[MARMAM] Contents and Abstracts - IWC JCRM Special Issue 3- Humpback Whales: Status in the Southern Hemisphere

Dagmar Fertl dagmar_fertl at hotmail.com
Wed Aug 8 21:41:47 PDT 2012




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 Special Issue 3 of the Journal of Cetacean Research and Management, entitled Humpback Whales: Status in the Southern Hemisphere, edited by N. Gales, J.L. Bannister, K. Findlay, A. Zerbini, and G.P. Donovan, with a publication date of 2011.
 
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. Thank you for your continued interest in the journal and abstract postings.
 
With regards,
Dagmar Fertl
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International Whaling Commission. 2011. Report of the Workshop on the Comprehensive Assessment of Southern Hemisphere Humpback Whales, 4-7 April 2006, Hobart, Tasmania. Journal of Cetacean Research and Management (Special Issue 3):5-50.
 
Contents include: assessment procedures; review of stock structure, distribution and movements; catch information; estimates of recent abundance and observed trends; biological parameters; threats; environmental parameters; assessments and projections; and conclusions and recommendations to the Scientific Committee. Annexes include: discovery mark summary; assessment of genetic differentiation between Breeding Stocks A, B, C and X, and Areas I, II and III based on mtDNA; consideration of observed male-skewed sex ratios in humpback whales; and considerations for matching large photo-identification catalogues; recommendations for each breeding stock.
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Branch, T.A.* 2011. Humpback abundance south of 60°S from three complete circumpolar sets of surveys.  Journal of Cetacean Research and Management (Special Issue 3):53-69.
 
*Contact e-mail: tbranch at uw.edu
 
Austral summer estimates of abundance are obtained for humpback whales (Megaptera novaeangliae) in the Southern Ocean from the IWC’s IDCR and SOWER circumpolar programmes. These surveys have encircled the Antarctic three times: 1978/79–1983/84 (CPI), 1985/86–1990/91 (CPII) and 1991/92–2003/04 (CPIII), criss-crossing strata totalling respectively 64.3%, 79.5% and 99.7% of the open-ocean area south of 60°S. Humpback whales were absent from the Ross Sea, but were sighted in all other regions, and in particularly high densities around the Antarctic Peninsula, in Management Area IV and north of the Ross Sea. Abundance estimates are presented for each CP, for Management Areas, and for assumed summer feeding regions of each Breeding Stock. Abundance estimates are negatively biased because some whales on the trackline are missed and because some humpback whales are outside the survey region. Circumpolar estimates with approximate midpoints of 1980/81, 1987/88 and 1997/98 are 7,100 (CV = 0.36), 10,200 (CV = 0.30) and 41,500 (CV = 0.11). When these are adjusted simply for unsurveyed northern areas, the estimated annual rate of increase is 9.6% (95% CI 5.8–13.4%). All Breeding Stocks are estimated to be increasing but increase rates are significantly greater than zero only for those on the eastern and western coasts of Australia. Given the observed rates of increase, the current total Southern Hemisphere abundance is greater than 55,000, which is similar to the summed northern breeding ground estimates (~60,000 from 1999–2008). Some breeding ground abundance estimates are far greater, and others far lower, than the corresponding IDCR/SOWER estimates, in a pattern apparently related to the latitudinal position of the Antarctic Polar Front. 
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Best, P.B.* 2011. A note on the age at sexual maturity of humpback whales. Journal of Cetacean Research and Management (Special Issue 3):71-73.
 
*Contact e-mail: pbest at iziko.org.za
 
The conclusion of researchers in the 1950s that humpback whales reached sexual maturity at about age five was largely influenced by their interpretation of baleen tracings, and to achieve consistency with these tracings the accumulation rate of ear plug laminations (growth layer groups: GLGs) was assumed to be two per year. However, ovulation and natural mortality rates calculated by these researchers under the same assumption produced estimates that are difficult to reconcile with other biological data or with more recent estimates using individual re-sighting data. Such disparities are reduced or disappear when an annual accumulation rate is used, in which case their ear plug data would have indicated a mean age at sexual maturity of 9–11 years. Recent estimates of the age of female humpback whales at first calving using longitudinal studies of photo-identified individuals have produced conflicting results, some (from southeastern Alaska) being compatible with the earlier age-determination studies, others (from the Gulf of Maine) suggesting a much younger age. 
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Matsuoka, K., T. Hakamada, H. Kiwada, H. Murase, and S. Nishiwaki. 2011. Abundance estimates and trends for humpback whales (Megaptera novaeangliae) in Antarctic Areas IV and V based on JARPA sightings data. Journal of Cetacean Research and Management (Special Issue 3):75-94.
 
*Contact e-mail: matsuoka at cetacean.jp
 
Sighting survey data from the Japanese Whale Research Program under Special Permit in the Antarctic (JARPA) are analysed to obtain abundance estimates for humpback whales (Megaptera novaeangliae) south of 60°S. The surveys were conducted during the 1989/90–2004/05 austral summer seasons (mainly in January and February); the survey areas alternated between Area IV (70°E–130°E) and Area V (130°E to 170°W) each year. Primary sighting effort totalled 293,811 n.miles over 6,188 days. Abundance estimates are obtained using standard line transect analysis methods and the program DISTANCE. Estimated densities of humpback whales were highest east of the Kerguelen Plateau (80°E–120°E). Abundance estimates for Area IV range from 2,747 (CV = 0.153) in 1993/94 to 31,134 (CV = 0.123) in 2001/02, while those for Area V range from 602 (CV = 0.343) in 1990/91 to 9,342 (CV = 0.337) in 2004/05. The estimates are similar to those obtained from the International Whaling Commission’s IDCR-SOWER surveys, which were conducted in Area IV (in 1978/79, 1988/89 and 1998/99) and in Area V (in 1980/81, 1991/92 and 2001/02–2003/04). Estimated annual rates of increase for Area IV (16.4%; 95% CI = 9.5–23.3%) and Area V (12.1%; 95% CI = 1.7–22.6%) are also similar to those obtained from the IDCR-SOWER surveys. The total abundance in Areas IV and V based on the most recent JARPA surveys (2003/04 and 2004/05 combined) is 37,125 (95% CI = 21,349–64,558); the confidence interval incorporates estimated additional variance. Results of several sensitivity tests are presented that suggest that estimates of abundance and trends are not appreciably affected by factors such as different approaches to deal with survey coverage (which in some cases was poor or included gaps). Changes in the order in which survey strata were covered and potential effects are investigated using a nested GLM approach; a QAIC model selection criterion suggests a preference for not attempting to adjust for such changes. Under various sensitivity approaches, the point estimates of increase rates are not greatly affected for Area IV. Although they drop by typically a half for most approaches for Area V, they nevertheless remain within the confidence limits of the base case estimate of 12.1% per year (95% CI = 1.7–22.6%). The presented results thus suggest that the estimated abundance of humpback whales in Area IV has increased rapidly. Although there is also an increase indicated for Area V, it is neither as rapid nor as precisely estimated. Taking these results together with the similar rates of increase estimated from coastal surveys off western and eastern Australia for Breeding Stocks D and E respectively, and given demographic limitations on the increase rates possible for closed populations of humpback whales, the hypothesis is advanced that whales from Breeding Stock E may have shifted their feeding distribution westward as their numbers have increased, perhaps to take advantage of the higher densities of krill to be found to the west. 
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Allen, J.,* C. Carlson, and P.T. Stevick. 2011. A description and summary of the Antarctic Humpback Whale Catalogue. Journal of Cetacean Research and Management (Special Issue 3):95-99.
 
*Contact e-mail: jallen at coa.edu
 
The Antarctic Humpback Whale Catalogue (AHWC) is an international collaborative project investigating movement patterns of humpback whales in the Southern Ocean and corresponding lower latitude waters. The collection contains records contributed by 261 researchers and opportunistic sources. Photographs come from all of the Antarctic management areas, the feeding grounds in southern Chile and also most of the known or suspected low-latitude breeding areas and span more than two decades. This allows comparisons to be made over all of the major regions used by Southern Hemisphere humpback whales. The fluke, left dorsal fin/flank and right dorsal fin/flank collections represent 3,655, 413 and 407 individual whales respectively. There were 194 individuals resighted in more than one year, and 82 individuals resighted in more than one region. Resightings document movement along the western coast of South America and movement between the Antarctic Peninsula and western coast of South America and Central America. A single individual from Brazil was resighted off South Georgia, representing the first documented link between the Brazilian breeding ground and any feeding area. A second individual from Brazil was resighted off Madagascar, documenting long distance movement of a female between non-adjacent breeding areas. Resightings also include two matches between American Samoa and the Antarctic Peninsula, documenting the first known feeding site for American Somoa and setting a new long distance seasonal migration record. Three matches between Sector V and eastern Australia support earlier evidence provided by Discovery tags. Multiple resightings of individuals in the Antarctic Peninsula during more than one season indicate that humpback whales in this area show some degree of regional feeding area fidelity. The AHWC provides a powerful non-lethal and non-invasive tool for investigating the movements and population structure of the whales utilising the Southern Ocean Sanctuary. Through this methodical, coordinated comparison and maintenance of collections from across the hemisphere, large-scale movement patterns may be examined, both within the Antarctic, and from the Antarctic to breeding grounds at low latitudes. 
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Cotté, C.,* and C. Guinet. 2011. The importance of seasonal ice zone and krill densities in the historical abundance of humpback whale catches in the Southern Ocean. Journal of Cetacean Research and Management (Special Issue 3):101-106.
 
*Contact e-mail: cecotte at cebc.cnrs.fr
 
Humpback whale populations in the Southern Hemisphere were dramatically reduced by the whaling industry. A comprehensive whaling dataset was used in an analysis of circumpolar abundance of humpback whale catches relative to contemporary densities of its preferred prey, Antarctic krill, and to a major dynamic feature of the marine ecosystem, the summer seasonal ice zone (SSIZ) derived from southernmost whaling locations. The circumpolar abundance of catches derived only from pelagic data, i.e. about 30% of the total humpback whale catches in the Southern hemisphere, was found to be only marginally related to krill density. However, the total abundance of catches – from pelagic operations and land stations, from high and low latitudes – was found to be more related to SSIZ than to krill density, especially when excluding the highly dynamic west Atlantic region where the circulation probably drives the ecosystem. A large SSIZ is likely to provide a favourable feeding ground for humpback whales, given their high energy requirements and because of its predictability and the prey aggregation processes occurring there. 
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Secchi, E.R.*, L. Dalla Rosa, P.G. Kinas, R.F. Nicolette, A.M.N. Rufino, and A.F. Azevedo. 2011. Encounter rates and abundance of humpback whales, Megaptera novaeangliae, in the Gerlache and Bransfield Straits, Antarctic Peninsula. Journal of Cetacean Research and Management (Special Issue 3):107-111.
 
*Contact e-mail: edu.secchi at furg.br
 
During the austral summer of 2006, the Projeto Baleias/Brazilian Antarctic Program (PROANTAR) conducted ship surveys for estimating whale encounter rates and abundance in Gerlache and Bransfield Straits, westward of the Antarctic Peninsula (edge between IWC Areas I and II). The encounter rate was higher in the Bransfield Strait (0.32 groups n. mile–1; 95% CI: 0.26–0.39) than in the Gerlache Strait (0.24 groups n. mile–1; 95% CI: 0.13–0.44), though the difference was not statistically evident. An abundance estimate using conventional distance sampling methods was computed only for the Bransfield Strait. The perpendicular distance data was best fitted by the half-normal model without adjustments. Derived abundance for the surveyed area was 865 humpback whales (95% CI =656–1,141; CV = 14.13). This area represents only a small fraction of the Stock G feeding ground. 
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Zerbini, A.N., A. Andriolo, M.P. Heide-Jørgensen, S.C. Moreira, J.L. Pizzorno, Y.G. Maia, G.R. VanBlaricom, and D.P. DeMaster. 2011. Migration and summer destinations of humpback whales (Megaptera novaeangliae) in the western South Atlantic Ocean. Journal of Cetacean Research and Management (Special Issue 3):113-118.
 
*Contact e-mail: alex.zerbini at noaa.gov
 
Southern Hemisphere humpback whales (Megaptera novaeangliae) migrate from wintering grounds in tropical latitudes to feeding areas in the Antarctic Ocean. In 2003 and 2005, satellite transmitters were deployed on humpback whales on their wintering grounds off the eastern coast of South America (Breeding Stock A). Seven whales were tracked for a period of 16 to 205 days travelling between 902 and 7,258km. The tracks of these whales provided partial or full information on the migratory schedule, migration routes and location of the feeding ground in the Southern Oceans. Whales departed from the coast of Brazil from late October to late December between 20° and 25°S and gradually moved away from the South American coast as they moved towards high latitudes. They followed a somewhat direct, linear path, with an approximate geographic heading of 170°. Satellite telemetry data indicated that the migratory corridors are restricted to a relatively narrow (~500–800km) strip in the South Atlantic Ocean. Migration speed to the feeding grounds averaged 80.2km/day and lasted from 40–58 days. Four individuals arrived at the feeding ground located to the north of the South Sandwich Islands, where they were tracked up to 102 days. Movements in this area were erratic at a mean travelling speed of 22.3km/day. Satellite telemetry data indicate that the main feeding grounds for the population wintering off eastern South America lie between 22°W and 33°W and in the southern South Atlantic Ocean south of the Antarctic Convergence but north of 60°S. This is only partially consistent with the currently proposed stock boundaries for this population on the feeding grounds. 
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Leaper, R.*, S. Peel, D. Peel, and N. Gales. 2011. Exploring the assumptions of multi-stock assessment models for humpback whales (Megaptera novaeangliae) in the Southern Hemisphere: using Breeding Stocks D and E as an example. Journal of Cetacean Research and Management (Special Issue 3):119-128.
 
*Contact e-mail: rebecca.leaper at uta.edu.au
 
There is potential value in exploring multi-stock models to address situations where humpback stocks are mixing. However, sensitivity to the assumptions underlying these models has yet to be fully explored. Using a simple simulation approach, the assumptions of a population model that allows for mixing of humpback whale (Megaptera novaeangliae) stocks D and E on feeding areas has been explored by relaxing the assumptions of the original Johnston and Butterworth model in a number of plausible ways. First the ability of the model to estimate parameters was checked for a situation where simulated data are generated from an underlying model of exactly the same form for which the actual values of these parameters are known (Scenario 1). Then the ability of the model to estimate these parameters when alternative forms and assumptions were used for the underlying model generating the data was investigated. Specifically, stocks were allowed to mix non-uniformly across each feeding area and catch was non-uniformly distributed across each feeding area (Scenario 2). The consequences of density dependence implemented on feeding rather than breeding areas (Scenario 3) were also examined. The original mixing model was robust to alternate mixing and catch allocation scenarios in all but one of the simulations, but when density dependence acted at the level of the feeding rather than the breeding areas, the model produced estimates that were quite different from the underlying population. It is recommend that the inclusion of density dependence on feeding areas in models that allow for mixing of whales on these grounds be investigated further. 
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Zerbini, A.N., E.J. Ward, P.G. Kinas, M.H. Engel, and A. Andriolo. 2011. A Bayesian assessment of the conservation status of humpback whales (Megaptera novaeangliae) in the western South Atlantic Ocean (Breeding Stock A). Journal of Cetacean Research and Management (Special Issue 3):131-144.
 
*Contact e-mail: alex.zerbini at noaa.gov
 
The population of humpback whales (Megaptera novaeangliae) wintering off the eastern coast of South America is referred to by the International Whaling Commission as ‘Breeding Stock A’ (BSA). This population was heavily exploited in 20th century modern commercial whaling operations. After more than 30 years of protection, its present status remains unknown. A deterministic sex and age-aggregated population dynamics model was used to estimate the pre-exploitation population size (K), the maximum net recruitment rate (rmax), the maximum depletion level (Nmin/K), and other quantities of interest of BSA. Input data included modern whaling catch series, absolute estimates of abundance, observed growth rates and indices of relative abundance. A Bayesian statistical method was used to calculate probability distributions for the model parameters. Prior distributions were set on rmax – an uninformative (Uniform [0, 0.106]) and an informative (Normal [0.067, 0.042]) – and on the population size in 2005 – N2005 (Uniform [500, 22,000]). A total of 10,000 samples were used to compute the joint posterior distribution of the model parameters using the Sampling-Importance-Resampling algorithm. Sensitivity of model outputs to the priors on rmax, a genetic constraint, data inclusion and catch allocation scenarios was investigated. Medians of the posterior probability distributions of quantities of interest for the base case scenario were: rmax = 0.069 (95% probability intervals [PI] = 0.013–0.104), K = 24,558 (95% PI = 22,791–31,118), Nmin/K = 2% (PI = 0.31%–12.5%), N2006/ K = 27.4% (PI = 18.3%–39.5%), N2020/K = 61.8% (PI = 23.8%–88.6%), and N2040/K = 97.3% (PI= 31.6%–99.9%). Despite apparent recovery in the past three decades, the western South Atlantic humpback whale population is still low relative to its pre-exploitation size and requires continued conservation efforts. 
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Ward, E.*, A.N. Zerbini, P.G. Kinas, M.H. Engel, and A. Andriolo. 2011. Estimates of population growth rates of humpback whales (Megaptera novaeangliae) in the wintering grounds along the coast of Brazil (Breeding Stock A). Journal of Cetacean Research and Management (Special Issue 3):145-149.
 
*Contact e-mail: warde at u.washington.edu
 
Humpback whales wintering off the eastern coast of Brazil were heavily exploited by commercial whaling in the Southern Hemisphere. During recent years, clear signs of recovery have been observed, but few estimates of population growth rate exist. In this study, quantitative estimates of rates of population increase are obtained from sighting per unit of effort data (1995–98) using generalized linear models and maximum likelihood estimation. The error distributions considered for the models were Poisson and negative binomial. Predictors of the number of sightings included the year, month and 2-week periods during which the sightings were made. Predictors were treated as factors or numeric variables. For the numeric variables, quadratic dependence was also considered for each predictor to allow for possible non linear relationships. Using Akaike Information Criterion (AICc) as a model selection criterion, the best model included year and month as continuous predictors. The data indicated strong support for the negative binomial over the Poisson models, but did not support models based on a finer temporal scale than month. Assuming year to be a linear predictor, the best estimate of the growth rate for the population wintering off Brazil was 7.4% per year (95% CI = 0.6–14.5%) during the period 1995– 98. This estimate provides additional quantitative evidence that this population has been increasing and is consistent with the observed growth rates of other humpback whale stocks. 
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Strindberg, S.*, P.J. Ersts, T. Collins, G-P Sounguet, and H.C. Rosenbaum. 2011. Line transect distance sampling estimates of humpback whale abundance and distribution on their wintering grounds in the coastal waters of Gabon. Journal of Cetacean Research and Management (Special Issue 3):153-160.
 
*Contact e-mail: sstrindberg at wcs.org
 
There have been few recent estimates of abundance for humpback whales (Megaptera novaeangliae) in the eastern South Atlantic Ocean. The first distance sampling survey of the coastal waters of Gabon was conducted in 2002. The difficult logistics of covering a large survey region with limited time, effort and refuelling opportunities required a line transect survey design that carefully balanced the theoretical demands of distance sampling with these constraints. Inshore/offshore zigzag transects were conducted to a distance of up to approximately 50 n.miles from the coast of Gabon corresponding to the 1,000m depth contour, from the border with Equatorial Guinea to a point south of Mayumba, near the Congo border representing 1,488 n.miles of survey effort. Seventy-nine different groups of humpback whales were observed throughout the survey area comprising a northern (Equatorial Guinea to Cap Lopez) and southern (Cap Lopez to Gamba) survey stratum. Relatively large numbers of whales were encountered throughout the southern stratum; encounter rates and densities were considerably lower in the northern stratum. The initial abundance estimate from a distance sampling analysis suggests that more than 1,200 humpback whales were present in Gabon’s coastal waters during the survey period. This estimate does not account for either availability or perception bias. In addition, this instantaneous snapshot of the number of whales occupying Gabon’s coastal waters is likely to correspond to only a portion of the population that uses these waters over time. However, the abundance estimate derived from the aerial survey are consistent with those based on photographic and genetic capture-recapture techniques. A continuing research programme in this area will help refine estimates of humpback whale abundance and using genetic and photographic data also establish the relationships between this and other populations. This is important given the potential overlap of humpback whales in large numbers throughout this region and the current extent and continued expansion of hydrocarbon exploration and extraction activities throughout the Gulf of Guinea. 
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Findlay, K.*, M. Meÿer, S. Elwen, D. Kotze, R. Johnson, P. Truter, C. Uamusse, S. Sitoe, C. Wilke, S. Kerwath, S. Swanson, L. Staverees, and J. van der Westhuizen. 2011. Distribution and abundance of humpback whales, Megaptera novaeangliae, off the coast of Mozambique, 2003. Journal of Cetacean Research and Management (Special Issue 3):163-174.
 
*Contact e-mail: kenfin at mweb.co.za
 
Humpback whales within the southwestern Indian Ocean undertake annual migrations from summer Antarctic/Southern Ocean feeding grounds to winter breeding grounds in the tropical and sub-tropical coastal waters of Mozambique, Madagascar and the central Mozambique Channel Islands. Little is known of the inter-relationship of humpback whales on each of these wintering grounds, or the inter-relationship of these wintering grounds with the summer Antarctic feeding grounds. A line-transect survey of cetacean species was carried out in Mozambique coastal waters between Cabo Inhaca (26°00’S, 33°05’E) and just north of Mozambique Island (14°26’S, 40°53’E) and between the 20 and 200m isobaths, over the period 26 August to 7 September 2003. The majority (98.1%) of 951.8 n.miles of search effort carried out on this survey was in passing mode due to the high densities of whales encountered. Humpback whales were the only large whales to be identified and the distribution of 691 sightings of an estimated 1,130 individual
humpback whales and 132 sightings of an estimated 154 large unidentified whales show distribution throughout the survey region. Two sightings of individual small whales were made in the region of Inhambane. In general, higher than expected sighting densities (based on survey effort) were recorded in the region between Cabo Inhaca and Xai-Xai, and in the region of the Pantaloon and David Shoals to the north east of Quelimane. Lower than expected sighting densities were recorded over the Sofala Banks. No distribution trends could be ascribed to environmental parameters, apart from whales being distributed in waters of higher salinities than expected, possibly due to turbidity associated with low salinity water arising from river input. Groups containing a cow and calf pair were distributed across the entire region surveyed. Analyses of unstratified data result in a total abundance estimate of 6,808 (CV = 0.14)
humpback and unidentified whales in the 14,029.5 n.mile2 area surveyed. As a result of the differences in width of the coastal shelf area along the coast of Mozambique, the line transect survey data were further analysed in four strata. Pooling of estimates over these four strata results in a total abundance of 6,664 whales (CV = 0.16), with highest densities in the southernmost stratum and the lowest densities in the narrow shelf region across the Sofala Banks. Similar analyses of humpback whales only resulted in abundance estimates of 5,930 (CV = 0.15) (unstratified data) and 5,965 whales (CV = 0.17) (data analysed by four strata). Although not directly comparable due to differing survey platforms, these estimates indicate the population to have increased since previous surveys in the early 1990s. 
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Ersts, P.J., J. Kiszka, M. Vély, and H.C. Rosenbaum. 2011. Density, group composition, and encounter rates of humpback whales (Megaptera novaeangliae) in the eastern Comoros Archipelago (C2). Journal of Cetacean Research and Management (Special Issue 3):175-182.
 
*Contact e-mail: ersts at amnh.org
 
The Comoros Archipelago is an assemblage of oceanic islands, banks and offshore reef systems that longitudinally span the northern Mozambique Channel. The greater Comoros Archipelago has been designated by the IWC as Wintering sub-Region C2 for humpback whales and is currently considered data deficient. Since 1997, annual marine mammal surveys of varying length and objective have been carried out in the waters surrounding Mayotte, the eastern most island in the Comoros Archipelago. The humpback whales component of these surveys focused effort in and around the lagoon surrounding Mayotte. While it is expected that humpback whales can found throughout Comoros Archipelago it still remains unknown as to what degree humpback whales utilise specific banks and offshore reef systems within this area. Surveys conducted in 2002 and 2003 included passing mode and closing mode components intended to examine the density, group composition and encounter rates of humpback whales in an offshore reef complex and a bank adjacent to the lagoon surround Mayotte. The densities of humpback whales, out to one nautical mile from the surveyed transects, ranged from 0.027 to 0.618 whales/n.mile2 across three study sites. Females with calves were the most frequently encountered group type. Encounter rates ranged from 0.98 to 2.36 groups per hour of search effort. These results, while exploratory in nature, indicate that the eastern region of the Comoros may be an important area for humpback whales during the late austral winter months and that additional, more intensive systematic research is warranted.
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Minton, G., T. Collins, K. Findlay, P.J. Ersts, H. Rosenbaum, P. Berggren, and R. Baldwin. 2011. Seasonal distribution, abundance, habitat use and population identity of humpback whales in Oman Journal of Cetacean Research and Management (Special Issue 3):185-198.
 
*Contact e-mail: gianna.minton at gmail.com
 
Previously published data on the occurrence of humpback whales (Megaptera novaeangliae) in the Arabian Sea suggests that the region hosts a non-migratory population that adheres to a Northern Hemisphere breeding cycle. In order to investigate the distribution and abundance of this population, twelve small boat surveys were conducted in three main locations off the coast of Oman between February 2000 and November 2004. Humpback whales were observed during surveys in Dhofar and Gulf of Masirah on Oman’s Arabian Sea coast, but not during surveys in the Muscat region in the Gulf of Oman. An even ratio of males to females was observed and sampled during surveys in the Gulf of Masirah, which was surveyed in October and November (n = 38), while almost all whales sampled in Dhofar in February/March were male (n = 28). Song was detected frequently in the bay surrounding the Halaniyat Islands (formerly known as the Kuria Muria Bay) in February/March, but observations of mother-calf pairs were sparse, and competitive groups were absent. Feeding was observed in both October/November and February/March, but behavioural and environmental observations indicate that the Gulf of Masirah is primarily an important feeding ground, while the Dhofar region, particularly the Halaniyat Bay, may be a breeding area. However, limited survey effort and a lack of recent observations of mother-calf pairs or competitive groups raises the possibility that the primary mating, calving and nursing areas are yet to be identified. Sixty-four individual whales were identified using photographs of dorsal fins or tail flukes. A high rate of re-sightings between years and between survey areas at different times of the year indicates year-round residence off the coast of Oman. A Chapman’s modified Petersen estimator was applied to various data pairings to calculate abundance. All pairings yielded estimates of less than 100 individuals, but sample sizes were small and there were various sources of possible bias. Analysis of scarring on the caudal peduncle region of identified individuals in Oman indicates that between 30 and 40% are likely to have been involved in entanglements with fishing gear. Comparison of the Oman photo-identification catalogue with those from Zanzibar, Antongil Bay (Madagascar) and Mayotte and the Geyser Atoll (Comoros Archipelago), yielded no photographic matches. These data are consistent with the hypothesis of a discrete population. The distribution of fluke pigmentation rankings from the Oman catalogue, which varied significantly from those of Madagascar and Mayotte, provides further evidence for this theory. The evidence presented here provides a strong underpinning for the recent IUCN Red List classification of the Arabian Sea sub-population of humpback whales as Endangered. In light of ongoing coastal development and other threats to this population’s habitat and future survival, urgent research and conservation measures are recommended. 
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Brandão, A., and D.S. Butterworth. 2011. Concerning demographic limitations on the population growth rate of west Australian (Breeding Stock D) humpback whales. Journal of Cetacean Research and Management (Special Issue 3):201-208.
 
*Contact e-mail: anabela.brandao at uct.ac.za
 
The upper bound of 0.126 on the maximum demographically possible annual growth rate for humpback whales that has standardly been imposed on recent applications of age-aggregated assessment models for this species in the IWC Scientific Committee, is based on an analysis that assumes steady age structure. It is conceivable that transient age-structure effects could admit greater population growth rates for short periods than suggested by such a bound. This possibility is addressed by developing an age-structured population model in which possible density dependent changes in pregnancy rate, age at first parturition and natural mortality are modeled explicitly, and allowance is made for the possibility of natural mortality increasing at older ages. The model is applied to the case of the west Australian humpback whale population (Breeding Stock D), for which breeding ground surveys over the 1982–1994 period provide a point estimate of 0.10 for the annual population growth rate. Results based upon the breeding population survey estimate of abundance of 10,032 in 1999 suggest that 0.12 is the maximum demographically feasible annual rate of increase for this stock over 1982–1994 if it is a closed population. This result is based on essentially the same parameter choices as led to the earlier r = 0.126 bound, i.e. that in the limit of low population size the age at first parturition approaches five years from above, the annual pregnancy rate 0.5 from below, and the annual natural mortality rate 0.01 from above. Transient effects do not appear able to reconcile the observed rate of increase with less extreme values of demographic parameters than led to the previously imposed upper bound of 0.126 on the maximum possible annual growth rate. Although use of extreme values reported for demographic parameters for Northern Hemisphere humpback whale populations, rather than those considered here, would reduce this suggested maximum rate of 0.12, the conclusion that transient effects have a very limited impact on observed population growth rates would be unlikely to change.
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Hedley, S.L.*, J.L. Bannister, and R.A. Dunlop. 2011. Abundance estimates of Southern Hemisphere Breeding Stock ‘D’ humpback whales from aerial and land-based surveys off Shark Bay, Western Australia, 2008. Journal of Cetacean Research and Management (Special Issue 3):209-221.
 
*Contact e-mail: sharon at countingwhales.co.uk
 
Single platform aerial line transect and land-based surveys of Southern Hemisphere Breeding Stock ‘D’ humpback whales Megaptera novaeangliae were undertaken off Shark Bay, Western Australia to provide absolute abundance estimates of animals migrating northward along the western Australian coast. The aerial survey flew a total of 28 flights, of which 26 were completed successfully, from 24 June–19 August 2008. The land-based survey was undertaken from Cape Inscription, Dirk Hartog Island, Shark Bay, during the expected peak of the whales’ northward migration, from 8–20 July. During the first week of the land-based survey, some double count effort was undertaken to provide information on the numbers of pods missed from the land station. The assumed period of northward migration was 2 June–7 September. Estimated abundance of northward-migrating whales during that time is 34,290 (95% CI: (27,340–53,350)), representing an annual rate of increase of 12.9% (CV = 0.20) since an estimate of 11,500 in 1999. This estimate is based on an estimate of relative abundance of surface-available whales of 10,840 (8,640–16,860), and an estimated g(0) of 0.32. There were considerable practical difficulties encountered during the land-based survey which reduced the effectiveness of the dual-survey approach for estimating g(0) for the aerial survey. Furthermore only about 15% of whales were estimated to be within the visual range of the land-based station. Alternative approaches for estimating g(0) from these data are therefore also presented, resulting in considerably higher estimates of around 0.6–0.7, and yielding a conservative abundance estimate of 17,810 (14,210–27,720).
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Paxton, C.G.M.*, S.L. Hedley, and J.L. Bannister. 2011. Group IV humpback whales: their status from aerial and land-based surveys off Western Australia, 2005 Journal of Cetacean Research and Management (Special Issue 3):223-234.
 
*Contact e-mail: cgp2 at st-andrews.ac.uk
 
Single platform aerial line transect and land-based surveys of Southern Hemisphere Group IV humpback whales were undertaken to provide absolute abundance estimates of animals migrating northward along the western Australian coast during June–August 2005. The aerial survey was designed to cover the whole period of northward migration but the resulting estimates from that survey alone could only, at best, provide relative abundance estimates as it was not possible to estimate g(0), the detection probability along the trackline, from the data. Owing to logistical constraints, the land-based survey was only possible for a much shorter period (two weeks during the expected peak of the migration in mid-July). This paper proposes three methods that utilise these complementary data in different ways to attempt to obtain absolute abundance estimates. The aerial line transect data were used to estimate relative whale density (for each day), allowing absolute abundance from the land-based survey to be estimated for the short period of its duration. In turn, the land-based survey allowed estimation of g(0) for the aerial survey. Absolute estimates of abundance for the aerial survey were obtained by combining the g(0) estimate with the relative density estimates, summing over the appropriate number of days. The most reliable estimate of northward migrating whales passing the land station for the period of the land-based survey only was 4,700 (95% CI 2,700–14,000). The most reliable estimate for the number of whales passing through the aerial survey region for the duration of that survey (55 days from June through to August) was 10,300 (95% CI 6,700–24,500). This is a conservative estimate because the duration of the aerial survey was almost certainly shorter than the period of the migration. Extrapolation beyond the end of this survey was considered unreliable, but abundance from the estimated start of the migration to the end of the survey (87 days from mid April to August) was estimated to be 12,800 (95% CI 7,500–44,600). The estimated number of whales depends crucially on the assumed migration and period of migration. Results for different migration parameters are also presented. The point estimates of abundance, whilst higher than those from a previous survey in 1999 (when adjusted for survey duration) are not significantly so. The peak of the whales’ distribution was found at c.90m water depth. 
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Forestell, P.*, G.D. Kaufman, and M. Chaloupka. 2011. Long term trends in abundance of humpback whales in Hervey Bay, Australia. Journal of Cetacean Research and Management (Special Issue 3):237-241.
 
*Contact e-mail: paul.forestell at liu.edu
 
Seasonal abundance estimates of humpback whales resident during the austral winter in Hervey Bay, Queensland, Australia between 1987 and 2007 were obtained from a capture-mark-recapture study using photo-identification images of 3,155 individual whales. Hervey Bay is a major southbound stopover site for Breeding Stock E humpback whales returning to Antarctic waters from overwintering in the vicinity of the Great Barrier Reef. Annual survival, recapture and abundance estimates were derived using a Cormack-Jolly-Seber modelling approach and a Horwitz-Thompson type abundance estimator. The best-fit model was a 2-ageclass Brownie-Robson type model that estimated apparent annual survival for the non-transient winter stopover ageclass at approximately 0.945 (95% confidence interval: 0.929–0.957). Apparent annual abundance of winter stopover humpback whales in Hervey Bay was estimated to
have increased significantly over the past 21 years at ca. 13.4% per annum (95% CI 11.6–15.2). The most recent Hervey Bay winter stopover population (2007) was estimated to comprise ca. 6,246 post-yearlings (95% CI 5,011–7,482). This estimated rate of population increase is similar to estimates for other surveys along the east Australian coast but significantly higher than the intrinsic rate of increase (rmax) estimated recently for several recovering Southern Hemisphere humpback whale stocks based on the feeding ground sampling. 
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Noad, M.J., R.A. Dunlop, D. Paton, and D.H. Cato. 2011. Absolute and relative abundance estimates of Australian east coast humpback whales (Megaptera novaeangliae). Journal of Cetacean Research and Management (Special Issue 3):243-252.
 
*no contact e-mail information provided
 
The humpback whales that migrate along the east coast of Australia were hunted to near-extinction in the 1950s and early 1960s. Two independent series of land-based surveys conducted over the last 25 years during the whales’ northward migration along the Australian coastline have demonstrated a rapid increase in the size of the population. In 2004 we conducted a survey of the migratory population as a continuation of these series of surveys. Two methods of data analysis were used in line with the previous surveys, both for calculation of absolute and relative abundance. We consider the best estimates for 2004 to be 7,090±660 (95% CI) whales with an annual rate of increase of 10.6±0.5% (95% CI) for 1987–2004. The rate of increase agrees with those previously obtained for this population and demonstrates the continuation of a strong post-exploitation recovery. While there are still some uncertainties concerning the absolute abundance estimate and structure of this population, the rate of annual increase should be independent of these and highly robust. 
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Paton, D.A., L. Brooks, D. Burns, T. Franklin, W. Franklin, P. Harrison, and P. Baverstock. 2011. Abundance of east coast Australian humpback whales (Megaptera novaeangliae) in 2005 estimated using multi-point sampling and capture-recapture analysis. Journal of Cetacean Research and Management (Special Issue 3):253-259.
 
*Contact e-mail: dave at blueplanetmarine.com
 
The humpback whales (Megaptera novaeangliae) that migrate along the east coast of Australia were hunted to near extinction during the last century. This remnant population is part of Breeding Stock E. Previous abundance estimates for the east Australian portion of Breeding Stock E have been based mainly on land-based counts. Here we present a capture-recapture abundance estimate for this population using photo-identification data. These data were collected at three locations on the migration route (Byron Bay – northern migration, Hervey Bay and Ballina – southern migration) in order to estimate the population of humpback whales that migrated along the east coast of Australia in 2005. The capture-recapture data were analysed using a variety of closed population models with a model-averaged estimate of 7,041 (95% CI 4,075–10,008) whales. 
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Paton, D.A.*, and E. Kniest. 2011. Population growth of Australian East Coast humpback whales, observed from Cape Byron, 1998 to 2004. Journal of Cetacean Research and Management (Special Issue 3):261-268.
 
*Contact e-mail: dave at blueplanetmarine.com
 
Humpback whales (Megaptera novaeangliae) that migrate past the east coast of Australia comprise part of Group V (E(i) breeding stock). From 1995 to 2004 an annual 16 day survey was conducted from Cape Byron (28°37’S, 153°38’E), the most easterly point on the Australian mainland, monitoring the peak of the humpback whale northern migration. The annual rate of increase between 1998 and 2004 of humpback whales observed off Cape Byron is 11.0% (95% CI 2.3–20.5%). This rate of increase is consistent with that recorded from other studies of the humpback whale population off the east coast of Australia. The large confidence intervals associated with this estimate are due to considerable inter-annual variation in counts. The most likely explanation for this being the short survey period, which may not have always coincided with the peak of migration, and in some years a large proportion of whales passed Cape Byron at a greater distance out to sea, making sightability more difficult. 
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Garrigue, C.*, T. Franklin, R. Constantine, K. Russell, D. Burns, M. Poole, D. Paton, N. Hauser, M. Oremus, S. Childerhouse, D. Mattila, N. Gibbs, W. Franklin, J. Robbins, P. Clapham, and C.S. Baker. 2011. First assessment of interchange of humpback whales between Oceania and the east coast of Australia. Journal of Cetacean Research and Management (Special Issue 3):269-274.
 
*Contact e-mail: op.cetaces at lagoon.nc
 
The interchange of individual humpback whales between the wintering grounds of Oceania (South Pacific) and the east coast of Australia were documented by individual identification photographs collected from 1999 to 2004. Interchange was assessed using regional catalogues of fluke photographs, totalling 672 individuals from Oceania (represented by New Zealand, New Caledonia, Vanuatu, Fiji, Samoa, Tonga, Niue, Cook Island, French Polynesia and American Samoa) and 1,242 individuals from Hervey Bay and Byron Bay representing the southbound and the northbound migration along the east coast of Australia (EA). Overall, there were seven documented movements between EA and Oceania. Four instances of movement of four individuals were documented between EA and the closest breeding grounds of New Caledonia. A further three movements were recorded between EA and a small catalogue (n = 13) from the New Zealand migratory corridor. In contrast, during this same period, 20 cases of interchange were documented among nine breeding grounds: French Polynesia, Cook Islands, Niue, American Samoa, Samoa, Tonga, Fiji, Vanuatu and New Caledonia. The low level of interchange between Oceania and the east coast of Australia has important implications for understanding the stock structure and abundance of humpback whales in the South Pacific. 
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Garrigue, C.*, R. Constantine, M. Poole, N Hauser, P. Clapham, M. Donoghue, K.  Russell, D. Paton, D.K. Mattila, J.  Robbins, and C.S. Baker. 2011. Movement of individual humpback whales between wintering grounds of Oceania (South Pacific), 1999 to 2004. Journal of Cetacean Research and Management (Special Issue 3):275-281.
 
*Contact e-mail: op.cetaces at lagoon.nc
 
The movement of individual humpback whales between regional breeding grounds of Oceania (South Pacific) was documented by individual identification photographs collected from 1999 to 2004. Photographs were collected with comparable effort across the six years in four primary island breeding grounds: New Caledonia, Tonga (Vava’u) the Cook Islands and French Polynesia (Mo’orea and Rurutu); with smaller effort in adjacent regions: Vanuatu, Fiji, Samoa, Niue and American Samoa. Interchange among wintering grounds was assessed first with all usable photographs included in each regional catalogue, representing 1,080 regional sightings (including within-region and between-region resightings) of 949 individual whales from Oceania. From this, 28 cases of movement between (mostly adjacent) regions were documented. Previously undocumented interchange was found between regions of central Oceania and the western South Pacific. No individual was sighted in more than two regions during this six-year period. The documented movement between regions was one-directional, except for one individual sighted first in French Polynesia, then in American Samoa and then back in French Polynesia (each in different years). Only one whale was resighted in more than one region during the same winter season. No directional trend was apparent and movement between regions did not seem to be sex specific. A systematic quality control review of all catalogues was then implemented to calculate standardised indices of within-region return and between-region interchange, resulting in a quality controlled catalogue of 776 regional sightings of 659 individuals. The standardized indices confirmed that the probability of between-region interchange was low, relative to within-region return, supporting the assumption of multiple management units or stocks in Oceania. The relative isolation of breeding regions and the movement of individuals across the longitudinal borders of Antarctic management Areas V and VI has important implications for the allocation of historical catches from the Antarctic and therefore, for assessing current levels of recovery for breeding stocks. 
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Félix, F.*, M. Muñoz, J. Falconi, N. Botero, and B. Haase. 2011. Entanglement of humpback whales in artisanal fishing gear in Ecuador. Journal of Cetacean Research and Management (Special Issue 3):285-290.
 
*Contact e-mail: fefelix90 at hotmail.com
 
Southeastern Pacific humpback whales (Breeding Stock G) congregate along the northwest coast of South America during the austral winter (July–October). Information collected from stranded animals for more than a decade in Ecuador and Colombia indicates that entanglement in fishing gear is a major threat for this population during the breeding season. Twelve new cases are reported here of live individual whales entangled in artisanal gillnets on the central coast of Ecuador from 2004 to 2007. The varying severity of the entanglement and the behaviour of the animals involved indicated that they had differing chances of survival. The findings confirm that the problem persists, although the impact on the population is unknown. The necessity of taking conservation measures to reduce the current level of entanglement is reiterated. Creation and training of rescue teams seems an appropriate alternative in the short-term, but in the long-term it will be necessary to design and implement actions with a wider regional scope, since the problem extends also to at least other two neighbouring countries. 
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Félix, F.*, D.M. Palacios, S.K. Salazar, S. Caballero, B. Haase, and J. Falconi. 2011. The 2005 Galápagos humpback whale expedition: A first attempt to assess and characterise the population in the Archipelago. Journal of Cetacean Research and Management (Special Issue 3):291-300.
 
*Contact e-mail: fefelix90 at hotmail.com
 
It has been known for some time that humpback whales (Megaptera novaeangliae) occur in waters of the Galápagos Islands, an oceanic archipelago located 1,000km west of Ecuador, South America (1°S, 91°W), but their presence there has been poorly documented. Although presumed, no linkage has been established between Galápagos and southeast Pacific humpback whales (Breeding Stock G), the nearest breeding stock. An expedition to Galápagos was carried out between 31 August and 10 September 2005 to document the presence of humpback whales, their distribution, and their relationship to other stocks in the Pacific. Surveys covered 722km of the central and southern parts of the archipelago. Only one adult with a newborn calf was found at Santa Fé Island (0°47’S, 90°05.1’W), yielding an encounter rate of 0.27 whales per 100km of survey. A hydrophone with a response frequency range of 0.25–25kHz was dropped 25 times, but no whale sounds were heard. A skin sample was obtained by darting of the adult at Santa Fé, and was used for genetic analysis of the mtDNA control region. The haplotype of the Galápagos specimen has been found in a few individuals sampled previously off Colombia, Ecuador and the Antarctic Peninsula, thus establishing at least some degree of relatedness with Breeding Stock G. The observations, combined with a compilation of historical and recent sighting information in the archipelago, support the idea that Galápagos is a breeding area for the species. Further studies are needed to establish the level of discreteness, size and other basic aspects of the Galápagos humpback whale population. 
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Félix, F.*, C. Castro, J.L.  Laake, B. Haase, and M. Scheidat. 2011. Abundance and survival estimates of the southeastern Pacific humpback whale stock from 1991-2006 photo-identification surveys in Ecuador. Journal of Cetacean Research and Management (Special Issue 3): 301-307.
 
*Contact e-mail: fefelix90 at hotmail.com
 
Southeastern Pacific humpback whales (Breeding Stock G) breed along the northwestern coast of South America and farther north up to Costa Rica. Photo-identification surveys conducted aboard whalewatching vessels during the migration/breeding season from June to September between 1991 and 2006 off the coast of Ecuador (2°S, 81°W) have produced a database of 1,511 individual whales. Comparisons of photographs produced 190 between-year re-sightings of 155 individual whales. Closed and open capture-recapture models were used to estimate abundance and survival. The best estimate of abundance in 2006 with the Chapman modified-Petersen was 6,504 (95% CI: 4,270–9,907; CV = 0.21). Abundance estimates from open population models were considerably lower due to heterogeneity in capture probability which produced a ‘transient’ effect. Our best estimate of true survival was 0.919 (95% CI: 0.850–0.958). Heterogeneity most likely occurred from inter-annual variation in sampling and unknown structure and variation in the migration timing and corridor. A more extensive collaborative effort including other wintering areas further north as well as integrating breeding-feeding data will help to reduce heterogeneity and increase precision in abundance and survival estimates. 
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Johnston, S.J.*, A.N. Zerbini, and D.S. Butterworth. 2011. A Bayesian approach to assess the status of Southern Hemisphere humpback whales (Megaptera novaeangliae) with an application to Breeding Stock G. Journal of Cetacean Research and Management (Special issue 3):309-318.
 
*Contact e-mail: Susan.Holloway at uct.ac.za
 
The Bayesian stock assessment methodology presently being applied in the Comprehensive Assessment of the Southern Hemisphere humpback whales, which uses a sex- and age-aggregated population model, is detailed. This methodology is applied to Breeding Stock G, which winters off the west coast of South America. This application takes into account the recently updated historic catch series, as well as the most recent estimates of absolute abundance and population trend information. 
  
 		 	   		  
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