Wilson, S.C.1, Trukhanova, I2, Crawford, I1, Dolgova, E3, Dmitrieva, L4, Goodman, S. J.4
Assessment and mitigation of the impacts from icebreaking vessels on ice-breeding
pinnipeds in the Holarctic
1. Tara Seal Research, N. Ireland, UK
2. Baltic Fund for Nature, St. Petersburg, Russian Federation
3. Lomonosov Moscow State University, Russian federation
4. School of Biology, University of Leeds, UK
Traffic from tanker, cargo, industrial support and cruise ships is increasing in Arctic waters,
driven by expansion of oil and gas (O&G) related activity, mineral extraction, tourism, and
by the opening up of new trans-polar shipping routes allowed by reduce sea-ice cover
(McGarrity & Gloystein 2013). This rapid escalation in shipping is predicted to lead to
increased physical interactions with ice-bound marine mammals (Huntington 2009).
Understanding and concern over this type of vessel impact is in its infancy, but on the basis
of their ecology and life-history, ten Holarctic pinniped species are expected to be
vulnerable to the impact of shipping in four main Arctic transport routes and local shipping
routes serving O&G installations as well as shipping routes in the Baltic and Caspian seas and
Alaskan glacial waters (Table 1, Fig. 1). Here we review the current state of knowledge on
actual and predicted impacts, aspects of pinniped ecology likely to predispose vulnerability
to shipping impacts, and suggest potential mitigation strategies that might be employed by
policy makers and vessel operators.
Vessel passage through the breeding grounds of ice seals has long been predicted to impact
both on habitat and individuals. Nursing pups of ringed seals (Pusa hispida) and bearded
seals (Erignathus barbatus) have been affected by collisions, crushing, or displaced ice
(Anon. 1982). Similar impacts have also been reported for the harp seal (Phoca
groenlandica) in the White Sea (Vorontsova et al. 2008) and the Caspian seal (Pusa caspica)
(Hӓrkӧnen et al. 2008, Wilson et al. 2008). In addition to ship strikes and whelping site
breakage, icebreaker impact is likely to include separation of mother-pup pairs,
displacement from their natal site, and small pups in lanugo being wetted in ice-chilled
waters. These impacts will result in energy loss to mother and pup and also stress to the
mother, which may affect lactation, with consequential detrimental effects on pup survival
(Wilson et al. 2008). Risk of collision and other serious impact is likely to be influenced by
visibility and vessel speed.
Pinniped species may differ in the extent to which mothers with pups are sedentary at a
specific nursery site during the lactation period and the extent to which they are visible on
the ice surface. The survival of pups of species with whelping site tenacity are likely to be
more vulnerable to nursery habitat destruction by icebreaking vessels than those species
using the ice only as a haul-out platform.
Sedentary pupping species. The sedentary Holarctic ice-breeding pinniped species pup
mainly on relatively stable fast or pack ice where the whelping site is predictably relatively
stable for the duration of the nursing period. These species are the Caspian (Pusa caspica),
harp (Phoca groenlandica), ringed (Pusa hispida) and hooded (Cystophora cristata) seals.
Caspian and harp seals generally have a well-developed nursery site, often for a small group
of mothers and young, which incorporates a network of birth sites, pup shelters, wateraccess holes and seal tracks. Mothers and other adults learn the topography of their
breeding site and learn to navigate back to it (Kovacs 1995). Pup survival is therefore
dependent on the integrity of the nursery site and structures lasting through the nursing
period (Lavigne and Kovacs 1988; Wilson et al 2012). Caspian breeding adults generally
respond to icebreaker approach by moving away only at distances less than ~100m
(Hӓrkӧnen et al 2008, Wilson et al. 2008). Caspian and harp seal pups innately follow their
mothers, who usually try to lead their pups away from danger (Wilson et al. 2012; Kovacs &
Innes 1990), although both adults and pups of the harp seal may display a ‘paralysis’
response to approaching danger (Lydersen & Kovacs 1995) and may therefore fail to move
away.
Vessels breaking through fast or pack ice create channels of brash ice which may remain if
the ice does not refreeze rapidly. Caspian and Baltic grey seals (Halichoerus grypus) have
been recorded as using these channels as leads into the ice and Caspian seal females often
create whelping sites along the edge of these open channels, behaving as if they were
natural polynia (Hӓrkӧnen et al. 2008, M.Jussi, pers.comm.); this places them at risk from
further shipping in the same channel
Pups of the ringed seal are concealed in lairs for about 6 weeks and are therefore vulnerable
to icebreaker destruction, since the only visible indication of lairs at the surface may be ice
holes or adults on the ice (Frost and Lowry, 1981; Lydersen and Gjertz, 1986). Breeding
ringed seal adults abandon breathing holes and lairs due to seismic survey guns most often
within 150m (Kelly et al 1988) while most reactive behaviour towards icebreakers was at
distances up to 230m (Brueggeman et al. 1992). Hooded seal pups are born usually on pack
ice and pups remain at their natal site until they gradually enter the water, even though the
mother departs after ~4 days (Lavigne & Kovacs 1988).
Pups of sedentary species vary in the ability of pups to withstand immersion in ice water
due to ship passage. Small-bodied pups in lanugo with a relatively long nursing period of ~ 46 weeks, such as Caspian pups, are behaviourally programmed to avoid water and their
survival is compromised if forced into ice water, although ringed seal pups from ~25 days
can enter the water if disturbed (Lydersen and Hammill, 1993). The larger pups of the
hooded seal naturally enter the water gradually after weaning at ~4 days (Lavigne and
Kovacs 1988) but the impact of premature entry into the water is not known.
Relatively mobile pupping species. Grey seals in the Baltic pup on drift ice floes which are
thick and large enough to provide a stable site for the whole of the nursing period. Even if a
floe bearing a pup drifts long distances at high speed, mothers will still follow the floe and
attend the pup (Jüssi et al. 2008). Destruction of a pupping floe would probably result in
death of a young pup. However, the relatively large grey seal pups are able to swim
competently from about 10 days of age (Jüssi et al. 2008). Ribbon seals (Histriophoca
fasciata) are also born on mobile ice floes, mothers selecting floes with clean, white, broken
pack ice. Ribbon seal adults show little avoidance or flight response to boats (Burkanov &
Lowry 2008) and are therefore at great risk of ship collisions. Harbour seal (Phoca vitulina)
pups born on glacial ice in Alaska are thought to experience cold stress and energy deficit
when flushed into the water by cruise vessel approach (Jansen et al. 2010).
Mobile pupping. Spotted seal (Phoca largha) male-female pairs and pups may be relatively
mobile on the unstable ice front, sometimes moving considerable distances and taking
shelter from storms beside pressure ridges (Pugh et al. 1997). New-born pups of the
bearded seal are very large-bodied and are competent swimmers from birth. Mothers and
pups may move between ice floes, just using floes in loosely packed ice of favourable size
and location as a temporary haul-out platform (Burns 1981b; Hammill et al. 1994; Kovacs et
al. 1996). Walrus (Odobenus rosmarus) are very mobile, using available ice floes as haulout, whelping site and nursing platforms (Boltunov et al. 2010), although there is evidence
for moderate ice floe site tenacity in Pacific walruses at least in late winter and late summer
(Wartzok and Ray, 1980). Walrus groups in the Chuchki sea showed an ‘escape’ response to
icebreaking activity within 230m and some at greater distances (>1km); mothers and calves
are likely to escape into the water, causing small calves to be energetically compromised
(Brueggeman et al. 1991). When a walrus herd including calves is disturbed, the resulting
stampede is likely to result in animals, especially calves, being crushed (Anon 1990).
Walruses give birth only once every 2–3 years and care for the calf for that length of time
(Boltunov et al. 2010). The long-term survival of breeding populations of walrus on ice is
therefore highly vulnerable to vessel traffic disturbance (Lowry et al. 2008).
The need for shipping regulations to protect pinnipeds breeding on ice
Huntington (2009) suggests that regulation of shipping, with clear operational guidelines to
mitigate impact on marine mammals, should be developed in advance of a shipping boom
rather than retroactively, and further suggests that such conservation measures developed
elsewhere may have application within the Arctic. We propose that evidence-based
regulations be developed specifically to protect ice-breeding pinnipeds. The type of
evidence required should come from studies undertaken onboard vessels to record, for
different species, the types of habitat breakage and disturbance, distance at which motherpup pairs will start to move away, likelihood of mother-pup separation at different distances
from the vessel, vulnerability of pups whose mothers are absent and effect of vessel speeds
and visibility conditions due to weather and darkness (Hӓrkӧnen et al. 2008, Wilson et al.
2008). This would allow development of evidence-based risk assessments integrating
information on species distribution and ecological profile, to inform the development of
shipping regulations necessary to mitigate impacts. These should include:
(a) The use of advance planning by O&G, mineral extraction and cargo transport companies
to minimise the number of shipping transits required in the vicinity of pinniped breeding
areas during the pupping season. Such advance planning would require companies to
engage in ongoing consultation with pinniped biology specialists.
(b) Obligatory planning of shipping routes to avoid pinnipeds on ice. Aerial surveys in the
Beaufort Sea have been flown annually since the 1990s to provide baseline information on
marine mammal distribution and abundance relative to drilling operations and to advise
operating vessels as to the presence of marine mammals (Anon 2009). Due to the growing
awareness of the impact of icebreakers on breeding harp seals (Vorontsova et al 2008),
aerial surveys were flown in the White Sea in 2009 to detect seal concentrations and pass
this information to captains. These seal distribution data were combined with satellite
images (donated by Scanex) of icebreaker tracks to determine how successful captains were
at avoiding seals (A. Filipova, pers. comm.). However, funding was not available in
subsequent years to continue this project. Sustainable route planning systems funded by
icebreaker operators need to be developed. Satellite imaging has been found to be of
insufficient resolution to detect breeding colonies of seals such as the harp seal (A. Filipova,
pers. comm.). This is partly because harp seals are relatively small-bodied and also because
females giving birth tend to allow some metres between individuals, although satellite
imaging may be more appropriate for larger-bodied species in dense aggregations, such as
walrus. Ice buoys may also be used to track the movement of seal colonies due to ice drift
(D. Glazov, pers. comm.). UAV or tethered balloon technology might also be developed to
detect seals ahead of vessels.
(c) Onboard mitigation measures by captains. Captains should be given incentives to reduce
speed in seal areas, navigate sensitively so as to manoeuvre around seals when necessary
and ensure adequate vision (using thermal imaging cameras) at night or weather conditions
with poor visibility.
(d) Development of a marine mammal observer (MMO) system specifically designed to
monitor icebreaker/pinniped encounters. A legal framework for regulating shipping through
pinniped ice areas is required. This should be on a par with MMO monitoring and reporting
procedures which have become standard practice world-wide for O&G industry vessels
engaged in seismic surveying and drilling operations (Weir and Dolman, 2007; Compton et
al. 2008), largely due to the growing awareness of the adverse effects of noise on cetaceans
(Cosens and Dueck 1993; Jepson et al. 2003; Gordon et al. 2004). A full MMO system has
now been developed in the Beaufort and Chukchi Seas, in accordance with the US
government agency NMFS requirements. Each vessel should carry a sufficient number of
qualified MMOs to provide 100% coverage during drilling operations during daylight (Anon,
2009). Vessels for Sakhalin Energy also carry qualified MMO teams and the MMO reports
make monitoring results available to the Russian authorities as well as to the public and
other researchers (Anon 2005). A system of independent Seal Observers for ice pinnipeds
needs to be established. This will require its own briefs and standards distinct from existing
MMO systems, since the requirements for recording types of impact of icebreakers on
pinnipeds on ice are very different from the type of MMO recording for drilling and seismic
surveying.
Type of vessel transiting Arctic ice.
One final consideration of impact and mitigation on seals in Arctic ice is the nature of the
vessels. Modern nuclear-powered icebreakers can break through ice up to 2m thick along
the Northern Sea route or 2.5m thick in central parts of the Arctic Ocean at speeds of up to
10 knots (Wikipedia.org). Fatal impact on pinnipeds is highly likely at this speed. New
‘oblique’ icebreakers are now being developed which can attack the ice at a 30° angle rather
than head-on, thus breaking broader areas of ice (Carson, 2014). Such ice-breaking tactics
should not be permitted in the vicinity of seal breeding areas.
Research required or evidence-based mitigation of shipping impact
Mitigation measures recommended for shipping transiting potential pinniped ice areas need
to be evidence-based. Foremost, safe operating distances which do not cause disturbance
for each species need to be determined. Species-specific data on adult, mother and pup or
calf response to icebreaker approach needs to be ascertained and a risk assessment carried
out for each species and Holarctic ice region subject to shipping traffic. It should be possible
to coordinate trained and experienced Seal Observers to carry out the necessary onboard
research in addition to monitoring and reporting to the designated authorities on vessel
impact on each trip.
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Table 1. Holarctic pinniped species potentially impacted by icebreakers or cruise ships.
Arctic ocean
NWP NSR TSR ABR
Other ice-bound areas
Balti Caspian Alaska
c
Phoca groenlandica
X
X
X
X
Pusa hispida
X
X
X
X
X
Erignathus barbatus
X
X
X
X
Odobenus rosmarus
X
X
X
X
Cystophora cristata
X
X
X
Histriophoca fasciata
X
Phoca largha
X
Pusa caspica
X
Halichoerus grypus
?x
?x
X
Phoca vitulina
X
X
NWP- NorthWest Passage; NSR-Northern Sea Route; TSR-Transpolar Sea Route; ABR-Arctic
Bridge Route
Fig. 1. Principal ice-breaking vessel routes in Holarctic regions