Smaller than a pencil tip, crab larvae (above) hatch in an experimental effort to replenish a climate-stressed population that has seen no targeted fishing since 1999, when managers closed it. The Council has been tightening protections for these faltering crabs in the Pribilof Islands since 1995, even halting other fisheries near the islands to prevent modest bycatch impacts.
Currently, stock assessment scientists assume natural reproduction is so impaired—by effects of warming waters and a diminished breeding population—that recovery by natural reproduction is a remote prospect at best. Meanwhile, researchers and fishermen are collaborating in efforts to develop hatchery techniques that may permit humans to give this crab a boost.
Broader strategy: The Council proactively anticipated effects of rapid environmental change in the northern latitudes, enacting a precautionary moratorium on Arctic commercial fishing in 2009. Concerned that fishing fleets might follow fish stocks and retreating ice into largely unfished high-latitude habitats, the Council restricted several delicate seabed ecosystems in the Northern Bering Sea. Beyond warming , research on changes in ocean chemistry, circulation, coastal habitats, and marine foodwebs now guides managers in crafting fishing rules to ensure that a changing ocean can continue to feed people—some of whom have relied on these waters since before recorded history.
Bob Foy, NOAA, pers. comm. in emails to Brad Warren May 2 and May 10, 2016
Anticipating that new fisheries could emerge as ice retreats, in 2009 the North Pacific Council placed a moratorium on commercial fishing in US Arctic waters until research provides the necessary scientific foundation to sustainably govern fisheries there. Managers chose “to be proactive and precautionary,” acting “before an unregulated commercial fishery develops,” noting that warming, retreating ice, and lack of research could make Arctic ecosystems especially vulnerable. One example: Arctic waters off Alaska’s western shore are famously rich with tiny seabed-dwelling crustaceans (especially amphipods) and other invertebrates. This resource attracts gray whales from as far south as Mexico to summer feeding grounds where they bulk up for the year by scraping the seafloor, eating about 1.3 tons of food each day. The moratorium protects Arctic feeding grounds from potential fishing impacts.
A tight watch on biomass (gray) and incoming young fish enables managers to adjust catch limits quickly as stocks fluctuate for any reason. Between 2004 and 2010, the Council reduced catch limits (TAC, orange) on Eastern Bering Sea pollock by 45%, steering the nation’s largest fishery (by volume) through a decrease in biomass. The stock rebounded. NOAA researchers later linked the decline to foodweb changes during a four-year warm period in the Bering Sea (2002-2005). They found evidence that many newly-hatched pollock failed to bulk up enough to survive their first winter. Why? The leading scientific hypothesis suggests a decline in prey quality linked to warm conditions. NOAA scientists report that large copepods and krill—rich feed for young pollock—dwindled because they lost access to their own prey due to a chain of ecosystem effects triggered by early ice melt. The return of cold, icy years is thought to have helped to restore strong feed conditions, while tighter catch limits protected the pollock stock’s capacity to rebuild.
Recognizing that warming may be shifting fish stocks northward, the Council has sought to protect sensitive habitats, respect local community concerns about bottom trawling, and allow responsible fishing practices that allow fleets to adapt to a changing environment.
In 2008 the Council prohibited bottom trawling in the 212,400 km2 Northern Bering Sea Research Area (NBSRA), pending completion of an environmental study to understand effects of modified, low-impact trawl gear, in addition to federal consultations on endangered and threatened species in the area.
The Council also closed 24,416 km2 around St. Lawrence Island and protected another 33,534 km2 of waters encompassing several areas: Nunivak Island, a rare pocket of blue king crab habitat around St. Matthew Island, and waters along Western Alaska’s coast near the Kuskokwim River delta. In 2010 the Council expanded the protected area for blue king crab habitat around St. Matthew. Responding to shifting flatfish distribution, the Council’s 2010 action also adjusted rules within a narrow strip comprising about 5 percent of the Research Area; this became part of a new 11,270 km2 zone where only low-impact trawl gear is permitted. The Council designed this Modified Gear Trawl Zone (MGTZ) to minimize damage to seabed habitats while allowing continued flatfish harvests in a changing ocean.
In a tribal consultation with NOAA, the village of Unalakleet opposed any bottom trawling in the Research Area. NOAA responded, in part: “NMFS understands that the concern of the tribal representatives is primarily on the potential adverse impact that non-pelagic trawling may have…on bottom habitat that supports subsistence resources. Because the regulations require the use of modified nonpelagic trawl gear in the MGTZ, the potential impact on bottom habitat…is reduced. The rest of the NBSRA remains closed to commercial nonpelagic trawling.” The rule specifies design requirements to elevate the trawl and its towing bridles and minimize benthic impacts.
Blue king crab stocks have collapsed in the Pribilof Islands, and NOAA scientists speculate warmer seas and associated environmental changes –which disrupt settlement and survival for tiny larvae of this cold-water crustacean—are keeping the battered population from rebounding. The Council has closed fishing to fisheries that could further affect blue king crab near the island. The Pribilof Island Habitat Conservation Area (left-hand yellow highlighted area), established in 1995, restricts trawling in a 24,009 km2 box defined by blue king crab habitat. Download map as pdf, here.