AP Environmental Science Quiz: Impacts Of Overfishing

What this quiz covers

This quiz focuses on Impacts Of Overfishing, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Environmental Science.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Chemical damage kills non-target organisms and corals, degrading habitat and reducing biodiversity beyond the targeted fish removal. (correct answer)
2. Cyanide increases dissolved oxygen, causing oxidative stress only in predators and leaving reef communities otherwise unaffected.
3. Cyanide acts as a fertilizer, increasing algal growth and thereby increasing reef fish abundance and ecosystem stability.
4. Cyanide reduces ocean temperature locally, leading to coral bleaching because corals require warmer water to survive.

Explanation: Using cyanide in fishing stuns target fish but causes widespread chemical damage, killing non-target organisms and degrading habitats like corals. This reduces biodiversity and disrupts reef ecosystems beyond just the removed fish. Corals, essential for reef structure, suffer mortality, leading to habitat loss for many species. The practice highlights the collateral damage of destructive fishing methods. Sustainable alternatives are needed to protect marine life. Overfishing via such methods accelerates ecosystem decline.

Question 2

1. Predators can stabilize prey populations by preventing overcrowding; removing predators may increase density-dependent stress and outbreaks. (correct answer)
2. Predators always reduce biodiversity, so removing them should permanently increase prey populations without negative feedbacks.
3. Disease only affects predators, so prey crashes must be caused by toxins introduced by fishing gear into the water.
4. Starvation occurs because fewer predators means less oxygen, and prey require predators to oxygenate water through swimming.

Explanation: Predators regulate prey populations, preventing overabundance that leads to resource depletion or disease. Removing predators allows prey booms followed by crashes due to density-dependent factors. This shows top-down control's role in stability. Reintroducing predators can restore balance. Overfishing disrupts these dynamics. Understanding this aids ecosystem management.

Question 3

1. low reproductive rate and long generation time, so populations recover slowly after harvest reduces breeding adults. (correct answer)
2. high fecundity and short lifespan, so individuals reproduce rapidly and are removed before contributing to the gene pool.
3. a producer trophic role, so harvesting directly reduces primary productivity and collapses the entire ecosystem immediately.
4. a dependence on freshwater, so any harvest in marine waters causes instant mortality from osmotic shock.

Explanation: Species with low reproductive rates and long generation times, like sharks, recover slowly from overfishing. They produce few offspring, making populations vulnerable to harvest. In contrast, fast-reproducing species like sardines rebound quicker. Life history traits determine susceptibility. Management must account for these differences. Protecting slow-growers prevents extinction risks.

Question 4

1. Lost or abandoned gear continues capturing and killing organisms unintentionally, increasing mortality even without active fishing effort. (correct answer)
2. Predators consume fishers' catch at the surface, reducing profits and causing fishers to increase effort to compensate.
3. Fish become invisible to sonar after repeated net exposure, making them appear absent and leading to false stock assessments.
4. Fish migrate through underwater caves, avoiding nets and causing sudden, unexplained drops in catch per unit effort.

Explanation: Ghost fishing occurs when lost or abandoned gear continues to trap and kill marine life, adding unintended mortality without active fishing. This prolongs overfishing impacts, affecting non-target species and ecosystems. Bans on gear like drift nets aim to prevent this. Cleanup efforts are also crucial. It contributes to biodiversity loss. Addressing ghost fishing is key to marine conservation.

Question 5

1. Remove harmful subsidies and set science-based catch limits, reducing effort and aligning harvest with sustainable population growth. (correct answer)
2. Increase subsidies so fleets can travel farther, spreading fishing pressure evenly and preventing local depletion of stocks.
3. Ban seafood imports, which automatically increases domestic fish populations by reducing demand for local fisheries.
4. Require larger boats, because larger vessels catch fish more efficiently and reduce total time spent fishing.

Explanation: Subsidies lower fishing costs, increasing effort and overexploitation. Removing them reduces pressure, while catch limits ensure sustainability. This aligns harvest with stock growth. Science-based policies prevent decline. Addressing economic incentives is key. Overfishing often stems from such market failures.

Question 6

1. Predation on urchins increases, reducing grazing pressure and allowing kelp forests to recover, improving habitat for many species. (correct answer)
2. Kelp photosynthesis increases predators directly by providing oxygen bubbles that predators consume as a food source.
3. Urchins evolve into kelp due to reduced fishing pressure, converting grazers into producers and expanding kelp coverage.
4. Predators reduce sunlight penetration, shading urchins and causing them to starve, which indirectly increases kelp.

Explanation: Increased predators in protected areas control grazer populations like urchins through predation. Fewer urchins mean less grazing on kelp, allowing forests to recover. Kelp provides habitat, boosting biodiversity. This is a positive trophic cascade from protection. Reserves demonstrate recovery potential. Overfishing's reversal highlights conservation benefits.

Question 7

1. Population bottlenecks from overharvest reduce effective population size, increasing inbreeding and loss of alleles through genetic drift. (correct answer)
2. Increased gene flow from distant populations always decreases genetic diversity by homogenizing alleles across the entire species range.
3. Higher mutation rates caused by fishing gear introduce harmful alleles, which increases genetic diversity and stabilizes populations.
4. Reduced predation increases population size, which necessarily decreases genetic diversity because more individuals share fewer alleles.

Explanation: Overfishing creates population bottlenecks, reducing effective population size and genetic diversity through drift and inbreeding. This makes species less adaptable to changes like disease or climate. Loss of alleles can impair long-term survival. Monitoring genetic health is key in management. Protecting populations prevents these genetic impacts. This highlights overfishing's effects beyond abundance.

Question 8

1. Trophic cascade increases grazers that damage seagrass, reducing biomass and sediment carbon burial, lowering long‑term blue carbon storage. (correct answer)
2. Predator removal increases seagrass photosynthesis by reducing shade from fish schools, increasing carbon storage in sediments.
3. Overfishing increases carbonate precipitation, converting organic carbon into limestone and permanently increasing seagrass carbon storage.
4. Seagrass declines because fishing reduces atmospheric carbon dioxide, limiting photosynthesis and causing global seagrass loss.

Explanation: Overfishing predators triggers trophic cascades, increasing grazer populations that damage seagrass, reducing biomass and carbon burial in sediments. This lowers blue carbon storage, affecting climate regulation. Seagrasses are vital for coastal carbon sequestration. Protecting predators maintains balance. Restoration efforts can reverse damage. Overfishing thus impacts carbon cycles indirectly.

Question 9

1. Require acoustic pingers and net visibility modifications, and restrict fishing during peak seabird foraging times to reduce entanglement. (correct answer)
2. Increase mesh size so more seabirds can pass through, which also increases catch efficiency for target fish.
3. Remove all catch limits because higher fish abundance will distract seabirds from nets and lower entanglement rates.
4. Add fertilizer to coastal waters to increase plankton blooms, moving seabirds offshore and away from fishing activity.

Explanation: Gillnets can entangle seabirds as they dive for fish, increasing mortality in foraging areas. Management actions like acoustic pingers emit sounds to deter birds, while net modifications improve visibility. Restricting fishing during peak foraging times further reduces risks. These measures help minimize bycatch without halting fisheries entirely. They demonstrate adaptive strategies to address overfishing's non-target effects. Protecting seabirds supports overall marine biodiversity and ecosystem health.

Question 10

1. Artificial selection favors earlier maturation at smaller sizes because large, late-maturing individuals are removed before reproducing as often. (correct answer)
2. Genetic drift increases body size because population bottlenecks always favor larger individuals that can store more energy for migration.
3. Mutualism with cleaner fish is disrupted, directly causing groupers to mature earlier through reduced parasite removal rates.
4. Carrying capacity rises after fishing, so density-dependent competition increases and forces individuals to delay reproduction until larger.

Explanation: Overfishing that selectively targets the largest individuals in a population, such as groupers, can drive evolutionary changes through artificial selection. Larger, later-maturing fish are removed before they can reproduce multiple times, leaving smaller, earlier-maturing individuals to pass on their genes. Over generations, this shifts the population toward smaller average sizes and younger ages at maturity. This change reduces the overall productivity and resilience of the fish stock, as smaller fish produce fewer offspring. Such fishing-induced evolution highlights the long-term genetic impacts of overfishing beyond just population decline. Effective management, like size limits, can help mitigate these effects and preserve natural traits.

Question 11

1. Allowing individuals to reproduce at least once before harvest increases recruitment and helps maintain a sustainable breeding population. (correct answer)
2. Minimum size limits increase biodiversity by ensuring predators only eat small lobsters, preventing trophic cascades in kelp forests.
3. Minimum size limits reduce ocean acidification because larger lobsters store more carbon in shells, raising seawater pH.
4. Minimum size limits prevent habitat destruction by stopping traps from contacting the seafloor and crushing benthic organisms.

Explanation: Minimum size limits ensure fish reach reproductive maturity before harvest, allowing at least one spawning cycle. This boosts recruitment and sustains populations. It counters size-selective fishing pressures. Such rules are vital for species with high juvenile mortality. They promote larger, more fecund adults in the stock. This strategy mitigates overfishing by preserving breeding potential.

Question 12

1. Increased prey density and competition after predator release favors earlier reproduction and smaller size, a density-dependent life history shift. (correct answer)
2. Reduced sunlight after predator removal decreases photosynthesis, forcing prey fish to mature earlier due to limited oxygen production.
3. Predator removal increases salinity, which directly shortens prey lifespans and forces earlier reproduction in all marine species.
4. Overfishing increases mutation rate in prey, guaranteeing smaller size and earlier reproduction regardless of ecological conditions.

Explanation: Removing predators increases prey density, triggering density-dependent shifts toward smaller size and earlier reproduction to cope with competition. This is an evolutionary response to overfishing pressures. It can reduce overall productivity. Protecting predators prevents such changes. Ecosystems adapt but at a cost to resilience. Overfishing alters life histories profoundly.

Question 13

1. Protecting reproductive individuals increases recruitment and future population size by allowing more adults to spawn successfully. (correct answer)
2. Closed seasons increase genetic mutations, which quickly creates more salmon and offsets fishing mortality within one generation.
3. Spawning bans reduce river flow, preventing eggs from drifting and increasing survival by keeping them stationary on gravel.
4. Closed seasons eliminate predators like bears and seals, which depend on salmon and therefore must decline without access.

Explanation: Spawning seasons are critical for fish reproduction, and banning fishing then protects breeding adults. This increases egg production and recruitment, aiding population recovery. It prevents disruption of spawning behaviors and aggregations. Such temporal closures are a common tool in fishery management. They help maintain genetic diversity and stock structure. This approach mitigates overfishing by focusing on reproductive success.

Question 14

1. Reduce incidental mortality of non-target species to protect populations and maintain ecosystem integrity while continuing target harvest. (correct answer)
2. Increase dolphin harvest to reduce competition with fishers for tuna, thereby increasing tuna abundance and catches.
3. Increase ocean productivity by forcing dolphins to migrate, which increases nutrient upwelling and raises fish biomass.
4. Eliminate the need for quotas because protecting dolphins guarantees tuna stocks cannot be overfished under any conditions.

Explanation: Bycatch of non-target species like dolphins in fisheries increases mortality and threatens populations, disrupting ecosystem integrity. Rules requiring nets to be set only when dolphins are absent aim to reduce incidental deaths while allowing target harvest. This protects biodiversity without halting fishing. Effective bycatch mitigation supports sustainability. Overfishing exacerbates bycatch issues through intensified effort. Such measures highlight the need for selective practices.

Question 15

1. Progressive depletion of higher trophic species and increased harvest of lower trophic species, consistent with fishing down the food web. (correct answer)
2. Rapid ocean warming increased trophic level of catch, because warm water always supports more apex predators than cold water.
3. Improved gear selectivity increased capture of apex predators, raising trophic level, but reporting errors reversed the trend.
4. Nutrient pollution reduced plankton, forcing fish to become herbivores, which increases trophic level of catch over time.

Explanation: Declining mean trophic level in catches indicates fishing down the food web, where overfishing depletes higher predators, shifting harvest to lower levels. This reflects ecosystem simplification and biodiversity loss. It's a sign of unsustainable practices. Monitoring trophic levels aids assessment. Recovery involves protecting apex species. Overfishing drives this global trend.

Question 16

1. Stock depletion: declining catch per unit effort suggests lower abundance, meaning more effort is required to catch the same amount. (correct answer)
2. Improved efficiency: lower catch per unit effort proves fishers are becoming more skilled and need fewer fish to meet quotas.
3. Carrying capacity increasing: declining catch per unit effort indicates the population is growing too fast and dispersing widely.
4. Ocean acidification reversal: fewer fish caught means fewer shells dissolve, raising pH and decreasing fish vulnerability to nets.

Explanation: Declining catch per unit effort (CPUE) is a key indicator of stock depletion in overfished populations, as more effort is needed to catch fewer fish. This reflects lower abundance due to excessive harvesting outpacing reproduction. Monitoring CPUE helps assess fishery health and signals the need for reduced quotas. Ignoring this can lead to collapse. Recovery requires cutting effort to allow rebuilding. This metric underscores the economic and ecological costs of overfishing.

Question 17

1. Population size declines below $K/2$, reducing growth rate and risking collapse because reproduction cannot offset removals. (correct answer)
2. Population stabilizes at carrying capacity because harvesting increases resources, eliminating density dependence and maximizing growth.
3. Population increases because removing individuals always reduces competition, guaranteeing higher net growth regardless of harvest rate.
4. Population immediately evolves into a different species, preventing collapse by occupying a new trophic niche in the ecosystem.

Explanation: Fish populations often follow logistic growth models, where growth is fastest at half the carrying capacity ($K/2$) and slows as it approaches $K$. Maximum sustainable yield (MSY) is the highest harvest rate that allows the population to replace itself indefinitely. If harvesting exceeds MSY, the population drops below $K/2$, reducing growth rates and making recovery difficult. Continued overharvest can lead to collapse as reproduction fails to offset removals. This underscores the importance of science-based quotas to prevent depletion. Understanding population dynamics helps in avoiding irreversible overfishing impacts.

Question 18

1. Reduced fish predation and competition allows jellyfish blooms, which can lower fish recruitment by consuming eggs and larvae. (correct answer)
2. Jellyfish dominance increases coral calcification because jellyfish release calcium carbonate that settles onto reefs as building material.
3. Jellyfish dominance increases dissolved oxygen permanently because jellyfish photosynthesize and add oxygen to the water column.
4. Jellyfish dominance eliminates eutrophication because jellyfish remove nitrogen from water by converting nitrate to nitrogen gas.

Explanation: Overfishing predatory fish can allow jellyfish populations to boom due to reduced competition and predation. Jellyfish then consume fish eggs and larvae, hindering recruitment. This shift can create a feedback loop favoring jellyfish dominance. Ecosystems become less productive for fisheries. Protecting fish stocks prevents such regime shifts. This illustrates trophic imbalances from overfishing.

Question 19

1. Biomagnification reduces scallop survival because toxins move from sharks into rays, increasing ray toxicity and scallop mortality.
2. A trophic cascade occurs as removal of apex predators releases mesopredators, increasing predation on lower trophic levels like scallops. (correct answer)
3. Competitive exclusion occurs because rays outcompete sharks for scallops, causing sharks to switch prey and then disappear.
4. Ecological resilience increases because fewer sharks means the ecosystem becomes simpler and therefore more stable against disturbances.

Explanation: In marine ecosystems, overfishing apex predators like sharks can lead to a trophic cascade by releasing mesopredators from control. With fewer sharks, populations of rays increase because they face less predation and competition. These abundant rays then prey more heavily on lower trophic levels, such as scallops, causing their populations to decline. This imbalance demonstrates how removing top predators can ripple through the food web, affecting commercially important species. Biodiversity and ecosystem stability suffer as a result, emphasizing the need for holistic management approaches. Protecting apex predators helps maintain natural checks and balances in the ocean.

Question 20

1. Food limitation for higher trophic levels may reduce seabird and marine mammal reproduction and survival, altering community structure. (correct answer)
2. Seabird populations increase because fewer prey fish forces birds to eat more, improving their nutrition and breeding success.
3. Marine mammals switch to photosynthesis, reducing dependence on prey fish and stabilizing populations despite overfishing.
4. Overfishing of prey fish increases coral cover because seabirds deliver fewer nutrients, which corals require for calcification.

Explanation: Overfishing key prey species like schooling fish limits food availability for higher trophic levels, such as seabirds and marine mammals, potentially reducing their reproduction and survival. This alters community structure through bottom-up effects in the food web. Populations of dependent species may decline, affecting biodiversity. Sustainable harvest must consider these linkages. Management can mitigate by setting limits based on ecosystem needs. This shows overfishing's ripple effects across trophics.