Hiscock K.,Marine Biological Association of The United Kingdom |
Bayley D.,Marine Biological Association of The United Kingdom |
Pade N.,Marine Biological Association of The United Kingdom |
Lacey C.,SMRU Ltd |
And 2 more authors.
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2013
A method is described and tested for identifying and prioritizing actions to facilitate recovery (restoration) and/or conservation (maintenance) of populations of threatened marine species. The exercise was based on established approaches for terrestrial species and on assessing each species according to 'degree of threat' and 'recovery/conservation potential'. Assessment of both degree of threat and recovery/conservation potential was informed by researching the relevant life-history traits of each species and existing knowledge of natural fluctuations in abundance. 'Rarity' was a key consideration in assessing degree of threat but rarity measures for cetaceans and pelagic fishes were not available and a new methodology was therefore developed. Likely actions for maintenance or recovery of a population of a species were specified under the headings: 'Site Management', 'Translocation', 'Enforcement', 'Research', 'Monitoring' and 'Wider Environment'. The recovery/conservation goal for each species was identified according to SMART (Specific, Measurable, Attainable, Relevant and Time-bound) criteria. The terrestrial approach transferred well to marine species but with some adaptation as the marine environment is different to terrestrial ecosystems in the pressures and activities that are likely to adversely affect species, to our knowledge of decline in species and to the ecological processes that are likely to aid recovery. The species researched are prioritized for action according to degree of threat and recovery/conservation potential. Recovery/conservation goals are specified and the reasons for proposed actions are explained. Identifying measures for recovery or conservation was often difficult because the cause of decline or the threats to species were unknown or unclear. Better collation of relevant information would create a stronger evidence base, assist the provision of better advice, and therefore support better decision-making by managers. Application of the methodology to other marine species of conservation concern in a particular biogeographical or administrative area needs more meaningful lists than are currently used of species that are rare, scarce, in decline or threatened with decline. © 2012 John Wiley & Sons, Ltd.
Thompson P.M.,University of Aberdeen |
Hastie G.D.,SMRU Ltd |
Nedwell J.,Subacoustech Environmental Ltd. |
Barham R.,Subacoustech Environmental Ltd. |
And 4 more authors.
Environmental Impact Assessment Review | Year: 2013
Offshore wind farm developments may impact protected marine mammal populations, requiring appropriate assessment under the EU Habitats Directive. We describe a framework developed to assess population level impacts of disturbance from piling noise on a protected harbour seal population in the vicinity of proposed wind farm developments in NE Scotland. Spatial patterns of seal distribution and received noise levels are integrated with available data on the potential impacts of noise to predict how many individuals are displaced or experience auditory injury. Expert judgement is used to link these impacts to changes in vital rates and applied to population models that compare population changes under baseline and construction scenarios over a 25. year period. We use published data and hypothetical piling scenarios to illustrate how the assessment framework has been used to support environmental assessments, explore the sensitivity of the framework to key assumptions, and discuss its potential application to other populations of marine mammals. © 2013 The Authors.
Pirotta E.,SMRU Ltd |
Pirotta E.,University of St. Andrews |
Milor R.,Northumbria University |
Quick N.,SMRU Ltd |
And 7 more authors.
PLoS ONE | Year: 2012
Some beaked whale species are susceptible to the detrimental effects of anthropogenic noise. Most studies have concentrated on the effects of military sonar, but other forms of acoustic disturbance (e.g. shipping noise) may disrupt behavior. An experiment involving the exposure of target whale groups to intense vessel-generated noise tested how these exposures influenced the foraging behavior of Blainville's beaked whales (Mesoplodon densirostris) in the Tongue of the Ocean (Bahamas). A military array of bottom-mounted hydrophones was used to measure the response based upon changes in the spatial and temporal pattern of vocalizations. The archived acoustic data were used to compute metrics of the echolocation-based foraging behavior for 16 targeted groups, 10 groups further away on the range, and 26 non-exposed groups. The duration of foraging bouts was not significantly affected by the exposure. Changes in the hydrophone over which the group was most frequently detected occurred as the animals moved around within a foraging bout, and their number was significantly less the closer the whales were to the sound source. Non-exposed groups also had significantly more changes in the primary hydrophone than exposed groups irrespective of distance. Our results suggested that broadband ship noise caused a significant change in beaked whale behavior up to at least 5.2 kilometers away from the vessel. The observed change could potentially correspond to a restriction in the movement of groups, a period of more directional travel, a reduction in the number of individuals clicking within the group, or a response to changes in prey movement. © 2012 Pirotta et al.
Sayigh L.,Woods Hole Oceanographic Institution |
Quick N.,SMRU Ltd. |
Quick N.,University of St. Andrews |
Hastie G.,SMRU Ltd. |
And 3 more authors.
Marine Mammal Science | Year: 2013
Four short-finned pilot whales, Globicephala macrorhynchus, were tagged with digital acoustic recording tags (DTAGs) for a total of 30 h in the Bahamas during 2007. Spectrograms were made of all audible sounds, which were independently categorized by three observers. Of 4,098 calls, 1,737 (42%) were placed into 173 call types, which were defined as calls that occurred more than once. Of the 173 call types, 51 contained at least 10 calls (= 24), and were termed predominant call types (PCTs), which comprised 1,219 (70%) of categorized calls. PCTs tended to occur in sequences of the same call, which appeared to be produced by a single animal. However, matching interactions consisting of adjacent or overlapping calls of the same type were also observed, and some call types were recorded on more than one tag, suggesting that at least some calls are shared by members of a group or subgroup. These results emphasize the importance of categorizing calls before attempting to draw conclusions about call usage and possible effects of noise on vocal behavior. © 2012 by the Society for Marine Mammalogy.
Kaschner K.,Albert Ludwigs University of Freiburg |
Quick N.J.,SMRU Ltd |
Quick N.J.,University of St. Andrews |
Jewell R.,SMRU Ltd |
And 3 more authors.
PLoS ONE | Year: 2012
Knowledge of abundance, trends and distribution of cetacean populations is needed to inform marine conservation efforts, ecosystem models and spatial planning. We compiled a geo-spatial database of published data on cetacean abundance from dedicated visual line-transect surveys and encoded >1100 abundance estimates for 47 species from 430 surveys conducted worldwide from 1975-2005. Our subsequent analyses revealed large spatial, temporal and taxonomic variability and gaps in survey coverage. With the exception of Antarctic waters, survey coverage was biased toward the northern hemisphere, especially US and northern European waters. Overall, <25% of the world's ocean surface was surveyed and only 6% had been covered frequently enough (≥5 times) to allow trend estimation. Almost half the global survey effort, defined as total area (km2) covered by all survey study areas across time, was concentrated in the Eastern Tropical Pacific (ETP). Neither the number of surveys conducted nor the survey effort had increased in recent years. Across species, an average of 10% of a species' predicted range had been covered by at least one survey, but there was considerable variation among species. With the exception of three delphinid species, <1% of all species' ranges had been covered frequently enough for trend analysis. Sperm whales emerged from our analyses as a relatively data-rich species. This is a notoriously difficult species to survey visually, and we use this as an example to illustrate the challenges of using available data from line-transect surveys for the detection of trends or for spatial planning. We propose field and analytical methods to fill in data gaps to improve cetacean conservation efforts. © 2012 Kaschner et al.
Jewell R.,SMRU Ltd. |
Jewell R.,University of St. Andrews |
Thomas L.,University of St. Andrews |
Harris C.M.,University of St. Andrews |
And 5 more authors.
Marine Ecology Progress Series | Year: 2012
Measuring the effect of anthropogenic change on cetacean populations is hampered by our lack of understanding about population status and a lack of power in the available data to detect trends in abundance. Often long-term data from repeated surveys are lacking, and alternative approaches to trend detection must be considered. We utilised an existing database of linetransect survey records to determine whether temporal trends could be detected when survey effort from around the world was combined. We extracted density estimates for 25 species and fitted generalised additive models (GAMs) to investigate whether taxonomic, spatial or methodological differences among systematic line-transect surveys affect estimates of density and whether we can identify temporal trends in the data once these factors are accounted for. The selected GAM consisted of 2 parts: an intercept term that was a complex interaction of taxonomic, spatial and methodological factors and a smooth temporal term with trends varying by family and ocean basin. We discuss the trends found and assess the suitability of published density estimates for detecting temporal trends using retrospective power analysis. In conclusion, increasing sample size through combining survey effort across a global scale does not necessarily result in sufficient power to detect trends because of the extent of variability across surveys, species and oceans. Instead, results from repeated dedicated surveys designed specifically for the species and geographical region of interest should be used to inform conservation and management. © 2012 Inter-Research.
Bailey H.,SMRU Ltd. |
Bailey H.,University of Aberdeen |
Bailey H.,University of Maryland Center for Environmental Science |
Hammond P.S.,University of St. Andrews |
Thompson P.M.,University of Aberdeen
Journal of Experimental Marine Biology and Ecology | Year: 2014
Technological developments over the last 20. years have meant that telemetry studies have used a variety of techniques, each with different levels of accuracy and temporal resolution. This presents a challenge when combining data from these different tracking systems to obtain larger sample sizes or to compare habitat use over time. In this study, we used a Bayesian state-space modelling approach to integrate tracking data from multiple tag types and standardise position estimates while accounting for location error. Harbour seal (. Phoca vitulina) telemetry data for the Moray Firth, Scotland, were collated from three tag types: VHF, Argos satellite and GPS-GSM. Tags were deployed on 37 seals during 1989 to 2009 resulting in 37 tracks with a total of 2886 tracking days and a mean duration of 87. days per track. A state-space model was applied to all of the raw tracks to provide daily position estimates and a measure of the uncertainty for each position. We used this standardised tracking dataset to model their habitat use and preference, which was then scaled by the population size estimated from haul-out counts to give an estimate of the absolute number of harbour seals using different parts of the Moray Firth. As expected for a central place forager, harbour seals most frequently occurred in areas close to their inshore haul-out sites. However, our analyses also demonstrated consistent use of offshore foraging grounds, typically within 30. km of haul-out sites in waters <. 50. m deep. The use of these statistical models to integrate and compare different datasets is especially important for assessing longer-term responses to environmental variation and anthropogenic activities, allowing management advice to be based upon datasets that integrate information from all available tracking technologies. © 2013 Elsevier B.V.
Rosen D.A.S.,University of British Columbia |
Tollit D.J.,University of British Columbia |
Tollit D.J.,SMRU Ltd
Marine Ecology Progress Series | Year: 2012
Quantitative fatty acid signature analysis (QFASA) has been proposed as a technique for determining the long-term diet of animals. The method compares the fatty acid (FA) profiles of predators and potential prey items to estimate relative prey intake. We tested the assumptions of a key step in QFASA, the correction of predator FA signatures for metabolic processes through sets of calibration coefficients (CCs). We conducted long-term controlled feeding studies with captive Steller sea lions consuming herring and eulachon and northern fur seals consuming herring. We compared the results with data from harbour seals eating herring to evaluate the effects of phylogeny and prey type on individual CCs. Even within the limited extended dietary FA subset recommended for use by other researchers, we found that at least 41% of the CCs differed by family (otariid vs. phocid seals) and 58% differed by predator species (sea lion vs. fur seal), suggesting that CCs may be highly species-specific. We also found that 64% of the CCs differed by prey type (sea lions consuming herring vs. eulachon), which raises some fundamental implementation issues. We also found significant differences in diet predictions when the herring- and eulachon-derived sets of CCs were applied to an actual multi-species diet. CCs are presently used as a simple mathematical attempt to describe potentially complex biochemistry. The results of this study raise questions regarding the validity of using CCs derived from an alternative predator species, and highlight some fundamental issues regarding QFASA methodology that need to be addressed through further controlled studies. © Inter-Research 2012.
Leaper R.,International Fund for Animal Welfare |
Burt L.,University of St. Andrews |
Gillespie D.,University of St. Andrews |
Macleod K.,SMRU Ltd.
Journal of Cetacean Research and Management | Year: 2010
Photogrammetric systems using video cameras were used to measure radialdistances to sightings during the SCANS-II, CODA and SOWER surveys. These surveys included sightings of a variety of species from harbour porpoise, at distances of a few hundred metres, to large baleen whales at distances greater than 10km. A total of 910 initial sightings with estimated distances from reticles and measured distances from video, using 7 × 50 (636) or 25 × 'Big Eye' (274) binoculars, were compared. Bearings to sightings were also measured from still images. The CV, RMSE in distances varied between 0.19 and 0.33 for reticle binoculars. Comparisons of measured distances to simultaneous sightings by other observers using naked eye gave a CV RMSE of 0.39 for naked eye estimates. There was a consistent, non-linear pattern in all data sets, of over-estimating close distances to sightings of surfacing cetaceans and under-estimating those further away. However, this pattern was not evident from the distance experiments on SOWER to fixed targets which also had a much lower variance (CV RMSE= 0.13). Bearing data from SCANS-II and CODA showed around 5% of estimates had gross errors greater than 20° that were attributed to mistakes. For the remaining values, RMS errors were in the range 5.7°-7.2° for SCANS-II and CODA and 4.9° for SOWER. Both distance and angle errors will make a substantial contribution to the variance of abundance estimates and simulated data showed that the observed non-linear nature of distance errors may cause considerablebias even when linear regressions might suggest little bias. There still remain technological challenges inoperating complex electronic systems at sea to measure distances and bearings, but investment in these methods should be a cost effective way of reducing bias and improving precision of cetacean abundance estimates.
PubMed | SMRU Ltd
Type: Journal Article | Journal: PloS one | Year: 2012
Some beaked whale species are susceptible to the detrimental effects of anthropogenic noise. Most studies have concentrated on the effects of military sonar, but other forms of acoustic disturbance (e.g. shipping noise) may disrupt behavior. An experiment involving the exposure of target whale groups to intense vessel-generated noise tested how these exposures influenced the foraging behavior of Blainvilles beaked whales (Mesoplodon densirostris) in the Tongue of the Ocean (Bahamas). A military array of bottom-mounted hydrophones was used to measure the response based upon changes in the spatial and temporal pattern of vocalizations. The archived acoustic data were used to compute metrics of the echolocation-based foraging behavior for 16 targeted groups, 10 groups further away on the range, and 26 non-exposed groups. The duration of foraging bouts was not significantly affected by the exposure. Changes in the hydrophone over which the group was most frequently detected occurred as the animals moved around within a foraging bout, and their number was significantly less the closer the whales were to the sound source. Non-exposed groups also had significantly more changes in the primary hydrophone than exposed groups irrespective of distance. Our results suggested that broadband ship noise caused a significant change in beaked whale behavior up to at least 5.2 kilometers away from the vessel. The observed change could potentially correspond to a restriction in the movement of groups, a period of more directional travel, a reduction in the number of individuals clicking within the group, or a response to changes in prey movement.