Assessing the current status of Hexanchus griseus in the Mediterranean Sea using local ecological knowledge

Nuez, Ignasi; Giovos, Ioannis; Tiralongo, Francesco; Penadés-Suay, Jaime; Ćetković, Ilija; Lorenzo, Manfredi Di; Kleitou, Periklis; Bakiu, Rigers; Bradaï, Mohamed Nejmeddine; AL-Mabruk, Sara A. A.; Roxani, Naasan Aga - Spyridopoulou,; Sabbio, Andréa; Gazo, Manel

doi:10.1016/j.marpol.2022.105378

Cited by 10 publications

(6 citation statements)

References 59 publications

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“…A complementary solution could be the active engagement of fishermen to endorse improved fishing practices (Ellis et al, 2017), and the use of devices able to reduce the by-catch (Brcǐćet al, 2015;Nuez et al, 2023). Currently, experimental trials the use by-catch reduction devices are showing remarkable positive effects, with a significant decrease of the incidental captures of deep-water elasmobranchs without negative effects on commercial yields (see the results of the LIFE ELIFE project).…”

Section: Possible Management and Conservation Measuresmentioning

confidence: 99%

Jaws from the deep: biological and ecological insights on the kitefin shark Dalatias licha from the Mediterranean Sea

Bottaro,

Sinopoli,

Bertocci

et al. 2023

Front. Mar. Sci.

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Due to their late maturation, extreme longevity, low fecundity and slow growth rates, deep-sea Chondrichthyes are extremely vulnerable to human impacts. Moreover, assessing the impact of deep-sea fisheries is difficult, as many species (including sharks) are part of the bycatch and are often discarded at sea, and/or landed under generic commercial-species codes. The lack of this information on fishery data sets and the limited availability of species-specific life history data make challenging the management of deep-sea Chondrichthyes. The kitefin shark Dalatias licha is a cosmopolitan elasmobranch, mainly found on continental and insular shelf-breaks and slopes in warm-temperate and tropical waters. This species is a common by-catch of the deep-sea trawling, considered as “Endangered” by the IUCN Red List for all European waters, Mediterranean Sea included. Here we present the results of a study based on a total of 78 specimens of kitefin shark collected over 3 years in the Ligurian Sea (NW Mediterranean) as by-catch from deep-water fisheries. Total length ranged from 380 to 1164 mm, and individual weight ranged from 198 to 8000 g. Immature and mature individuals showed a sex ratio dominated by males. Adult males were observed throughout the year, while mature females were observed only in spring-summer. These data lead to hypothesise a spatial segregation between genders. The kitefin shark diet was dominated by bony fish (mainly Macrouridae) and other small sharks (e.g., Galeus melastomus and Etmopterus spinax), but their gut included plastic items and parasites. Data reported here underline the rarity, complex ecology and the threat for this shark species and support the urgency of promoting initiatives for their monitoring and conservation.

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Section: Possible Management and Conservation Measuresmentioning

confidence: 99%

Jaws from the deep: biological and ecological insights on the kitefin shark Dalatias licha from the Mediterranean Sea

Bottaro,

Sinopoli,

Bertocci

et al. 2023

Front. Mar. Sci.

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“…The 80 m-depth camera, located in areas with a deep drop-off has, for the first time, allowed the observation of deep-sea species. An example is the bluntnose sixgill shark (Hexanchus griseus), which is abundant in the Mediterranean by direct observation of bycatch by the trawl fleet in the area [21], but still very difficult to study and observe in situ. The challenge is now to obtain more in situ images and contribute to a better knowledge of these and other rare species, such as the seven-gill shark (Heptranchias perlo) [38] in the Balearic Island waters.…”

Section: Discussionmentioning

confidence: 99%

“…It is a highly invasive sampling technique as it involves species being injured or killed directly when caught or released. Stock depletion, overfishing, and by-catch have decimated elasmobranch populations in the Mediterranean [17][18][19], with most species caught as valuable bycatch in trawl and net multispecies fisheries [20][21][22]. Oceanic pelagic sharks are threatened by surface longlining targeting species, such as swordfish and tuna [23,24], worsening the situation of pelagic sharks, such as white sharks (Carcharodon carcharias) and blue sharks (Prionace glauca) [19].…”

Section: Introductionmentioning

confidence: 99%

Improved Baited Remote Underwater Video (BRUV) for 24 h Real-Time Monitoring of Pelagic and Demersal Marine Species from the Epipelagic Zone

Prat-Varela¹,

Torres²,

Cervantes³

et al. 2023

JMSE

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Bait-based remote underwater video (BRUV) systems are effective devices for remotely observing fish and other marine organisms in challenging environments. The development of a long duration (24 h) surface BRUV observation surveys allowed the monitoring of scarce and elusive pelagic sharks and the direct impact on non-targeted species of longline fishing in the Western Mediterranean. Technological limitations, such as the limited storage capacity and a single surface camera, were improved by (i) adding a deep camera equipped with light (below 80 m depth) and (ii) replacing Gopros with a multi-camera video surveillance system (surface and depth) with a storage capacity of several days and access to real-time observation. Based on a deployment effort of 1884 h video data, we identified 11 blue sharks (Prionace glauca) and one bluntnose sixgill shark (Hexanchus griseus), a deep-sea species that scarcely swims at the surface. The real-time observation capability was a powerful tool for reducing logistical costs and for raising environmental awareness in educational and outreach programmes.

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“…The MEDLEM database stores information about bycatch incidents, sightings and strandings of large elasmobranchs across the Mediterranean Sea (Mancusi et al, 2020). Moreover, a small number of recently published species-specific records (e.g., Nuez et al, 2023) from this area were also included in order to accurately analyze species frequency in the various catches. The 37 records reported in Ćetković et al (2022a) were extracted from the Montenegrin DCRF reports to the General Fisheries Commission for the Mediterranean (GFCM).…”

Section: Dataset and Data Sourcesmentioning

confidence: 99%

Prvi popis hrskavičnjača Crne Gore temeljen na kombinaciji monitoringa gospodarskog ribolova i građanske znanosti

Ćetković,

Serena,

Barash

et al. 2024

Acta Adriat. (Online)

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Chondrichthyans are considered a highly threatened marine species, due both to the intense fishing pressure they have experienced in the world’s Oceans over several decades, and other threats, such as habitat loss, climate change and marine pollution. A rapid decline in their populations could trigger significant negative changes in marine ecosystems, highlighting the need for improved conservation measures. This study analyzes the current state of this group in the waters of Montenegro (in the southeastern Adriatic Sea). The first national checklist is provided here, comprising of 44 species, with information on their occurrence frequencies in Montenegrin fishery catches. The dataset used consists of 1469 records obtained from 281 field samplings conducted as part of the official monitoring of commercial fisheries (DCF-DCRF) aswell as 1222 records derived from citizen science. The latter contributed significantly in documenting a greater number of species, particularly those considered threatened or rare in the region, and/or overlooked by DCF-DCRF monitoring. The frequency of species in Montenegrin catches is described based on the percentage of their records in the total number of records originating from local fisheries. The obtained results indicate that only 16% of the species recorded in Montenegro are commonly present in country’s catches, while 66% are either rare or not observed in local fishery. The creation of the country’s first checklist might contribute to overcoming drawbacks in national legislation and protection measures, notably by reporting the presence of endangered species in national marine waters.

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Assessing the current status of Hexanchus griseus in the Mediterranean Sea using local ecological knowledge

Cited by 10 publications

References 59 publications

Jaws from the deep: biological and ecological insights on the kitefin shark Dalatias licha from the Mediterranean Sea

Jaws from the deep: biological and ecological insights on the kitefin shark Dalatias licha from the Mediterranean Sea

Improved Baited Remote Underwater Video (BRUV) for 24 h Real-Time Monitoring of Pelagic and Demersal Marine Species from the Epipelagic Zone

Prvi popis hrskavičnjača Crne Gore temeljen na kombinaciji monitoringa gospodarskog ribolova i građanske znanosti

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