These animations detail the dynamics of preferred feeding habitat of the Atlantic bluefin tuna developed by the EC-Joint Research Centre with, as an overlay, the locations of bluefin tunas equipped with an electronic tag. These examples demonstrate the performance of the habitat modelling since the tag locations were not used to calibrate the model. It furthermore provides key information on the species behaviour and distribution to be used to improve the stock estimate and define sustainable fishing quotas.

Direct link to the playlist.

Background

The water column is the most widespread habitat of the planet and is entirely heterogeneous. The presence of gyres, eddies, fronts, temporary currents etc. defines specific conditions that are conducive to different expressions of ecosystem functioning (European Marine Board, 2013). The objective of this project is to identify the daily habitat of key marine species, mainly fish of market value, using satellite-derived data of the sea surface in support of the management and control of fisheries and the implementation of spatial  protection measures.

The target species are currently the Atlantic bluefin tuna, the European hake (recruits) and fin whale in the Mediterranean Sea as well as the yellowfin and skipjack tuna species in the tropical Atlantic and Indian Ocean. However a more generic index of productive pelagic habitats at the European scale is also in preparation to monitor the influences of climate and nutrient run-off on the productivity of marine food webs. The productivity pelagic habitat index shall also be used to provide a classification pelagic habitats at the European scale.

The feeding habitat is derived for all species while the spawning habitat is computed only for tuna species. The period covered is from March 2000 or August 2003 depending on the sensors used to yesterday (near real time).

The chosen modelling approach of species distribution relies on the niche theory, which utilizes existing knowledge of environmental and ecological processes to select a limited set of predictors and improve model interpretability. The relevant information for the habitat of specific marine species which is contained in the daily variability of surface oceans is presently fully exploited.

The potential feeding habitat was mainly derived from the occurrence of productive oceanic fronts of satellite-derived sea surface chlorophyll-a content. The potential spawning habitat was mostly inferred from the heating of surface waters (daily temperature difference in a floating window of 30 days) and surface currents. A specific range of chlorophyll content for each habitat was also shown to be discriminant. Hake nurseries were inferred using also physical limitations such as a restricted range of bottom temperature and maximum value for bottom currents since age-0 hake have limited if no mobility.

The aims of the research project may vary with the target species but generally are:

• to improve the assessment of fish stocks (standardization of Catch Per Unit Effort),
• to improve fisheries management (prediction of catch and abundance, of harvest rules based on environmental variation and regime shifts) or species protection (identification of Essential Fish Habitat or Marine Protected Areas),
• to increase knowledge on behaviour and migration patterns (for instance bluefin tuna migration in the Mediterranean Sea for spawning),
• to rise the efficiency of fisheries control (using near-real time maps).

Methodology

Two main behaviours are recognized in most fish: feeding and spawning. The JRC habitat model uses satellite data of surface chlorophyll content (CHL) from NASA sensors, i..e. SeaWiFS (1998-2010) and MODIS-Aqua (since July 2002) to compute daily habitats.

The approach used for mapping the potential habitat relates to the ecological niche modelling (environmental envelope) with specific covariates and parametrisation for each species. Water depth is used only for the fin whale (minimum depth) and hake nurseries (maximum depth). The feeding habitat was mainly traced by horizontal changes of surface chlorophyll content created by currents (CHL fronts), while the spawning habitat (bluefin tuna) was mostly inferred from the heating of surface waters. Generally, chlorophyll-a fronts were found to be preferred for the feeding and a minimum temperature was found to be preferred for the spawning habitat.

Both habitats were defined by the presence of relevant oceanographic features (CHL fronts in relation to nutrition and formation of thermal stratification in relation to reproduction) and are therefore potential and functionally-linked habitats, as opposite to effective habitats which are always difficult to produce for marine animals, especially highly migratory ones such as tunas or whales.

The daily maps of bluefin tuna potential habitats were calibrated and validated with geo-located observations from scientific surveys or fisheries operations. An independent calibration is performed for each satellite sensor providing surface chlorophyll-a content. Monthly, seasonal and annual maps of potential feeding and spawning habitat were then computed from daily maps for the last decade.

 

Maps

• Atlantic bluefin tuna by size class (above and below 25 kg in the Gulf of Mexico, North Atlantic and Mediterranean Sea)
  • Feeding
    • 15 days
    • Monthly
    • Annual
    • Multi-annual composite
    • Annual anomaly
  • Spawning
    • 15 days climatology
    • Monthly (spawning season)
    • Annual
    • Multi-annual composite
    • Annual anomaly
• Fin whale (Western Mediterranean Sea) VERSION 2! (see below the modifications from the published version1)
  • Feeding
    • 15 days
    • Monthly
    • Annual
    • Multi-annual composite
    • Annual anomaly

• Hake nurseries (Mediterranean Sea)
  • Feeding
    • 15 days climatology
    • February to June by year
    • February to June multi-annual
    • Multi-annual composite
    • Seasonal climatology
• Skipjack tuna (Central East Atlantic and West Indian Oceans, 2016)
• Small pelagics (anchovy or sardine, 2016/2017)
• Ocean Productivity Index (OPI, European Seas, 2017)

~~~~~~~~~~~~~~~~ Modifications of the fin whale potential habitat from the published paper(2012): The new optimized set of parameters are the following (CHL from MODIS-Aqua sensor):
- linear increase of daily habitat from 0.3 to 1 in the range of CHL gradient from 0.00086 to 0.0052 mgCHL/m3/km, and 1 above the latter value,
- 0.11 < CHL concentration < 0.50 mg/m3
- Water depth > 90 m The main changes are the following:
- the satellite SST front computation was removed since it created somehow either noise and/or a fragmentation of the habitat and a substantial loss of coverage. The CHL fronts are thus the main tracer of the favourable feeding habitat (with a specific CHL range). The satellite CHL is quite stable compared to the SST since it constitutes an optical observation of several metres of the surface waters instead of few microns for the thermal observation.
- because MODIS-Aqua is showing more and more stripes on the CHL data, an increased smoothing was also performed to remove them in the new scheme as they resulted in small linear and totally artificial fronts of low intensity.
- the filter size for computing the fronts (horizontal gradient) is smaller than before (3 instead of 5 pixels) so that the habitat is now available substantially closer to the coast. - Non-habitat is furthermore defined outside the favourable range so that, notably, winter coverage has increased and the overall habitat size decreased in relative value of the basin surface (%). The consequence of these changes is that the favourable feeding habitat is much more continuous and less fragmented than before. The oceanic features (productive fronts) are substantially more continuous and visible than before and the fronts are somehow wider due to the smoothing. The back side of reducing the fragmentation is that the mean closest distance to habitat is about double than for version 1 but it is believed that at least part of this apparent decrease of performance is due to the increased fragmentation and noise which was in the version 1 when using the satellite SST. Therefore, the predictability is likely to be similar, with a higher focus on hot spots of preferred habitat.

~~~~~~~~~~~~~~~~

Collaborations

This research initiatives are performed with the full collaboration of numerous research institutes across Europe.

• Atlantic bluefin tuna: After an initial collaboration with IFREMER (France), the current extension of the habitat over the North Atlantic and the Gulf of Mexico is performed within an international collaboration of scientific experts from Mexico, the USA, Canada, Portugal, Spain, France, Italy, Croatia, Greece, Turkey, Denmark and Japan.
• Tropical tunas species: IRD - France, AZTI and IEO - Spain
• European Hake: MEDITS scientific community - Italy: COISPA, SIBM-Genova University, CIBM, UNICA, Rome University, CNR-IAMC, Bari University. France: IFREMER. Spain: IEO. Malta: MRRA. Greece: IMBC, HCMR.
• Fin whale: Italy: TETHYS, ISPRA, CETUS, CIMA Foundation. France: ÉcoOcéan, GIS3M, GREC, Souffleurs d'Écume, WWF-France, La Rochelle University, IFREMER. Spain: ALNITAK, CIRCÉ. Switzerland: Swiss Cetacean Society. International: NATO-NURC.

Publications & Press release

Peer-reviewed publications

Liquete C, Piroddi C, Macías D, Druon JN and Zulian G (2016)
Ecosystem services sustainability in the Mediterranean Sea: assessment of status and trends using multiple modelling approaches, Nature, Scientific Reports | 6:34162 | DOI: 10.1038/srep34162 | Full text download in open access | See Press release

Fossi MC, Romeo T, Baini M, Panti C, Marsili L, Campani T, Canese S, Galgani F, Druon JN, Airoldi S, Taddei S, Fattorini M, Brandini C, Lapucci C (2016)
Microplastics, convergence areas and fin whales in the Marine Protected Area Pelagos Sanctuary (northwestern Mediterranean Sea), Frontiers in Marine Science | submitted |

Druon JN, Fromentin JM, Hanke A, Arrizabalaga H, Damalas D, Tičina V, Quílez-Badia G, Ramirez K, Arregui I, Tserpes G, Reglero P, Deflorio M, Oray I, Karakulak SF, Megalofonou P, Ceyhan T, Grubišić L, MacKenzie BR, Lamkin J, Afonso P and P Addis (2016)
Habitat suitability of the Atlantic bluefin tuna by size class: an ecological niche approach, Progress in Oceanography 142:30-46. DOI: 10.1016/j.pocean.2016.01.002 | Full text download in open access |Supplementary Material | See Press release

Briscoe D, Hobday A, Carlisle A, Scales K, Eveson P, Arrizabalaga H, Druon JN, Fromentin JM (2016)
Ecological bridges and barriers in pelagic ecosystems, Deep Sea Research Part II: Topical Studies in Oceanography IN PRESS. DOI: 10.1016/j.dsr2.2016.11.004 | Full text download in open access

Druon JN, Fiorentino F, Murenu M, Knittweis L, Colloca F, Osio C, Mérigot B, Garofalo G, Mannini A, Jadaud A, Sbrana M, Scarcella G, Tserpes G, Peristeraki P, Carlucci R and J Heikkonen (2015)
Modelling of European hake nurseries in the Mediterranean Sea: an ecological niche approach, Progress in Oceanography 130:188-204 |Full text download in open access

Druon JN, Panigada S, David L, Gannier A, Mayol P, Arcangeli A, Cañadas A, Laran S, Di Méglio N and P Gauffier (2012)
Potential feeding habitat of fin whales in the western Mediterranean Sea: an environmental niche model, Marine Ecology Progress Series 464:289-306 |Full text and complement download in open access

Druon JN, Fromentin JM, Aulanier F, Heikkonen J  (2011)
Potential feeding and spawning habitats of Atlantic bluefin tuna in the Mediterranean Sea, Marine Ecology Progress Series 439:223-240 | Full text in open access| See Press release

Druon JN (2010)
Habitat Mapping of the Atlantic Bluefin Tuna Derived from Satellite Data: Its Potential as a Tool for the Sustainable Management of Fisheries, Marine Policy;34(2):293-297 | Full text (not open access)

Other publications and reports

Druon J-N, Chassot E., Murua H, Soto M (2016)
Preferred feeding habitat of skipjack tuna in the eastern central Atlantic and western Indian Oceans: relations with carrying capacity and vulnerability to purse seine fishing, IOTC-WPTT-18, 31 | Full resolution PDF;IOTC PDF

Druon J-N, Chassot E., Floch L, Maufroy A (2015)
Preferred habitat of tropical tuna species in the Eastern Atlantic and Western Indian Oceans: a comparative analysis between FAD-associated and free-swimming schools, IOTC-WPTT-17, 31 | Full text download

Druon J-N (2014)
Monitoring pelagic habitats to support future EU policies. Strategic view on how the daily monitoring of marine water-column habitats will support the future EU Integrated Maritime Policy (MSP, CFP, MSFD) to stimulate ecosystem health and blue growth, European Commission Report (EUR 26628 EN), doi: 10.2788/69671 | Full text download

Vaes T, Druon J-N (2013)
Mapping of potential risk of ship strike with fin whales in the Western Mediterranean Sea. A scientific and technical review using the potential habitat of fin whales and the effective vessel density, European Commission Report (EUR 25847 EN), doi: 10.2788/8520 | Full text download | See JRC Headline

Aulanier F, Druon J-N (2010)
The habitat model of marine species using satellite remote sensing: technical aspects, European Commission Report (EUR 23790 EN), doi:10.2788/20881 | Full text download

Druon J-N (2009)
Environmental analysis of Bluefin Tuna: Identifying its preferred habitat in the Mediterranean Sea, European Commission Report (EUR 23790 EN), doi: 10.2788/20881 | Full text download

Press release

• JRC Headline 2016: Quantifying the use and availability of marine ecosystem services for humans
• JRC Headline 2016: New habitat model allows dynamic and smart management of Atlantic bluefin tuna
• Press release: Satellite data can help protect bluefin tuna
• JRC Headline: Mapping the potential risk of ship strike with fin whales in the Western Mediterranean Sea

ACCESS TO HABITAT MAPS (Windows and Linux)
(Atlantic bluefin tuna, fin whale, hake nurseries)

Habitat data are available for research on request, please contact:

jean-noel.druon@ec.europa.eu

Other habitat maps and data at NOAA Atlas of the Gulf of Mexico (bluefin tuna) and at EMIS (Environmental Monitoring Information System) in European Seas (bluefin tuna)

Generic index of potential fish productivity (description)

(daily update at 16.00 Central European Time)

Real-time mapping of bottom trawling preferable avoidance

based on habitat estimation of hake nurseries (Druon et al. 2015)

Download real-time maps: full resolution image (.png), or Google Earth (.kmz) for zooming in your area.

 

EN: Download presentation to MEDAC (07/06/2016).

IT: Scaricare la presentazione di Mazara del Vallo (14/10/2016).

FR: Téléchargez la présentation de Sète (13/12/2016).

Send to jean-noel.druon@ec.europa.eu a recipient email address to daily receive the map in both formats.
Visualize animation for:

•  daily variability (.gif),
• monthly variability (.gif),

Potential habitat of fin whale is daily produced in near-real time and sent to a restricted list of users (below with two weeks delay, 3-day composite, click on the image for a larger view):