From land, it’s very tricky to see porpoises, even though they often spend time very close to shore. But from a boat and with an understanding of their feeding patterns alongside the tidal movements and bird behaviour we have many close-up encounters. They are smaller then their dolphin cousins, measuring about 1.8 to 2 meters as fully grown females, which are slightly larger than the males. They have a dark grey back and a much lighter underside. Their dorsal fin is short and stubby, and they have a short snout that contributes to their beautiful smile. They move fast and spend more time underwater between breaths than the common dolphin. Their movements are often faster than dolphins as they spend much more time on the hunt and don’t breach as often. However, they do jump when breeding.

When spotting them, it’s important to listen for their tell-tale puffing sound as they take air. Due to their elusive nature, scientists often use hydrophones to study them, as they have a higher frequency sound range than dolphins.

There are seven known species of porpoises; however, it is the Harbour porpoise that can be found in the UK and many areas around the North Atlantic and Pacific Oceans. They venture up into the northern circle and as far south as North Africa and on both the east and west coasts. You can find them in many areas of UK waters; however, due to a history of persecution, their numbers have diminished greatly. They are still considered the UK’s most abundant species of cetacean. Some estimates suggest that half of the world population of porpoises may be found in UK waters, but it is very hard to get accurate numbers on any marine life, so this can be misleading. Due to their behavior and the sea conditions of the North Atlantic, they certainly are not the most sighted.

Throughout the UK, they are considered to live in small groups; however, there are places where their numbers are still very strong. The far west of Cornwall is one of these areas, with Lands End and Mounts Bay seeing booming numbers during the summer months. They are named Harbour porpoises because they are often found close to bays, estuaries, and even harbors. Although, in areas where we operate, we tend to find them on tidal fronts or areas with dramatic topography.

Harbour porpoises primarily eat small schooling fish, such as herring, pilchard, and sand eels. They also consume squid, octopus, and shellfish. Due to the cold subarctic waters that porpoises call home, they have to burn a lot of energy to keep warm, which means they have a very high metabolism. They are constantly on the hunt day and night. Each day, a harbour porpoise has to eat about 10% of its body weight, which translates to approximately 7 to 8 kg of fish daily. A large sand eel weighs around 10 grams, so that’s about 800 fish each day!

They use echolocation to track down their prey and are extremely fast, capable of swimming at about 30 km/h over short distances and diving to depths of 400 meters. Their very nimble mouths allow them to turn prey fish so they can swallow them whole and headfirst, preventing any bones from getting stuck in their throat. Their teeth are spade-shaped, which they use to munch on shellfish. They catch over 90% of the fish they pursue, compared to the 48% success rate of a great white shark, making them formidable predators—if you happen to be a sand eel. Like dolphins they work together to ball up shoals of fish and will pin them against the surface or up against faster flowing water. In what we call a bate ball.

Porpoises are masters of stealth; we may be observing them one moment, and then they simply disappear. They often stay hidden from us, especially when we are among large numbers. Remarkably, they have evolved to communicate and navigate using sound frequencies higher than those of killer whales and dolphins. This adaptation helps them remain hidden, while dolphins may often vocalize off their catches. More importantly, it allows porpoises to stay under the radar of killer whales so they don’t become a tasty snack

As with so many of our marine mammals, human conflict is a dark tale. They were once known as puffing sea pigs, and the name porpoise is derived from the Latin word *porcus* meaning “pig.” This is not just because they make a beautiful chuffing sound when they take a breath but also because they were once a source of food. Due to religious reasons in the 14th century, pork was taken off the menu, which led to the overfishing of porpoises, making up a large part of the coastal communities’ diet. In the 15th century, their numbers crashed until it was made sinful by the church to eat them unless you were royalty or a man of the cloth. It’s sad that Henry the Eighth was particularly partial to porpoise steak.

Numbers largely recovered until the industrialization of whaling impacted our seas. The porpoise, rich in oils, was plundered to fuel the fires with which whalers extracted oils from whale carcasses. It doesn’t get much darker than that. Pollution followed next, with PCBs used on farmland as pesticides washing from our fields down our streams and rivers, causing incredible damage to many marine species. This made many marine mammals infertile and caused birth defects in others. The porpoise was particularly hard hit due to their close proximity to the coast. PCBs were banned in the ’80s, but today’s pressures come from environmental change, overfishing, bycatch, and ghost nets, as well as noise pollution, plastic, and other chemical waste products. Unbelievably they are still haunted in some areas, Will we ever learn there is estimated to be only 700,000 left world wide.