Browsing by Author "Hofstetter, Robert P."
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Item Galveston Bay Oyster Studies, 1971(Texas Parks and Wildlife Department, 1971) Hofstetter, Robert P.; Texas Parks & Wildlife Coastal Fisheries Project Report 1971Galveston Bay oyster stocks were studied to detect changes which might affect the public reef oyster harvest. A mild winter and above normal salinity values favored increased disease (Labyrinthomyxa) incidence as well as increased predation from oyster drills (Thais) and stone crabs (Menippe). These factors resulted in annual death rates of 52% to 55% among older oysters groups. Oyster spat in an epidemic area were Labyrinthomyxa-infected by fall and suffered above normal mortality.Item Hydrographic and climatological data(Texas Game and Fish Commission, 1959) Hofstetter, Robert P.; Texas Game and Fish Commission Marine Lab Project Reports 1958-59Twenty stations were established in Galveston Bay to maintain records of hydrographic and climatological conditions as an aid in evaluating ecological changes in the bay.Item Oyster Investigation Quarterly Report - April 1, 1952 - June 30, 1952(Texas Game and Fish Commission, 1952-07) Hofstetter, Robert P.The primary purpose of this project is to determine the status of the major oyster reefs in Galveston Bay; their location, their condition and their productivity. In addition it is planned to secure the basic data necessary for an interpretation of the biological character of the bay, itself.Item Oyster Investigation Quarterly Report - January 1, 1952 - March 31, 1952(Texas Game and Fish Commission, 1952-04) Hofstetter, Robert P.This investigation in concerned with the collection and utilization of data relative to the oyster problem along the Texas coast.Item Oyster Investigation Quarterly Report - October 1, 1952 - December 31, 1952(Texas Game and Fish Commission, 1953-01) Hofstetter, Robert P.The purpose of this investigation is to formulate a program for the management of the oyster resources in Galveston Bay. The first step in the program, a survey of the condition and extent of the live oyster reefs, is now in progress. The scope of the work will be extended wherever possible to obtain those facts pertinent to an understanding of other problems in the bay.Item Oyster Investigation Quarterly Report - September 1, 1951 - December 31, 1951(Texas Game and Fish Commission, 1952-01) Hofstetter, Robert P.This investigation is concerned with (1) the collection of data relative to the oyster problem along the Texas coast, (2) the application of accumulated knowledge to the techniques of oyster cultivation and (3) the discovery and utilization of new methods of oyster culture.Item Oyster Mortality Studies along the Texas Coast during 1966(Texas Parks and Wildlife Department, 1966) Hofstetter, Robert P.; Texas Parks & Wildlife Coastal Fisheries Project Reports 1966Mortality studies among groups of seed and market oysters (Crassostrea virginica) were conducted in Aransas, San Antonio, Matagorda, and Galveston Bays. In general, death rates were low in winter, increased in spring, dropped in early summer and rose to late summer or early fall peaks.Item Oyster Studies Along the Texas Coast, 1968(Texas Parks and Wildlife Department, 1968) Hofstetter, Robert P.; Coastal Fisheries Project Reports 1968Oyster (Crassostrea virginica) studies showed death rates to be low in Aransas and Galveston Bays but relatively high in Matagorda Bay. Initial mortality in Matagorda Bay was associated with freshwater and siltation but subsequent summer deaths were associated with Labyrinthomyxa infection.Item Oyster studies along the Texas coast.(Texas Parks and Wildlife Department, 1967) Hofstetter, Robert P.; Coastal Fisheries project reportsOyster mortalities in Galveston, San Antonio, Aransas and South Bays were monitored through tray stations. Peak death rates among oyster stocks occurred during the spring in Aransas and South Bays, late summer in San Antonio Bay, and late spring in Galveston Bay. Mortality was severe in mid-coastal bays (Aransas and San Antonio) practically depleting the tray stocks. Spring mortality was moderate in South Bay, low in Galveston Bay.Item Oyster Studies, 1969(Texas Parks and Wildlife Department, 1969-70) Hofstetter, Robert P.; Coastal Fisheries project reportsOyster sampling was conducted in Galveston Bay, Texas. Monitoring of 1965, 1966, and 1967 year class oysters at two tray stations indicated a relatively low annual mortality rate of under 20%. Peak death rates, associated with Labyrinthomyxa infection, occurred in late summer. Moderate oyster spat setting occurred in the mid-bay area beginning in July. Survival was good and seed stock increased. Labyrinthomyxa marina infection among market oyster stocks remained below epidemic level and more oysters were available to the fishermen. Oystering was again centered in the mid-bay area and was judged to be relatively heavy. The harvest of 173,300 barrels was 22 percent higher than that of the previous season.Item Oyster Studies, 1970(Texas Parks and Wildlife Department, 1969-70) Hofstetter, Robert P.; Coastal Fisheries project reportsAnnual death rates among one to five year-old oyster stocks at tray stations in Galveston Bay ranged from 24 to 45%, representing an increase in mortality among the older stocks over that recorded in the previous year and an above average mortality for one-year old oysters. Labyrinthomyxa marina infections were primarily responsible.Item Study of the Oyster (Crassostrea virginica) Population Along the Texas Coast(Texas Parks and Wildlife Department, 1966) Hofstetter, Robert P.; Texas Parks & Wildlife Coastal Fisheries Project Reports 1965Reef sampling was continued in Galveston, Matagorda and San Antonio Bays to study trends in the oyster (Crassostrea Virginica) population. In Galveston a continued decline in spat and seed oyster stock occurred, with a lesser decline in market oyster stock. Matagorda Bay oyster stocks, which had suffered extensive mortality in 1964, showed only slight recovery. In San Antonio bay, the oyster population in the central bay, which had been decimated by disease in 1964, increased in abundance, but oyster stocks in the lower bay area diminished. Sring and late summer mortalities were common in all areas sampled. Generally, summer mortalities exceeded those in spring. Dermocystidium marinum infections were high in Galveston Bay but low, or negative, in other areas. The presence of ABO (Aransas Bay Organism) was suspected in Matagorda Bay and San Antonio Bay but was not confirmed. In spite of declining oyster stocks, the 1965-66 harvest set a new record of over four million pounds. As in past years, almost all of the harvest came from Galveston Bay.Item Study of the Oyster Population in the Galveston Bay Area - Survey of Oyster Populations and Associated Organisms(Texas Parks and Wildlife Department, 1965) Hofstetter, Robert P.; Texas Parks & Wildlife Coastal Fisheries Project Report 1964The sample abundance of oyster (Crassostrea virginica) spat decreased in 1963 as compared to 1962, and a further decline occurred in 1964. Seed oysters also declined in sample abundance during 1963 as a result of poor survival among the 1963 (and possibly 1962) oyster spat sets. The seed stock increased slightly during the fall 1964, indicating better survival of the 1964 oyster spat set. Market oysters were abundant in the samples during 1963 but decreased considerably in 1964.Item Study of the Oyster Population on Public Reefs in Galveston Bay during 1966(Texas Parks and Wildlife Department, 1966) Hofstetter, Robert P.; Texas Parks & Wildlife Coastal Fisheries Project Reports 1966Public reefs in Galveston Bay and East Bay were sampled monthly to determine seasonal changes in oyster (Crassostrea virginica) stocks.Item Summary of Oyster Studies Along the Texas Coast(Texas Parks and Wildlife Department, 1964) Hofstetter, Robert P.; Texas Parks & Wildlife Coastal Fisheries Project Reports 1963The intensity of 1963 oyster (Crassostrea virginica) spat set was generally less than that observed in 1962. The set appeared to be more abundant along the lower coast than on the upper coast. A decline in apparent abundance of year old seed stock was noted, beginning in late spring. Unlike 1962 little increase in the abundance of seed oysters occurred during the fall.Item Summary of Oyster Studies Along the Texas Coast - Survey of Oyster Populations and Associated Organisms(Texas Parks and Wildlife Department, 1965) Hofstetter, Robert P.; Texas Parks & Wildlife Coastal Fisheries Project Report 1964Both seed oyster Crassostrea virginica stock and market oyster stock continued to decline in Aransas, San Antonio, Matagorda, and Galveston Bays. Losses appeared to be most severe in the Aransas Bay area, diminishing up the coast to Galveston Bay. Much of the loss in the middle coast was attributed to Aransas Bay disease which affected young seed oysters as well as the older market oysters. The disease was found in 1963 in Aransas Bay and was apparently associated with the mortalities in San Antonio and Lavaca Bays. During 1964 the disease spread into Copano Bay, most of San Antonio Bay, Lavaca Bay, and Matagorda Bay. The organism responsible for Aransas Bay disease was identified by Dr. J.G. Mackin as an intre-cell organism similar to that associated with Malpeque Bay disease in Canadian waters. Sever mortalities in Tres Palacios Bay appeared to be caused by Dermocystidium marinum judging by the high infection incidence found in samples during the late summer. However, the catastrophic losses among seed oysters was more characteristic of Aransas Bay disease. In Galveston Bay Dermocstidium spread further up the bay than in 1963 and was assumed to be the primary cause of oyster mortalities. Tray studies at two stations showed an annual mortality rate of approximately 50 percent, both in 1963 and 1964. Most of the mortality at each station was due to Dermocystidium. Oyster production, in spite of high mortalities, set a new record during the 1964-65 season. Most of the harvest came from Galveston Bay where heavy fishing pressure compensated for the relatively low abundance of market oysters.Item Survey of Oyster Diseases in the Galveston Bay Area - Survey of Oyster Populations and Associated Organisms(Texas Parks and Wildlife Department, 1965) Hofstetter, Robert P.; Texas Parks & Wildlife Coastal Fisheries Project Report 1964Mortalities among tray-held oysters (Crassostrea virginica) were studied during a two year period at stations located on Switchover Reef and Hannah Reef. In 1963 mortalities at both stations showed similar patterns, increasing during the summer months (with peaks in August-September) and declining during the fall and winter. The summer mortalities were associated with high infections of Dermocystidium marinum. From March through December 1963 oysters at the Switchover station suffered a mortality of 52.6%. From April through December, 1963 a mortality of 42.2% occurred among the Hanna oysters.Item Survey of oyster reef populations(Texas Game and Fish Commission, 1959) Hofstetter, Robert P.; Texas Game and Fish Commission Marine Lab Project Reports 1958-59A study was conducted to determine the changes in the oyster populations on major reefs in Galveston Bay. The associated reef organisms with special emphasis on pests and predators were studied by way of collecting samples at a number of field stations.Item Survey of oyster spat setting and survival(Texas Game and Fish Commission, 1959) Hofstetter, Robert P.; Texas Game and Fish Commission Marine Lab Project Reports 1958-59Weekly oyster spatfall was determined by use of spat collectors placed at three stations in Galveston Bay.