Browsing by Author "Bradley, Eddie"
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Item Biological Survey of the Commercial Shrimp and Associated Organisms of Area 20 in the Gulf of Mexico(Texas Game and Fish Commission Marine Laboratory, 1963) Compton, Henry; Bradley, EddieInformation in this report is based on data from 90 trawl samples producing a total of 4,602 brown shrimp, 882 white shrimp, 21 pink shrimp, 234 seabobs, 3,144 specimens of non-commercial shrimp of seven species, and 1,734 squid of two species. Browns migrating through the 2-15 fathom sampling area were most abundant in August. Whites showed scattered abundance peaks in April, July, September, and through the winter. The few pinks caught were most abundant in March-April. Seabobs were taken only in February and March. All four commercial shrimp suffered a definite abundance drop from the previous year. Two fo the common non-commercial species showed a corresponding decrease. Gulf environmental factors probably contributed to this drop in abundance. Sampling data again brought out the fact that in this area in depths under 15 fathoms the migrating brown population failed to reach individual sizes commensurate with most economic harvest during the period of abundance. The large whites in these waters were of commercial size.Item Biological Survey of the Commercial Shrimp and Associated Organisms of Area 20 in the Gulf of Mexico - Study of Texas Shrimp Populations(Texas Parks and Wildlife Department, 1964) Compton, Henry; Bradley, EddieInformation in this report is based on data from 85 trawl samples producing a total of 7,551 brown shrimp, 1,732 white shrimp, 123 pink shrimp, 9 seabobs, 3027 specimens of non-commercial shrimp of eight species, and 607 squid of two species. June, part of the closed season, was the month of heaviest movement of under-sized browns through the sampled area. During periods of abundance this species was below legal size. White shrimp were most abundant during the winter months; but economically too small for practical harvest in January, and probably during the latter part of December. Most of the few pinks caught were taken in February. With the exception of seabobs, the commercial species showed a large rise in abundance over the catch of 1962. Commercial landing statistics by unit effort showed a production abundance rise in 1963 in agreement with the findings of this report. Most of the non-commercial species of shrimp common to the area sampled increased in abundance in 1963. Hydrographic conditions, specifically salinity and temperature, remained practically constant with those found in 1962.Item Effects of Freshwater Inflows on Hydrological and Biological Parameters in the San Antonio Bay System, Texas(Texas Parks and Wildlife Department Coastal Fisheries Branch, 1975-08) Childress, Ray; Bradley, EddieBetween September 1971 and May 1974, semi-monthly samples of biologic, water quality, and meteorologic parameters were taken at various stations in the San Antonio Bay system of Texas. Hydrographic parameters concerning current movements were measured at selected intervals. The biological data and historical commercial fish and shellfish landings statistics were subjected to computerized analysis for possible correlations with simple and cumulative lag river inflow to the estuary and various hydrologic parameters. These analyses were performed in an effort to determine the importance of freshwater inflows, their effect on estuarine biota, and the quantity and quality of fresh water required by the system. Maps based on aerial photography were used to measure the dimensions of physical features within the system. Riverflow was the major source of fresh water and thereby exerted the most influence on the hydrologic parameters of the system. Rainfall supplied much less water than riverflow and was always exceeded by evaporation when averaged annually. Riverflow was also the main source of nutrients to the bay supplying an estimated daily average of 22 metric tons of phosphorus and 26 metric tons of nitrogen. Wind and floods were the main natural sources of turbidity. Oyster abundance increased at reefs in the lower bay area and decreased in the upper bay area when increased inflows caused reduction in salinity. When the amount of freshwater inflow for any single month prior to the month in question (simple lag inflow) was correlated with various catch data, the following relationships (significant at the 99% confidence level) were considered most germane to this study: white shrimp abundance correlated positively with simple lag river inflows of 1, 2, and 4 months; brown shrimp abundance correlated negatively with simple lag inflows of 2, 4, 6, and 8 months and positively with 12 months; bay anchovy abundance correlated positively at 1, 2, and 10 months; atlantic croaker abundance correlated positively at 1, 10, and 12 months. Juvenile blue crab abundance did not correlate at the 99% confidence level with simple lag inflows. Historical inflow and commercial landing data provided evidence that river inflows between 1.6 and 2.4 million acre feet per year, if adequate amounts are received in late spring, would optimize shellfish production in the San Antonio Bay systm. Analyses of the data were not conclusive enough to predict changes in finfish production due to changes in river inflow quantity.Item Migration Study on Brown Shrimp in Bay Area M-6 and Gulf Area 20(Texas Game and Fish Commission Marine Laboratory, 1962) Compton, Henry; Bradley, EddieShrimp stained June 5 through June 8 in Aransas Bay moved as predicted out of the bay and into the inshore Gulf. First returns from the Gulf were on July 5, a month after staining; however, at the rate of movement displayed through the bay and channels toward the Gulf, the first stained shrimp probably moved into the Gulf within three or four days of being released. The greatest distance moved was 59 miles in about 28 days. The fastest rate of movement was about 5 miles per day. A rough mileage rate, estimated from the first week's movement in the bays, was about two miles per day. Assuming brown shrimp of a mode of 80 mm, in June start moving to the Gulf at a certain speed, it can be predicted about when a certain group will enter the inshore waters which are closed for a certain period during the summer for conservation purposes. Knowledge of the rate and direction of movement will allow a more accurate regulation of this closed season.Item Population Studies of Fin-Fish on Artificial Shell Reefs in Corpus Christi Bay and the Upper Laguna Madre(Texas Parks and Wildlife Department, 1966) Bradley, EddieFour artificial reefs and four control stations were sampled each month with a modified otter trawl. Breakwater Reef, in Corpus Christi Bay, yielded more organisms than any other location sampled. Breakwater Reef Control Station was the second most productive area. Oso Reef Control Station yielded more than Oso Reef Station. Catches from the Laguna Madre were always small but the reefs were always more productive than the controls. Brown shrimp, Penaeus aztecus; white shrimp, P. setiferus; bay anchovy, Anchoa mitchilli; and Atlantic croaker, Micropogon undulatus, were the four most abundant species taken. Habitat appears to have been improved in the Laguna Madre but not in Corpus Christi Bay.Item Population Studies of the Blue Crabs of Gulf Area 20 - Studies of the Blue Crab Populations of the Texas Coast(Texas Parks and Wildlife Department, 1964) Compton, Henry; Bradley, EddieThe commercial blue crab, Callinectes sapidus, was not abundant in the inshore Gulf. The population consisted almost entirely of female crabs. The abundance peak occurred in June and July. In June, July, and August, 20 to 30 per cent of the females carried eggs. The little blue crab, Callinectes danae, was abundant in June and July, with a high percentage of ripe females during this period. In 1963, almost five times as many Gulf blue crabs were taken as in 1962. Of other crabs associated in the catches, the speckled crab, Arenaeus cribrarius, was most abundant.Item Population Studies of the Blue Crabs of Gulf Area 20 - Studies of the Blue Crab Populations of the Texas Coast(Texas Game and Fish Commission Marine Laboratory, 1963) Bradley, Eddie; Compton, HenryFor the year, 914 specimens were taken including 155 blue crabs, 630 Gulf blue crabs and 129 associated crabs. The blue crab was not abundant in the Gulf samples and, when found, was in shallow water. It had spawning peaks in March and August. The Gulf blue crab was more numerous and it was found in deeper water. Associated crabs in the area were not abundant. Of these crabs, Portunus gibbesii and Pagurus floridanus were the most numerous.Item Study of Post-larval Penaeid Shrimp Entering Aransas Bay - Study of Texas Shrimp Populations(Texas Game and Fish Commission Marine Laboratory, 1963) Compton, Henry; Bradley, EddiePreliminary steps were taken to set up types of sampling that would capture post-larval shrimp entering bay nursery grounds through the ship channel at Port Aransas, Texas. Due to the rather meager number of post-larval shrimp keys available, identification was accomplished only to genus. Sampling of the channel bottom on February 20 produced penaeids of 12 mm. length. Sampling on March 27, both in the main channel and in flats along an adjacent channel, produced 288 post-larval penaeids, the greatest number taken during the sampling period. Samples through November produced few shrimp, excluding 50 caught on October 2. Mysids, hypoplanktonic crustacea living generally on or near the bottom, were numerous in the samples and displayed somewhat the same abundance pattern found for post-larval shrimp. February water temperature averaged 15 degrees Celcius, rising to 18 degress Celcius in March, with a general warming trend through the sampling period to 28 degrees Celcius in October. On the shallow sand flat sampled, salinity rose from 22 ppt in March to just above 30 ppt in April and remained fairly constant thereafter. At the channel bottom salinity stayed above 30 ppt.Item Study of the Post-larval Penaeid Shrimp Entering Aransas Bay - Study of Texas Shrimp Populations(Texas Parks and Wildlife Department, 1964) Compton, Henry; Bradley, EddieThe first post-larval penaeids were taken in the Aransas Ship Channel bottom sample on February 19 at a depth of 8 mm, but not until after March 17 in mid-water channel and sand flat samples. They were most abundant in March and April. Sizes ranged from 6 to 14 millimeters. When shrimp Penaeus sp., were first taken in 1963, channel bottowm temperatures were 11.7 degrees C as compared to 15.8 degrees C at the same place and time in 1962. In 1963, 2.33 shrimp per unit effort were caught at that time; in 1962, 25.9 shrimp per unit effort were taken. After the middle of March, when post-larvae became abundant, temperatures were about 19 degrees C in both years. Associated organisms taken in large numbers were mysids, sergestids, crab larvae, and arrow worms. Mysids showed a spring abundance peak similar to penaeid post-larvae.Item Survey of Fish Found in Gulf Area 20 From 0-15 Fathoms - Analysis of Populations of Sports and Commercial Fin-Fish and of Factors Which Affect These Populations in the Coastal Bays of Texas(Texas Game and Fish Commission Marine Laboratory, 1963) Compton, Henry; Bradley, EddieThis report is based on information obtained from 90 trawl samples which produced a total of over 71,000 fish, weighing over 7,400 pounds. The fish samples in 1962 showed an increase in poundage of 90 per cent and an increase in abundance of 264 per cent over 1961. The best month for both weight and numbers was July, when there was an average of almost 200 pounds of fish per trawl. Many fish had depth preferences, with nine fathoms being favored by most.Item Survey of Larval and Post-Larval Fin-Fish in Aransas and Corpus Christi Channels and in the Inshore Gulf of Mexico - Analysis of Populations of Sports and Commercial Fin-Fish and of Factors Which Affect These Populations in the Coastal Bays of Texas(Texas Game and Fish Commission Marine Laboratory, 1963) Bradley, Eddie; Compton, HenryAdult fish spawn in the Gulf, with the young moving into the bays to mature. Most young fish remain close to the bottom. The period of cold or falling temperature was the spawning time for the fish studied.Item Survey of the Fishes found in Gulf Area 20 from 2-17 Fathoms and of Post-larval Fishes in Aransas Channel - Analysis of Populations of Sports and Commercial Fin-Fish and of Factors Which Affect These Populations in the Coastal Bays of Texas(Texas Parks and Wildlife Department, 1964) Compton, Henry; Bradley, EddieInformation in the adult fish report is based on data from 85 trawl samples producing an estimated total of 30,857 fishes of 94 species for an estimated total weight of 5,805 pounds. The two most abundant fishes were the croaker, Micropogon undulatus, and the Gulf sand trout, Cynoscion nothus. Zonation of species in the Gulf was found even within the narrow limits of job sampling. Many of the larger fish were taken in numbers and poundage commensurate with a possible commercial utilization. Post-larval fin-fish taken in Port Aransas Ship Channel had two peaks of abundance. One peak occurred in March and April and was due mainly to menhaden, Brevoortia sp., and pinfish, Lagodon rhomboides, 9 to 25 mm long. The next peak, in October and November, was composed of croaker 3 to 20 mm long. Post-larval menhaden and anchovies, Anchoa sp., were present in early spring, star drum, Stellifer lanceolatus, and croaker later in the year. Flatfish, mostly Paralichthys sp., were taken only on the bottom. Star drum were caught almost exclusively on the bottom. Croaker and pinfish showed some preference for moving at the bottom; anchovies, menhaden, and banded croaker, Larimus fasciatus, were taken mainly from levels above the bottom. By unit effort, the bottom beam trawl caught more fish than did the mid-water plankton net. No specific correlation between catch and temperature or catch and salinity was found.