Interpreting spotted dolphin age distributions

Previous work has determined the age distribution from a sample of spotted dolphins (Stenella attenuata) killed in the eastern Pacific tuna purse-seine fishery. In this paper we examine the usefulness of this age distribution for estimating natural mortality rates. The observed age distribution has a deficiency of individuals from 5-15 years and cannot represent a stable age distribution. Sampling bias and errors in age interpretation are examined as possible causes of the "dip" in the observed age structure. Natural mortality rates are estimated for the 15+ age classes based on the assumption that these are sampled representatively. The resulting annual survival rate <D.82) is too low to allow population growth, given what is known about dolphin reproductive rates. (PDF contains 30 pages.

Engineering system modeling for sustainability assessment

2016 Fall.Includes bibliographical references.The increase in global greenhouse gas emissions has driven interest in the development of renewable energy sources. The commercial development of emerging renewable technologies like algal biofuels requires the identification of an economically viable production pathway. This study examined the sustainability of generating renewable diesel via hydrothermal liquefaction (HTL) of algal biomass from an attached growth architecture. Pilot-scale growth studies and laboratory-scale HTL experiments validated an engineering system model, which facilitated analysis of economic feasibility and environmental impact of the system at full scale. Techno-economic analysis (TEA) results indicate an optimized minimum fuel selling price (MFSP) of $11.90 gal-1, and life-cycle assessment (LCA) found a global warming potential (GWP) of -44 g CO2-e MJ-1 and net energy ratio of 0.33. Results from this work identified current gaps in sustainability assessment through TEA and LCA. Two needs were identified to improve sustainability assessment: the internalization of a carbon emission price into TEA and the consideration of the time-value of carbon emissions in LCA. With these effects considered, MFSP and GWP increase by 23% for the modeled biofuels system. Results from a harmonized model of an array of energy technologies indicate that prices for fossil-based energy increase 200% and GWP increases 25% when these factors are considered, whereas low-emitting technologies increase minimally in both metrics. Based on these findings, the development of improved sustainability assessment methodology is proposed

A New Birth-Interval Approach to Estimating Demographic Parameters of Humpback Whales

A demographic model is developed based on interbirth intervals and is applied to estimate the population growth rate of humpback whales (Megaptera novaeangliae) in the Gulf of Maine. Fecundity rates in this model are based on the probabilities of giving birth at time t after a previous birth and on the probabilities of giving birth first at age x. Maximum likelihood methods are used to estimate these probabilities using sighting data collected for individually identified whales. Female survival rates are estimated from these same sighting data using a modified Jolly–Seber method. The youngest age at first parturition is 5 yr, the estimated mean birth interval is 2.38 yr (SE = 0.10 yr), the estimated noncalf survival rate is 0.960 (SE = 0.008), and the estimated calf survival rate is 0.875 (SE = 0.047). The population growth rate (l) is estimated to be 1.065; its standard error is estimated as 0.012 using a Monte Carlo approach, which simulated sampling from a hypothetical population of whales. The simulation is also used to investigate the bias in estimating birth intervals by previous methods. The approach developed here is applicable to studies of other populations for which individual interbirth intervals can be measured

A New Birth-Interval Approach to Estimating Demographic Parameters of Humpback Whales

A demographic model is developed based on interbirth intervals and is applied to estimate the population growth rate of humpback whales (Megaptera novaeangliae) in the Gulf of Maine. Fecundity rates in this model are based on the probabilities of giving birth at time t after a previous birth and on the probabilities of giving birth first at age x. Maximum likelihood methods are used to estimate these probabilities using sighting data collected for individually identified whales. Female survival rates are estimated from these same sighting data using a modified Jolly–Seber method. The youngest age at first parturition is 5 yr, the estimated mean birth interval is 2.38 yr (SE = 0.10 yr), the estimated noncalf survival rate is 0.960 (SE = 0.008), and the estimated calf survival rate is 0.875 (SE = 0.047). The population growth rate (l) is estimated to be 1.065; its standard error is estimated as 0.012 using a Monte Carlo approach, which simulated sampling from a hypothetical population of whales. The simulation is also used to investigate the bias in estimating birth intervals by previous methods. The approach developed here is applicable to studies of other populations for which individual interbirth intervals can be measured

A New Birth-Interval Approach to Estimating Demographic Parameters of Humpback Whales

A demographic model is developed based on interbirth intervals and is applied to estimate the population growth rate of humpback whales (Megaptera novaeangliae) in the Gulf of Maine. Fecundity rates in this model are based on the probabilities of giving birth at time t after a previous birth and on the probabilities of giving birth first at age x. Maximum likelihood methods are used to estimate these probabilities using sighting data collected for individually identified whales. Female survival rates are estimated from these same sighting data using a modified Jolly–Seber method. The youngest age at first parturition is 5 yr, the estimated mean birth interval is 2.38 yr (SE = 0.10 yr), the estimated noncalf survival rate is 0.960 (SE = 0.008), and the estimated calf survival rate is 0.875 (SE = 0.047). The population growth rate (l) is estimated to be 1.065; its standard error is estimated as 0.012 using a Monte Carlo approach, which simulated sampling from a hypothetical population of whales. The simulation is also used to investigate the bias in estimating birth intervals by previous methods. The approach developed here is applicable to studies of other populations for which individual interbirth intervals can be measured

SOUNDS RECORDED FROM BAIRD\u27S BEAKED WHALE, \u3ci\u3eBERARDIUS BAIRDII\u3c/i\u3e

The vocal behavior of ziphiid whales is very poorly known. Free-swimming northern bottlenose whales, Hyperoodon ampullatus, have been recorded producing 3-16 kHz whistles and chirps (Winn et al. 1970; linear equipment frequency response 500 Hz-14 kHz) and 20-30 kHz ultrasonic clicks (Fauchner and Whitehead, unpublished data; equipment response to 35 kHz). A free-swimming mesoplodont beaked whale (probably Mesoplodon hertori) produced ultrasonic clicks (Ljungblad, unpublished data; equipment frequency response to 32 kHz). Sounds have been recorded from a stranded Blainville\u27s beaked whale, Mesoplodon densirostris (Caldwell and Caldwell 1971; equipment frequency response 40 Hz-20 kHz) and a post-stranding, captive Hubb\u27s beaked whale, Mesoplodon carlhubbsi (Lynn and Reiss 1992; equipment frequency response 70 Hz-40 kHz). The latter two species produced low-frequency pulses (mostly \u3c 2 kHz). The Hubb\u27s beaked whale also produced broadband clicks extending beyond the limit of the recording gear (\u3e 40 kHz) and a few weak whistles (\u3c 10.7 kHz). During cetacean survey cruises conducted by the National Marine Fisheries Service off the coasts of Oregon, U.S.A., and Baja California, Mexico, we recently made what we believe to be the first recordings of Baird\u27s beaked whales (Berardius bairdii). On 27 July 1994 the NOAA Ship Snrveyor encountered a group of 30-35 Baird\u27s beaked whales about 225 nmi west of Hecata Head, Oregon (at 44°10\u27N, 129°10\u27W). Two sonobuoys (ex U.S. Navy, type 57B) were deployed. The first was deployed 1.6 nmi away from the animals, before a rigid-hulled inflatable boat (RHIB) was launched. The second was deployed 55 min later from the RHIB, within tens of meters from the animals. To relocate the animals after each dive, a continuous search was maintained by two observers searching the forward quadrants with 25X binoculars and two or more additional observers searching all quadrants with 7X binoculars and unaided eyes. The only other cetacean seen during this time was one large sperm whale 6-10 nmi away. Sounds were recorded using a Nagra IV-SJ analog tape recorder, for a total system response from 20 Hz to 20 kHz. We filtered these recordings at 20 kHz (low pass) and digitized them at 44.1 kHz (16 bit). Spectrograms (4096 pt FFT, 1024 pt frame length, 87.5% overlap, 174.85 Hz analyzing filter bandwidth) were generated using Canary™ signal processing software (v. 1.2.1; Cornell University), running on a Power Macintosh™ 760011 20

BLUE WHALE VISUAL AND ACOUSTIC ENCOUNTER RATES IN THE SOUTHERN CALIFORNIA BIGHT

The relationship between blue whale (Balaenoptera musculus) visual and acoustic encounter rates was quantitatively evaluated using hourly counts of detected whales during shipboard surveys off southern California. Encounter rates were estimated using temporal, geographic, and weather variables within a generalized additive model framework. Visual encounters (2.06 animals/h, CV = 0.10) varied with subregion, Julian day, time of day, and year. Acoustic encounters of whales producing pulsed A and tonal B call sequences (song; 0.65 animals/h, CV = 0.06) varied by Julian day, survey mode (transit or stationary), and subregion, and encounters of whales producing downswept (D) calls (0.41 animals/h, CV=0.09) varied by Julian day and the number of animals seen. Inclusion of Julian day in all models reflects the seasonal occurrence of blue whales off southern California; however, the seasonal peak in visual encounters and acoustic encounters of D calling whales (July–August) was offset from the peak in acoustic encounters of singing whales (August–September). The relationship between visual and acoustic encounter rates varied regionally, with significant differences in several northern regions. The number of whales heard D calling was positively related to the number of animals seen, whereas the number of singing whales was not related to visual encounter rate

Abundance and population density of cetaceans in the California Current ecosystem

The abundance and population density of cetaceans along the U.S. west coast were estimated from ship surveys conducted in the summer and fall of 1991, 1993, 1996, 2001, and 2005 by using multiple-covariate, line-transect analyses. Overall, approximately 556,000 cetaceans of 21 species were estimated to be in the 1,141,800-km2 study area. Delphinoids (Delphinidae and Phocoenidae), the most abundant group, numbered ~540,000 individuals. Abundance in other taxonomic groups included ~5800 baleen whales (Mysticeti), ~7000 beaked whales (Ziphiidae), and ~3200 sperm whales (Physeteridae). This study provides the longest time series of abundance estimates that includes all the cetacean species in any marine ecosystem. These estimates will be used to interpret the impacts of human-caused mortality (such as that documented in fishery bycatch and that caused by ship strikes and other means) and to evaluate the ecological role of cetaceans in the California Current ecosystem

Acoustic differentiation of Shiho- and Naisa-type short-finned pilot whales in the Pacific Ocean

Author Posting. © Acoustical Society of America, 2017. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 114 (2017): 737–748, doi: 10.1121/1.4974858.Divergence in acoustic signals used by different populations of marine mammals can be caused by a variety of environmental, hereditary, or social factors, and can indicate isolation between those populations. Two types of genetically and morphologically distinct short-finned pilot whales, called the Naisa- and Shiho-types when first described off Japan, have been identified in the Pacific Ocean. Acoustic differentiation between these types would support their designation as sub-species or species, and improve the understanding of their distribution in areas where genetic samples are difficult to obtain. Calls from two regions representing the two types were analyzed using 24 recordings from Hawai‘i (Naisa-type) and 12 recordings from the eastern Pacific Ocean (Shiho-type). Calls from the two types were significantly differentiated in median start frequency, frequency range, and duration, and were significantly differentiated in the cumulative distribution of start frequency, frequency range, and duration. Gaussian mixture models were used to classify calls from the two different regions with 74% accuracy, which was significantly greater than chance. The results of these analyses indicate that the two types are acoustically distinct, which supports the hypothesis that the two types may be separate sub-species.Funding for Hawaiian data collection was provided by grants from the Pacific Islands Fisheries Science Center and Office of Naval Research, as well as Commander, Pacific Fleet. The SoundTrap was purchased with funding from the Scripps Institution of Oceanography/National Science Foundation Interdisciplinary Graduate Education in Research Techniques fellowship program. DMON data collection and portions of the analysis were funded by the Office of Naval Research [Grant Nos. N000141110612 (T.A.M. and R.W.B.) and N00014-15-1-2299 (M.A.R.); Program Manager Michael J. Weise], and WHOI Marine Mammal Center and the Sawyer and Penzance Endowed Funds to T.A.M