Summary:
It has been observed that certain fish have had strange bites on them. These bite marks are from cookie-cutter sharks. They feed on crustaceans but they have also been known to take a bite out of much bigger fish, whales, and seals. After observing this, scientists set out to do a study in order to answer a few questions. The goals of this study were to see how the bites varied each season, see what species were targeted, and use the marks to identify the size of the cookie-shark.
The scientists were able to study the bite marks that the sharks made on fish from the Honolulu Fish Auction. They went their weekly for one year in order to collect data. The data was collected at the same time each week. They took the percentage of fish that were bite each week. They then used a sub-sample of fish in order to get a more in depth examination of the shark bites. The scars were classified as being new, partially-healed, and healed.
The fish most effected by bite marks were swordfish, opha, and bigeye and yellowfin tuna. Swordfish had the highest percent of fresh bites, followed by opah. Pacific blue marlins didn't have any bites from the cookie-cutter shark. Swordfish and opah also had the highest amounts of healed bites. Swordfish, bigeye tuna, and opah had consistent scaring throughout the year. The probability for some species varied throughout the year. Swordfish had the most bites per individual. Overall the data showed that swordfish were the most preyed upon along with the yellowfin and bigeye tuna, and the opah. The pacific blue marlin was not preyed upon.
Evaluation:
This article gave accurate information on the study. It gave specific data and explained how the study was carried out. The article was clear on why the study was being conducted, how it was, and what the results were. The article was concise in most parts but it did become repetitive at some points, like in the discussion. The article didn't stray from the topic however. The sentences weren't too wordy either. This study was ethical. The scientists did not harm any animals during this study. The study actually helps the fishermen because the cookie-cutter bites decrease the value of the fish, so if they know when the bites are more likely and what fish are more likely to get bitten they can base their fishing off the data. The article wasn't hard to read. Their were some parts that were difficult to read because of jargon. It was also lengthy to read. The reader satisfaction is moderate because it can be a very helpful study for fishermen and marine scientists. It could be hard for others to read. The article was organizes and not too hard to read though.
The intend purpose of this article was to inform scientists and fishermen the species most effected by cookie-cutter sharks, along with the seasonal patterns, etc. The article was meant for a low to high tech audience, mostly fishermen and marine scientists. The organization of the article was well done. The figures were properly introduced and the sections had effective headings.
Reference:
Papastamatiou, Y. P., Wetherbee, B. M., O'Sullivan, J., Goodmanlowe, G. D., & Lowe, C. G. (2010). Foraging ecology of Cookiecutter Sharks ( Isistius brasiliensis) on pelagic fishes in Hawaii, inferred from prey bite wounds. Environmental Biology Of Fishes, 88(4), 361-368. doi:10.1007/s10641-010-9649-2
Wednesday, May 1, 2013
"The Functional role of the caudal fin in the feeding ecology of the common thresher shark Alopias velpinus"
Summary:
This study was about the use of the tail fin of the thresher shark. It is known that sharks use their unique tails to give them lift as they move through the water. However, this species of shark has an unusually long tail. There has been evidence suggesting that the tail is also used as a feeding mechanism but it has not been observed or scientifically proven. This study was done to prove whether or not this hypothesis is correct.
The evidence in the past of these sharks using their tails as a feeding mechanism has been thresher sharks have been caught on long lines by their tails. This suggests that instead of biting their prey initially, the sharks use their tail before eating their prey. Using this evidence to create a hypothesis, scientists expected sharks to use their tails on their prey.
In order to test this hypothesis, scientists set out long lines with bait attached. Then they places a camera underwater in order to monitor how the sharks react to the bait. Mature and juvenile sharks were taped and both male and female. The sharks used their tails to strike before biting the bait. There were two different approaches the sharks used. The first approach was the shark undulated and their tails made a sinusoidal motion that hit the fish. This was observed in 59% of the strikes and resulted in a 47% success rate. The second most common motion was the lateral strike of the tail. This was observed 12 times and had a 92& success rate. These results confirmed the hypothesis.
Evaluation:
The article was accurate in describing the experiment and gave a detailed description of how they were able to preform the experiment. The article was clear and easy to follow. It stayed on the subject and didn't jump around. It gave support to the findings and used enough details to allow the reader to understand the experiment and the reason behind it. The article for the most part was concise. It did go into a lot of detail about the programs used and how they edited the film of the sharks. Overall, the authors didn't stray from the main points and their sentences weren't wordy. The experiment was ethical. No sharks were harmed because they didn't use hooks on the long lines. No fish were harmed either because they didn't use live bait. The readability was not difficult. Some words a lay audience would not understand but I was able to understand them as a freshman marine science major. The sentences weren't complex and it didn't take long to read. Overall, as a reader I'm satisfied with the article. It wasn't too difficult to read and all the information was presented.
The purpose of this article was to inform the scientific community that it is proven that thresher sharks do use their tails in prey. The audience would be marine scientist and shark biologist. The audience is not lay, it would probably be a low to high tech audience. The document was not organized very well. There were no headings and the figures were not introduced in the text.
Reference:
Aalbers, S. A., Bernal, D. D., & Sepulveda, C. A. (2010). The functional role of the caudal fin in the feeding ecology of the common thresher shark Alopias vulpinus. Journal Of Fish Biology, 76(7), 1863-1868. doi:10.1111/j.1095-8649.2010.02616.x
This study was about the use of the tail fin of the thresher shark. It is known that sharks use their unique tails to give them lift as they move through the water. However, this species of shark has an unusually long tail. There has been evidence suggesting that the tail is also used as a feeding mechanism but it has not been observed or scientifically proven. This study was done to prove whether or not this hypothesis is correct.
The evidence in the past of these sharks using their tails as a feeding mechanism has been thresher sharks have been caught on long lines by their tails. This suggests that instead of biting their prey initially, the sharks use their tail before eating their prey. Using this evidence to create a hypothesis, scientists expected sharks to use their tails on their prey.
In order to test this hypothesis, scientists set out long lines with bait attached. Then they places a camera underwater in order to monitor how the sharks react to the bait. Mature and juvenile sharks were taped and both male and female. The sharks used their tails to strike before biting the bait. There were two different approaches the sharks used. The first approach was the shark undulated and their tails made a sinusoidal motion that hit the fish. This was observed in 59% of the strikes and resulted in a 47% success rate. The second most common motion was the lateral strike of the tail. This was observed 12 times and had a 92& success rate. These results confirmed the hypothesis.
Evaluation:
The article was accurate in describing the experiment and gave a detailed description of how they were able to preform the experiment. The article was clear and easy to follow. It stayed on the subject and didn't jump around. It gave support to the findings and used enough details to allow the reader to understand the experiment and the reason behind it. The article for the most part was concise. It did go into a lot of detail about the programs used and how they edited the film of the sharks. Overall, the authors didn't stray from the main points and their sentences weren't wordy. The experiment was ethical. No sharks were harmed because they didn't use hooks on the long lines. No fish were harmed either because they didn't use live bait. The readability was not difficult. Some words a lay audience would not understand but I was able to understand them as a freshman marine science major. The sentences weren't complex and it didn't take long to read. Overall, as a reader I'm satisfied with the article. It wasn't too difficult to read and all the information was presented.
The purpose of this article was to inform the scientific community that it is proven that thresher sharks do use their tails in prey. The audience would be marine scientist and shark biologist. The audience is not lay, it would probably be a low to high tech audience. The document was not organized very well. There were no headings and the figures were not introduced in the text.
Reference:
Aalbers, S. A., Bernal, D. D., & Sepulveda, C. A. (2010). The functional role of the caudal fin in the feeding ecology of the common thresher shark Alopias vulpinus. Journal Of Fish Biology, 76(7), 1863-1868. doi:10.1111/j.1095-8649.2010.02616.x
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