963 resultados para CPG (Central pattern generator)


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Marine reserves, often referred to as no-take MPAs, are defined as areas within which human activities that can result in the removal or alteration of biotic and abiotic components of an ecosystem are prohibited or greatly restricted (NRC 2001). Activities typically curtailed within a marine reserve are extraction of organisms (e.g., commercial and recreational fishing, kelp harvesting, commercial collecting), mariculture, and those activities that can alter oceanographic or geologic attributes of the habitat (e.g., mining, shore-based industrial-related intake and discharges of seawater and effluent). Usually, marine reserves are established to conserve biodiversity or enhance nearby fishery resources. Thus, goals and objectives of marine reserves can be inferred, even if they are not specifically articulated at the time of reserve formation. In this report, we review information about the effectiveness of the three marine reserves in the Monterey Bay National Marine Sanctuary (Hopkins Marine Life Refuge, Point Lobos Ecological Reserve, Big Creek Ecological Reserve), and the one in the Channel Islands National Marine Sanctuary (the natural area on the north side of East Anacapa Island). Our efforts to objectively evaluate reserves in Central California relative to reserve theory were greatly hampered for four primary reasons; (1) few of the existing marine reserves were created with clearly articulated goals or objectives, (2) relatively few studies of the ecological consequences of existing reserves have been conducted, (3) no studies to date encompass the spatial and temporal scope needed to identify ecosystem-wide effects of reserve protection, and (4) there are almost no studies that describe the social and economic consequences of existing reserves. To overcome these obstacles, we used several methods to evaluate the effectiveness of subtidal marine reserves in Central California. We first conducted a literature review to find out what research has been conducted in all marine reserves in Central California (Appendix 1). We then reviewed the scientific literature that relates to marine reserve theory to help define criteria to use as benchmarks for evaluation. A recent National Research Council (2001) report summarized expected reserve benefits and provided the criteria we used for evaluation of effectiveness. The next step was to identify the research projects in this region that collected information in a way that enabled us to evaluate reserve theory relative to marine reserves in Central California. Chapters 1-4 in this report provide summaries of those research projects. Contained within these chapters are evaluations of reserve effectiveness for meeting specific objectives. As few studies exist that pertain to reserve theory in Central California, we reviewed studies of marine reserves in other temperate and tropical ecosystems to determine if there were lessons to be learned from other parts of the world (Chapter 5). We also included a discussion of social and economic considerations germane to the public policy decision-making processes associated with marine reserves (Chapter 6). After reviewing all of these resources, we provided a summary of the ecological benefits that could be expected from existing reserves in Central California. The summary is presented in Part II of this report. (PDF contains 133 pages.)

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In Central California, and elsewhere around the world, a great deal of discussion is occurring about the use of marine protected areas (MPAs) as a tool to help manage marine resources. This discussion is taking place because there is growing evidence that humans have depleted marine resources in many parts of the world, often despite strong regulatory efforts. Moreover, there is also mounting evidence that the degradation of marine resources began long ago, and we do not fully realize how much humans have altered “natural” environments. This uncertainty has led people to discuss the use of MPAs as a precautionary tool to prevent depletion or extinction of marine resources, and as a means of redressing past damages. The discussion about the use of marine reserves is increasing in intensity in California because several resource management agencies are considering reserves as they create or revise management plans. Often, the discussions surrounding this important public policy debate lead to questions about the biological or ecological value of existing marine protected areas. More than 100 MPAs exist along the coast of California. Many of these were established arbitrarily and lack specific purposes. Some California marine protected areas also have co-occurring or overlapping boundaries, have conflicting designations for use, and have conflicting rules and regulations. Because few of the existing marine protected areas have clearly articulated goals or objectives, however, it is difficult or impossible to evaluate their ecological effectiveness. (PDF contains 18 pages.)

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The broad scale features in the horizontal, vertical, and seasonal distribution of phytoplankton chlorophyll a on the northeast U.S. continental shelf are described based on 57,088 measurements made during 78 oceanographic surveys from 1977 through 1988. Highest mean water column chlorophyll concentration (Chlw,) is usually observed in nearshore areas adjacent to the mouths of the estuaries in the Middle Atlantic Bight (MAB), over the shallow water on Georges Bank, and a small area sampled along the southeast edge of Nantucket Shoals. Lowest Chlw «0.125 ug l-1) is usually restricted to the most seaward stations sampled along the shelf-break and the central deep waters in the Gulf of Maine. There is at least a twofold seasonal variation in phytoplankton biomass in all areas, with highest phytoplankton concentrations (m3) and highest integrated standing stocks (m2) occurring during the winter-spring (WS) bloom, and the lowest during summer, when vertical density stratification is maximal. In most regions, a secondary phytoplankton biomass pulse is evident during convective destratification in fall, usually in October. Fall bloom in some areas of Georges Bank approaches the magnitude of the WS-bloom, but Georges Bank and Middle Atlantic Bight fall blooms are clearly subordinate to WS-blooms. Measurements of chlorophyll in two size-fractions of the phytoplankton, netplankton (>20 um) and nanoplankton «20 um), revealed that the smaller nanoplankton are responsible for most of the phytoplankton biomass on the northeast U.S. shelf. Netplankton tend to be more abundant in nearshore areas of the MAB and shallow water on Georges Bank, where chlorophyll a is usually high; nanoplankton dominate deeper water at the shelf-break and deep water in the Gulf of Maine, where Chlw is usually low. As a general rule, the percent of phytoplankton in the netplankton size-fraction increases with increasing depth below surface and decreases proceeding offshore. There are distinct seasonal and regional patterns in the vertical distribution of chlorophyll a and percent netplankton, as revealed in composite vertical profiles of chlorophyll a constructed for 11 layers of the water column. Subsurface chlorophyll a maxima are ubiquitous during summer in stratified water. Chlorophyll a in the subsurface maximum layer is generally 2-8 times the concentration in the overlying and underlying water and approaches 50 to 75% of the levels observed in surface water during WS-bloom. The distribution of the ratio of the subsurface maximum chlorophyll a to surface chlorophyll a (SSR) during summer parallels the shelfwide pattern for stability, indexed as the difference in density (sigma-t) between 40 m and surface (stability 40. The weakest stability and lowest SSR's are found in shallow tidally-mixed water on Georges Bank; the greatest stability and highest SSR's (8-12:1) are along the mid and outer MAB shelf, over the winter residual water known as the "cold band." On Georges Bank, the distribution of SSR and the stability40 are roughly congruent with the pattern for maximum surface tidal current velocity, with values above 50 cms-1 defining SSR's less than 2:1 and the well-mixed area. Physical factors (bathymetry, vertical mixing by strong tidal currents, and seasonal and regional differences in the intensity and duration of vertical stratification) appear to explain much of the variability in phytoplankton chlorophyll a throughout this ecosystem. (PDF file contains 126 pages.)

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During June 1974 the California Department of Fish and Game, in cooperation with the Sea Grant program at Moss Landing Marine Laboratories, conducted an exploratory fishing cruise that extended from La Jolla to Santa Cruz and included the Channel Islands, concentrating on inshore waters. The cruise was preliminary to the initiation of a major program of squid research and had six objectives: 1) To gather samples of market squid (Lo1igo opa1escens) for population, growth, aging and food chain studies. 2) To locate potential new fishing grounds. 3) To investigate methods for determining spawning intensity. 4) To gather data on oceanographic parameters of the spawning grounds. 5) To make incidental collections as requested by other investigators. 6) To familiarize Sea Grant personnel with the capabilities of the Department's largest research vessel, ALASKA, with respect to squid. Especially good weather and oceanographic conditions persisting throughout the cruise enabled us to make 66 night1ight stations, 17 midwater trawls and eight bottom trawls. Fishable concentrations of squid were discovered in the areas between Cape San Martin and Partington Point, between Pfeiffer Point and Point Sur, and in Carmel Bay, heretofore unfished. Squid spawning off Santa Cruz Island was observed utilizing an underwater observation chamber aboard the vessel. Mating and feeding behavior were observed in shipboard aquaria. PDF contains 28 pages)

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In this report, we present oceanographic results from VERTEX 3 Particle Interceptor Trap (PIT) experiment conducted off the western-coast of Mexico during October to November 1982. The oceanographic data presented here were obtained during three cruise legs by Moss Landing Marine Laboratory scientists aboard R/V Cayuse while the detailed chemical studies were done by other scientists aboard R/V Wecoma. Only the oceanographic data will be presented in this report. (PDF contains 82 pages)

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This report covers the 37th annual inventory of chinook salman, Oncorhynchus tshawytscha, spawner populations in the Sacramento-San Joaquin River system.-It is a compilation of reports estimating the fall-, winter-, late-fall-, and spring-run salmon spawner populations for streams which were surveyed. Estimates were made from counts of fish entering hatcheries and migrating past dams, froro surveys of dead and live fish and redds on spawning areas, and from aerial counts. The estimated 1989 total escapement of chinook salmon in the Central Valley was 205,990 fish. This total consisted of 181,864 fall-, 12,171 spring-, 539 winter-, and 11,416 late-fall-run spawners. All of the spring-, late-fall-, and winter-run salmon were estimated to be in the Sacramento River system, while 3,493 fish of the fall run were in the San Joaquin River system. Due to decreases of spawner populations in most Central Valley tributaries, the total 1989 salmon stock was 32% lower than in 1988; however, late-fall salmon in the upper Sacramento River had a run size similar to that of 1988. The winter run in the mainstem Sacramento River was at a record low level. (PDF contains 44 pages.)

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In 1992 and 1993, researchers from the National Marine Mammal Laboratory initiated photo-identification studies on Alaskan killer whales, Orcinus orca. Waters from Kodiak Island west to the central and eastern Aleutian Islands and southeastern Bering Sea were surveyed. A total of 289 individual whales were identified. A photographic record of the whales encountered during these surveys is presented. When photographs of the 289 individual whales were compared among various regions in Alaska (Prince William Sound and Southeast Alaska) and areas outside Alaska (British Columbia, Washington, and California), 11 matches were found. The count is conservative because the 1992 and 1993 surveys were limited in geographical range, restricted to summer periods, and whales may have been missed along the survey trackline. Future research incorporating both photoidentification studies and line transect surveys will provide reliable abundance estimates of Alaskan killer whales. (PDF file contains 58 pages.)

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Over 100 molluscan species are landed in Mexico. About 30% are harvested on the Pacific coast and 70% on the Atlantic coast. Clams, scallops, and squid predominate on the Pacific coast (abalone, limpets, and mussels are landed there exclusively). Conchs and oysters predominate on the Atlantic coast. In 1988, some 95,000 metric tons (t) of mollusks were landed, with a value of $33 million. Mollusks were used extensively in prehispanic Mexico as food, tools, and jewelry. Their use as food and jewelry continues. Except in the States of Baja California and Baja California Sur, where abalone, clams, and scallops provide fishermen with year-round employment, mollusk fishing is done part time. On both the Pacific and Atlantic coasts, many fishermen are nomads, harvesting mollusks wherever they find abundant stocks. Upon finding such beds, they build camps, begin harvesting, and continue until the mollusks become so scarce that it no longer pays to continue. They then look for productive beds in other areas and rebuild their camps. Fishermen harvest abalones, mussels, scallops, and clams by free-diving and using scuba and hooka. Landings of clams and cockles have been growing, and 22,000 t were landed in 1988. Fishermen harvest intertidal clams by hand at wading depths, finding them with their feet. In waters up to 5 m, they harvest them by free-diving. In deeper water, they use scuba and hooka. Many species of gastropods have commercial importance on both coasts. All species with a large detachable muscle are sold as scallops. On the Pacific coast, hatchery culture of oysters prevails. Oyster culture in Atlantic coast lagoons began in the 1950's, when beds were enhanced by spreading shells as cultch for spat. (PDF file contains 228 pages.)

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This three-volume monograph represents the first major attempt in over a century to provide, on regional bases, broad surveys of the history, present condition, and future of the important shellfisheries of North and Central America and Europe. It was about 100 years ago that Ernest Ingersoll wrote extensively about several molluscan fisheries of North America (1881, 1887) and about 100 years ago that Bashford Dean wrote comprehensively about methods of oyster culture in Europe (1893). Since those were published, several reports, books, and pamphlets have been written about the biology and management of individual species or groups ofclosely related mollusk species (Galtsoff, 1964; Korringa, 1976 a, b, c; Lutz, 1980; Manzi and Castagna, 1989; Shumway, 1991). However, nothing has been written during the past century that is comparable to the approach used by Ingersoll in describing the molluscan fisheries as they existed in his day in North America or, for that matter, in Europe. (PDF file contains 224 pages.)

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This report presents meristic data for nearly all of the known species of Sebasles. Rudimentary caudal ray counts tend to be higher in more active species. The number of caudal rays supported by the hypurals is consistently 14, whereas the number of branched caudal rays varies between 11 and 13. Vertebral counts and most fin-ray counts tend to be lower in species or populations in warmer latitudes, except for pectoral ray counts which tend to have an opposite geographic pattern. On the basis of the small magnitude of meristic and morphometric differences and the lack of other differences between northern and southern samples of "Sebasles caurinus," Sebaslichlhys vexillaris Jordan and Gilbert is regarded as a junior synonym of Sebasles caurinus Richardson. The patterns of bilateral variation in paired meristics are analyzed and their mechanism discussed. The frequency distribution of pectoral ray counts in their right-left combination is shown to be useful in species separation. No association was found between any combination of two meristic features in any species. The author proposes that intrasample associations between meristic features are evidence of sampling heterogeneity. (PDF file contains 21 pages.)

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Ponencia presentada en el 10th World Congress on Computational Mechanics (WCCM 2012), Sao Paulo (Brazil).Publicados los abstracts en documento con ISBN: 978-85-86686-69-6.