Stochastic bioeconomic modelling of alternative management measures for anchovy in the Mediterranean Sea

Abstract Maravelias, C. D., Hillary, R., Haralabous, J., and Tsitsika, E. V. 2010. Stochastic bioeconomic modelling of alternative management measures for anchovy in the Mediterranean Sea. – ICES Journal of Marine Science, 67: 1291–1300. The purse-seine fishery for anchovy in the Aegean Sea consists of two main fleet segments (12–24 and 24–40 m vessels); this paper investigates economically and biologically preferable effort and capacity scenarios for the fishery. Attention is paid to a bioeconomic analysis of fleets composed of segments with varying levels of efficiency (in terms of catch rate) and costs (fixed and variable) and the role this might play in optimal effort allocation at a fleet level. An age-structured stochastic bioeconomic operating model for Aegean anchovy (Engraulis encrasicolus) is constructed. It attempts to account robustly for the multiple uncertainties in the system, including (i) the effort–fishing mortality relationship, (ii) the selectivity, and (iii) the stock–recruit dynamics of the population. A method is proposed for determining the economically optimal level of long-term effort in a fishery such as this, with similar characteristics in terms of stock dynamics, fishery, and markets. Lower values of effort and capacity are predicted to yield greater future profit when viewing the fleet in its entirety, but even lower values may be advisable to maintain the long-term biological integrity of the stock. The results may prove useful in balancing the productivity of the stock with the harvesting capacity of the fleet, while managing to ensure the long-term profitability of the fleet along with the sustainability of the resource.

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“Crash landing” obligation for Mediterranean mixed fisheries: Evaluation of management strategies using bioeconomic modelling in the Aegean Sea

Scientia Marina ◽

10.3989/scimar.04881.08a ◽

2019 ◽

Vol 83 (2) ◽

pp. 143 ◽

Cited By ~ 3

Author(s):

Maria Christou ◽

Francesc Maynou ◽

George Tserpes ◽

Konstantinos I. Stergiou ◽

Christos D. Maravelias

Keyword(s):

Juvenile Fish ◽

Management Strategies ◽

Aegean Sea ◽

Sustainable Fisheries ◽

Management Measures ◽

Bioeconomic Modelling ◽

Fisheries Policy ◽

Ne Mediterranean ◽

The Common

Minimizing unwanted catches is a major milestone for achieving sustainable fisheries. In the framework of the Common Fisheries Policy, a landing obligation is being established progressively in European waters (Article 15, EU Regulation 1380/2013). Supplementary management measures have been proposed to support and enhance the effectiveness of this new regime. In this context, the effect of the landing obligation on a demersal mixed fishery (coastal and trawl fleet) in the Aegean Sea (NE Mediterranean Sea) was assessed in terms of both biological and economic sustainability. Our results show that the landing obligation alone does not ensure sustainable fisheries. Management action should be directed to the introduction of additional measures. Evidence suggests that improving selectivity and protecting the nursery grounds are possible solutions to decrease discards and ensure sustainable fisheries in the long term. The landing obligation can have a role in incentivizing the adoption of these management measures that ensure lower fishing mortality on juvenile fish.

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Long-term monitoring programme of the hydrological variability in the Mediterranean Sea: a first overview of the HYDROCHANGES network

Ocean Science ◽

10.5194/os-9-301-2013 ◽

2013 ◽

Vol 9 (2) ◽

pp. 301-324 ◽

Cited By ~ 37

Author(s):

K. Schroeder ◽

C. Millot ◽

L. Bengara ◽

S. Ben Ismail ◽

M. Bensi ◽

...

Keyword(s):

Time Series ◽

Mediterranean Sea ◽

Sampling Interval ◽

Global Changes ◽

Hydrological Variability ◽

Long Term Monitoring ◽

The Mediterranean ◽

Set Up ◽

Term Monitoring

Abstract. The long-term monitoring of basic hydrological parameters (temperature and salinity), collected as time series with adequate temporal resolution (i.e. with a sampling interval allowing the resolution of all important timescales) in key places of the Mediterranean Sea (straits and channels, zones of dense water formation, deep parts of the basins), constitute a priority in the context of global changes. This led CIESM (The Mediterranean Science Commission) to support, since 2002, the HYDROCHANGES programme (http//www.ciesm.org/marine/programs/hydrochanges.htm), a network of autonomous conductivity, temperature, and depth (CTD) sensors, deployed on mainly short and easily manageable subsurface moorings, within the core of a certain water mass. The HYDROCHANGES strategy is twofold and develops on different scales. To get information about long-term changes of hydrological characteristics, long time series are needed. But before these series are long enough they allow the detection of links between them at shorter timescales that may provide extremely valuable information about the functioning of the Mediterranean Sea. The aim of this paper is to present the history of the programme and the current set-up of the network (monitored sites, involved groups) as well as to provide for the first time an overview of all the time series collected under the HYDROCHANGES umbrella, discussing the results obtained thanks to the programme.

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Mediterranean Sea climatic indices: monitoring long term variability and climate changes

10.5194/essd-2018-51 ◽

2018 ◽

Author(s):

Athanasia Iona ◽

Athanasios Theodorou ◽

Sarantis Sofianos ◽

Sylvain Watelet ◽

Charles Troupin ◽

...

Keyword(s):

Climate Change ◽

Time Series ◽

Mediterranean Sea ◽

Climate Changes ◽

Salt Content ◽

Climatic Indices ◽

In Situ Observations ◽

The Mediterranean

Abstract. We present a new product composed of a set of thermohaline climatic indices from 1950 to 2015 for the Mediterranean Sea such as decadal temperature and salinity anomalies, their mean values over selected depths, decadal ocean heat and salt content anomalies at selected depth layers as well as their long times series. It is produced from a new high-resolution climatology of temperature and salinity on a 1/8° regular grid based on historical high quality in situ observations. Ocean heat and salt content differences between 1980–2015 and 1950–1979 are compared for evaluation of the climate shift in the Mediterranean Sea. The spatial patterns of heat and salt content shifts demonstrate in greater detail than ever before that the climate changes differently in the several regions of the basin. Long time series of heat and salt content for the period 1950 to 2015 are also provided which indicate that in the Mediterranean Sea there is a net mean volume warming and salting since 1950 with acceleration during the last two decades. The time series also show that the ocean heat content seems to fluctuate on a cycle of about 40 years and seems to follow the Atlantic Multidecadal Oscillation climate cycle indicating that the natural large scale atmospheric variability could be superimposed on to the warming trend. This product is an observations-based estimation of the Mediterranean climatic indices. It relies solely on spatially interpolated data produced from in-situ observations averaged over decades in order to smooth the decadal variability and reveal the long term trends with more accuracy. It can provide a valuable contribution to the modellers' community, next to the satellite-based products and serve as a baseline for the evaluation of climate-change model simulations contributing thus to a better understanding of the complex response of the Mediterranean Sea to the ongoing global climate change. The product is available here: https://doi.org/10.5281/zenodo.1210100.

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New Mediterranean Marine biodiversity records (June 2013)

Mediterranean Marine Science ◽

10.12681/mms.450 ◽

2013 ◽

Vol 14 (1) ◽

pp. 238 ◽

Cited By ~ 7

Author(s):

I. SIOKOU ◽

A.S. ATES ◽

D. AYAS ◽

J. BEN SOUISSI ◽

T. CHATTERJEE ◽

...

Keyword(s):

Mediterranean Sea ◽

Aegean Sea ◽

Marine Biodiversity ◽

Red Data Book ◽

Gulf Of Tunis ◽

The North ◽

Levantine Sea ◽

Data Book ◽

The Mediterranean ◽

Flora Of Cyprus

This paper concerns records of species that have extended their distribution in the Mediterranean Sea. The finding of the rare brackish angiosperm Althenia filiformis in the island of Cyprus is interesting since its insertion in the Red Data Book of the Flora of Cyprus is suggested. The following species enriched the flora or fauna lists of the relevant countries: the red alga Sebdenia dichotoma (Greece), the hydrachnid mite Pontarachna adriatica (Slovenia), and the thalassinid Gebiacantha talismani (Turkey). Several alien species were recorded in new Mediterranean localities. The record of the burrowing goby Trypauchen vagina in the North Levantine Sea (Turkish coast), suggests the start of spreading of this Lessepsian immigrant in the Mediterranean Sea. The findings of the following species indicate the extension of their occurrence in the Mediterranean Sea: the foraminifer Amphistegina lobifera (island of Zakynthos, Greece), the medusa Cassiopea andromeda (Syria), the copepod Centropages furcatus (Aegean Sea), the decapod shrimp Melicertus hathor (island of Kastellorizo, Greece), the crab Menoethius monoceros (Gulf of Tunis), the barnacles Balanus trigonus, Megabalanus tintinnabulum, Megabalanus coccopoma and the bivalves Chama asperella, Cucurbitula cymbium (Saronikos Gulf, Greece).

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Sponge community variation along the Apulian coasts (Otranto Strait) over a pluri-decennial time span. Does water warming drive a sponge diversity increasing in the Mediterranean Sea?

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315419000651 ◽

2019 ◽

Vol 99 (7) ◽

pp. 1519-1534 ◽

Cited By ~ 1

Author(s):

Gabriele Costa ◽

Giorgio Bavestrello ◽

Valerio Micaroni ◽

Maurizio Pansini ◽

Francesca Strano ◽

...

Keyword(s):

Mediterranean Sea ◽

Benthic Communities ◽

Time Span ◽

Biodiversity Monitoring ◽

Sponge Diversity ◽

Community Variation ◽

The Mediterranean ◽

Changes Over Time ◽

Mass Mortalities

AbstractClimate change and heavy anthropic pressures are giving rise to important modifications in the rocky benthic communities of the Mediterranean Sea. In particular, sponge assemblages have been deeply affected due to the susceptibility of some species to dramatic phenomena such as mass mortalities or widespread variations in the abundance of other species. For this reason, long-term biodiversity monitoring of the sponge assemblages is important for understanding the direction of changes over time. We studied the sponge fauna living off Tricase Porto (Otranto Strait) and compared its composition with the results of a study conducted in the same area 50 years ago. The comparison indicated that the sponge diversity of this area has strongly increased in the last 50 years and a large number of the sponges recorded in the old survey are still present in the recent community. This evidence matches with other results obtained from different localities of the Mediterranean Sea indicating an increase of sponge diversity, possibly due to the present water warming. The description of two new Demosponge species, Diplastrella boeroi sp. nov. and Spirastrella angulata sp. nov., is also provided.

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Hemiasterella aristoteliana n. sp. (Porifera, Hadromerida) from the Aegean Sea with a discussion on the family Hemiasterellidae

Bijdragen tot de Dierkunde ◽

10.1163/26660644-06101004 ◽

1991 ◽

Vol 61 (1) ◽

pp. 43-49 ◽

Cited By ~ 7

Author(s):

Eleni Voultsiadou-Koukoura ◽

R.W.M. van Soest

Keyword(s):

New Species ◽

Mediterranean Sea ◽

Aegean Sea ◽

Shallow Waters ◽

The Family ◽

The Status ◽

Northern Aegean Sea ◽

The Mediterranean ◽

First Time

A representative of the genus Hemiasterella Carter, 1879 was found for the first time in the Mediterranean Sea during sampling in the shallow waters of the northern Aegean Sea. The new species, H. aristoteliana, is compared with Atlantic Hemiasterella elongata Topsent, 1928. The status of the family Hemiasterellidae is discussed.

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Simulating the Effects of Alternative Management Measures of Trawl Fisheries in the Central Mediterranean Sea: Application of a Multi-Species Bio-economic Modeling Approach

Frontiers in Marine Science ◽

10.3389/fmars.2019.00542 ◽

2019 ◽

Vol 6 ◽

Cited By ~ 7

Author(s):

Tommaso Russo ◽

Lorenzo D'Andrea ◽

Simone Franceschini ◽

Paolo Accadia ◽

Andrea Cucco ◽

...

Keyword(s):

Mediterranean Sea ◽

Economic Modeling ◽

Central Mediterranean ◽

Alternative Management ◽

Modeling Approach ◽

Management Measures ◽

Central Mediterranean Sea ◽

Trawl Fisheries

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Simulating Bleaching: Long-Term Adaptation to the Dark Reveals Phenotypic Plasticity of the Mediterranean Sea Coral Oculina patagonica

Frontiers in Marine Science ◽

10.3389/fmars.2019.00662 ◽

2019 ◽

Vol 6 ◽

Cited By ~ 2

Author(s):

Tal Zaquin ◽

Paul Zaslansky ◽

Iddo Pinkas ◽

Tali Mass

Keyword(s):

Phenotypic Plasticity ◽

Mediterranean Sea ◽

The Mediterranean

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Carbonate System and Acidification of the Adriatic Sea

10.5194/egusphere-egu2020-10977 ◽

2020 ◽

Author(s):

Valentina Turk ◽

Nina Bednarsek ◽

Jadran Faganeli ◽

Blaženka Gasparovic ◽

Michele Giani ◽

...

Keyword(s):

Mediterranean Sea ◽

Adriatic Sea ◽

Microbial Community Composition ◽

Aegean Sea ◽

Total Alkalinity ◽

The Black Sea ◽

Po River ◽

Saturation State ◽

Northern Adriatic ◽

The Mediterranean

Although the marginal seas represent only 7% of the total ocean area, the CO2 fluxes are intensive and important for the carbon budget, exposing to an intense process of anthropogenic ocean acidification (OA). A decline in pH, especially in the estuarine waters, results also from the eutrophication-induced acidification. The Adriatic Sea is currently a CO2 sink with an annual flux of approximately -1.2 to -3 mol C m-2 yr-1 which is twice as low compared to the net sink rates in the NW Mediterranean (-4 to -5 mol C m-2 yr-1). Based on the comparison of two winter cruises carried out in in the 25-year interval between 1983 and 2008, acidification rate of 0.003 pHT units yr&#8722;1 was estimated in the northern Adriatic which is similar to the Mediterranean open waters (with recent estimations of &#8722;0.0028 &#177; 0.0003 units pHT yr&#8722;1) and the surface coastal waters (-0.003 &#177; 0.001 and -0.0044 &#177; 0.00006 pHT units yr&#8722;1). The computed Revelle factor for the Adriatic Sea, with the value of about 10, indicates that the buffer capacity is rather high and that the waters should not be particularly exposed to acidification. Total alkalinity (TA) in the Adriatic (2.6-2.7 mM) is in the upper range of TA measured in the Mediterranean Sea because riverine inputs transport carbonates dissolved from the Alpine dolomites and karstic watersheds. The Adriatic Sea is the second sub-basin (319 Gmol yr-1), following the Aegean Sea (which receives the TA contribution from the Black Sea), that contribute to the riverine TA discharges into the Mediterranean Sea. About 60% of the TA inflow into the Adriatic Sea is attributed to the Po river discharge with TA of ~3 mM and TA decreases with increasing salinity. Saturation state indicates that the waters of the Adriatic are supersaturated with respect to calcite (&#937;Ca) and aragonite (&#937;Ar) throughout the year. However, saturation states are considerably lower in the bottom water layers, due to the prevalence of benthic remineralization processes in the stratification period. The seasonal changes of the chemical and environmental conditions and relatively small size of the Adriatic Sea area the microbial community composition, function (growth, enzymatic activity) and carbon and nitrogen biogeochemical cycles. Significant effects on calcifying organisms and phytoplankton are expected while the effects of possible OA on microbially-driven processes are not known yet.

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A scale-independent model for land-locked seas with application to the Messinian salinity crisis

10.5194/egusphere-egu2020-10494 ◽

2020 ◽

Author(s):

Paul Meijer

Keyword(s):

Mediterranean Sea ◽

Independent Solution ◽

Aegean Sea ◽

Basic Element ◽

Messinian Salinity Crisis ◽

Elevated Salinity ◽

Levantine Basin ◽

The Mediterranean ◽

Atmospheric Heat

While the Mediterranean Sea is, since the Middle Miocene, a nearly completely land-locked basin indeed, it is itself comprised of several smaller semi-enclosed seas. What the Mediterranean Sea as a whole is to the Atlantic Ocean, are the Adriatic Sea or Aegean Sea to the Ionian-Levantine basin, for example. In the discussions regarding the Messinian salinity crisis the marginal basins of the Mediterranean play a prominent role because it is from these parts that the sedimentary record has been uplifted and become exposed.In view of this and with an aim to contribute insight from the field of modelling, we focus on the basic element: a single marginal basin, subject to atmospheric forcing and exchanging water through a seaway with an adjacent larger basin. The equations are derived in dimensionless form and a universal, scale-independent, solution for basin salinity obtained. The analysis yields two dimensionless ratios which control basin behaviour in terms of salinity and response time.&#160;Application of the theoretical model to the Messinian salinity crisis sheds new light on the formation of gypsum in marginal basins that were separated from the main Mediterranean by a sill, gives insight about the role of atmospheric heat exchange, and underlines the previous finding that, at elevated salinity, marginal basins respond to periodic climate variation (e.g. due to precession) with a significant lag.

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