On the surface, this is a straightforward book of fish facts. On another level, it’s a story about gorging and slurping, about human nature, about waste, about greed. There’s a bit near the end about how the hagfish (or “bloody snot eel”, as Dad would call it) will patiently rasp itself inside softening corpses on the seafloor. If that doesn’t work, the hagfish will force its body against the rotting ribcage, or belly, or whatever, writhing until it gives way. Gross, but not as gross as the human appetite. The reading experience reminded me of being a kid and watching, horrified, as my uncle ate a whole bucket of prawns.

Robert Vennell fillets his beautiful book into five sections, from fresh water and shorelines to the deep seas. Within each he covers just a handful of creatures. Bold choice, quality over quantity—and undoubtedly the best one. Each chapter is deep and rich. Māori perspectives, stories and histories are centred. Taxonomy and etymology, aptly, are broken out into little boxes. Vivid illustrations (some of which are reproduced here) flicker and dart throughout.

Vennell is very good at writing about abundance. He conjures an Aotearoa where dogs lap up whitebait from rivers; the piper fish swim in shoals three kilometres long; kids walking home from school stop off at the rockpools, picking up a crayfish for each family member.

His language is plain: eels are “gigantic tubes of meat”; pāua “thick, meaty chunks of protein”. But the numbers are obscene. Twenty thousand eels served at a feast in 1838. Eighteen million crayfish tails shipped to the US in 1949 (the tails were often snapped off, the crays dumped at sea). One weekend, 50,000 people turned up at a beach near Dargaville to dig for toheroa. They took home more than a million shellfish, leaving what they couldn’t eat at the tip. There are small numbers, equally grotesque: Vennell writes of a Dunedin hotel serving up flounder less than five centimetres long, and of blue cod for sale, weighing less than 100 grams.

There’s a chapter about upokororo, the New Zealand grayling, last seen in 1923. Māori had stealthy methods of catching these particularly skittish fish. Pākehā simply dynamited the rivers, “causing entire shoals to float to the surface, where they could be scooped up and collected”. How on Earth have we managed to drive only one fish extinct? The true secret of the sea is that we ate it all.