bluuebunny/crossref_metadata_2025_split huggingface dataset:
FIELD EXPERIMENTS SHOW THAT ACOUSTIC PINGERS REDUCE MARINE MAMMAL BYCATCH IN THE CALIFORNIA DRIFT GILL NET FISHERY
Authors: Barlow Jay , Cameron Grant A. 
Published: August 2006

AbstractA controlled experiment was carried out in 1996–1997 to determine whether acoustic deterrent devices (pingers) reduce marine mammal bycatch in the California drift gill net fishery for swordfish and sharks. Using Fisher's exact test, bycatch rates with pingers were significantly less for all cetacean species combined (P< 0.001) and for all pinniped species combined (P= 0.003). For species tested separately with this test, bycatch reduction was statistically significant for short‐beaked common dolphins (P= 0.001) and California sea lions (P= 0.02). Bycatch reduction is not statistically significant for the other species tested separately, but sample sizes and statistical power were low, and bycatch rates were lower in pingered nets for six of the eight other cetacean and pinniped species. A log‐linear model relating the mean rate of entanglement to the number of pingers deployed was fit to the data for three groups: short‐beaked common dolphins, other cetaceans, and pinnipeds. For a net with 40 pingers, the models predict approximately a 12‐fold decrease in entanglement for short‐beaked common dolphins, a 4‐fold decrease for other cetaceans, and a 3‐fold decrease for pinnipeds. No other variables were found that could explain this effect. The pinger experiment ended when regulations were enacted to make pingers mandatory in this fishery.
CONSEQUENCES OF ALTERNATIVE FUNCTIONAL RESPONSE FORMULATIONS IN MODELS EXPLORING WHALE‐FISHERY INTERACTIONS
Authors: Mackinson Steven , Blanchard Julia L. , Pinnegar John K. , Scott Robert 
Published: August 2006

AbstractWe evaluated the utility of Ecosim for exploring interactions between cetacean predators, their prey, and fisheries. We formulated six Ecosim parameterizations, representing alternative hypotheses of feeding interactions (functional response) between cetaceans and their main fish prey, and examined differences in the predicted responses to simulated harvesting regimes for minke whales and their prey. Regardless of the type of function response formulated, intense fishing on the main fish prey of minke whales had a longer‐lasting negative impact on minke whales than when minke whale biomass was removed directly by harvesting. Consumption rate, biomass, feeding time and mortality of minke whales were all sensitive to the type of functional response specified. Inclusion of “handling time” limited minke whales consumption at high prey densities and predicted higher consumption at low prey densities; features characteristic of a type II functional response. Predicted decline and recovery rates of minke whales were slower than when consumption rates were not limited. Addition of “foraging time” adjustments resulted in more conservative estimates of decline and recovery. However, when “other mortality” was linked to time spent foraging, exposure to higher mortality at low prey densities, and reduced mortality at high prey densities resulted in dramatic differences in predicted biomass trajectory. Sensitivity to the “other mortality” assumption is important for cetaceans whose predation mortality is only a small proportion of total mortality. Differences in the feeding and biomass dynamics were also observed when prey availability to predators was represented by changes in prey vulnerability, confirming earlier reports that Ecosim predictions are sensitive to this parameter.
SEASONAL DISTRIBUTION OF STELLER'S SEA LIONS AT ROOKERIES AND HAUL‐OUT SITES IN ALASKA
Authors: Sease John L. , York Anne E. 
Published: August 2006

AbstractThe Steller's sea lion population has declined by 60%‐70% over much of Alaska since the late 1970s. Overlap in species composition and sizes of fishes consumed by sea lions and harvested by commercial fisheries, particularly during winter, has led to examination of potential interaction between commercial fisheries and Steller's sea lions. Abundance and distribution data for Steller's sea lions in Alaska were derived from aerial surveys conducted during the breeding season, mid‐June to early July 1992, 1994, and 1996. To study winter distribution of sea lions, we conducted aerial surveys during March 1993, November‐December 1994, and March 1999. We counted about one‐half as many sea lions during winter surveys compared to the breeding‐season surveys. Numbers of sea lions at rookery sites dropped off considerably during winter, whereas numbers at haul‐out sites did not. We found little evidence of large‐scale, seasonal movement, at least for the western stock of sea lions. Rather, differences between summer and winter distribution were primarily a function of sea lions dispersing to local haul‐out sites during the winter. Terrestrial sites, both rookeries and haul‐outs, clearly are important to Steller's sea lions during the entire year. Individual sites may be occupied year‐round or only during particular times of year.
APPEARANCE, DISTRIBUTION, AND GENETIC DISTINCTIVENESS OF LONGMAN'S BEAKED WHALE, INDOPACETUS PACIFICUS
Authors: Dalebout Merel L. , Baker C. Scott , Anderson R. Charles , Best Peter B. , Cockcroft Victor G. , Hinsz Harvey L. , Peddemors Victor , Pitman Robert L. 
Published: August 2006

AbstractLongman's beaked whale, Indopacetus pacificus, was known previously from only two skulls. Here we describe four new specimens of this species from strandings in the western and central Indian Ocean. Two juveniles, previously misidentified from external morphology as Hyperoodon planifrons, were identified as I. pacificus through diagnostic characteristics of mitochondrial (mt) DNA sequences derived from the holotype of this species. Images of the external appearance and teeth of the species are presented for the first time. Comparison of the color pattern of these new specimens with that of “tropical bottlenose whales” sighted in the tropical Indian and Pacific oceans confirm that those unidentified whales represent I. pacificus. Moore (1968) erected a new genus, Indopacetus, for this species (described initially as Mesoplodon pacificus) based primarily on cranial morphology. Phylogenetic analyses of short mtDNA fragments available from the specimens known to date were unable to resolve the validity of this genus. However, the diagnostic osteological features highlighted by Moore (1968) for Indopacetus were also observed in the new specimens. Rib count and number of fused cervical vertebrae may also be diagnostic. Rostrum depth at mid‐length and melon shape further distinguish this species from Mesoplodon beaked whales. As such, we see no reason on morphological grounds to overturn Moore's (1968) proposal that Longman's beaked whale is sufficiently distinct to be afforded its own genus.
SEXUAL ECOLOGY OF THE SPINNER DOLPHIN, STENELLA LONGIROSTRIS: GEOGRAPHIC VARIATION IN MATING SYSTEM
Authors: Perrin William F. , Mesnick Sarah L. 
Published: August 2006

AbstractWe offer the first report for a cetacean of geographical variation in mating system based in morphology. Analysis of samples from 1,678 male spinner dolphins from the eastern Pacific revealed that testis + epididymis weight was greater (to 1,354 g) in the whitebelly form of the species than in the eastern form (to 843 g). Sexual dimorphism in dorsal‐fin shape is greater in the eastern form. The difference in testis size was strongly linked with shape of the dorsal fin on an individual basis. Only a few eastern males (0.6%) reached testis + epididymis weight at which all epididymides contain sperm, while a much larger proportion of whitebelly spinners (15.2%) reached this level, suggesting that a smaller proportion of eastern spinner males may participate in reproductive activity. This, and the fact that increased dimorphism and decreased testis size are indicative of increased polygyny in a wide variety of other mammal species, leads to the conclusion that the mating system varies geographically in the species, with a gradient from a more polygynous mating system in the eastern form to a more open or polygynandrous mating system in the whitebelly form. Differences in ovulation rate in the two forms are consistent with this conclusion.
STABILIZATION MECHANISM IN SWIMMING ODONTOCETE CETACEANS BY PHASED MOVEMENTS
Authors: Fish F. E. , Peacock J. E. , Rohr J. J. 
Published: August 2006

AbstractPropulsive movements of the caudal oscillating flukes produce large forces that could induce equally large recoil forces at the cranial end of the animal, and, thus, affect stability. To examine these vertical oscillations, video analysis was used to measure the motions of the rostrum, pectoral flipper, caudal peduncle, and fluke tip for seven odontocete cetaceans: Delphinapterus leucas, Globicephala melaena, Lagenorhynchus obliquidens, Orcinus orca, Pseudorca crassidens, Stenella plagiodon, and Tursiops truncatus. Animals swam over a range of speeds of 1.4–7.30 m/sec. For each species, oscillatory frequency of the fluke tip increased linearly with swimming speed. Peak‐to‐peak amplitude at each body position remained constant with respect to swimming speed for all species. Mean peak‐to‐peak amplitude ranged from 0.02 to 0.06 body length at the rostrum and from 0.17 to 0.25 body length at the fluke tip. The phase relationships between the various body components remain constant with respect to swimming speed. Oscillations of the rostrum were nearly in phase with the fluke tip with phase differences out of—9.4°‐33.0° of a cycle period of 360°. Pectoral flipper oscillations trailed fluke oscillations by 60.9°‐123.4°. The lower range in amplitude at the rostrum compared to the fluke tip reflects increased resistance to vertical oscillation at the cranial end, which enhances the animal's stability. This resistance is likely due to both active and passive increased body stiffness, resistance on the flippers, phased movements of body components, and use of a lift‐based propulsion. Collectively, these mechanisms stabilize the body of cetaceans during active swimming, which can reduce locomotor energy expenditure and reduce excessive motions of the head affecting sensory capabilities.
KILLER WHALE PREDATION ON BELUGAS IN COOK INLET, ALASKA: IMPLICATIONS FOR A DEPLETED POPULATION
Authors: Shelden Kim E. W. , Rugh David J. , Mahoney BarbaraA. , Dahlheim Marilyn E. 
Published: August 2006

AbstractKiller whale predation on belugas in Cook Inlet, Alaska, has become a concern since the decline of these belugas was documented during the 1990s. Accordingly, killer whale sightings were compiled from systematic surveys, observer databases, and anecdotal accounts. Killer whales have been relatively common in lower Cook Inlet (at least 100 sightings from 1975 to 2002), but in the upper Inlet, north of Kalgin Island, sightings were infrequent (18 in 27 yr), especially prior to the 1990s. Beach cast beluga carcasses with teeth marks and missing flesh also provided evidence of killer whale predation. Most observed killer whale/beluga interactions were in the upper Inlet. During 11 of 15 observed interactions, belugas were obviously injured or killed, either through direct attacks or indirectly as a result of stranding. Assuming at least one beluga mortality occurred during the other four encounters, we can account for 21 belugas killed between 1985 and 2002. This would suggest a minimum estimate of roughly 1/yr and does not include at least three instances where beluga calves accompanied an adult that was attacked.
PINNIPED LACTATION STRATEGIES: EVALUATION OF DATA ON MATERNAL AND OFFSPRING LIFE HISTORY TRAITS
Authors: Schulz Tyler M. , Bowen W. Don 
Published: August 2006

AbstractInterspecific correlations are commonly used to explore the adaptive functions of life history traits in pinnipeds. Although adaptive conclusions are improved by the use of comparative methods that account for underlying phylogenetic relationships among species, they are still dependent on the quality of life history data. We collected pinniped species estimates for 12 maternal and offspring life history traits and evaluated these estimates based on sample size, duration of study, and methods used to obtain the data. Although excellent data exist for some species, high‐quality estimates in all 33 species are not available for any of the traits studied. High‐quality estimates of maternal postpartum mass are known for 12 species, neonate birth mass for 21, pup rate of mass gain for 12, lactation length for 10, and weaning mass for 10. High‐quality estimates of milk composition, milk energy output, and maternal foraging behavior during lactation are limited to ≤ 50% of species, with a taxonomic bias favoring the larger phocid species. Obtaining data on small‐bodied phocid species will be critical to gaining a better understanding of the relative roles of body size and phylogeny in the evolution of pinniped lactation strategies.
FEEDING ECOLOGY OF THE MARINE OTTER (LUTRA FELINA) IN A ROCKY SEASHORE OF THE SOUTH OF CHILE
Authors: Medina‐Vogel Gonzalo , Rodriguez Claudio Delgado , Ricardo E. Alvarez P. , Jose Luis Bartheld V. 
Published: August 2006

AbstractThe marine otter (Lutra felina) lives exclusively along exposed rocky shorelines on the South American Pacific coast from Peru (6°S), to Cape Horn, Chile (56°S), and Isla de los Estados, Argentina. L. felina diet and its relationship to prey availability and energy content was assessed by spraint and prey remains analysis, direct observation, and the use of crab pots and fish traps, at four sites on the Valdivian coast in the south of Chile, between June 1999 and June 2000. Based on spraints analysis, the diet was composed of 25 species; 52% (13/25) of the species identified were crustaceans, 40% (10/25) were fish, and 8% (2/25) were mollusks. Crustaceans were found in 78% of 475 spraints, 100% of 929 prey remains, and 90.8% of prey determined by direct observation, fish in 20% of spraints and 9.0% of prey determined by direct observation, and mollusks in 2% of spraints and 0.2% of prey determined by direct observation. Observed seasonal variation in prey availability was reflected in the otter diet. Fourteen prey species were trapped; 43% (6/14) were crustaceans and 57% (8/14) fish, crustaceans were 93% of 566 trapped individuals, fish 7%. L. felina showed opportunistic feeding behavior, selecting prey seasonally according to their availability rather than to their energy input.
RIVERINE HABITAT PREFERENCES OF BOTOS (INIA GEOFFRENSIS) AND TUCUXIS (SOTALIA FLUVIATILIS) IN THE CENTRAL AMAZON
Authors: Martin A. R. , da Silva V. M. F. , Salmon D. L. 
Published: August 2006

AbstractThe distribution and density of the Amazon's two contrasting endemic dolphins–boto, or Amazon river dolphin, Inia geoffrensis, and tucuxi, Sotalia fluviatilis–were examined on two adjoining large rivers in western Brazil. Using a 17‐m river boat as a sightings platform, strip transects were used to cover areas within 150 m of the river margin and line transects were used in all other areas. Highest densities of both dolphins occurred near the margin, and lowest in the center of rivers. Seven different habitats were identified along river margins. The boto and the tucuxi differed in some elements of habitat choice, but they shared a preference for areas with diminished current and where two channels joined. Neither species favored the two most common edge types in this region of the Amazon‐mud banks and flooded forest margins. Overall, the most preferred habitat type was the least common, and known as “meeting of the waters.” In these areas a channel of sediment‐rich white water meets one carrying acidic black water; the resultant mixing produces particularly productive, and obviously attractive, conditions for dolphins. These results demonstrate that Amazonian dolphins selectively occur in areas known to be favored for gill net deployment by local fishermen, and may explain why entanglement is apparently a common cause of mortality.
DUSKY DOLPHIN (LAGENORHYNCHUS OBSCURUS) FORAGING IN TWO DIFFERENT HABITATS: ACTIVE ACOUSTIC DETECTION OF DOLPHINS AND THEIR PREY
Authors: Benoit‐Bird Kelly J. , Würsig Bernd , Mfadden Cynthia J. 
Published: August 2006

AbstractActive‐acoustic surveys were used to determine the distribution of dusky dolphins and potential prey in two different New Zealand locations. During seven survey days off Kaikoura Canyon, dusky dolphins were found within the DeepScattering Layer (DSL) at 2000 when it rose to within 125 m of the surface. As the DSL rose to 30 m at 0100, the observed depth of dolphins decreased, presumably as the dolphins followed the vertical migration of their prey. Acoustically identified subgroups of coordinated animals ranged from one to five dolphins. Time, depth of layer, and layer variance contributed significantly to predicting foraging dusky dolphin subgroup size. In the much shallower and more enclosed Admiralty Bay, dolphins noted at the surface as foraging were always detected with the sonar, but were never observed in coordinated subgroups during the brief (two‐day) study there. In Admiralty Bay dolphin abundance was correlated with mean volume scattering from potential prey in the water column; and when volume scattering, an index of prey density, was low, dolphins were rarely present. Ecological differences between the deep waters of Kaikoura Canyon and the shallow nearshore waters of Admiralty Bay may result in differences in how, when, and in what social groupings dusky dolphins forage.
PHONING HOME‐A NEW GSM MOBILE PHONE TELEMETRY SYSTEM TO COLLECT MARK‐RECAPTURE DATA
Authors: Mcconnell Bernie , Beaton Rory , Bryant Ed , Hunter Colin , Lovell Phil , Hall Ailsa 
Published: August 2006

AbstractWe describe and evaluate a new telemetry system based on GSM (Global System for Mobile Communications) mobile phone technology that may provide mark‐recapture data for single year survivorship studies. These phone‐tags automatically attempt to send an SMS text message once every two days. The successful receipt of a text message ashore constitutes a resighting event within the coastal zone of GSM coverage. Haul‐out data and coastal location data are incorporated into the messages. Data are presented for a three‐month period (January‐March) following tag deployment on 59 gray seal (Halichoerus grypus) pups at the Isle of May (Scotland). An average of 15.5, 4.1, and 8.2 seals succeeded in registering within each three‐day period in January, February, and March, respectively. Tags registered with a wide geographical range of GSM radio cells on the Scottish and English east coasts, and also from Norway and Germany. Haulout records covering 54% of the animals' time were received. With future modifications to the tags, this figure should approach 100%. The median delay to network registration was 9.6 sec from a seal in the sea (not hauled out). These data show that GSM mobile phone telemetry is a useful technique to obtain haul‐out and mark‐recapture data.
GROWTH RATE AND SHEDDING OF VIBRISSAE IN THE GRAY SEAL, HALICHOERUS GRYPUS: A CAUTIONARY NOTE FOR STABLE ISOTOPE DIET ANALYSIS
Authors: Greaves Danielle K. , Hammill Michael O. , Eddington Jim D. , Pettipas Darcy , Schreer Jason F. 
Published: August 2006

AbstractStable isotopes have become powerful tools for gathering information on food webs in marine ecosystems. The method is based on the concept that the ratio of Nitrogen‐14 to 15N (or Carbon‐12 to 13C) in the tissues of animals is directly related to the ratio found in their diet. Vibrissae provide a time series of stable isotope data as tissue is laid down sequentially over time. Here we examine the growth rate of 283 mystacial (muzzle) vibrissae of four gray seals, Halichoeruas grypus, over a five‐month period to investigate their applicability for stable isotope diet analysis. The individual vibrissae did not grow at a constant rate during the study, Fifty‐nine actively growing vibrissae were modeled to quantify the growth pattern using a three‐parameter von Bertalanffy curve, with the parameters estimated using non‐linear mixed‐effects models. This model incorporated the inherent serial correlation of these data. The growth rate was 0.024 cm/d (95% CI = 0.019–0.030), the asymptotic length differed significantly by location (F3,56=9.64, P < 0.001), but no significant trend was found with muzzle location (F3,56= 0.15, P= 0.93). The Δlength/Δtime between each measurement was calculated and most of these data fell at or near zero growth (median = 0.04 cm/d, range = 0–0.78). Individual vibrissae were shed asynchronously and without any seasonal growth trend. This has serious implications for researchers attempting to extrapolate diet data from vibrissae. Because the growth is neither continuous nor synchronous, it will be a challenge to accurately identify the dates when the isotopes were incorporated into the tissue.
CAPTURE‐RECAPTURE ANALYSIS FOR ESTIMATING MANATEE REPRODUCTIVE RATES
Authors: Kendall William L. , Langtimm Catherine A. , Beck Cathy A. , Runge Michael C. 
Published: August 2006

AbstractModeling the life history of the endangered Florida manatee (Trichechus manatus latirostris) is an important step toward understanding its population dynamics and predicting its response to management actions. We developed a multi‐state markresighting model for data collected under Pollock's robust design. This model estimates breeding probability conditional on a female's breeding state in the previous year; assumes sighting probability depends on breeding state; and corrects for misclassification of a cow with first‐year calf, by estimating conditional sighting probability for the calf. The model is also appropriate for estimating survival and unconditional breeding probabilities when the study area is closed to temporary emigration across years. We applied this model to photo‐identification data for the Northwest and Atlantic Coast populations of manatees, for years 1982–2000. With rare exceptions, manatees do not reproduce in two consecutive years. For those without a first‐year calf in the previous year, the best‐fitting model included constant probabilities of producing a calf for the Northwest (0.43, SE = 0.057) and Atlantic (0.38, SE = 0.045) populations. The approach we present to adjust for misclassification of breeding state could be applicable to a large number of marine mammal populations.
SURVIVAL ESTIMATES FOR FLORIDA MANATEES FROM THE PHOTO‐IDENTIFICATION OF INDIVIDUALS
Authors: Langtimm Catherine A. , Beck Cathy A. , Edwards Holly H. , Fick‐Child Kristin J. , Ackerman Bruce B. , Barton Sheri L. , Hartley Wayne C. 
Published: August 2006

AbstractWe estimated adult survival probabilities for the endangered Florida manatee (Trichechus manatus latirostris) in four regional populations using photoidentification data and open‐population capture‐recapture statistical models. The mean annual adult survival probability over the most recent 10‐yr period of available estimates was as follows: Northwest ‐ 0.956 (SE 0.007), Upper St. Johns River ‐ 0.960 (0.011), Atlantic Coast ‐ 0.937 (0.008), and Southwest ‐ 0.908 (0.019). Estimates of temporal variance independent of sampling error, calculated from the survival estimates, indicated constant survival in the Upper St. Johns River, true temporal variability in the Northwest and Atlantic Coast, and large sampling variability obscuring estimates for the Southwest. Calf and subadult survival probabilities were estimated for the Upper St. Johns River from the only available data for known‐aged individuals: 0.810 (95% CI 0.727–0.873) for 1st year calves, 0.915 (0.827–0.960) for 2nd year calves, and 0.969 (0.946–0.982) for manatee 3 yr or older. These estimates of survival probabilities and temporal variance, in conjunction with estimates of reproduction probabilities from photoidentification data can be used to model manatee population dynamics, estimate population growth rates, and provide an integrated measure of regional status.