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Identifier |
000454369 |
Title |
Spatial analysis of cetacean strandings in Greek seas in relation to fishing grounds, potential feeding grounds and surface circulation |
Alternative Title |
Χωρική ανάλυση των εκβρασμών ειδών κητωδών σε σχέση με αλιευτικά και πιθανά διατροφικά πεδία καθώς και με τη θαλάσσια κυκλοφορία στις ελληνικές θάλασσες |
Author
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Ανδριώτης, Εμμανουήλ Σ.
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Thesis advisor
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Τσερπές, Γεώργιος
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Reviewer
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Γιαννουλάκη, Μαριάννα
Σωμαράκης, Στυλιανός
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Abstract |
Cetacean strandings are a phenomenon that is observed on the coasts and serves as an
indicator of cetacean mortality in the sea. Reasons for direct human-induced cetacean mortality
include entanglement in fishing gear (by-catch), intentional killing (shooting, wounding), collision
with boats/vessels, ingestion of macroplastics, noise pollution from military sonars/seismic
surveys. A small percentage of dead cetaceans wash up on beaches and are recorded, which
depends on many factors (distance from the coast, marine traffic, morphology and accessibility of
the coast) that are often difficult to estimate.
The purpose of this study is to investigate the distribution of cetacean strandings in Greek
waters and their relationship with coastal fishing and marine traffic. A total of 1378 strandings of
9 cetacean species were studied, during the period 2010-2021, using the stranding database of the
Hellenic Center for Marine Research (HCMR). Kernel density estimate maps were created to
identify spatial hotspots of strandings by species and cause of death. Generalized additive models
(GAMs) were developed to explore the relationship between strandings and coastal fishing and
potential feeding areas. In a stranding hotspot area of particular interest, the possible origin of the
dead animal was estimated using the stochastic ensemble trajectory model, Leeway, which
estimates the movement of objects on the water surface under the effect of wind and current.
The study showed significantly clustered spatial distributions for both total cetacean
strandings and when 4 species of cetaceans were examined separately, revealing the existence of
hotspot areas in the study region. Generalized additive models demonstrated a possible positive
relationship between stranding events and the extent of fishing grounds, as well as the significant
role of the coastline in the recording of stranding events. Finally, possible estimates were made for
the potential origin of strandings in the Pagasitikos gulf and surrounding areas using the Leeway
model.
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Language |
English |
Subject |
GAMs |
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Hotspot analysis |
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Trajectory models |
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Εκβρασμοί |
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Κητώδη |
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Μοντέλα |
Issue date |
2023-03-24 |
Collection
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School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
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Type of Work--Post-graduate theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/a/b/a/metadata-dlib-1678975163-195580-15895.tkl
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Views |
487 |