Dolphin Watching Boat Trips in Wales..

We have started trips for the 2019 season. Over Easter we will only be doing one trip a day due to large tides. Call early to book.Join us on a one and a half hour guided Dolphin Watching Boat Trip, leaving from the picturesque fishing village of New Quay, West Wales. Learn about the local history, geology and wildlife from our marine biologist guides and knowledgeable skippers.
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Marine Biologist Guide

Seeing a whale or dolphin leap out of the water and crash down with an
almighty splash is undoubtedly one of the most spectacular sights at sea.
The scientific definition for such an aerial display is a ‘breach’, an
intentional jump from the water in which at least 40% of the animal’s body
emerges.

Of all the cetaceans, humpback, right and sperm whales, and offshore
dolphins, are the most frequent breachers. Each have slightly different
styles of approach to the surface and aerial acrobatics. Sperm whales and
dolphins approach the surface vertically from depth, whilst humpbacks and
right whales make a shallower horizontal approach to gain speed until the
final seconds in which they raise their heads and flukes, twisting using
their flippers to launch themselves into the air. Considering a humpback
whale can reach a weight of 40 tonnes, this energetic display is seriously
impressive. Above the surface, breaching form is also varied. For large
whales, the animal classically twirls to land on its back or side,
revealing around 90% of its body at peak emergence. More rarely big whales
may belly flop, of course with an enormous accompanying splash. Smaller
cetacean species, or whale calves, can completely clear the water in a
breach. Young spotted dolphins have been recorded to leap an astounding 15
feet into the air – higher than a double decker bus! Breaches are also
often performed in series, one after the other. One humpback whale in the
West Indies was seen to breach 130 times in a 75-minute period, which
would use up a LOT of energy.

So why do cetaceans breach? Despite it being a common activity performed
by many whales and dolphins, scientists still don’t really know why. Lots
of plausible theories have been proposed. Several, or all, of these
hypotheses could be true, depending on the environmental and social
context, and cetacean species in question. So, let’s explore a few of
these explanations.

Communication

Breaching behaviour seems to be strongly correlated with sociality.
Breaching rates tend to be higher for the more social species, and when
group sizes are larger. For the more solitary species, such as blue and
Bryde’s whales, breaching occurs only rarely. Why is this?

In socially structured groups, communication is extremely important for
co-ordinating group activities, fission and fusion. In spinner dolphins
and humpback whales, breaching occurs most during changes of group
activity or composition, such as initiation of a feeding bout. For
example, spinner dolphins increase aerial behaviours during the transition
from the resting period to the foraging period in their 24-hour cycle;
when individuals are widely dispersed; or when visibility is low at night.
During migration, cetaceans seldom feed, yet aerial behaviours are often
observed despite using up lots of energy. It has thus been suggested that
breaching may mediate social interactions by maintaining contact between
groups.

The sound of a body slamming to the surface after a leap will propagate
only short distances compared to cetacean vocalizations in water. Thus,
the acoustics of a breach will only transmit information to individuals
close-by, avoiding unwanted signalling to prey, predators or conspecifics.
These signals probably transfer information on motivation or intent.

Neighbouring animals are unlikely to be able to see the breachers body
above the surface, so it is the sound produced from hitting the surface
that must transmit information. It is proposed that breaching is part of
an ‘honest signalling system’, in which important information about the
signaller is transmitted to receivers. The sound, and under-water bubble
pattern, produced by a breach reliably indicates the physical abilities of
the breaching individual, such as strength and agility. The larger the
splash, the bigger the individual and the faster it has propelled itself
out of the water. During a breach, a humpback whale uses about 1% of its
daily energy expenditure. If breaches are performed in sequence, this is a
significant utilisation of energy. This signals to others that the
individual can afford ‘wasting’ energy on jumping out of the water,
showing off its physical fitness.

During the humpback whale breeding season, breaching activity is more
frequently observed. Male groups competing for a female breach regularly,
supposedly displaying their physical strength and endurance. So, breaches
can be used to assert dominance over others, or attract mates during
courtship.

A breach may also add emphasis or draw attention to some other signal,
such as a vocalization or visual display, sort of like a ‘physical
exclamation mark’.


Play

‘Play’ is a blurry concept, and is often attributed to any behaviour
without an obvious biological function. Breaching is common in social
situations and among young cetaceans – characteristics of playful
behaviour. It is usually calves and juveniles that leap the highest, and
in right, gray, and humpback whales, animals will breach when only a few
weeks old. Perhaps this acrobatic activity helps the development of
musculature, body awareness, and co-ordination. Yet this doesn’t really
satisfactorily explain why adult whales breach too.

Cleansing

For a cetacean, little creatures such as barnacles, remoras, lice, that
hitch-hike attached to their bodies can be quite annoying. These
ectoparasites not only increase the drag force and the energy costs of
movement, but are also itchy. One humpback whale was found with 454kg of
barnacles attached to its body, just imagine lugging all that extra weight
around! Breaching can act to dislodge or loosen these critters, helping to
remove them. For example, 44% of Hawaiian spinner dolphins that breached
had remoras (small fish that latch on via disk-like suckers) attached,
suggesting that breaching may be an attempt to shake off the extra
passengers. But this still doesn’t explain why the other 66% of spinner
dolphins were breaching ….


Feeding

A hefty cetacean body slamming the water would be enough to scare anyone.
One hypothesis is that breaching is used to stun, scare, or herd prey,
such as schools of fish. Lobtailing (tail slapping) is often used for this
purpose and is sometimes associated with breaching. This may explain some
breaches, but not those observed in non-feeding circumstances.

A bit of everything

It seems that there is no single all-scenarios-covered explanation for why
cetaceans breach. In general, breaching seems to be associated with social
situations, indicating an important role in communication. Depending on
the social and environmental context, leaping out of the water can have
different functions. Identifying which function a breach serves is
challenging to say the least, with solid explanations still evading marine
scientists.

Written by Liz Heard, one of our marine biologist guides. 

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