survey was decided upon by Swedevelop in agreement with the Sri Lanka Fisheries Corporation and was a part of the investigations and studies for a fishery project at Trincomalee which was carried out by Scandia Consult. The main purpose was to investigate the following aspects: bottom conditions, especially prawn trawling conditions; size of the potential prawn trawling catches; size and quality of the potential fish trawling catches; suitable sizes and types of boats and trawling gear; duration of trawl fishing season.

Oklahoma Commercial Fisheries Harvest Summary 1961-1969

Abstract: The OIdahoma Commercial Fishing HlII'Vest Survey, which bas P.'O~ded annual hlll'Vest data since 1957, was the source of the data on statewide com. mercial fishing annual harvest, by lake and by species, presented here for the period of 1961·1969. Wholesale fish prices received by Oklahoma commerci.l lishermen in 1968 an discussed and compared with those of 1958 and 1963. The Oklahoma Commercial Fishing Mar· estimates of catch per unit effon also varied

Institutional Changes and Development of the Fishing Industry in a Japanese Island Community

Abstract: The main focus of this study is placed on an analytical assessment of technological and institutional changes centering around the development of local fishing industry in the 1960's at Katsumoto-ura community, Iki Island, Nagasaki Prefecture, Japan. The technological change involved wide acceptance of innovative elements which have direct bearing upor modernization of fishing technique for local fishermer and fishing operations of the community as a whole. The impact of technological change has ultimate affected the marine ecology of this island. The institutional change, on the other hand, is concerned with development of a local fishing cooperative and its wider socio-economic implications, which resulted in an expansion of multi-functional activities affecting not only the technological sphere but other facets of local fishing industry as well. Contrary to much cited and readily observable technological change, which often leads to a notion of monistic technological determinism, this study is oriented...

Evaluation of Stocking Cutthroat Trout, Salmo clarki, in Munsel Lake, Oregon

Abstract: Natural mortality, emigration, and yield to anglers were assessed in 1962 for three releases of cutthroat trout (Salmo clarki) in Munsel Lake, Oregon. Stocked fish were caught emigrating from March 30, the start of trapping, to July 3. Natural mortality, 16 to 75%, was the dominant factor determining the number of fish available to anglers, and this mortality was greatest when anglers could not fish immediately after stocking. Yield of trout to anglers, estimated by creel census, indicated that after release fish were removed rapidly from the lake. Catch by anglers could be increased and catch per unit effort stabilized by liberating trout just before the fishing season and once or twice in the summer. This policy could reduce losses of fish from natural mortality and emigrations.

Geographical catch distribution of yellowfin and skipjack tuna in the Eastern Pacific Ocean, 1967-1970, and fleet and total catch statistics, 1962-1970

Abstract: ENGLISH: Logbook records of tuna vessels fishing in the eastern Pacific Ocean were used to prepare charts showing the distribution of yellowfin tuna and skipjack catches by i-degree area, by quarter of the year, and by gear, for the years 1967-1970. Recent changes in the geographical distribution of yellowfin catch are illustrated. Also given are annual catch statistics and the composition of the international tuna fishing fleets which operated in the Commission's Yellowfin Regulatory Area each year, 1962-1970. SPANISH: Los registros de los cuadernos de bitacora de los barcos pesqueros de atun en el Oceano Pacifico oriental se usaron para preparar graficos que presentan para los anos de 1967-1970, la distribucion de captura del atun aleta amarilla y barrilete por area de 1 grado, trimestre del ano y, por las artes. Se ilustran los recientes cambios en la distribucion geografica de la captura del atun aleta amarilla. Se presentan tambien las estadisticas de captura anual y la composicion de la flota internacional de pesca, que explota cada ano el Area Reglamentaria de la Comision, 1962-1970. (PDF contains 95 pages.)

Distribution and Movements of the Ribbon Fish in the East China Sea as Ascertained by Tagging Experiments in 1969

Abstract: The ribbon fish, Trichiurus lepturus LINNE, is an economically important species in the East China Sea and the Yellow Sea. The amount of its catch has reached 50, 000-56, 000 tons (1967-'69), which is equivalent to about 17% of the total catch of demersal fish. A total of 2, 561 fish out of the East China Sea population caught by angling were tagged and then released in the 329th, 330th, and 340th official blocks (Table 1, Fig. 2). Fifty-five individuals were recovered by the end of March, 1970, which gave a recovery rate of 2.1%. 45% of the total number of the recovered fish was actually recaptured within two months after they were released (Table 2). The comparison of the monthly distribution of the population density and the results of tagging indicated that the ribbon fish moved from the releasing areas toward the western seas off Quelpart Island and also up to 35°N (Fig. 6). Based on the present findings, it could presumably be suggested that there is considerable intermingling between the two populations of ribbon fish, the Yellow Sea population and the East China Sea population.