The Porpoise Detectives

How Citizen Scientists Are Unlocking Shetland's Marine Mysteries

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The Silent Sea: A Mystery in the Waves

Imagine staring out at the cold, choppy waters of Shetland, binoculars in hand, waiting for a glimpse of one of the UK's most elusive marine mammals—the harbour porpoise.

97% Decrease

Alarming decline in harbour porpoise sightings around Bardsey Island, a former stronghold for these animals 1 .

Community Power

Revolutionary approach using citizen scientists to fill critical knowledge gaps in Shetland 2 4 .

Why Porpoises Matter: More Than Just a Pretty Face

Harbour porpoises are often called the "sentinels of the sea." As top predators in their ecosystem, their presence—or absence—offers crucial insights into the overall health of our oceans 3 .

Food Scarcity

Diminishing food sources due to overfishing and changing sea temperatures 1 .

Ocean Noise

Constant hum of boat traffic disrupting their ability to navigate and find food using echolocation 1 .

Fishing Bycatch

Constant danger of becoming entangled in fishing gear 3 6 .

The Shetland Porpoise Project: A Community's Watchful Eyes

The Shetland Porpoise Survey represents an innovative approach to marine conservation. Established in collaboration with Whale and Dolphin Conservation, the project has created dedicated "Shorewatch" sites at key locations around Shetland.

Standardized Watches

Volunteers station themselves at predetermined sites and conduct timed watches, scanning the sea with binoculars.

Data Collection

For every marine mammal sighting, they record the species, number of individuals, distance from shore, and observed behaviors.

Digital Archives

The data is submitted to centralized databases where it is used by NatureScot and Shetland UHI to update Regional Marine Plans and identify areas critical for protection 4 .

Year-Round Monitoring

Addresses a major limitation of traditional marine mammal surveys: the scarcity of data during winter months and from remote coastal areas.

Advanced Technology

Incorporating experienced drone pilots to capture aerial footage of porpoise groups for accurate counts and behavioral observation 4 .

The Science of Listening: Eavesdropping on Porpoise Conversations

While citizen scientists scan the surface, another sophisticated tool is listening beneath the waves. Passive acoustic monitoring using specialized underwater microphones called CPODs has revolutionized our ability to detect harbour porpoises, even when they don't surface .

Echolocation

Harbour porpoises rely on echolocation for navigating dark waters, locating prey, and communicating.

Terminal Buzz

Characteristic sound that signals a successful catch, providing a window into their underwater lives .

CPOD Detection Ranges
Detection Type Effective Range Monitoring Diameter
Raw Signal ~200 meters ~400 meters
Classified Clicks 72 meters 144 meters
Raw Signal Detection 566m (max)
Classified Click Detection 72m (effective)

The Bigger Picture: What Strandings and Stress Tell Us

The Scottish Marine Animal Stranding Scheme (SMASS) has collected 30 years of data from beached cetaceans, providing another critical piece of the puzzle. Their research reveals troubling trends: all cetacean groups have shown significant increases in annual stranding rates over the past three decades 3 .

Cetacean Strandings in Scotland (1992-2022)
Species Group Number of Strandings Percentage Primary Season
Harbour Porpoises 2,676 52% Spring (March)
Pelagic Dolphins 1,217 24% Summer (July-August)
Common Dolphins 494 10% Winter (February)
Baleen Whales 479 9% Summer (July-August)
Deep Divers 281 5% Autumn/Winter (Oct-Feb)
Stress Research

Groundbreaking study developed methods to extract cortisol from harbour porpoise skin, creating a potential tool for assessing chronic stress levels in populations 5 .

Minimally Invasive Technique

Uses small skin plugs or epidermal scrapes to revolutionize how we monitor porpoise health in the wild.

The Researcher's Toolkit: Porpoise Monitoring Essentials

Tool Function Application in Shetland
CPODs (Cetacean PODs) Underwater hydrophones that detect and classify porpoise echolocation clicks Deployed at key sites to monitor porpoise presence and foraging behavior 24/7
Binoculars & Survey Kits Standardized equipment for visual monitoring Used by citizen scientists at Shorewatch sites for consistent data collection 4
Acoustic Playback Systems Equipment to broadcast artificial porpoise clicks Used in experiments to determine CPOD detection ranges and improve data accuracy 7
Digital Photo-ID Databases Collections of dorsal fin images for individual identification Helps track individual porpoises over time, providing data on movements and population 6
Skin Sample Analysis Laboratory techniques to measure stress hormones Extracting cortisol from skin samples to assess physiological health of populations 5
Drone Technology Aerial photography for population counts Provides accurate counts of porpoise aggregations and documents presence of calves 4

A Future for Porpoises: From Data to Protection

The integrated efforts in Shetland—combining community sightings, acoustic monitoring, and stranding analysis—are producing tangible conservation outcomes.

Marine Protection

Data collected directly informs marine spatial planning, helping identify Marine Protected Areas 4 6 .

Global Impact

Similar citizen science initiatives have proven their worth globally, accurately predicting distribution patterns 8 .

Community Partnership

Protecting these enigmatic creatures depends on powerful partnership between science and community.

"The work of the Shetland Porpoise Survey demonstrates that you don't need a PhD to contribute to meaningful science; you just need patience, passion, and a watchful eye on the sea."

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