OVERVIEW OF STATE-MANAGED MARINE FISHERIES IN THE CENTRAL AND WESTERN GULF OF ALASKA, ALEUTIAN ISLANDS, AND SOUTHEASTERN BERING SEA, WITH REFERENCE TO STELLER SEA LIONS
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... These emergency orders establish parallel fishing seasons (termed "parallel fisheries") allowing vessels to fish for groundfish (primarily Pacific cod, walleye pollock, and Atka mackerel) in state waters with the same seasons as the federal fisheries. In other instances, the State of Alaska establishes "state waters" (or state-managed) fisheries with separate catch quotas (termed GHLs in state management), and fishing seasons under state groundfish regulations (Kruse et al. 2000). Where there is a federal and parallel fishery for a species, the state waters fishery usually opens after the parallel fishery closes. ...
... Cod enter the fishery about age 7 and may live 19 years or more. Primary products from the cod fishery include a headed and gutted (H&G) product, fillets, and to a lesser extent salted, whole fish, and roe (Kruse et al. 2000). ...
... The oldest groundfish fishery off Alaska targets Pacific cod. The developing fishery peaked during 1916-1920 and steadily declined to 1950 (Kruse et al. 2000). Pacific cod supported large foreign fisheries in the Bering Sea during the 1960s and early 1970s. ...
... Unless otherwise noted, the following review of red king crab fisheries is summarized in Table 2 from the synthesis of Kruse et al. (2000) and updated by Woodby and Hulbert (2006). King crab fisheries in the Gulf of Alaska were initiated by Japanese fishermen in the late 1930s and small domestic catches were also taken. ...
... Crab population abundances and catches in Alaska have fluctuated greatly over time (Zheng et al., 1995Zheng et al., 1998b;Kruse et al., 2000). The abundance of commercial-sized red king crab (Paralithodes camtschaticus) in the Gulf of Alaska peaked in 1965 with a catch of 51,427 t. ...
During the last three decades, population abundances of eastern Bering Sea (EBS) crab stocks fluctuated greatly, driven by highly variable recruitment. In recent years, abundances of these stocks have been very low compared to historical levels. This study aims to understand recruitment variation of six stocks of red king (Paralithodes camtschaticus), blue king (P. platypus), Tanner (Chionoecetes bairdi), and snow (C. opilio) crabs in the EBS. Most crab recruitment time series are not significantly correlated with each other. Spatial distributions of three broadly distributed crab stocks (EBS snow and Tanner crabs and Bristol Bay red king crab) have changed considerably over time, possibly related in part to the regime shift in climate and physical oceanography in 1976–1977. Three climate-forcing hypotheses on larval survival have been proposed to explain crab recruitment variation of Bristol Bay red king crab and EBS Tanner and snow crabs. Some empirical evidence supports speculation that groundfish predation may play an important role in crab recruitment success in the EBS. However, spatial dynamics in the geographic distributions of groundfish and crabs over time make it difficult to relate crab recruitment strength to groundfish biomass. Comprehensive field and spatially explicit modeling studies are needed to test the hypotheses and better understand the relative importance and compound effects of bottom-up and top-down controls on crab recruitment.
... Finally, there is a considerable database on Steller sea lions because of their endangered status, and the possible implications of the highly valued walleye pollock (Theragra chalcogramma) fishery in their decline (Ferrero and Fritz, 2002). The National Marine Fisheries Service (NMFS) has conducted periodic aerial surveys of Steller sea lions on various haulouts and rookeries for several decades (Kruse et al., 2000; Sease et al., 2001). There are 13 years with NMFS counts of Steller sea lions in PWS and vicinity between 1973 and 2004, including five made during the critical post-EVOS years 1989– 1993 (Table 1). ...
Thorne, R. E., and Thomas, G. L. 2008. Herring and the "Exxon Valdez" oil spill: an investigation into historical data conflicts.
– ICES Journal of Marine Science, 65: 44–50.It was generally believed that the 1989 “Exxon Valdez” oil spill did not cause the collapse of the Prince William Sound Pacific
herring (Clupea pallasi) population because of a 4-year gap between the spill and the collapse. However, we noted in a previous paper that some data
suggested an earlier timing for the herring decline. We examine historical patterns of herring spawn, anomalies in historical
fisheries model predictions, changes in predation behaviour of Steller sea lions (Eumetopias jubatus), and a decadal database of acoustic measurements of herring biomass. Behaviour of adult herring makes them especially vulnerable
to damage from oil spills, something that was either unknown or misunderstood at the time of the spill. We therefore argue
that the start of the herring decline was coincident with the oil spill, and that the decline took place over a 5-year period,
rather than the single-year collapse previously reported. Although a comprehensive management approach is now in use for herring,
the tools were not in place at the time of the oil spill or the subsequent collapse.
This chapter discusses the ecological change that occurs over different timescales. Long-term measures of physically important variables are salinity, precipitation, nutrients, stratification, currents, and coastal wind fields are relatively rare. Climate change, whether of natural or anthropogenic origin, brings with it uncertainty and the potential to upset existing economic and social. structures. The barrier to understanding long-term changes in the Gulf of Alaska (GOA) is the complex nonlinear structures that characterize these systems. The space and timescales of physical and biological variables are different from one another and the relation between a physical change and a biological response might be indirect, nonlinear, and involve several other system components. The observations are used in conjunction with models to evaluate model performance and/or to constrain model predictions and hindcasts. Variations have been detected in winds, surface heat fluxes and runoff, water temperature and salinity, mixed-layer depth, nutrient supply, and circulation properties. The temperature of the ocean at a given location is controlled by heat exchange with the atmosphere, mixing with waters of different temperatures, and the advection of heat into or out of a region by ocean currents. The long-term record of salmon abundance comes from two sources - the historical record of the fisheries and geochemical records in sockeye salmon lake sediments. Development of comprehensive life-stage-based models is one step toward understanding the causes of shrimp and crab population changes in the northern Gulf of Alaska.
An integral part of assessing the northern Gulf of Alaska (GOA) ecosystem is the analysis of the food habits and feeding patterns of abundant zooplanktivorous fish. Juvenile pink salmon Oncorhynchus gorbuscha are highly abundant zooplanktivores, and support valuable commercial fisheries as adults. We document variability in pink salmon distribution and size from summer to early fall, and present major trends in their food habits by summarizing interannual (August 1999-2001), seasonal (July-October 2001) and diel (August 2000, and July-September 2001) feeding patterns based on analysis of stomach contents of juvenile pink salmon collected along the Seward Line (GOA) and in Prince William Sound (PWS), Alaska. Diets of juvenile pink salmon were more diverse in 2001 compared to either 1999 or 2000. Small pteropods (Limacina helicina) composed the majority (> 60%) of prey consumed in 1999 and 2000; whereas large copepods, euphausiids, and small pteropods composed the majority of prey in 2001. As juvenile pink salmon increased in size, they consumed increasingly larger prey from August to October 2001 in the GOA. The diet of GOA juvenile pink salmon was different and more diverse than the diet of fish caught in PWS. The dominant prey in PWS during July-October was hyperiid amphipods, whereas the primary prey in the GOA were larvaccans and euphausiids in July, then copepods plus small pteropods, amphipods, euphausiids, larval crabs, and shrimp in August.
Risk measures can summarize the complex variability inherent in fisheries management into simple metrics. We use quantitative risk measures from investment theory to analyze catch and revenue risks for 90 commercial fisheries in Alaska, USA, nearly a complete census. We estimate the relationship between fishery characteristics and catch risk using nonparametric random forest regression to identify attributes associated with high or low risks. Catch and revenue risks for individual Alaskan fisheries are substantial and are higher than risks for farmed food alternatives. Revenue risks are greater than catch risks for most fisheries, indicating that price variability is an additional source of risk to fishermen. Regression results indicate that higher productivity species tend to be higher risk, and there is an increasing gradient of risk moving north and west across Alaskan waters, with the remote western Bering Sea fisheries tending to have the highest risks. Low risk fisheries generally have large catches and support larger fleets. Finally, fisheries with greater catch history under some form of dedicated access privileges tend to have lower catch risks.
Evidence of direct mortality to fishes exposed to oil is very limited. The 1989 Exxon Valdez oil spill had major impacts on marine mammals and seabirds, but was not implicated in the 1993 collapse of the Prince William Sound herring population because of the four year gap. However, we use several independent evidences, including changes in the predation behavior of Steller sea lions, to show that the collapse actually began in 1989. We show the failure to detect the actual timing of the collapse was due to deficiencies in the fishery model used to assess herring population abundance and lack of understanding about the vulnerability of herring. Finally, we show that the oil spill actually had greater impacts than originally believed as a result of catastrophic impacts on the ecosystem from the herring collapse
This paper examines the ratio of the weight of the herring catch to the total weight
of the ground fish catch in observer records from Pacific cod (Gadus
macrocephalus) and pollock (Theregra chalcogramma) bottom trawl tows, in order
to define an index of herring abundance. The index is used to determine the
timing and location of herring stocks during their annual migration . This index
would be expected to fluctuate with ground fish density as well as with herring
density.
However, because the herring migration is a relatively distinct phenomenon, the index is sufficient to delineate the general movements of
herring during the annual migration . Also, over the 1983 through 1988
period, the abundance of both herring and groundfish stocks was relatively
constant.
Stomach contents consisted by volume of 95.7% fishes, 4.2% cephalopods, <0.1% decapod crustaceans, <0.1% shelled-gastropods, and <0.1% mammals. The 10 top-ranked prey were walleye pollock Theragra chalcogramma; squids, Gonatidae; Pacific herring Clupea harengus pallasi; capelin Mallotus villosus; Pacific cod Gadus macrocephalus; salmon Oncorhynchus spp.; Octopus sp.; sculpins, Cottidae; flatfishes, Pleuronectidae; and rockfishes, Scorpaenidae. Walleye pollock comprised c.58% of the total volume and occurred in 67% of stomachs with food. Predation on capelin and salmon appeared to be largely limited to spring and summer. There was nearly complete overlap in the diet of sea lions and harbor seal Phoca vitulina richardsi. Potential competition may have been ameliorated by differences in distribution, differing diving capabilities, a more diverse diet for harbor seals and use of larger prey by sea lions.-from Author