Principle 2

Do managers prevent overfishing of both target and non-target species?


By design, fishing removes only a small fraction of groundfish biomass in the North Pacific.

Layers of precaution buffer against the chance of overestimating safe limits for sustainable harvest, both for target species and nontarget species caught incidentally. Ecosystem caps put a ceiling on total removals, leaving fish for natural predators and ecosystem needs.

Bycatch is any species caught incidentally to the target fish.  Every fishery has some kind of bycatch.  The friction comes when one fishery’s bycatch is another fishery’s target species.  To reduce bycatch, managers, fishermen and scientist have developed a toolkit of policies and clean fishing practices.

Results? Declining bycatch of halibut, crab, and salmon, and better utilization of groundfish. This reflects decades of painstaking work to make fishing gear more selective, create and refine a network of mandatory closed areas, and modernize older management policies that sometimes inadvertently pushed fishermen into bycatch and waste.


Layers of precaution build fisheries to last

Science drives the catch limits that keep North Pacific fisheries healthy.

Each year, NOAA scientists survey the biomass of groundfish off Alaska. Using this data, they calculate conservative limits on harvest:

  1. The Overfishing Level (OFL): a ”red line” never crossed. North Pacific managers draw this line far more conservatively than many of their peers worldwide. Indeed, many governments still aspire to reduce fishing pressure enough to reach levels that are formally designated as excessive and out-of-bounds in the US North Pacific. For fishing levels used in comparable groundfish fisheries worldwide, see
  2. Acceptable Biological Catch (ABC): estimated maximum sustainable harvest. Scientists calculate this limit using cautious harvest rates that are designed to ensure fish stocks are replenished.
  3. Total Allowable Catch (TAC): North Pacific fishery managers set catch limits that never exceed the sustainable ABC.




Bering Sea

Leaving Plenty of fish in the Bering Sea

This chart reveals why fishery managers around the world regard the US North Pacific region as a model of sustainable management, especially for groundfish (cod, pollock, flatfish, and other fish that are often found near the seabed).
Biomass (gray) towers above catch (green), ensuring plenty of fish stay to replenish stocks, feed natural predators, and contribute to ecosystems.
Catch rarely exceeds catch limits (blue), a sign of strong compliance.
Catch limits are kept within scientific guidelines for the Acceptable Biological Catch (ABC, yellow).
Managers avoid harvest levels that could overfish the resource (red). The harvest policy underpinning this practice embraces uncertainty and gaps in scientific knowledge about fish stocks, treating them as cues to increase precaution.

Harvest guidelines vs biomass in BSAI (million metric tons)




Gulf of Alaska

Leaving Plenty of Fish in the Gulf of Alaska

There is a simple reason why the North Pacific supplies about 60% of all US landings by volume.

Managers and fishermen keep catches (green) and catch limits (blue) safely within levels recommended by scientists (yellow). Fishermen consistently accept some economic pain today in order to sustain plentiful biomass (gray) and abundant harvests tomorrow. Notably, the harvest policy converts uncertainty into precaution. This permits moderate fishing on well-understood stocks, while scaling down fishing on stocks about which less is known.

Harvest guidelines vs biomass in GOA (million metric tons)




Pollock: rebuilt after foreign overfishing

Confronting unsustainable fishing by foreign fleets, in the late 1970s the newly formed North Pacific Fishery Management Council slashed harvests on pollock in the Eastern Bering Sea, rebuilding the stock. Reduced catches allowed rapid growth in biomass. Ever since, the Council has maintained catch limits that allow biomass to be at levels that leave a wide precautionary buffer to protect the future of the fishery, the resource and its many roles in the ecosystem.

F/Fmsy (orange) indexes fishing mortality (F, a standard measure of fishing pressure) against the amount of fishing allowable at maximum sustainable yield: 1 on the vertical axis. This shows harvests are kept at a fraction of maximum levels.

B/Bmsy (blue) indexes biomass (B) against its level at maximum sustainable yield: 1 on the vertical axis. This shows that the Council maintains catch limits that allow biomass to be well above the Bmsy standard, ensuring that more than enough fish remain in the water to reproduce and support predators that feed on this resource.

In most years the ratio of the Eastern Bering Sea pollock harvested (spawning exploitation rate) is less than 20%, leaving about 80% of the biomass in the water.




No groundfish

Preventing overfishing

None of the 26 major groundfish stocks (and stock complexes) across the BSAI and GOA are overfished or experiencing overfishing.

Pacific Ocean

Pacific Ocean Perch: Recovered

Long-lived and slow-growing, Pacific Ocean Perch were overfished by foreign fleets—especially in the Gulf of Alaska—until the late 1970s. Biomass began to recover with US control of the 200-mile zone, when managers implemented sustainable fishing limits. The Council tightened harvests further in the 1990s, and currently holds catch limits below 8.9% of biomass in the BSAI, and below 11.2% in the GOA. Spawning biomass in both basins has tripled under Council management, and stock today is healthy.

GOA Catch vs Biomass (metric tons)
BSAI Catch vs Biomass (metric tons)

Building the Bycatch Toolkit

Beyond preventing overfishing, North Pacific managers have worked for decades with scientists and fishermen to curtail the troubling take of unmarketable and prohibited species in fishing gear.

Every fishery catches the wrong fish sometimes. Often, that fish is somebody else’s livelihood. Fishermen hold each other accountable. This accountability drives improvement. Managers, fishermen and collaborating scientists in the North Pacific have built a remarkable toolkit of policy, science, and fishing technology to drive down bycatch.

What's in the kit?
  • Research hones gear to reduce bycatch and habitat impacts.
  • Rationalization (catch shares) provides the stability necessary for fishermen to fish more slowly and strategically, minimizing the catch of undesirable fish.
  • Rules require cleaner-fishing technology, prohibit discards of unwanted fish, mandate careful handing of prohibited species.
  • Data driven real-time closures help pollock fleet avoid salmon “hot spots”.
  • Permanent or seasonal closures restrict fleets in high-bycatch-areas for crab, salmon, halibut, herring, and other species.

Sharing Salmon Hotspot Data

Dynamic Closures Reduce Salmon Bycatch

Sharing bycatch data to locate salmon “hot spots” enables Bering Sea pollock fishing cooperatives to move member vessels out of areas with higher amounts of salmon. Red circles ● mark the highest salmon concentrations (guiding shape and location of closures). Red stars ★, green stars ★, and blue crosses + signify progressively lower concentrations of salmon— indicating better waters to chase pollock.

Salmon Avoided
(Estimated savings from vessels moving out of hot spots in 2013)
Chinook: 74%
Chum: 65%

Avoiding salmon is a priority of pollock trawlers, who feel the sting when coastal fishing communities across Alaska demand tighter limits on bycatch that nibbles into their own salmon harvests. Trawlers don’t target salmon, and legally can’t sell them. When incidentally caught salmon meet specific criteria, they can be processed and donated to food banks. But avoiding salmon can be tricky when they occasionally mingle with pollock.

Along with adapting their gear and timing their harvest to avoid salmon, the Council oversees an innovative industry program that closes salmon “hot spots” in real time. Pollock fishing cooperatives use an independent monitoring firm (Sea State) to track salmon bycatch using satellite and observer data. The co-ops close salmon hot spots as needed. Unlike federal managers, they can impose closures fast enough to save salmon, using contracts to bind members to comply.




Avoiding Halibut

In recent years, the North Pacific has seen a downward trend in adult halibut biomass.  The number of incidentally caught halibut has steadily declined likely reflecting both bycatch reduction measures implemented by the Council and the reduction in adult halibut biomass.  Key bycatch reduction measures include; trawl modifications, gear restrictions, area closures, regulatory bycatch limitations, reducing handling mortality, and careful in-season management by fishing cooperatives to avoid bycatch.  Since halibut share the seafloor with multiple groundfish species, some bycatch is inevitable, but steady progress marks the road.

Halibut Mortality in Federal Hook and Line and Trawl Groundfish Fisheries





Selective Fishing Technology

“Excluder” devices (carefully engineered exit holes in the net) reduce bycatch of halibut and salmon in North Pacific groundfish fleets by taking advantage of differences in fish behavior. Effective designs retain most target fish while encouraging prohibited species (in this case halibut) to leave. Approximately 80% of halibut escaped through this device in experiments authorized by the Council in the Gulf of Alaska, while only 20% of Pacific Cod (the target species) were lost. Use of excluders helps trawlers stay below their bycatch caps, so they can pursue their target species while freeing more halibut for other fleets that depend on this big flatfish. Decades of research by NOAA and industry groups have gradually improved performance of excluder devices.

Species escape rates using halibut excluder in GOA cod trawl
Halibut Escapes through slots at right

Principle 2 Closures

Interactive Map: History and Purpose of Closures