Measurement, management and mitigation of operational interactions between the South Australian Sardine Fishery and short-beaked common dolphins (Delphinus delphis)

2008 ◽  
Vol 141 (11) ◽  
pp. 2865-2878 ◽  
Author(s):  
Derek J. Hamer ◽  
Tim M. Ward ◽  
Richard McGarvey
Keyword(s):  
The South ◽  
Delphinus Delphis ◽  
Common Dolphins

Injuries, healing and management of common dolphins (Delphinus delphis) in human-impacted waters in the south Iberian Peninsula

2020 ◽  
Vol 100 (2) ◽  
pp. 315-325
Author(s):  
Liliana Olaya-Ponzone ◽  
Rocío Espada ◽  
Estefanía Martín Moreno ◽  
Isabel Cárdenas Marcial ◽  
José C. García-Gómez
Keyword(s):  
Iberian Peninsula ◽  
Healing Process ◽  
Local Population ◽  
Survival Rates ◽  
Whale Watching ◽  
The South ◽  
Delphinus Delphis ◽  
Photo Identification ◽  
Type Of Injury ◽  
Common Dolphins

AbstractThis study focuses on the dolphins populating the water between Gibraltar and Algeciras in the south Iberian Peninsula, an area subjected to pressure due to high human activity. The area is considered an important feeding and breeding ground for common dolphins (Delphinus delphis). Due to the degree of residence of some specimens, and the large gap in knowledge about the evolution of wounds in D. delphis specimens with lacerations, this work sought to perform the following analyses: identify lacerated individuals; characterize sequences of ‘before – during – after’ with respect to the occurrence of lacerations; and associate the type of injury with its severity. This work will inform future studies by expanding a database on injured individuals and contribute to periodical monitoring of specimens that frequent these geographic areas. Between 2013 and 2017, we were able to track the healing process of five injured individuals of common dolphins from a whale-watching platform thanks to photo identification. The animals exhibited fresh external wounds from different sources. In the majority of individuals, the wound-healing processes lasted 3–21 weeks. The frequency with which sightings are made and knowledge about the local population will help track injured animals, follow their wound evolution, and document their survival rates. The documented injuries inflicted by human interactions described in this paper may include fishing interactions and propeller strikes, probably as a consequence of the high intensity of recreational fishing and whale-watching activities in the area.

scholarly journals Quantification of interactions between the Portuguese sardine purse-seine fishery and cetaceans

2015 ◽  
Vol 72 (8) ◽  
pp. 2438-2449 ◽  
Author(s):  
Ana Marçalo ◽  
Isidora Katara ◽  
Diana Feijó ◽  
Helder Araújo ◽  
Isabel Oliveira ◽  
...  
Keyword(s):  
Total Mortality ◽  
Purse Seine ◽  
Annual Number ◽  
Common Dolphin ◽  
The South ◽  
Delphinus Delphis ◽  
The North ◽  
Common Dolphins ◽  
Purse Seine Fishery ◽  
Purse Seining

Abstract Interactions between cetaceans and the purse-seine fishery operating along the whole Portuguese continental coast were studied based on on-board observations from 2010 to 2011. Cetacean presence and mortality were estimated and characteristics under which interactions were most likely to occur were identified. Observations were made on 163 fishing trips (0.7% of the average annual number of fishing trips) and 302 fishing operations/hauls. Cetaceans were present during 16.9% of fishing events; common dolphins (Delphinus delphis) accounted for 96% of occurrences, mostly overnight in summer and early autumn. Regression models showed that cetacean presence during a fishing set was significantly (p < 0.05) associated with sardine catches, effort, and latitude/longitude. Encirclement and mortality occurred in 2.3 and 1.0% of fishing events, respectively. Encircled species were the common dolphin, bottlenose dolphin (Tursiops truncatus), and harbour porpoise (Phocoena phocoena), but only common dolphin showed mortality (three individuals); raised to fleet level, estimated total mortality rates of common dolphins were 69 (95% CI 37–110) in the north and 91 (95% CI 55–165) in the south for 2010 and 78 (95% CI 47–140) in the south only for 2011. The estimated annual mortality rate due to purse seining is 113 (95% CI 3–264) common dolphins, which is ∼0.63% of the current most optimistic estimate of population size for the Portuguese fishing area (SCANS II). The wide confidence limits, as well as variation between years, reflect low observer coverage, emphasizing the need for increased monitoring to cover gaps in the spatial and seasonal distribution of observer effort and provide reliable estimates of bycatch.

scholarly journals Long-term dietary segregation of common dolphins Delphinus delphis in the Bay of Biscay, determined using cadmium as an ecological tracer

2005 ◽  
Vol 305 ◽  
pp. 275-285 ◽  
Author(s):  
V Lahaye ◽  
P Bustamante ◽  
J Spitz ◽  
W Dabin ◽  
K Das ◽  
...  
Keyword(s):  
Bay Of Biscay ◽  
Delphinus Delphis ◽  
Common Dolphins

scholarly journals Cetaceans using the marine protected area of "Parque Estadual Marinho da Laje de Santos", Southeastern Brazil

2017 ◽  
Vol 65 (4) ◽  
pp. 605-613 ◽  
Author(s):  
Marcos Cesar de Oliveira Santos ◽  
Giovanna Corrêa e Figueiredo ◽  
Marie-Francoise Van Bressem
Keyword(s):  
Protected Area ◽  
Marine Protected Area ◽  
Unknown Origin ◽  
Mantel Test ◽  
Southeastern Brazil ◽  
Common Dolphin ◽  
Balaenoptera Acutorostrata ◽  
Stenella Frontalis ◽  
Delphinus Delphis ◽  
Common Dolphins

Abstract The aim of this study was to evaluate the presence of cetaceans in the waters surrounding the Marine Protected Area (MPA) known as “Parque Estadual Marinho da Laje de Santos (PEMLS)”, placed in coastal waters at the southeastern coast of Brazil. Boat-based surveys were conducted once a month from June 2013 to June 2015. A specific transect was followed to cover the area of the quoted MPA, as well as its borders. A total of 24 boat-surveys rendered 18 sightings of cetacean groups of the following species: Atlantic spotted dolphin (Stenella frontalis) (12), rough-toothed dolphin (Steno bredanensis) (2), common dolphin (Delphinus delphis) (1), Bryde’s whale (Balaenoptera edeni) (2) and common minke whale (Balaenoptera acutorostrata) (1). Sightings of S. frontalis, the commonest sighted species, was positively correlated with water depth (Mantel test; r = 0.8072; p < 0.05). Photoidentified individuals moved back and forth to inner and outer areas of the MPA, remaining in the area throughout the 2-year survey. “Paisley” cutaneous marks of unknown origin were reported in two common dolphins for the first time in local waters. As the PEMLS has been used as an important spot for SCUBA divers, it is recommended that cetacean sightings could still be gathered in a future partnership, as well as using the acoustics tool to detect their presence when researchers are not in the field.

scholarly journals Short-term effects of tourism on the behaviour of common dolphins (Delphinus delphis) in the Azores

2017 ◽  
Vol 98 (5) ◽  
pp. 1187-1196 ◽  
Author(s):  
Arianna Cecchetti ◽  
Karen A. Stockin ◽  
Jonathan Gordon ◽  
José M.N. Azevedo
Keyword(s):  
Transition Probabilities ◽  
High Energy ◽  
Tourism Industry ◽  
Common Dolphin ◽  
Short Term ◽  
Delphinus Delphis ◽  
Critical Activity ◽  
Time Required ◽  
Common Dolphins

Short-term measures of behavioural responses of cetaceans to tourism operations have been used in many studies to interpret and understand potential long-term impacts of biological importance. The short-beaked common dolphin (Delphinus delphis) is the species most frequently observed in the Azores and constitutes an important component of the marine mammal tourism industry in this region. This study investigated the potential effects of tour boats on the behaviour of common dolphins off São Miguel, Azores, with particular focus on the changes in activity budget and the time required to resume activities after a tour boat interaction. Behavioural data were collected from land using a group focal-follow methodology. Markov chains were applied to analyse control and interaction sequences and to assess behavioural transition probabilities in both scenarios. In the presence of tour boats, dolphins significantly reduced the time spent foraging and increased the time engaged in other high energy activities. Dolphins also took significantly longer to resume feeding after an interaction occurred. The average bout length varied significantly between control and interaction scenarios, with foraging bouts being shorter during tour boats interactions. The results presented have management implications since feeding is a biologically critical activity. Disruption of foraging behaviour could lead to a decrease in energy intake for this population. With cetacean tourism likely to increase in the future, a precautionary approach to issuing new licences is advisable and any expansion would warrant an appropriate monitoring programme.

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