scholarly journals Multiple paternity in leopard shark (Triakis semifasciata) litters sampled from a predominantly female aggregation in La Jolla, California, USA

2013 ◽  
Vol 446 ◽  
pp. 110-114 ◽  
Author(s):  
Andrew P. Nosal ◽  
Eric A. Lewallen ◽  
Ronald S. Burton
Keyword(s):  
Multiple Paternity ◽  
Leopard Shark ◽  
Predominantly Female ◽  
La Jolla ◽  
Triakis Semifasciata

Demography of the central california population of the Leopard Shark (Triakis semifasciata)

1992 ◽  
Vol 43 (1) ◽  
pp. 183 ◽  
Author(s):  
GM Cailliet
Keyword(s):  
Population Growth ◽  
Reproductive Rate ◽  
Shark Species ◽  
Sandbar Shark ◽  
Lemon Shark ◽  
Carcharhinus Plumbeus ◽  
Net Reproductive Rate ◽  
Leopard Shark ◽  
Triakis Semifasciata ◽  
Leopard Sharks

Demographic analyses can be quite useful for effectively managing elasmobranch fisheries. However, they require valid estimates of age-specific mortality and natality rates, in addition to information on the distribution, abundance, habits and reproduction of the population, to produce reliable estimates of population growth. Because such detailed ecological information is usually unavailable, complete demographic analyses have been completed for only four shark species: the spiny dogfish, Squalus acanthias; the soupfin shark, Galeorhinus australis; the lemon shark, Negaprion brevirostris; and most recently the sandbar shark, Carcharhinus plumbeus. In California, reliable estimates of age, growth, mortality, age at maturity, and fecundity are available only for the leopard shark, Triakis semifasciata. A demographic analysis of this species yielded a net reproductive rate (Ro) of 4.467, a generation time (G) of 22.35 years, and an estimate of the instantaneous population growth coefficient (r) of 0.067. If the mean fishing pressure over 10 years (F= 0.084) is included in the survivorship function, Ro and r are reduced considerably, especially if leopard sharks first enter the fishery at early ages. A size limit of 120 cm TL (estimated age 13 years), especially for female sharks, is tentatively proposed for the leopard shark fishery.

Cardiac function of the leopard shark, Triakis semifasciata

1990 ◽  
Vol 160 (3) ◽  
pp. 259-268 ◽  
Author(s):  
N. Chin Lai ◽  
Ralph Shabetai ◽  
Jeffrey B. Graham ◽  
Brian D. Hoit ◽  
Katharina S. Sunnerhagen ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Leopard Shark ◽  
Triakis Semifasciata

scholarly journals Epidermal Microbiomes of Triakis Semifasciata Are Consistent Across Captive and Wild Environments

2021 ◽  
Author(s):  
Asha Goodman ◽  
Bhavya Papudeshi ◽  
Michael P. Doane ◽  
Colton Johnson ◽  
Maria Mora ◽  
...  
Keyword(s):  
Taxonomic Composition ◽  
Shark Species ◽  
Wild Populations ◽  
Microbiome Composition ◽  
Α Diversity ◽  
Novel Association ◽  
Species Specific ◽  
La Jolla ◽  
Triakis Semifasciata ◽  
Leopard Sharks

Abstract Background: Characterizations of sharks-microbe systems in wild environments have outlined patterns of species-specific microbiomes; however, whether captivity affects these trends has yet to be determined. We used high-throughput shotgun sequencing to assess the epidermal microbiome belonging to leopard sharks (Triakis semifasciata) in captive (Birch Aquarium, La Jolla California), semi-captive (<1 year in captivity; Scripps Institute of Oceanography, California) and wild environments (Moss Landing and La Jolla, California). Results: Here we report captive environments do not drive microbiome composition of T. semifasciata to significantly diverge from wild counterparts as life-long captive sharks maintain a species-specific epidermal microbiome resembling those associated with semi-captive and wild populations. Major taxonomic composition shifts observed were inverse changes of top taxonomic contributors across captive duration, specifically an increase of Pseudoalteromonadaceae and consequent decrease of Pseudomonadaceae relative abundance as T. semifasciata increased duration in captive conditions. Moreover, we show captivity did not lead to significant losses in microbial α-diversity of shark epidermal communities. Finally, we present a novel association between T. semifasciata and the Muricauda genus as MAGs revealed a consistent relationship across captive, semi-captive, and wild populations. Conclusions: Our report illustrates the importance of conservation programs for coastal fishes as epidermally-associated microbes of near-shore shark species do not suffer detrimental impacts from long or short-term captivity. Our findings also expand on current understanding of shark epidermal microbiomes, explore the effects of ecologically different scenarios on benthic shark microbe associations, and highlight novel microbial associations that are consistent across captive gradients.

Aspects of Shark Swimming Performance Determined Using a Large Water Tunnel

1990 ◽  
Vol 151 (1) ◽  
pp. 175-192 ◽  
Author(s):  
JEFFREY B. GRAHAM ◽  
HEIDI DEWAR ◽  
N. C. LAI ◽  
WILLIAM R. LOWELL ◽  
STEVE M. ARCE
Keyword(s):  
Body Size ◽  
Swimming Speed ◽  
Swimming Performance ◽  
Beat Frequency ◽  
Swimming Velocity ◽  
Water Tunnel ◽  
Lemon Shark ◽  
Negaprion Brevirostris ◽  
Leopard Shark ◽  
Triakis Semifasciata

A large, sea-going water tunnel was used in various studies of shark swimming performance. The critical swimming velocity (Ucrit, an index of aerobically sustainable swimming speed) of a 70 cm long lemon shark (Negaprion brevirostris Poey) was determined to be 1.1 Ls−1, where L is body length. The Ucrit of the leopard shark (Triakis semifasciata Girard) was found to vary inversely with body size; from about 1.6Ls−1in 30–50cm sharks to 0.6LS−1 in 120cm sharks. Large Triakis adopt ram gill ventilation at swimming speeds between 27 and 60cms−1, which is similar to the speed at which this transition occurs in teleosts. Analyses of tail-beat frequency (TBF) in relation to velocity and body size show that smaller Triakis have a higher TBF and can swim at higher relative speeds. TBF, however, approaches a maximal value at speeds approaching Ucrit, suggesting that red muscle contraction velocity may limit sustained swimming speed. The TBF of both Triakis and Negaprion rises at a faster rate with swimming velocity than does that of the more thunniform mako shark (Isurus oxyrinchus Rafinesque). This is consistent with the expectation that, at comparable relative speeds, sharks adapted for efficient swimming should have a lower TBF. The rates of O2 consumption of swimming lemon and mako sharks are among the highest yet measured for elasmobranchs and are comparable to those of cruise-adapted teleosts.

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