Sharks off the Lisbon Coast
This guide was led by our team of marine biologists. If you’d like to see these species in the wild, check out our Ethical & Licensed Dolphin Watching in Lisbon and keep an eye out for sharks!
During our excursions, we are sometimes surprised by sightings of sharks on the surface of the sea.
Distinguished by the obvious position of their dorsal and caudal fins, which emerge simultaneously, we quickly conclude that we are looking at a shark and, with some calm and luck, we manage to approach gently to identify the species. The most common reaction is for the animal to swim away as soon as it notices our presence, but it really depends on the species and the behaviour being performed. Even if they do, it’s always a fascinating sight.
The waters off Lisbon host more than 47 species of sharks and rays, with the Blue Shark being the most common near the surface, especially in during summer, alongside occasional sightings of the gentle, filter-feeding Basking shark and the Smooth Hammerhead.
While most sharks stay deep, the area around the Lisbon Canyon is very rich on preys and is a crucial nursery for blue sharks.
The sightings at the beaches are extremely rare and pose no threat, as most feed on small fish and are more afraid of humans than the other way around.
Quick Facts
Number of species recorded
3 species were recorded, mostly during our dolphin watching tours.
Most common species
Blue shark, Hammerhead shark and Baskin shark.
Best time of year for observation
The sightings at the surface are more frequent during the summer because of the temperature of the water and its productivity.
Where they are most frequent
Shark sighting occurs mainly in the open sea when the surface of the ocean is very smooth.
Species Gallery
Blue shark
Scientific name: Prionace glauca
Conservation status: Near Threatened (IUCN)
Probability of sighting: Occasional
When we see it: Summer, especially late summer.
ID notes: Bright blue upper body with a white underside; slender body and long snout; very long pectoral fins (often more than twice the length of the first dorsal fin); no interdorsal ridge; no dorsal fin spines.
Why Lisbon?: The open sea off Lisbon is strongly influenced by summer upwelling and the productivity of the Tagus River; the nearby Lisbon Canyon is prey-rich and described as a crucial nursery area for blue sharks.
Did you know?: Blue sharks can have very large litters, and the Lisbon Canyon may help explain why juveniles are sometimes seen closer to shore than expected.
Hammerhead shark
Scientific name: Sphyrna zygaena
Conservation status: Vulnerable (IUCN)
Probability of sighting: Occasional
When we see it: Mostly summer (surface sightings peak in warmer, productive months).
ID notes: Distinctive hammer-like head; the front margin of the head curves back smoothly from the middle (no deep central indentation); olive-to-brown upper body with a white underside.
Why Lisbon?: Seasonal upwelling boosts productivity along the Portuguese coast, concentrating prey in offshore waters near Lisbon.
Did you know?: Hammerheads can use their wide head to help pin prey against the seabed, stunning or immobilising it before biting.
Basking shark
Scientific name: Cetorhinus maximus
Conservation status: Endangered (IUCN)
Probability of sighting: Occasional
When we see it: Late spring–summer (linked to high productivity and plankton availability).
ID notes: Massive grey body; very large triangular dorsal fin; often swims slowly at the surface with its cavernous mouth wide open; five long gill slits; two dorsal fins of different sizes; lunate (crescent-shaped) tail - sometimes dorsal and tail fins are visible together.
Why Lisbon?: Upwelling and canyon-driven productivity can increase zooplankton in offshore waters, attracting this gentle filter-feeder.
Did you know?: Despite its size, the basking shark feeds mainly on zooplankton, especially copepods - tiny crustaceans that graze on phytoplankton.
Biologists’ Notes
Sharks are apex predators and are crucial to the functioning of the marine ecosystem, yet a quarter of all shark and ray species are listed as threatened or endangered on the IUCN Red List. They play an important role in balancing ecosystems by preying on available prey. However, since 1970, the global abundance of Chondrichthys (sharks and rays) has declined by 71%, urging the need to better protect them at an international level.
How We Identify Them
Shark identification is a bit like detective work. Most of the time we don’t see a full animal. We see a dorsal fin cutting the surface, a brief roll, or a shadow beneath the surface. Our golden rule is simple: collect as many characteristics as possible, then combine them into a best-fit identification, including underwater footage.
We look for distinctive features such as unique markings (spots, stripes, scars, fin tips), body colouration, head and snout shape, fin characteristics (size, shape, presence of a ridge), and size and behaviour.
Note: Identification is not always possible – sea conditions and distance matter.
Science Deep‑Dive on the ecology of the group in the region of Lisbon
In Portugal is estimated to have 47 species. The proximity of the Tagus River and its productivity provide nutrients that attract numerous species of fish, ensuring a rich food source. The existence of the Lisbon Canyon intensifies the ocean’s productivity, enriching primary producers that enrich the surrounding area. Sharks are attracted by the availability of food.”
The Portuguese coast becomes attractive to these predators, especially in summer, due to a phenomenon called upwelling. This phenomenon, which involves the rise of water from the depths to the surface, not only cools the water but also brings nutrients from the bottom, leading to a greater concentration of zooplankton that attracts prey and predators.
Feeding and hunting strategies
Sharks are selective predators and opportunistic feeders. Their dentition reflects their feeding habits, and they have a highly developed sense of smell, enabling them to spot prey from several kilometres away.
They eat an amount equivalent to 0.5 to 1% of their body weight per day. They digest slowly, and their meal can be assimilated over 24 hours to 4 days, depending on the species, diet, and water temperature.
Because sharks are predators and opportunistic, they will adapt their diet according to the geographic location, but favorite preys are cephalopods, crustaceans, small fishes and other elasmobranchs. Basking sharks’ main source of food is zooplankton, especially copepods that are microscopic crustaceans that eat phytoplankton. They also eat small shrimp, small fish and fish eggs, all part of the plankton that exists on the column of water.
Sharks employ diverse feeding strategies, including filter-feeding, ambush predation, ram-feeding expanding their mouth wide open and swimming through the water at a continuous pace like the basking shark, opportunist scavenging like the blue shark, taking advantage of available food sources like dead animals and specialized methods like hammerhead sharks which do use their broad heads to pin preys against the bottom, stunning or immobilizing them before attacking.
Ecological role
Sharks are apex predators and crucial to the functioning ofmarine ecosystem. All of them play an important role in maintaining ecosystem balance by predating available prey.
Reproduction and life cycle
Sharks reproduce in three main ways: ovoviviparity, viviparity and oviparity.
Sharks that give birth to live young are either ovoviviparous or viviparous. Their embryos develop in the mother’s uterus before birth. Sharks that lay eggs are oviparous. Most sharks are ovoviviparous, and each embryo receives nutrients from a large yolk sac that is attached to its body while it develops. It is the case of the Basking shark. The blue shark and Smooth hammerhead sharks are viviparous, with a yolk-sac placenta, delivering 4 to 135 pups per litter. The gestation period is between 9 and 12 months. Females mature at five to six years of age and males at four to five.
Courtship is believed to involve male biting, as mature specimens can be accurately sexed by the presence or absence of bite scars. For example, female blue sharks have adapted to the rigorous mating ritual by developing skin three times as thick as male skin.
To improve their pups’ chance of survival, some sharks give birth, or lay their eggs, in nursery areas, where the water is usually warm and shallow, and there’s a good food supply and few predators. Once pups have reached a good size, they go to bigger depths. The Canyon of Lisbon is described as one of these areas, and it may be why we see more juveniles closer to shore.
Behaviours that can be observed
The most common action we see during the tours is feeding behaviours. We see the shark swimming slowly at the surface, with fast movements in turn.
Sharks exhibit a wide range of complex behaviours, including social interactions which can include a dominance behaviour (analyse the size and position of other animals, are inquisitive, swim parallel and/or open the mouth), hunting and foraging methods, reproductive strategies, and communication displays. These behaviours often vary by species and individual personality.
Threats and conservation in the Lisbon region
Overfishing/Bycatch/Climate change/Habitat pollution
Sharks are particularly vulnerable to the threats posed by humans because they reproduce slowly, have long pregnancies, produce few pups and might not reproduce every year. These animals are heavily impacted by overfishing and unregulated activity because their meat, fins, or liver oil are frequently caught accidentally in fisheries targeting other species like tuna and swordfish (Bycatch), and habitat degradation is affecting their prey and their health.
What helps – simple and educational actions
- Raising awareness and promoting stronger management and conservation policies.
- Making conscious consumer choices (avoid shark products like fin, liver oil, cartilage)
- Reduce plastic pollution
- Support shark conservation organisations
- Environmental education
- Advocate for stronger fisheries management and Marine Protected Areas
Our Boat Tours
Our Boat Tours were carefully designed to offer the best nature and cultural experiences in the city.
Dolphin Watching Boat Tour
Birdwatching Boat Tour
Frequent Questions about Sharks
Are there dangerous sharks in Lisbon?
While there are over 40 shark species in Portuguese waters, including potential Great Whites, dangerous encounters near Lisbon are extremely rare, with almost no recorded attacks, making swimming generally safe. Usually, sharks are more afraid of humans than the other way around, but they are wild animals and can be inquisitive, especially when foraging. It is important to always pay attention to local beach flags, especially the blue/purple ones for marine life (including sharks), be aware of strong currents on the Atlantic coast and even more aware when the light of the sun is not good (begin/end of the day), which can also affect sharks’ visibility and coming more close to humans without intention.
Why do sharks attack?
Sharks have been known to attack humans when they are confused or curious, and happen mainly when humans are mistaken as natural prey like seals or turtles, or through curiosity, as they use their mouths to investigate unfamiliar objects, leading to “test bites” that can still cause injury. Other possible factors are territoriality, defence, and higher human presence in their habitats.
Are sharks afraid of dolphins?
Sharks are generally solitary animals, while dolphins are social, which contributes to greater safety and defence. Dolphins’ ability to defend themselves effectively makes them dangerous opponents, causing sharks to be cautious and avoid them. We have had sightings of groups of dolphins passing alongside sharks without any conflict or interest, but with calves, which are more vulnerable, they might also avoid the sharks.
Can we swim with sharks in Lisbon?
Yes, but it is a specific activity which requires a diving license. You can swim with sharks near Lisbon through dedicated dive operators that offer boat dives for viewing blue and mako sharks (we don’t see mako sharks frequently at the surface) in their natural habitat.
These amazing creatures have been facing massive declines in abundance worldwide, mainly due to overfishing and habitat loss. Conservation efforts have been avoinding shark’s massive extinctions, thus more marine and fisheries conservation projects must take action before it is too late.
Sidónio Paes
Marine Biologist
Mini Glossary of Specific Terms
Interdorsal ridge
raised ridge of skin between the 1st and 2nd dorsal fins.
Elasmobranchs
subclass of cartilaginous fish species (class Chondrichthyes) that include sharks, skates, rays, guitarfish, and sawfish.
Cartilaginous
Aa term for the Chondrichthyes, which groups sharks, rays, skates, sawfish, and chimaeras. All these vertebrates share common characteristics: jaws, paired fins, gills, and a skeleton made of cartilage rather than bone.
IUCN Red List
The IUCN Red List is a critical indicator of the health of the world’s biodiversity. Far more than a list of species and their status, it is a powerful tool to inform and catalyse action for biodiversity conservation and policy change, critical to protecting the natural resources we need to survive. It provides information on range, population size, habitat and ecology, use and/or trade, threats, and conservation actions to inform necessary conservation decisions.
Scientific References
This guide is supported by scientific literature, field research, and the SeaEO team’s know-how. Below you can explore the main sources used.
Estupiñán-Montaño, C., Cedeño-Figueroa, L., Estupiñán-Ortiz, J.F., Galván-Magaña, F., Sandoval-Londoño, A., Castañeda-Suarez, D., & Polo-Silva, C.J. (2019). “Feeding habits and trophic level of the smooth hammerhead shark, Sphyrna zygaena (Carcharhiniformes: Sphyrnidae), off Ecuador”. Journal of the Marine Biological Association of the United Kingdom, 99 (4), 673-682.
“A guide for NSW commercial fishers” (Online). NSW Department of primary industries.
Correia, J.P.S. 2009. Pesca comercial de tubarões e raias em Portugal. Dissertação de Doutoramento em Biologia. Universidade de Aveiro. 402 pp.
IUCN. The IUCN Red List of Threatened Species. Version 2025 (IUCN, 2025).
Olson, Danielle. 2022 “The Massive Filter Feeding Shark You Ought to Know” (online). Ocean Find your Blue. Accessed on: January 15, 2026
Pacoureau, N.; Rigby, C.; Kyne, P.; Sherley. R.; Winker, H., et al. 2021. Half a century of global decline in oceanic sharks and rays. Nature: 589, pp. 567-571
“Shark reproduction”. Shark trust. Accessed on: January 15, 2026
Vásquez, Daniela, 2024 (Online). “Tubarões à vista em Portugal? Estão à procura de alimento, não de banhistas”. Jornal Publico. Accessed on: January 15, 2026