General Outline What are fisheries? 1. Introduction Definition: - - PDF document

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General Outline What are fisheries? 1. Introduction Definition: - - PDF document

Nov 27, 2023 111 likes •189 views

General Outline What are fisheries? 1. Introduction Definition: an entity representing the harvest animals from aquatic environments 2. Fisheries Science Exploitation 3. Effects of Fishing Economics 4. Fisheries Biology

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SLIDE 1

General Outline

1. Introduction 2. Fisheries Science 3. Effects of Fishing 4. Fisheries Management

  • a. Politics
  • b. Economics
  • c. Societal Aspects

What are fisheries?

  • Definition: an entity representing the harvest

animals from aquatic environments

  • Exploitation

– Economics – Biology – Societal Aspects

  • Conservation
  • Politics
  • Regulation

Types of Fisheries:

  • Artisanal: traditional fishing effort involving

households; small-scale in economic input and effort; often associated with subsistence fishing, may be commercial in nature; usually local in effect.

  • Commericial: capitalization of catch with a larger-

scale economic input and effort; usually larger than household group.

  • Recreational: fishing for sport

How to catch a fish

  • Hooks

– Rod and reel – Longlines

  • Traps
  • Nets
  • Seines
  • Gill nets
  • Trawls
  • Etc.
  • Projectiles

– Spears – Harpoons

  • Alternative methods

– e.g. Dyn-o-mite

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SLIDE 2

History of Fishing

  • Earliest fishing implements – bone harpoons (90,000 yrs
  • ld) from Congo (2-m long catfish)
  • Artisanal fishing efforts – extinction of Stellar Sea Cows

(1768)

  • 1700-1900s: Whales, Seals, Otters, Turtles, Cod, Herring,

Haddock, etc.

  • Industrial Revolution and Technological Advancement

–Steam engine –Fleet development –Refrigeration –Transportation –Navigation

Fundamental Problems

  • Overcapitalization
  • Overfishing
  • Long-term damage to marine ecosystems
  • Extinction

Tragedy of the commons

  • Garret Hardin, Science (1968)
  • Scramble competition: when

many share a resource, the resource is at strong risk to get depleted (= species goes extinct) because the economical strategy is to get more than the others (=maximize gain).

  • We see this problem in hunting/

fishing but also on grazing on public land.

Biological theory of exploitation N=population size K=Carrying capacity change of N per time t population growth rate Yield (Surplus of population)

  • The logistic growth function can be

solved for Y and so we can get the surplus for known K and r.

Fisheries Science

  • Roots in Population

Ecology

  • Applied ecological

research that provides information for management structures

  • Empirical Work
  • Modeling

– Stock Assessments – Compensation/Depensation – Allee Effect

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SLIDE 3

Evolution of models reflects the evolution of our understanding of these systems

  • Maximum Sustainable Yield (MSY): Maximum use that a renewable

resource can sustain without impairing its renewability through natural growth or replenishment

  • Total Allowable Catch (TAC): Amount of catch managers allow to be

taken

  • 1970s and early: logistic growth model, deterministic, no

environmental or stochastic variation

  • 1980s: depensation – low survival at low density, stochasticity in

early life history, maximize MSY

  • 1990s: precautionary – use MSY as limit
  • 2000s: ecological considerations

EBM

  • length–age
  • weight–length
  • fecundity–length
  • maturity–age
  • spawner–recruit
  • selectivity–age
  • stochasticity
  • species interactions
  • environmental interactions

The Models: Summarized

Classical Neo-Classical Modern Ecosystem-Based Approaches Hmmmm…

  • length–age
  • weight–length
  • fecundity–length
  • maturity–age
  • spawner–recruit
  • selectivity–age

Fisheries Impact: Oops…forgot about all that pesky Biology

“I believe that the cod fishery, the herring fishery, the pilchard fishery, the mackerel fishery, and probably all the great sea-fisheries are inexhaustible; that is to say, nothing we can do seriously affects the number of fish (Thomas Huxley 1883)”

Peruvian Anchovy Fishery

Status of Fisheries Impact: Oops…forgot about all that pesky Biology

  • Extinctions due to overfishing
  • Numerical
  • Ecological
  • By-Catch – catch of non-target species (generally discarded)
  • Economic Collapse
  • Habitat Degradation
  • Reduced Ecosystem stability

“I believe that the cod fishery, the herring fishery, the pilchard fishery, the mackerel fishery, and probably all the great sea-fisheries are inexhaustible; that is to say, nothing we can do seriously affects the number of fish (Thomas Huxley 1883)”

Global Marine Fisheries Trends

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SLIDE 4

U – underexploited D – moderately exploited M – fully exploited S – overfished R – recovering

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SLIDE 5

Why did this happen?

  • Inaccurate estimates of population sizes

– Models descriptive, not predictive

  • Parameters inaccurate (e.g. Catch-per-unit-effort (CPUE))

– Biology of species can drastically affect the assumptions of these models – Use of destructive fishing practices – Ignorance of ecosystem affects

  • Inappropriate economic incentives
  • Lack of political/social will

Fishing Down the Food Web

Food Web 2 2.3 2.3 3.1 3.8 Reductions of Top-Level Predators Example: New England Groundfish and Lobsters

2004 Catch: $253.5 million 62 million lbs.

Age distributions and reproduction

photo from www.daisymaefishing.com

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SLIDE 6

Life History Strategies: Age-structured schedules of mortality and reproduction

  • Long-lived: late age at first reproductive

maturity

  • Aggregation
  • Low intrinisic rate of increase – offspring

number

  • Differential reproductive value to older

individuals

  • Strong association with specific habitat

Example: Rockfish Larval Abundances

Example: Red Hinds and Nassau Groupers in Bermuda

The Economic Issues

  • Scramble Competition (Tragedy of the

Commons)

– No advantage to helping your neighbor – No advantage to saving for later

  • Unlimited access
  • Growing demand on limited resources
  • Subsidies that stimulate overcapacity
  • Ignorance about impact
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SLIDE 7

Despite improvements in science, lag in action and lack of Closed management cycle causes problems

Modern approaches: Access

  • Traditonal tools:

– Gear restrictions – Regulation of Catch and effort

  • Access structure (limited entry into the race-to-

fish):

– Limited entry

  • Regulate number of licenses
  • Marine Protected Areas (MPAs)

– Individual quotas (IQs)

  • Transferable (ITQs)
  • Vessel (IVQs)

Modern approaches: Decision Making

  • “Minister of Fisheries” (United Kingdom)

– Ultimate authority lies with the minister

  • Council (USA)

– Appointed individuals from various sectors; try to build consensus but ruled by majority vote

  • Commission (international)

– Representatives from membership councils

  • All entities beginning to adhere to precautionary

axioms (risk management)

Modern approaches: Spatial Scales

  • Unit Stock

– Fisheries can be defined into discrete independent units – Not biological or economically accurate – Evolutionary Significant Unit (ESU):

  • (1) Substantially reproductively isolated from other conspecific

population units

  • (2) Represent an important component in the evolutionary legacy of a

species

  • Metapopulations

– population consists of interacting sub-populations – extinction/colonization – source-sink dynamics