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Abstract

We continuously hear about upheavals in ecosystems, about a changing sea whose regime shifts we struggle to keep up with. The close encounter with a gray whale in Tyrrhenian waters a few days ago is perhaps a very tangible confirmation of this. It is the third documentation in Mediterranean waters for this species, the last one occurred in 2010 off the Israeli Mediterranean shore and in Spain. This short note is a result of a joint effort made with the help of a citizen scientist who timely documented the unusual event.
DOI: 10.6084/m9.figshare.14445624
SCIENTIFIC NOTE
Upside down sea- a grey host in the Central Tyrrhenian Sea
Gaglioti M.
The grey whale Eschrichtius robustus (Lilljeborg, 1861) belongs to the suborder of Odontocetes, is
a very rare marine mammal in the middle latitudes (Jones et al., 2012; Perrin W.F. 2021).
It is currently protected from the main internationally recognized conservation measures such as the
Marine Mammal Protection Act (MMPA), the IUCN Red List where is mentioned as Least
Concerned (Cooke J.G., 2018) and the Appendix I of the Convention on International Trade in
Endangered Species. To date the effective impacts of climate change on baleen whales are almost
unknown, but it is considered one of the largest threats facing high latitude regions where many gray
whales forage. Most notably, the timing and distribution of sea ice coverage is changing dramatically
with altered oceanographic conditions. Any resulting changes in prey distribution could lead to
changes in foraging behavior (Dunham et al., 2002; Moore et al., 2003), nutritional stress, and
diminished reproduction for gray whales (Perryman et al., 2002). Additionally, changing water
temperature and currents could impact the timing of environmental cues important for navigation and
migration (Nelson et al., 2008).
On 14 April 2021 an unusual sighting occurred in the nearby of the Circeo Man and Biosphere
Reserve, exactly in the east coast of Ponza Island (Frontone beach), approximately 20 nautical miles
apart from San Felice Circeo coast. The unique recognized occurrences of this species in the
Mediterranean Sea happened in 2010 off the Israeli Mediterranean shore and then in Spanish
Mediterranean waters and probably both the observations are linked to the same specimen (Scheinin
et al., 2011).
The first observers of the recent Central Tyrrhenian Sea occurrence have been Giuseppe Mazzella
and his son Vincenzo who documented the
encounter and shared the video on a social
network (Fig.1). For four days from the first
reporting, thanks to the collaboration between
institutions and some citizen scientists, the
animal has been tracked throughout its
movement in the southward direction toward the
Gulf of Naples where it has been closely
observed also by the staff of the main Marine
Protected Areas of this portion of the Central
Tyrrhenian Sea, before its departure in the
direction of Procida where then lost his tracks.
At a first glance this episode highlighted the
positive attitude toward the collaboration aimed
at documenting this unusual event. In few hours
from social networks, websites of local
institutions, research institutes and protected
areas the first video reached thousands of
visualizations followed by additional reports.
Besides, some of the observers get also in touch with the animal driven from the instinctive feeling,
even though it is not properly the right approach considering that is a wild animal already stressed
and evidently disoriented. Indeed, considering that this cetacean is a typical of the northern Pacific
coasts and its distribution is usually limited to this high latitude regions, its occurrence in the
Mediterranean Sea beside its occurrence in very shallow waters, is reasonably due to some difficulty
Figure 1 Screenshot from a video documentation shared on
social networks (Image Credits: Vincenzo Mazzella)
DOI: 10.6084/m9.figshare.14445624
or problems. For this reason, as a general rule is essential do not cause disturbance or annoyance in
the attempt to follow or photograph these animals even though the instinct dictated by the emotion
would lead to not respect this code of conduct.
References
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ResearchGate has not been able to resolve any citations for this publication.
Article
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In Clayoquot Sound, British Columbia, gray whales (Eschrichtius robustus) forage for pelagic, hyperbenthic, and benthic invertebrates. Prey types were collected near feeding whales and at sites where no whales were observed to ascertain whales' diets and to describe prey populations and distributions. Characteristics of prey that are examined include species composition, density, biomass, and size. Whales foraged for mysids, Holmesimysis sculpta being the most abundant species collected. Whales foraged near concentrated patches of porcelain crab zoeal larvae, composed primarily of Pachycheles rudis, 21 –294 times the average density and biomass normally collected. Amphipod biomass, composed primarily of Ampelisca agassizi and A. careyi, was 160 ± 150 g/m2 where whales foraged. Larger amphipods, rather than higher density, resulted in higher amphipod biomass between years. Whales foraged where there was a high proportion (61%) of amphipods > 6 mm in length. Whales initially foraged for amphipods along the 20-m depth contour line; amphipod biomass was best developed and least variable at depths between 16 and 20 m.
Eschrichtius robustus. The IUCN Red List of Threatened Species
  • J G Cooke
Cooke, J.G. 2018. Eschrichtius robustus. The IUCN Red List of Threatened Species 2018: e.T8097A50353881. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T8097A50353881.en. Downloaded on 18 April 2021.
World Cetacea Database. Eschrichtius robustus (Lilljeborg, 1861)
  • W F Perrin
Perrin, W.F. (2021). World Cetacea Database. Eschrichtius robustus (Lilljeborg, 1861). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=137112 on 2021-04-18