Fishing Gear and Destructive Methods

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Questions and Answers

Which type of fishing gear is considered most destructive due to its impact on ecosystems?

Gill nets

Purse seines

Fishing with hooks

Bottom trawler (correct)

What differentiates active fishing from passive fishing methods?

Active fishing uses hooks and lines exclusively.

Active fishing relies solely on baited traps.

Active fishing involves moving gear across the seafloor. (correct)

Active fishing is limited to deep-sea fishing.

What is the primary purpose of Fish Aggregating Devices (FADs)?

To attract fish to a specific area. (correct)

To keep fish off the seafloor.

To ensnare fish in sediment.

To trap fish using nets.

Which of the following fishing methods is primarily associated with the aquarium trade?

Cyanide fishing Signup and view all the answers

Which fishing gear is described as focusing on invertebrates and causing high disturbance to the seafloor?

Dredges Signup and view all the answers

What occurs when the catch increases while effort remains the same or decreases?

CPUE increases Signup and view all the answers

Which of the following is NOT a method to measure mortality in fisheries?

Length to weight conversion Signup and view all the answers

In the context of biological growth characteristics, which measurement is preferred because it is easier to measure?

Length Signup and view all the answers

What equation represents the total mortality (Z) in fisheries?

Z = M + F Signup and view all the answers

Which of the following statements is accurate regarding overfishing and its impact on biomass?

Overfished stock occurs when B < Bmsy Signup and view all the answers

What was a limitation of the first attempt by Sea Around Us in categorizing fishing gear?

It resulted in errors at country levels. Signup and view all the answers

What are two essential aspects to understand sustainability in fisheries?

Condition of stock and effects of fishing stock. Signup and view all the answers

Which of the following is NOT a step in the ideal process of stock assessment?

Collect market data for fish pricing. Signup and view all the answers

What complicates the determination of a self-contained breeding population in unit stock?

The dispersive plankton larval stage can move long distances. Signup and view all the answers

Which method is NOT mentioned for collecting catch data?

Mobile phone surveys. Signup and view all the answers

What is one reason why data collection adds uncertainty and bias in fisheries assessments?

Different fishers use different methods. Signup and view all the answers

How is fishing effort typically measured?

By fleet or gear type used. Signup and view all the answers

Why might political boundaries affect stock assessment?

They are often different from biological stock boundaries. Signup and view all the answers

Which method is NOT mentioned as a choice for surveying species diversity?

Trophic level analysis Signup and view all the answers

What is one way to minimize impacts on fish during construction?

Use bubble curtains to reduce noise emissions Signup and view all the answers

What is a major issue targeted pelagic sharks face?

High levels of illegal fishing Signup and view all the answers

What percentage increase has global fish consumption seen since 1990?

122% Signup and view all the answers

Which type of sharks spends most of their time in coastal environments?

Coastal sharks Signup and view all the answers

Which indicates a significant conservation challenge related to shark fishing?

Inadequate handling of caught sharks by fishermen Signup and view all the answers

How many million sharks are removed from the ocean each year due to fisheries?

100 million Signup and view all the answers

What is one of the conservation initiatives mentioned?

Save our seas Signup and view all the answers

Which of the following nutrients are classified as macronutrients?

Lipids Signup and view all the answers

What is one of the responsibilities of DPIRD concerning fisheries?

Monitoring all bony fish and sharks Signup and view all the answers

Why is Western Australia considered to have low productivity in fishing?

Less river attachment and nutrients Signup and view all the answers

What is a suggested indicator for maximum sustainable yield?

Maximum nutrient yield Signup and view all the answers

What economic impact does recreational fishing have in Western Australia?

$2 billion in expenditure Signup and view all the answers

How often is stock assessment carried out on fisheries?

Every 3 years Signup and view all the answers

Which of the following seafood species is NOT mentioned as a part of commercial fisheries in WA?

Barramundi Signup and view all the answers

What is one of the key issues facing fisheries in the future?

Declining fish populations Signup and view all the answers

Which aquatic species are commonly highlighted in recreational fishing in WA?

Blue swimmer crabs and pink snapper Signup and view all the answers

What role does education play in changing fisheries management?

It influences public support for management policies Signup and view all the answers

Study Notes

Fishing Gear

Fishing gear can be categorized by activity level, catch method, and a variety of other factors.
Passive gear includes traps, pots, weirs, and gillnets.
Active gear includes bottom trawls, midwater trawls, dredges, purse seines, and FADs.
Bottom trawls are further categorized into otter trawls (faster moving) and beam trawls (slower moving).
Midwater trawls are designed to avoid contact with the seafloor.
Dredges are heavy gear targeting invertebrates and causing significant seafloor disturbance.
Purse seines are used to encircle fish schools, primarily pelagic species but also beach purse seines.
FADs (Fish Aggregating Devices) are surface rafts that attract fish, both moored and drifting.

Destructive Fishing

Dynamite fishing, although illegal, is a highly destructive method.
Cyanide fishing, primarily used in the aquarium trade, is also highly destructive due to its toxicity.
Bottom trawling is considered the most destructive fishing gear globally.

Sustainable Fisheries

Sustainable fisheries aim to maintain fish stocks at specific levels over time.
Understanding the condition of fish stocks (biomass) and the effects of fishing on stocks is essential.

Stock Assessment

Stock assessment aims to determine the status of fish populations.
The process involves defining the unit stock, collecting catch data, collecting effort data, calculating catch per unit of effort (CPUE), and collecting biological characteristics data.
Biological characteristics data includes growth, mortality, stock size, and recruitment.
The Von Bertalanffy Growth Function is used to model fish growth.

Fishing Effort

Fishing effort can be measured in various ways, including the number of boats, the duration of fishing, and the type of gear used.
Normal effort refers to the number of boats in a fishery, while effective effort considers the hours or days fished per year per boat.

Catch Per Unit of Effort (CPUE)

CPUE reflects changes in relative fish abundance over time.
A stable CPUE indicates that catch changes at the same rate as effort.
An increasing CPUE indicates increasing catch with constant or decreasing effort.
A decreasing CPUE indicates decreasing catch with increasing effort.

Mortality

There are three types of mortality in fisheries: total mortality (Z), natural mortality (M), and fishing mortality (F).
Z = M + F

Stock Size

Estimates of fish stock size can be obtained through surveys or by using an index of stock density.

Stock Recruitment

Stock recruitment models, such as Beverton and Holt, Ricker, and Shepherd, are used to assess the relationship between fish abundance and recruitment.
Stock recruitment data is often highly variable.

Surplus Production

Surplus production refers to the difference between the biomass produced in a given year and the biomass consumed by natural mortality, fishing, and other factors.
Overfished stocks have biomass below their maximum production potential.
Overfishing occurs when fishing mortality exceeds the sustainable level.

Minimizing Impacts

Minimizing impacts of fishing activities on marine ecosystems includes reducing noise pollution, burying cables, minimizing construction activities during spawning season, minimizing impacts on target species, improving communication with fishers, and providing alternative work opportunities.

The Status of Seychelles Sharks

Pelagic sharks are often migratory and have large home ranges.
Coastal sharks are typically found in inshore environments and have smaller home ranges.
Both pelagic and coastal sharks are facing significant threats from overfishing and bycatch.

Shark Fishing

Global shark populations have declined by 70% due to overfishing.
Shark finning, often conducted illegally, targets pelagic species for their fins.

Seychelles Fishing

Seychelles fishing includes artisanal (incidental) fishing, commercial (bycatch) fishing, and illegal, unreported, and unregulated (IUU) fishing.
Only two vessels currently target sharks commercially.

Conservation and Research Initiatives

Conservation and research initiatives in Seychelles include Save Our Seas and Seychelles Seatizens.

Marine Monitoring

Marine monitoring methods include BRUVS (Baited Remote Underwater Video Systems), eDNA, passive acoustic monitoring, PBRUVs (Pelagic Baited Remote Underwater Video), targeted diver surveys, and incidental sightings.

Catching Nutrients

Malnutrition affects 1 in 3 people globally.
Fish is a significant source of essential nutrients, including macronutrients (carbohydrates, protein, lipids/fats) and micronutrients (vitamins, minerals, phytochemicals).

Blue Food Concept

The blue food concept recognizes the importance of seafood as a food source, particularly for low-income countries.

Environmental Impacts of Animal Foods

The environmental impacts of animal production, including aquaculture, are significant.

Species Nutrient Variability

Species from tropical regions have higher concentrations of calcium, iron, and zinc.
Species from cold regions have higher concentrations of omega-3 fatty acids.
Smaller species generally have higher concentrations of calcium and iron.

Maximum Nutrient Yield

Maximum nutrient yield has been proposed as an indicator for maximum sustainable yield.

**DPIRD (Department of Primary Industries and Regional Development, Western Australia)

DPIRD manages fisheries for all bony fish, sharks, aquatic invertebrates, marine algae, and seagrass in Western Australia.
Tuna and billfish are managed internationally.

Western Australia Fisheries

Western Australia has a large coastline and inland water environment, ranging from tropical to temperate waters.
It faces challenges due to low productivity, being less reliant on river attachments for nutrient input.
Western Australia's fisheries are managed sustainably across commercial, aquaculture, and recreational sectors.

Commercial Fisheries in Western Australia

There are 50 commercial fisheries in Western Australia.
Key species include Western Rock lobster, prawns, scallops, abalone, Australian sardines, scaly mackerel, Goldband and pink snapper, Spanish mackerel, and Australian salmon.
Fishing licenses provide access rights, not property rights.

Recreational Fisheries in Western Australia

Recreational fishing is popular, with over ¼ of the population participating.
Key species include blue swimmer crabs, Western Rock lobster, school whiting, herring, pink snapper, dhufish, squid, black bream, and silver trevally.

Aquaculture in Western Australia

Aquaculture is a growing sector, with species including barramundi, mussels, oysters, abalone, marron, and trout.

Fisheries Management in Western Australia

Commercial fisheries are managed under formal management plans.
Recreational fisheries are managed through regulations.
10 fisheries hold MSC (Marine Stewardship Council) accreditations.
Management strategies involve stock assessment, harvest strategies, fisheries-dependent and independent data.

Stock Assessment in Western Australia

Stock assessments are conducted every three years.
The 2021 assessment indicated that further management action is required for full recovery by 2023.
The current management has halted the decline, but further recovery is needed.

Managing Fisheries Into the Future

Challenges for fisheries management moving forward include population growth, coastal development, technological shifts, climate change, certification through WTO (World Trade Organization) and MSC, loss of access through marine parks, and maintaining a strong social license.

Aquaculture Reporting

A key issue in aquaculture is the lack of comprehensive reporting on the fish used to feed farmed fish.

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Description

Explore the various types of fishing gear used in different fishing activities, including both passive and active methods. Additionally, learn about the impact of destructive fishing practices such as dynamite and cyanide fishing. Test your knowledge on this crucial aspect of marine life sustainability.