Observatoire Pelagis boat surveys 2003-2021

Observatoire PELAGIS UAR 3462, University La Rochelle - CNRS

Since 2003, the Observatoire PELAGIS (La Rochelle University) participated to annual halieutic surveys, led by the IFREMER, to collect data on the distribution of marine top predators in order to estimate their relative abundance and preferred habitats in the Bay of Biscay, the Channel and the North Sea.
Each year, three observers take place on board the vessel “Thalassa” to record sightings of seabirds, marine mammals, large fish and fishing boats, from dawn to dusk. Following distance sampling methods, visual censuses are made by two observers (while the third observer is resting) from the upper platform of the boat (min. 14m above the sea level). They are placed on each side of the deck, looking ahead for marine predator with an angle of 180°. For each sighting, the species and the number of individuals are recorded, as well as the behaviour, distance and angle (upon request).

One of the main advantages of this survey lays in its ecosystemic approach, which provides information on all the components of the food web (from planktonic organisms to predators) as well as data on the environmental parameters (sea surface temperature, salinity…). Interactions between prey and predators are complex in marine ecosystems, which are submitted to strong spatio-temporal variations. Thanks to ecosystem-based surveys, observed distributions and densities of marine predators can be related to the occurrence of their prey, providing to scientists and managers a better understanding of the marine ecosystems structure.

[2022-10-20] The records on 2016-09-21 got the longitude sign swapped. they are corrected.
[2022-01-18] Data in 2020 and 2021 were appended.
[2018-04-26] Data in 2016 and 2017 were appended.

Time and group size of the sightings are not available online. They may be released upon request.

Overview

This section explains attributes included in the original dataset. OBIS-SEAMAP restricts the attributes available to the public to date/time, lat/lon and species names/counts only. Should you need other attributes described here, you are encouraged to contact the data provider.

Attributes described below represent those in the original dataset provided by the provider.
Only minimum required attributes are visible and downloadable online. Other attributes may be obtained upon provider's permission.

Attributes in dataset

Attribute (table column)	Description
oid	Unique ID number (generated by OBIS-SEAMAP)
cdnom	definition not provided
latitude	Latitude in decimal degrees
longitude	Longitude in decimal degrees
species	Species name recorded
sp_tsn	Taxonomic Serial Number added by OBIS-SEAMAP
survey	Survey name
observer	Observer name
data_producer	Data producer
data_administrator	Data administrator
obs_date	Date of the observation (time is not available)
area	Area
obs_time	Time of the observation is not available
obs_count	Group size is not available.
geom	Geometry field added by OBIS-SEAMAP