New record of the great white shark Carcharodon carcharias from Lampedusa

This new record confirms that the Central Mediter ranean, and Sicilian coasts in particular, still represent a key area for the population of Mediterranean white sharks, but also for other shark species (Bilecenoglu et al., 2013); in fact, 43% of all white shark sightings in the Italian seas (Micarelli et al., 2011) are from this area

Pojava parazita Otodistomum veliporum u štrcalu morskog psa drkovne (Dalatias licha)

The presence of the digenean Otodistomum veliporum is reported here for the first time as a parasite in the spiracle of a Mediterranean specimen of the kitefin shark Dalatias licha.Prvi put je zabilježena u znanstvenoj literaturi prisutnost parazita Otodistomum veliporum u štrcalu morskog psa drkovne Dalatias licha

Influence of Male Presence on the Socıal Structure of Lesser Spotted Dogfısh (Scyliorhinus canicula) Female Groups

Sexual segregation in the lesser spotted dogfish (Scyliorhinus canicula) is most likely driven by the female strategy of avoidance of the males, which causes the formation of female groups in the nooks and shelters on the seafloor. This strategy allows them to reduce the multiple events of male sexual advances, which are energetically expensive. In order to examine the existence of a social structure in female lesser spotted dogfish aggregations and the impact of the presence of males on them, we analyzed the structure of the social network and the temporal stability of the associations of two populations each one including five females. An easy insertion of the males in female population was made possible by the presence of a homogeneous initial social structure with quite weak bonds. The social structure is regulated by differences in the individual behaviour, resulting in different strength and stability of aggregations of conspecifics. The addition of the males produced a reduction of the Average Association Index and of the measures related to the populations’ network, strength of the associations and level of indirect connections of the individual. The presence of the males seems to have a greater effect on the individuals that are more weakly linked; while key individuals typically reduce their network values, but remain well integrated in the population; peripheral individuals have more variables values. This result indicates that relations exist between the sex, which is in contrast with the hypothesis of the female avoidance of males, which should produce strong and stable female groups. The actual knowledge of the behaviour and distribution of the Mediterranean lesser spotted dogfish does not prove the existence of a sexual segregation in this species. Based on the results we can assume that the home-ranges of females and males are not separated and that the male presence does not trigger a female aggregation mechanism. It is noteworthy that males have a destructive effect on the female associations, as these ones have shown a reduction of all the values. This might suggest that, in nature, the male presence and therefore the potential male sexual coercion may cause the spatial dispersion of the individuals of the population and reduce the cohesion of the group

Preliminary Observations on the Ability to Adapt To Salinity Changes in Nursehound Scyliorhinus Stellaris (Linnaeus, 1758) and Small Spotted Catsharks Scyliorhinus Canicula

Nursehound Scyliorhinus stellaris and small spotted catsharks Scyliorhinus canicula are frequently hosted in public aquaria and their husbandry is improving. The reproduction of this species in captive conditions is not difficult and juveniles are easily maintained in laboratory or in thematic tanks showed to the public. Data on juveniles are easily acquired in order to understand different aspects of their natural life and physiology. In two stages, during 2006 and 2010, six S. stellaris and three S. canicula juveniles were tested at different salinity levels under controlled conditions in order to understand their responses in terms of respiration rate to this stress. In fact this is a benthic species living at constant water quality parameters at approximately 70-100 meters deep

High levels of prevalence related to age and body condition: host-parasite interactions in a water frog Pelophylax kl. hispanicus

Host traits can significantly influence patterns of infection and disease. Here, we studied the helminths parasitizing the Italian edible frog Pelophylax kl. hispanicus, giving special attention to the relationship between parasites and host traits such as sex, snout vent length, weight and body condition. The helminth community was composed of seven species: three trematode species (Diplodiscus subclavatus, Gorgodera cygnoides, Pleurogenes claviger), three nematode species (Icosiella neglecta, Oswaldocruzia filiformis, Rhabdias sp.) and one acanthocephalan species (Pomphorhychus laevis ). We found that prevalence was positively correlated with snout-vent length and weight, but did not differ with body condition or sex. We found that prevalence and mean species richness increased with age. Our results show that abundance of Icosiella neglecta was positively correlated with higher values for host body condition. In fact, we found that high prevalence and mean species richness do not necessarily imply poorer body condition in the parasitized host. In conclusion, our results show that the helminth community in this taxon has great diversity, and this host-parasite system seems to be evolved to low levels of virulence, helminths maintaining a commensal relationship with this frog.his research was carried out with the approval of the “Ministero dell’Ambiente e della Tutela del Territorio (Direzione per la Protezione della Natura)”, permit number 2004/30911

Preliminary observations about white shark's (Carcharodon carcharias) discriminatory patterns during surface predatory activity and type of approach

The aim of the present study was to gather information on the behaviour of great white shark Carcharodon carcharias during surface predatory activities. According to the present results, vision plays an important role in feeding patterns and appears correlated to weather conditions

Evidence of Non-Random Social Interactions between Pairs of Bait-Attracted White Sharks in Gansbaai (South Africa)

Knowledge about the social behavior of sharks is a growing research field, but not many observations are available on the social interactions between pairs of sharks in the presence of passive surface bait and mainly related to aggregations. Between 2009 and 2018, in Gansbaai, South Africa, 415 white sharks were sighted, and 525 surface-generated social interactions were identified, exhibited by 169 different white sharks. The mean sighting rate was 0.91 (range 0.18–1.53) white sharks per hour. Eight patterns of social interaction were exhibited: swim by, parallel swim, follow/give way, follow, give way, stand back, splash fights, and piggyback. Non-random interactions occurred when pairs of specimens approached the passive surface bait, confirming that the white sharks made a real choice, showing a dominance hierarchy during the ten years of data collection. Evidence of non-random social interactions in the surface behavior of bait-attracted white sharks Carcharodon carcharias in Gansbaai’s transient population was the goal of this research

Behavioural responses of white sharks to specific baits during cage diving ecotourism

This study describes the effect of different baits on the attraction, surface behaviour and conditioning of white sharks Carcharodon carcharias during local ecotourism activities. The sightings, behaviours, and pictures used for photographic identification were obtained during August to November 2012-2014 onboard tourist boats in Guadalupe Island, Mexico. Four types of baits were used: (1) frozen bait; (2) frozen bait and natural chum; (3) fresh fish bait; and (4) mackerel bags. Data were analysed according to sex, maturity and the total of sharks using 6,145 sightings of 121 white sharks. The type of bait showed no significant difference on the effectiveness to attracting sharks. Ethological analysis showed that the type of bait had a significant effect on the shark's surface behaviour during its interactions with boats. Natural chum and fresh baits showed short term behavioural patterns constituted by increased number of violent interactions with the bait, while the frozen bait did not generate a defined behavioural pattern. Conditioning of white sharks was determined by the number of interactions and the consumption frequency of the bait. Fifty nine percent of sharks (n=41) showed no conditioning, 36% (n=25) showed a low risk and only 5% (n=3) were found to have a high risk of conditioning. The results suggest that current ecotourism has no effect on the conditioning of the white sharks, and that all baits have a similar effectiveness for attracting the sharks. However, a different behavioural pattern was observed when fresh bait and chum were used, which could increase the potential of accidents during ecotourism

Prvi dokumentirani zapis o Tetragonurus cuvieri Risso, 1810. (Perciformes, Stromatoidea) duž kalabrijskih obala (Južna Italija, Središnji Mediteran)

The first record of Tetragonurus cuvieri Risso, 1810 off Calabrian coast (Southern Italy, Central Mediterranean) is reported. The specimen, a male of 361 mm total length, was found at a depth of 7 m during a scientific visual census research activity, in March 2017. The sighting was located off the Tyrrhenian coast of Calabria (Paola: 39.355453N, 16.029192E). The present finding represents the 1st documented record for the Tyrrhenian coast of the Calabria region.Objavljen je prvi podatak o Tetragonurus cuvieri Risso, 1810. godine u blizini kalabrijske obale (Južna Italija, Središnji Mediteran). Primjerak mužjaka ukupne dužine 361 mm, pronađen je na dubini od 7 m, u ožujku 2017. godine u blizini Tirenske obale Calabrie (Paola: 39.355453N, 16.029192E). Ovaj nalaz predstavlja prvi dokumentirani zapis za Tirensku obalu pokrajine Calabria