Aquaculture and Fishing Practices Quiz

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Questions and Answers

What percentage of world fish production was attributed to aquaculture in 2020?

40%

50% (correct)

60%

25%

Which of the following is a consequence of inappropriate fishing methods?

Enhanced biodiversity

Increased fish populations

Habitat destruction (correct)

Growth of aquaculture

What type of fishing targets species that live near the seabed?

Commercial fishing

Pelagic fishing

Demersal fishing (correct)

Drift fishing

Which seabird species has benefited from bycatch according to the content?

Northern Gannet Signup and view all the answers

Which fishing method involves the use of traps?

Passive fishing Signup and view all the answers

What characterizes pelagic fisheries?

Focus on species in the water column Signup and view all the answers

What was the breeding range situation of the Northern Fulmar until the late 19th century?

Only one breeding colony in the British Isles Signup and view all the answers

Why is bycatch difficult to avoid in commercial fishing?

Targeting specific species is challenging Signup and view all the answers

What is the primary reason sea fisheries and aquaculture are important globally?

They supply food, nutrition, and employment. Signup and view all the answers

Which of the following species is NOT mentioned as a commonly landed pelagic species?

Bluefin Tuna Signup and view all the answers

Where are the most productive fishing areas typically found?

Over continental shelves and regions of upwelling. Signup and view all the answers

What impact has advanced technology had on fishing practices?

It allows fishing in previously unreachable areas. Signup and view all the answers

How do modern fishing methods differ from traditional methods?

Modern methods rely more on technology and equipment. Signup and view all the answers

What role does bycatch play in modern fishing practices?

It includes species like Frilled Sharks that are caught unintentionally. Signup and view all the answers

In what way is fishing seen as a less complex method of food acquisition compared to farming?

Fishing relies on natural populations rather than cultivated ones. Signup and view all the answers

Which factor does NOT significantly contribute to fish biomass in productive areas?

Technology used in fishing. Signup and view all the answers

At what size do fish begin to be commonly caught in trawl nets?

25 cm Signup and view all the answers

What is the length a cod typically reaches maturity?

50 cm Signup and view all the answers

Which characteristic is NOT associated with the European plaice?

Long-distance swimmer Signup and view all the answers

Where are plaice commonly found in the North Sea?

Sandy bottoms in shallow waters Signup and view all the answers

What time of year is the quality of plaice typically poor?

Spawning time Signup and view all the answers

What is the primary method used to catch plaice?

Trawl or seine fishing Signup and view all the answers

In which areas does spawning occur for plaice?

Southern North Sea and Irish Sea Signup and view all the answers

During which months does spawning primarily occur for plaice?

January and March Signup and view all the answers

What is the primary dependence of the larva immediately after hatching?

Using a yolk-sac for nutrition Signup and view all the answers

At what size does the cod typically reach by the end of the first 6 months in the North Sea?

8 cm Signup and view all the answers

During the planktonic phase, which organisms are the main food for young cod?

Nauplius larvae of copepods Signup and view all the answers

What physical change occurs in young fish when transitioning from a planktonic to a demersal lifestyle?

Change in body coloration and pattern Signup and view all the answers

What is a significant prey for adult cod while hunting?

Squid Signup and view all the answers

What happens to the young cod when they reach the end of their planktonic phase?

They disappear from surface layers and go to the seabed Signup and view all the answers

How does the growth rate of cod differ in various geographical locations?

Growth is slower further north Signup and view all the answers

What are cod fry often preyed upon by during their early stages?

Carnivorous zooplankton such as ctenophores Signup and view all the answers

What primarily affects the timing of fish migrations in the discussed regions?

Shifts in major currents Signup and view all the answers

What type of environment do overwintering fish primarily inhabit?

Near the seabed Signup and view all the answers

During which part of their migration do fish begin to form surface shoals?

At the end of winter Signup and view all the answers

What food sources are working as the primary diet for overwintering fish?

Small crustaceans and polychaetes Signup and view all the answers

Following spawning, where do fish that spawned in the Celtic Sea typically migrate?

Eastwards towards the English and French coasts Signup and view all the answers

What is the primary movement pattern of fish that overwintered in the Irish Sea at the start of spring?

South-westwards Signup and view all the answers

Where do fish that spawn in the central North Sea primarily return to post-spawning?

The Norwegian coast Signup and view all the answers

What role do cascade currents play in the local ecosystem for overwintering fish?

They carry food down from the surface. Signup and view all the answers

What does the equation $S2 = S1 + (A + G) - (C + M)$ represent?

The beginning and ending weights of stock and changes due to recruitment and growth Signup and view all the answers

In what situation is a fishery considered 'stabilized'?

When the total stock weight remains unchanged Signup and view all the answers

What is the biological optimum fishing rate?

The fishing rate that maximizes sustained landings of fish Signup and view all the answers

Which of the following factors is NOT considered when determining the optimum yield?

The environmental impact of fishing gear Signup and view all the answers

What happens during overfishing, according to the passage?

The fish stock experiences low natural yields Signup and view all the answers

Which statement best reflects the relationship between fishing, stock, yields, and profitability?

Different catch compositions affect stock and yield differently Signup and view all the answers

What does the term 'natural yield' refer to?

The increase in stock weight from recruitment and growth without fishing Signup and view all the answers

Why is it necessary to regulate fishing activity?

To maintain stable fish populations and sustainable yields Signup and view all the answers

Which factor has contributed to the impressive expansion of fulmars in the 20th century?

Availability of fishing vessel discards Signup and view all the answers

What is indicated as a likely cause for the decline in the number of breeding pairs of fulmars since the 21st century?

Changes in fishing regulations Signup and view all the answers

What type of fishing vessel is described as capable of processing its catch on board and freezing it?

Supertrawlers Signup and view all the answers

Which of the following best describes the current understanding of fulmar diets?

Varies considerably by geographic region Signup and view all the answers

Which fishing methods are mentioned as contributing factors to the population changes in fulmars?

Trawling and longline fisheries Signup and view all the answers

What is implied about the relationship between fishing activities and bird populations like the fulmar?

Changes in fishing lead to significant shifts in unrelated species Signup and view all the answers

How is the size of industrial fishing vessels characterized in the passage?

Can exceed 140 meters and carry large catches Signup and view all the answers

What factor in the North Sea is mentioned as changing due to climate change, affecting the fulmar's food sources?

Decline of sand eels and zooplankton Signup and view all the answers

What is a significant consequence of overfishing?

Reduction in fish stocks Signup and view all the answers

Why are lower limits imposed on the size of fish that can be caught?

To allow immature fish to reproduce Signup and view all the answers

How did advancements in technology impact fishing practices after Huxley's statement in 1883?

Enabled more effective fishing methods Signup and view all the answers

What was E.S. Russell’s conclusion about the state of fisheries in northwest European waters?

Overfishing was evident in many trawl fisheries Signup and view all the answers

What did Huxley mistakenly believe about the fisheries he addressed?

Fishermen's impact was negligible Signup and view all the answers

What has been observed in areas of intensive fishing in the northeast Atlantic since Huxley’s prediction?

A reduction in stocks of favored species Signup and view all the answers

What does overfishing primarily result from?

Catching too many immature fish Signup and view all the answers

Which of the following is NOT a reason that traditional fishing methods became less common?

Regulatory changes in fishing practices Signup and view all the answers

What type of fish primarily becomes sexually mature during their fourth year?

Southern North Sea herring Signup and view all the answers

Which environmental condition contributes to a rich plankton supply for fish?

Warm, sunny summer Signup and view all the answers

Which of the following species is an example of anadromous fish?

Atlantic Salmon Signup and view all the answers

What characterizes catadromous fish species?

They spend their adult life in freshwater and migrate to spawn in the ocean. Signup and view all the answers

What happens to many Pacific Sockeye Salmon after spawning?

They die after spawning. Signup and view all the answers

What is a primary factor that affects the fat content of fish flesh?

The type of plankton consumed Signup and view all the answers

How do young Atlantic Salmon behave before migrating to the ocean?

They live in freshwater for up to 3 years. Signup and view all the answers

What physiological adaptation is critical for fish that migrate between freshwater and ocean environments?

Ability to adapt to salinity changes Signup and view all the answers

What has been the impact of bottom trawling on Atlantic cod populations?

It has caused changes in the ecosystem, hindering recovery. Signup and view all the answers

How much did the world catch of Atlantic cod reach in 2018?

1.2 million tonnes Signup and view all the answers

What is the typical depth at which Atlantic cod are predominantly found?

Between 150 to 200 meters Signup and view all the answers

What percentage of Atlantic cod stocks is currently reported to be in a poor state?

10% Signup and view all the answers

Which of the following regions is NOT mentioned as a part of the Atlantic cod's distribution?

South China Sea Signup and view all the answers

What has been a major technological change in fishing since the late 1940s?

Development of synthetic fishing nets Signup and view all the answers

What caused the initial perception that Atlantic cod could not be overfished?

The species' historical abundance. Signup and view all the answers

What is indicated by the current status of Atlantic cod fisheries as rated by the Marine Conservation Society?

Five out of 31 fisheries are highly sustainable. Signup and view all the answers

What has caused the saturation of fish catches at a particular level since around 1970?

Overfishing and environmental impacts Signup and view all the answers

In what temperature range is Atlantic cod most abundant?

0°C to 10°C Signup and view all the answers

How has the transition from steam to diesel power affected fishing vessels?

Improved power and speed Signup and view all the answers

What is a consequence of fishing occurring too early in the fishes’ life cycle?

Destruction of undersized fish Signup and view all the answers

What role do modern navigation systems like GPS play in fishing practices?

Allowing precise returns to productive fishing areas Signup and view all the answers

What has been the average annual increase in world landings of fish from 1948 to 1968?

7% Signup and view all the answers

What is indicated by the flattening of the catch curve despite increased fishing efforts?

Saturation of fish populations and overfishing issues Signup and view all the answers

What is the impact of fishing vessels equipped with refrigeration systems?

They allow boats to fish for extended periods without spoilage. Signup and view all the answers

What is a significant factor in the slow recovery of Atlantic Cod stocks?

The lack of older female cod for reproduction Signup and view all the answers

How did war affect the fish stocks in the northeast Atlantic during the 20th century?

Fish stocks recovered due to reduced fishing activity Signup and view all the answers

What type of fishing approach is increasingly being understood as necessary for fisheries management?

Considering the entire ecosystem Signup and view all the answers

What has been the state of cod stocks in relation to their population size since the 1960s?

Stocks are around 10% of their 1960s population Signup and view all the answers

What ecological impact does seabed trawling have on cod populations?

It destroys bottom habitats relied upon by cod Signup and view all the answers

Which of the following best explains the concept of 'motherfish' in relation to cod recovery?

Larger females that produce more eggs Signup and view all the answers

What does the significant decline in haddock landings during the 1930s illustrate about fisheries?

Fishing yields can be temporarily increased after periods of underfishing Signup and view all the answers

What evolutionary pressure may result from constant heavy fishing on cod populations?

Fish to mature earlier at smaller sizes Signup and view all the answers

Study Notes

Human Impacts on Sea Fisheries and Aquaculture

Sea fisheries and aquaculture are significant topics, encompassing various books and scientific papers. Fishing is essential to feeding the global population, providing nourishment, employment, and income.
Fisheries and aquaculture play crucial roles in global food and nutrition needs.
Advanced technology now allows fishing almost anywhere and at greater depths than previously possible, leading to increased species variety in catches. This is evident in fish markets—with more unusual species being targeted.
Bycatch, including species like Frilled Sharks, is a result of fishing methods targeting different species (and also invertebrates and marine mammals).
Key pelagic species, such as Peruvian Anchovy, Alaskan Pollock, Chilean Jack Mackerel, Atlantic Herring, and Chub Mackerel, account for a substantial portion of global landings (around 15%).
Productive fishing areas are typically located over continental shelves and upwelling zones due to higher primary production levels and subsequently higher fish biomass.
Inappropriate fishing methods and overfishing threaten entire ecosystems through habitat destruction and removal of keystone species.
Efficient fisheries need to avoid bycatch; sometimes offal and bycatch can indirectly benefit other marine species.
Northern Gannets (Morus bassanus) populations have increased in some areas due to scavenging bycatch.

Reproductive Strategies and Life Cycles

Fishing management requires an understanding of a species' life history and reproductive strategies. Two main strategies, r- and K-strategists, exist.
R-strategists produce large numbers of offspring, with little effort in supporting offspring survival, while K-strategists ensure few, but well-supported offspring.
Different environments will cause species to have unique life histories.
Many ray-finned fish (Actinopterygii) lay large numbers of small eggs, broadcast into the water and externally fertilized, illustrating an r-strategy.
Some examples of r-strategists that contribute significantly to global fish landings are those mentioned above as key pelagic species.
Other species display K-strategists strategies—with examples like sharks, rays, and chimaeras which produce fewer young but invest more resources in their offspring's survival.

Fisheries Components and Issues

Fisheries are divided into demersal (bottom-dwelling) and pelagic (water-column).
Demersal fisheries target species like cod, flatfish, rays, and Orange Roughy.
Pelagic fisheries target shoals like herring.
Inappropriate fishing methods, including overfishing, threaten entire ecosystems through habitat destruction and removal of keystone species.
Efficient fisheries need to avoid bycatch; sometimes discards and bycatch can indirectly benefit other marine species.
Northern Gannets (Morus bassanus) populations have increased in some areas due to scavenging bycatch.

Fulmars

Northern Fulmars (Fulmarus glacialis) demonstrate a close connection between fishing activities and non-target species.
Historically, their populations were limited, but expanded notably during the 20th century due likely to a food source coming from fisheries discards.
Recent declines may be linked to reduced discards and other regulatory changes.

Example Fish Life Histories

Atlantic cod (Gadus morhua) is important, historically abundant, but now overfished in many areas.
Cod life history involves migration between spawning and feeding grounds, with a long lifespan and slow growth.
Cod primarily feed on smaller organisms near the seabed.

European Plaice (Pleuronectes platessa)

It is important commercially and demonstrates a typical life history.
Plaice (Fig. 8.2, page 396) spawn in the North Sea, English Channel, and Irish Sea during the winter months, with juveniles commonly found in shallow, coastal nursery areas.

Atlantic Herring (Clupea harengus)

Herring are pelagic and migrate for spawning, feeding, and migration, showing remarkable movements and migrations based on their lifespan.
Herring feed primarily on plankton in the open ocean, particularly during the spawning process.

Anadromous and Catadromous Species

Salmon (Salmonidae), shads, and some lampreys (Petromyzontidae) are anadromous migrating from ocean to freshwater to spawn.
Freshwater eels (Anguilla spp.) are catadromous.

Stock Assessment Methods

Stock assessment aims to evaluate ongoing fishery implications for a stock, for example, to identify overfished stocks, and to estimate sustainable fishing rates.

Overfishing

Overfishing depletes fish populations, hindering restocking rates.
The effects of overfishing include dramatic population declines, like those seen in Cod.
Often, overfishing coincides with other environmental concerns such as climate change.

Fishery Management and Regulations

Fishery management often involves setting quotas, establishing protected areas or restricted time frames for fishing (closed season).
Implementing rational fishing methods is necessary to avoid overfishing and negative ecosystem consequences.
Overfishing dramatically impacts fish populations and can cause ecosystem collapse, as demonstrated in the Grand Banks cod fishery collapse.

Aquaculture

Aquaculture is becoming a vital protein source, particularly for high-value species like salmon and sturgeon.
Aquaculture methods vary widely, from simple pond culture of herbivorous fish to more sophisticated systems like tanks or cages (sea-cage farming).
Aquaculture faces challenges, such as pollution from waste products, escapes of farmed fish into wild populations, which can compromise local wild fish genetic lines.
Aquaculture also relies on feeding the fish for optimal growth; this can present challenges for sustainability.
Seaweed farming makes use of natural processes and can serve as an alternative to traditional fish farming regarding certain sustainability claims.
Stocks used for aquaculture feed often rely on wild-caught fish and crustaceans
In many cases, Aquaculture production exceeds Wild capture fisheries
Aquaculture developments in some regions are more sustainable than others

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Test your knowledge about aquaculture and fishing practices in this quiz. Explore key concepts such as bycatch, fishing methods, and the ecological impact of fishing technologies. Perfect for students studying marine biology or environmental science.