RISK OF EXTINCTION OF MARINE FISHES

SPRING 2015

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 speciesUse 5 non-mutually exclusive groups of marine fish

1) Anadromous species2) Elasmosbranchs3) Species of high maximum age4) Species of large maximum size5) 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 rate❑ Natural mortality rates❑Maximum life span❑ Age at maturity❑ Reproductive 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?

LITERATURE CITED

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http://www.coml.org