Group delay dispersion measurement of Yb : Gd2SiO5, Yb : GdYSiO5 and Yb : LuYSiO5 crystal with white-light interferometry

We report the measured group delay dispersion (GDD) of new crystals Yb:Gd2SiO5 (Yb:GSO), Yb:GdYSiO5 (Yb:GYSO) and Yb:LuYSiO5 (Yb:LYSO) over wavelengths from 1000nm to 1200nm, with a white-light interferometer. Those GDD data should be useful for the dispersion compensation for femtosecond pulse generation in the lasers with these new crystals as the gain media. (C) 2007 Optical Society of America

Food habits of Atlantic white-sided dolphins (Lagenorhynchus acutus) off the coast of New England

Although the Atlantic white-sided dolphin (Lagenorhynchus acutus) is one of the most common dolphins off New England, little has been documented about its diet in the western North Atlantic Ocean. Current federal protection of marine mammals limits the supply of animals for investigation to those incidentally caught in the nets of commercial fishermen with observers aboard. Stomachs of 62 L. acutus were examined; of these 62 individuals, 28 of them were caught by net and 34 were animals stranded on Cape Cod. Most of the net-caught L. acutus were from the deeper waters of the Gulf of Maine. A single stomach was from the continental slope south of Georges Bank. At least twenty-six fish species and three cephalopod species were eaten. The predominant prey were silver hake (Merluccius bilinearis), spoonarm octopus (Bathypolypus bairdii), and haddock (Melanogrammus aeglefinus). The stomach from a net-caught L. acutus on the continental slope contained 7750 otoliths of the Madeira lanternfish (Ceratoscopelus maderensis). Sand lances (Ammodytes spp.) were the most abundant (541 otoliths) species in the stomachs of stranded L. acutus. Seasonal variation in diet was indicated; pelagic Atlantic herring (Clupea harengus) was the most important prey in summer, but was rare in winter. The average length of fish prey was approximately 200 mm, and the average mantle length of cephalopod prey was approximately 50 mm.

Seasonal, diel, and lunar spawning periodicities and associated sound production of white seabass (Atractoscion nobilis)

Spawning periodicities of white seabass (Atractoscion nobilis) were evaluated by observing spawning behavior, by collecting eggs, and monitoring recognizable sounds produced during the release of gametes. A total of 297 spawning events were documented from 15 male and 47 female white seabass contained within the seminatural confines of a 526-m3 net pen located in Catalina Harbor, Santa Catalina Island, California. Consistent spawning occurred from March through July 2001−03, and peaked in May at a photoperiod of 14 hours. Most spawning occurred within the 2-hour period following sunset or from 19:00−20:00 hours Pacific Standard Time. White seabass spawned at every phase of the lunar cycle; but an increase in successive spawning events followed the new moon. Most spawning occurred in water temperatures from 15 to 18°C, and there was no apparent correlation with tidal cycles. Seasonal and diel spawning periods were directly correlated with increases in the rate, intensity, and variety of white seabass sounds; this correlation may indicate that sounds function to enhance reproductive success. These findings can be extended to further develop seasonal fishery regulations and to better comprehend the role of sound in the reproduction of sound-producing fishes.

The ecology of Atlantic white cedar wetlands: a community profile

This monograph on the ecology of Atlantic white cedar wetlands is one of a series of U.S. Fish and Wildlife Service profiles of important freshwater wetland ecosystems of the United States. The purpose of the profile is to describe the extent, components, functioning, history, and treatment of these wetlands. It is intended to provide a useful reference to relevant scientific information and a synthesis of the available literature. The world range of Atlantic white cedar (Chamaecyparis thyoides) is limited to a ribbon of freshwater wetlands within 200 km of the Atlantic and Gulf coasts of the United States, extending from mid-Maine to mid-Florida and Mississippi. Often in inaccessible sites and difficult to traverse, cedar wetlands contain distinctive suites of plant species. Highly valued as commercial timber since the early days of European colonization of the continent, the cedar and its habitat are rapidly disappearing. This profile describes the Atlantic white cedar and the bogs and swamps it dominates or codominates throughout its range, discussing interrelationships with other habitats, putative origins and migration patterns, substrate biogeochemistry, associated plant and animal species (with attention to those that are rare, endangered, or threatened regionally or nationally), and impacts of both natural and anthropogenic disturbance. Research needs for each area are outlined. Chapters are devoted to the practices and problems of harvest and management, and to an examination of a large preserve recently acquired by the USFWS, the Alligator River National Wildlife Refuge in North Carolina.

Removing observational noise from fisheries-independent time series data using ARIMA models

Abundance indices derived from fishery-independent surveys typically exhibit much higher interannual variability than is consistent with the within-survey variance or the life history of a species. This extra variability is essentially observation noise (i.e. measurement error); it probably reflects environmentally driven factors that affect catchability over time. Unfortunately, high observation noise reduces the ability to detect important changes in the underlying population abundance. In our study, a noise-reduction technique for uncorrelated observation noise that is based on autoregressive integrated moving average (ARIMA) time series modeling is investigated. The approach is applied to 18 time series of finfish abundance, which were derived from trawl survey data from the U.S. northeast continental shelf. Although the a priori assumption of a random-walk-plus-uncorrelated-noise model generally yielded a smoothed result that is pleasing to the eye, we recommend that the most appropriate ARIMA model be identified for the observed time series if the smoothed time series will be used for further analysis of the population dynamics of a species.

The use of multibeam sonar mapping techniques to refine population estimates of the endangered white abalone (Haliotis sorenseni)

Multibeam sonar mapping techniques provide detailed benthic habitat information that can be combined with the data on species-specific habitat preferences to provide highly accurate calculations of populations in a particular area. The amount of suitable habitat available for the endangered white abalone (Haliotis sorenseni) was quantified to aid in obtaining an accurate estimate of the number of remaining individuals at two offshore banks and one island site off the coast of southern California. Habitat was mapped by using multibeam sonar survey techniques and categorized by using rugosity and topographic position analysis. Abalone densities were evaluated by using a remotely operated vehicle and video transect methods. The total amount of suitable habitat at these three sites was far greater than that previously estimated. Therefore, although present estimates of white abalone densities are several orders of magnitude lower than historic estimates, the total population is likely larger than previously reported because of the additional amount of habitat surveyed in this study.

Survival of white marlin (Tetrapturus albidus) released from commercial pelagic longline gear in the western North Atlantic

To estimate postrelease survival of white marlin (Tetrapturus albidus) caught incidentally in regular commercial pelagic longline fishing operations targeting swordfish and tunas, short-duration popup satellite archival tags (PSATs) were deployed on captured animals for periods of 5−43 days. Twenty (71.4%) of 28 tags transmitted data at the preprogrammed time, including one tag that separated from the fish shortly after release and was omitted from subsequent analyses. Transmitted data from 17 of 19 tags were consistent with survival of those animals for the duration of the tag deployment. Postrelease survival estimates ranged from 63.0% (assuming all nontransmitting tags were evidence of mortality) to 89.5% (excluding nontransmitting tags from the analysis). These results indicate that white marlin can survive the trauma resulting from interaction with pelagic longline gear, and indicate that current domestic and international management measures requiring the release of live white marlin from this fishery will reduce fishing mortality on the Atlantic-wide stock.