First discovered several years ago in North American lakes and rivers

Official Explanation

Evaluation of a Plan

In hopes of preventing the nonnative species northern snakehead from eliminating rare native fish species, wildlife officials have for the last three years been paying recreational fishers for each snakehead they catch. The northern snakehead has no predators in the area.

This question requires us to identify information that would be useful for determining whether the officials' plan will succeed.

Note that the plan has already been in effect. Nevertheless, we are given no information as to how well the plan has succeeded so far. To determine whether it is responsible to keep paying these fishers to catch northern snakehead, it is vital to understand whether the fishers' work up to this point has had any observable effect.

That is, it would be helpful to anyone who wants to determine whether the officials' plan is likely to succeed to have information about how the numbers of rare native fish species have been changing during that time.

A. This information would be useful for determining whether there may be alternative ways of reducing the northern snakehead population. However, it is not useful for determining whether the plan in question is likely to be successful.

B. Correct. As noted above, this information would be helpful in assessing whether the officials' plan is likely to succeed. If the numbers of rare native fish species have stayed constant or even declined throughout the period that the plan has been in place, it seems unlikely that the plan will ultimately be successful.

C. This information may provide a small amount of information as to how great a threat the northern snakehead might pose, but not much. For one thing, in its native region, the snakehead likely preys on different species from those in the region in question. More importantly, however, is the fact that this information is simply not useful to determining whether the officials' plan is likely to work in the region in question.

D. This might be useful for determining whether fishers have been motivated by the plan. This could potentially be useful for determining whether the plan will work; after all, the plan will not likely work if very few northern snakeheads are actually removed. Nevertheless, it is not as useful as noting the changes in the native fish population since the plan first went into effect.

E. Determining whether there are other threats to the rare native fish species would tell us whether the plan, if successful, is sufficient to save the rare fish species. Still, it is not useful in determining whether that plan is likely to be successful.

The correct answer is B.

First discovered several years ago in North American lakes and rivers, the northern snakehead is a nonnative fish with no local predators. - The snakehead is not native to the water bodies it was first discovered in. There are no local animals that prey on the snakehead.

To keep the northern snakehead's population from growing, for the past three years wildlife officials have been paying recreational fishers for each northern snakehead they catch. - Wildlife officials are trying to keep the snakehead’s population in check (since there are no local predators which could have kept its population in check). For this, they have been paying fishers per snakehead caught.

In this way, the officials hope to stop the northern snakeheads from eliminating rare native fish species. - The officials are going through this plan in order to try to stop snakeheads from eliminating rare native fish species.

Gist: The snakehead has no local predators. Wildlife officials hope to stop the snakehead from eliminating rare native species (goal). For this, they are trying to keep its population in check by paying fishers to catch snakehead (plan).


What data will help us evaluate the likelihood that the plan will succeed in achieving its goal?

In order to evaluate the plan, two questions come to mind:

• Is paying the fishers making a significant impact on the snakehead’s population growth?
• Is this impact helping reduce the decline of native fish species population?

Let’s understand these: what if the fishers are not incentivised enough to fish for snakeheads? Maybe the fish are too difficult to catch, or they can fish some other species that get them better returns. Or, even if the fishers are incentivised, the cumulative capacity of the fishers to fish for snakeheads is too low to make any meaningful impact.

What defines ‘meaningful’? What if the population of snakeheads is so huge compared with the rare native fish species, or what if each snakehead preys on a disproportionately large number of fish? In such a scenario, even if the snakehead population is stopped from growing, the goal may not be achieved.

A. Whether the northern snakehead's population in local lakes and rivers could be reduced by introducing predators from its native habitat
Incorrect. We’ve been asked to evaluate the likelihood that the ‘given plan’ will succeed. Whether another plan would work does not help evaluate the likelihood of success of the given plan.

This is a very common answer choice in a plan & goal question. Say John wishes to lose weight. In order to lose weight, he considers going on a keto diet. In order to evaluate whether keto diet will help him lose weight, we’ll not get into determining whether Atkins diet will work for him. Whether keto works or not is independent of whether something else works.

B. How local population numbers of rare native fish species have been changing since the wildlife officials started paying recreational fishers to catch northern snakeheads
Correct. Has there actually been an upward trend? If the local rare fish population continues to diminish, despite the plan being active, the plan will probably not be successful. On the other hand, if the local population has started showing growth (or stabilizing), the plan is probably working. Determining this would be useful to evaluate the likelihood that the plan will succeed.

C. Whether the fish species on which the northern snakehead preys in regions to which it is native and in which it is abundant have become significantly depleted in recent decades
Incorrect. This is a complicatedly worded statement. This option talks about the fish species on which the snakehead preys in its native regions. The option asks us to consider whether those fish species have become depleted. We need to evaluate whether the plan (to pay fishers to catch snakehead) will succeed. How drastically snakehead preys on other species, and how well the other preyed population is able to cope is immaterial.

D. What total number of northern snakehead have been caught by recreational fishers since the wildlife officials began paying for them
Incorrect. This answer choice might look attractive. An absolute number of snakehead caught, however, does not give us an understanding of the success of the plan.

Say 1,000 snakeheads were caught. How does this impact the plan’s success? If there were 1200 snakeheads to begin with, the plan seems to be a success since a significant proportion of snakeheads have been caught. On the other hand, if there were 1,000,000 snakeheads to begin with, the plan seems to be a failure. Thus, an absolute number in isolation without knowing the size of the population does not get us anywhere.

E. Whether rare native fish species in the region face any threats to their survival other than the proliferation of northern snakehead
Incorrect. The goal is to ‘stop the snakeheads from eliminating rare native fish species’. Whether the fish species face other threats does not help us evaluate whether this particular goal will be met. If the goal had been to prevent the elimination of rare native fish species, this option would have made sense.


The goal in this passage was actually divided into two stages.
Officials decided to pay fishers to catch snakehead fish (plan)
→ To keep its population from growing (goal - stage 1)
→ to stop the snakehead from eliminating rare native species (goal - stage 2)

The final goal may not be achieved even if the interim goal is met. The final goal will certainly not be achieved if the interim goal is not met.


SC Notes: “rare native fish species” - this is an example of cumulative adjectives. The two adjectives - rare and native - make sense only in the given order, and no comma is used to separate them. One way to understand this: the adjective ‘rare’ modifies the phrase ‘native fish species’ and not ‘species’ separately. ‘Red fire truck’ is another example of such usage.

Some alternate ways to use multiple single-word modifiers:
tall, beautiful girl: both adjectives modify the noun. In such usage, the two adjectives are separated by a comma.
extremely beautiful girl: the adverb ‘extremely’ modifies the adjective ‘beautiful’ and the adjective ‘beautiful’ modifies the noun ‘girl’.


If you have any doubts regarding any part of this solution, please feel free to ask.

HI KarishmaB AndrewN

We need to evaluate the the success of the plan. So it would be fair to assume that reducing the snakehead fish actually helps with the native fish population. Keeping that in mind, the success of the plan can only be gauged if the number of snakehead fish caught did actually increase. If it is still the same, the plan to give incentives the the catchers has failed. If the number of fish caught is increased, the plan has been successful in motivating officials to catch snakehead fish.

I know you would say that the number of fish caught does not provide any info on the how the native populations have changed. But if we are questioning this, we are implying that the thought process that went behind the introduction of the plan is shaky and flawed. How can we question the logic of a plan and at the same time objectively measure its success? Are we actually analyzing the success of the plan or are we analyzing the grounds on which the plan is based ?

There is no option that says that we should evaluate how the number of snakeheads caught has changed over the 3 yrs (no option that says more snakehead are being caught or not because of the plan).
Option (D) mentions the total number of snakeheads caught in the 3 years. Let’s say that was 11,000. What does this tell you? Is the plan succeeding? Is the number of snakeheads decreasing or steady or is it actually increasing only since they proliferate very quickly? Knowing just the total number of snakeheads caught gives us no info.
Option (B) asks to evaluate how the rare fish species number is changing… if the number is steady or has been increasing in the last 3 years, we know the plan is working. Likely higher number of snakeheads are being caught due to the incentive.

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Why are you rejecting E? How can it be irrelevant? Both B & E could be useful to determine the success of plan. Now you'll say other threats are irrelevant. But what if there is some other predator of native fish that could ruin the plan

The goal is not to increase the number of rare native fish species; the goal is "to stop the northern snakeheads from eliminating rare native fish species". The plan is "pay recreational fishers for each northern snakehead they catch". Option E has no bearing on the goal.

KarishmaB GMATIntensive GMATNinja sayantanc2k chetan2u

While I understand why other options are wrong, I am still not able to accept B. Statement B just gives me the yearly figures and trend in population of the rare native fish. its given that "the officials hope to stop the northern snakeheads from eliminating rare native fish species". If I take option B to extremes:

1) +ve - The population of the rare native fish has been increasing. This doesn't imply that the plan has necessarily caused the increase. Maybe despite increasing population of and predation by snakeheads, other predators stopped consuming; Maybe the rare native fish were reproducing more rapidly. etc. So despite the plan failing, the numbers suggest otherwise.

2) -ve - The population of rare native fish has been decreasing. This also doesn't imply anything about predation by snakeheads. E.g., if the population of rare fish fell from 100 to 10, the predation by snakeheads may have fallen down from 50 fish to 10 fish, while alternative factors (lower spawning rates, lack of food, predation by other creatures etc.) may have accounted for the remaining decline of 80 fish. So despite the plan working, the numbers suggest otherwise.

Requesting your inputs
Thanks.

Hi,
You would be absolutely correct incase we were given option B as a part of the argument and we were to find flaws or we were to weaken the reasoning.
However, if you read the CRs question stem, you will realise that it always asks for the most useful/appropriate of the given options.So, you are to find the BEST POSSIBLE options.

You can also think of it this way - You have to select the question, the answer to which COULD help you figure out whether the plan is working. It doesn't need to imply that the plan is working (or not) and in most real like situations, it won't necessarily imply.

For option (B):
The population of the rare native fish has been increasing - Yeeaah! The plan could be working! Let's find out more.
The population of rare native fish has been decreasing - On no! Doesn't look like the plan is working! Let's find out more.
... and this much is enough!

No such indication comes from any other option.

­For the more esoteric people out there, I was contemplating when would we call such a multi-goal plan successful? 

Plan - Incentives for fishing snakeheads. 
Intermediate Goal - to stop snakehead no's from increasing. 
Ultimate/ Final Goal - to stop snakeheads from eliminating rare native species. 

Situation 1: Intermediate Goal Achieved AND Final Goal achieved - Plan is successful (obviously)
Situation 2: Intermediate Goal not achieved (snakehead no's are still increasing) AND Final Goal not achieved (snakeheads eliminate rn species.) - plan is not successful. (again obvious.)

Situation 3: Intermediate goal achieved (successfully stopped snakehead no's from increasing) BUT Final goal not achieved (snakeheads still eliminate rn species.) - I would say the plan was not successful. It did not realize it's ultimate goal. 

Situation 4a Intermediate goal not achieved but some snakeheads were caught (did not stop snakehead no's from increasing but some snakeheads were caught) AND Final goal was achieved (snakeheads did not eliminate rn species) - In this case, I suppose a case could be made that the plan was successful. After all, even if it did not stop the increase in the #s it did perhaps prevent an even bigger increase which could have eliminated the rn species. 

Situation 4b Intermediate goal not achieved, 0 snakeheads were caught BUT Final goal was still achieved. (snakeheads did not cause elimination of rn species.) - In this case, we could hardly call the plan successful right? I guess, it is possible to have a failed plan but achieved goal? 

Could GMATNinja , avigutman , ChiranjeevSingh , AnishPassi comment on Situation 3 and Situation 4 please? Thanks!!

Thanks for the explanation.

But I believe that the question asks us to evaluate the LIKELIHOOD that the plan will succeed. That means we should determine factor(s) that could affect the success of the plan at the time the plan not yet implemented.
(B) is more like to evaluate if the plan, after being implemented
(E) is to evaluate if snakehead is the reason for the decrease in native fish species, if not (have other factors), the plan is meaningless. Although I'm not 100% agree with this since the plan is to "stop the northern snakeheads from eliminating rare native fish species", but it looks more attractive than (B) for that reason

The plan is already in motion for the past 3 years. We have to see whether it will succeed. If the native fish species has started recovering then it is likely that the plan is working and will succeed. That is why (B) works.

Option (E) is irrelevant.
The aim of the plan is to "stop the northern snakeheads from eliminating rare native fish species."
The snakeheads should not eliminate rare native species. This plan does not have other predators of rare native species in its scope at all.

Felt like a close call between B and C at first.

Would like to understand the basis for eliminating C if the fish species that the Northern Snakehead preys on in the regions where it is native have a significant depletion in their population, we can determine the potency of the threat that Northern Snakeheads pose to our native fish species. However, that is not the issue at contention here, since we want to understand whether, if at all, paying fishermen to capture Northern Snakeheads would stop predation (implying that they are preying on the fish).

Even if the answer to C is yes, it just confirms that the threat is real, nothing about the likelihood of success of the officials' plans, which has no effect on the argument.

If the answer is no, the threat it poses is not real, which says that we would not need the plan to begin with, and nothing about the likelihood of the plan succeeding. Also, this would contradict an implicit premise in the argument.

Is this reasoning correct?