The World's Forgotten Fishes - 14

© Tim Watts

2. DAZZLING DIVERSITY

Elvers

THE EUROPEAN EEL:
MYSTERIOUS MIGRATORY
MARVELS
There's a lot that we still don't know
about European eels, Anguilla anguilla
(and its 15 anguillid sister-species
around the world, for that matter).
Nobody really understands how or
why after 10 years or more of quiet
freshwater living, European eels
suddenly swim as far as 8,000km to
Salmonids
spawn in the north Atlantic's remote
Sargasso Sea - and their early life
history is equally mysterious. But we
do know that eel larvae drift towards
Europe in enormous numbers and
the tiny 'glass eels', which eventually
arrive to make their homes in our
coasts, estuaries, rivers and lakes,
have historically thrived across the
continent. In the 19th century, eels
made up about a third of the total
European freshwater catch by value.
Today, though, they're listed as
Critically Endangered by IUCN. In
1980, their numbers began to fall by
about 15 per cent each year, until by
2010 glass eels were arriving in Europe
in just 1 per cent of their historical
numbers. While overfishing played
a part in the decline of European
eels, they face a range of threats
today, including river barriers that
block their migration, hydropower
dams whose turbines slice and dice
them, poaching for the illegal wildlife
trade (eels constitutes the largest
illegal wildlife trade out of Europe),
pollution, diseases and parasites, and
climate change, which may already be
impacting their journey to and from
their spawning grounds.

The World's Forgotten Fishes page 14

Freshwaters are also home to living
lineages of truly ancient animals,
such as lampreys, which along with
hagfishes, are the only surviving
species of jawless fishes - the very
first type of fish to appear on Earth
around 530 million years ago. Around
400 million years ago, fish gave
rise to tetrapods, a group of related
four-limbed animals that includes
today's amphibians, reptiles, birds
and mammals. Today the birchir is
the only living relative of this ancient
type of fish. Lungfishes are another
ancient group that evolved around
380 million years ago. Contemporary
to the dinosaurs are the gar, sturgeon,
paddlefish and bowfin, which all
evolved around 120-130 million years
ago. Meanwhile, in 2020, a 'new'
species of freshwater fish belonging to
a new family - the dragon snakeheads
- was discovered10 in India with
Gonwanan lineage dating back 120
million years.
This extraordinary diversity
churns out a myriad of weird and
wonderful names. So along with the
leaffishes and lungfishes, there are
ricefishes, rainbowfishes, sunfishes,
mosquitofishes, toadfishes, halfbeaks, galaxiids, noodlefishes and
mooneyes. And many more.
The greatest diversity of freshwater
fishes is found in the tropics, with
the Amazon leading the way with
over 2400 known species11. But
there is a long way to go until we

Figure 3: Almost 90% of freshwater fish species
are found in eight orders: carps, minnows and
loaches (Cypriniformes), catfishes (Siluriformes),
characins and tetras (Characiformes), cichlids
(Cichliformes), toothcarps and killifishes
(Cyprinodontiformes), gobies (Gobiiformes),
perch-like fishes (Perciformes), and bettas and
gouramis (Anabantiformes).

Perch-like fishes 574
270 Bettas & Gouramis

Gobies 954

4701 Carps,
Minnows & Loaches
Toothcarps & Killfishes 1417

Cichlids 1731

Characins &Tetras 2290

3822 Catfishes
The World's Forgotten Fishes

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