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David W Sims - One of the best experts on this subject based on the ideXlab platform.
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sieving a living a review of the biology ecology and conservation status of the plankton feeding Basking Shark cetorhinus maximus
Advances in Marine Biology, 2008Co-Authors: David W SimsAbstract:The Basking Shark Cetorhinus maximus is the world's second largest fish reaching lengths up to 12 m and weighing up to 4 tonnes. It inhabits warm-temperate to boreal waters circumglobally and has been the subject of fisheries exploitation for at least 200 years. There is current concern over its population levels as a consequence of directed harpoon and net fisheries that in the north-east Atlantic Ocean alone took over 100,000 mature individuals between 1946 and 1997. As a consequence, it is not known whether populations are recovering or are at a fraction of their historical, pre-fishing biomass. They are currently Red-listed as vulnerable globally, and endangered in the north-east Atlantic. The Basking Shark is one of only three Shark species that filter seawater for planktonic prey and this strategy dominates key aspects of its life history. Until recently, very little was known about the biology, ecology and behaviour of this elusive species. The advent of satellite-linked electronic tags for tracking has resulted in considerable progress in furthering our understanding of Basking Shark behaviour, foraging, activity patterns, horizontal and vertical movements, migrations and broader scale distributions. Genetic studies are also beginning to reveal important insights into aspects of their global population structure, behaviour and evolutionary history. This chapter reviews the taxonomy, distribution and habitat, bionomics and life history, behaviour, population structure, exploitation, management and conservation status of the Basking Shark. In doing so, it reveals that whilst important behavioural and ecological information has been gained, there are still considerable gaps in knowledge. In particular, these relate to the need to resolve population sizes, spatial dynamics such as population sub-structuring and sexual segregation, the critical habitats occupied by pregnant females, and the distribution and scale of fishery by-catch rates. Although challenging, it is arguable that without achieving these goals the conservation status of the Basking Shark will be difficult to assess accurately.
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spatial distribution patterns of Basking Sharks on the european shelf preliminary comparison of satellite tag geolocation survey and public sightings data
Journal of the Marine Biological Association of the United Kingdom, 2005Co-Authors: Emily J Southall, David W Sims, J D Metcalfe, J I Doyle, S Fanshawe, C Lacey, J Shrimpton, J L Solandt, C SpeedieAbstract:Current concerns about the population levels of the Basking Shark (Cetorhinus maximus) in the north-east Atlantic have prompted a need to understand population distribution, habitat preference and centres of abundance. In this study, spatial distribution maps derived from satellite-tag geolocations, boat surveys and public sightings data were compared. The broad distribution patterns revealed by these diierent methods are similar, but there are considerable diierences in density distributions. Surface sightings data show high densities, or ‘hotspots’ in the Hebridean Sea, Clyde Sea, Irish Sea and close inshore around Devon and Cornwall. Tag geolocations, in contrast, identi¢ed two areas where individuals spent considerable time outside the distributions indicated by surveys and public sightings: the Celtic Sea and Western Approaches of the English Channel. The reason for this disparity and its implications for population estimates for the species are discussed.
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habitat specific normal and reverse diel vertical migration in the plankton feeding Basking Shark
Journal of Animal Ecology, 2005Co-Authors: David W Sims, Emily J Southall, Geraint A Tarling, J D MetcalfeAbstract:Summary 1. Megaplanktivores such as filter-feeding Sharks and baleen whales are at the apex of a short food chain (phytoplankton‐zooplankton‐vertebrate) and are sensitive indicators of sea-surface plankton availability. Even though they spend the majority of their time below the surface it is still not known how most of these species utilize vertical habitat and adapt to short-term changes in food availability. 2. A key factor likely to control vertical habitat selection by planktivorous Sharks is the diel vertical migration (DVM) of zooplankton; however, no study has determined whether specific ocean-habitat type influences their behavioural strategy. Based on the first high-resolution dive data collected for a plankton-feeding fish species we show that DVM patterns of the Basking Shark Cetorhinus maximus reflect habitat type and zooplankton behaviour. 3. In deep, well-stratified waters Sharks exhibited normal DVM (dusk ascent‐dawn descent) by tracking migrating sound-scattering layers characterized by Calanus and euphausiids. Sharks occupying shallow, inner-shelf areas near thermal fronts conducted reverse DVM (dusk descent‐dawn ascent) possibly due to zooplankton predator‐prey interactions that resulted in reverse DVM of Calanus . 4. These opposite DVM patterns resulted in the probability of daytime-surface sighting differing between these habitats by as much as two orders of magnitude. Ship-borne surveys undertaken at the same time as trackings reflected these behavioural differences. 5. The tendency of Basking Sharks to feed or rest for long periods at the surface has made them vulnerable to harpoon fisheries. Ship-borne and aerial surveys also use surface occurrence to assess distribution and abundance for conservation purposes. Our study indicates that without bias reduction for habitat-specific DVM patterns, current surveys could under- or overestimate Shark abundance by at least 10-fold.
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the effects of climate variability on zooplankton and Basking Shark cetorhinus maximus relative abundance off southwest britain
Fisheries Oceanography, 2005Co-Authors: Peter A Cotton, David W Sims, Sam Fanshawe, Mark ChadwickAbstract:At small spatial scales Basking Sharks (Cetorhinus maximus) forage selectively on zooplankton along thermal fronts, but the factors influencing broader scale patterns in their abundance and distribution remain largely unknown. Using long-term sightings data collected off southwest Britain between 1988 and 2001, we show that the number of Basking Sharks recorded was highly correlated with abiotic factors, principally sea surface temperature (SST) and the lagged effect of SST in the previous month, but only very weakly to zooplankton density. This suggests that the changes in number of Basking Sharks recorded over large spatio-temporal scales are more closely related to the availability of climatedriven thermal resources than prey availability, whereas the converse is supported by previous studies at local scales. Taken together, these results imply scale-dependent behavioural responses in Basking Sharks, with small-scale foraging movements linked by broad scale responses to temperature variation.
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congruent trends in long term zooplankton decline in the north east atlantic and Basking Shark cetorhinus maximus fishery catches off west ireland
Fisheries Oceanography, 2002Co-Authors: David W Sims, Philip C ReidAbstract:Trends in Basking Shark (Cetorhinus maximus) fishery catches off Achill Island, west Ireland between 1949 and 1975 were examined in relation to zooplankton (total copepod) abundance in four adjacent sea areas over a 27-year period. The numbers of Basking Sharks caught and copepod abundance showed downward trends and were positively correlated (r-value range, 0.44–0.74). A possible explanation for the downward trend in Shark catches was that progressively fewer Basking Sharks occurred there between 1956 and 1975 because fewer copepods, their food resource, occurred near the surface off west Ireland over the same period. We suggest that the decline in Basking Sharks may have been due to a distributional shift of Sharks to more productive areas, rather than a highly philopatric, localized stock that was over-exploited.
Matthew J Witt - One of the best experts on this subject based on the ideXlab platform.
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Basking Shark sub surface behaviour revealed by animal towed cameras
PLOS ONE, 2021Co-Authors: Jessica L Rudd, Tiago Bartolomeu, Haley R Dolton, Owen M Exeter, Christopher Kerry, Lucy A Hawkes, S M Henderson, Marcus Shirley, Matthew J WittAbstract:While biologging tags have answered a wealth of ecological questions, the drivers and consequences of movement and activity often remain difficult to ascertain, particularly marine vertebrates which are difficult to observe directly. Basking Sharks, the second largest Shark species in the world, aggregate in the summer in key foraging sites but despite advances in biologging technologies, little is known about their breeding ecology and sub-surface behaviour. Advances in camera technologies holds potential for filling in these knowledge gaps by providing environmental context and validating behaviours recorded with conventional telemetry. Six Basking Sharks were tagged at their feeding site in the Sea of Hebrides, Scotland, with towed cameras combined with time-depth recorders and satellite telemetry. Cameras recorded a cumulative 123 hours of video data over an average 64-hour deployment and confirmed the position of the Sharks within the water column. Feeding events only occurred within a metre depth and made up ¾ of the time spent swimming near the surface. Sharks maintained similar tail beat frequencies regardless of whether feeding, swimming near the surface or the seabed, where they spent surprisingly up to 88% of daylight hours. This study reported the first complete breaching event and the first sub-surface putative courtship display, with nose-to-tail chasing, parallel swimming as well as the first observation of grouping behaviour near the seabed. Social groups of Sharks are thought to be very short term and sporadic, and may play a role in finding breeding partners, particularly in solitary Sharks which may use aggregations as an opportunity to breed. In situ observation of Basking Sharks at their seasonal aggregation site through animal borne cameras revealed unprecedented insight into the social and environmental context of Basking Shark behaviour which were previously limited to surface observations.
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assessing the importance of isle of man waters for the Basking Shark cetorhinus maximus
Endangered Species Research, 2020Co-Authors: Haley R Dolton, Lucy A Hawkes, Jackie Hall, Fiona R Gell, Graham L Hall, Matthew J WittAbstract:This is the final version. Available on open access from Inter Research via the DOI in this record
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Basking Shark breaching behaviour observations west of shetland
Marine Biodiversity Records, 2018Co-Authors: Emma Hayes, Brendan J Godley, Maja Nimakwood, Matthew J WittAbstract:This study reports observations of Basking Sharks (Cetorhinus maximus) sighted during an offshore geophysical survey conducted in July and August 2013, west of Shetland, UK. During the 38-day survey, trained and dedicated marine wildlife observers recorded 19 sightings of Basking Sharks (n = 22 individuals). Of these observations, 17 were of single Sharks, with one observation of two Sharks and one observation of three Sharks. All surface sightings occurred in water depths between 129 and 199 m, predominantly prior to noon local time (79%), and were mostly of Sharks 6–8 m in length, although a young (2 m) individual was also recorded. Breaching behaviour was observed on 21 occasions, by individuals or in small groups. Breaching has been proposed as a male-male competitive behaviour during courtship displays and female Basking Sharks may breach to signal their readiness for mating. Aggregations of Basking Sharks at frontal systems are well documented and linked to the occurrence of prey patches; however, these oceanographic features may also be of importance to courtship. The high number of sightings of Sharks recorded during a relatively short time frame in addition to breaching behaviour and presence of young individuals, suggest that this area west of Shetland may be an important habitat for the Basking Shark.
Alen Soldo - One of the best experts on this subject based on the ideXlab platform.
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Basking Shark cetorhinus maximus occurrence in relation to zooplankton abundance in the eastern adriatic sea
Cybium, 2008Co-Authors: Alen Soldo, Davor Lucic, Ivan JardasAbstract:Le requin pelerin est une espece plutot rare, mais constamment presente en mer Adriatique orientale. Au cours de la periode 2000-2002 son occurrence dans ce secteur a fortement augmente. Sur la base de cette presomption, cet article etudie les relations entre l'abondance de zooplancton et les occurrences du requin pelerin.Il s'avere que la presence accrue de ce requin n'est pas directement influencee par des changements de la temperature et de la salinite. Cependant, les donnees obtenues suggerent un lien entre la densite des copepodes, particulierement de Calanus helgolandicus, et les occurrences de requins pelerins.
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on the presence of Basking Shark cetorhinus maximus in the mediterranean sea
Cybium, 2005Co-Authors: Cecilia Mancusi, Fabrizio Serena, Simona Clo, Marco Affronte, Mohamed Nejmeddline Bradai, Farid Hemida, Alen Soldo, M VacchiAbstract:A B S T R A C T. - The presence of Basking Shark C e t o rhinus maximus Gunnerus, 1765 throughout the Mediterranean Sea was investigated using data stored in the “Large Elasmobranch Monitoring” programme database (Italy), with new records coming from the French area and also including the fi rst data from the eastern sector of the Mediterranean basin. More than 500 records of information on Basking Sharks were included in the database, with older records coming from the 19 th century, but also including the most recent literature. Data revealed the presence of specimens of quite dif ferent sizes that ranged from very young (about 2 m TL) to large adults (8-9 m TL) encompassing large part of the body length range known for this Shark at global scale. Most of the occurrences of the species in Mediterranean are reported off the coastal areas of the western central sectors of the Mediterranean basin, where it is often caught incidentally by trammel nets in spring. T h e numerous records registered in the last two decades may be related rather to an increasing scientific and public interest on the species than to an actual abundance trend of the Mediterranean population. The knowledge on the distribution and population structure of Basking Shark in the Mediterranean basin plays an important role in the implementation of conservation measures of such protected species.
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occurrence of great white Shark carcharodon carcharias linnaeus 1758 and Basking Shark cetorhinus maximus gunnerus 1165 in the eastern adriatic and their protection
Periodicum Biologorum, 2002Co-Authors: Alen Soldo, Ivan JardasAbstract:Within 29 different species of Sharks reported in the Adriatic, the great white Shark and the Basking Shark are included as very rare species. These two species, like other Sharks, have life history characteristics, such as slow growth, delayed ages at maturity, low fecundity and long gestation periods, that make them particularly vulnerable to overfishing. A number of studies, carried out throughout the world indicate that numbers of these two species decline. This paper gives collected data of records of these two species in the Eastern Adriatic, based on bibliographical research and collaboration with numerous persons and institutions. Since 19th century 61 records of the great white Shark and 27 records of the Basking Shark have been collected in the Eastern Adriatic. According to obtained results a proposal of their protection in the same area has been presented.
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new record and some morphological data of the Basking Shark cetorhinus maximus gunnerus 1765 in the eastern adriatic
Annales : anali za istrske in mediteranske študije. Series historia naturalis, 1999Co-Authors: Alen Soldo, Melita Peharda, Vlado Onofri, Niksa Glavic, Pero TutmanAbstract:On March 23rd 1999 Basking Shark, Cetorhinus maximus (Gunnerus, 1765), was caught in gillnet and found by fishermen near Osobljava harbour at Peljesac penninsula. The paper gives some morphological and meristic data and general information about specie and its occurrence in the Adriatic.
Geoff J Taylor - One of the best experts on this subject based on the ideXlab platform.
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ram filter feeding and nocturnal feeding of whale Sharks rhincodon typus at ningaloo reef western australia
Fisheries Research, 2007Co-Authors: Geoff J TaylorAbstract:The paper reports feeding behaviours of whale Sharks (Rhincodon typus) at Ningaloo Reef, Western Australia that have been observed during field trips over a period of 23 years. Two distinct feeding behaviours have been observed, namely passive feeding, which resembles the ram filter-feeding of the Basking Shark (Cetorhinus maximus), and active feeding at the surface, as previously described in the literature. Nocturnal surface feeding behaviour is reported. The targeted prey species were specific to the different feeding techniques and times. Contrary to previous reports, the gills of the Shark moved actively in a rhythmical fashion during both of the observed feeding modes. The principal prey species identified at Ningaloo have been the euphausiid Pseudeuphausia latifrons, portuniid megalopa, stomatopod larvae, copepods, chaetognatha, and schools of small fish. The diurnal appearance of whale Sharks at the surface and the passive feeding witnessed during daylight hours, suggests that the whale Shark is searching for localised aggregations of plankton that persist at the surface in the weeks following the reef spawning.
Bruce J Welton - One of the best experts on this subject based on the ideXlab platform.
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cetorhinus cf c maximus gunnerus lamniformes cetorhinidae a Basking Shark from the late miocene empire formation coos bay oregon
Bulletin Southern California Academy of Sciences, 2013Co-Authors: Bruce J WeltonAbstract:Abstract The family Cetorhinidae Gill includes one extant genus, Cetorhinus Blainville, and a single living species, the Basking Shark, C. maximus (Gunnerus). Basking Sharks are coastal pelagic to oceanic with circumglobal distribution in boreal to warm-temperate waters of the continental and insular shelves. Second only in size to the whale Shark, Rhincodon typus, Basking Sharks attain a maximum total length of 12 to 15 m (although generally not exceeding 9.8 m), and are planktivorous, feeding by filtering copepods, barnacles, decapod larvae and fish eggs from the water. The first Tertiary records of undisputed cetorhinids are from the middle Eocene of Antarctica, possibly the middle Eocene of Russia, and the late Eocene of Oregon. Eocene cetorhinids are referred to Keasius taylori, and Oligocene through early Miocene Basking Sharks are traditionally assigned to Keasius parvus. The earliest occurrence of Cetorhinus in the northeastern Pacific is early Miocene, and fossils attributed to this genus are rel...
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cetorhinus cf c maximus gunnerus lamniformes cetorhinidae a Basking Shark from the late miocene empire formation coos bay oregon
Bulletin Southern California Academy of Sciences, 2013Co-Authors: Bruce J WeltonAbstract:Abstract The family Cetorhinidae Gill includes one extant genus, Cetorhinus Blainville, and a single living species, the Basking Shark, C. maximus (Gunnerus). Basking Sharks are coastal pelagic to oceanic with circumglobal distribution in boreal to warm-temperate waters of the continental and insular shelves. Second only in size to the whale Shark, Rhincodon typus, Basking Sharks attain a maximum total length of 12 to 15 m (although generally not exceeding 9.8 m), and are planktivorous, feeding by filtering copepods, barnacles, decapod larvae and fish eggs from the water. The first Tertiary records of undisputed cetorhinids are from the middle Eocene of Antarctica, possibly the middle Eocene of Russia, and the late Eocene of Oregon. Eocene cetorhinids are referred to Keasius taylori, and Oligocene through early Miocene Basking Sharks are traditionally assigned to Keasius parvus. The earliest occurrence of Cetorhinus in the northeastern Pacific is early Miocene, and fossils attributed to this genus are rel...