[MARMAM] Abstracts - Journal of Cetacean Research and Management - Vol 11(3)
dagmar_fertl at hotmail.com
Wed Aug 17 20:58:27 PDT 2011
Dear Marmam and ECS-mailbase subscribers,
Apologies to those of you who will receive duplicate emails due to cross-posting. The following are abstracts from the most recent issue (Volume 11, issue 3, 2010) of the Journal of Cetacean Research and Management.
The International Whaling Commission (IWC) publishes The Journal of Cetacean Research and Management thrice yearly (Spring, Autumn, and Winter), with at least one supplement that will contain the full report of the IWC Scientific Committee. The following is posted on behalf of the IWC and the journal editor.
Further information can be found at: http://www.iwcoffice.org/publications/JCRM.htm. A guide for authors is included in the first volume of each issue and on the IWC website: http://www.iwcoffice.org/publications/authorsguide.htm.
Contact information is provided for the corresponding author for each article. Please do not contact the listserve editors or me for pdfs or copies of the articles; contact emails for authors are presented below. Thank you for your continued interest in the journal and abstract postings.
Gillespie, D., R. Leaper, J. Gordon, and K. MacLeod. 2010. An integrated data collection system for line transect surveys. Journal of Cetacean Research and Management 11(3):217-227.
Contact e-mail: dg50 at st-andrews.ac.uk
A computer based system for the collection of line transect survey data is described. The primary goals of the system were to measure (rather than estimate) distances and angles wherever possible, to provide accurate time-stamps for surfacing events as an aid to duplicate identification and to facilitate accurate data collection by using computers to automate data collection wherever possible. Distance and angle measurements were made using established photogrammetric techniques. Collection of photogrammetric data from video data was automated and included a system of data buffering so that several seconds of data prior to each observer sighting could be captured. An additional goal of the system was to eliminate the need for post-cruise data entry and validation through the use of on-board data validation software. The system was successfully used during the 2005 SCANS-II and the 2007 CODA surveys.
Leaper, R., L. Burt, and D. Gillespie, and K. MacLeod. 2010. Comparisons of measured and estimated distances and angles from sighting surveys. Journal of Cetacean Research and Management 11(3):229-37.
Contact e-mail: Russell at ivyt.demon.co.uk
Photogrammetric systems using video cameras were used to measure radial distances 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 7x 50 binoculars (636) or 25x ‘Big Eyes’ (274), were compared. Bearings to sightings were also measured from still images. The CV of the Root Mean Square Error (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 of the 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 farther 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 degrees that were attributed to mistakes. For the remaining values, RMS errors were in the range 5.7 degrees – 7.2 degrees for SCANS-II and CODA and 4.9 degrees 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 considerable bias even when linear regressions might suggest little bias. There still remain technological challenges in operating 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.
Koski, W.R., P. Abgrall, and S.B. Yazvenko. 2010. An inventory and evaluation of unmanned aerial systems for offshore surveys of marine mammals. Journal of Cetacean Research and Management 11(3):239-247.
Contact e-mail: bkoski at lgl.com
A literature review, internet searches and communications with personnel working with unmanned aerial systems (UAS) were used to identify the capabilities of UAS throughout the world. We assessed their ability to replace manned aerial surveys for marine mammals, sea turtles and sea birds and to monitor in real time, sea ice and other physical features that might influence marine mammal distribution.
The vast majority of the systems identified were either too expensive or their capabilities did not meet minimum standards necessary to perform the tasks required of them in real time. Eight systems were identified that might be able to perform some of the desired tasks. Several other systems had similar capabilities but had not been tested or would require upgrades. Installation of high-definition (HD) video and better stabilisation systems would improve UAS performance. It is recommended that development of HD video with real-time data transmission and improved stabilisation systems for UAS be pursued and that side-by-side comparisons of a few of the best systems be conducted.
Selland Kleppe, T., H.J. Skaug, and H. Okamura. 2010. Asymptotic bias of the hazard probability model under model mis-specification. Journal of Cetacean Research and Management 11(3):249-252.
Contact e-mail: skaug at math.uib.no
We compare the sensitivity of the estimated effective strip half-width with respect to choice of hazard probability function (Q). This is done by fitting the model under an erroneous assumption about the parametric form of Q, and comparing the estimated and true effective strip half-width. An ‘infinite sample size’ setting is employed, where fitting the model by maximum likelihood amounts to minimizing the Kullback Leibler distance between the assumed and true models. The experiment is carried out in a situation that is relevant to minke whale sighting surveys both in the Antarctic and in the northeastern Atlantic. It is found that the hazard probability model is fairly robust with respect to the choice of parametric class for Q. The largest observed bias in the resulting effective strip half-width is less than 10%, while for most situations there is almost no bias.
Schwarz, L.K., T. Gerrodette, and F.I. Archer. 2010. Comparison of closing and passing mode from a line-transect survey of delphinids in the eastern Tropical Pacific Ocean. Journal of Cetacean Research and Management 11(3):253-265.
Contact e-mail: schwarz at biology.ucsc.edu
Line-transect ship surveys are the primary method used to estimate abundance of pelagic cetaceans. However, survey methods are often modified from traditional methods because observers must approach cetacean groups to identify species and estimate group size. Returning to the trackline after approaching a school dramatically reduces the amount of effective survey time, so ships often resume survey effort at the sighting but parallel to the original trackline (closing mode). Survey effort is no longer independent of group locations, and it is unclear how such methodological modifications affect overall abundance estimates. This research presents the results of a study designed to determine the effects of closing mode methods on abundance estimation for cetacean species in the eastern tropical Pacific. Species identification and group size estimation in closing mode are compared with results using survey techniques where the ship does not approach or slow down to investigate a sighting (passing mode). Both empirical data and simulations were used to compare group encounter rates in the two modes and to better understand the mechanisms that might lead to an encounter rate bias in closing mode. As seen in similar studies, observers are able to identify to the species level less frequently in passing mode (81% vs 57% of sightings), and point estimates of delphinid group size were 58% lower in passing mode than closing mode at distances between 1.0 and 5.5km from the trackline. In addition, uncertainty in group size both within and between observers was higher in passing mode. Closing mode delphinid group encounter rates were generally 20–25% lower than passing mode delphinid group encounter rates. Simulations showed the empirically lower encounter rates in closing mode are due to a loss in detection probability caused by the stop-start nature of the survey method. The closing mode encounter rate bias is greater when groups are in fewer and/or tighter clusters and when overall group density is higher. Methodological adjustments and analytical solutions to improve group size estimation and species identification in passing mode and reduce closing mode encounter rate bias are analytically complex and would also result in the loss of important additional life history data. Nevertheless, such avenues should be explored further.
Garrison, L.P., A. Martinez, and K. Maze-Foley. 2010. Habitat and abundance of cetaceans in Atlantic Ocean continental slope waters off the eastern USA. Journal of Cetacean Research and Management 11(3):267-277.
Contact e-mail: Lance.Garrison at noaa.gov
This study quantifies the abundance and spatial distribution of the cetacean community occupying continental shelf edge and inner continental slope waters along the US southeast Atlantic coast. A shipboard visual line-transect survey was conducted between June and August of 2004 that included effort in waters >50m deep encompassing the shelf break and inner continental slope off the US east coast between 28 degrees N and 38 degrees N latitude. The abundance of nine cetacean taxa was estimated using line-transect distance analysis and an independent observer approach to correct for visibility bias. Canonical correspondence analysis was used to examine the spatial distribution of the cetaceans encountered during the survey as a function of surface temperature, surface salinity, surface fluorescence, bottom depth, and bottom slope. The abundance estimates for most species were much higher than those from a study of the area conducted in 1998. This is primarily due to increased coverage of the shelf-break region and correction for visibility bias. The multivariate analysis indicated four distinct groups of cetaceans that partitioned habitat as a function of salinity, depth, and a latitudinal gradient. These groups were associated with specific water masses and hydrographic features including mid-Atlantic shelf waters (Group I), the shelf break (Group II), mid-Atlantic slope waters (Group III), and south Atlantic slope water (Group IV). Areas where water masses converge such as the continental shelf break along the mid-Atlantic and near Cape Hatteras, North Carolina are therefore areas of both high diversity and density of cetaceans.
Lauriano, G., S. Panigada, R. Canneri, M. Manca Zeichen, and G. Notarbartolo-Di Sciara. 2010. Abundance estimate of striped dolphins (Stenella coeruleoalba) in the Pelagos Sanctuary (NW Mediterranean) by means of line transect survey. Journal of Cetacean Research and Management 11(3):279-283.
Contact e-mail: giancarlo.lauriano at isprambiente.it
To assess cetacean densities in the Pelagos Sanctuary for Mediterranean Marine Mammals, a Marine Protected Area (MPA) specifically designated to protect cetaceans, a survey was carried out in the Ligurian-Provençal Sea (NW Mediterranean) in August 2008. An area of 58,000 km2 was surveyed in eight days with equally spaced zigzag transects, covering 1,255 km in favorable conditions. Tracklines were designed using Distance 5.0 to allow for homogeneous coverage probability over the selected area. Fifty three sightings of four cetacean species were made: striped dolphins (n=37), fin whales (n=12), sperm whales (n=3) and Cuvier’s beaked whales (n=1). Estimates of abundance were obtained using Distance 5.0. The estimated dolphin abundance was 13,232 (CV=35.55; 95% C.I.=6,640.0-26,368), with a density of 0.23 individuals km-1 (CV=35.55; 95% C.I.=0.11-0.45). No fin whale abundance was possible due to the small sample size. The point estimate of the 2008 striped dolphin abundance estimate was almost half of that of a survey conducted in 1992 by Forcada and colleagues (1995) in the same area with comparable effort, platform and methodology (25,614; CV=25.3; 95% C.I.=15,377-42,658); nevertheless, the difference was not statistically significant. These results strongly suggest the need for further systematic monitoring in the Sanctuary and in the surrounding areas, in order to assess striped dolphin abundance, spatial and temporal trends.
Montero-Cordero, A. and J. Lobo. 2010. Effect of tourist vessels on the behaviour of the pantropical spotted dolphin, Stenella attenuata, in Drake Bay and Caño Island, Costa Rica. Journal of Cetacean Research and Management 11(3):285-291.
Contact e-mail: amontero at fundacionketo.org
Despite the exponential increase in whalewatching activities in Costa Rica, little is known about its biological impact on resident coastal populations of dolphins in the country. Globally, this activity has brought economic benefits to the communities where it is practiced and in some cases, has played an important role in conservation of these mammals. However, when intensively practiced, this activity may significantly affect the animals, since its success depends on following cetaceans for extended periods of time. This study was conducted during the 2004–2005 and 2005–2006 dry seasons, to examine the biological factors associated with this activity in two areas where it is intensively practiced: Drake Bay and Caño Island. Three strip transects were followed within a high (vessel) traffic area. The pantropical spotted dolphin was studied through instant sampling, every two minutes. Sighting density of dolphins accompanied by tourist boats was greater within 3km of the island compared to the average density in the whole study area. Dolphins reacted negatively to those boats that did not follow at least one of the rules of boat handling in the current existing national regulation for whalewatching guidelines. Furthermore, a logistic regression analysis showed that feeding and resting are less likely to occur in the presence of tourist boats. These two behaviours are extremely important and mishandled boats could cause the spotted dolphin to leave this area if these flaws continue. Due to the lack of economic resources and staff from state institutions in Costa Rica, the reinforcement of the Whalewatching Executive Decree 32495 (2005) may be more efficient with ‘bottom up’ control, where community representatives control their own resources in conjunction with government oversight.
Frost, K.J., and R.S. Suydam. 2010. Subsistence harvest of beluga or white whales (Delphinapterus leucas) in northern and western Alaska, 1987-2006. Journal of Cetacean Research and Management 11(3):293-299.
Contact e-mail: kjfrost at hawaii.rr.com
Four stocks of beluga or white whales (Delphinapterus leucas) are hunted by Alaska Natives in northern and western Alaska. These are the Beaufort Sea, eastern Chukchi Sea, eastern Beting Sea and Bristol Bay stocks. Since 1987, the Alaska Beluga Whale Committee has monitored the subsistence harvests of belugas from these stocks. During the 20 year period, the total landed harvest for the four stocks combined (adjusted for years with missing data) ranged form 208 in 1995 to 494 in 1988, with a 20 year average of 323 per year. For individual stocks the average annual landed harvests for 1987-2006 were: Beaufort Sea – 41; Chukchi Sea – 62; eastern Bering Sea – 191; and Bristol Bay – 20. There was no significant long-term trend (p>0.05) in the rate of harvesting for any stock from 1987-2006. Average landed harvests relative to estimated stock size were: 0.1% for the Beaufort Sea (0.4% including belugas harvested from the Beaufort Sea stock by Canadian hunters); 1.7% for the eastern Chukchi Sea; 1.1% for the eastern Bering Sea; and 1.1% for Bristol Bay. The success of beluga harvest monitoring in Alaska is due to the cooperation of beluga hunters from more than 40 small coastal communities who report their harvests to the Alaska Beluga Whale Committee (ABWC). Through the ABWC, beluga hunters have been able to formalize their role in managing their subsistence resources.
Minton, G., T. Collins, K. Findlay, and R. Baldwin. 2010. Cetacean distribution in the coastal waters of the Sultanate of Oman. . Journal of Cetacean Research and Management 11(3):301-313.
Contact e-mail: Gianna.Minton at gmail.com
Small boat surveys were conducted between 2000 and 2003 in three main regions of Oman’s coastal waters: Muscat, the Gulf of Masirah and Dhofar. Survey data were analysed to calculate abundances of the seven most frequently encountered species in these areas. These include (in order of frequency) bottlenose dolphins (Tursiops sp.), long-beaked common dolphins (Delphinus capensis), humpback whales (Megaptera novaeangliae), spinner dolphins (Stenella longirostris), Indo-Pacific humpback dolphins (Sousa chinensis), Bryde’s whales (Balaenoptera sp.) and Risso’s dolphins (Grampus griseus). Other species observed include false killer whales (Pseudorca crassidens), blue whales (Balaenoptera musculus), rough-toothed dolphins (Steno bredanensis) and unidentified beaked whales. Encounter rates per distance searched were plotted by 0.1 x 0.1 degree grid cell, giving an indication of relative abundances and key areas of habitat used by each of the seven most frequently encountered species. These plots demonstrate that the nearshore areas of the Gulf of Masirah, as well as the coastal waters of Dhofar, are areas of concentration for the Arabian Sea’s recently designated Endangered subpopulation of humpback whales, as well as Indo-Pacific humpback dolphins, which are considered Near Threatened on the IUCN Red List of Threatened Species. The results presented here provide valuable baseline data for future research and help to inform conservation management efforts that are required to address the highly vulnerable status of the humpback whale and Indo-Pacific humpback dolphin populations in question.
Van Waerebeek, K., R. Leaper, A.N. Bakker, V. Papastavrou, D. Thiele, K. Findlay, ,G. Donovan, and P. Ensor. 2010. Odontocetes of the Southern Ocean Sanctuary. Journal of Cetacean Research and Management 11(3):315-346.
Contact e-mail: corewam at gmail.com
Twenty-eight odontocete species were identified as occupying sub-Antarctic and Antarctic habitat covered by the 1994 IWC-established Southern Ocean Sanctuary. Toothed whales evidently play an important part in the Antarctic polar ecosystem. Twenty-one species are autochthonus in showing a regular, apparently year-round, presence in the Sanctuary: Physeter macrocephalus, Kogia breviceps, Orcinus orca, Globicephala melas edwardii, Pseudorca crassidens, Lagenorhynchus cruciger, Lagenorhynchus obscurus, Lissodelphis peronni, Cephalorhynchus commersonii, Cephalorhynchus hectori, Tursioips truncatus, Delphinus delphis, Phocoena dioptrica, Hyperoodon planifrons, Berardius arnuxii, Ziphius cavirostris, Tasmacetus shepherdi, Mesoplodon layardii, Mesoplodon traversii, Mesoplodon grayi, Mesoplodon bowdoini and Mesoplodon hectori. Six species are considered vagrants into the Sanctuary: Kogia simus, Grampus griseus, Steno bredanensis, Mesoplodon peruvianus, Mesoplodon densirostris and Mesoplodon mirus. However, vagrant status of these three mesoplodonts is only provisionally assigned, considering that improved knowledge of diagnostic features of beaked whales should, as in recent years, continue to facilitate at-sea identification. Two species are considered as having a “contiguous’ range (records less than 2 degrees north of Sanctuary boundaries): Mesoplodon ginkgodens (at 39 degrees S) and Mesoplodon mirus (at 38 degrees 24’S). The habitual southern range of at least four odontocetes extends significantly farther poleward than expected, G. melas edwardii is regularly encountered south of the Antarctic Polar Front, much like M. grayi which is known to reach the Ross Sea ice edge (ca. 67 degrees S). Z. cavirostris and L. obscurus cross the Polar Front occasionally. The distribution of M. peruvianus and M. traversii and their relation to SST are unclear. Their southernmost records, 42 degrees 31’S and 44 degrees 17’S respectively, may either be extralimital or, more likely, reflect ordinary austral range. Temporally non-aligned distribution patterns of Hyperoodon planifrons in Antarctic and South African waters may suggest stock segregation.
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