global perspectives on fisheries bycatch: the legacy of lee … · bycatch or fishery interactions:...
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[email protected] Wakefield Bycatch Symposium
May 13, 2014
Global Perspectives on Fisheries Bycatch: The Legacy of Lee Alverson
Steve Murawski University of South Florida, St. Petersburg, FL 33701
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! What is Bycatch? (again….?) ! Some Evolving Global Perspec>ves/Percep>ons ! On Coun>ng/Accoun>ng for the (By)Catch ! Mi>ga>on Approaches
-‐ Regulatory-‐Based -‐ Incen>ves
! Economic & Social Considera>ons ! Ecological Considera>ons ! Bycatch as an Element of EBM/EAF Policies ! Comments on Our Conference
Outline
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! Any “non-‐target” catch ! Discards of Fish ! Dead Discards of Fish (MSA) ! Live & Dead Discards of Fish ! Dead Protected Resources (PETs) ! Any “Take” (alive or dead) of TEs (ESA) ! Total catch of a fishery minus landings of
managed species (Davies et al. 2009)
Defining Bycatch E>ology of the Word “Bycatch” is murky
but probably means “By-‐Product” Alterna>ve Working Defini>ons…
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Georges Bank
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monkfish yellowtail flounder
Spatial Distributions of Scallops and two Historical Bycatch
species
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Alverson, Freeburg et al. 1994 27 million tons / year based on 1980s and early 1990s data Reactions to the Report: • Call to action! • Does not have all the data • Need to get better data • Just 27%? • More study is required
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Follow-up Studies
• Kelleher 2005 (FAO, again), 8% Discard • Herrington et al. (USA) - 22% • NMFS (Karp, Desfosse, Brooke) (USA) 17% • Davies et al. 2009 40% (definition issue) • Lewiston, Crowder et al. PR “Hotspots” 2014 PNAS • An Update from NMFS (this meeting)
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Total Discards (million tons)0.0 0.5 1.0 1.5 2.0
Shrimp Trawl
Demersal Finfish Trawl
Tuna Longline
Midwater Trawl
Tuna Purse Seine
Multigear Multispecies
Mobile Trap Pot
Dredge
Sm. Pelagic Purse Seine
Gear Type
Kelleher (2005)
62.3% 9.6%
28.5% 3.4% 5.1%
1.4% 23.2% 28.3% 1.2%
Est. = 7.3 m tons 8% of total catch
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Why Did Bycatch rates Go Down? 27 million tons to 7 million tons
• Decreases in effort & changes in target species for some trawl fisheries
• Changes in regulations requiring greater
selectivity • Changes in regulations to use more of the
catch (aquaculture?)
or perhaps it was a change in methodology?
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Global Discard “Hotspots”
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Not everything that can be counted, counts….. Not everything that counts, can be counted……
On Counting Bycatch
often attributed to: A. Einstein
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An Hierarchy of Bycatch Importance
Does Bycatch: • threaten the existence of a species?, • materially contribute to overfishing (e.g., is
including bycatch critical to status determination – overfished, overfishing)?,
• contribute to “lost” yield potential?, • result in competitory interactions among
fisheries for common species? • result in “waste”? • create an ethics issue?
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Not Everything that Counts… Importance of Unobserved Mortalities
Mesh regulations have been used to reduce discards for a century………
Factors that may increase mortality: • Swimming exhaustion • Size/shape of mesh • Predation • Tow duration • Collision with ground gear
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Barotrauma in Recreational Fisheries Significant Technological Development to
Reduce Potential Mortalities
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Mitigation Approaches • Regulatory
- Time/Area management (if the fish cooperate) - Mandatory gear-based (compliance?)
• Incentives-based
- Relies on independent accounting - uses ingenuity “for doing good”
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Economic & Social Considerations • Fisheries are becoming much more
specialized and thus competition for bycatches becomes a limiting factor
• Rights-based fishing allows the market to assign the value of the limiting species (e.g., New England scallop vs. yellowtail flounder)
• Issues of equity, tenure and scale have confounded the use of rights-based systems
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Ecological Considerations
• Impacts of effort reduction in many global fisheries on catch and bycatches (potentially the most important factor in volume reduction)
• Change in gear types to reduce discards
can have profound and unintended consequences
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How Will Changes in Fishing Effort Affect Bycatch Species?
-70% change in shrimp effort Scavengers: Dolphins, birds, crabs, fish
-80% Reduction in USA Longline Effort
(swordfish & tunas) Effects on bycatch species
Sea turtles, bluefin tuna
Reduced shrimp effort means reduced finfish discards
yellowfin tuna catches
Effort Reductions
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Significant reduction in shrimp trawl effort likely a factor in increasing red snapper populations in the
Gulf of Mexico
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The Switch from Purse Seines to FADs in the Tropical Pacific
Some Consequences: • Reduced dolphin
deaths • Smaller average size of
tunas • Catch of a wide array of
small pelagic predators
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Advancing an Ecosystem Approach to Fisheries
Uses quantitative indicators and performance measures in management of target species and ecosystem
impacts
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Bycatch or Fishery Interactions: Bycatch and fishery interactions including mortalities of non-target species (e.g., multiple fisheries share the same species or status of non-target, non-commercial species) Indirect Effects of Harvesting: Indirect effects of harvesting through trophic interactions, and indirect effects through habitat-alteration, e.g. by fishing gear. Interactions between Biological and Physical Components of Ecosystems: Trends in environmental variables (e.g. temperature, other oceanographic attributes) may result in long-term re-structuring of ecosystems. Emphasis on low-frequency variability
Beyond SS, What are the Main Issues relevant to Ecosystem Approaches to Fisheries (EAF)?
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What is our National Policy Concerning Bycatches? National policy (such that it is) is embodied in various federal statutes (SFA, MMPA, ESA), but not clearly articulated Current NS-9 Language: “…minimize bycatch and to the extent bycatch cannot be avoided, minimize the mortality of such bycatch.”
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Policy Objective for bycatch mitigation might be: * Reduce deaths resulting from discards and unobserved mortalities to levels that do not threaten the attainment of biological objectives for target or non-target animals. * Bycatches from one fishery should not undermine the attainment of optimum yields in associated fisheries. The strange case of sea turtle management (managing the numerator = takes), a strong disincentive to rebuild populations
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Finishing the Job…… ! Clarify the Policy (-ies)
! Establish Objective Goals
! Provide the Tools * Require Minimum Standards for Data and Synthesis * Accelerate development of Gear/Management alternatives * Tap Creativity…
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What I Will be Looking For…. • Incen;vising Industry Crea;vity • Innova;on in Approaches • A Popula;on Context • Recrea;onal Fisheries • Priori;es Moving Forward
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Backup Slides
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What is Ecosystem-Based Management (EBM)?
Ecosystem-based management provides a comprehensive framework for living marine resource decision making. In contrast to individual species or single issue management, EBM considers a wider range of relevant ecological, environmental, and human factors bearing on societal choices regarding resource use.”……NOAA EGT
“Look at the whole picture, not just the parts.”
Dave Goethel SIMOR Listening Session
“Ecosystem-based ocean resource management is not well defined and we do not know how to implement it” UN Law of the Sea Meeting, April 2006
The #1 Myth Concerning EBM:
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Managing Bycatch is more than just fish
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= 1-8 = 9-25 = 26-63 = 64-145 = 146-309
Vessel Hours 2003 Satellite Tracking Data 1 hour resolution
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total
monk
cod
winter
flwitc
h ytfpla
icewind
owha
ddoc
kre
dfish
opou
tse
a rav
ensp
iny do
glitt
le sk
longh
orn
Dis
card
Rat
io (w
eigh
t)
0.0
0.2
0.4
0.6
0.8
1.0
New England Groundfish Otter Trawl -2002
34%
252 vessel trips
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Observing systems have helped us prosper
So have a great conference…..