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Embracing conservation success of recovering humpback whale populations: Evaluating the case for downlisting their conservation status in Australia

Authors:
Embracing conservation success of recovering humpback whale
populations: Evaluating the case for downlisting their conservation
status in Australia
Michelle Bejder
a
, David W. Johnston
b,c
, Joshua Smith
c
, Ari Friedlaender
d
, Lars Bejder
b,c,
n
a
BMT Oceanica, PO Box 462, Wembley, Western Australia 6913, Australia
b
Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University Marine Laboratory,135 Duke Marine Lab Road, Beaufort,
NC 28516, USA
c
Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia
d
Marine Mammal Institute, Hateld Marine Science Center, Oregon State University, 2030 SE, Marine Science Drive, Newport, OR 97365, USA
article info
Article history:
Received 16 February 2015
Received in revised form
18 May 2015
Accepted 18 May 2015
Keywords:
Humpback whale
Recovery
Conservation status
Downlisting
Australia
abstract
Optimism and hope in conservation biology are supported by examples of endangered species recovery,
such as the population growth observed in humpback whales in several of the world's oceans. In
Australia, monitoring data suggest rapid recovery for both east and west coast populations, which are
now larger than 50% of their pre-whaling abundance. The measured growth rates exceed known species
trends worldwide and have no indication of diminishing. Under Australian Commonwealth legislation
and regulations, these populations should be considered for downlisting, as they are not eligible for
listing as a threatened species against all statutory criteria. A change in conservation status will produce
new challenges for the conservation and management of a recovered species, especially with the
Australian economic landscape experiencing large-scale growth and development in recent years. More
importantly, a recovered humpback whale population may bring a positive shift in the research goals
and objectives throughout Australia by ensuring other endangered species an equal chance of recovery
while delivering hope, optimism, and an opportunity to celebrate a conservation success.
&2015 Elsevier Ltd. All rights reserved.
1. Introduction
Marine mammals exhibit many of the characteristics of Ehren-
feld's [1] hypothetical most endangered animal, including large
size, long lifespans, late reproductive age, few offspring, commer-
cial value, distributions that cross international boundaries, and
behaviors that place them at risk from a number of anthropogenic
activities [2,3]. These vulnerabilities manifested in historic extinc-
tions (e.g. Steller's sea cow (Hydrodamalis gigas)[4]), modern
extinctions (e.g. Yangtze river dolphin or baiji (Lipotes vexillifer)
[57]), and the plight of critically endangered species that may go
extinct within a generation (e.g. vaquita (Phocoena sinus); [810]).
Despite the vulnerability of marine mammals to negative human
impacts (intentional or otherwise), there is room for optimism.
Optimism and hope in conservation biology will always be
important factors for species recovery and success [1114] . While
some debate the semantic differences between hope and opti-
mism [12], we purposely conate the two, as one can lead to the
other regardless of initial state. Optimism and hope in conserva-
tion biology are essential, as the relentless communication of
conservation problems does not always encourage politicians,
policy makers, and the public to solve them [15]. The plight of
many marine mammal populations remains of concern globally,
and conservation biologists should not detract from these cases.
However, opportunities to illustrate and promote success must
also be highlighted, thus providing hope and optimism that
ongoing conservation actions can prevail. Ultimately, conservation
biologists seek to juxtapose the long litany of sobering conserva-
tion concerns with inspirational examples that motivate people to
use resources wisely and take sustainable and effective actions.
Presented here is an argument to revise the conservation status
of the population of humpback whales (Megaptera novaeangilae)
that inhabit Australian waters under the Environment Protection
and Biodiversity Conservation Act 1999 (EPBC Act), thus providing a
sensible and suitable opportunity to celebrate the recovery of an
iconic species, without dismantling existing legislative protections
from new and existing threats. Downlisting their conservation
Contents lists available at ScienceDirect
journal homepage: www.elsevier.com/locate/marpol
Marine Policy
http://dx.doi.org/10.1016/j.marpol.2015.05.007
0308-597X/&2015 Elsevier Ltd. All rights reserved.
n
Corresponding author.
E-mail addresses: michelle.bejder@gmail.com (M. Bejder),
david.johnston@duke.edu (D.W. Johnston), j.smith@murdoch.edu.au (J. Smith),
Ari.friedlaender@oregonstate.edu (A. Friedlaender),
l.bejder@murdoch.edu.au (L. Bejder).
Please cite this article as: Bejder M, et al. Embracing conservation success of recovering humpback whale populations: Evaluating the
case for downlisting their conservation status in Australia. Mar. Policy (2015), http://dx.doi.org/10.1016/j.marpol.2015.05.007i
Marine Policy (∎∎∎∎)∎∎∎∎∎∎
status is consistent with recent decisions made internationally by
government agencies and conservation organizations to re-assess
the status of other humpback whale populations worldwide.
Furthermore, under the current management rationale, the Aus-
tralian humpback whale populations would unquestionably sur-
pass the justication to warrant downlisting. Taken collectively,
these decisions provide evidence of successful marine mammal
conservation that will encourage and justify future management
actions, and the allocation of future funding to species and
ecosystems at greater risk of extinction.
2. International context
The International Union for Conservation of Nature (IUCN)
downlisted the global status of humpback whales from a Red List
Category of Vulnerable to Least Concern. This decision was based
on trends in data and the likelihood that current abundance
estimates (460,000 whales worldwide) are greater than 50% of
the species' abundance in 1940 [16]. However, the IUCN acknowl-
edge a global concern for discrete and smaller sub-populations of
humpback whales from the Arabian Sea, western North Pacic,
west coast of Africa, and South Pacic subpopulations in portions
of Oceania [16]. While these smaller populations remain data
decient and potential threats to recovery still exist, the IUCN
determined that the humpback whale global status is not sig-
nicantly impacted by current levels of anthropogenic mortality,
but rather is recovering strongly.
Humpback whale recovery has also led to downlisting in other
regions. In April 2014, the Canadian government reclassied the
North Pacic population of humpback whales in British Columbia
from threatened to species of special concern [17]. Based on an annual
rate of increase of 4.96.8% [18] with no signs of declining, this
population was determined to be recovering, despite the current
population estimate (2145 whales) being less than pre-exploitation
abundance (4000 whales) in 1905. In the USA, humpback whales
are listed as Endangered under the Endangered Species Act and
Depleted under the U.S. Marine Mammal Protection Act [19].Based
on 20042006 data, the best available abundance estimate for the
entire North Pacic region included 20,800 humpback whales [19].
While still considered to be an under-estimate of actual abundance,
the estimate exceeds pre-exploitation population values of 15,000
humpback whales throughout the North Pacic[20].In2010,theUSA
National Marine Fisheries Service (NMFS) initiated a global humpback
whale status review to ensure that the species conservation listing is
accurate and based on the best scientic and commercial data
available [21],andanal report was published in March 2015 [22].
Based on distribution, ecological situation, genetics, and other factors,
15 humpback whale distinct population segments worldwide were
identied, among which nine were determined to not be at risk of
extinction with high certainty: the West Indies, Hawaii, Mexico, west
Australia, east Australia, Colombia, Brazil, Gabon/Southwest Africa,
and Southeast Africa/Madagascar [22].Consequently,in2013and
2014, petitions requested that NMFS reclassify and remove two of the
three North Pacic humpback whale populations from the List of
Endangered and Threatened Species. NMFS responded with a positive
nding that the petitions warranted action [23].
3. Exploitation and recovery of Australian humpback whales
The International Whaling Commission (IWC) recognizes seven
major breeding populations of humpback whales in the Southern
Hemisphere [24], of which two (D and E1) have their primary
calving areas in waters off north-western and north-eastern
Australia, respectively [25,26]. The historical exploitation of these
populations began in the 19th century, with whaling logbook
records of humpback whales sighted and caught along northern
and southern coasts of Western Australia [27]. Modern whaling in
Australian waters began in 1912 [28,29]. Although right and sperm
whales (Eubalaena australis and Physeter macrocephalus, respec-
tively) were the preferred species, humpback whales that calved in
Australian waters were killed at both ends of their geographic
range: on their Antarctic feeding grounds and along their migra-
tory pathways to their breeding grounds. The modernization of
whaling techniques resulted in industrial advancements (e.g.
steam powered boats and explosive harpoons), and catches were
achieved efciently from the Australian, shore-based whaling
stations [28,29]. From 19351939, whaling records listed more
than 12,000 humpback whales taken from Breeding Stock D
(Group IV), with substantially less ( 200 whales) from Breeding
Stock E1 (Group V). The catch levels from 1949 to 1962 reported
higher catch numbers, including greater than 18,000 and 15,000
whales from Breeding Stocks D and E1, respectively [28].
Furthermore, unreported and illegal whaling operations by the
former USSR removed substantial numbers of humpback whales
from the Southern Hemisphere [30]. After the 1961 IWC Antarctic
restrictions, unreported catches of humpback whales from the
Antarctic area were suggested as a likely explanation of high
mortality rates observed [28]. Later revealed in 1993, illegal Soviet
whaling operations continued throughout the Southern Hemi-
sphere until 1972 and caused the greatest decline to humpback
whale populations inhabiting Australian waters, as more than
48,000 whales were taken [3133]. Without whaling competition
and disregarding IWC regulations, the illegal catches dramatically
impacted the already depleted populations from the east coast of
Australia and New Zealand [33].
Despite the devastation caused by whaling, recent monitoring
data suggest a rapid recovery of both Australian humpback whale
populations. Early abundance estimates indicated that Breeding
Stock E1 (Group V) was reduced to approximately 500 humpback
whales by the end of 1962 [28]. However, recent population
assessments incorporated a more comprehensive catch dataset,
including the illegal catches from Soviet Antarctic whaling opera-
tions, and those models presented a likely minimum estimate of
1230 (median) humpback whales in 1968 [34]. Since 1986, annual,
shore-based observations documented population estimates with
consistent rates of increase from 9.7% in 1987 (1100 whales) to
11.7% in 1992 (1896 whales [35,36]). In 2004, land-based surveys
determined that the population recovered to 7090 whales (95% CI
64307750 [37]) and to 9683 whales (95% CI 855610,959) in
2007 [38]. The corresponding long-term rate of increase was
estimated at 10.9% per year. In 2010, the same stock was estimated
at 14,552 whales (95% CI 12,77716,504) with no evidence of a
decline in the growth rate [39].
The lowest population estimate for Breeding Stock D was 268
whales in 1968 [29]. From 1982 to 1994, Bannister [40] estimated
this stock increased to 40005000 whales. In 1999, 2005 and
2008, three surveys were undertaken on this population on their
migratory route near Dirk Hartog Island. These surveys suggested
a 9.7% (CV¼0.25) rate of increase [41]. Unlike the surveys off
eastern Australia, the necessary corrections for availability and
perception bias were difcult to estimate due to challenges in
establishing a suitable land-based observation platform [41].
Therefore, absolute abundance estimates for Breeding Stock D
were difcult to derive and considered to be highly speculative by
the authors [41]. Mindful of the data limitations, Hedley et al. [42]
reported 11,500 whales (95% CI 920014,300) in 2006 and 33,850
whales (95% CI 27,34050,260) in 2008. Similarly in 2008,
Salgado-Kent et al. [43] conducted an aerial survey off the North
West Cape and reported 26,100 whales (95% CI 20,15233,272).
Again, the nal results did not include reliable estimates of
M. Bejder et al. / Marine Policy (∎∎∎∎)∎∎∎∎∎∎2
Please cite this article as: Bejder M, et al. Embracing conservation success of recovering humpback whale populations: Evaluating the
case for downlisting their conservation status in Australia. Mar. Policy (2015), http://dx.doi.org/10.1016/j.marpol.2015.05.007i
availability bias and were also likely to be adversely affected by
north and southbound milling whales overlapping in their migra-
tion paths [44].
Using these and other survey data, the IWC Scientic Commit-
tee continually assesses the recovery of the Australian populations
based on various techniques, such as Bayesian logistic population
dynamic models that require information on life history para-
meters, catch history, feeding, and breeding ground mixing and
distribution, as well as absolute or relative abundance estimates
[34]. These models also assume that the carrying capacity of the
population has not changed since before exploitation [45]. While
the general understanding of some of these parameters and
assumptions remains poorly documented, the modeling process
accommodates uncertainty and includes sensitivity runs to assess
how changes to certain parameters affect the outcome. The results
of the base modelsuggested that the abundance of Breeding
Stock D was 19,200 (17,55324,012; 90% probability interval PI),
while Breeding Stock E1 contained 16,366 whales (14,67418,034;
90% PI). In addition, the model suggested that in 2012, western
and eastern Australian populations were increasing at 9% and 10%
per year, and were 90% (7498; 90% PI) and 63% (5673; 90% PI) of
the pre-whaling population sizes, respectively [46].
Both available survey data and modeling predictions are
limited by the knowledge of certain biological parameters. As
such, maximum rates of increase may never be accurately or
reliably estimated, and the most realistic, theoretical values based
on the best available scientic data may not include maximum
values. Life history parameters will modify as humpback whales
respond to environmental changes, such as reduced exploitation
levels and inter-specic competition. Abundance estimates and
observations collected from breeding areas may present different
birth and mortality rates than those measured from feeding
grounds [47]. While estimating population abundance can be
inherently difcult, it is apparent that both the east and western
Australian populations are recovering rapidly and are now larger
than 50% of their pre-whaling abundance.
Scientic evidence continues to reveal that Australian hump-
back whale populations are increasing at remarkable rates. For the
Southern Hemisphere humpback whales, the IWC set an upper
limit for growth rate at 12.6% [48], very similar to the 12.7% rate of
increase from 2008 [42], which the authors acknowledge to be
biologically implausible but sufciently robust. Thus, the observed
rates of increase for Breeding Stock D meet the IWC maximum
limit. For Breeding Stock E1, the long-term rate of increase (10.9%
from 1984 to 2010 [39]) was under the IWC limit but still
sufciently high. Based on biological parameters of humpback
whales from the Northern Hemisphere, the maximum annual rate
of increase was estimated at 11.8%, with accepted limitations in
demographic parameters, environmental changes and other nat-
ural factors [47].
While some of the documented species trends (e.g. survival
rate, calving rate, age at sexual maturity) from the Northern
Hemisphere populations are not applicable, the Australian hump-
back whale populations' growth near maximum net productivity
was expected for depleted stocks [49,50], providing optimism for
future recovery. Recent population assessment models submitted
to the IWC attempted to clarify the high growth rates observed for
these populations of humpback whales. The results revealed
further uncertainty regarding customary Antarctic stock bound-
aries [50] as well as absolute abundance estimate [51], and
provided initial platforms on which further discussion and analysis
will be developed.
Additionally, it has been proposed that recent shifts in the
species' biological parameters are a possible explanation for
observed rapid population growth, which is reasonable to presume
when exploitation and competition are removed. Currently, the
density-dependent calving interval is accepted as a minimum
possible value of two years and was used to calculate the Breeding
Stock D 12% rate of increase from 1982 to 1994 [52]. If this interval
decreased to one year between calves, a possible 14% rate of
increase would be expected [52]. Therefore, if Breeding Stock D is
in fact experiencing a 12.7% rate of increase [42], it would seem
probable that the calving interval may be reduced and that a
change in the species biological characteristics may be occurring.
Finally, another recent explanation for the recovery of the
Australian humpback whale populations introduced the possibility
that observed rates of increases may be overestimated and
inuenced by immigrations to the breeding grounds in response
to social mating behaviors and natural instincts to aggregate [53].
However, conrming the actual and true biological forces that are
driving the growth of these populations will never be resolved
without more demographic data.
4. Revising the conservation status of humpback whales in
Australia
In Australia, the primary legislation that protects humpback
whales is the EPBC Act, which conserves the biodiversity of the
environment and promotes ecologically sustainable development.
The EPBC Act protects all cetaceans within the Australian Whale
Sanctuary that encompasses all Commonwealth waters, from the
state limit (three nautical miles) to the Australian Exclusive
Economic Zone boundary (200 nautical miles). Killing, injuring
or interfering with a cetacean within the Australian Whale
Sanctuary is a criminal offense and subject to severe penalties.
Currently, humpback whales are a threatened species (vulnerable
status) as well as a migratory species, both of which are identied
by the EPBC Act as a Matter of National Environmental Signicance
(MNES). Any action that is likely to have an environmental impact
on an MNES must be assessed for approval under the EPBC Act.
Thus, any activity within Australian waters that is likely to have an
impact on a humpback whale requires government approval and
permits.
Assessments of the conservation status of native species under
the EPBC Act are made against statutory criteria, which are
established under the EPBC Regulations 2000 [Table 1]. A species
may be considered for removal or downlisting if eligible against all
ve criteria. First, the Australian populations of humpback whales
have undergone substantial abundance reductions during the last
century but are not likely to undergo similar reductions in the
immediate future (Criterion 1). Criterion 2 requires that the
population's geographic distribution is precarious for the survival
of the species, with the extent of occurrence estimated to be less
than 20,000 km
2
or an area of occupancy estimated to be less than
2000 km
2
. The current geographic distributions of Australian
humpback whale populations exceed these limits, is not severely
fragmented, does not exist at limited locations, and is not
observed, inferred or projected to be declining. Extreme uctua-
tions do not exist in terms of occurrence, occupancy, locations,
subpopulations or number of mature individuals of Australian
humpback whales. In reference to an estimate of mature indivi-
duals (Criterion 3), the population's total number is unknown but
presumed to be not limited(o10,000 individuals), and all
scientic evidence to date suggests that these populations are
not in decline but rather recovering strongly. The estimated
number of mature individuals is substantially greater than the
low value for a vulnerable species ( o1000 individuals; Criterion
4). Finally, while quantitative analysis on the probability of
extinction in the wild for the Australian humpback whale popula-
tions has not been published, the available data do not support or
suggest that these populations have a 10% chance of extinction
M. Bejder et al. / Marine Policy (∎∎∎∎)∎∎∎∎∎∎ 3
Please cite this article as: Bejder M, et al. Embracing conservation success of recovering humpback whale populations: Evaluating the
case for downlisting their conservation status in Australia. Mar. Policy (2015), http://dx.doi.org/10.1016/j.marpol.2015.05.007i
within 100 years (Criterion 5). In fact, recent abundance assess-
ments submitted to the IWC (as stated above) demonstrate that
the chance of extinction within 100 years is highly unlikely.
Based on the criteria above [Table 1], available scientic
evidence does not support the listing of humpback whale popula-
tions on the EPBC Act list of Threatened species. However, it is
important to remember that irrespective of the Australian hump-
back whale populations' presence on or absence from the Threa-
tened species list, they are still protected under the EPBC Act as an
MNES based on their qualication as a migratory species.
5. Conclusions
A change in recovery status will inevitably produce new
challenges for species conservation and management. A marine
environment with recovered humpback whale populations will
present new and diverse management challenges and require
alternative approaches to ecological sustainability. The Australian
humpback whales are an exemplary model of recovery, especially
within a marine environment experiencing rapid and concurrent
expansion in industrial and exploration activities. The economic
landscape for Western Australia experienced large-scale growth
and development in recent years, for which environmental assess-
ments and baseline surveys were routinely dedicated to humpback
whales and dugongs [54]. The most probable concerns for future
environmental management will be sustaining the recovery in a
viable marine ecosystem in the midst of human and economic
expansion around Australia and possible shery expansion in the
Southern Ocean, neither of which presents signs of imminent
population decline. An increase in humpback whale interactions
with maritime users is an expected consequence of recovery,
including acoustic disturbance from anthropogenic noise, colli-
sions with vessels, entanglements in shing gear, habitat destruc-
tion from coastal development, and cumulative interactions with
the whale-watch industry.
Scientic data present justiable evidence to support down-
listing the level of legislative protection of humpback whales that
breed in Australian waters. The recovery of Australian humpback
whales demonstrates conservation and management success for a
species that was severely over-exploited. While this success rests
ultimately upon the ongoing moratorium on commercial whaling
and the limited expansion of special permit whaling, the recovery
of humpback whales in Australian waters would not be evident
without the support of conservation science directed at establish-
ing the species' modern range, abundance, and demography. A
recovered humpback whale population could bring a positive shift
in the research goals and objectives throughout Australia. Should
reclassication occur for humpback whales, one of the most
benecial consequences for conservation biology would be to
continue research and management funding to enhance the
survival of other species and ecosystems that are in danger of
extinction and to ensure an equal chance of success as demon-
strated by the humpback whales.
The recovery of the iconic humpback whales of Australia and
elsewhere delivers both hope and optimism, as well as an
opportunity to celebrate success at two levels: (1) the successful
implementation of contentious international management actions
to protect marine species; and (2) the wise and signicant
investment in conservation science, illustrating how human activ-
ity can respond to strong conservation interventions to achieve
outcomes that are not simply for immediate, human material
gains. Worldwide, humpback whale numbers appear to be increas-
ing across a range of populations. While signicant (and often
times seemingly insurmountable) obstacles stand in the face of
conserving many marine species and ecosystems, humpback
whales provide an opportunity to embrace a conservation success.
Acknowledgment
We thank Dr Michael C. Double for his contributions to the
discussion and provision of information.
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Eligibility criteria for removing a species from any category in the list of threatened species under the EPBC Act.
Criterion Description
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Vulnerable (low) o10 0 0
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Endangered (near future)Z20% in 20 years or 5 generations, whichever is longer (100 years max)
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M. Bejder et al. / Marine Policy (∎∎∎∎)∎∎∎∎∎∎ 5
Please cite this article as: Bejder M, et al. Embracing conservation success of recovering humpback whale populations: Evaluating the
case for downlisting their conservation status in Australia. Mar. Policy (2015), http://dx.doi.org/10.1016/j.marpol.2015.05.007i
... The commercial whaling ban of the 20th century has been critical to allow some whale populations to recover in Australian waters including humpback, southern right and pygmy blue whales. 231 However, the southern right whale population in southeast Australia has been slow to recover 232 and still little data exists for cetaceans who rely on offshore areas off the continental shelf including sperm and beaked whales. 233 A major contributor to conservation is the Australian Whale Sanctuary 234 under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) which protects all cetaceans (whales, dolphins and porpoises) in the region. ...
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... When specific threats are removed, target species may recover from being on the brink of extinction. For example: recoveries of marine mammal species following hunting bans (Lowry et al., 2014;Bejder et al., 2016); recovery of native faunas, including invertebrate species, after invasive species eradication on islands (Jones et al., 2016); peregrine falcon, Falco peregrinus Tunstall, 1771, recovery from near-extinction in North America after banning of DDT (Cade & Burnham, 2003). However, these rare successes should not hide the fact that since most species population decreases are caused either multifactorially or by large-scale habitat degradation or loss, removing the cause of the decrease is usually beyond the reach of single conservation actions. ...
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... The 19th and 20th century commercial exploitation of all large cetaceans would therefore have led to massive information network disruption (Schmidt et al., 2010) as populations plummeted to numbers that were between 1% and 10% of historic abundance. However, if large populations of rorqual whales can increase their foraging efficacy by revealing the location of high-quality foraging hotspots to conspecifics, the resulting positive feedback loop may help explain why large whale populations were slow to recover from 19th and 20th century commercial exploitation, but some populations have more recently increased in abundance (Bejder et al., 2016). In contrast, some exploited, particulate-feeding species such as sperm whales, Physeter macrocephalus, have recovered more slowly than expected (Carroll et al., 2014;Gero & Whitehead, 2016). ...
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... In the decades that have followed, large whale populations have undergone varying levels of recovery. Some populations are considered to have reached near to their carrying capacities (e.g., the eastern North Pacific gray whale, Eschrichtius robustus, Punt and Wade, 2012; and both populations of Australian humpback whale, Megaptera novaeangliae, Bejder et al., 2016), whilst others remain at critically low levels (e.g., the North Atlantic right whale, Eubalaena glacialis, Pettis et al., 2018). Concurrently, there has been continual growth of global maritime traffic, which has ultimately increased the risk of vessel/whale collisions (Guzman et al., 2013;Thomas et al., 2016). ...
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Late 19th century technological advances for capturing whales, when combined with the expansion of processing capabilities in the early 20th century, created an industry that could catch and quickly render virtually any whale in any ocean. Here, using the current International Whaling Commission (IWC) database and other sources, we provide the first accounting of the total global catch by industrial whaling operations in the 20th century. In sum, we estimate that nearly 2.9 million large whales were killed and processed during the period 1900-99. Of this total, 276,442 were killed in the North Atlantic, 563,696 in the North Pacific, and 2,053,956 in the Southern Hemisphere. The years 1925-39 in the Southern Hemisphere and 1946-75 in both hemispheres saw the highest totals of whales killed. For the entire 20th century, the largest catches were of fin, Balaenoptera physalus, and sperm whales, Physeter macrocephalus, with 874,068 and 761,523 taken, respectively; these comprised more than half the total of all large whales taken. As noted in other publications, when one species began to decline, another was sought and hunted to take its place. In addition to reported catches, it is now known that the USSR conducted illegal whaling for more than 30 years. The true Soviet catch totals for the Southern Hemisphere were corrected some years ago, and a more recent assessment of the actual number of whales killed by Soviet factory fleet ships in the North Pacific between 1948 and 1979 has provided us with more accurate numbers with which to calculate the overall global catch. The estimate for the total global catch by the USSR is 534,204 whales, of which 178,811 were not reported to the IWC.
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During the winter months, from June to September, humpback whales Megaptera novaeangliae breed and calve in the waters of the Great Barrier Reef (GBR) after migrating north from Antarctic waters. Clearly defined wintering areas for breeding and calving comparable to those identified in other parts of the world have not yet been identified for humpback whales in the GBR Marine Park (GBRMP), mainly because of its large size, which prohibits broad-scale surveys. To identify important wintering areas in the GBRMP, we developed a predictive spatial habitat model using the Maxent modelling method and presence-only sighting data from non-dedicated aerial surveys. The model was further validated using a small independent satellite tag data set of 12 whales migrating north into the GBR. The model identified restricted ranges in water depth (30 to 58 m, highest probability 49 m) and sea surface temperature (21 to 23 degrees C, highest probability 21.8 degrees C) and identified 2 core areas of higher probability of whale occurrence in the GBRMP, which correspond well with the movements of satellite tagged whales. We propose that one of the identified core areas is a potentially important wintering area for humpback whales and the other a migration route. With an estimated increase in port and coastal development and shipping activity in the GBRMP and a rapidly increasing population of whales recovering from whaling off the east Australian coast, the rate of human interactions with whales is likely to increase. Identifying important areas for breeding and calving is essential for the future management of human interactions with breeding humpback whales.
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quite plausible) intrinsic rates of increase for each popu-lation. In the modeling scenarios, the demand for immi-grants would eventually exceed the supply and exhaust the source population, but the simulations demonstrated that high increase rates can be sustained over periods of more than 20 years. This hypothesis, if correct, would not only explain excessively high rates of increase in current " hot-spots " such as eastern Australia, but also imply that for-merly important areas (e.g., Fiji) host few whales today not necessarily because of a failure to recover, but because the species' mating system leads the whales concerned to migrate to higher-density breeding grounds elsewhere. Overall, we caution that assessments of depleted animal populations that do not consider the social behavior of a species are missing a potentially vital component of the picture.
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The upper bound of 0.126 on the maximum demographically possible annual growth rate for humpback whales that has standardly been imposed onrecent 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 modelled 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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From 1976 to 1994, aerial surveys of Southern Hemisphere 'Group IV' humpback whales, Megaptera novaeangliae, were undertaken to provide relative abundance indices of animals migrating northward along the Western Australian coast. These demonstrated a high rate of population increase, at least between 1982 and 1991, of ~10% per year. Surveys were conducted over 10 'good' days in mid-July in an area off Shark Bay, WA, where humpback whales were taken in the last years of Australian whaling, to 1963. The 1994 survey confirmed the increase rate with an estimated population of 4-5,000. The most recent survey, in 1999, planned to obtain an estimate of absolute abundance, was considerably affected by poor weather (only 15 'good' days' flying were possible out of 30 planned over two months). Nevertheless, applying a correction factor for animals missed while submerged to the estimated number of animals sighted gives the 1999 population size within 8,207-13,640. The result is dependent on 'deep diving' time and would be proportionally lower should this dive time be less than the range used (10-15 minutes). We review reported rates of increase and population estimates for this stock in the Antarctic, as well as preliminary Southern Hemisphere population estimates that take account of much larger than officially reported catches in the 1950s-60s. Plans for future surveys are discussed. The population's exploitation history is briefly reviewed.
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Historical reconstruction of the population dynamics of whales before, during and after exploitation is crucial to marine ecological restoration and for the consideration of future commercial whaling. Population dynamic models used by the International Whaling Commission require historical catch records, estimates of intrinsic rates of increase and current abundance, all of which are subject to considerable uncertainty. Population genetic parameters can be used for independent estimates of historical demography, but also have large uncertainty, particularly for rates of mutational substitution and gene flow. At present, demographic and genetic estimates of pre-exploitation abundance differ by an order of magnitude and, consequently, suggest vastly different baselines for judging recovery. Here, we review these two approaches and suggest the need for a synthetic analytical framework to evaluate uncertainty in key parameters. Such a framework could have broad application to modelling both historical and contemporary population dynamics in other exploited species.