2/17/2012
Stock Biomass, Species Composition, Depth and Seasonal Distribution of Eelasmobranches in the Iskenderun Bay, Northeastern Mediterranean Coast of Turkey
Cemal Turan
Fisheries Faculty, Mustafa Kemal University, Hatay, Turkey.
Monitoring of Elasmobranche Species
Project Title: The Effects of Global Climate Change on Fish Populations in the Eastern Mediterranean Sea Supportin Organization: The Ministry of Agriculture and Rural Affairs
Coordinator: Cemal Turan
Starting and Ending: 2009-2012
1 2/17/2012
SURVEY AREA
Iskenderun Bay located along the northeastern Levantine basin.
The bay has a euphotic water column, and nutrition amounts are 2-4 times higher than offshore
The bay has a rocky bottom in the southeast and northeast
The bay is reseaving high number of indo- Pacific migrant species (invasive).
2 2/17/2012
The bay has the largest fishery fleets of the Mediterranean coast of Turkey.
The composition and amount of fishery is changing in years due to the invasive species or/and climate change
Total biomass, species composition, depth distribution, seasonal distribution and abundance of elasmobranches are examined. Swept-area method was used for biomas estimation. Commercial bottom trawlers Data from 52 bottom trawl surveys are considered between 2009 and 2010.
3 2/17/2012
Ratio of elasmobranches in the total catch by trawling in the Bay of Iskenderun
Others 77%
Others Elasmobranches
Elasmobranches 23%
In regard to total stock biomass estimates, elasmobranches constituted 23 percent (190,06 kg/km2) of total biomass (650,715 kg/km2) in the Iskenderun Bay.
Raja clavata, Dasyatis pastinaca Gymnura altavela
showed high occurrence of the whole biomass of the elasmobranches
4 2/17/2012
Shark species, Squatina squatina, Mustelus mustelus, Scyliorhinus stellaris, Scyliorhinus canicula, Galeus melastomus, represented low percents of the whole biomass of the elasmobranches respectively.
The other species, Raja oxyrinchus, Rhinobatos rhinobatos, Raja miraletus, Torpedo marmorata, Torpedo torpedo comprised 7.6, 7.5, 0.4, 0.2, 0.1 percents of total biomass of the elasmobranches respectively.
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Distribution and amont of catch of Elasmobranche species in the Iskenderun Bay
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Seasonal Distribution of total catch of Elasmobranches
The ratio of elasmobranches cought by trawling during autumn, 2009-2010 in the total catch
Others 82% Others Elasmobranches Elasmobranches 18%
A total 182 kg/km2 of elasmobranches were collected in İskenderun Bay, representing 18% of the total biomass in autumn
7 2/17/2012
The ratio of elasmobranches cought by trawling during winter, 2009-2010 in total catch
Others 70%
Others Elasmobranches
Elasmobranches 30%
The eleasmobranches represent 30% of the total biomass in winter. Total biomas was being 864 kg/km2 of which elasmobranches comprise 259 kg/km2
The ratio of elasmobranches cought by trawling during spring, 2009-2010 in total catch
Others 64%
Others Elasmobranches
Elasmobranches 36%
The eleasmobranches represent of 36% of the total biomass in spring. Total biomas was being 434 kg/km2 of which elasmobranches comprise 155 kg/km2
8 2/17/2012
The ratio of elasmobranches cought by trawling during summer, 2009-2010 in total catch
Others 84%
Others Elasmobranches
Elasmobranches 16%
The eleasmobranches represent of 16% of the total biomass in summer.
Total biomas was being 1038 kg/km2 of which elasmobranches comprise 162 kg/km2 of that in İskenderun Bay.
Seasonal distribution of elasmobranches in the Iskenderun Bay
100% 18 16 30 80% 36
60% Elasmobranches 40% 82 84 Others 70 64 20%
0% Autumn Winter Spring Summer
Total catch of fish were 843, 605, 279, 876 kg/km2, of which elasmobranches species constitute 183, 259, 155, 162 kg/km2 in autumn, winter, spring and summer respectively.
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Seasonal distribution of some Elasmobranche species
Seasonal biomass of Gymnura altavela
41 40 39 38
37 kg/km2 36 35 34 Autumn Winter Spring Summer
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Seasonal biomass of Rhinobatos rhinobatos
35 30 25 20
15 kg/km2 10 5 0 Autumn Winter Spring Summer
Seasonal biomass of Dasyatis pastinaca
160 140 120 100 80
kg/km2 60 40 20 0 Autumn Winter Spring Summer
11 2/17/2012
Seasonal biomass of Torpedo marmorata
0,9 0,8 0,7 0,6 0,5 0,4 kg/km2 0,3 0,2 0,1 0 Autumn Winter Spring Summer
Seasonal biomass of Raja miraletus
0,9 0,8 0,7 0,6 0,5 0,4 kg/km2 0,3 0,2 0,1 0 Autumn Winter Spring Summer
12 2/17/2012
Seasonal biomass of Mustelus mustelus
3 2,5
2 1,5 kg/km2 1
0,5 0 Autumn Winter Spring Summer
Seasonal biomass of Torpedo torpedo
0,25
0,2
0,15
kg/km2 0,1
0,05
0 Autumn Winter Spring Summer
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Depth distribution of Elasmobranches trawled in the Iskenderun Bay
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Single or sporadic captures were also recorded for; Isurus oxyrinchus Carcharhinus plumbeus Carcharhinus altimus Oxynotus centrina Raja radula
Isurus oxyrinchus
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Carcharhinus plumbeus
Carcharhinus altimus
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Oxynotus centrina
Raja radula
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Rhinoptera marginata
Pteromylaeus bovinus
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Conservation status of Elasmobranches species caught as target and by-catch in commercial fisheries in Iskenderun Bay
Common Name Scientific Name Catch composition (%) Biyomass IUCN Global and (kg/km2) Regional Red List Status
Shortfin mako Isurus oxyrhinchus - - VU; CR in MDT
Sandbar shark Carcharhinus plumbeus - - NT; EN in MDT Blackmouth catshark Galeus melastomus 0.35 LC in MDT
Smouth-hound Mustelus mustelus 1.15 2.20 LC: VU in MDT Small spotted catshark Scyliorhinus canicula 0.37 0.70 LC in MDY
Nursehound Scyliorhinus stellaris - - NT in MDT Angular roughshark Oxynotus centrina - - VU; CR in MDT
Angelshark Squatina squatina 1.23 2.35 CR; CR in MDT Common stingray Dasyatis pastinaca 24.04 49.50 NT in MDT Spiny butterfly ray Gymnura altavela 20.38 41.96 VU; CR in MDT
Longnosed skate Dipturus oxyrinchus 7.62 14.50 NT; NT in MDT Thornback ray Raja clavata 34.17 64.95 NT; NT in MDT Brown ray Raja miraletus 0.36 0.70 LC in MDT Common guitarish Rhinobatos rhinobatos 7.51 14.28 EN; EN in MDT Common torpedo Torpedo torpedo 0.07 0.13 LC in MDT Spotted torpedo Torpedo marmorata 0.24 0.46 LC in MDT Lusitanian cownose Rhinoptera marginata - - NT in MDT ray Bull ray Pteromylaeus bovinus - - DD
Rough ray Raja radula - - DD in MDT
19 2/17/2012
Thanks . . .
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