Marine mammals through time: when less is more in studying palaeodiversity

The validity of biological explanations of patterns of palaeodiversity has been called into question owing to an apparent correlation of diversity with the amount of sedimentary rock preserved. However, this claim has largely been based on comprehensive estimates of global marine Phanerozoic diversity, thus raising the question of whether a similar bias applies to the records of smaller, well-defined taxonomic groups. Here, new data on European Caenozoic marine sedimentary rock outcrop area are presented and compared with European occurrences of three groups of marine mammals (cetaceans, pinnipedimorphs and sirenians). Limited evidence was found for a correlation of outcrop area with marine mammal palaeodiversity. In addition, similar patterns were identified in the cetacean and pinnipedimorph diversity data. This may point to the preservation of a genuine biological signal not overwhelmed by geological biases in the marine mammal diversity data, and opens the door to further analyses of both marine mammal evolution and geological bias in other small and well-defined groups of taxa.

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Temporal patterns of barren intervals in the Phanerozoic

Paleobiology ◽

10.1666/07042.1 ◽

2008 ◽

Vol 34 (1) ◽

pp. 155-161 ◽

Cited By ~ 21

Author(s):

Andrew B. Smith ◽

A. J. McGowan

Keyword(s):

Sedimentary Rock ◽

Western Europe ◽

Sedimentary Rocks ◽

Direct Consequence ◽

Rock Outcrop ◽

Shallow Marine ◽

Marine Diversity ◽

Marine Realm ◽

Weak Negative Correlation ◽

Marine Sedimentary Rock

It has recently been argued that barren intervals of marine sedimentary rock are less common in the Cenozoic than in the Paleozoic, and that this arises as a direct consequence of widespread epeiric seas and the prevalence of dysaerobic conditions at such times. We show, using an independent and more direct measure of rock outcrop through time in western Europe, that barren marine sedimentary rocks do become less frequent toward the present, but that this is not linked to any epeiric-seas effect. The proportion of barren to fossiliferous rock outcrop correlates well with the inferred Phanerozoic marine diversity curve (although more so in the Paleozoic than in the post-Paleozoic), and shows no correlation or only a weak negative correlation with area over which the sediments have been deposited. We therefore concluded that the Phanerozoic trend in fossiliferousness most likely records the degree to which space is occupied in the shallow marine realm.

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Cyclicity in the fossil record mirrors rock outcrop area

Biology Letters ◽

10.1098/rsbl.2005.0345 ◽

2005 ◽

Vol 1 (4) ◽

pp. 443-445 ◽

Cited By ~ 40

Author(s):

Andrew B Smith ◽

Alistair J McGowan

Keyword(s):

Recommendations for Sustainable Cetacean-Based Tourism in French Territories: A Review on the Industry and Current Management Actions

Tourism in Marine Environments ◽

10.3727/154427320x15943351217984 ◽

2020 ◽

Vol 15 (3) ◽

pp. 211-235

Author(s):

Josephine Chazot ◽

Ludovic Hoarau ◽

Pamela Carzon ◽

Jeanne Wagner ◽

Stéphanie Sorby ◽

...

Keyword(s):

Marine Mammal ◽

Marine Mammals ◽

French Polynesia ◽

Legal Framework ◽

Whale Watching ◽

Cetacean Species ◽

Commercial Activities ◽

Management Actions ◽

Overseas Territories ◽

Socioeconomic Benefits

Whale-watching activities provide important socioeconomic benefits for local communities and constitute powerful platform incentives for marine mammals' protection or more broadly marine environments. However, these activities can cause adverse effects on targeted populations, with considerable downside associated risks of injuries and fatality for whale watchers during inwater interactions. France with its overseas territories has the second largest exclusive economic zone (EEZ), in which more than half of existing cetacean species are encountered. In these territories, recreational and commercial whale watching, including swim-with cetacean activities, have recently developed. Yet few studies focused on these activities and their associated impacts across French territories, leading to an unclear assessment of the situation. To address this issue, we reviewed cetaceans' occurrence within the French EEZ, whale-watching industry, targeted species, local management of marine mammal-based tourism activities, and regulations in France mainland and some overseas territories (Reunion Island, Mayotte, and French Polynesia). Fortyeight species are encountered in the French EEZ, and 15 are targeted by whale-watching activities. A total of 185 operators, including 34% offering swim-with-cetaceans tours, offered trips in France and overseas in 2019. While several more or less restrictive regulations exist locally, our results indicate that French's national legal framework for marine mammals' protection remains inadequate and insufficient to cope with the recent development of this activity. As conservation biologists, managers, and stakeholders from these French territories, we cooperated to provide general guidelines for a sustainable development of whale watching at a national scale. We urge (1) to legally acknowledge and regulate whale-watching commercial activities; (2) to create a national legal framework regarding whale watching and swim-with marine mammals practices, while accounting for local distinctiveness and disparities across regions; (3) to conduct more research to evaluate local short- and long-term impacts on targeted marine mammal populations as well as the socioeconomic benefits; and (4) to reinforce synergetic relations between the different stakeholders.

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Allometry of diving capacity in air-breathing vertebrates

Canadian Journal of Zoology ◽

10.1139/z97-044 ◽

1997 ◽

Vol 75 (3) ◽

pp. 339-358 ◽

Cited By ~ 182

Author(s):

Jason F. Schreer ◽

Kit M. Kovacs

Keyword(s):

Body Mass ◽

Marine Mammals ◽

Strong Relationship ◽

Allometric Relationship ◽

Air Breathing ◽

Diving Depth ◽

Maximum Duration ◽

Phocid Seals ◽

Bird Group ◽

Taxonomic Groups

Maximum diving depths and durations were examined in relation to body mass for birds, marine mammals, and marine turtles. There were strong allometric relationships between these parameters (log10 transformed) among air-breathing vertebrates (r = 0.71, n = 111 for depth; r = 0.84, n = 121 for duration), although there was considerable scatter around the regression lines. Many of the smaller taxonomic groups also had a strong allometric relationship between diving capacity (maximum depth and duration) and body mass. Notable exceptions were mysticete cetaceans and diving/flying birds, which displayed no relationship between maximum diving depth and body mass, and otariid seals, which showed no relationship between maximum diving depth or duration and body mass. Within the diving/flying bird group, only alcids showed a significant relationship (r = 0.81, n = 9 for depth). The diving capacities of penguins had the highest correlations with body mass (r = 0.81, n = 11 for depth; r = 0.93, n = 9 for duration), followed by those of odontocete cetaceans (r = 0.75, n = 21 for depth; r = 0.84, n = 22 for duration) and phocid seals (r = 0.70, n = 15 for depth; r = 0.59, n = 16 for duration). Mysticete cetaceans showed a strong relationship between maximum duration and body mass (r = 0.84, n = 9). Comparisons across the various groups indicated that alcids, penguins, and phocids are all exceptional divers relative to their masses and that mysticete cetaceans dive to shallower depths and for shorter periods than would be predicted from their size. Differences among groups, as well as the lack of relationships within some groups, could often be explained by factors such as the various ecological feeding niches these groups exploit, or by variations in the methods used to record their behavior.

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Cetacean Research and Citizen Science in Kenya

Frontiers in Marine Science ◽

10.3389/fmars.2021.642399 ◽

2021 ◽

Vol 8 ◽

Author(s):

Michael Gilbert Mwango’mbe ◽

Jane Spilsbury ◽

Steve Trott ◽

Judith Nyunja ◽

Nina Wambiji ◽

...

Keyword(s):

Citizen Science ◽

Marine Mammal ◽

Marine Mammals ◽

Bottlenose Dolphins ◽

Conservation Strategies ◽

Science Data ◽

Pilot Whale ◽

Area Of Interest ◽

Mammal Conservation ◽

Kenyan Coast

In 2011, several non-governmental and government agencies established the Kenya Marine Mammal Network (KMMN) to provide a platform for the consistent collection of data on marine mammals along the Kenyan coast, identify areas of importance and engage marine users and the general public in marine mammal conservation. Prior to the KMMN, relatively little was known about marine mammals in Kenya, limiting conservation strategies. The KMMN collects data nationwide through dedicated surveys, opportunistic sightings and participative citizen science, currently involving more than 100 contributors. This paper reviews data on sightings and strandings for small cetaceans in Kenya collated by the KMMN. From 2011 to 2019, 792 records of 11 species of small cetaceans were documented. The most frequently reported inshore species were the Indo-Pacific bottlenose dolphin and Indian Ocean humpback dolphin. Offshore species, included killer whales, short-finned pilot whale and long-snouted spinner dolphin. Indo-Pacific bottlenose dolphins, long-snouted spinner dolphins, striped dolphins and Risso’s dolphins were recorded through stranding reports. The efforts of the KMMN were disseminated through international meetings (International Whaling Commission, World Marine Mammal Conference), national status reports, outreach and social media. Data has also supported the identification of three IUCN Important Marine Mammal Areas and one Area of Interest in Kenya. Further research is needed to improve estimates of cetacean abundance and distribution, particularly in unstudied coastal areas, and to assess the extent of anthropogenic threats associated with fisheries, coastal and port development, seismic exercises and unregulated tourism. The expansion of the network should benefit from the participation of remote coastal fishing communities, government research agencies, tourism and seismic operations, among others. The KMMN demonstrated the value of dedicated and citizen science data to enhance marine mammal conservation strategies to boost awareness and eco-tourism and to bring the public and science closer together, promoting research and effective conservation efforts.

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Resurgence of an apex marine predator and the decline in prey body size

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1910930116 ◽

2019 ◽

Vol 116 (52) ◽

pp. 26682-26689 ◽

Cited By ~ 8

Author(s):

Jan Ohlberger ◽

Daniel E. Schindler ◽

Eric J. Ward ◽

Timothy E. Walsworth ◽

Timothy E. Essington

Keyword(s):

Life History ◽

Body Size ◽

Chinook Salmon ◽

Marine Mammal ◽

Marine Mammals ◽

Size Structure ◽

Economic Value ◽

Killer Whales ◽

Selective Predation ◽

Marine Predator

In light of recent recoveries of marine mammal populations worldwide and heightened concern about their impacts on marine food webs and global fisheries, it has become increasingly important to understand the potential impacts of large marine mammal predators on prey populations and their life-history traits. In coastal waters of the northeast Pacific Ocean, marine mammals have increased in abundance over the past 40 to 50 y, including fish-eating killer whales that feed primarily on Chinook salmon. Chinook salmon, a species of high cultural and economic value, have exhibited marked declines in average size and age throughout most of their North American range. This raises the question of whether size-selective predation by marine mammals is generating these trends in life-history characteristics. Here we show that increased predation since the 1970s, but not fishery selection alone, can explain the changes in age and size structure observed for Chinook salmon populations along the west coast of North America. Simulations suggest that the decline in mean size results from the selective removal of large fish and an evolutionary shift toward faster growth and earlier maturation caused by selection. Our conclusion that intensifying predation by fish-eating killer whales contributes to the continuing decline in Chinook salmon body size points to conflicting management and conservation objectives for these two iconic species.

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Marine Mammal Evolution

Encyclopedia of Marine Mammals ◽

10.1016/b978-0-12-373553-9.00160-7 ◽

2009 ◽

pp. 692 ◽

Cited By ~ 1

Author(s):

J.G.M. Thewissen ◽

Bobbi Jo Schneider

Keyword(s):

Marine Mammal ◽

Mammal Evolution

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The impacts of climate change on marine mammals: early signs of significant problems

Oryx ◽

10.1017/s0030605307001524 ◽

2007 ◽

Vol 41 (1) ◽

pp. 19-26 ◽

Cited By ~ 113

Author(s):

Mark P. Simmonds ◽

Stephen J. Isaac

Keyword(s):

Climate Change ◽

Marine Mammal ◽

Marine Mammals ◽

Delphinapterus Leucas ◽

Polar Regions ◽

Baleen Whale ◽

Direct Observations ◽

Management Plans ◽

Conservation Plans ◽

Impacts Of Climate Change

Climate change is now known to be affecting the oceans. It is widely anticipated that impacts on marine mammals will be mediated primarily via changes in prey distribution and abundance and that the more mobile (or otherwise adaptable) species may be able to respond to this to some extent. However, the extent of this adaptability is largely unknown. Meanwhile, within the last few years direct observations have been made of several marine mammal populations that illustrate reactions to climate change. These observations indicate that certain species and populations may be especially vulnerable, including those with a limited habitat range, such as the vaquita Phocoena sinus, or those for which sea ice provides an important part of their habitat, such as narwhals Monodon monoceros, bowhead Balaena mysticetus and beluga Delphinapterus leucas whales and polar bears Ursus maritimus. Similarly, there are concerns about those species that migrate to feeding grounds in polar regions because of rapidly changing conditions there, and this includes many baleen whale populations. This review highlights the need to take projected impacts into account in future conservation and management plans, including species assessments. How this should be done in an adequately precautionary manner offers a significant challenge to those involved in such processes, although it is possible to identify at this time at least some species and populations that may be regarded as especially vulnerable. Marine ecosystems modellers and marine mammal experts will need to work together to make such assessments and conservation plans as robust as possible.

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Marine mammals and Japanese long-line fishing vessels in Australian waters: operational interactions and sightings

Pacific Conservation Biology ◽

10.1071/pc060031 ◽

2006 ◽

Vol 12 (1) ◽

pp. 31 ◽

Cited By ~ 4

Author(s):

Catherine Bell ◽

Peter Shaughnessy ◽

Margie Morrice ◽

Bob Stanley

Keyword(s):

Marine Mammal ◽

Marine Mammals ◽

East Coast ◽

Fishing Gear ◽

Killer Whales ◽

Fishing Vessels ◽

Long Line ◽

Target Fish ◽

Pilot Whales ◽

Warm Temperate

Observers from the Australian Fisheries Management Authority worked on randomly chosen Japanese long-line vessels in the Australian Fishing Zone (AFZ) between 1980 and 1997. Observer reports (n = 451) were inspected for interactions or sightings of marine mammals. An operational interaction was defined as an activity or behaviour that involved direct contact between a marine mammal and fishing gear, bait, target fish or bycatch, or indications that the marine mammal was feeding. A sighting was defined as the recording of marine mammals that passed the vessel without changing course and/or did not appear to interact with the vessel or its gear. Observers witnessed 23 interactions and made another 44 sightings of marine mammals. A further 24 interactions and sightings were relayed by crew members. Killer whales were reported most frequently: most incidences of fish being damaged, taken or frightened away were attributed to them. Eleven marine mammals were caught: two died, seven were released, and the fate of two others was not recorded. Between 1991 and 1996, when observer coverage was 11.5% overall in the AFZ, the incidence of interactions was 1.71 per million hooks set. The estimated number of interactions in that seven-year period was 157 in the AFZ. Since 1997, the long-line fishery has been conducted by Australian vessels, primarily off the east coast of mainland Australia in warm-temperate waters. A higher proportion of interactions can be expected with killer whales and short-finned pilot whales in these waters, and fewer with seals.

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Marine mammals' influence on ecosystem processes affecting fisheries in the Barents Sea is trivial

Biology Letters ◽

10.1098/rsbl.2008.0628 ◽

2009 ◽

Vol 5 (2) ◽

pp. 204-206 ◽

Cited By ~ 4

Author(s):

Peter J Corkeron

Keyword(s):

Marine Mammal ◽

Marine Mammals ◽

Gadus Morhua ◽

Fishery Management ◽

Barents Sea ◽

Scientific Evidence ◽

Primary Component ◽

Clupea Harengus ◽

Balaenoptera Acutorostrata ◽

The Barents Sea

Some interpretations of ecosystem-based fishery management include culling marine mammals as an integral component. The current Norwegian policy on marine mammal management is one example. Scientific support for this policy includes the Scenario Barents Sea (SBS) models. These modelled interactions between cod, Gadus morhua , herring, Clupea harengus , capelin, Mallotus villosus and northern minke whales, Balaenoptera acutorostrata . Adding harp seals Phoca groenlandica into this top-down modelling approach resulted in unrealistic model outputs. Another set of models of the Barents Sea fish–fisheries system focused on interactions within and between the three fish populations, fisheries and climate. These model key processes of the system successfully. Continuing calls to support the SBS models despite their failure suggest a belief that marine mammal predation must be a problem for fisheries. The best available scientific evidence provides no justification for marine mammal culls as a primary component of an ecosystem-based approach to managing the fisheries of the Barents Sea.

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