Search Results (6)

The common dolphin, Delphinus delphis, is the most abundant cetacean species along the western Iberian Peninsula and faces many anthropogenic threats, with bycatch being the most impactful. Its preferred prey, sardine (Sardina pilchardus), has shown fluctuating abundance over the past decade, potentially influencing dolphin distribution. This study provides the first insights into common dolphin distribution along the western Iberian coast, using sighting data from vessel research surveys (2005–2020) to identify hotspot areas while accounting for monthly and seasonal distributions overlapping with sardine abundance. Common dolphin hotspots were located along the central–western and southern Portuguese mainland coasts, coinciding with important fishing ports, oceanographic features, and sardine juvenile habitats. Furthermore, during 2013–2016, common dolphins were observed significantly farther from the coast, coinciding with a period of particularly low coastal sardine biomass. However, GAM analysis indicated that the relationship between sardine biomass and the distance of common dolphins was not significant. This study highlights the major common dolphin hotspots and presents the most comprehensive temporal and distribution maps of the common dolphin along the western Iberian coast, particularly in response to sardine availability. These results can be used by managers to inform conservation measures and for the sustainable management of the Portuguese sardine purse seine fishery fleet, which interacts the most with the species. Full article

The study explores the interactions between dolphins and Cypriot fisheries, emphasizing the economic impact and fisher perceptions through data collected from structured interviews with small-scale and large pelagic fishers. The research documents frequent dolphin interactions, impacting catch and gear in both fishing sectors. Reported financial losses and gear damage highlight a significant economic burden, with annual losses averaging EUR 6144 for small-scale and EUR 29,882 for large pelagic fishers. Efforts to mitigate these interactions, such as using acoustic deterrents, have shown mixed results, reflecting dolphins’ adaptability to human activity. While some fishers use deterrents, others remain hesitant due to cost and inconsistent efficacy. The study underscores the need for improved, sustainable solutions that integrate fisher input to enhance acceptance and effectiveness. Findings suggest that dolphins are increasingly relying on fishing activities as a foraging strategy, aligning with broader trends in the Mediterranean. In the context of EU Directive 2014/89/EU, the study integrates ecological considerations and socioeconomic impacts to ensure balanced marine management strategies. This work emphasizes the complexity of human–wildlife conflicts in marine environments, suggesting that further research and collaboration with fishers are essential to developing adaptive strategies that balance conservation with the economic needs of local fishing communities. Full article

Data collected by C. Re. Di. Ma over a 3-year period (2020–2022) were considered to assess anthropic pressure on cetaceans living in the Ligurian sea. Out of a total of 37 stranded cetaceans, a complete post mortem examination was performed on 23 cases. Of these, 14 were further selected considering at least one of these conditions: (i) confirmed, probable, or suspected interaction with fishing activities through the application of a standardized diagnostic framework (7/14; 50%), (ii) toxicological stress through the evaluation of OCs hazardous levels (14/14; 100%), and (iii) terrestrial pathogen-associated disease (systemic infection and/or associated lesions) (7/14; 50%). For 9 animals out of a total of 14 selected, the cause of death was classified as natural (6/14; 42,8%), anthropic (3/14; 21,4%), or not determined (5/14; 35,7%) based on gross and histological pathology and ancillary testing. These findings extend our knowledge of the anthropic pressure to which cetaceans stranded along the Ligurian coastline are subjected from a multidisciplinary point of view. Full article

Interactions between fishing and dolphins can be detrimental, since on one hand dolphins can be lethally entangled by nets and trawls, and on the other dolphins can predate fish caught by nets. For dolphins, this interaction can be dangerous as they can be wounded or accidentally killed; for fishers, the predation of their catch results in economic losses due to reduced quantity and/or quality of catches and damage to fishing gear. During July and November 2020, we surveyed the “dolphin–fisheries conflict” through compiling 209 fisher interviews from nine locations in Italy and Croatia. Fishers mentioned the common bottlenose dolphin (Tursiops truncatus) as the species primarily interacting with fishing, with the major issue being catch damage by predation. The interaction probability varied among gears and seasons, with some fishing activities (e.g., passive nets) more affected than others (e.g., bottom trawls), especially in terms of economic loss (1000–10,000 €/year on average). More than 70% of the fishers claimed that dolphin populations have increased over the last 10 years, in different degrees and based on different areas. Dolphin bycatch rates are generally low; however, 34.6% of respondents reported having captured at least one dolphin during their career. The fishers’ attitude towards acoustic deterrents (“pingers”) as a mitigation measure revealed that few of them were aware of these devices or were using them. Full article

The selective retention of fish is a consequence of size and species-dependent fish behaviour during the trawling process. The observation of fish reactions to trawl gear is critical to understanding the behavioural mechanisms responsible for trawl selectivity and to develop future trawl gear for research. In demersal trawling, there is a need to develop more species-selective trawls to minimize discarding and bycatch in multispecies fisheries. This requires observational tools that can operate at depths and light levels encountered by the commercial fleets and with the ability to quantify the herding and capture efficiency by species and age groups of such gears. A range of optical and acoustic observation techniques has been developed over the past few decades to assist in these goals. Work with underwater cameras in fishing gear varies from the simple observation of the presence of certain species during capture to the study of the complex interactions of fishing gear and species during the trawling process. Previous work seems to show that there are different response patterns in the general behaviour of some fish species when entering a trawl. One of these behaviours is that the vertical preference in the trawl cavity differs between species. Several authors have complemented behavioural studies carried out at sea with experimental studies to further explore the interaction between fish and fishing gear. Some authors indicate that the vertical preferences of some fish species change as they move through the net towards the codend. This implies that behavioural selection can potentially change along the horizontal axis of the fishing net. A description of the bycatch (cetaceans, sharks, and skates) and fish behaviour within bottom trawling gear was given through the use of underwater cameras. The objective was to determine the most suitable fishing gear configurations to prevent the escape of the fishing catch during fishing trials carried out to test the operation of dolphin-exclusion devices and selective codends. The behaviours recorded by the cameras were classified into seven types of behaviour: orientation, reaction, resistance, re-entry, final entry, escape attempts, and panic reaction. Full article

Existing literature on dolphin-fisheries interaction focused on Greece reveals both an undeveloped area for research, but also a lack of relevant data in this field. Although imperative, relevant research has been slow on innovation and cooperation among universities, official bureaus, and NGOs that are obliged to work together as European and national laws dictate. Most of the research in this new field focuses on the interaction between marine mammals and local fisheries, suggesting that this relationship may be problematic for both parties since the former are being treated (at least occasionally) with brutality, while the latter try to deal with economic loss. Dolphins and fishermen operate within the same ecological niches for their survival, the main area of conflict being nutritious fish. Anthropological research on ethnic identity has long dealt with antagonistic relationships over resources between adjacent groups of people. Marine biologists’ research in Greece focuses on the human factor, and some of its shortcomings may well be seen as the result of limited, or an absence of, training in social sciences. This article attempts to draw from anthropological theory to shed light on a particular symbiosis between humans and dolphins. Multidisciplinary approaches gain ground in a wide range of research interests and seem to be fruitful in terms of theoretical and practical results. Full article