The seasonal variations of sea level due to density variations in the Arabian Gulf and Gulf of Oman

From the distribution of oceanographic data (temperature and salinity) in both Arabian Gulf and Gulf of Oman, the steric components (thermal, haline and steric heights) are calculated for the upper 50m layer during different seasons. The analysis reveals relevant evidence, that temperature variations (thermal component) play a role in the fluctuations of sea level within the investigated area. The salinity variations (haline component) is only significant near the entrance. The sea level variations due to density (steric component) is low during winter and spring and high during summer and autumn. The steric height is always lower in the northern and central regions of Arabian Gulf and higher in eastern region of Arabian Gulf and in the Gulf of Oman, i.e. the surface water must flow from the Gulf of Oman to the Arabian Gulf. The steric sea level gradient around the Strait of Hormuz are 0.04 cm/km in winter, 0.04 cm/km in spring, and 0.025 cm/km in summer and 0.014 cm/km in autumn.

Biodiversity and socio-economic information of selected areas of Sri Lankan side of the Gulf of Mannar

Rapid biodiversity and socio-economic studies of the Gulf of Mannar were required as part of the process to propose the Sri Lankan side as a Biosphere Reserve. These included livelihoods; land use; infrastructure; biodiversity; agriculture; fisheries; archaeological and cultural significance; and development and environmental issues.

Population diversity studies of pharaoh cuttlefish (Sepia pharaonis) in the Persian Gulf and the Gulf of Oman

The pharaoh Cuttlefish (Sepia Pharaonis) is the most abundant species in the persian gulf and oman sea. The stock patterns of this species was studied conserning biological, morphological and electrophoretical aspects. In addition to measuring the biological patterns; 21 quantitative and qualitative factors were measured or counted. There tissues namely muscle, eye and liver were also used for further polyacrylamide electrophoresis analysis (SDS-Page method). The densitograms of protein bands of each tissue were prepared by Gel-Scanner and also the amount of bands' areas were estimated. The results of LSD test showed that tentacle length (TL), Tentacle club length (TCL) and TCL were indicative factors which they showed significant difference between male TL and female specimen of Bushehr and Balouchestan regions. Regarding to length and weight frequencies data the results indicated that males are always bigger than females and also, the cuttlefishes of the gulf of oman are bigger than persian gulf's samples. There were found a significant sample correlation (95%) between different quantitative parameters and the most correlation (0.963) was found to be between TL and TCL; whereas the less correlation (0.384) was observed between GL and LA3. However the gill length factor illustrated the less correlation with the other factors. The results of Cluster analysis for both sexes showed that the cuttlefishes of both studied regions belongs to seperate stocks. The electrophoretic experiments of proteins showed that the protein bands of the sample tissue of muscle and eye from both sampling areas revealed significant differences; whereas the tissue of liver wasn't recognized as an indicative tissue for population studies. Taking into consideration the findings of the present study including: (1) difference in spawning season, (2) results of dendrograms, (3) observed Significant differences in one-way analysis of variance (ANOVA) for morphometric measurements, (4) differences in body length and weight, (5) ecological variations of the persian gulf and oman sea, (6) as well as the results of electrophoresis of proteins have indicatend that: "The Pharaoh cuttlefishes of Bushehr and Balouchestan waters belong to two seperate stocks. Also, it is believed that each region has propably two different populations and more studies are needed to approve this result.

Preliminary estimates of cetacean abundance in the northern Gulf of Mexico, and of selected cetacean species in the U.S. Atlantic Exclusive Economic Zone from vessel surveys

The Southeast Fisheries Science Center (SEFSC) initiated annual, vessel-based visual sampling surveys of northern Gulf of Mexico marine mammals in 1990 and conducted a similar survey in U.S. Atlantic Exclusive Economic Zone (EEZ) waters from Miami, Florida, to Cape Hatteras, North Carolina, in 1992. The primary goal of these surveys was to meet Marine Mammal Protection Act requirements for estimating abundance and monitoring trends of marine mammal stocks in United States waters. The surveys were designed to collect: 1) marine mammal sighting data to estimate abundance and to determine distribution and diversity; and 2) environmental data to evaluate factors which may affect the distribution, abundance and diversity of marine mammals. The preliminary analyses for abundance estimation from the 1990-1993 surveys are presented in this report.

Estimates of cetacean abundance in the northern Gulf of Mexico from vessel surveys

The Southeast Fisheries Science Center (SEFSC) initiated annual, vessel-based visual sampling surveys of northern Gulf of Mexico marine mammals in 1990. The primary goal of these surveys was to meet Marine Mammal Protection Act requirements for estimating abundance and monitoring trends of marine mammal stocks in United States waters. The surveys were designed to collect: 1) marine mammal sighting data to estimate abundance and to determine distribution and diversity; and 2) environmental data to evaluate factors which may affect the distribution, abundance and diversity of marine mammals. The analyses for abundance estimation from the 1991-1994 surveys are presented in this report.

Morphometrics, length-weight relationship and condition of Rastrineobola argentea (Pellegrin 1904) in the Winam Gulf of Lake Victoria (Kenya)

Correlation between total length (TL), fork length (FL) and standard length (SL) of Raslrineobola argentea (pellegrin 1904) in the Winam Gulf of Lake Victoria indicate that FL = 0.92 TL - 0.74 and SL = 0.90 TL - 1.74. Length-weight relationship of log-transformed data shows that the slopes of the regression lines were 3.06 to 3.22 for juveniles, 2.70 to 3.05 for males and 3.24 to 3.71 for females. The slopes were significantly different between groups at at a =0.05. The Fulton's condition factor (K) was highest in December (1.019-1.073) and March/April (1.015-1.030) but lowest in June (1:00-1.025) for all stations. Significant differences between groups demands for the use of different growth models for juveniles, males and females especially for the von Bertalanffy growth equation which uses length-weight relationship. Observed cyclic viations in condition factor suggests two peak breeding seasons for this species in the Winam Gulf. The practical lmplications of these results in stock assessment using length-based fish stock assessment methods is briefly discussed.

Aspects of migration, size structure and mortality of juvenile Nile perch in the Mwanza Gulf of Lake Victoria

A detailed study of the early life of fishes forms one of the very important aspects with respect to recruitment mechanism and proper uneterstanding of the dynamics leading to sustainance of fish populations. It should be the central theme of the fisheries biologist and managers to extract the bilogical information relevant to the proper understanding of this part of the population. A number of studies in the Mwanza gulf and Lake Victoria have emphasized the need to monitor the fishery by conducting observations of stock size, migration, catch effort data and growth of big specimen (Acere 1981, Goudsward et al 1984, Asila. Ogari 1988 and Okemwa 1984). The present paper discusses the preliminary information on the size structure, mortality and migration of juvenile Nile perch. The long term objectives of the programme is aimed at describing the size structure, growth, mortality, recruitment pattern and population dynamics of the Nile perch up to 30 cm total length in the, Mwanza Gulf.

Diets of Steller sea lions (Eumetopias jubatus) in Southeast Alaska, 1993−1999

The diet of Steller sea lions (Eumetopias jubatus) was determined from 1494 scats (feces) collected at breeding (rookeries) and nonbreeding (haulout) sites in Southeast Alaska from 1993 to 1999. The most common prey of 61 species identified were walleye pollock (Theragra chalcogramma), Pacific herring (Clupea pallasii), Pacific sand lance (Ammodytes hexapterus), Pacific salmon (Salmonidae), arrowtooth flounder (Atheresthes stomias), rockfish (Sebastes spp.), skates (Rajidae), and cephalopods (squid and octopus). Steller sea lion diets at the three Southeast Alaska rookeries differed significantly from one another. The sea lions consumed the most diverse range of prey categories during summer, and the least diverse during fall. Diet was more diverse in Southeast Alaska during the 1990s than in any other region of Alaska (Gulf of Alaska and Aleutian Islands). Dietary differences between increasing and declining populations of Steller sea lions in Alaska correlate with rates of population change, and add credence to the view that diet may have played a role in the decline of sea lions in the Gulf of Alaska and Aleutian Islands.

Sizes of walleye pollock (Theragra chalcogramma) consumed by the eastern stock of Steller sea lions (Eumetopias jubatus) in Southeast Alaska from 1994 to 1999

Lengths of walleye pollock (Theragra chalcogramma) consumed by Steller sea lions (Eumetopias jubatus) were estimated by using allometric regressions applied to seven diagnostic cranial structures recovered from 531 scats collected in Southeast Alaska between 1994 and 1999. Only elements in good and fair condition were selected. Selected structural measurements were corrected for loss of size due to erosion by using experimentally derived condition-specific digestion correction factors. Correcting for digestion increased the estimated length of fish consumed by 23%, and the average mass of fish consumed by 88%. Mean corrected fork length (FL) of pollock consumed was 42.4 ±11.6 cm (range=10.0−78.1 cm, n=909). Adult pollock (FL>45.0 cm) occurred more frequently in scats collected from rookeries along the open ocean coastline of Southeast Alaska during June and July (74% adults, mean FL=48.4 cm) than they did in scats from haul-outs located in inside waters between October and May (51% adults, mean FL=38.4 cm). Overall, the contribution of juvenile pollock (≤20 cm) to the sea lion diet was insignificant; whereas adults contributed 44% to the diet by number and 74% by mass. On average, larger pollock were eaten in summer at rookeries throughout Southeast Alaska than at rookeries in the Gulf of Alaska and the Bering Sea. Overall it appears that Steller sea lions are capable of consuming a wide size range of pollock, and the bulk of fish fall between 20 and 60 cm. The use of cranial hard parts other than otoliths and the application of digestion correction factors are fundamental to correctly estimating the sizes of prey consumed by sea lions and determining the extent that these sizes overlap with the sizes of pollock caught by commercial fisheries.

Prey consumption of Steller sea lions (Eumetopias jubatus) off Alaska: How much prey do they require?

The effects of seasonal and regional differences in diet composition on the food requirements of Steller sea lions (Eumetopias jubatus) were estimated by using a bioenergetic model. The model considered differences in the energy density of the prey, and differences in digestive efficiency and the heat increment of feeding of different diets. The model predicted that Steller sea lions in southeast Alaska required 45–60% more food per day in early spring (March) than after the breeding season in late summer (August) because of seasonal changes in the energy density of the diets (along with seasonal changes in energy requirements). The southeast Alaska population, at 23,000 (±1660 SD) animals (all ages), consumed an estimated 140,000 (±27,800) t of prey in 1998. In contrast, we estimated that the 51,000 (±3680) animals making up the western Alaska population in the Gulf of Alaska and Aleutian Islands consumed just over twice this amount (303,000 [±57,500] t). In terms of biomass removed in 1998 from Alaskan waters, we estimated that Steller sea lions accounted for about 5% of the natural mortality of gadids (pollock and cod) and up to 75% of the natural mortality of hexagrammids (adult Atka mackerel). These two groups of species were consumed in higher amounts than any other. The predicted average daily food requirement per individual ranged from 16 (±2.8) to 20 (±3.6) kg (all ages combined). Per capita food requirements differed by as much as 24% between regions of Alaska depending on the relative amounts of low–energy-density prey (e.g. gadids) versus high–energy-density prey (e.g. forage fish and salmon) consumed. Estimated requirements were highest in regions where Steller sea lions consumed higher proportions of low–energy-density prey and experienced the highest rates of population decline

Diving behavior of immature Steller sea lions (Eumetopias jubatus)

Understanding the ontogenetic relationship between juvenile Steller sea lions (Eumetopias jubatus) and their foraging habitat is key to understanding their relationship to available prey and ultimately their survival. We summarize dive and movement data from 13 young-of-the-year (YOY) and 12 yearling Steller sea lions equipped with satellite dive recorders in the Gulf of Alaska and Aleutian Islands (n=18), and Washington (n=7) from 1994 to 2000. A total of 1413 d of transmission (x =56.5 d, range: 14.5–104.1 d) were received. We recorded 222,073 dives, which had a mean depth of 18.4 m (range of means: 5.8−67.9 m; SD=16.4). Alaska YOY dived for shorter periods and at shallower depths (mean depth=7.7 m, mean duration=0.8 min, mean maximum depth=25.7 m, and maximum depth=252 m) than Alaska yearlings (x =16.6 m, 0=1.1 min, x = 63.4 m, 288 m), whereas Washington yearlings dived the longest and deepest (mean depth=39.4 m, mean duration=1.8 min, mean maximum depth=144.5 m, and maximum depth=328 m). Mean distance for 564 measured trips was 16.6 km; for sea lions ≤10 months of age, trip distance (7.0 km) was significantly less than for those >10 months of age (24.6 km). Mean trip duration for 10 of the 25 sea lions was 12.1 h; for sea lions ≤10 months of age, trip duration was 7.5 h and 18.1 h for those >10 months of age. We identified three movements types: long-range trips (>15 km and >20 h), short-range trips (<15 km and <20 h) during which the animals left and returned to the same site, and transits to other haul-out sites. Long-range trips started around 9 months of age and occurred most frequently around the assumed time of weaning, whereas short-range trips happened almost daily (0.9 trips/day, n=426 trips). Transits began as early as 7 months of age, occurred more often after 9 months of age, and ranged between 6.5 and 454 km. The change in dive characteristics coincided with the assumed onset of weaning. These yearling sea lion movement patterns and dive characteristics suggest that immature Steller sea lions are as capable of making the same types of movements as adults.

The Annual Economic Survey of Federal Gulf Shrimp Permit Holders: Report on the Design, Implementation, and Descriptive Results for 2006

This technical memorandum documents the design, implementation, data preparation, and descriptive results for the 2006 Annual Economic Survey of Federal Gulf Shrimp Permit Holders. The data collection was designed by the NOAA Fisheries Southeast Fisheries Science Center Social Science Research Group to track the financial and economic status and performance by vessels holding a federal moratorium permit for harvesting shrimp in the Gulf of Mexico. A two page, self-administered mail survey collected total annual costs broken out into seven categories and auxiliary economic data. In May 2007, 580 vessels were randomly selected, stratified by state, from a preliminary population of 1,709 vessels with federal permits to shrimp in offshore waters of the Gulf of Mexico. The survey was implemented during the rest of 2007. After many reminder and verification phone calls, 509 surveys were deemed complete, for an ineligibility-adjusted response rate of 90.7%. The linking of each individual vessel’s cost data to its revenue data from a different data collection was imperfect, and hence the final number of observations used in the analyses is 484. Based on various measures and tests of validity throughout the technical memorandum, the quality of the data is high. The results are presented in a standardized table format, linking vessel characteristics and operations to simple balance sheet, cash flow, and income statements. In the text, results are discussed for the total fleet, the Gulf shrimp fleet, the active Gulf shrimp fleet, and the inactive Gulf shrimp fleet. Additional results for shrimp vessels grouped by state, by vessel characteristics, by landings volume, and by ownership structure are available in the appendices. The general conclusion of this report is that the financial and economic situation is bleak for the average vessels in most of the categories that were evaluated. With few exceptions, cash flow for the average vessel is positive while the net revenue from operations and the “profit” are negative. With negative net revenue from operations, the economic return for average shrimp vessels is less than zero. Only with the help of government payments does the average owner just about break even. In the short-term, this will discourage any new investments in the industry. The financial situation in 2006, especially if it endures over multiple years, also is economically unsustainable for the average established business. Vessels in the active and inactive Gulf shrimp fleet are, on average, 69 feet long, weigh 105 gross tons, are powered by 505 hp motor(s), and are 23 years old. Three-quarters of the vessels have steel hulls and 59% use a freezer for refrigeration. The average market value of these vessels was $175,149 in 2006, about a hundred-thousand dollars less than the average original purchase price. The outstanding loans averaged $91,955, leading to an average owner equity of $83,194. Based on the sample, 85% of the federally permitted Gulf shrimp fleet was actively shrimping in 2006. Of these 386 active Gulf shrimp vessels, just under half (46%) were owner-operated. On average, these vessels burned 52,931 gallons of fuel, landed 101,268 pounds of shrimp, and received $2.47 per pound of shrimp. Non-shrimp landings added less than 1% to cash flow, indicating that the federal Gulf shrimp fishery is very specialized. The average total cash outflow was $243,415 of which $108,775 was due to fuel expenses alone. The expenses for hired crew and captains were on average $54,866 which indicates the importance of the industry as a source of wage income. The resulting average net cash flow is $16,225 but has a large standard deviation. For the population of active Gulf shrimp vessels we can state with 95% certainty that the average net cash flow was between $9,500 and $23,000 in 2006. The median net cash flow was $11,843. Based on the income statement for active Gulf shrimp vessels, the average fixed costs accounted for just under a quarter of operating expenses (23.1%), labor costs for just over a quarter (25.3%), and the non-labor variable costs for just over half (51.6%). The fuel costs alone accounted for 42.9% of total operating expenses in 2006. It should be noted that the labor cost category in the income statement includes both the actual cash payments to hired labor and an estimate of the opportunity cost of owner-operators’ time spent as captain. The average labor contribution (as captain) of an owner-operator is estimated at about $19,800. The average net revenue from operations is negative $7,429, and is statistically different and less than zero in spite of a large standard deviation. The economic return to Gulf shrimping is negative 4%. Including non-operating activities, foremost an average government payment of $13,662, leads to an average loss before taxes of $907 for the vessel owners. The confidence interval of this value straddles zero, so we cannot reject, with 95% certainty, that the population average is zero. The average inactive Gulf shrimp vessel is generally of a smaller scale than the average active vessel. Inactive vessels are physically smaller, are valued much lower, and are less dependent on loans. Fixed costs account for nearly three quarters of the total operating expenses of $11,926, and only 6% of these vessels have hull insurance. With an average net cash flow of negative $7,537, the inactive Gulf shrimp fleet has a major liquidity problem. On average, net revenue from operations is negative $11,396, which amounts to a negative 15% economic return, and owners lose $9,381 on their vessels before taxes. To sustain such losses and especially to survive the negative cash flow, many of the owners must be subsidizing their shrimp vessels with the help of other income or wealth sources or are drawing down their equity. Active Gulf shrimp vessels in all states but Texas exhibited negative returns. The Alabama and Mississippi fleets have the highest assets (vessel values), on average, yet they generate zero cash flow and negative $32,224 net revenue from operations. Due to their high (loan) leverage ratio the negative 11% economic return is amplified into a negative 21% return on equity. In contrast, for Texas vessels, which actually have the highest leverage ratio among the states, a 1% economic return is amplified into a 13% return on equity. From a financial perspective, the average Florida and Louisiana vessels conform roughly to the overall average of the active Gulf shrimp fleet. It should be noted that these results are averages and hence hide the variation that clearly exists within all fleets and all categories. Although the financial situation for the average vessel is bleak, some vessels are profitable. (PDF contains 101 pages)

Incidental Catch of Marine Mammals by Foreign and Joint Venture Trawl Vessels in the U.S. EEZ of the North Pacific, 1973-88

During 1973-88, 3,661 marine mammals of 17 species were reported as incidental catch by U.S. fishery observers aboard foreign and joint venture trawl vessels in the U.S. Exclusive Economic Zone in the North Pacific Ocean and the Bering Sea. Northern sea lions (Eumetopias jubatus) accounted for 90% of the reported incidental mortality in the Gulf of Alaska and eastern Bering Sea. Nearly half of these sea lions were taken in trawl nets in the Shelikof Strait, Alaska, joint venture fishery during 1982-84. However, high incidental mortality rates (>25 sea lions per 10,000 metric tons of groundfish catch) also occurred in the foreign fisheries near Kodiak Island and in the Aleutian Islands area in earlier years. Estimated annual mortality of incidentally caught northern sea lions in Alaska declined from 1,000 to 2,000 animals per year during the early 1970s and 1982 to fewer than 100 animals in 1988. In the Bering Sea most sea lions incidentally caught were males, while in the Gulf of Alaska females were more frequently caught. Females may also have been dominant in the incidental catch of sea lions in the Aleutian Islands area, but age and sex composition data are limited. Incidental mortality of adult female sea lions by foreign trawl fisheries in these areas could have partially contributed to the reported declines in northern sea lion populations in Alaska during the 1970s, but it cannot alone account for the present decline in population size. (PDF file contains 64 pages.)

Results of abundance surveys of juvenile Atlantic and gulf Menhaden, Brevoortia tyrannus and B. patronus

The estuarine populations of juvenile Atlantic and gulf menhaden (Brevoortia tyrannus and B. patronus) were sampled during two-boat, surface-trawl, abundance surveys extensively conducted in the 1970s. Juvenile Atlantic menhaden were sampled in 39 estuarine streams along the U.S. Atlantic coast from northern Florida into Massachusetts. Juvenile gulf menhaden were sampled in 29 estuarine streams along the Gulf of Mexico from southeast Texas into western Florida. A stratified, two-stage, cluster sampling design was used. Annual estimates of relative juvenile abundance for each species of menhaden were obtained from catch-effort data from the surveys. There were no significant correlations, for either species, between the relative juvenile abundance estimates and fishery-dependent estimates of year-class strength. From 1972 to 1975, the relative abundance of juvenile Atlantic menhaden in north Atlantic estuaries decreased to near zero. (PDF file contains 22 pages.)

Socio-economic vulnerability of African Americans in the Gulf coast counties

The states bordering the Gulf of Mexico i.e. Texas, Louisiana, Mississippi, Alabama, and Florida have been historically devastated by hurricanes and tropical storms. A large number of African Americans live in these southern Gulf States which have high percentages of minorities in terms of total population. According to the U.S. Census, the total black population in the United States is about 40.7 million and about one-fourth of them live in these five Gulf States (U.S. Census, 2008). As evidenced from Hurricane Katrina and other major hurricanes, lowincome and under-served communities are usually the hardest hit during these disasters. The aim of this study is to identify and visualize socio-economic vulnerability of the African American population at the county level living in the hurricane risk areas of these five Gulf States. (PDF contains 5 pages)