Photographs copyright Andy
Murch. All rights reserved.
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Porbeagle Shark Pictures
Conical snout. Large black eyes.
Teeth narrowly triangular.
fin high with distinct white patch on free rear tip (trailing edge). Caudal fin
crescent shaped with pronounced caudal keel. A second, much shorter caudal keel on lower
caudal lobe. Dorsal coloration
slate grey. Underside pale.
Maximum recorded size 3m but may exceed 3.7m. More commonly 2m. Size at birth 60-80cm
and oceanic in depths of up to 700m. Migratory.
A large but fragile population covers the temperate
North Atlantic Ocean. Smaller isolated populations in the southern hemisphere
around south Australia, southern South America, South Africa, and far southern
populations may be linked by migration.
Diet and Behavior: In
summer moves inshore possibly in search of prey species.
Main diet consists of small bony fishes, dogfish, soupfin sharks (tope) and squid.
Litter size around 4 pups.
Foetal sharks feed on unfertilized eggs.
Conservation Concerns: Listed by the IUCN as 'Vulnerable'. The porbeagle
is a wide-ranging, coastal and oceanic shark, but with apparently little
exchange between adjacent populations. Low reproductive capacity and high
commercial value (in target and incidental fisheries) of mature and immature age
classes makes this species highly vulnerable to over-exploitation and population
depletion. This depletion, despite variations in availability of data and degree
of depletion between the northern and southern hemispheres, is considered to
meet Vulnerable criteria globally. The eastern and western North Atlantic
populations have both been seriously over-exploited by directed longline
fisheries. Collapse of the Northeast Atlantic population led to intensive target
fishing in the well-documented Northwest Atlantic fishery in the 1960s, with
most of the virgin biomass removed in just six years. Renewed target fishing in
the 1990s led to a further population decline to ~11 to 17% of virgin biomass
within the three generation period for this species. Recently improved
management in the Northwest Atlantic should now help stocks to recover, however
the Northeast Atlantic population has been subject to unrestricted fishing
pressure ever since its earlier crash. Data are lacking, but stock depletion is
considered to be much greater than in the Northwest Atlantic. Longline tuna and
swordfish fleets in the southern hemisphere take a significant partially-utilised
bycatch. Only limited trend data are available, including over 90% declines in
landings by the Uruguayan longline fleet in the southwest Atlantic.
Citation: Stevens, J., Fowler, S.L., Soldo, A., McCord,
M., Baum, J., Acuņa, E., Domingo, A. & Francis, M. 2006. Lamna nasus. In: IUCN
2013. IUCN Red List of Threatened Species. Version 2013.1. <www.iucnredlist.org>.
Bay of Fundy, Canada.
The Pacific equivalent of the Porbeagle Shark is the Salmon Shark (Lamna
ditropis) which can be
distinguished by its heavier set body, dark trailing edge of its dorsal fin, white
pectoral fin bases and blotchy coloration.
The Porbeagle shares part of its range with the Great White Shark and the
Reaction to divers:
Very difficult to approach. After chumming for many hours we were finally able
to attract two Porbeagle sharks but these left as soon almost immediately.
Porbeagles have been known to approach divers (on one occasion aggressively) but
they remain elusive in baited situations.
There are presently no organized Porbeagle Shark diving charters in North
America. In the UK Richard Pierce runs Blue and Porbeagle cage dives.
Other diving locations submitted by