Marine biologists studying migratory blue whales observed a significant increase in whale calf survival rates in the North Atlantic over the past decade. The researchers hypothesized that strict international regulations limiting commercial ship speeds in feeding zones caused this increase by reducing lethal vessel strikes. However, critics claim that ocean warming altered krill distribution, concentrating prey in protected zones where whales naturally feed away from major shipping lanes.
Which of the following statements, if true, provide support for the researchers' hypothesis regarding the cause of the increased calf survival rates? Select all that apply.
- Acoustic tracking data shows that during the decade, vessel traffic volume remained constant, but average ship speeds decreased by 40 percent following regulation, coinciding directly with a sharp drop in documented calf collision injuries.Answer
- Satellite surveys revealed that krill density in non-regulated ocean zones increased at identical rates to krill density within the protected feeding zones over the ten-year period.Answer
- CNecropsy reports from washed-up whale calves during the decade indicated that malnourished calves were significantly more susceptible to vessel strikes than well-nourished calves.
- DCommercial shipping companies operating in the North Atlantic reported higher operational costs due to increased fuel consumption required to comply with speed limits.
- EThe implementation of ship speed regulations coincided with a regional moratorium on commercial fishing gear that significantly lowered calf entanglement rates.
Answer
The statements confirming a direct drop in collision injuries following speed reduction and demonstrating identical krill density across both regulated and unregulated zones both strengthen the researchers' hypothesis.
The researchers hypothesize that speed limits directly caused higher calf survival by preventing lethal ship strikes, while critics argue that krill shifts drew whales away from shipping lanes. The statement establishing that collision injuries dropped sharply after speed limits were introduced directly confirms the causal link between regulations and calf safety. The statement showing uniform krill growth across both regulated and unregulated waters refutes the critics' counter-hypothesis by demonstrating that prey distribution did not selectively concentrate whales away from shipping lanes. Together, these statements reinforce the primary argument.
Step-by-Step Solution
Key Concept
Strengthening Causal Arguments by Confirming Causal Mechanisms and Eliminating Alternative Explanations