Issue #3. FOTW: Northern Pike (Esox lucius), an army of herring, and a life aquatic
Joe Huddart, PhD ??
?? Aquatic ecologist and eDNA Town Crier at NatureMetrics - if not now, when?
We welcome in Q2 with a formidable feast: Fish of the Week is a fish with a terrible reputation- the northern pike, school of thought: semantics and the collective nouns for fish and fishes, wrapping up with a look at the fintastic life and recent interview by Shoal Conservation with Professor Roberto Reis, finishing with Fish On- some tails from the last week, also the latest on Thames water- is nationalisation finally on the cards?.....
FOTW- the northern pike (Esox lucius)
” The mighty luce or pike is taken to be the tyrant, as the salmon is the king of the fresh waters”
-- Izzac Walton, The Compleat Angler, 1653
Is there a freshwater fish in the Northern Hemisphere with a more fearsome reputation than the pike (Esox lucius)? We don't think so; the pike, historically called 'pike-fish', has a distinct profile separating it from nearly all other species where it is found. Namely, the pointed snout, named after the sharp-pointed weapon of medieval times, the pike.
Pike, three inches long, perfect
Pike in all parts, green tigering the gold.
Killers from the egg: the malevolent aged grin.
They dance on the surface among the flies.
Or move, stunned by their own grandeur,
Over a bed of emerald, silhouette
Of submarine delicacy and horror.
A hundred feet long in their world.
The opening of Pike, read the rest here, by Ted Hughes, a genius poet but terrible man. He raised some pike in a tank from juveniles and watched as they proceeded to eat each other as they grew.
A long body built like a torpedo and when open, a huge, bristling mouth packed with very fine, very sharp teeth. There is something Jurassic about pike. It is the freshwater analogue of a barracuda (Great barracuda). Yet, despite hunting in similar short bursts and being a ferocious predator, these fish are only very distant cousins. A classic case of convergent evolution; where looks can be deceiving and imply genetic relatedness when in reality they have evolved independently. It most often occurs between species occupying a similar niche that selects for similar adaptations.
Many people know of the pike and its reputation before ever (if ever) setting eyes on one in real life. Just like their name, they are famed for being aggressive and have been known to bite at swimmers. Some even recommend to avoid wearing jewellery when swimming in waters with large pike as they might mistake the flashing and glinting for small fish. Walt Disney immortalised its ferocity in The Sword and the Stone (below) and they also feature in Russian folklore, albeit more benevolently in At the Pike's Behest or more ominously the World War II Russian navy's Shchuka-class submarine - Wikipedia.
On that note, do not mistake the Russian word for northern pike “shchuka” with the Russian word for a female dog (and wider insults) "suka", or your conversation might take a nasty turn.
Ecology
Habitat: Northern by name, northern by distribution. Northern pike have a freshwater range that circumferences the Northern Hemisphere. In part because they are incredibly versatile. Perhaps the only place they do not thrive is in upland, fast-flowing, spatey rivers. They can occupy all depths of lakes and thrive in reedy, slower rivers. Their range also covers the Arctic Circle, so they can tolerate thick ice cover. River pike are usually a little skinnier than lake pike, maybe a combination of food availability and swimming against currents. Reservoirs and lakes are particularly good for harbouring monster resident pike, just check out the size of this record-breaking pike landed on lake Chew in the UK.
Fish Fact: Pike were historically present in the Baltic Sea in large numbers, with the population displaying tolerance to the brackish waters. However, they need to migrate back into freshwaters to spawn, what we call anadromous, like last week's sea trout. However, these anadromous Baltic pike are in decline, with the loss of coastal freshwater spawning habitat, climate change and pollution thought to have led to dramatic declines.
Spawning: takes place in late spring coinciding with the first macrophytes (freshwater plants) starting to grow. These amorous encounters can be a very scrappy affair, with a lot of reed movement and splashing, eggs stick to plants before hatching. I know of an experimental removal of pike in Sweden that dynamited lake reed beds at spawning time to wipe out the population.
A small pike caught on a lure in March 2024, and a very happy Nat Browning .
Diet: It is an ambush predator, capable of taking fish greater than half its size, ducklings (viewer be warned, not pleasant), and also a renowned cannibal. Pike have been found dead after trying to eat other pike their size. As juveniles they prey on invertebrates and fry. It moves quickly in short bursts, but also tires fast. It therefore relies on stalking to get within range.
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Back to school, or is it shoal?
In case you missed it, in Issue #1 I explained the difference between fish singular 'fish' and plurals 'fishes' (different species) or 'fish'. But what is the collective noun for fish? Is that a shoal of fish or a school of fish? We can use the term 'aggregation', but that is a little bland.
A shoal of fish could be a mixture of species and a group of fish of different sizes. This isn't a random accumulation, there is an awareness of each other and choosing to aggregate. They might individually be moving in different directions doing their own thing, but they are sticking together. Typically this behaviour is to avoid predators.
whereas,
A school of fish is the more beautiful, synchronised and coordinated movement of fish of the same species (and usually size) in a common direction. Think David Attenborough's giant Blue Planet baitballs.
This coordination between individuals in a school follows some simple rules: "Each fish maintains a “zone of repulsion” with its neighbours where a fish automatically turns away from a neighbour in order to avoid collision. Outside that zone is the “zone of orientation” where each fish attempts to match its neighbours", read more here
Some species of fish have their own collective nouns, for instance:
If you know all this already, we'd be guilty of 'piscem natare doces' the Latin proverb for 'teaching fish to swim'
A life of fish
If you do not follow Shoal Conservation , you are missing out. These guys are on the front line doing some incredible work bringing back threatened freshwater fish from the brink of extinction around the world and spreading the word. Expect a lot more Shoal action.
One story that caught us hook line and sinker was their interview with Brazilian ichthyologist, professor and Curator of Fishes at the Pontifical Catholic University of Rio Grande do Sul, Roberto Esser dos Reis.
With the help of his students and collaborators, he has described 151 new taxa (including 139 new species), 17 new genera, and one new subfamily of fish. Check out his excellent interview here.
Most of his work focuses on the plecos, a docile but diverse group of catfishes we commonly sea sucking the glass in aquariums. Here's a look at them.
In 2022 alone, while the rest of us were learning how to write again after COVID-19, he discovered 8 species! Check out the Shoal Conservation 2022 new species report.
Quote of the week: "What moves me is revealing undetected biodiversity and studying their phylogenetic relationships. Discovering and describing new species completes our knowledge about the diversity of life on Earth and allows for adequate conservation planning."
What we like about this is that they are freshwater fish- hammering home that we are still in an era of species discovery and freshwater fishes are crazy diverse. He reckons there are 36,400 species of fishes described with many thousands more to be discovered.
Fish on- best fish headlines of the week
Tight lines