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

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.

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.

Blood Respiratory Properties and the Effect of Swimming on Blood Gas Transport in the Leopard Shark Triakis Semifasciata

1990 ◽  
Vol 151 (1) ◽  
pp. 161-173 ◽  
Author(s):  
N. CHIN LAI ◽  
IEFFREY B. GRAHAM ◽  
LOUIS BURNETT
Keyword(s):  
Gas Transport ◽  
Lactate Concentration ◽  
Respiratory Acidosis ◽  
Significant Decline ◽  
Blood Gas ◽  
Blood Ph ◽  
Leopard Shark ◽  
The Mean ◽  
Triakis Semifasciata

Changes in vascular pressures, blood respiratory properties and blood gas transport induced by swimming were investigated in the leopard shark Triakis semifasciata (Girard). In resting sharks, the mean ventral and dorsal aortic pressures (systolic/diastolic) were 6.8/5.6 kPa and 4.5/3.9 kPa, respectively, and only the former were increased significantly during swimming. Swimming also caused a significant decline in venous Po2 (1.6 to 0.9kPa), O2 content (0.9 to 0.4mmoill−1) and percentage O2 saturation {SO2, 39 to 18%) but the arterial variables were not affected. A significant decline in venous pH and an increase in venous Po2 also occurred during swimming but lactate concentration did not increase during or after swimming. An in vivo dissociation curve compiled from blood Po2 and So2 data for sharks in the resting, swimming and post-swimming recovery phases shows a mean P50 of 2.04 kPa, as determined by Hill transformation. The pH-bicarbonate plot for this fish shows a weak blood buffer capacity of 9.3mmoll−11pHunit−1 and during swimming the average blood pH and bicarbonateconcentration follow the buffer line which was not compensated in recovery. Neither oxygenated nor deoxygenated blood pH values were affected by CO2 equilibration, suggesting the absence of a Haldane effect. Thus, at the expense of respiratory acidosis, Triakis can aerobically sustain long (up to 60min) and moderately intense (0.45 Ls−1, where L is body length) periods of swimming by increasing cardiac output and tapping its venous reserve. Introduction Most vertebrate circulatory

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