A review of the distribution, ecology and population dynamics of age‐0 walleye pollock in the Gulf of Alaska

• Published in: Fisheries Oceanography
• Main Authors: BRODEUR, RICHARD D., WILSON, MATTHEW T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1996
• Subjects: Gulf of Alaska; fratercula; Kodiak; Phoca vitulina; Theragra chalcogramma; Alaska; Copepods
• Online Access: http://dx.doi.org/10.1111/j.1365-2419.1996.tb00089.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2419.1996.tb00089.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2419.1996.tb00089.x

ABSTRACT This review paper synthesizes published research and unpublished data on the abundance and distribution patterns, ecology and population dynamics of walleye pollock ( Theragra chalcogramma ) during their first year of life (age‐0) in the Gulf of Alaska. Distribution patterns have been described using mainly trawl catches, but recently, acoustic methodology has been employed, especially in examining vertical distributions. Although age‐0 pollock are found throughout the Gulf, the highest catches occurred west of Kodiak Island. Pollock are pelagic for at least their first 6 months of life but show an ontogenetic increase in depth distribution superimposed on a pronounced diel vertical migration at a larger size. Daily growth rates are variable depending on year, season and area, and growth generally ceases during the winter. The diet of age‐0 pollock shifts from mainly copepods in early juveniles to euphausiids by fall, with epibenthic organisms becoming important during the winter months. Feeding occurs mainly at night in surface waters. Age‐0 pollock are most frequently associated with gelatinous zooplankton (medusae) and older pollock. Many predators on age‐0 pollock have been identified; the most important are arrowtooth flounder ( Atheresthes stomias ), adult pollock, puffins ( Fratercula spp.), murres ( Una spp.), harbor seals ( Phoca vitulina richardsi ) and Steller sea lions ( Eumetopiasjubatus ). Modelling provides some insight into the population dynamics of these juveniles and environmental conditions which interannually affect their survival. These results are discussed relative to the importance of age‐0 pollock in the recruitment of this species and to their role in the pelagic ecosystem.