Snorkel Surveys of the Marine Environment – Methodology Guide

Pilot areas
Marine Protected Area (MPA) managers
MPA management
Bio-constructors, biodiversity, conservation, fish, habitats, Marine Protected Area, monitoring, MPA, MPA managemen, Posidonia oceanica, protocol, snorkel, snorkel fins, species


MPA managers must find the right balance between the preservation of species and habitats, and the sustainable development of human activities, by taking into account the natural evolution of the ecosystems. Monitoring is important in this respect as it creates a standardised repetition of data collection over time, and supports the adoption of targeted tools for decision-making within the management plan.

Aim of the tool

The aim of this Guide is to support the implementation of long-term monitoring activities in MPAs as a basis to adjust management actions and initiate new, more in-depth studies adapted to MPA needs.

Main objectives

The objective of this tool is to describe and guide MPA managers in designing and implementing simple monitoring methods for the marine areas of their MPAs.


Technological infrastructure

In situ observations of the underwater environment requires specific scuba diving equipment: a wetsuit, a pair of fins, boots, a mask, a snorkel and a weight belt. For shallow coastal simple and compact equipment, such as fins, mask and snorkel, are sufficient.

It is important to have a specialised 100m waterproof watch to monitor time and duration. Moreover, it is advised to have a digital camera to take a large number of photographs at low cost, a portable waterproof GPS receiver for data geo-referencing, and geodetic buoys to mark out a transect or a permanent area.


Adequate scientific training is required for specific phases of the monitoring activities. Training exercises and prerequisites are proposed and explained in the Guide for fish visual censusing, calibrating an inventory corridor, assessing the size of individual fish and for species identification.


Investments are necessary to buy and maintain equipment costs (which may be significant for example wetsuits) and to provide training. In addition, there are likely to be time costs associated with mobilisation and the time spent on the ground.



This Guide explains the role of environmental monitoring inside MPAs and its importance. It also provides the specifics of snorkelling (describing the necessary equipment), free-diving methods and safety principles and guidelines.

Specifically, six methods are proposed:

  1. Fish visual census. Monitoring target species.
  2. Settlement of Diplodus spp. on rocky shores.
  3. Mapping and evaluation of the vitality of bio-constructors.
  4. Inventory and monitoring of the Pinna nobilis.
  5. Mapping the upper limit of the Posidonia meadow.
  6. Monitoring the populations of the edible sea urchins on rocky sea bottoms.

In each factsheet, the necessary equipment, methodologies and protocols for sampling as well as how to use the data, and training exercises and prerequisites are detailed. Training videos have also been prepared to support the implementation of some of these proposed methodologies.

Finally, five other methods are also illustrated, where snorkel surveys have been used to monitor several MPAs:

  1. Mapping the abundance of algae and invertebrates in the medio-littoral and shallow sub-tidal zones.
  2. Observations on users’ impact along an underwater trail.
  3. Collection of biological material or sediment.
  4. Census of macro-waste on the seabed.
  5. Non-native species, detection and inventory.

All these methods must, however, be adapted to each MPA’s specificities and problems. It is also advised to include problematic invasive marine species as part of the monitoring programme in the Mediterranean.

Pilot areas

This Guide is a collection of existing methodologies and protocols, which have long been established and applied to perform sampling and data collection in MPAs.

Recommended timeline of implementation

This Guide recommends the integration of long-term monitoring into existing MPA management plans. In fact, monitoring creates a standardised repetition of data collection over time, and is therefore an important tool for decision-making.


A naturalistic approach from managers and operators is an essential prerequisite to implement monitoring protocols. The sampling strategy is a complex process and must be carefully designed with the help of the scientific community. This will ensure it is representative of the whole MPA area (given technical and financial constraints), and will avoid or control bias in sampling, thereby ensuring reliable and robust results, as well as temporal relevance of the data analysis.

Although the Guide did not set a depth limit to perform snorkel surveys, it would be advised to consider that greater depths entails a higher difficulty for implementation. Further, at greater depths, it would also be more difficult to not disturb the species sampled, which could hinder the quality of the data collected.


Quantitative results

By applying the methodologies and protocols proposed in this Guide, it is expected that MPA managers will increase their knowledge of the status of key habitats and species, so as to support tailored and more effective management actions for their MPAs.

Key deliverables

Key deliverables are knowledge and know-how on the characteristics of the monitoring of marine natural heritage in MPAs.

Transfer potential

The methodologies and protocols proposed in this Guide have been already applied to perform sampling in marine areas and MPAs, and can be applied to any other MPA in the Mediterranean.


  • There are several benefits to using this type of method such as lower equipment costs, mobilisation time, time spent on the ground, the surface area covered and an easy communication between participants.
  • This document is the first step in achieving a methodological compilation for Mediterranean MPAs. However, the Guide is not complete, as species, habitats, and management issues differ from one corner of the Mediterranean to the other. The idea is to introduce a collaborative approach within the managers’ network (i.e., MedPAN and the French MPA Agency) so that this work can be enriched by each MPA’s expertise.

For further information

This guide is the product of a small project funded by MedPAN in 2013 that was led by the Conservatoire d’Espaces Naturels of the Provences-Alpes-Côte d’Azur region that was at the time in charge of the management of the Frioul archipelago Maritime Park which is now entrusted to the Calanques National Park.



Imbert M., Bonhomme P. 2014. Snorkel surveys of the marine environment, methodological guide. Parc national des Calanques, CEN PACA, GIS Posidonie. MedPAN Collection. 68 pp

Links of interest: Snorkel surveys of the Marine Environment – Methodology guide

Supporting training videos (in French, with English subtitles):

Monitoring of the marine environment with snorkel fins – Introduction

Mapping and evaluation of the vitality of bio-constructors

Mapping the upper limit of Posidonia meadows

Fish visual census. Monitoring target species


  • ACCOBAMS – Agreement on the Conservation of Cetaceans in the
  • Black Sea Mediterranean Sea and Contigous Atlantic Area
  • ACG – Association de la Continuité des Générations
  • AGIR Association
  • APAL – Coastal Protection and Development Agency
  • Blue World Institute of Marine Research and Conservation
  • Cetacean Studies Center
  • Columbares association
  • Conservatoire du littoral – International Unit
  • DMAD – Marine Mammals Research Association
  • Eco-ocean
  • Enalia Physis Environmental Research Centre
  • Environment and Resources Authority (ERA)
  • FEDERPARCHI – Italian Federation of Natural Parks and Reserves
  • French Biodiversity Office
  • Fundacion Biodiversidad
  • General Fisheries Commission for the Mediterranean (GFCM)
  • Grouper Study Group
  • IUCN – International Union for Conservation of Nature –
  • Mediterranean Center for Cooperation
  • Interdisciplinary Study Center Gaiola in charge of the Gaiola
  • Underwater Park
  • MEDCEM – Mediterranean Center for Environmental Monitoring
  • Marevivo
  • Marine Explorers Society – 20000 leagues
  • Marine Life Conservation Society
  • Mediterranean Conservation Society (akdeniz koruma dernegi)
  • Mediterranean Small Islands Initiative
  • Medwet
  • Miraceti
  • Morigenos – Slovenian Marine Mammals Society
  • NCA – Institute for Nature Conservation in Albania
  • Planète Mer
  • RODPAL – Network of NGOs in the National Park of Al Hoceima
  • Royal Albanian Foundation
  • SAD – Underwater Research Society
  • SPA/RAC – Specially Protected Areas Regional Activity Centre
  • Septentrion Environnement
  • Sharklab ADRIA – Centre for marine and freshwater biology
  • Society for the Protection of Nature in Lebanon
  • Sunce – Association for Nature, Environment and Sustainable Development
  • TUDAV – Turkish Marine Research Foundation
  • Tour du Valat
  • WWF Greece
  • WWF Mediterranean Programme Office
  • “DelTA” association
  • “Le Dauphin” association
  • “Notre Grand Bleu” association
  • “Posidonia Center for Development and Resources” NGO