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Status of Stocks & Multispecies Assessment Program

Nearshore Surveys in the Gulf of Alaska

juvenile sandlance
Young-of-the-year Pacific cod and juvenile Pacific sand lance captured in a purse seine during nearshore surveys conducted by AFSC scientists in 2011.  Photo by Olav Ormseth.
 

Scientists from the AFSC's REFM and RACE Divisions conducted a series of nearshore surveys in the Gulf of Alaska during 2011. These surveys were a component of the Gulf of Alaska Integrated Ecosystem Research Project (GOA IERP), funded by the North Pacific Research Board (NPRB).

The GOA IERP is a multidisciplinary, comparative approach to understanding ecological variability at different trophic levels and over several temporal and spatial scales. Seasonal and regional variability are the key factors in the comparison. The main spatial comparison is between an eastern GOA region (basically the outer coast of southeast Alaska) and a western or central GOA region (the eastern side of Kodiak Island and the southern coast of the Kenai Peninsula).

Within each of the main regions, nearshore survey operations were conducted at five sites and were coordinated with an offshore survey to provide a synoptic view of the GOA ecosystem (Fig. 1). Nearshore surveys were conducted in the spring (April/May), summer (July/August), and fall (September/October).

figure 1, see caption
Figure 1.  Map of research activities conducted as part of the Gulf of Alaska Integrated Ecosystem Research Project.  Dots are the locations of research activities.

The nearshore surveys provided a comprehensive examination of the physical and biological characteristics of the sites, most of which were bays (e.g., Islas Bay in the east) or systems of bays (e.g., Port Dick in the west). At each site, 1-3 days were spent sampling fishes and habitat using a variety of gears.

  working on beach seine catch
An AFSC biologist works up a beach seine catch in Kiliuda Bay on Kodiak Island.  Photo by Olav Ormseth

In the eastern region, sampling occurred aboard the 54-ft chartered fishing vessel Seaview; in the western region aboard 77-ft chartered research vessel Island C. In both areas, sampling took place on the main vessel and aboard a 16-ft inflatable skiff. Acoustic transects were conducted aboard both the main vessel and the skiff.

Where possible, acoustic backscatter was sampled using a small midwater trawl (20 X 20-ft opening), hand jigging, and an underwater video camera. A small beam trawl (10-ft footrope) was used at several of the sites to sample bottom fishes. A 30-ft beach seine and 150-ft purse seine were used to sample very nearshore areas from the skiff.

A number of captured fishes were saved for analyses of diet and energy content. Oceanographic instruments were deployed to measure temperature, salinity, zooplankton abundance, and chlorophyll and nutrient concentrations at stations within each site. Identical oceanographic stations and fish sampling sites were visited in each season.

The last survey finished on 28 October, so results from the surveys are not yet available. However, below are a few general impressions from the survey efforts:

  1. Pacific herring appear to be the most abundant and ubiquitous forage fish species in both regions of the GOA.
     
  2. Chum and pink salmon fry were common throughout both regions during the spring, but absent in other seasons.
     
  3. During the summer and fall cruises researchers encountered large numbers of young-of-the-year (YOY) saffron cod, Pacific cod, and walleye pollock in various habitats.
     
  4. In summer and fall, nearshore water temperatures appeared to be consistently several degrees colder in the western region than in the eastern region.
     
  5. The beach seining activities demonstrated that there is an abundance of brown bears in most of the bays that line the Gulf of Alaska coastline.

By Olav Ormseth
 

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