Trends in Productivity and Biomass Yields in the Mediterranean Sea Large Marine Ecosystem During Climate Change

Transcription

1 Trends in Productivity and Biomass Yields in the Mediterranean Sea Large Marine Ecosystem During Climate Change Stergiou K.I. 1,2, Somarakis S. 1, Triantafyllou G. 3, Tsiaras K.P. 3, Giannoulaki M. 1, Petihakis G. 3, Machias A. 1, Tsikliras A.C. 2 1 Institute of Marine Biological Resources and Inland Waters, Hellenic Centre for Marine Research 2 Department of Zoology, School of Biology, Aristotle University of Thessaloniki 3 Institute of Oceanography, Hellenic Centre for Marine Research

2 General facts 3 continents 22 countries 2.5 million km² area 1% of world s oceans 132 million population 28% of marine oil traffic 6% of marine species 650 fish species of which > 200 commercial 5% of fish species are invasive Seamounts 0.41% of world Extended coastline Publishing in many languages Most of scientific info in grey literature Stergiou & Tsikliras (2006) ESEP, Coll et al. (2010), Plos-One

3 Water circulation High salinity Concentration basin (negative water balance) Surface Atlantic water enters the Mediterranean Deep Mediterranean water flows out into the Atlantic Nile damming affected the hydrology of the Eastern basin

4 Temperature and salinity N-NW S-SE

5 Trophic status Generally oligotrophic, especially the S-SE part, compared to the Atlantic and the Black Sea. Locally eutrophic, especially in the W, N parts.

6 Fish species richness All fish species (n = 625) N-NW Alien fish richness increases All fish richness declines S-SE Alien fish species (n = 127) Fish species richness in the Mediterranean Sea based on superimposed expert-drawn maps. Colors express species occurrence from blue (little or no occurrence) to red (highest occurrence). Coll et al. (2010), Plos-One

7 Fishing and fisheries Fishing is practiced since ancient times Highly diverse fisheries, varying geographically because of different environmental and socio-economic situations International management structures have not been enforced sufficiently: Regular assessments in the GFCM & STECF-SGMED started only about 10 years ago Large number of boats, mostly of low tonnage Multispecies fisheries Lack of big industrial fleets Multitude of ports and shelters

8 Fisheries management Management is based mainly on technical measures: Minimum landing size for certain species Minimum mesh size Nets length Seasonal closures Banned gears e.g. pelagic trawl totally banned in Spain, Greece, Turkey Very recently TACs have been established for anchovy and sardine in Spain (Alboran Sea) and Italy (Sicily) Bottom trawling is banned: 1.5 nm from shore/50 m bottom depth over seagrass beds < 1000 m depth

9 Fisheries management Several MPAs have been established, mostly of small spatial scale 9 /regional_work/marine_protected_areas_regional_review/

10 Fishing effort The number of all types of Med EU fishing vessels declined since the early 1990s. Number of EU fishing vessels engaged to trawl, purse seine and small-scale fishing. Tzanatos et al. (2014), Climate Change

11 Total landings Total landings are declining across all 3 MED subareas. max t 2006 max t 1984 max t W Mediterranean t C Mediterranean t E Mediterranean t (Tsikliras et al. submitted)

12 Total landings - species Landings - mostly small pelagics: sardine, anchovy and round sardinella S. pilchardus 14% Engraulis encrasicolus 9% Sardina pilchardus 23% Engraulis encrasicolus 18% Other 44% Engraulis encrasicol us 10% Other 42% Sardina pilchardus 15% Boops boops 5% Trachurus spp 9% Sardinella spp 7% Sardinella spp 7% Other 62% Sardinella spp 4% W Med: sardine (23%), anchovy (10%), Trachurus spp. (9%), sardinella (7%) C Med: anchovy (18%), sardine (15%), sardinella (7%) Depleted E Med: sardine (14%), anchovy (9%), bogue (5%), sardinella (4%) (Tsikliras et al. submitted)

13 Total landings - species The most important in terms of landings demersal species are: Hake Merluccius merlucius Common pandora Pagellus erythrinus Bogue Boops boops W Med: hake, bogue C Med: hake, common pandora, deep-water rose shrimp, Mullus spp. E Med: natantia decapods, bogue Red mullets Mullus spp. Deep-water rose shrimp Parapeneus longirostris

14 Exploitation status Most stocks are overfished, only a few fisheries are developing, some recover. Overexploited+depleted stocks >50% (Tsikliras et al. 2014, Acta Adriatica) 100% 80% W C E Recovering Developing 81% of stocks assessed are overfished (Colloca et al. 2013, Fish Fisheries) 60% 40% 20% Depleted 0% Year Fishing pressure intensified continuously from 1990 to 2010, with more and more fish caught as juveniles (Vassilakopoulos et al. 2014, Current Biology)

15 Climate change Mediterranean sea surface temperature (SST) anomalies generally parallel the Northern Hemisphere Temperatures anomalies Tzanatos et al. (2014), Clim Change

16 Climate change SST changes are largely similar in W, C and E Med, and indicate an increase of about 1.5 o C during the last 40 years. From NOAA from Alheit et al. (2014) J Mar Systems

17 Landings and climate change EU Mediterranean countries There is a signal of climate on Landings per Unit of Effort (LPUE). LPUE of different gears for several species are either positively or negatively related to SST. Tzanatos et al. (2014) Climate Change

18 Landings and climate change Negative regime shifts of landings anomalies Positive shifts of landings anomalies Significant (p>0.05) shifts in Med landings indicated by Rodionov s Regime Shift Index (RSI). The grey lines indicate the RSI values of the species experiencing regime shifts. The blue bars show the timing and number of species experiencing shifts. The red dotted lines denote the time frame when >75% of the total shifts in species landings occurred. (Tzanatos et al Climate Change)

19 Landings and climate change There is a signal of climate on landings. The landings anomalies were either positive or negatively related to SST. Tzanatos et al. (2014), Climate Change

20 Mean Temperature of the Catch (MTC) MTC: evaluates the effect of sea warming on exploited marine communities (Cheung et al. 2013) o C per decade 1.05 o C per decade 0.29 o C per decade Western Mediterranean Central Mediterranean Eastern Mediterranean MTC increased across all 3 Med subareas and the increase was highly correlated with SST anomaly (bars). The landings do not include those of the Lessepsian species because they are not officially recorded. (Tsikliras & Stergiou 2014, Mar Ecol Progr Ser)

21 Climate change and alien fish species Alien fish species and especially Lessepsian ones have greatly expanded in the Mediterranean in terms of number of species and abundance. Example: Siganids now represent about 80% of the abundance of herbivorous fish in E Mediterranean coastal waters (Bariche et al. 2004). Upeneus moluccensis Goldband goatfish Marbled spinefoot Siganus rivulatus Por's goatfish Upeneus pori Some commercially important Lessepsian fishes Etrumeus sadina

22 Alien species anomaly Climate change and alien species New alien species anomalies (black line) is significantly correlated with the Northern Hemisphere Temperature (NHT) anomalies during The vertical line shows the 1998 temperature shift. r=0.89, p=0.015 NHT anomalies, Raitsos et al. (2010) Limnology and Oceanography

23 Mean temperature of the catch Mean temperature of the catch MTC and potential Lessepsian landings Mean temperature of the catch Steeper MTC rates when hypothetical landings for Lessepsian species were included o C per decade 1.08 o C per decade 0.32 o C per decade Western Mediterranean Central Mediterranean Eastern Mediterranean 20 y = 0.058x R² = y = 0.108x R² = y = x R² = Year Year Year Assuming the same simulation scenario for each subarea: Lessepsian species have 25 o C temperature preference starting in 2003 with 1500 t and increasing 500 t per year reaching 5000 t in 2010

24 Annual probability maps and habitat allocation of main MED species Acoustic surveys ichthyoplankton surveys pelagic trawl data at different seasons, years and Mediterranean areas together with environmental variables have been used to develop habitat maps. Environmental conditions: Satellite data Habitat maps at a larger spatial scale Statistical model: GAMs o 40o SST in oc to to to o o 22o 23o 24o 25o 26o 27o Siapatis et al. (2008), Tugores et al. (2011), MEPS, Giannoulaki et al. (2013), Fisheries Oceanography

25 Annual probability maps and habitat allocation of main MED species We firstly obtained annual probability maps (and subsequently mean probability and SD maps for the whole Mediterranean) to to to Giannoulaki et al. (2013), Fisheries Oceanography

26 Annual probability maps and habitat allocation of main MED species Spawning grounds (summer) From the probability maps we derived habitat allocation maps for various pelagic species, here e.g. anchovy. Nurseries (Late autumn) Preferential: High mean, low StDev Occasional: High mean, high StDev Rare: Low mean Giannoulaki et al. (2013), Fisheries Oceanography

27 A full life-cycle anchovy model (from eggs to adults, stage- and age specific) N Aegean supports one of the main anchovy stocks in the Mediterranean Because of its increased productivity river inputs Black Sea Water inflow

28 A full life-cycle anchovy model (from eggs to adults, stage- and age specific) An anchovy model coupled to a biophysical model has been developed for N Aegean and is currently extended also to the whole Mediterranean. The hydrodynamic/biogeochemical model is currently operational within the HCMR POSEIDON forecast system. POSEIDON operational atmospheric model Suite of Models Hydrodynamic model POM (Blumberg and Mellor, 1983) Biogeochemical model ERSEM (Baretta et al., 1995) LTL model Organic matter, nutrients is two-way coupled to Currents, Temperature, Zooplankton Anchovy IBM model Bioenergetic model Population model Movement model

29 A full life-cycle anchovy model (from eggs to adults, stage- and age specific)

30 The biogeochemical model -ERSEM-II It describes the pelagic food web with: 4 phytoplankton groups bacteria 3 zooplankton groups and takes into full account the microbial loop. (Baretta et al. 1995; Petihakis et al. 2002) Anchovy feeds on microzooplankton and mesozooplankton depending on life stage.

31 Mediterranean future climate simulations - preliminary results Simulations for and periods Comparison between 1980 and 2080

32 Mediterranean future climate simulations - preliminary results Biomass declines by 15% because of zooplankton decline but mainly because increased temperature leads to increased respiration and thus lower weight

33 Thank you