Pew Oceans Commission List Impacts of Ocean Fishingby Mike O'Bryant
Columbia Basin Bulletin - December 13, 2002
The unintended consequences of ocean fishing along United States shores is depleting fish populations, removing predators, endangering other marine animals and altering the productivity and resilience of marine habitats, according to a new report by the Pew Oceans Commission.
The report, titled "Ecological effects of fishing in marine ecosystems in the United States," said that the long-term health of ocean ecosystems is threatened by overfishing, the bycatch or incidental catching of species not targeted by fishermen, and by habitat damage. In fact, declining catch of some species has been obscured by misreporting, technical advances in fishing gear that makes it easier to locate and catch fish and in a trend towards lower trophic-level species as predators disappear, according to the report.
"For centuries, we have viewed the oceans as an infinite resource beyond our capacity to harm. We now know that this is not true," said Leon Panetta, chair of the commission. "Our oceans are more vulnerable and more valuable than we ever imagined. If we want to sustain America's proud fishing industry, then we need to take a hard look at how pollution, development, and fishing activities are harming the oceans."
Panetta added that only 5 percent of commercial fisheries in the late 1960s were considered overfished; that higher levels of fixed nitrogen from industry, cars and farms has caused more than 40 dead zones in oceans which are now devoid of life; and that crowding along coastlines (54 percent of people live along coastlines, which makes up just 17 percent of the nation's lands) is altering sensitive habitats.
The report said that harm is "severe, dramatic, and in some cases, irreversible." Authors said that fishing which depletes populations of fish species alters the food webs and ecosystems; that removing predators disrupts predator/prey relationships; and that fishing can "Alter the structure, function, productivity, and resilience of marine habitats."
Although the U.S. government only has information about one-third of the ocean fish species it manages, according to the report, about one-third of those are overfished. That compares with worldwide overfishing estimated to be 25 percent to 30 percent. The problem reduces prey available to predators, setting off a ripple effect through the ecosystem and that is compounded by what is often called "serial overfishing." That's when fisherman move from one species as its population is decimated to the next species. "A final concern," the report said, is "fishing down the food web, where fishing shifts from higher trophic levels to lower trophic levels, resulting in a top-down ecological disruption."
About one-quarter of species caught up worldwide in nets and longlines is bycatch -- other fish, birds, turtles and marine mammals -- that are cast off and usually die. The report said bycatch has depleted most turtle species, several species of albatross and skates and rays. ".Bycatch extends the ramifications of fishing to a much wider sector of ocean life, with repercussions to the functioning and diversity of ecosystems," the report said. In addition, rocks, ledges, seagrass beds, sponge gardens, and shellfish beds in the ocean all contribute to juvenile fish survival, but fishing is having both temporary and long-term effects on this habitat.
While the authors point out the problem, they also offer some solutions and they sound very similar to those fisheries agencies are pursuing in the Columbia River Basin. Managers of ocean fisheries need to move away from managing one species at a time, to an ecosystem approach. Research and monitoring is needed and necessary. Proactive adaptive management is needed and ocean fishery management should be reoriented toward protecting natural resources. Dr. Paul Dayton of the Scripps Institution of Oceanography summed it up:
"Poor information on bycatch, discarding, and basic life history are the bane of fisheries scientists. Couple this with ineffective regulations, nonexistent brakes on developing capacity, and inadequate support of law enforcement, and disaster ensues. If we are to ensure sustainable fisheries-both commercial and recreational -- we must shift fishery management's emphasis from a single-species approach focused on short-term benefits to an integrated approach that acknowledges the tradeoffs we are willing to accept in our choice of management options."
Dayton shared authorship of the report with Simon Thrush of the National Institute of Water and Atmosphere Research (New Zealand), and Felicia Coleman of Florida State University.
The Pew Oceans Commission already has released other reports, including on marine pollution and aquaculture, and will release a report on the socio-economics of fishing in January 2003. The Commission will present its final recommendations for a new national ocean policy to Congress in March 2003.
Pew Oceans Commission: www.pewoceans.org
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