RISK OF EXTINCTION OF MARINE FISHESCHRISTINE HUNG

ERNEST TSUI

QUINCY LAM

OUTLINE

Causes of extinction risk

Endangered species assessment organizations

Major themes and ideas of the paper

Criteria for extinction

Management/Implementation

Critiques

WHAT IS EXTINCTION?

MAJOR CAUSES OF EXTINCTION: OVEREXPLOITATION Overfishing (Hutchings 2005)

By-catch (Polidoro et al. 2008)

Tourist industry (Taylor et al. 2014)

(IUCN 2008)

http://wwf.panda.org/what_we_do/endangered_species/cod/http://en.wikipedia.org/wiki/Parrotfish

MAJOR CAUSES OF EXTINCTION: HABITAT LOSS/DEGRADATION

Source:http://climate.nasa.gov/system/news_items/main_images/13_newsPage-13.jpg

Natural causes

Human-induced causes

Anthropogenic effects (Dulvy et al. 2003)

Example: Coral reefs faced with “Triple Jeopardy” (Olden et al. 2007)

MINOR THREATS OF EXTINCTION

Invasive species

Climate change

Pollution

Disease

(Dulvy et al. 2003)

LIFE HISTORY & VULNERABILITY Vulnerability to capture

versus vulnerability to overexploitation

Large body size

Small geographical range

Habitat specialization (Dulvy et al. 2003)

(Dulvy et al. 2003)

(Taylor et al. 2014)

COSEWIC – MARINE FISHES SPECIES SPECIALIST SUBCOMMITTEE (SSC)

Legislative mandate to assess risk of extinction status of marine fish species

Use 5 non-mutually exclusive groups of marine fish

1) Anadromous species

2) Elasmosbranchs

3) Species of high maximum age

4) Species of large maximum size

5) Species that have undergone substantial declines

(Powles 2011)

IUCN

(IUCN 2008)

41, 500 terrestrial plants and animals assessed, only 1, 500 marine species

6 major marine species groups assessed Sharks and rays Groupers Reef-building corals Seabirds Marine mammals Marine turtles

(Polidoro et al. 2008)

REYNOLDS ET AL. SUMMARY/REVIEW Current Status

Causes of declines and threatened status

Correlates of vulnerability

Relevance to extinction risk assessment

CURRENT STATUS                Only 6% of the world’s fish

have been examined

Logistically difficult to record and maintain detailed information on things that live underwater

Census of marine life project who oversaw some of the most recent biological explorations of the sea discovered around 6000 potential new species in 10 years 

(http://www.coml.org)

CURRENT STATUS

(Reynolds et al. 2005)

CAUSES OF CURRENT STATUS Documentation on species deemed threatened are often

lacking

Focus of assessments are biased

Focus is on groups of species that are considered a priori to be under the greatest threat

IUCN focusses on Elasmobranchs, groupers and wrasses

Most assessments occurred near shores

(Reynolds et al. 2005)

DECLINE STATISTICS As of 2001, marine fish has

declined an average of 65%, 29% of that by more than 80%

Estimates of more than 97% of biomass of large fishes (4-66kg) has been removed from the North Sea

(Reynolds et al. 2005)

CAUSE OF DECLINE AND THREATENED STATUS

Many disappearances were not noticed until long after they happened

Most extinctions have been detected retrospectively using indirect methods

Our best population census techniques often have little power (Dulvy et al. 2003)

Major cause of decline is exploitation

Efforts to reduce fishing has not been adequate

(Dinmore et al. 2003)

OVEREXPLOITATION & HABITAT LOSSOverexploitation Perceived as the main cause of declines

A biased viewpoint

Habitat Loss Restricted habitat = restricted population size

Habitat loss from human activities = large impact (Hawkins et al. 2000)

e.g. coral reefs

(Reynolds et al. 2005)

CORRELATES OF VULNERABILITY Dependent on interaction between extrinsic threats and

intrinsic ability of population to adapt to changes

Large bodied fish heavily fished(Jennings et al. 2001)

IMPORTANCE OF LIFE HISTORY

Life history

Growth rateNatural mortality ratesMaximum life spanAge at maturityReproductive output

(Charnov 1993)

LARGE-BODIED FISH

High fecundity

Repeated breeding

Large number of eggs

Reality of Large-Bodied Fish

Age at maturity and adult survival determines growth rate

Low growth rate at small population size

Much lower reproductive rate than expected

(Reynolds et al. 2005)

(Caswell 2001)

LIFE HISTORY

(Reynolds et al. 2005)

RELEVANCE TO EXTINCTION RISK ASSESSMENT

High Fecundity: a changing paradigm

High population fluctuation is not the norm

Current IUCN criteria inefficient (Dulvy et al. in press)

NEW SPECIES ASSESSMENT METHODS

New search parameters:

Body size + Geographic range (Dulvey & Reynolds 2002)

Fuzzy logic computation (Cheung et al. 2005)

New assessment parameters

Life history + IUCN criteria (COSEWIC)Life history dominant (AFS and CITES)

CATEGORIES OF EXTINCTION RISK Distinct Population Segment (DPS) and Evolutionarily

Significant Unit (ESU)

Vulnerable

Threatened

Endangered

Special Concern

Conservation Dependent

(Musick 2011)

(Musick 2011)

MAIN APPROACHES TO MEASURING EXTINCTION RISK

Life Histories and general trends

Time Series

Demographic analysis

(Dulvy et al. 2004)

GENERAL TRENDS Species have been found to have different responses to

extinction risks (Musick 2011)

Extinction risks vary between species groups and among different body sizes (Musick 2011)

Fecundity, water temperature, competition, and habitat vulnerability are some factors that may influence survival rates (Musick 2011)

BIOLOGICAL REFERENCE POINTS (BRP)

Reference points have been developed to find potential risks

Production Models (Dulvy et al. 2004)

Yield Per Recruit (Musick 2011;Dulvy et al. 2004)

Stock-Recruitment (Musick 2011)

Spawning Stock Biomass per recruitment (Musick 2011;Dulvy et al. 2004)

AFS RISK CRITERIA FOR DETERMINING SPECIES AT RISK

Identify DPS at risk at an early stage to avoid listing it as threatened or endangered

Reduce the probability of under or overestimating extinction

Use best existing knowledge of stock dynamics and apply them to low populations

Allow experts to discuss about life history and conservation status to reduce risk of extinction

(Musick 2011)

ADDITIONAL CONSIDERATION FOR EXTINCTION RISK MODELS

Geographical range that should be considered for a unit

Ecological specialization

Minimum viable population size

Comparability of threat criteria

(Dulvy et al. 2004)

EXAMPLE STUDY: CORAL REEFS

Carpenter et al. 2004`s paper “One-Third of Reef-Building Corals Face Elevated Extinction Risk from Climate Change and Local Impacts”

Coral Reef Background

Coral Reef Systems contributes to marine biodiversity Facing threats at a global and local scale

SPECIES SPECIFIC RISK 231 coral reef species were listed under threatened

categories in IUCN

40% of the 704 species are reef-restricted 303 of 704 species are highly susceptible to bleaching

Susceptible to general anthropogenic disturbances

(Carpenter et al. 2008)

GENERAL STATE OF CORAL REEF SYSTEM Eastern tropical pacific reef systems affected by warming

effects

Slow recovery in remote regions

1998 Indian Ocean mass bleaching affected coral reef systems and reducing structure

Cascading effect on fish populations

(Carpenter et al. 2008)

CORAL REEF MANAGEMENT AND IMPLICATIONS Possibility of going extinct,

depending on its ability to adapt to climate change (Carpenter et al. 2008)

Funding has been implemented to protect marine areas from overfishing, controlling tourism and coral reef damage but may not be effective in protecting coral reef systems (Goreau et al. 2001)

Need to address root causes of mortality in order for proper protection (Goreau et al. 2001)

Global Scale Management: Autonomous Reef Monitoring Structures (ARMS)

http://www.pifsc.noaa.gov/cred/survey_methods/arms/overview.php

MORE CRITIQUES COSEWIC (Polidoro 2011)

IUCN (Dulvy et al. 2004)

Problems with models? Makes too many assumptions (Dulvy et al. 2004)

Size-based effects on extinction risk may be irrelevant with life histories (Olden et al. 2007)

QUESTIONS?

DISCUSSION QUESTIONS1. Even if we gain a greater understanding of marine fish

species, will the ongoing effects of climate change affect our ability to conserve species at risk?

2. How should IUCN better refine their criteria for evaluating marine fish species at risk?

3. What alternatives, beside hatchery stocking, can be implemented towards managing threatened fish species?

4. With the cost and difficulty of conducting identification and stock assessment of fish species, should we continue the same practices, even though we currently don’t have an effective method of conserving threatened species?

5. Once a prominent commercial viable fish has gone extinct, will fisheries begin to decrease exploitation decrease?

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http://www.coml.org