Overall, you will be lucky to see a whale shark, as they are not
common in these waters. One sighting gives a specific time (summer
season) when a whale shark stayed near Kavieng. Since Kavieng is 1 ? 2
degrees south of the equator, ?summer? presumably means ?Dec ? Feb.?
Since whale sharks are not common in these waters, it is difficult to
find much information on seasonal occurrence.
Whale sharks are most likely to be found when there are high
concentrations of food, generally when there is an abundance of
plankton or when coral, fish, or crabs are spawning. If the times when
other plankton-feeders are known for Kavieng and Kimbe Bay (not
researched), whale sharks might also be more likely then.
Whale sharks also seem to be more prevalent at lower water
temperatures than generally found at Kavieng and Kimbe Bay. On the
basis of water temperature alone, whale sharks would most likely be
found in these waters in August, when the water temperature is coolest
(27 degrees Celsius). This disagrees with the sighting in the summer
season mentioned above. Food availability may be the ultimate
determining factor.
Whale sharks are probably not common in these areas since a Kavieng
diving site mentions only a single whale shark (off neighboring
Hanover Island) rather than multiple whale sharks:
Re whale shark:
?Big Fish Reef: An exceptional reef, 4km on the seaward side off New
Hanover Island, rises to a plateau at 12 metres (maximum depth 50
metres on the sand) with ridges extending from its corners. Here you
will find the phenomenon that gives this site its name. Great clouds
of barracuda, trevally and batfish wheel around the masses of reef
fish. Eagle Rays are common. Some good hard coral grows down the
slopes of the reef. Orange sponges, sea whips and soft corals grow on
the bottom of the slope. Sharks, including bull sharks, have been seen
here and a whale shark made this site its home during one summer
season.?
Re Kavieng water temperature:
?Diving here is year-round, with January to March subject to sudden
rain squalls and thunderstorms. Typically tropical, these storms are
often replaced by blue skies that arrive back as quickly as they
departed. Best months are usually May to December. The water is always
warm here, averaging a balmy 28-30° Celsius (82-86°F).?
http://www.diversionoz.com/en/g-kavieng.htm
One dive site for Kimbe Bay mentions several different sharks, but not
whale sharks.
http://www.mikeball.com/png/Diving_kimbe_bay.htm
A tourism site mentions whale sharks in the bay, but they aren?t
listed among the most common sharks, but they could have been
mentioned because of their notable size even if they are not common.
"The most common shark species is the gray reef shark , followed by
the placid white tip reef shark, scalloped hammerhead, silvertip, and
blacktip reef shark . The very large and very placid whale shark, is
also seen in Kimbe Bay.?
http://www.tourismwestnewbritain.org.pg/marine.htm
The sentence ?From tiny delicate nudibranchs to the worlds biggest
fish (the harmless Whale Shark) divers are assaulted with a stunning
array of exotic species? is repeated verbatim at a number of tourism
web sites, giving the impression whale sharks are common. Evidence
from other sites makes me skeptical of the implication that whale
sharks are common here.
An Australian review of underwater sights in PNG mentions a number of
fish, but whale sharks are notable for their absence:
?In the Kimbe Bay area there are more than 190 reefs. Dolphins are
often in the area, and snorkeling with them is a great experience.
Everything that is part of the tropical ecosystem exists in this bay.
Within Kimbe Bay you can see everything, coral reefs, invertebrates,
colourful fish life, dolphins and sometimes even Orcas. Many of the
reefs have resident schools of barracuda, tuna and jacks. My personal
favourite is Inglis Shoal which rises from very deep water to within
12 metres of the surface. It is buzzing with life including Dogtooth
Tuna, Barracuda and Bigeye Trevally.?
http://www.underwater.com.au/article.php/id/1690/
Another site indicates that whale sharks can occasionally be seen in
Kimbe Bay but doesn?t give the time of year.
?Whale sharks (Rhiniodon typus) are occasionally seen in Kimbe Bay.?
?Water temperature averages 28 to 31°C (83 to 88°F) each day.?
http://www.uga.edu/cuda/Mahonia.html
One dive sight mentions that the water temperature can occasionally be
in the range which whale sharks favor:
?Water temperature rarely goes below 85 degrees (20 C degrees) during
the winter (June to August)?
However, this temperature is definitely below the average water
temperature for those months (see below).
http://www.febrina.com/PlanningGuide.html
The lowest average water temperature in Kavieng and in Kimbe Bay
occurs in August (27 degrees Celsius) and this is closest to the water
temperature generally favored by whale sharks.
http://www.mikeball.com/weather.htm
-------
The rest of this information doesn?t help much in determining when
whale sharks on most common in Kimbe Bay and Kavieng.
There are a few areas in the world where whale sharks can be reliably
observed, but PNG does not seem to one of them:
?Whale sharks are found world-wide in all tropical and warm temperate
seas except for the Mediterranean. They are occasionally recorded in
oceanic waters but are most commonly reported in feeding aggregations
close to the coast. Although widely distributed, they are generally
infrequently recorded except in a few apparently favoured coastal
areas, where they are usually seen in relatively large numbers (tens
to low hundreds) for only a few months of the year. Range states are
listed in Annex 1.
Distribution records are characterised by highly seasonal appearances,
with aggregations of whale sharks appearing for a few months in
locations where their zooplankton food is abundant as a result of
regular fish or invertebrate spawning events (Fowler 2000, Norman in
press, Heyman et al. 2001). The species is certainly highly
migratory, with satellite tracking of individuals demonstrating some
very long-distance and long-term migrations, including a journey of
over 2000km (at time of printing) toward Asia off the northwest
Western Australian coastline in 2002 ??
?Despite undertaking such long distance migrations, tagging and
photo-identification studies have demonstrated that individual sharks
will return to the same feeding area in subsequent years (Taylor
1994, Norman 1999, Graham et al. in prep.).?
?Habitat availability is not considered to be a constraint for this
species, unless associated with seasonal food concentrations (nursery
and mating grounds have not been identified). Critical habitats
presumably include coral reefs (which are extremely vulnerable to
habitat damage and disturbance) where whale shark aggregations are
associated with synchronous spawning of corals (Western Australia)
and fishes (Belize). Whale sharks are reported also to appear at
Christmas Island following land crab spawning events (Norman 1999),
and to frequent shallow-water areas near estuaries and river mouths
in northern Borneo and the Philippines (Alava et al. 1997, Alava et
al. in press, Alava and Kirit 1994), sometimes during seasonal shrimp
blooms.?
?The longest-established ecotourism industry focused on whale sharks
is based at Ningaloo Reef, Western Australia, where regulations
control numbers of vessels and snorklers, contact time and approach
distances in order to minimise disturbance to the sharks (Norman
1999). Some 1,000 people visited this site between March and June
1993 to see whale sharks. This increased to almost 3,000 in 1996
(Colman 1997), with the number of participants even greater in 2002
(Norman pers com).?
http://www.cites.org/eng/cop/12/prop/E12-P35.pdf
The following is from an Australian government site regarding an
Australian reef known to reliably attract whale sharks:
?From mid-March to mid-May each year visitors from all around the
world converge on Ningaloo for the experience of a lifetime?diving
with the awesome whale shark, the world's biggest species of fish.
Ningaloo Reef is the only easily accessible place in the world where
these giants appear in large numbers at predictable times of the
year.?
?Best Season: ?If you want to see whale sharks you need to visit
between April and early July. SCUBA diving is good all year round.
Water temperatures range from the low 20s to the low 30s (°C).?
http://www.calm.wa.gov.au/national_parks/previous_parks_month/ningaloo.html
Ningaloo is about 22 degrees south, as contrasted to Kievang and Kimbe
Bay, which are much closer to the equator.
?Studies reveal that this shark prefers warm waters, with surface
temperature around 21-30º C, marked by high primary productivity (much
plankton).?
(The monthly water temperature in Kimbe Bay and Kavieng varies from 27
to 30 degrees Celsius, which is at the upper end of the preferred
range.)
http://www.flmnh.ufl.edu/fish/Gallery/Descript/Whaleshark/whaleshark.html
?R. typus inhabit ocean waters with surface temperatures between 70-77
degrees Fahrenheit.? (= 21 ? 25 degrees Celsius)
http://animaldiversity.ummz.umich.edu/site/accounts/information/Rhincodon_typus.html
?The whale shark feeds on a wide variety of planktonic and nektonic
prey, including small crustaceans, small schooling fishes, and
occasionally on tuna and squid. It does not rely on forward motion for
filtration, but can hang vertically in the water and suction feed by
opening its mouth and allowing water to rush in.
Sea temperatures in the 21-25°C range, near cold water upwellings, are
preferred because these conditions are probably optimal for its prey.
Their movements are thought to be related to local productivity
events.?
http://www.marine.csiro.au/LeafletsFolder/51wshark/51.html
?It is found in most tropical, temperate seas across the world and
seems to prefer warmer waters ranging in temperature from 21C to 28C
(70F to 82F).?
http://www.aboututila.com/ScubaInfo/Whale-Sharks/Whale-Shark-Facts.htm |
