Marine fisheries: is the glass half full or half empty?
Boris Worm Dalhousie University, Halifax, Nova Scotia, Canada Voyage of the Beagle 1831-36 St. Paul’s Rocks
The smallest rock […] supports likewise a large number of fish. The sharks and the seamen in the boats maintained a constant struggle which should secure the greater share of the prey caught by the fishing-lines. Since Darwin: >99% loss of oceanic whitetip sharks
Source: Baum & Myers (2004) Ecol. Lett. 7:135–145 Keeling (Cocos) Island
There is to my mind much grandeur in the view of the outer shores of these lagoon islands. […] It is excusable to grow enthusiastic over the infinite number of organic beings with which the sea of the tropics teems. Since Darwin: Coral reef degradation
Source: Pandolfi et al. (2005) Science 307:1725-1726
Part I: Half-empty Loss of coastal biodiversity
7% extinct
36% collapsed
Source: Worm et al. 2006. Science 314:787-790 Loss of diversity
Source: Worm et al. 2006. Science 314:787-790 Loss of services
Source: Worm et al. 2006. Science 314:787-790 Increased risks
Source: Worm et al. 2006. Science 314:787-790 Oyster example
• Removal of Oysters • Algal blooms 1960s
Source: Worm et al. 2005. Science 309:1365-1369
1970s
Source: Worm et al. 2005. Science 309:1365-1369
1980s
Source: Worm et al. 2005. Science 309:1365-1369
1990s
50% decline
25% decline 50% decline
Source: Worm et al. 2005. Science 309:1365-1369
Burning through our natural capital
0
A r=0.96 10 P<0.0001
20
30 29% collapsed 40
50 B Collapsed taxa (%) taxa Collapsed 60 r=0.96 70 P<0.0001
80 1950 1960 1970 1980 1990 2000 Year
80 Source: Worm et al. 2006. Science 314:787-790 Declining global seafood supply
Sources: Watson & Pauly (2001) Nature 414:534 – 536, U.S. Bureau of the Census, International data base
Ecosystem changes
• Loss of large fish • Fisheries shift to lower levels • Diversity decreases • Ecosystems become - less resilient - less predictable - less productive
Source: Pauly & MacLean 2003, Island Press Half-empty? • Large declines in marine biodiversity • 25-35% of fisheries collapsed • Wild catches of food fish declining • Other services declining even faster • Marine species increasingly listed as threatened and endangered
Source: Time magazine, Nov. 2006 Part II: Half-full Most large fisheries still producing
60 52
50
40
30 20
20 17 Percent Percent of fisheries 10 7 3 1 0
Source: FAO (2007) The State of World Fisheries and Aquaculture 2006 http://www.fao.org Rebuilding efforts pay off
200000
180000 200-Mile Emergency 160000 Limit Closure 140000
120000 Biomass 100000
80000 Catch Catch (Mt) 60000
40000 20000 Catches
0 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Year
Source: Worm et al. (2007) Science 316:1282-1284
Diversity and services recover
Source: Worm et al. 2006. Science 314:787-790 Catch shares can halt collapse
Catch share
Open access
Source: Costello et al. (2008) Science 321:1678-1680
Half full?
• 65-75% of high-yielding seafood stocks are thought to be still viable • Some regions are successfully rebuilding • Catch-share systems have proven useful • Protected areas often achieve rapid recovery
Source: The Economist, September 2008 Part III: Solutions
Reduce fishing mortality below Fmsy
OLD TARGET OLD NEW TARGET NEW
Source: Collie et al., unpublished
Control effort displacement
Source: Alders & Sumaila (2004) Fisheries Centre Report Realign incentives
• Remove harmful subsidies • Re-invest in rebuilding • Build catch share systems where feasible • Improve ocean governance, transparency and enforcement Protect biodiversity
• Increase protected areas • Improve gear selectivity • Protect vulnerable habitats • Fight climate change Ban wasteful practices
Photos from: www.marinephotobank.org
Bottom line
• The situation is dire, but we know how to fix it • We can not give up on wild fisheries • Biodiversity maintains fisheries and other ocean ecosystem services • New focus on REBUILDING FISHERIES ECOSYSTEMS • It’s not too late – we just need to do it Thank you
• Ransom Myers † • NCEAS Group: Linking • Heike Lotze marine biodiversity to ecosystem functions and services • NSERC • NSF • NCEAS Group: Finding • Lenfest Ocean Program common ground in marine conservation • Census of Marine Life and management