Goose barnacles, also known as stalked barnacles, are crustaceans that live attached to hard surfaces underwater. They are found in oceans all around the world, but are most abundant in cooler, rocky coastal areas. Understanding where goose barnacles are found can help people locate them for food or scientific study.
What are goose barnacles?
Goose barnacles, or pedunculata barnacles, are a type of filter-feeding crustacean that live attached to surfaces underwater. They have a fleshy stalk that attaches their shell to rocks, ships, driftwood, piers and other hard surfaces. Goose barnacles feed by extending feathery legs from their shell to catch plankton floating by in ocean currents.
There are over 1,000 species of stalked barnacles around the world. The most common is the gooseneck barnacle (Pollicipes pollicipes), which is found along the Atlantic coasts of Europe and Africa. Other common species include the thatched barnacle (Mitella pollicipes) and the finger barnacle (Capitulum mitella). Barnacles are related to crabs and lobsters.
Where are goose barnacles found?
Goose barnacles occupy every ocean in the world. However, they tend to thrive in certain habitats:
- Rocky shores – Goose barnacles settle on hard, rocky surfaces like cliffs, breakwaters and boulders along coastlines. Rocky shores provide anchoring points and allow gooseneck barnacles to feed in nutrient-rich waters.
- Pier pilings – Manmade structures in the intertidal zone like piers, docks and jetties often become encrusted with goose barnacles. The pilings provide a convenient hard surface.
- Ship hulls – Goose barnacles commonly grow on the underside of ships, attaching their stalks to the hull. Their larvae are spread to new areas as ships travel.
- Driftwood – Sunken, waterlogged wood offers an attachment spot for goose barnacles in some habitats.
Goose barnacles tend to thrive in cooler water temperatures between 50-70°F (10-21°C). This makes them abundant in regions like:
- Northern Atlantic Coast – Europe, Canada, Maine
- Pacific Coast – California to Alaska
- Southwestern coasts of South America – Chile, Argentina
- Southern Australia and New Zealand
They can survive in tropical waters but are less common where temperatures exceed 75°F (24°C) for long periods.
Intertidal zone distribution
Within an ocean habitat, goose barnacles distribute themselves vertically according to tidal zones:
- High intertidal zone – Goose barnacles exposed to air during low tides. Less submerged time limits food availability.
- Middle intertidal zone – Goose barnacles spend equal time submerged and exposed. Allows for ample feeding.
- Low intertidal zone – Goose barnacles rarely exposed by tides. Submerged most of the time but may be damaged by wave action.
Middle intertidal zones tend to support the highest densities of goose barnacles as they balance submersion with wave exposure. The lowest zones near constant water may have fewer barnacles.
Depth distributions
Vertically in the water column, goose barnacles live at varying depths:
- Shallow subtidal – Attached to pier pilings, jetties and other structures in less than 30 feet of water.
- Continental shelf – On rocky reefs, shipwrecks, oil platforms down to around 300 feet depth.
- Bathyal zone – Scattered barnacles on cliffs and canyons down to 2000 meters.
The highest densities occur in shallow, nearshore waters where food availability and attachment sites are abundant. Only sparse, patchy distributions exist in the deep sea.
Locating goose barnacles
People wishing to locate goose barnacles for harvesting or research purposes can improve their chances by knowing where to look. Useful tactics include:
- Survey rocky shores at low tide – Scan cliff faces, boulders and other hard surfaces in the intertidal zone for clusters of barnacles.
- Check pier pilings – Wander piers at extreme low tide and look for goose barnacles encrusting the pillars.
- Inspect floating docks – Pole or lift docks out of the water to inspect their undersides for attached barnacles.
- Note debris on beaches – Check driftwood, buoys and other floating debris washed up onshore for attached goose barnacles.
- Talk to fishermen – Inquire with local fishermen about where they find heavy fouling by goose barnacles on their gear.
It often takes exploring various sites to locate ideal habitat. Prime locations may be kept secret by commercial harvesters. Be sure to obtain any necessary permits before collecting goose barnacles.
When to search
The best timing for finding goose barnacles depends on the tidal cycle:
- Spring low tides – The lowest tides of the month expose more of the intertidal zone for surveying potential goose barnacle habitat.
- Neap tides – Moderate low tides may be optimal, as very low spring tides may expose barnacles to overheating and desiccation stress.
- Mating season – Goose barnacles aggregate to mate from late winter through summer, making them easier to spot.
- Molting season – After mating, barnacles molt their shells and are more likely to detach, so numbers peak in autumn.
Ideally, aim to search for goose barnacles at moderate low tides during peak mating and molting times from spring through fall. This boosts the odds of locating productive habitat.
Seafood harvesting
Knowing where to find goose barnacles allows for their regulated harvest as a seafood item. Barnacles are a pricey delicacy in Spain, Portugal and other countries. Strict limits are placed on the size and quantity of barnacles that licensed commercial fishermen can collect. There may also be restrictions on the harvesting tools and methods used.
Iberian gooseneck barnacles (Pollicipes pollicipes) from Spain and Portugal are particularly prized. A single pound of large barnacles can retail for over $100. Prices have led to overharvesting concerns in some areas like the Galicia region of Spain.
Sustainable harvesting is encouraged, along with the establishment of barnacle harvest exclusion zones and protected reserves. following goose barnacle abundance through surveys also helps set appropriate catch limits by region.
Research value
Understanding the distribution and habitat preferences of goose barnacles has scientific importance as well. Some key research applications include:
- Monitoring populations – Tracking goose barnacle density in different zones and habitats helps assess overall population trends.
- Studying reproduction – The timing and location of barnacle mating and molting events can be documented.
- Researching adaptions – Scientists examine how barnacle anatomy and biology adapt to the pressures of specific tidal environments.
- Assessing water quality – The health and growth rates of barnacle populations indicates local water quality conditions.
Locating goose barnacles allows ecologists to study the barnacles themselves and use them as bioindicators for monitoring environmental conditions. Permanent monitoring sites may be established within key habitats.
Threats to habitat
Goose barnacles depend on specific habitat features to thrive. Some human activities threaten the habitats they rely on:
- Shoreline development – Building harbors, seawalls and other structures can eliminate rocky intertidal areas.
- Pollution – Contaminants from sewage, agriculture and industry can degrade water quality.
- Invasive species – Nonnative species competing for space can displace native goose barnacles.
- Climate change – Ocean warming and acidification impact growth and reproduction.
Conservation efforts aimed at protecting coastal ecosystems can help preserve vital goose barnacle habitat. This includes designating protected marine reserves in regions of prime habitat.
Conclusion
Goose barnacles inhabit rocky shores and structures worldwide, with especially abundant populations in cool, food-rich waters. The intertidal zone along coastal cliffs, breakwaters, piers and pilings offer prime goose barnacle habitat. Knowing where to find goose barnacles makes it possible to sustainably harvest them as seafood, and study their ecology for conservation purposes. Protecting vulnerable nearshore habitats helps ensure thriving goose barnacle populations into the future.