Giovanni Bearzi

Dolphin Biology and Conservation

The scientific study of death across animal taxa—comparative thanatology—investigates how animals respond behaviourally, physiologically and psychologically to dead conspecifics, and the processes behind such responses. Several species of cetaceans have been long known to care for, attend to, be aroused by, or show interest in dead or dying individ...

Some mammalian species that have not succumbed to pervasive human impacts and encroachments have managed to adapt to certain types of human activities. Several odontocetes have modified their behavior to persist, and in some cases even prosper, in human-altered riverine, coastal, and oceanic habitat. Examples include cooperation with fishers to cat...

Humanity’s self-ordained mandate to subdue and dominate nature is part of the cognitive foundation of the modern world—a perspective that remains deeply ingrained in science and technology. Marine biology has not been immune to this anthropocentric bias. But this needs to change, and the gaps between basic scientific disciplines and the global cons...

Some populations of marine mammals (particularly odontocete cetaceans, and pinnipeds) have responded to the expansion of fisheries by modifying their behaviour to take advantage of the foraging opportunities provided by fishing. This has led to interactions that include forms of “depredation”, referring to the removal of, or damage to, marketable o...

The Adriatic Sea is one of the areas most exposed to trawling, worldwide. We used four years (2018–2021) and 19,887 km of survey data to investigate factors influencing daylight dolphin distribution in its north-western sector, where common bottlenose dolphins *Tursiops truncatus* routinely follow fishing trawlers. We validated Automatic Identifica...

Descriptions of social structure of a species or population help to understand the processes that shaped its social system, and such knowledge can be valuable in terms of conservation planning. While striped dolphins *Stenella coeruleoalba* are among the most abundant cetacean species worldwide, and the most abundant in the Mediterranean Sea, their...

1. Group membership is a key attribute of animal societies and central to the study of social structure in several taxa. However, social structure analyses are sensitive to the way data are collected and associations defined. 2. In this study, a time–space method was used to investigate the social structure of common bottlenose dolphins Tursiops tr...

A number of seabird species have been known to peck, displace, and ingest various plastic items including expanded polystyrene, for reasons that remain largely conjectural. Ingestion of polystyrene parts potentially causes lethal or sublethal effects on birds. Pecking can also result in the damage of polystyrene items, resulting in increased market...

Between the 16th and 20th century, small cetaceans (particularly dolphins) were killed in large numbers off the coasts of modern Europe and North Africa, due to perceived competition with fisheries. Here, dolphins were long considered as pests responsible for reduced fish catches and damage to fishing gear. Such conflict was particularly acute betw...

IUCN Red List assessment of striped dolphins *Stenella coeruleoalba* in the Gulf of Corinth, Greece (Mediterranean Sea)

Several populations of odontocete cetaceans, including at least 19 species, have modified their behavior and adapted to foraging in association with trawlers. We review information on odontocete interactions with different types of trawlers across 13 Food and Agriculture Organization fishing areas around the world. We also review knowledge gaps, th...

ABSTRACT — As finfish cage aquaculture expanded in the coastal waters of the Mediterranean Sea, several communities of common bottlenose dolphins *Tursiops truncatus* came into contact with this type of gear. Some animals or communities learned to take advantage of the new foraging opportunities provided by aquaculture facilities, where wild prey t...

Several populations of odontocete cetaceans, including at least 19 species, are known to forage and feed in association with trawlers. We reviewed information on odontocete interactions with different kinds of trawlers across 13 FAO fishing areas around the world. We also identified knowledge gaps, effects on odontocete ecology, distribution, behav...

Group membership is an important attribute of animal societies. Here, we investigated the social organisation of striped dolphin *Stenella coeruleoalba* through a relatively novel method based on time and space criteria associated with geo-referenced identification photographs. Instead of adopting traditional group definitions, we considered indivi...

https://www.iucnredlist.org/species/189865869/189865884

Stable isotope compositions of carbon and nitrogen (expressed as δ ¹³ C and δ ¹⁵ N) from the European common cuttlefish ( Sepia officinalis ) were measured in order to evaluate the utility of using these natural tracers throughout the Northeast Atlantic Ocean and Mediterranean Sea (NEAO-MS). Mantle tissue was obtained from S. officinalis collected...

Within just one human lifetime, the underlying motivation to conserve whales, dolphins and porpoises has shifted from being purely practical and anthropogenic to something much broader, reflecting a desire to protect populations as well as individual animals. In European waters, cetacean conservation currently tends to focus on direct and obvious t...

The Mediterranean Sea is one of the world's seas most affected by human activities. In this region, concern for the conservation status of the common dolphin *Delphinus delphis* has been expressed since the 1990s. Systematic culling campaigns and intentional takes represented a major cause of mortality between the 1870s and the 1970s. These killing...

Focusing on the threats that cause direct mortality to whales and dolphins is not sufficient. Indeed, important threats are indirect, and originate from human impacts that are global and pervasive. These include calamities such as the widespread loss of marine biodiversity caused by over-exploitation and destructive fishing gear, ever-increasing an...

Una presentazione video in italiano (20 min 56 sec) basata sull'articolo: Bearzi G (2020) Marine biology in a violated planet: from science to conscience. Ethics in Science and Environmental Politics 20, 1-13. https://www.int-res.com/abstracts/esep/v20/p1-13/

https://www.iucnredlist.org/species/134817215/50352620

1. The Adriatic Sea is one of the Mediterranean areas most heavily impacted by fishing and other human stressors. The northern part of the basin has been certified as an Important Marine Mammal Area because of the regular occurrence of common bottlenose dolphins, Tursiops truncatus. 2. Boat surveys, totalling 76 days at sea and 10,711 km of naviga...

• Many species and populations of odontocetes have modified their behaviour to take advantage of feeding opportunities provided by fishing activities, with depredation of fishing gear being the most common type of adaptation. • The northern Adriatic Sea has been identified as an important marine mammal area because of a regular occurrence of common...

A shortened and amended version of the article: Bearzi G. (2020) Marine biology on a violated planet: from science to conscience. Ethics in Science and Environmental Politics 20:1-13. https://doi.org/10.3354/esep00189

Natural markers (δ13C and δ18O stable isotopes) in the cuttlebones of the European common cuttlefish (Sepia officinalis) were determined for individuals collected across a substantial portion of their range in the Northeast Atlantic Ocean (NEAO) and Mediterranean Sea. Cuttlebone δ13C and δ18O were quantified for core and edge material to characteri...

Fewer than 50 mature individuals exist within this subpopulation. The Common Dolphin Gulf of Corinth subpopulation was estimated to contain an average of 22 (95% CI 16–32) individuals (Santostasi et al. 2016). Even assuming an upper CI limit and 100% being mature individuals (i.e. complete absence of immatures), the abundance of mature individuals...

Hybridization affects the evolution and conservation status of species and populations. Because the dynamics of hybridization is driven by reproduction and survival of parental and admixed individuals, demographic modelling is a valuable tool to assess the effects of hybridization on population viability, e.g., under different management scenarios....

Marine megafauna has always elicited contrasting feelings. In the past, large marine animals were often depicted as fantastic mythological creatures and dangerous monsters, while also arousing human curiosity. Marine megafauna has been a valuable resource to exploit, leading to the collapse of populations and local extinctions. In addition, some sp...

Mixed species groups (MSG) occur among different mammalian species, ranging from related species to species belonging to different orders. MSG may enhance foraging and predator avoidance, or provide social benefits. These advantages, however, may not be equally distributed between the participating species. Although the habitat of Mediterranean com...

1. Understanding marine mammal distributions is essential for conservation, as it can help identify critical habitat where management action can be taken. The semi-enclosed Gulf of Corinth, Greece, has been identified as an Important Marine Mammal Area by the International Union for Conservation of Nature (IUCN) Marine Mammal Protected Areas Task F...

The National Marine Park of Alonissos, Northern Sporades (NMPANS) is the largest Marine Protected Area in Greece (2220 km2). In the summers (June – September) of 2013–2015 and 2017–2018, we conducted boat-based surveys to study the poorly-known cetaceans of the NMPANS. Across 79 survey days and 2565 km of navigation, we encountered four species: co...

Bearzi G., Bonizzoni S. 2018. Interazioni fra delfini e pesca in Adriatico settentrionale. Resoconto tecnico. Consulenza e supporto tecnico-logistico per Università degli Studi di Padova. 26 pp.

The success of a marine protected area depends on knowledge of distribution and habitat use by the species it aims to protect. The Gulf of Corinth, a 2400 km2 semi-enclosed embayment in Greece, has been identified as an Important Marine Mammal Area (IMMA) based on the satisfaction of all four selection criteria for IMMA status. In this area, three...

Laterally bent dorsal fins are rarely observed in free-ranging populations of cetaceans, contrary to captivity, where most killer whale Orcinus orca adult males have laterally collapsed fins. This topic has been poorly explored, and data/information on its occurrence and possible causes are limited. The present study: (i) undertakes a review of the...

The sharing of marine mammal data is a worthwhile practice, but there are caveats. Data interpretation may be difficult, sometimes resulting in misleading information or inappropriate formulation of research questions. Here, we point out some of the challenges when dealing with shared marine mammal datasets. We emphasize the importance of collectin...

Action Plan for Marine Mammals in Israel, 2017-2022 — SUMMARY — The Mediterranean waters of Israel cover a sea surface of approximately 26,000 km2. Israel also has a small 14 km window open to the Red Sea, at the northwestern tip of the Gulf of Aqaba/Eilat. These waters host a considerable variety of marine mammals: most of the cetacean species kno...

While the Mediterranean Sea has been designated as a Global Biodiversity Hotspot, assessments of cetacean population abundance are lacking for large portions of the region, particularly in the southern and eastern basins. The challenges and costs of obtaining the necessary data often result in absent or poor abundance information. We applied captur...

Estimates of abundance of striped dolphins over the 5 years of the study. The line represents the regression of abundance over time. The determination coefficient (R squared) and the significance level are reported. (JPEG)

Dataset used for striped and common dolphin CR analysis. (TXT)

Robust design models applied to the bottlenose dolphin dataset. The models are ranked by lowest QAICc, number of parameters (npar) and difference in QAICc scores (ΔAICc). QAICc weights indicate strength of evidence for a given model. S(year) = yearly variation in apparent survival; S(.) = no variation in apparent survival; p(year.month) = yearly an...

Estimates of abundance of bottlenose dolphins. Year 2011 is omitted from the regression because the estimate was judged non-reliable (see Results section). The line represents the regression of abundance over time. The determination coefficient (R squared) and the significance level are reported. (JPEG)

Dataset used for bottlenose dolphin CR analysis. (TXT)

Example of R script used for performing CR analysis on both datasets. (TXT)

List of survey days used to build the capture-recapture matrix. The whole study area was covered at least once per secondary occasion (months). (PDF)

Total number of sampling days with bottlenose dolphin encounters. The days used to build the capture-recapture matrix are highlighted in bold. (PDF)

Robust design models applied to the striped and common dolphin dataset. The models are ranked by lowest QAICc, number of parameters (npar) and difference in QAICc scores (ΔAICc). QAICc weights indicate strength of evidence for a given model. S(year) = yearly variation in apparent survival; S(.) = no variation in apparent survival; p(year.month) = y...

The Gulf of Corinth is a 2400-km² semi-enclosed inland system (a mediterraneus) in central Greece. Its continental shelf areas, steep bottom relief, and waters up to 500–900 m deep offer suitable habitat to neritic and pelagic species. We used photographic capture–recapture, distribution modelling, and direct observations to investigate the abundan...

Oceanomare Delphis Onlus (Italy), BICREF (Malta) and OceanCare (Switzerland), jointly organized the 1st International Workshop on short‐beaked common dolphin (Delphinus delphis, Linneaus 1758), which took place in Ischia, between the 13th and the 15th of April, in order to assess the status of the Mediterranean population, understand the major thre...

Santostasi N.L., Bonizzoni S., Bearzi G., Eddy L., Gimenez O. 2016. Revised abundance estimates of striped and short-beaked common dolphins in the Gulf of Corinth, Mediterranean Sea. Proceedings of the 30th Annual Conference of the European Cetacean Society. Funchal, Madeira, 14-16 March 2016.

In the Gulf of Corinth (GOC), a 2,400 km2 semi-­enclosed embayment in Greece, three odontocete species occur within 11 km of the nearest coast. Striped dolphins Stenella coeruleoalba are abundant (1,420 animals, 95%CI 1,275-­1,566) and live in mixed groups with 26 short-­‐beaked common dolphins Delphinus delphis (95%CI 13-­39) and 58 individuals of...

Species-specific diet analysis is fundamental for the study of many ecological processes. In the marine environment, however, the direct obser-vation of foraging such as ingestion events can be difficult, which is why indirect methods have been developed. Between 2002 and 2009, we used a non-invasive and easily applicable method to investigate the...

Santostasi N.L., Bearzi G., Bonizzoni S., Bosquez J., Da Silveira M.F., Marcum E., Piwetz S., Würsig B. 2015. Building a historic Texas bottlenose dolphin photo-identification catalog. Southeast and Mid-Atlantic Marine Mammal Symposium (SEAMAMMS), Virginia Beach, VA, March 27-29, 2015.

Finfish farms (FF) are known to aggregate wild fish, primarily because of large quantities of uneaten food lost from the cages. Complex substrate, increased nutrient levels and provision of fish-feed produce trophic enrichment and can attract dolphin prey. Common bottlenose dolphins Tursiops truncatus were observed foraging in the proximity of FF i...

Santostasi N.L., Bonizzoni S., Bearzi G. 2015. Optimizing abundance estimates of striped dolphins in the Gulf of Corinth, Greece. Proceedings of the 29th Annual Conference of the European Cetacean Society. St. Julians, Malta, 23-25 March 2015.

1. Common bottlenose dolphins Tursiops truncatus interact with fish farms in the Mediterranean Sea. These interactions were investigated in a Greek bay by incorporating multiple geographic, bathymetric, oceanographic, and anthropogenic variables. 2. Generalized additive models (GAMs) and generalized estimation equations (GEEs) were used to describe...

Santostasi N.L., Bonizzoni S., Bearzi G. 2014. Striped dolphin abundance in the Gulf of Corinth, Greece: dataset simulations help improve sampling design. International Marine Conservation Congress, Glasgow, Scotland, 14-18 August 2014.

Bonizzoni S., Santostasi N.L., Würsig B., Bearzi G. 2014. Bottlenose dolphin abundance in the Northern Evoikos Gulf, Greece. Proceedings of the 28th Annual Conference of the European Cetacean Society. Liège, Belgium, 5–9 April 2014.

Rapid progress and affordability of photographic technology with increasing improvements in image resolution have facilitated advancements in efficiency and alternative approaches in data collection for marine mammals. We report these recent improvements by comparing marine mammal photographs taken during 2008-2013 aerial surveys of 16 marine mamma...

Bonizzoni S., Furey N., Pirotta E., Valavanis V.D., Würsig B., Bearzi G. 2013. Modelling interactions between fish farms and bottlenose dolphins in a Mediterranean embayment. Proceedings of the 27th Annual Conference of the European Cetacean Society. Setúbal, Portugal, 8–10 April 2013.

This paper contributes an updated and detailed review of fin whale mortality events in the Adriatic Sea, encompassing four centuries. A total of 17 events, all referring to single animals, were validated through a content review of historical and recent information. Mortality events in the area mostly involved dead animals (N = 12; 70.6%), with 2 w...

The short-beaked common dolphin Delphinus delphis has declined throughout the Mediterranean and this population has been classified as Endangered in the IUCN Red List. The Gulf of Corinth is one of the few eastern Mediterranean areas where these animals still occur. However, only 28 (95% CI=11-73) common dolphins live in the Gulf, as compared with...

Bonizzoni S., Bearzi G., Würsig B. 2012. Distribution of common bottlenose dolphins Tursiops truncatus in the Northern Evoikos Gulf, Greece. Texas A&M University Research Symposium, Galveston, TX (USA), 25-26 April 2012.

While short-beaked common dolphins are often regarded as highly mobile animals, their movements and ranging patterns are poorly known and no long-distance movements have been documented through photo-identification of individuals. We report the long-distance movement of a naturally marked individual, encompassing a minimum of 1000 km across the Ion...

The species is widespread and abundant (with current population estimates around 300,000) and there have been no reported population declines or major threats identified. http://www.iucnredlist.org/details/full/11140/0

The species is widespread and abundant (with current population estimates exceeding 100,000) and there have been no reported population declines or major threats identified. http://www.iucnredlist.org/details/full/11142/0

Lissodelphis borealis is widespread and abundant, with population estimates in the high tens to low hundreds of thousands throughout their North Pacific range. High levels of bycatch during the 1970s and 1980s are estimated to have reduced their population size within the last three generations by an unknown amount, but the most realistic scenarios...

The species is widespread, but abundance has not been estimated for the mid- and east Atlantic (and where abundance estimates do exist for other regions, these are low) and there are bycatches and directed takes in West Africa of unknown, but likely escalating, scale. http://www.iucnredlist.org/details/full/20730/0

The eastern Spinner Dolphin population has ceased to decline but shows no clears signs of recovery. While there are few estimates of abundance and takes available in regions other than the eastern tropical Pacific, they are taken throughout their range by a diverse number of direct and indirect fisheries; some of these indirect takes may evolve int...

All bottlenose dolphins around the world were previously recognized as T. truncatus, but recently the genus has been split into two species: T. truncatus and T. aduncus (the smaller Indo-Pacific Bottlenose Dolphin – Wang et al. 1999, 2000a,b). However, the taxonomy of bottlenose dolphins is confused, due to geographical variation, and it is very po...

The species is widespread and abundant (with current population estimates around 150,000) and there have been no reported population declines or major threats identified. http://www.iucnredlist.org/details/full/20738/0