Shark Research Papers - Academia.edu (original) (raw)

Forty years after the release of Steven Spielberg's Jaws the image of the shark in popular culture and public memory still bears the influence of that film. This article explores: recent high-profile human/ shark interactions, the impact... more

Forty years after the release of Steven Spielberg's Jaws the image of the shark in popular culture and public memory still bears the influence of that film. This article explores: recent high-profile human/ shark interactions, the impact of the Stewart Island shark cage diving industry, the body of traditional beliefs and lore about sharks exists along the southern coast of New Zealand, and the way that Jaws has influenced modern perceptions of sharks. The theoretical perspective of multispecies ethnography is suggested as a possible vehicle for further unpacking our understanding of human/ shark interactions.

Hiu karet (Prionace glauca) adalah hiu pelagis yang menjadi target tangkapan nelayan artisanal Tanjung Luar dan umumnya tertangkap di Samudera Hindia Selatan Nusa Tenggara. Penelitian ini bertujuan untuk mengetahui sebaran ukuran dan... more

Hiu karet (Prionace glauca) adalah hiu pelagis yang menjadi target tangkapan nelayan artisanal Tanjung Luar dan umumnya tertangkap di Samudera Hindia Selatan Nusa Tenggara. Penelitian ini bertujuan untuk mengetahui sebaran ukuran dan beberapa parameter populasi hiu karet (Prionace glauca) yang tertangkap di perairan selatan Nusa Tenggara. Analisis dilakukan terhadap 1.414 ekor hiu karet yang tertangkap rawai hanyut di selatan Nusa Tenggara dan didaratkan di Tanjung Luar, Lombok Timur selama periode 2014 – 2016. Analisis data dilakukan secara deskriptif dan beberapa parameter populasi diduga menurut rumus empiris Froese & Binohlan (2000). Hasil penelitian menunjukkan sebaran ukuran panjang total hiu karet berkisar antara 95 – 383 cm (jantan) dan 113 – 333 cm (betina) dengan rerata ukuran yang tertangkap tidak berbeda nyata. Nisbah kelamin didominasi oleh hiu karet jantan dan telah matang kelamin. Dugaan terhadap beberapa parameter adalah: nilai L∞ antara 333,02 - 385,59 cm dengan Lm jantan antara 187,21 – 215 cm dan betina 139,82 – 159,34 cm. Sebanyak 39,96 – 44,71% hiu karet tertangkap pada panjang optimumnya sehingga ada kecenderungan tangkap lebih.

Amid declining shark populations because of overfishing, a burgeoning shark watching industry, already well established in some locations, generates benefits from shark protection. We compile reported economic benefits at shark watching... more

Amid declining shark populations because of overfishing, a burgeoning shark watching industry, already well established in some locations, generates benefits from
shark protection. We compile reported economic benefits
at shark watching locations and use a meta-analytical
approach to estimate benefits at sites without available data. Results suggest that, globally, c. 590,000 shark watchers expend >USD 314 million per year, directly supporting 10,000 jobs. By comparison, the landed value of global shark fisheries is currently c. USD 630 million and has been in decline for most of the past decade. Based on current observed trends, numbers of shark watchers could more than double within the next 20 years, generating >USD 780 million in tourist expenditures around the world. This
supports optimistic projections at new sites, including those
in an increasing number of shark sanctuaries established
primarily for shark conservation and enacted in recognition
of the ecological and economic importance of living sharks.

Shark Bite Incident in Khan Younis Sea, Gaza Strip, State of Palestine. By: Prof. Dr. Sc. Norman Ali Bassam Khalaf-Prinz Sakerfalke von Jaffa. Abstract: Shark Bite Incident in Gaza: The Palestinian Fisherman Khaled Radwan Al-Lahham from... more

In recent years Azorean fishermen reported the presence of the smalltooth sand tiger shark, Odontaspis ferox (Risso, 1810), a very rare demersal shark species, associated with insular shelves and slopes, with occasional incursions into... more

In recent years Azorean fishermen reported the presence of the smalltooth sand tiger shark, Odontaspis ferox (Risso, 1810), a very rare demersal shark species, associated with insular shelves and slopes, with occasional incursions into shallow waters and of poorly known biology and ecology. There are fourteen new records of this species, between 1996 and 2014, captured by spearfishing, harpoons, hand lines, or entangled in fishing gear in the Azores. These records were analysed and complemented with fishermen interviews, providing new locations and new biological data for this species. Also, specimens photographs were studied and post-mortem analysis were carefully carried out in one individual. This species is rare and captured only as bycatch in shallow waters. More detailed information on this species is critically needed in order to assess its conservation status and implement management guidelines. Bycatch statistics are crucial in this respect.

Elasmobranch specimens from the construction site of Mizunami-Kita Junior High School in Mizunami City are described. These specimens consists of five genera; four sharks of Nebrius, Carcharhinus, Galeocerdo, and Megasqualus, and one ray... more

Elasmobranch specimens from the construction site of Mizunami-Kita Junior High School in Mizunami City are described. These specimens consists of five genera; four sharks of Nebrius, Carcharhinus, Galeocerdo, and Megasqualus, and one ray of Rhinoptera. Megasqualus occidentalis (Agassiz, 1856), a new combination is proposed here.

A new fossil record of shark tooth in Gunma Prefecture was found from an outcrop in the Gunma Safari Park, Tomioka City, Gunma Prefecture. The specimen (GSP-00001) is derived from the late Early Miocene Obata Formation, Tomioka Group. The... more

A new fossil record of shark tooth in Gunma Prefecture was found from an outcrop in the Gunma Safari Park, Tomioka City, Gunma Prefecture. The specimen (GSP-00001) is derived from the late Early Miocene Obata Formation, Tomioka Group. The specimen is only the coronal part of the crown, though the apex is lost. The crown is large and robust. Its shape is almost triangular. The preserved cutting edge is all serrated. The mesial and distal edge show slightly expansion to outside in lingual (or labial) view. And the labial surface of the crown is slightly curved opposite to lingual side. Distal profile slightly shows sigmoid curve in labial view. These characteristics of the specimen and comparison with the natural tooth set of C. megalodon from Saitama (Kawamoto specimen) suggest that the specimen found at the Gunma Safari Park is a lower third or fourth tooth of fossil megatooth shark, Carcharodon megalodon. This specimen is recognized as the first specimen of the species from the Oba...

A study of human impact on the presence and behavior of sharks was carried out June to November 2008 at these Red Sea diving sites: Elphinstone Reef, Daedalus Reef, Big Brother Is., Small Brother Is., Zabargad Is., Rocky Is., and Habili... more

A study of human impact on the presence and behavior of sharks was carried out June to November 2008
at these Red Sea diving sites: Elphinstone Reef, Daedalus Reef, Big Brother Is., Small Brother Is., Zabargad Is., Rocky
Is., and Habili Ali. A total of 194 hours of field observations was done; sharks were encountered during 110 of 138
dives. Eight species of sharks for a total of 292 specimens were recorded: whale shark Rhincodon typus (1 specimen),
pelagic thresher shark Alopias
pelagicus
(12), silvertip shark Carcharhinus albimarginatus (1), grey reef
shark Carcharhinus amblyrhynchos (61), silky shark Carcharhinus falciformis (2), oceanic whitetip shark Carcharhinus
longimanus
(123), whitetip reef shark Triaenodon obesus (5), scalloped hammerhead Sphyrna lewini (87).
The frequency of encounters in Elphinstone Reef is considerably lower than in the other study areas. Presence of
recreational divers was recorded during almost all the dives: 134 cases on the total of 138 dives, with a presence of
a total of 971 boats and 15,601 divers. Both the mean number of divers and the mean number of boats recorded for
each dive are higher for Elphinstone Reef than in the other study sites. In Elphinstone Reef the high number of boats
is also widely distributed for the entire area, making it impossible for the sharks to avoid human presence. The
massive human presence in Elphinstone Reef is negatively affecting the presence of sharks and may also increase
the probability of attacks on humans occurring. The number and conduct of boats of divers and boats frequenting
this site need to be regulated by appropriate rules. It is therefore urgently necessary for Elphinstone Reef to be
declared a protected area.

A new record of fossil shark tooth in Gunma Prefecture was found from the collection of the Iwajuku Museum, Midori City, Gunma Prefecture. The specimen (Iwajuku Museum 2005-A326) was collected by natural historian, Shosaku IWASAWA, from... more

A new record of fossil shark tooth in Gunma Prefecture was found from the collection of the Iwajuku Museum, Midori City, Gunma Prefecture. The specimen (Iwajuku Museum 2005-A326) was collected by natural historian, Shosaku IWASAWA, from the Late Miocene Mamioka Tuff, Tenjinyama, Midori City (former Kasakake Village), Gunma Prefecture, central Japan. The specimen has a relatively large and high triangular shaped crown. The cutting edge is smooth and almost straight in distal profile. Mesial profile slightly shows sigmoid curve in labial view. The labial face of the crown is almost flat, though the apex pointed to labial direction. The root is bulky and stout. These characteristics indicate that the tooth is identified to upper right intermediate tooth of fossil 'mako' shark (" Isurus " hastalis). This specimen is recognized as the first vertebrate fossil of the geological unit. Futhermore, another fossil specimen of shark tooth that Shosaku IWASAWA collected is desc...

A research has been done to determine some biological aspects of Western Longnose Spurdog (Squalus edmundsi) from the Eastern Indian Ocean Fishing Region in Indonesia (WPP 573). A total of 1797 samples were recorded from bottom longline... more

A research has been done to determine some biological aspects of Western Longnose Spurdog (Squalus edmundsi) from the Eastern Indian Ocean Fishing Region in Indonesia (WPP 573). A total of 1797 samples were recorded from bottom longline fisheries at Tanjung Luar, Lombok from July 2015 to November 2016 by a trained enumerator. The study revealed that Selat Alas and the south west of Sumbawa waters are the most fished areas in the region for this species, with the peak fishing season may occur from January to March. The average catch rate of S. edmundsi was about 8 individuals per boat. The size of sharks varied from 470 mm to 1150 m total length (TL), with average size was 723.6±111.5 mm. Size distributions and sex ratio between females and males were significantly different, indicating a sexual dimorphism. This study revealed a fact that there was no seasonal pattern in the reproductive cycle of S. edmundsi in this region, which means the parturition may occur throughout the year. Analysis on its population status showed that this species was very susceptible to overfishing. This condition should be responded by the government through management actions for its fishery.

The oldest fossil of Echinorhinus in the northwestern Pacific area is described in this paper. The fossil, Echinorhinus sp. （GMNH-PV-3227） , was found in a cobble-size rock block which is estimated that a part of a calcareous nodule of... more

The oldest fossil of Echinorhinus in the northwestern Pacific area is described in this paper. The fossil, Echinorhinus sp. （GMNH-PV-3227） , was found in a cobble-size rock block which is estimated that a part of a calcareous nodule of the Turonian Saku Formation, Yezo Group. The age of the hitherto known oldest fossil Echinorhinus in the northwestern Pacific area was recorded from the Santonian of Japan. However, the GMNH-PV-3227 specimen was accompanied by the specimen of ammonite, Romaniceras (Romaniceras) sp. The range of the subgenus of this ammonite is limited to the middle to upper Turonian. Thus, GMNH-PV-3227 marks the oldest record of this genus in the northwestern Pacific area.

Tanjung Luar merupakan sentra penangkapan hiu di Indonesia karena jumlah tangkapan hiu yang didaratkan jauh lebih banyak dari semua tempat penangkapan hiu di Indonesia. Penelitian ini bertujuan untuk mengetahui hasil tangkapan dan... more

Tanjung Luar merupakan sentra penangkapan hiu di Indonesia karena jumlah tangkapan hiu yang didaratkan jauh lebih banyak dari semua tempat penangkapan hiu di Indonesia. Penelitian ini bertujuan untuk mengetahui hasil tangkapan dan kelimpahan relatif beberapa jenis hiu yang didaratkan di Tanjung Luar, Lombok. Data diperoleh melalui wawancara dan catatan enumerator di Tanjung Luar, Lombok Timur pada bulan Januari – November 2015. Analisis data dilakukan secara deskriptif dan disajikan sebagai persentase kelimpahan relatif. Hasil menunjukkan bahwa tangkapan hiu pada tahun 2015 berfluktuasi setiap bulannya dengan puncak hasil tangkapan terjadi pada bulan September 2015. Total tangkapan hiu sebesar 237,5 ton dengan rerata tangkapan sebesar 1,4 ton/hari. Komposisi tangkapan terdiri atas 28 spesies yang terbagi dalam sebelas famili. Carcharhinus falciformis (42,06%), Prionace glauca (10,45%), dan Carcharhinus limbatus (10,31%) secara berurutan merupakan hiu predominan dengan kelimpahan relatif lebih besar dari 10%.

Sexual segregation in the lesser spotted dogfish (Scyliorhinus canicula) is most likely driven by the female strategy of avoidance of the males, which causes the formation of female groups in the nooks and shelters on the seafloor. This... more

Sexual segregation in the lesser spotted dogfish (Scyliorhinus canicula) is most likely driven by the female strategy of avoidance
of the males, which causes the formation of female groups in the nooks and shelters on the seafloor. This strategy allows them
to reduce the multiple events of male sexual advances, which are energetically expensive. In order to examine the existence of
a social structure in female lesser spotted dogfish aggregations and the impact of the presence of males on them, we analyzed
the structure of the social network and the temporal stability of the associations of two populations each one including five
females. An easy insertion of the males in female population was made possible by the presence of a homogeneous initial
social structure with quite weak bonds. The social structure is regulated by differences in the individual behaviour, resulting
in different strength and stability of aggregations of conspecifics.
The addition of the males produced a reduction of the Average Association Index and of the measures related to the populations’
network, strength of the associations and level of indirect connections of the individual. The presence of the males seems to
have a greater effect on the individuals that are more weakly linked; while key individuals typically reduce their network
values, but remain well integrated in the population; peripheral individuals have more variables values. This result indicates
that relations exist between the sex, which is in contrast with the hypothesis of the female avoidance of males, which should
produce strong and stable female groups. The actual knowledge of the behaviour and distribution of the Mediterranean lesser
spotted dogfish does not prove the existence of a sexual segregation in this species. Based on the results we can assume that
the home-ranges of females and males are not separated and that the male presence does not trigger a female aggregation
mechanism. It is noteworthy that males have a destructive effect on the female associations, as these ones have shown a
reduction of all the values. This might suggest that, in nature, the male presence and therefore the potential male sexual
coercion may cause the spatial dispersion of the individuals of the population and reduce the cohesion of the group.

Heavy metals are regarded as conservative pollutants due to their non-biodegradable nature. This group of pollutant is released directly into the coastal water through various industrial effluents, antifouling paints, agricultural wastes... more

Heavy metals are regarded as conservative pollutants due to their non-biodegradable nature. This group of pollutant is released directly into the coastal water through various industrial effluents, antifouling paints, agricultural wastes etc. The heavy metals thus discharged accumulate gradually within the body tissues of organisms. The present paper is a snapshot of the concentrations of Zn, Cu, Pb and Cd in the shark species Glyphis gangeticus collected from four different sampling stations of lower Gangetic delta.

For free-swimming marine species like sharks, only population genetics and demographic history analyses can be used to assess population health/status since baseline population numbers are usually unknown. We investigated the population... more

For free-swimming marine species like sharks, only population genetics and demographic history analyses can be used to assess population health/status since baseline population numbers are usually unknown. We investigated the population genetics of blacktip reef sharks, Carcharhinus melanopterus; one of the most abundant reef-associated sharks and the apex predator of many shallow water reefs of the Indian and Pacific Oceans. Our sampling includes 4 widely separated locations in the Indo-Pacific and 11 islands in French Polynesia with different levels of coastal development. 14 microsatellite loci were analysed for samples from all locations and 2 mitochondrial DNA fragments, the control region and cytochrome b, were examined for 10 locations. For microsatellites, genetic diversity is higher for the locations in the large open systems of the Red Sea and Australia than for the fragmented habitat of the smaller islands of French Polynesia. Strong significant structure was found for distant locations with FST values as high as ~0.3, and a smaller but still significant structure is found within French Polynesia. Both mitochondrial genes show only a few mutations across the sequences with a dominant shared haplotype in French Polynesia and New Caledonia suggesting a common lineage different to that of East Australia. Demographic history analyses indicate population expansions in the Red Sea and Australia that may coincide with sea level changes after climatic events. Expansions and flat signals are indicated for French Polynesia as well as a significant recent bottleneck for Moorea, the most human-impacted lagoon of the locations in French Polynesia.

To properly manage world fisheries, especially highly migratory species, there are numerous treaties that have been implemented by specialized international fishery commissions. One of the oldest organizations is the International... more

To properly manage world fisheries, especially highly migratory species, there are numerous treaties that have been implemented by specialized international fishery commissions. One of the oldest organizations is the International Commission for the Conservation of Atlantic Tunas (ICCAT). The main focus of this review was to summarize the history, roles and responsibilities of ICCAT, and to evaluate ICCAT’s management of sharks in general and specifically for shortfin mako (Isurus oxyrinchus) shark. This review found that the Convention was established 40 years ago, but it was not until 2004 that the commission conducted its first population assessment on pelagic sharks.

Proposed benefits of multiple paternity include increased reproductive output, elevated fitness of progeny, and maintenance of population genetic diversity. However, an alternative consideration is whether multiple paternity is simply an... more

Proposed benefits of multiple paternity include increased reproductive output, elevated fitness of progeny, and maintenance of population genetic diversity. However, an alternative consideration is whether multiple paternity is simply an unavoidable byproduct of sexual conflict, with males seeking to maximize mating encounters while females seek to minimize the stress of copulation. Here we examine the polyandrous mating system in sharks, with a focus on the reproductive genetics of the shortspine spurdog, Squalus mitsukurii. Members of the genus Squalus are long-lived, slow-growing, and employ the longest gestation period of any vertebrate. To evaluate multiple paternity and genetic diversity in S. mitsukurii, we genotyped 27 litters plus 96 individuals with eight microsatellite loci. Further, 670 bp of the mtDNA control region were sequenced in 112 individuals to examine population structure. Squalus mitsukurii in Hawaii show low genetic diversity relative to other sharks (π = 0.0010 ± 0.0008) and no significant population structure in the Hawaiian Archipelago. Direct allele counts and Bayesian approximations returned concordant estimates of 11% multiple paternity, the lowest observed in sharks to date. Pearson correlation analysis of multiple paternity and heterozygosity in five shark studies reveals an R2 = 0.40. Though non-significant, these data indicate that multiple paternity may promote retention of genetic diversity. Considering the protracted reproductive interval of S. mituskurii, sexual conflict that results from conflicting male and female reproductive strategies may favor the development of female mating avoidance behavior to minimize trauma. In S. mitsukurii this behavior includes segregation of sexes and an asynchronous reproductive cycle.