960 research outputs found

    A multidisciplinary study of the scyphozoan jellyfishes of lower Chesapeake Bay, 1 July 1969 - 31 March 1970

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    This report covers the activities.through the end of the project agreement period that terminated 30 April 1970. The last annual report submitted covered the period l July 1968 - 30 June 1969. A detailed semi-annual report that covered the period l July 1969 - 31 December 1969 was submitted in early February 1970. Therefore, only the last four months of the project period have not been covered by previous reports. The information presented here is based on jellyfish research conducted at the Virginia Institute of Marine Science , during路 the interval 路between l January 1970 and.31 March 1970. This report outlines the progress achieved in various biochemical, developmental, ecological, physiological, and taxonomic studies on scyphozoan polyps and medusae

    A multidisciplinary study of the scyphozoan jellyfishes of lower Chesapeake Bay, 1 July 1968 - 30 June 1969

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    At the beginning of the fiscal year covered by this report the scope of the present study was restricted to an ecological consideration of the jellyfish, Chrysaora quinquecirrha. During the winter of 1968 the project proposal was amended broadly to include physiological, biochemical and developmental aspects and the taxonomic base was expanded to include the clover leaf jellyfish Aurelia aurita and the lions mane jellyfish Cyanea capillata. It was not possible to initiate those physiological and developmental aspects that required the medusae of the two summer species until the last month covered by this report. However some activities on all phases were begun during the past winter and spring. In ) addition, these months were used effectively to recruit an excellent staff and to acquire and assemble the necessary equipment. At the end of the fiscal year all personnel had joined the staff and all phases were underway

    A multidisciplinary study of the scyphozoan jellyfishes of lower Chesapeake Bay, 1 April 1968 - 31 March 1971: Completion Report

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    This document will constitute the completion report for contract No. 14-17-0007-961 (as amended) entitled 11A Multidisciplinary Study of the Scyphozoan Jellyfishes of Lower Chesapeake Bay. 11 The contract period covered a time-span of approximately three years. Two annual reports and one semi-annual report containing details of progress have been submitted prior to this completion report. The first portion of this document will consist of a brief summary of accomplishments for the entire contract period. The second portion will contain a rather detailed statement of progress for the final year. This latter information has not been reported previously

    A review of the population structure of yellowfin tuna, Thunnus albacares, in the Eastern Pacific Ocean

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    ENGLISH: Since its inception in 1950 by agreement between the Republic of Costa Rica and the United States of America, the Inter-American Tropical Tuna Commission has been engaged in studies of the biology, ecology and population dynamics of yellowfin tuna in the eastern Pacific Ocean. Prime consideration has been given to the evaluation of the effects of fishing pressure on the yellowfin tuna in this area in order to estimate the maximum sustainable yield. A portion of the eastern Pacific has been defined by the Inter-American Tropical Tuna Commission (1963) as a regulatory area for yellowfin tuna (Figure 1). SPANISH: Desde su incepci贸n en 1950, por un acuerdo entre la Rep煤blica de Costa Rica y los Estados Unidos de Am茅rica, la Comisi贸n Interamericana del At煤n Tropical ha estado ocupada en los estudios de la biolog铆a, ecolog铆a y din谩mica de las poblaciones del at煤n aleta amarilla en el Oc茅ano Pac铆fico Oriental. Se consider贸 primariamente la evaluaci贸n de los efectos de la presi贸n de la pesquer铆a sobre el at煤n aleta amarilla en esta 谩rea, para poder estimar el rendimiento m谩ximo sostenible. Una parte del Pac铆fico Oriental ha sido definida por la Comisi贸n Interamericana del At煤n Tropical (1963), como 谩rea de reglamentaci贸n del at煤n aleta amarilla (Figura 1). (PDF contains 60 pages.

    Growth And Survival Of Striped Bass And Striped Bass X White Perch Hybrids

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    Experiments comparing growth and survival of striped bass (Morvne saxatilis) and striped bass female X white perch (M. americana) male hybrids indicated the hybrids were hardier than striped bass under the same experimental conditions. Striped bass exhibited health problems and resulting mortality which were not evident in the hybrids. Overall survival of striped bass in 2 replicate experiments was 42.5% after II months. whereas that of the hybrids was 84.2%. Striped bass and hybrid growth patterns were similar, but striped bass grew somewhat more rapidly than the latter. Mean specific (instantaneous) growth rates were roughly similar throughout the study. with the major differences occurring during the first 4 months. At 17 months of age the mean hybrid fork length was 227.50101 (range. 167 to 282 0101). This length was approximately equivalent to that of wild populations of white perch with 4 to 8 annuli and to that of mid-Atlantic striped bass with 2 annuli, but was substantially less than that of fresh-water and more southern populations. Hybrid length-weight equations were intermediate between those of striped bass and white perch. Salinity experiments demonstrated that both small (mean fork length, 43 mm) and large (mean fork length. 279 mm) hybrids can survive and grow for indefinite periods at salinities of 18 to 25 0/00 with no signs of stress. We believe that the hybrid may be suitable as a supplement to natural populations of striped bass and white perch in estuaries.https://scholarworks.wm.edu/vimsbooks/1113/thumbnail.jp

    Comparative strength of the 1966 year class of striped bass, Roccus saxatilis (Walbaum), in three Virginia rivers

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    The age composition, as determined from scale impressions, of striped bass stocks in the James, York, and Rappahannock Rivers during the period June 1967 - March 1968 indicates a relative deficiency of the 1966 year class in the James River. Similar results are shown in samples from non-selective gear (pound nets, fyke nets), selective gear (gill nets, haul seines, hook-and-line), and routine surveys using a 30-foot semi-balloon trawl.https://scholarworks.wm.edu/vimsbooks/1133/thumbnail.jp

    Seasonal availability and distribution of benthic fishes of Chesapeake Bight

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    In considering the potential for expanding the Middle Atlantic fishery, Virginia Institute of Marine Science estimated the seasonal distribution and availability of benthic fishes on the 15,000 square miles of continental shelf between Cape Hatteras and Cape May. The survey, which started in the winter of 1966 and continued through the winter of 1968, was conducted in two phases. The 路work in 1966 路was devoted to determining the seasonal distribution of the various kinds of fishes, especially those which appeared to be under-utilized. For.this work a 45-foot semi-balloon shrimp trawl was employed to make 295 tows which were divided among the four seasons. In the second phase, conducted in 1967 and 1968, the objcctive路was to estimate the quantity of fish potentially available to trawlers, should a market be developed
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