Aquatic Commons
(22,210 recursos)
The Aquatic Commons is a thematic digital repository covering the natural marine, estuarine /brackish and fresh water environments . It includes all aspects of the science, technology, management and conservation of these environments, their organisms and resources, and the economic, sociological and legal aspects.
Subject = Conservation
Mostrando recursos 61 - 80 de 975
61.
Differences in Dolphin Mortality Rates in Night and Day Sets for the U.S. Eastern Tropical Pacific Tuna Purse Seine Fishery - Coan, Jr. , Atilio L.; Wallace, Kenneth E.; Jackson , Alan R.
Because dolphins sometimes travel with yellowfin tuna, Thunnus albacares, in the eastern tropical Pacific (ETP), purse seiners use the dolphins to locate and capture tuna schools. During the process of setting the purse seine nets, dolphins often become entangled and drown before they can be released. Data for the U.S. purse seine fleet in the ETP during 1979-88 show that dolphin mortality rates in sets made during the night are higher than mortality rates in sets made during the day. Even with efforts to reduce nightset mortality rates through the use of high intensity floodlights, night set mortality rates remain...
62.
The National Marine Fisheries Service Habitat Conservation
Efforts in Louisiana, 1980 Through 1990 - Hartman, Richard D.; Ruebsamen, Rickey N.; Jones, Peggy M.; Koellen, Jan L.
Data quantifying various aspects of the Corps of Engineers wetland regulatory program in Louisiana from 1980 through 1990 are presented. The National Marine Fisheries Service (NMFS) habitat conservation efforts for this time period are described and averages involved delineated. From 1980 through 1990, NMFS reviewed 14,259 public notices to dredge, fill, or impound wetlands in Louisiana and provided recommendations to the Corps on 962 projects which proposed to impact over 600,000 acres of tidally influenced wetlands. NMFS recommended that impacts to about 279,000 acres be avoided and that more than 150,000 acres of compensatory mitigation be provided. During this period,...
63.
Sea Turtle Observations at Explosive Removals of Energy Structures - Gitschlag, Gregg R.; Herczeg, Bryan A.
Observers were placed at offshore sites to monitor and protect sea turtles during explosive removals of oil and gas structures in the Gulf of Mexico off Louisiana and Texas. Data collected during more than 6,500 hours of monitoring at 106 structure removals in 1992 provided information on sea turtle distribution. Eighteen individuals were observed including 10 loggerheads, 2 leatherbacks, 1 hawksbill, and 5 unidentified sea turtles. The observation rate (individuals per monitoring hour) of sea turtles was about 30 times higher during aerial surveys than during day or night suiface surveys.
64.
Trawling Operations and South African (Cape) Fur Seals, Arctocephalus pusillus pusillus - Wickens, Patti A.; Sims, Peter F.
South African (Cape) fur seals, Arctocephalus pusillus pusillus, interact with the South African trawl fisheries-offshore demersal, inshore demersal, and midwater fisheries. These interactions take thef ollowing forms: Seals take or damage netted fish, on particular vessels they become caught in the propeller, seals drown in the nets, live seals come aboard and may be killed. Except in specific cases of seals damaging particular trawler propellers, interactions result in little cost to the offshore and midwater trawl fisheries. For the inshore fishery, seals damage fish in the net at an estimated cost in excess of R69, 728 (US$18,827) per year, but...
65.
The Origin, Evolution, and Demise of the U.S. Sea Turtle Fisheries - Witzell , W. N.
Fishing was America's first industry, and turtling played an important role in the nation's developing fisheries. However, before the European settlers arrived in the New World, Native Americans had already developed spiritual and gastronomic relationships with sea turtles. There are indications that ancient Florida tribes had eaten sea turtles and then placed the skulls in burial mounds (Johnson, 1952).
66.
The Threatened Status of Steller Sea Lions, Eumetopias jubatus, under the Endangered Species Act: Effects on Alaska Groundfish Fisheries Management - Fritz, Lowell W.; Ferrero, Richard C.; Berg , Ronald J.
In April 1990, the Steller sea lion, Eumetopias jubatus, was listed as threatened under the U.S. Endangered Species Act by emergency action. Competitive interactions with the billion-dollar Alaska commercial groundfish fisheries have been suggested as one of the possible contributing factors to the Steller sea lion population decline. Since the listing, fisheries managers have attempted to address the potential impacts of the groundfish fisheries on Steller sea lion recovery. In this paper, we review pertinent Federal legislation, biological information on the Steller sea lion decline, changes in the Alaska trawl fishery for walleye pollock, Theragra chalcogramma, since the late 1970's,...
67.
An Observed Entanglement of Lagenorhynchus obliquidens in the High Seas Driftnet Area in the North Pacific - Mizroch, S. A.; Hutchinson, C.
In August, 1991, an entanglement event was observed in the High Seas Driftnet area in the North Pacific. This description of an entanglement of Lagenorhynchus obliquidens is the first such documented report of dolphins entangling while bowriding. One of the entangled dolphins was rescued from the driftnet.
68.
Trends and Potential Interactions Between Pinnipeds and Fisheries of New England and the U.S. West Coast - Baraff, Lisa S.; Loughlin, Thomas R.
Long-term trends in the abundance and distribution of several pinniped species and commercially important fisheries of New England and the contiguous U.S. west coast are reviewed, and their actual and potential interactions discussed. Emphasis is on biological interactions or competition. The pinnipeds include the western North Atlantic stock of harbor seals, Phoca vitulina concolor; western North Atlantic gray seals, Halochoerus grypus; the U.S. stock of California sea lions, Zalophus californianus californianus; the eastern stock of Steller sea lions, Eumetopias jubatus; and Pacific harbor seals, Phoca vitulina richardii. Fisheries included are those for Atlantic cod, Gadus morhua; silver hake, Merluccius bilinearis;...
69.
Historical Exploitation of the California Sea Lion, Zalophus californianus, in México - Zavala-Gonzalez, Alfredo; Mellink, Eric
The exploitation of California sea lions, Zalophus californianus, in Mexican waters can be divided into four periods as defined by political characteristics of the country: Prehispanic, Colonial, Independent, and Postrevolutionary. During the first period (pre 1533), Native Americans took sea lions at low levels. During the second (1534–1821) and the third (1822–1911) periods, most exploitation was by foreigners and was incidental to other marine mammal harvests. During the Postrevolutionary period (after 1911), sea lions were exploited by Mexican and U.S. citizens for several commercial uses. Exploitation officially ended in 1982, although some small-scale poaching still occurs.
70.
Humpback and Fin Whaling in the Gulf of Maine from 1800 to 1918 - Reeves, Randall R.; Smith, Ted D.; Webb, Robert L.; Robbins, Jooke; Clapham, Phillip J.
The history of whaling in the Gulf of Maine was reviewed primarily to estimate removals of humpback whales, Megaptera novaeangliae, especially during the 19th century. In the decades from 1800 to 1860, whaling effort consisted of a few localized, small-scale, shore-based enterprises on the coast of Maine and Cape Cod, Mass. Provincetown and Nantucket schooners occasionally conducted short cruises for humpback whales in New England waters. With the development of bomb-lance technology at mid century, the ease of killing humpback whales and fin whales, Balaenoptera physalus, increased. As a result, by the 1870’s there was considerable local interest in hunting...
71.
Spatial and Temporal Distribution of Sea Turtles in the Western North Atlantic and the U.S. Gulf of Mexico from Marine Recreational Fishery Statistics Survey (MRFSS) - Braun-McNeill, Joanne; Epperly, Sheryan P.
Systematic surveys, along with opportunistic sightings, have provided important information on sea turtle (Cheloniidae and Dermochelydae) distributions, knowledge which can help reduce the risk of harmful human interaction. In 1991 and 1992, the Marine Recreational Fishery Sta-
tistics Survey (MRFSS) of the National Ma-
rine Fisheries Service, NOAA, provided a unique opportunity to gain additional, synoptic information on the spatial and temporal distribution of sea turtles along the U.S. Atlantic and Gulf of Mexico coasts by asking recreational anglers if they had observed a sea turtle on their fishing trip. During the spring and summer months of those years, as water temperatures...
72.
A Test of Computer-assisted Matching Using the North Pacific Humpback Whale, Megaptera novaeangliae, Tail Flukes Photograph Collection - Mizroch, Sally A.; Harkness, Suzanne A. D.
Testing was conducted of a computer-assisted system for matching humpback whale tail flukes photographs. Trials with a 12,000-photographs database found no differences in match success between matching by computer and matching by comparing smaller catalogs ranging in size from 200 to 400 photographs. Tests with a 24,000-photographs database showed that, on average, the first match was found after examining about 130 photographs whether the photograph quality was excellent, good, or poor. Match success did not appear to be strongly related to whether the tail flukes had especially distinctive markings or pigment patterns (recognition quality). An advantage of computer-assisted matching is...
73.
Estimates of Marine Mammal, Sea Turtle, and Seabird
Mortality in the California Drift Gillnet Fishery for
Swordfish and Thresher Shark, 1996–2002 - Caretta, James V.; Price, Tim; Petersen, Don; Read, Robert
Estimates of incidental marine mammal, sea turtle, and seabird mortality in the California drift gillnet fishery
for broadbill swordfish, Xiphias gladius, and common thresher shark, Alopias vulpinus, are summarized for the 7-year period, 1996 to 2002. Fishery observer coverage was 19% over the period (3,369 days observed/17,649 days fished). An experiment to test the effectiveness of acoustic
pingers on reducing marine mammal entanglements in this fishery began in 1996 and resulted in statistically significant reductions in marine mammal bycatch. The most commonly entangled marine mammal species were the short-beaked common dolphin, Delphinus delphis; California sea
lion, Zalophus californianus; and northern right whale dolphin,...
74.
Bottlenose Dolphins, Tursiops truncatus, Removing By-catch from Prawn-trawl Codends During Fishing in New South Wales, Australia - Broadhurst, M. K.
During a fishing trip to record video footage of fish escaping from a by-catch reducing device located in a commercial prawn trawl, two bottlenose dolphins, Tursiops truncatus, were observed to actively manipulate the codend at the seabed, removing and consuming components of catch (mostly juvenile whiting, Sillago spp.). The observed feeding pattern suggests a well established behavioral response to trawling activities and is discussed with
respect to (1) the potential nutritional benefit that dolphins may derive from such activities and (2) the effects that scavenging may have on selectivity of the gear.
75.
History of Whaling and Estimated Kill of Right Whales, Balaena glacialis, in the Northeastern United States, 1620–1924 - Reeves, Randall R.; Breiwick , Jeffrey M.; Mitchell , Edward D.
This study, part of a broader investigation of the history of exploitation of right whales, Balaena glacialis, in the western North Atlantic, emphasizes U.S. shore whaling from Maine to Delaware (from lat. 45°N to 38°30'N) in the period 1620–1924. Our broader study of the entire catch history
is intended to provide an empirical basis for assessing past distribution and abundance of this whale population.
Shore whaling may have begun at Cape Cod, Mass., in the 1620’s or 1630’s; it was certainly underway there by 1668. Right whale catches in New England waters peaked before 1725, and shore whaling at Cape Cod, Martha’s...
76.
Application of Marine Protected Areas for Sustainable Production and Marine Biodiversity off Alaska - Witherell, David; Woodby, Doug
Fisheries managers have established many marine protected areas (MPA’s) in the Federal and state waters off Alaska to protect ecological structure and function, establish control sites for scientific research studies, conserve benthic habitat, protect vulnerable stocks, and protect cultural resources. Many MPA’s achieve multiple objectives. Over 40 named MPA’s, many of which include several sites,
encompass virtually all Federal waters off Alaska and most of the state waters where commercial fisheries occur. All of
the MPA’s include measures to prohibit a particular fishery or gear type (particularly bottom trawls) on a seasonal or year-round basis, and several MPA’s prohibit virtually all commercial...
77.
Distribution and Abundance of Steller Sea Lions, Eumetopias jubatus, on the Asian Coast, 1720's-2005 - Burkanov, Vladimir N.; Loughlin, Thomas R.
We analyzed published and archived records for the past 250 years to assess changes in distribution and abundance of Steller sea lions, Eumetopias jubatus, along the Asian coast from the Bering Strait to the Korean Peninsula. We found that the northern extent of Steller sea lion
distribution has not changed but that the southern limit has moved north by some 500–900 km (~300–500 n.mi.) over the past 50 years. Additionally, the number of animals and their distribution has changed on the Commander Islands, Kuril Islands, and Kamchatka Peninsula. We found no changes
in the number of rookeries in the northern Sea of...
78.
The Geographic Distribution of Bowhead Whales, Balaena mysticetus, in the Bering, Chukchi, and Beaufort Seas: Evidence from Whaleship Records, 1849–1914 - Bockstoce, John R.; Botkin, Daniel B.; Philp, Alex; Collins, Brian W.; George, John C.
We have extracted, digitized, and analyzed information about
bowhead whales, Balaena mysticetus, contained in records of whaling cruises that were undertaken in the Bering, Chukchi,
and Beaufort Seas from 1849 to 1914. Our database consists of 65,000 days of observations which provide insights into whether this bowhead stock may comprise more than one population.
79.
Nesting Success of Kemp’s Ridley Sea Turtles, Lepidochelys kempi, at Rancho Nuevo, Tamaulipas, Mexico, 1982–2004 - Witzell, W. N.; Burchfield, P. M.; Pena, L. J.; Marquez-M. , R.; Ruiz-M., G.
The Kemp’s ridley sea turtle, Lepidochelys kempi, was on the edge of extinction owing to a combination of intense
egg harvesting and incidental capture in commercial fishing trawls. Results from a cooperative conservation strategy initiated in 1978 between Mexico and the United States to protect and restore the Kemp’s ridley turtle at the main nesting beach at Rancho Nuevo, Tamaulipas, Mexico are
assessed. This strategy appears to be working as there are signs that the species is starting to make a recovery. Recovery indicators include: 1) increased numbers of nesting turtles, 2) increased numbers of 100+ turtle nesting aggregations (arribadas), 3) an...
80.
A Whale of a Deception - Clapham, Phil; Ivashchenko, Yulia
In late October of 1966, an imposing ship steamed quietly through the placid waters of the Suez Canal. Clad in drab
industrial gray, and flying a Soviet hammer and sickle flag at her masthead, the vessel was accompanied by a large
fleet of smaller craft. Any observer able to decipher Cyrillic script could have read, in rusting metallic letters on her bow, the name Sovetskaya Ukraina. The more experienced would perhaps have identified her as a whaling factory ship, traveling with her attendant fleet of
catcher boats and scouting vessels on a transit that would take them south into the Red Sea and...
61.
