2.1.9 Pilot Whales (Globicephala spp.)
Pilot whales comprise two separate species, the long-finned pilot whale
(Globicephala melas) and the short-finned pilot whale (Globicephala
macrorhynchus). Male pilot whales can reach lengths up to 6 m while females are
significantly smaller. Long-finned and short-finned pilot whales are difficult to
distinguish by the way they look, but close examination allows a differentiation
based on flipper length, skull shape or number of teeth.
The habitat of long-finned pilot whales are the colder temperate waters of the
North Atlantic and the Southern Ocean. The two subgroups are genetically different
and do not interact. Short-finned pilot whales can be found in tropical and subtropical waters and in the waters of the North Pacific. The short-finned pilot whales of
northern and southern Japan, which are geographically separated, show differences
in morphology, but the state of research assigns them both the same taxonomic
name, G. macrorhynus.
Pilot whales have been extensively hunted all over the world. While in the past,
drive fisheries have existed in Newfoundland, Norway, the Orkney Islands,
Hebrides, and Iceland, contemporary drives are only conducted in the Faroe Islands
and Japan. Although these hunts may take up to several hundred whales per year,
there is no indication of population decline. What has become clear, however, is that
pilot whales consumed by humans hold high levels of mercury. While in Japan these
levels are not considered dangerous for humans, in the Faroe Islands the Faroese are
advised to merely consume a limited amount of pilot whale per year to avoid
negative effects of mercury. One of the other direct major threats to pilot whales is
by-catch in different types of fisheries. It is unclear how large the numbers of pilot
whales taken as by-catch are since only few countries are required to note pilot whale
mortalities in fisheries.
24
Both short- and long-finned pilot whales are listed as ‘least concern’ although
their population trend is unknown.
2.2
Seals
Seals or pinnipeds (Pinnipedia) are a group of marine mammals comprising around
33 different species. Pinnipeds are subdivided into three subgroups: earless or true
seals (Phocidae), eared or fur seals and sea lions (Otariidae), and the walrus
(Odobenidae). Earless seals with 18 distinct species constitute the larges group of
seals, followed by sea lions with 14 species. The walrus is the only member of the
genus Odobenidae. Seals constitute around one third of all marine mammal species
in the world.
Contrary to cetaceans, pinniped species have adapted to the marine, as well as the
terrestrial, environment and their habitat can be found in both. This means that they
24 Olson (2008), pp. 247–252.
2.2 Seals
25
Pilot whales comprise two separate species, the long-finned pilot whale
(Globicephala melas) and the short-finned pilot whale (Globicephala
macrorhynchus). Male pilot whales can reach lengths up to 6 m while females are
significantly smaller. Long-finned and short-finned pilot whales are difficult to
distinguish by the way they look, but close examination allows a differentiation
based on flipper length, skull shape or number of teeth.
The habitat of long-finned pilot whales are the colder temperate waters of the
North Atlantic and the Southern Ocean. The two subgroups are genetically different
and do not interact. Short-finned pilot whales can be found in tropical and subtropical waters and in the waters of the North Pacific. The short-finned pilot whales of
northern and southern Japan, which are geographically separated, show differences
in morphology, but the state of research assigns them both the same taxonomic
name, G. macrorhynus.
Pilot whales have been extensively hunted all over the world. While in the past,
drive fisheries have existed in Newfoundland, Norway, the Orkney Islands,
Hebrides, and Iceland, contemporary drives are only conducted in the Faroe Islands
and Japan. Although these hunts may take up to several hundred whales per year,
there is no indication of population decline. What has become clear, however, is that
pilot whales consumed by humans hold high levels of mercury. While in Japan these
levels are not considered dangerous for humans, in the Faroe Islands the Faroese are
advised to merely consume a limited amount of pilot whale per year to avoid
negative effects of mercury. One of the other direct major threats to pilot whales is
by-catch in different types of fisheries. It is unclear how large the numbers of pilot
whales taken as by-catch are since only few countries are required to note pilot whale
mortalities in fisheries.
24
Both short- and long-finned pilot whales are listed as ‘least concern’ although
their population trend is unknown.
2.2
Seals
Seals or pinnipeds (Pinnipedia) are a group of marine mammals comprising around
33 different species. Pinnipeds are subdivided into three subgroups: earless or true
seals (Phocidae), eared or fur seals and sea lions (Otariidae), and the walrus
(Odobenidae). Earless seals with 18 distinct species constitute the larges group of
seals, followed by sea lions with 14 species. The walrus is the only member of the
genus Odobenidae. Seals constitute around one third of all marine mammal species
in the world.
Contrary to cetaceans, pinniped species have adapted to the marine, as well as the
terrestrial, environment and their habitat can be found in both. This means that they
24 Olson (2008), pp. 247–252.
2.2 Seals
25