Overview
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Commercial
fishing pressure is an indicator of how the large-scale harvesting of
free-ranging fish from coastal waters and high seas can impact the success of
future catches of wild fish. This includes catch and bycatch (both high and
low) of fish, other seafood and marine wildlife.
While global fishery resources supply humans with
a significant portion of their protein needs, they may also inflict pressure on
the environment through overfishing, the catch of unintended species, and the
use of destructive or unregulated fishing methods that can result in high
levels of bycatch, i.e. the catch of unintended species or undersized/underaged
specimens of a target species.
How Was It Measured?
Commercial
Fishing, High Bycatch
Modeled
demersal and pelagic high bycatch fishing pressure.
This
Pressure represents fish caught using high bycatch gear, which includes
demersal destructive (e.g. trawl), demersal non-destructive (e.g., pots, traps)
and pelagic (e.g., long-lines) gear. Spatially-explicit global estimates of catch by five different gear types associated with high bycatch and the two associated with low bycatch were then calculated for each region. Pressure per gear class per region was calculated as the mean of all 1km pixel values within the region. The maximum possible score (which is used to
rescale all values 0-1) was set at 110% of the maximum regional score
from previous years. High bycatch
commercial fishing was then measured as the average of demersal destructive
(e.g., trawl), demersal non-destructive high bycatch (e.g., pots, traps) and
pelagic high bycatch (e.g., long-line) gear.
All pressures have different affects on different goals. For each goal, the affect of each pressure is weighted 'low' (1), 'medium' (2) or 'high' (3). The actual data-derived value of the pressure is then multiplied by the weight assigned to it for that goal. That process is repeated for each pressure-goal combination. The sum of those values divided by 3 (the maximum pressure-goal value) expresses the total affect of that pressure on the goal.
Commercial Fishing (High Bycatch) has a high effect (weight = 3) on Food Provision (Fishing), Livelihoods and Economies (Commercial Fishing), and Biodiversity (Habitats: Soft Botton, and Species). It has a medium effect (weight = 2) on Artisanal Fishing Opportunity, and Sense of Place (Iconic Species). It has a low effect (weight = 1) on Livelihoods and Economies (Marine Cetacean Watching).
Commercial
Fishing, Low Bycatch
Modeled
demersal and pelagic low bycatch fishing pressure.
Methods for this Pressure were identical to those for Commercial Fishing, high bycatch, but calculating the area exposed to fisheries using demersal
non-destructive (e.g. hook and line) and pelagic (e.g. purse seine) gear.
Commercial Fishing (Low Bycatch) has a medium (weight = 2) on Natural Products (Fish Oil). It has a low effect (weight = 1) on Food Provision (Fishing), Artisanal Opportunity, Livelihoods and Economies (Commercial Fishing), and Biodiversity (Habitats: Soft Bottom, and Species).
Full details for this data layer are provided in Halpern et al. (2008) and Halpern et al. (2015).
What Are The Impacts?
ECOLOGICAL IMPACT
Increasingly
intense large-scale fishing has spread throughout the ocean. Fishing pressure
and destructive fishing techniques have led to the depletion, or even collapse,
of major fish stocks.
Though
declining exploitation rates have contributed to the rebuilding of some
depleted stocks, on average, fish stocks are still well below maximum
sustainable yield (maintaining the population size
at the point of maximum growth rate) in most regions (Worm et al. 2009).
Overfishing
can affect the population size of threatened or endangered species as well as
the potential future catch of targeted fish stocks.
At
least 32% of assessed commercial species are overexploited or depleted and a
further 53% are already exploited to their maximum capacity (FAO 2010).
Unsustainable
fishing pressure alters marine ecosystem structure and can have a significant
impact upon biodiversity, productivity, and overall food web dynamics.
Destructive fishing practices result in bycatch,
which is the catch of unintended species or undersized/underaged specimens of
the target species. Bycatch of non-target species can harm the ecological
structure of an ecosystem, affecting existing populations as well as potential
future catch. Species other than fish, including whales, sharks, dolphins, sea
turtles and sea birds die as bycatch from the use of nets and longlines (Davies
et al. 2009).
Although some countries utilize bycatch for food
and/or fishmeal, non-target species are usually returned to the water when they
are dying or already dead.
HUMAN HEALTH IMPACT
Oceans
provide food for billions of people worldwide. Fish are highly nutritious, rich
in essential minerals, micronutrients, essential fatty acids and proteins.
Fish
provide more than 3 billion people,
particularly in low-income, food deficient countries, with 15 percent of their
average per capita intake of animal protein (FAO 2010).
If
overfishing did not exist, global fisheries could
have prevented malnourishment for nearly 20 million people and total
catch in the waters of low-income, food deficit, nations might have been up to
17% greater than the tonnage actually landed there
(Srinivasan
et al. 2010).
The
global demand for seafood continues to rise, while 40% of fisheries are
actually decreasing in production and overfishing remains a major threat to
seafood availability (Peterson and Fronc 2007).
ECONOMIC IMPACT
While there are tremendous economic and social
benefits from fishing, overfishing can have significant adverse socioeconomic
effects. The depletion of global fish stocks constitutes a loss of global
natural capital and when fish stocks are fully exploited physically, associated
fisheries are almost invariably performing below their economic optimum (World
Bank 2008).
Net losses to the global economy from
unsustainable exploitation of living marine resources are calculated to
substantially exceed US $50 billion per year- equivalent to more than half the
value of the global seafood trade (World Bank 2009).
Fisheries and aquaculture (both marine and
freshwater) together employ about 44.9 million people worldwide. Each of these
jobs produces approximately three secondary jobs, leading to a total of
approximately 180 million people employed in the sector.
On average, each job holder supports three
dependents or family members, so the livelihoods of about 540 million people
worldwide--8 percent of the world population in 2008—were dependent on
fisheries and aquaculture (FAO 2010).
Wild fisheries contributed between US $ 225-240
billion to the global economy in 2003 (Dyck and Sumaila 2010).
What Has Been Done?
Valuable
stocks of haddock, scallops, pollock, and swordfish in the U.S. North Atlantic
that previously suffered from decades of overfishing have now been brought back
to relatively healthy levels. They are part of 21 stocks that have been rebuilt
nationwide in the United States since 2000, using standards set by the U.S. National Marine Fisheries Service and
Regional Fishery Management Councils according to requirements set by the
U.S. Magnuson-Stevens Act.
National Oceanic and Atmospheric
Administration [NOAA]
New Zealand was the first country to comprehensively implement catch shares for their commercial fisheries, creating what is now called the Quota Management System (QMS). The QMS was created to increase the economic and export value and profitability of fisheries, while ensuring sustainability. Currently, approximately 100 species are included in the program and many once-depleted stocks have been rebuilt, with nearly 70% of the catch share stocks at or near target levels (Bonzon et al. 2010).
Get More Information
Consortium for Wildlife: Bycatch Reduction
A database of collaborative research between the fishing industry and the scientific community that aims to reduce bycatch for endangered species.
World Wildlife Fund (WWF): Smart Gear Competition
Created in partnership with industry leaders, scientists, and fishers, the competition encourages fishers to reduce the incidental catch of non-target species in fishing gear.
Sustainable Fisheries Partnership (SFP)
FishSource is a global fisheries online database created for seafood buyers and contributors.
Food and Agriculture Organization of the United Nations: Fisheries and Aquaculture Department
An index of fisheries’ global information networks.
WorldFish Center
An international publication database dedicated to reducing poverty and hunger by improving fisheries and aquaculture.
References
Committee on Ecosystem Effects of Fishing: Phase II - Assessments of the Extent of Change and the Implications for Policy, National Research Council. 2006. Dynamic Changes in Marine Ecosystems: Fishing, Food Webs, and Future Options. The National Academies Press: Washington, D.C., 2006.
Dulvy, N. K., Y. Sadovy and J.D. Reynolds. (2003). Extinction vulnerability in marine populations. Fish and Fisheries 4, 25–64.
Laurenti, G. (2007). Fish and fishery products: World apparent consumption statistics basedon food balance sheets. FAO Fisheries Circular 821, rev. 9. Rome, Italy: FAO.429 pp.
Ling, S. D., C.R. Johnson, S.D. Frusher and K.R. Ridgway. (2009). Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift. PNAS (2009).doi:10.1073/pnas.0907529106
Lock, K. and S. Leslie. (2007). New Zealand’s Quota Management System: A History of the First 20 Years. (Motu Economic and Public Policy Research 2007).
Swartz, W., E. Sala, S. Tracey, R. Watson and D. Pauly. (2010). The spatial expansion and ecological footprint of fisheries (1950 to Present). PLoS ONE 5, e15143 (2010).
Watson, R., C. Revenga and Y. Kura. (2006). Fishing gear associated with global marine catches: II. Trends in trawling and dredging. Fisheries Research 79, 103–111.
