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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
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.
Cooke, J.G. 2018. Eschrichtius robustus. The IUCN Red List of Threatened Species 2018:
e.T8097A50353881. Downloaded on 18
April 2021.
Dunham, J. S., & Duffus, D. A. (2002). Diet of gray whales (Eschrichtius robustus) in clayoquot sound, British
columbia, Canada. Marine mammal science, 18(2), 419-437.
Jones, M. L., Swartz, S. L., & Leatherwood, S. (Eds.). (2012). The gray whale: Eschrichtius robustus. Academic Press.
Nelson, T. A., Duffus, D. A., Robertson, C., & Feyrer, L. J. (2008). Spatial-temporal patterns in intra-annual gray whale
foraging: Characterizing interactions between predators and prey in Clayquot Sound, British Columbia, Canada. Marine
mammal science, 24(2), 356-370.
Moore, S. E., Grebmeier, J. M., & Davies, J. R. (2003). Gray whale distribution relative to forage habitat in the northern
Bering Sea: current conditions and retrospective summary. Canadian Journal of Zoology, 81(4), 734-742.
Perryman, W. L., Donahue, M. A., Perkins, P. C., & Reilly, S. B. (2002). Gray whale calf production 19942000: are
observed fluctuations related to changes in seasonal ice cover?. Marine Mammal Science, 18(1), 121-144.
Perrin, W.F. (2021). World Cetacea Database. Eschrichtius robustus (Lilljeborg, 1861). Accessed through: World
Register of Marine Species at: on 2021-04-18
Rice, D. W., Wolman, A. A., & Braham, H. W. (1984). The gray whale, Eschrichtius robustus. Marine Fisheries
Review, 46(4), 7-14.
Scheinin, A. P., Kerem, D., MacLeod, C. D., Gazo, M., Chicote, C. A., & Castellote, M. (2011). Gray whale
(Eschrichtius robustus) in the Mediterranean Sea: anomalous event or early sign of climate-driven distribution change?.
Marine Biodiversity Records, 4.
ResearchGate has not been able to resolve any citations for this publication.
Full-text available
On 8 May 2010, a gray whale was sighted off the Israeli Mediterranean shore and twenty-two days later, the same individual was sighted in Spanish Mediterranean waters. Since gray whales were last recorded in the North Atlantic in the 1700s, these sightings prompted much speculation about this whale's population origin. Here, we consider three hypotheses for the origin of this individual: (1) it represents a vagrant individual from the larger extant population of gray whales found in the eastern North Pacific; (2) it represents a vagrant individual from the smaller extant population found in the western North Pacific; or (3) it represents an individual from the previously thought extinct North Atlantic population. We believe that the first is the most likely, based on current population sizes, on known summer distributions, on the extent of cetacean monitoring in the North Atlantic and on the results of a performed route analysis. While it is difficult to draw conclusions from such singular events, the occurrence of this individual in the Mediterranean coincides with a shrinking of Arctic Sea ice due to climate change and suggests that climate change may allow gray whales to re-colonize the North Atlantic as ice and temperature barriers to mixing between northern North Atlantic and North Pacific biomes are reduced. Such mixing, if it were to become widespread, would have implications for many aspects of the marine conservation and ecology of these two regions.
Full-text available
In Clayquot Sound, British Columbia, gray whales (Eschrichtius robustus) forage primarily on mysids (Family Mysideae) and also on crab larvae (Family Porcellanidae) that are constrained to specific habitat, which relate to bathymetric depths. In this paper we characterize the interactions of gray whales and their prey by analyzing fine scale spatial-temporal patterns in foraging gray whale distribution within a season. Kernel density estimators are applied to two seasons (1998 and 2002) of high- resolution data on foraging by gray whales. By partitioning data from each foraging season into several time periods (12 in 1998 and 11 in 2002), using a temporal autocorrelation function, and generating kernel density estimated surfaces for each time period, it is possible to identify discrete areas of increasing and declining foraging effort. Our results indicate that gray whales forage on mysids throughout a season and opportunistically forage on crab larvae. The episodic crab larvae feeding may reduce, but not eliminate, pressure to mysid populations enabling mysids to reassemble swarms and continue to support gray whale foraging in the latter part of the season. Results suggest that when managing marine environments, gray whale populations require multiple and connected habitats for summer foraging.
The gray whale (. Eschrichtius robustus) is the only living species in the family Eschrichtiidae. It is a slow-moving sturdy mysticete, slimmer than right whales and stockier than most rorquals. It attains a maximum length of 15.3 m (50 ft) and its skin is mottled light to dark gray with whitish blotches and heavily infested with barnacles and cyamids, or " whale lice, " especially on the head. Instead of a dorsal fin, the back has a hump followed by a series of fleshy knobs, or " knuckles" along the tailstock. The behavioral ecology of the gray whale is unique among mysticetes, as it is the most coastal; makes the longest migration; calves in warm bays, lagoons, and coastal areas; and is an intermittent suction feeder that regularly forages on benthos, apart from feeding opportunistically on plankton and nekton by gulping and skimming. Once found throughout the Northern Hemisphere, the gray whale became extinct in the Atlantic and now is a relict species confined to the productive neritic and estuarine waters of the North Pacific Ocean and adjacent waters of the Arctic Ocean. The eastern population (also called the American , California , or Chukchi stock) occurs in the eastern North Pacific and Amerasian Arctic Oceans, whereas the remnant western population (also called the Asian , Korean , or Okhotsk stock ) occurs in the western North Pacific (off Asia). The western gray whale is now a remnant population close to extinction that occurs off Russia, Japan, Korea, and China and is one of the most critically endangered populations of whales.
Hundreds of gray whales (Eschrichtius robustus) stranded dead along beaches from Mexico to Alaska in 1999 and 2000. The cause of the mortalities remains unknown, but starvation resulting from a reduction in prey, especially in the Chirikov Basin, was suggested as the cause. In the 1980s, the Chirikov Basin was considered a prime gray whale feeding area, but there has been no recent comprehensive assessment of whale or prey distribution and abundance. In 2002, a 5-day survey for gray whales revealed restricted distribution in the basin and a 3- to 17-fold decline in sighting rates. To put these data in context, a retrospective summary of gray whale and benthic fauna distribution and abundance was undertaken. During the 1980s, gray whale sighting rates in the Chirikov Basin were highly variable. Ampeliscid amphipods dominated the benthos where gray whale sighting rates were highest. Available measures of biomass suggest a downturn in amphipod productivity from 1983 to 2000, when estimates of gray whale population size were increasing, suggesting that the whales simply expanded their foraging range. We encourage long-term study of the Chirikov Basin as a location where predator–prey responses to changing ocean climate can be researched, because decadal time series data are available.
We conducted shore-based sighting surveys to estimate the number of northbound migrating gray whale calves passing Piedras Blancas, California, for seven consecutive years (1994-2000). In addition, we conducted aerial surveys to determine offshore distribution of the migration in 1994 and 1995, measured dayinight migration rates with thermal sensors in 1994-1996, and maintained concurrent replicate watches near the peak of each migration to estimate the proportion of the cowicalf pairs missed by the standard watch team. During good weather, we counted 325, 194, 407, 501, 440, 141, and 96 calves during 1994-2000, respectively. Correcting these counts for periods not on watch and for calves missed, produced final estimates of 945 calves (SE = 68.21) for 1994, 619 calves (SE = 67.19) for 1995, 1,146 calves (SE = 70.67) for 1996, 1,431 calves (SE = 82.02) for 1997, 1,388 calves (SE = 91.84) for 1998, 427 calves (SE = 41.10) for 1999, and 279 calves (SE = 34.79) for 2000. Calf production indices (calf estimateitotal population esti- mate) are 4.2%, 2.7%, 4.896, 5.8%, 5.5%, 1.7%, and 1.1% for the years 1994-2000, respectively. Fluctuations in calf production over this time period were positively correlated with the length of time that primary feeding hab- itat was free of seasonal ice during the previous year.
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. 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: on 2021-04-18