Can early life survival be a factor that affects the survival of marine groundfishes in the Gulf of Alaska?

Photo Credit: S. Ian Hartwell

Explore the Science

The Gulf of Alaska Project is multi-disciplinary and brings together over 45 experts in various fields of marine science to address broad ecosystem-level questions over five years (2010 - 2014).  This collaborative effort will allow us to achieve a higher level of understanding than any one researcher would be able to achieve on his or her own.  Experts in physical, chemical, and biological oceanography, fisheries, seabird and marine mammal science, and ecological modeling are all participating in this study.  

Photo Credit: Wyatt Fournier

This aspect of the project is testing the central hypothesis that early life survival is the primary factor that determines the year-class strength of marine groundfishes in the Gulf of Alaska.  This project focuses on five commercially and ecologically important groundfish species: Pacific cod, pollock, Pacific ocean perch, sablefish, and arrowtooth flounder.  Year-class strength determines how many adult fish are available for commercial fisheries, therefore the results of this project are important to fisheries managers and Alaska's economy.  

This component of the project is testing several hypotheses about forage fish in the Gulf of Alaska and the role that they may play in affecting the survival of the five focal groundfish species during their first year of life.  Forage fish are the fish that many large fish, seabirds, and marine mammals eat.  They include fish like herring, capelin, and sandlance that do not grow to large sizes as adults.  Forage fish also include the juvenile stages of larger fish, including the five focal groundfish species.  

Photo Credit: Wyatt Fournier

Photo Credit: Jamal Moss

This aspect of the project focuses on the physical and biological oceanography that influences the survival of the five focal groundfish species (Pacific cod, pollock, Pacific ocean perch, sablefish, and arrowtooth flounder) during their first year of life.  Oceanographers are testing the hypothesis that cross-shelf and along-shelf transport of nutrients and plankton differs in the central and southeast Gulf of Alaska and that the mechanisms controlling primary production differ as a result.  They are also testing the hypothesis that the food webs leading to larval and juvenile fish differ between these regions.

Ecosystem modeling is being used to determine which environmental conditions have the greatest effect on the survival of the five groundfish species that are the focus of this study (walleye pollock, Pacific cod, Pacific ocean perch, sablefish and arrowtooth flounder). A series of models is used to examine the effects of oceanography, current patterns, nutrient availability, food availability, predator interactions, and various combinations of these factors on how these fish survive under different conditions. 

Courtesy: Franz Mueter 

Photo Credit: Morgan Ostendorf

Retrospective analyses allow us to put the data collected during this short-term study into context by examining patterns in historical data collected over the past few decades.  Examining long-term patterns allows us to ask informed questions about the possible environmental drivers of fish survival and recruitment in the Gulf of Alaska.