Environmental Analysis of Bluefin Tuna: Identifying its Preferred Habitat in the Mediterranean Sea

This report details the preliminary study performed for the development of the feeding and breeding habitat of bluefin tuna (BFT) in the Mediterranean Sea derived from satellite remote sensing data. The related bibliography on BFT is synthesized in order to elaborate criterion for each habitat and a first guess for the parameterization. Potential use of the habitat mapping for the BFT fisheries management and control are also described.JRC.G.4-Maritime affair

Ocean Productivity index for Fish in the Arctic Ocean: Initial assessment of satellite-derived plankton-to-fish productive habitats

The JRC explores the potentials of a satellite-derived index (the Ocean Productivity index for Fish - OPFish) at large scale to represent the production of high tropic level communities (fish) and its variability after currently observed climate change during the period 2003-2016 in the Arctic Ocean. The OPFish uses the daily detection of productive oceanic features (chlorophyll-a [CHL] fronts) from ocean colour satellite sensors at 1/24-degree resolution as a proxy for food availability to fish populations. These productive features, such as eddies or gyres, were shown to attract fish and top predators as they are active long enough (from weeks to months) to allow the development of mesozooplankton populations. Potentially eutrophic waters are excluded by removing high daily levels of surface chlorophyll-a contents (daily surface content above 10 mg CHL.m-3). The satellite monitoring of productive fronts associated with day length in the OPFish formulation provide insight on the overall capacity of the marine environment to sustain high trophic level communities. Time-series and trends of OPFish identify current climate change impacts on potential fish productivity, including seasonal deviations, which may affect fish growth and recruitment. The annual climatology levels of OPFish between 2003 and 2016 were assessed setting zero value in months of permanent night (mostly from November to February) and monthly means of index values for periods of long-day duration (mostly from May to September) filtering out low coverage of CHL due to low-light levels, ice and clouds. The climatology of OPFish in the ice-free of the Arctic Ocean, an area mostly over the continental shelf and shelf-break, displayed lower levels and more uneven distribution than in temperate shelves (e.g. North-East Atlantic) with absolute values ranging from 20 to 50% compared to 45-55% respectively. The trends of OPFish on the 2003-2016 period showed about four-fold higher regional variability and levels in the Arctic compared to the North-East Atlantic shelf area. The general OPFish trend of the Arctic Ocean is the highest observed among the regional oceans, with +2.9% per decade (in absolute value) compared to +0.5% per decade for the global ocean. In relative change, this increase translates into +16% per decade in the Arctic compared to +2.1% per decade for the global ocean. The OPFish is a plankton-to-fish index that represents the potential distribution of high trophic level (fish) productivity. Despite a necessary ongoing validation process using zooplankton and fisheries data in the Atlantic Ocean, the moderate absolute level of OPFish in the Arctic Ocean compared to temperate shelves and the substantial positive trend over 2003-2016 provide useful baseline information for future fisheries management. The high geographical disparities of level and trend of the potential fish productivity also emphasizes the necessity to take into account the spatial dimension when planing a sustainable exploitation of natural living resources.JRC.D.2-Water and Marine Resource

Towards ecosystem-based management: identifying operational food-web indicators for marine ecosystems

Modern approaches to Ecosystem-Based Management and sustainable use of marine resources must account for the myriad of pressures (interspecies, human and environmental) affecting marine ecosystems. The network of feeding interactions between co-existing species and populations (food webs) are an important aspect of all marine ecosystems and biodiversity. Here we describe and discuss a process to evaluate the selection of operational food-web indicators for use in evaluating marine ecosystem status. This process brought together experts in food-web ecology, marine ecology, and resource management, to identify available indicators that can be used to inform marine management. Standard evaluation criteria (availability and quality of data, conceptual basis, communicability, relevancy to management) were implemented to identify practical food-web indicators ready for operational use and indicators that hold promise for future use in policy and management. The major attributes of the final suite of operational food-web indicators were structure and functioning. Indicators that represent resilience of the marine ecosystem were less developed. Over 60 potential food-web indicators were evaluated and the final selection of operational food-web indicators includes: the primary production required to sustain a fishery, the productivity of seabirds (or charismatic megafauna), zooplankton indicators, primary productivity, integrated trophic indicators, and the biomass of trophic guilds. More efforts should be made to develop thresholds-based reference points for achieving Good Environmental Status. There is also a need for international collaborations to develop indicators that will facilitate management in marine ecosystems used by multiple countries.JRC.D.2-Water and Marine Resource

Scientific, Technical and Economic Committee for Fisheries (STECF) - Review of scientific advice for 2012 - Part 3 (STECF 11-15). Advice on Stocks of Interest to the European Community in areas under the jurisdiction of CCAMLR, CECAF, WECAF, ICCAT, IOTC, IAATC, GFCM, NAFO, and stocks in the North East Atlantic assessed by ICES.

The STECF review of scientific advice for 2012 Part 3 was drafted by the STECF-EWG 11-17 Working Group held in Ancona, taly from 17-21 October 2011. The Report was reviewed and adopted by the STECF at its 38th plenary session held in Brussels from 7-11November 2011.JRC.G.4-Maritime affair

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.

This report is a prospective document which aims at showing the potentials of marine productivity and fish habitat monitoring to support the EU Integrated Maritime Policies. The main proxy for marine productivity relies on the daily tracking of productive frontal systems of the surface ocean (chlorophyll-a fronts) and of the hydrological tolerance of a specific species by physical ocean models. The monitoring of pelagic habitats allows to introduce the still lacking spatial and environmental dimensions in the fisheries management to a) improve stock assessments, b) adjust fishing opportunities to the productivity of marine ecosystems, c) identify in space and time the essential fish habitats to preferably protect for sustainable catches and d) limit by-catch by differentiating target from non-target species habitats. Other applications such as the risk of ship strike with large cetaceans or the eutrophication detection illustrate the capacities of the pelagic habitat monitoring to support the integration of multiple human activities within the EU Maritime Spatial Planning. The policy exploitation of this field of research requires the integration of the fishery and environmental scientific disciplines.JRC.G.4-Maritime affair

Habitat mapping of the Atlantic bluefin tuna derived from satellite data: its potential as a tool for the sustainable management of pelagic fisheries

The feeding and spawning habitats of the overfished Atlantic bluefin tuna (BFT) are mapped in the Mediterranean Sea and used in the present proposal for selecting restricted fishing grounds. The feeding habitat is mainly traced by oceanic fronts of satellite-derived temperature and chlorophyll while the spawning habitat is mostly characterized by an important heating of surface waters. The proposal recommends opening the fishery in feeding areas in case the BFT stock is low (current situation). Only spawning areas at its latest stage could be opened once the stock has recovered to its optimum yield. Due to the possible concentration of fishing vessels if fishing areas are restricted (e.g. four-fold increase with a 1/16th restriction of the Mediterranean Sea) the inspection activities could be better targeted. Identified spawning grounds, opened or closed to fishing, could also be particularly monitored by control operations. Within the authorized areas, the habitat maps would guide fishermen to the favourable habitat reducing their costs. The habitat guided management could be able to adapt the spatial and temporal distribution of the effort to the requirements of both the fisheries¿ control and the resource. Its implementation is likely to protect the stock a) by apparently decreasing illegal fishing which accounts in the recent years for more than one-third of total catches, b) by protecting the spawners to ensure a suitable recruitment and c) by distributing the effort to respect the population structure. The first species studied is the emblematic bluefin tuna which is at high risk of collapse due to overfishing. The approach is a priori transposable to other epipelagic species of commercial importance.JRC.DG.G.4-Maritime affair

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

This scientific technical report describes the methodology and analyzes the seasonal results of a ship strike model with fin whales in the Western Mediterranean Sea. The potential risk of ship strike is computed from realistic vessel density (AIS data) and satellite-derived daily potential habitat of fin whales. The selected periods (late spring, mid-summer and autumn) highlight the variability of both maritime traffic and potential habitat of fin whales. The proposed method of combining potential habitat and AIS maritime traffic data provides an added value for policymakers. It shows the feasibility of assessing the seasonal potential risk of ship strikes with fin whales at basin scale. The Liguro-Provençal Basin shows a higher potential risk in mid-summer than late spring or autumn due to a higher traffic of passenger ferries in July-August. The Alboran Sea shows an even higher potential risk but fin whales there are hardly ever observed in this area suggesting a noise disturbance from hundreds of vessels crossing this narrow area each day. These high noise levels are likely to exceed the limit of “good conservation status” under the EU Marine Strategy Framework Directive. This work also highlights the feasibility of deriving a near real system where the daily product of potential habitat can be used on board of vessel to increase awareness or complementary to real-time plotting systems of cetaceans.JRC.G.4-Maritime affair

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

A single Ecological Niche model was developed for skipjack tuna (Katsuwonus pelamis) in the eastern central Atlantic Ocean (AO) and western Indian Ocean (IO) using an extensive set of precise spatial occurrence data from the European purse seine fleet during 1998-2014. Productive fronts of chlorophyll-a were used as proxy for food availability while mixed layer depth, sea surface temperature, oxygen concentration, salinity, current velocity and sea surface height anomaly were selected to define skipjack physical oceanographic preferences. The common environmental feeding niche identified for skipjack emphasized highly contrasted oceanographic regimes between oceans with seasonal occurrence of gyre-type productive features at mesoscale in the IO and large scale upwelling systems that seasonally shrink and swell in the AO. About 60% of free-school (FSC) sets and 46% of fishing aggregating device (FAD) sets were found within favourable feeding grounds for skipjack. About 34% of FAD sets in the AO were however found to occur at a distance further than 100 km from favourable feeding conditions, mostly in the poor environment of the Guinea Current, and 10% for the FAD sets observed in the IO, as compared to 8% for all FSC sets. The ecological role of the Guinea Current remains unclear as regards to feeding and spawning since this particularly poor environment is remote from upwelling-rich areas while skipjack is known to spawn nearby feeding grounds (income breeding strategy). The results also emphasized in the IO a higher exposure of schools to purse seiners in months where preferred feeding habitat is reduced which may result in a geographic concentration of skipjack populations at the habitat scale. Finally, the significant positive correlation observed between the annual size of favourable habitat for feeding, the annual nominal catch rates and the total catches of skipjack in the IO i) agrees with the near full exploitation of skipjack in the IO since the 2000s and in the recent years for the AO, and ii) suggests to interpret the size of favourable habitat for feeding as an indicator of carrying capacity of the environment to sustain populations of this fast-reproducing species.JRC.D.2-Water and Marine Resource

Skipjack tuna availability for purse seine fisheries is driven by suitable feeding habitat dynamics in the Atlantic and Indian Oceans

An Ecological Niche model was developed for skipjack tuna (Katsuwonus pelamis, SKJ) in the Eastern Central Atlantic Ocean (AO) and Western Indian Ocean (IO) using an extensive set of presence data collected by the European purse seine fleet (1998–2014). Chlorophyll-a fronts were used as proxy for food availability while mixed layer depth, sea surface temperature, dissolved oxygen, salinity, current intensity, and height anomaly variables were selected to describe SKJ’s abiotic environmental preferences. The resultant ecological niche included both mesoscale eddy-type productive features that displayed latitudinal range in the IO to large scale upwelling systems that shrink and swell seasonally in the AO. Overall, 83% of all free swimming school sets (FSC) and 75% of drifting fish aggregating device sets (dFAD) that contained SKJ occurred within 25 km of favorable feeding habitat. In the AO, 34% of dFAD sets were made more than 100 km away from this habitat, mostly in the surface chlorophyll-a poor environment of the Guinea Current. These distant sets represent 10% of dFAD sets in the IO and 8% of all FSC sets. Our results suggest that the Mozambique Channel in the IO, with its simultaneously favorable feeding and spawning conditions, may seasonally offer a better SKJ nursery habitat than the Guinea Current which shows a substantially poorer feeding capacity. With the exception of this latter area, our results also suggest that fishing accessibility will be higher in months where the size of the favorable feeding habitats are reduced, likely because this reduction drives a geographical contraction in SKJ populations. The observed relationship between the annual size of favorable feeding habitat and both annual catch rates and total catches in the IO is consistent with the near-full exploitation of this stock that has occurred since the 2000s. Moreover, it suggests that annual habitat size could be used as an indicator of growth capacity for this highly productive stock. Habitat monitoring, as part of a dynamic fisheries management approach, should contribute to the sustainable exploitation of SKJ by providing information on the climate-dependent aspects of stock variability and the effects of dFAD deployment in food-rich habitats.JRC.D.2-Water and Marine Resource

The Physical Environment as a Key Factor in Assessing the Eutrophication Status and Vulnerability of Shallow Sea

Abstract not availableJRC.H-Institute for environment and sustainability (Ispra