Parlands alligator population has been declining in recent years Ver1

IMO D...
Since fishe's eggs used to hatch in the wholes dug by alligators. But since the alligators population has started decreasing, so there is less number of holes dug by alligators, which in turn has an effect on less no of eggs being hatched.

Parland’s alligator population has been declining in recent years, primarily because of hunting. Alligators prey heavily on a species of freshwater fish that is highly valued as food by Parlanders, who had hoped that the decline in the alligator population would lead to an increase in the numbers of these fish available for human consumption. Yet the population of this fish species has also declined, even though the annual number caught
for human consumption has not increased.

Which of the following, if true, most helps to explain the decline in the population of the fish species?

A. The decline in the alligator population has meant that fishers can work in some parts of lakes and rivers that were formerly too dangerous.....where they can work is not important.....rather why did the fish decline?
B. Over the last few years, Parland’s commercial fishing enterprises have increased the number of fishing boats they use....but annual number caught has not increased....let them increase boats
C. Many Parlanders who hunt alligators do so because of the high market price of alligator skins, not because of the threat alligators pose to the fish population.........thats fine.... but why did the fish decline?
D. During Parland’s dry season, holes dug by alligators remain filled with water long enough to provide a safe place for the eggs of this fish species to hatch.....clearly a winner as it gives cause for reduction in fishes..... CORRECT
E. In several neighboring countries through which Parland’s rivers also flow, alligators are at risk of extinction as a result of extensive hunting....BUT why did the fish decline?

I think only option B can make test takers fool.

B says number of fishing boats increases. Now no of boats increase doesn't mean the catch has increased. There may be other reasons for increasing the fishing boats.

On the other hand D shows how have the habitats of fish been destroyed by the killing of alligator. If fish can't get safe place for their eggs, the no of fish will eventually decrease.

Even though I have selected the corect answer in both OG13 and in the altered version, I don't understand , why did you change the answer choices. Official questions are best structured, and I don't see any reason to alter them.

We need here some connection between decreasing number of alligators and freshwater fishes + the fact that alligators prey heavily on that type of fishes. This is a Resolve the Paradox Question - so we don't have a conclusion here. In this type of questions both sides are factually correct and we need to explain how the situation came into being or add a piece of Information showing how the two parts can coexist (see CR Bible). To resolve the paradox we must adress ALL the facts -> decreasing number of alligators and fish species + the annual number of fishes caught for human consumption has not increased.

A. The decline in the alligator population has meant that fishers can work in some parts of lakes and rivers that were formerly too dangerous. -> in the argument is clearly stated, the number of fishes for human consumption doesn't change
B. Over the last few years, Parland’s commercial fishing enterprises have increased the number of fishing boats they use. -> in the argument is clearly stated, the number of fishes for human consumption doesn't change
C. Many Parlanders who hunt alligators do so because of the high market price of alligator skins, not because of the threat alligators pose to the fish population. -> it's out of scope and btw. doesn't explain the decreasing number of fish species
D. During Parland’s dry season, holes dug by alligators remain filled with water long enough to provide a safe place for the eggs of this fish species to hatch. -> CORRECT. #of Alligators decreases -> #of the holes decreases -> fewer safe places for the eggs to hatch -> fewer fish species.
E. In several neighboring countries through which Parland’s rivers also flow, alligators are at risk of extinction as a result of extensive hunting. -> It doesn't explain the decreasing number of fish species

OG 13 Answers:
A. The decline in the alligator population has meant that fishers can work in some parts of lakes and rivers that were formerly too dangerous -> in the argument is clearly stated, the number of fishes for human consumption doesn't change
B. Over the last few years, Parland’s commercial fishing enterprises have increased the number of fishing boats they use -> in the argument is clearly stated, the number of fishes for human consumption doesn't change
C. The main predator of these fish is another species of fish on which alligators also prey --> CORRECT. #Alligators goes down --> #main Predator fish type goes up --> #freshwater fish species goes down.
D. Many Parlanders who hunt alligators do so because of the high market price of alligator skins, not because of the threat alligators pose to the fish population -> it's out of scope and btw. doesn't explain the decreasing number of fish species
E. In several neighboring countries through which Parland’s rivers also flow, alligators are at risk of extinction as a result of extensive hunting -> It doesn't explain the decreasing number of fish species

A - decline in alligator population means fishers can work in parts of lakes & rivers that were formerly too dangerous...if fishers can work in more areas of the lake, can it not be inferred that they could catch more freshwater fish? it doesn't have to be for human consumption, this could be "game fish" like swordfish, etc. This could be correct.

B - Commercial fishing enterprises increasing the # of fishing boats they use could be correct b/c commercial fishing not discussed in the passage...passage only refers to the annual # caught for human consumption.

* I don't like (D). Are these "holes" that provide a safe place for eggs to hatch the ONLY safe places for these eggs to hatch? We're told that alligators prey heavily on this species but are not told about anything else in the passage that could decrease the number of these fish.
- No talk about toxic chemicals being poured into the lake to kill the alligators or
- a virus that spread throughout the lake that kills these fish.

This question really angers me - need someone to break apart my argument here and show me how I'm incorrect.

GMATNinjaTwo GMATNinja

Awesome explanation.


Usually you also point out to stress on modifiers/ minute details while reading argument.
But is there any significant role of highlighted portion?

adkikani, glad to see that you're paying attention to the author's word choice and to the details/modifiers!

In this case, the highlighted portion really just gives us some background information to make sense of this answer choice. Water levels will go down during the dry season, reducing the number of safe places for the eggs to hatch. But despite decreased water levels, the alligator holes remain filled.

If we weren't told that there was a dry season, we might not understand why the holes are necessary. Given the highlighted portion, we understand that water levels can decrease seasonally, and this helps explains why the alligator holes are so important.

I hope that helps!

GMATNinjaTwo


I have different view point than you.

If you see argument again, we already know that alligator population is decreasing because of hunting.
So in absence of alligators, less holes will be dug
and hence fish species WILL NOT be able to hatch in absence of holes and water.

We DO NOT need timing of when the holes are filled with water for fish species to hatch as mentioned by noun modifier
- During Parland’s dry season.

Is my reasoning valid?

Yes, we know that the alligator population (and hence the holes) are decreasing.

Again, I think the highlighted phrase simply provides some context. Picture a body of water whose water is at its highest point. Now, as the water level goes down during the dry season, the fish might have a problem finding a place for the eggs. Luckily, pools of water remain in those alligator holes, providing a safe place for the eggs. Yes, the holes are there regardless of the season, but if the water levels never decreased, the holes might not be needed.

Parland’s alligator population has been declining in recent years, primarily because of hunting. Alligators prey heavily on a species of freshwater fish that is highly valued as food by Parlanders, who had hoped that the decline in the alligator population would lead to an increase in the numbers of these fish available for human consumption. Yet the population of this fish species has also declined, even though the annual number caught for human consumption has not increased.

Main Group: Alligator population and Fish Species that Alligator prey heavily on.
Main Issue: Fewer Alligator, Fewer Fish

Why the heck does diminishing Alligator population leading to the decrease of Fish population? Alligator eats fish; There must be more fish if there are fewer alligators. What is the relation between these two?

Which of the following, if true, most helps to explain the decline in the population of the fish species?

Modifier plays such a heavily role in these kind of answer choices. The reasoning clearly stated that "the annual number caught for human consumption has not increased." Whether fishers can work there or not should not affect that statement. (A) is out.
More boats. Then why the number caught has not been increased? (B) is out.
This, if anything, implies that there should be more fish, making the paradox even harder. (C) is out.
Great. Now this answer is discussing about the relationship between fish and alligators. Let's dive in for more: The choice says that this fish species depend on alligators' holes in order to sustain their eggs. The fewer alligators are , the fewer the holes are. Hence, there is lower chance that the eggs of this fish species can hatch, resulting in the decrease of this fish species' population. Hang on to this.
This is again not discussing the fish species. (E) is out.

Only (D) is left. (D) is our choice.

IMHO, had it been an indicator of a dry season in the prompt, choice D would have been a stronger strengthener. To be honest, if this question were not from the OG, I would virtually suspect the quality of the question. I would appreciate experts' comments on this matter.

GMATNinja, MentorTutoring, VeritasKarishma

Kudos if you liked this post!

Hello, tyildirim92. I think you are likely reading too closely through each answer choice when a blunter approach would spare you the headache. (I know from my shaken-confidence-on-CR days.) Your task here is to figure out why killing alligators, perhaps in addition to other factors that may be curtailing the alligator population, has not led to an increase that the locals had anticipated in the number of a species of freshwater fish that alligators prey upon. A key detail comes at the end of the passage that rules out certain logical explanations that pop up in different answer choices: the annual number [of this fish species] caught for human consumption has not increased. If this is true, then (A) and (B) are out, since the suggestion is that expanded fishing operations, whether small or large in scale, could explain the decline. It would take an extra, unmentioned step to justify either answer, such as saying that the commercial vessels in (B) leak a certain toxin into the water that kills this delicate fish. Of the three remaining answer choices, (C) provides an alternative motivation for Parlanders to hunt alligators—not what we are after—and (E) invokes neighbors, providing zero insight into the issue at hand. Choice (D) is the only one that puts the facts together in a way that makes logical sense: if the alligators are responsible for indirectly ensuring the propagation of the very species of fish it preys upon, and those alligators are now in decline, then we can appreciate why Parlanders are not enjoying a bounty of fish.

The GMAT™ is big on this young-of-a-species concept in CR. I am not sure why. This question made me think of a few others that fall into somewhat similar lines of reasoning: 1) Climate change and 2) Turtle eggs.

All I can suggest to you is that you look to follow linear thinking, a streamlined method, as you approach CR passages and questions. I would not have anticipated (D) as the most reasonable answer choice (which is why I typically avoid the so-called pre-thinking step), but it is the only one that speaks directly to the matter at hand, and the dry season hardly matters. Why are there not more fish if human overfishing is not the problem? Why is the decline in the alligator population significant? These are the types of questions, pre-thinking or no, you need to come to terms with. You can only go by what is on the screen in front of you.

I hope that helps. Thank you for tagging me, and good luck with your studies.

- Andrew

tyildirim92

Note that you are confusing two different versions of the options.

Both

(C) The main predator of these fish is another species of fish on which alligators also prey.
and
(D) During Parland’s dry season, holes dug by alligators remain filled with water long enough to provide a safe place for the eggs of this fish species to hatch.

are perfectly good answers.

One version of the options is:
A. The decline in the alligator population has meant that fishers can work in some parts of lakes and rivers that were formerly too dangerous.
B. Over the last few years, Parland’s commercial fishing enterprises have increased the number of fishing boats they use.
C. The main predator of these fish is another species of fish on which alligators also prey.
D. Many Parlanders who hunt alligators do so because of the high market price of alligator skins, not because of the threat alligators pose to the fish population.
E. In several neighboring countries through which Parland’s rivers also flow, alligators are at risk of extinction as a result of extensive hunting.

and the other is:
(A) The decline in the alligator population has meant that fishers can work in some parts of lakes and rivers that were formerly too dangerous.
(B) Over the last few years, Parland’s commercial fishing enterprises have increased the number of fishing boats they use.
(C) Many Parlanders who hunt alligators do so because of the high market price of alligator skins, not because of the threat alligators pose to the fish population.
(D) During Parland’s dry season, holes dug by alligators remain filled with water long enough to provide a safe place for the eggs of this fish species to hatch.
(E) In several neighboring countries through which Parland’s rivers also flow, alligators are at risk of extinction as a result of extensive hunting.


Note that both answers cannot appear together and they do not. Only one option can be correct and so it is. The highlighted option is correct in each version.

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