Crab Watch

Crab Watch App (Android)

MACUMBA Factsheet

Crab Watch App (Apple)


What is Crab Watch?

Crab Watch is a citizen science initiative developed as part of the Sea Change Project. The initiative explores how citizen science can be used as a tool for increasing Ocean Literacy, as well as collecting scientific data. Crab Watch will generate data to enhance our knowledge of the changing distribution of native and non-native crabs, as well as information to support environmental management.

The goals of Crab watch are:

1) To raise awareness of the changing distribution of native and non-native crabs
2) To use citizen science to generate valuable scientific data that is freely accessible
3) To encourage people to explore and engage with their oceans

Why is it important?

Crabs can be found around Europe in all marine and some freshwater habitats. They have great commercial and cultural significance in many countries, and are popular creatures for people to search for when by the coast. Crabs are easily impacted by the activities of humans, including warming seas, the introduction of invasive species and overexploitation, this makes them an ideal subject to help demonstrate how our Oceans are changing and what the impacts are. Several species of non-native crab, including the Asian shore crab (Hemigrapsus sanguineus) and Chinese mitten crab (Eriochier sinensis) are present in multiple European countries. There is evidence to suggest that the Asian shore crab (H. sanguineus) in particular is likely to negatively impact populations of the native European shore crab (Carcinus maenas).

By getting people out visiting their coastline and interacting with marine creatures in a meaningful way, the scheme will encourage people to think positively about their ocean and to become sustainable Ocean advocates!

Crab watch 3  paper plate crab  Crab watch 4  Hemigrapsus sanguineus FrontView

How will we collect the data?

The coastlines of Europe range from the negligible tides and sandy shores of the Mediterranean to some of the highest tidal ranges in the world on the rocky Atlantic coasts. To account for this variation, the scheme includes 3 key methods, each designed to maximise engagement and cater for people with different levels of interest and in different geographical areas.

Protocol 1: Ad-hoc recording of crabs using a specially developed App to record crabs as you see them. 
Protocol 2: Crab fishing from a structure using nets and bait to catch and record hiding crabs.
Protocol 3: Exploratory shore search for any intertidal upper to lower shore where you might find crabs.

By establishing a scheme to record and report crab distribution and an associated team of Crab Watchers around Europe, it is hoped that new crab arrivals will be quickly detected, allowing for appropriate management action.

Find out More

If you would like to know more about the project or about how you can get involved please email us at:

Download the App Here for Android or iOS

Join the conversation on Twitter using #Crabwatch




  • Phone

    Jon Parr
    Sea Change Coordinator
    +44(0)1752 426479

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  • Email

    Jon Parr
    Sea Change Coordinator

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  • Address

    Marine Biological Association
    Citadel Hill,  Plymouth,
    PL1 2PB, United Kingdom

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