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Bioenergetics and swimming efficiency of juvenile scalloped hammerhead sharks, Sphyrna lewini, in Kaneohe Bay, Oahu, HawaiiLowe, Christopher G 08 1900 (has links)
The goal of this study was to determine the energetic
requirements of juvenile scalloped hammerhead sharks (Sphyrna
lewini) in Kaneohe Bay, Oahu, Hawaii using a multidisciplinary
approach. A large flume/respirometer (635 1)
was constructed to determine the critical swimming speeds
(Ucrit )' swimming kinematics (tailbeat frequency, tailbeat
amplitude, and stride length), and oxygen consumption rates
(V02 ) of juvenile sharks over a range of swimming speeds (U).
Swimming kinematics were also compared with unconstrained
sharks in a seawater pond. These experiments indicated that
tailbeat frequency (TBF) and water temperature could be used
as a predictor of U and V02 for free-swimming sharks in the
field; however, the flume affected the sharks' swimming
kinematics at slow speeds. The flume and pond kinematic
comparisons were used to correct for flume effects on sharks'
V02.
An acoustic tailbeat-sensing transmitter was designed
and constructed to quantify activity and energy consumption
of free-swimming hammerhead shark pups in Kaneohe Bay.
Sharks with transmitters behaved similarly to uninstrumented
sharks, but incurred a 28% increase in cost of transport due
to increased drag from the transmitters. These data were
used to correct for the effects of the transmitter on freeswimming
sharks in the field. Sharks tracked in Kaneohe Bay with tailbeat transmitters
exhibited increased U during dawn and dusk, while sharks
tracked in the warmer summer months had higher activity rates
and metabolic rates (MR) than a shark tracked during the
winter. Sharks tracked in this study had higher MR than
those measured for other species of tropical sharks and, as a
result, require higher daily rations. Low and negative
growth rates determined from sharks in the Bay and declining
catch rates over the season suggest that a large percentage
of the pups in Kaneohe Bay may starve as the result of their
high metabolic requirements. Although prey do not appear to
be li~itingi lack of foraging experience compounded by a high
daily metabolic demand may explain why sharks lose weight
during summer months. Those pups that survive the winter
experience lower MR due to seasonal temperature decline and
less competition as the result of high neonatal mortality. / x, 130 leaves, bound : ill. (some col.) ; 29 cm. / Missing page 74.
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Food-associated conditioning in the smoothhound shark Mustelus mustelus (Linnaeus, 1758)Louw, Erika 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Smoothhound sharks Mustelus mustelus (Chondrichthyes: Triakidae) were
conditioned to associate a compound auditory and electrical conditioned stimulus (CS)
using the presentation of food as the unconditioned stimulus (US). This was done to
investigate the general conditioning process of sharks, specifically the use of conditioned
stimuli, the time frame required for conditioning, the retention of conditioned responses
and the individual learning capabilities of sharks in classical conditioning experiments.
Conditioning was done in two CS experiment replicates, in which the CS and the US
were paired to elicit a conditioned response (CR: entering of a feeding area). Shark
behaviour in these replicates was compared with those of sharks in a CS control. In the
CS control, the CS and US were not paired; consequently no CS-US association was
formed. In contrast, half of the sharks in the 1st and 2nd CS replicates formed the
conditioned CS-US association after five and six days of conditioning training,
respectively. This conditioned association was also retained over a two-month rest
period. However the rate of conditioning of sharks varied, which was thought to be due
to differences in motivational drives, particularly hunger. These experiments
demonstrated that classical conditioning could provide a mechanism whereby
smooth hound sharks can adapt to utilise new food sources.
However these experiments could not demonstrate whether auditory or electrical
cues are more biological relevant signallers of the presence of food for smooth hound
sharks. According to the "belonging ness" phenomenon, for conditioning to be
successful, the CS should be biologically relevant to the US. Therefore by comparisons
of the conditioning success with different conditioned stimuli, the biological relevance of each CS can be determined. To determine the biological relevance of each component
of the compound CS, an auditory or electrical CS was paired with the presentation of
food (US), in separate experiments. The conditioned CS-US association formed in the
majority of the sharks after 60 and 57 conditioning trials in the auditory CS and electrical
CS experiment, respectively. This suggests that both auditory and electrical cues are
biologically relevant signallers of food, facilitating the oppurtunistic feeding behaviour of
smoothhound sharks. However, after five days of conditioning, conditioning with the
electrical CS had proceeded further and the electrical CS-US association was stronger
than the auditory CS-US association. This indicates that electrical cues are more
biologically relevant due to past feeding experiences. Thus, classical conditioning during
past feeding experiences can influence the feeding behaviour of smooth hound sharks. / AFRIKAANSE OPSOMMING: Gladde-hondhaaie Muste/us muste/us (Chondrichthyes: Triakidae) is gekonditioneer
om "n gekombineerde klank en elektriese konditionerings stimulus (CS) met voedsel, die
ongekonditioneerde stimulus (US) te assosieer. Dit is gedoen om die konditionerings
proses, spesifiek die gebruik van konditionerings stimuli, tyd benodig vir konditionering,
behoud van die gekonditioneerde gedrag en individuele leer-vermoëens van haaie in
klassieke konditionerings eksperimente te ondersoek. Konditionering is gedoen in twee
CS eksperiment replikate, waarin die CS en die US saam aangebied is, om "n
konditionerings reaksie (CR: om in 'n voedings area in te beweeg) teweeg te bring. Die
gedrag van haaie in die CS replikate is vergelyk met die van haaie in "n CS kontrole. In
die CS kontrole is die CS en die US nie saam aangebied nie en gevolglik is geen
gekonditioneerde CS-US assosiasie gevorm nie. Daarenteen is die CS-US assosiasie
by die helfte van die haaie in die 1st en 2de CS replikate gevorm, na vyf en ses dae,
onderskeidelik. Hierdie gekonditioneerde CS-US assosiasie het selfs behoue gebly na 'n
twee maande rus periode. Die tempo van konditionering het egter verskil, moontlik
a. g. v. motiverings verskille, veral hongerte. Hierdie eksperimente het gedemonstreer
dat klassieke konditionering kan dien as 'n meganisme waarmee gladde-hondhaaie kan
aanpas om nuwe voedsel bronne te benut.
Hierdie eksperimente kon egter nie demonstreer óf klank stimuli óf elektriese stimuli
meer biologiese relevante seine van die teenwoordighied van voesel is vir gladdehondhaaie
nie. Volgens die "belonging ness" verskynsel, moet die CS biologies relevant
to die US wees, vir konditionering om suksesvol te wees. Dus kan die biologiese relevansie van verskillende konditionerings stimuli bepaal word deur die konditionerings
sukses van elke CS te vegelyk. Om die meer biologiese relevante komponent van die
gekombineerde CS te bepaal, is 'n klank of elektriese CS saam met voedsel aangebied
in aparte eksperimente. Die gekonditioneerse CS-US assosiasie is gevorm by die
meeste van die haaie na 60 en 57 konditionerings proeflopies in die klank en elektriese
CS eksperimente, onderskeidelik. Hierdie resultate dui daarop dat beide klank en
elektriese stimuli biologies relevante siene van voedsel is, wat die oppurtunistiese
voedings wyse van gladde-hondhaaie fasiliteer. Konditionering met die elektriese CS het
egter verder gevorder en die elektriese CS-US assosiasie was sterker as die klank CSUS
assosiasie na vyf dae van konditionering. Dus, mag elektriese stimuli meer biologies
relevant wees weens vorige voedings ervaringe. Dit illustreer dat klasseke konditionering
tydens vorige voedings ervaringe die voedings gedrag van gladde-hondhaaie kan
beinvloed.
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Behavioral responses of juvenile sandbar sharks, Carcharhinus plumbeus, to direct current and alternating current stimuliFitzgerald, Timothy P. 12 January 2012 (has links)
Heading on microfiche: Fitzgerald, Timothy Patrick.
Thesis (M.S.)--University of Hawaii at Manoa, 2002.
Includes bibliographical references (leaves 45-50).
Also available on microfiche.
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Diet and Reproductive Biology of the Blacknose Shark (Carcharhinus Acronotus) from the Southwestern Atlantic OceanFord, Ryan Michael 01 January 2012 (has links)
The blacknose shark (Carcharhinus acronotus) is a common small coastal shark species found in nearshore waters along the southeast coast of the United States, from North Carolina into the Gulf of Mexico and extending further south into the Bahamas. There has been some debate in recent years over the reproductive periodicity of C. acronotus in waters off the U.S. coast. Earlier studies have suggested that Gulf C. acronotus reproduce on an annual basis whereas the Atlantic populations of this species may reproduce biennially. Additionally, there have been no known studies on the diet of C. acronotus. The goal of the present study was to re-evaluate the reproductive biology of the Atlantic populations of C. acronotus with the intent on clarifying discrepancies in reproduction as well as provide information on dietary trends. This was accomplished by examining male and female reproductive tracts and gut contents in animals caught throughout the Atlantic range of C. acronotus. Based on these data, spermatogenesis occurs between late May to early July with peak sperm production occurring in June and July. In females, follicular development is complete by late June-early July with ovulation occurring shortly afterwards. Mating occurs between mid-June and early July based on the presence of fresh mating scars on females captured during this time. Current data suggests that gestation begins late July with parturition occurring late May to early June the following year. As observed in earlier studies, reproductive periodicity appears to be largely biennial. However, evidence for concurrent follicular development and pregnancy was observed in several females, suggesting that at least a portion of the Atlantic population may reproduce on an annual basis. Dietary data shows a dominance of teleost prey items in the diets of C. acronotus with scianids making up the majority of the identifiable teleosts.
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