1. Alison Lynch
UID: 111677979
BSCI338B: Marine Biology
Due: December 2nd, 2015
Reproductive success in whale species due to sonar interference
Marine mammals are a vital part of the marine ecosystem. Whales, dolphins, seals, and
sea lions are some of the most beloved creatures in the sea, which is part of why so many
organizations have been fighting to protect them for years. As a general characteristic between
them, they all “use sound for activities essential to survival and reproduction” (Holt, 2009).
Communication and echolocation are both key behaviors and when these are disrupted, it could
mean devastation for some species. Recently various human actions, mainly the Navy’s use of
sonar noise, have impacted the reproductive success of whales in the Atlantic Ocean. Sonar
interferes with not only diving patterns, but also as a result foraging and mate selection in many
species. It is vitally important that people are aware of the implications these types of activities
have on the lifestyles of cetacean species such as the endangered right whale (Eubalaena
glacialis) pictured in figure one below.
The oceanic atmosphere has been changing in recent years and this change is mainly
attributed to the navy’s use of sonar systems in their training. A recent study estimated that ocean
noise is rising at a rate of approximately 3–5 dB per decade at some frequencies in some
locations” (Reeder, 2006). At first glance, this does not seem like a significant increase, but for
whales, this is enough to cause problems. This rise has specifically been attributed to
“anthropogenic sources such as Navy sonar systems” because this is a clear change that has
happened in the time range that would directly increase the noise levels (Reeder, 2006). The
Marine Mammal Protection Act is already in place and have placed restrictions on what the
military can do in marine waters; it “establish[es] marine mammal mitigation zones around each

2. Alison Lynch
UID: 111677979
BSCI338B: Marine Biology
Due: December 2nd, 2015
vessel using sonar [and] ensure[s] that explosives are not detonated when animals are detected
within a certain distance” (www.noaanews.noaa.gov). While these precautions are in place, this
still does not address the fact that the oceanic noise level is increasing. Sound carries
significantly through water and therefore better changes need to be made because of its impacts
on marine mammals, such as whales.
One such behavior that these oceanic noises affect is the whales’ diving patterns which
are important not only for foraging, but also reproduction. In one study, diving behavior was
monitored in killer whales (Orcinus orca), pilot whales (Globicephala melas), and sperm whales
(Physeter macrocephalus) “during controlled exposures to naval sonar [low frequency active
sonar (LFAS): 1–2 kHz and mid frequency active sonar (MFAS): 6–7kHz] during three field
seasons (2006–2009)” (Sivle, 2012). In the study they found that the changes in diving behavior
significantly decreased efficiency in foraging in the animals because they were forced out of
paths that they normally took to get food. Many whales have specific dietary needs and therefore
disrupting the depth with which they are foraging at could lead to different prey items. As a
result, individuals may not be able to survive as well and so this is a very important consideration
for those using sonar. Another factor that goes along with foraging is the importance of blubber
build up in whales. For whales, blubber “serves a number of functions, including maintaining the
hydrodynamic shape of the body insulating the body core adjusting buoyancy and storing energy
reserves” so proper build up of these reserves is critical to the survival of these whales (Miller,
2011). If whales are forced out of their normal feeding spots, then they may not be able to build
up the necessary blubber to swim properly, as well as have the energy to reproduce. This is
mainly important for females as reproduction is so much more energetically costly to them than

3. Alison Lynch
UID: 111677979
BSCI338B: Marine Biology
Due: December 2nd, 2015
males. It is a known fact that “adult females measured prior to the start of pregnancy had the
thickest blubber of all life history classes” of the species (Miller, 2011). This is unsurprising
given knowledge of mammalian reproduction and the investment in egg production. In a study
done in 2005, “12% of adult females were reproductively inactive [in their study] which may be
a consequence of females not attaining adequate body fat reserves necessary for successful
reproduction” based on their overall findings. (Miller, 2011). Realistically, if these female
whales are not able to dive to the feeding grounds they are used to, then they will not have the
blubber reserves in order to reach their maximum fecundity and therefore in a species such as the
right whales which are endangered, they need every opportunity to have successful reproductions
as possible. These sound deterrents also affect sexual selection in whales.
Sound communication is used by many cetacean species and is a primary form of sexual
selection for the majority of species. One such example is seen in humpback whales (Megaptera
novaeangliae). Mature, male humpback whales have been known to “start singing while still on
their feeding grounds to gain access to more females” (Magnusdottir, 2014). Going back to the
previous argument about feeding grounds, if males have to move their feeding grounds to avoid
sonar, then it is possible that both foraging and reproductive success would suffer. These songs
can be viewed as “similar to both leks and to male dominance polygyny, in which males display
(sing) or directly compete (perhaps sometimes in coalitions) for access to females” (Clapham,
1996). This means that the songs determine mating success in the males. Therefore it is very
important that these songs are actually carried through the water so that the females can hear
them unobstructed. If sonar noise were to be happening on breeding grounds, then reproduction
across the board may deplete. Male whales would have to “compensate for background noise by

4. Alison Lynch
UID: 111677979
BSCI338B: Marine Biology
Due: December 2nd, 2015
changing their signal’s amplitude, duration, repetition rate, and/or frequency” which could have
various consequences (Holt, 2009). For one, the females may not like the changes to the songs
and therefore not allow copulation with those males. Also this compensation most likely has
“energetic costs, [that] lead to increased stress levels” which is also detrimental to the survival of
those males (Holt, 2009). If they have to expend more energy on producing their songs, then they
are going to need more food resources, but if the noise obstructs their diving patterns, then they
will not receive proper nutrition and so their survival rates will decrease. In a species such as the
right whales, this is not going to help bring them out of their endangered status. One study done
in 2000, suggested “that humpbacks sang longer songs during sonar transmissions to compensate
for acoustic interference” (Miller, 2000). Increasing song length intuitively would correlate with
using more energy and therefore these sonar trainings are detrimental to these whale species. The
noises cause individuals to waste energy which should be put towards their survival. For species
such as the right whale, energy should not be wasted because of human interaction.
The endangered right whale (Eubalaena glacialis) normally forms surface active groups.
These groups’ primary function is to “encompass both reproductive and non-reproductive
behaviors,” and the composition of these groups are described as “fluid, with individuals leaving
and joining the group through time” (Parks, 2007). Communication is important not only within
the groups, but between them also. As stated previously, sexual selection happens in whale
species and this is no different for the right whales. Once in these groups males sing in order to
gain reproduction opportunities. If sonar testing is taking place in nearby waters this will put
strain on these groups and reproductive success could easily plummet. Also if a whale is trying
to find a new group, the sonar interferences may cause the individual to not hear other groups or

5. Alison Lynch
UID: 111677979
BSCI338B: Marine Biology
Due: December 2nd, 2015
just not encounter them because they have not swum in the correct direction due to the noise.
Part of the reason they have formed these groups in the first place is to “to increase the likelihood
for success during the actual mating event, or if males are establishing dominance relations that
affect later mate acquisition” (Parks, 2007). Because this species in particular is nearing
extinction, it is ever more important that humans not interfere with behaviors that have evolved
to help them thrive. Better regulations must be made in order to save the species. Many
researchers are hopeful and believe that “through a continued and expanded monitoring program
and the restriction of potentially harmful activities in right whale habitats, perhaps the North
Atlantic right whale population will not just survive, but steadily grow” (Knowlton, 1994). Their
habitat, as their full name suggests in the entire north Atlantic as shown in figure two. This area
of the ocean is a prime route for not only military training but also transatlantic ships that are
transporting goods, etc. These companies and organizations need to be made more aware of the
impacts they have on such a species.
Figure 1: North Atlantic Right Whale
(IUCNredlist.org)
Figure 2: Geographic Distribution of Right
Whales (IUCNredlist.org)

6. Alison Lynch
UID: 111677979
BSCI338B: Marine Biology
Due: December 2nd, 2015
Recently the Navy’s use of sonar noise in addition to other human actions has impacted
the reproductive success of whales in the Atlantic Ocean. Sonar noise interferes with cetacean
diving patterns, foraging, and mate selection in many species. People need to be aware of the
implications these types of activities have on the lifestyles of marine mammals such as the
endangered right whale (Eubalaena glacialis) because their status depends on it. If these
situations get bad enough, even more marine mammals will become endangered and ultimately
extinct. As they are such an important creature in the marine ecosystem, more regulations must
be made specifically in the military training but also oceanic travel in general.
Works Cited:
Barclay, Connie. "Noaa Announces Regulations to Protect Marine Mammals During Navy
Training and Testing in Atlantic and Gulf of Mexico." National Oceanic and
Atmospheric Administration 2013. Web. November 25 2014.
Clapham, PJ. "The Social and Reproductive Biology of Humpback Whales: An Ecological
Perspective." Mammal Review 26.1 (1996): 27-49. Print.
Holt, MM, et al. "Speaking Up: Killer Whales (Orcinus Orca) Increase Their Call Amplitude in
Response to Vessel Noise." Journal of the Acoustical Society of America 125.1 (2009):
EL27-EL32. Print.
KNOWLTON, AR, SD KRAUS, and RD KENNEY. "Reproduction in North-Atlantic Right
Whales (Eubalaena-Glacialis)." Canadian Journal of Zoology-Revue Canadienne De
Zoologie 72.7 (1994): 1297-305. Print.
Magnusdottir, EE, et al. "Humpback Whale Songs During Winter in Subarctic Waters." Polar
Biology 37.3 (2014): 427-33. Print.
Miller, CA, et al. "Blubber Thickness in Right Whales Eubalaena Glacialis and Eubalaena
Australis Related with Reproduction, Life History Status and Prey Abundance." Marine
Ecology Progress Series 438 (2011): 267-83. Print.

7. Alison Lynch
UID: 111677979
BSCI338B: Marine Biology
Due: December 2nd, 2015
Miller, PJO, et al. "Whale Songs Lengthen in Response to Sonar." Nature 405.6789 (2000):
903-03. Print.
Parks, SE, et al. "Occurrence, Composition, and Potential Functions of North Atlantic Right
Whale (Eubalaena Glacialis) Surface Active Groups." Marine Mammal Science 23.4
(2007): 868-87. Print.
Reeder, Benjamin D, Rommel Pucan, and Curtis A Collins. "Long-Tern Trends in Ocean
Noise." The Journal of the Acoustical Society of America, 2006. 3382. Vol. 120. Print.
Sivle, L.D., et al. "N Dive Behavior During Naval Sonar Exposure in Killer Whales, Long-
Finned Pilot Whales, and Sperm Whales." Frontiers in Physiology, 2012. Print.