Topic 4: Shark Physiology 2 (Stress Response) Flashcards
Where is the Atlantic Sharpnose shark commonly found? Habitat?
- Order: Carcharhiniformes
L> Family: Carcharhinidae - warm temperate water
- common down the coast of Maine and the gulf of Mexico…its caught frequently in long line fishing
Where is the sharp nose shark a year round resident?
- off the shout of South Carolina, Florida and the Florida Keys.
What kinds of migration does the sharp nose shark do?
- inshore to offshore migrations
* migrate with the warmer waters up north
What does the sharp nose shark form during migrations?
- large sexually segregated schools
As winter approaches, where do sharp nose sharks go?
L> what about in the spring?
- move off shore into deeper water
L> they return inshore to mate in spring and give birth after 10-11 month gestation period.
What depths are the sharp nose sharks commonly found?
- up to 920 feet (280m) but they mostly remain in waters less than 32 feet (10m) deep.
Sharpnose sharks are common residents of the surf zone, the Atlantic sharp nose however has been found where?
- estuaries and harbours
Although the sharp nose shark is able to tolerate lower salinity levels they do not what?
- venture into fresh water like the bull shark ( Carcharhinus leucas)
- it can tolerate changing conditions
Sharpnose Sharks:
- Males of this species reach maturity between ___ and __ years of age, at which time they average between __-___ inches (__-__cm) total length.
- 2 and 2.4
- 31.5-33.5 inches ( 80-85cm)
Sharpnose Sharks:
- Females of this species reach sexual maturity at total lengths between __-__ inches (__-__cm), after __-__ years. Maximum length of the Atlantic sharp nose shark is __ inches (__cm)
- 33.5-35.5 inches (85-90cm)
- 2.4-2.8 years
- 43.3 inches (110cm)
Sharpnose Sharks:
- maturity level is mostly determined by?
- What sex is largest and why?
- size
- females
L> to help with producing offspring…
Sharpnose Sharks:
- The longer and bigger the female the more what?
- more pups are produced
Sharpnose Sharks:
- whats the longest recorded length of this species?
1.1m
Sharpnose Sharks:
- number of pups vary between - and is related to?
- 4-7 pups
- size of the mother ( typical of shark species)
Sharpnose Sharks:
- viviparous or oviparous ?
- viviparous
L> placental sac.–> nurses offspring
-live young
Sharpnose Sharks:
- how do the females of this species differ from other charcharhinids ?
- ovaries of the female develop on the left!
Sharpnose Sharks:
- At birth, the pups are how long in length? (cm and inches)
- 11.4-14.6 inches (29-37cm)
Sharpnose Sharks:
- On average, pups grow __inches (_cm) a month during the first three months of life.
- 2 inches (5cm)
Sharpnose Sharks:
- After the first three months of life what does the growth rate of pups slow down to?
- it slows to an average of 0.35 inches (0.9cm) a month during the winter and spring months.
Sharpnose Sharks:
- Upon reaching lengths of 24-26 inches (60-65cm) what happens to growth rate in the pups?
L> also at this size what do the sharks begin to form?
- it begins a linear increase of 0.5 inches (1.3 cm) a month for approximately a year.
- they begin to form a distinct size class, which separates them from newborns.
Sharpnose Sharks:
- At 2ft long what are they classified as? Juvenile or newborns?
Juvenile
Sharpnose Sharks:
- They have a pretty rapid growth rate as pups but it slows down in the __ and __ months. What is the bonus of having such a rapid growth rate early on?
- winter and spring
- good to get them out of the bottom of the food chain!
What shark is one of the most common costal shark caught via by catch in shrimp fisheries?
- Sharpnose sharks
Sharpnose Sharks:
- When they are caught what do fisheries utilize them for?
- meat, fins, bait for larger sharks. (especially used when they are pups that are caught!)
Sharpnose Sharks:
- What are they listed as by the IUCN?
L> what does IUCN stand for?
- Least concern because they are very plentiful.
L> International Union for Conservation of Nature
International Union for Conservation of Nature
- what makes them good study subjects for stress response?
- their biology is very well studied!
Majority of previous studies on stress response used ___ sharks because they are easy to handle.
small
Any large sharks that were studied for stress response how did they measure stress?
L> issues ?
- by taking blood samples more than an hour after initial stress.
L> can not measure onset….there may have been in recovery phase or peaked!
In 2001-2 study before the blood sample was taken from the larger sharks how long were they on the line?
- more than an hour
L> they were also in deep ocean..
Why is playing with a caught fish for as long as possible a major concern for recreational fishing?
- if you have ppl coming out and paying for it say… 5-6 ppl sharing a boat to catch a shark land say one rod catches a shark…everyone is expected to get a turn with that shark. So if each person gets a turn for 10mins thats 60 mins total the animal has been stressed out and still fighting …it was never addressed before until the present study looked at in lecture!
What is a massive dilemma for trying to measure stress response initially?
- you cannot because of the pre-catch phase.
L> the present study’s primary goal was to establish this baseline stress response!
What are the objectives of the current study?(2)
- obtain baseline estimates for hematological parameters
2. Describe physiological changes
What is one of the most blatantly obvious stress signs for a shark?
- If a blotchy pattern is present on the stomach. It is a stress response via blood vessels dilating. Normally the bely should be white. This is the very first sign of stress.
- a couple minutes should be the limit at which you examine a specimen not long periods of times.
In the current study explain the methods. (in general)
- Used hook and line but the subjects were kept on the line but allowed to swim freely.
- 5 Blood samples were taken over an hour. The sharks were reeled in slowly and the blood sample was taken every 15 minutes. (0.5ml extracted)
In the present study did they record the time of initial catch?
yes
What is the downside to leaving the shark on the line even if they are able to swim freely?
- the animal is still being stressed out
L> the present study didn’t indicate how much the animal stressed in the process
In the present study on average how long was in between catch and blood sampling of the sharks?
- 3 mins!
L> baseline
Does the blood chemistry vary much from species to species?
YES its all over the place.
- and it depends on how the shark is doing naturally vs being stressed from capture
Are sharks stills stressed out even if they are being reeled in slowly?
YES … therefore you cannot really measure catch and release …just catch and stress
Present study:
- where were blood samples taken from?
- caudal area ( big artery in that area)
Present study:
- what did they examine in the blood sample?
- Whole Blood
- hematorit: packed blood cells in plasma… mostly RBC. - Plasma
- lactic acid
- glucose
- osmolality - overall osmolality in blood plasma
Present study:
- what kind of needle was used?
18 gauge
Present Study Results:
- How many sharks were examined?
24
Present study Results:
- What were things that were found to not influence stress response/ show differences?
- shark size had no effect on stress response
- ## no differences measured between sexes (only 3 females were in group….not surprising since they segregate by sex…probably just a few stragglers from another group)
Present study Results:
- All blod sampling was obtained within __ minutes of hooking. No difference was found between what?
- 3mins
- initial levels and the time it took to get samples
L> first three minutes were pretty much standard therefore maybe it is baseline… also this indicates that these animals have a quick increase in stress.
Present Study Results:
- Glucose levels? How many peaks?Why?
- they increased 40% from the 15 min sample to the 60 min one.
- there were two large peaks…and they relatively plateaued afterwards ..likely due to the release of hormones!
Present study Results:
- Lactate levels? What do all studies point to in regards to these levels? What is mysterious about it?
- rose in a linear fashion
L> it seemed to be the most important indicator of stress response in sharks….all studies point to this.
L> we don’t know what happens later since they only go to a certain point prior to release
Present study Results:
- what was found to be a key factor in determining the survival of the shark once it is released? (2)
- lactic acid levels
- glucose as well
- those released with ugh glucose levels are more likely to survive vs low.
Present study Results:
- pH?
- it went from 6.86 to 6.78
L> this could be significant to sharks since it is on a log scale…. because we do not know the lethal limits in sharks
*** Humans” narrow range of 0.1 and anything outside of it for 3mins plus = dangerous
Present study Results:
- Hematocrit?
- there was no change in blood cell packed volume
Present study Results:
- When examining the graph with y= Plasma Glucose (mmol/L) and x= Time after capture (min) what do you notice?
- two peaks of glucose level
- One big increase in the first 15 minutes
- Second peak in the last 15 minutes
- study didn’t given any indication of what the shark was doing while these increases occurred