||Eunice valens (Family Eunicidae)
Welcome to the Stomach Examiner's Tool (SET). Here, we present information
that is useful when performing stomach content analysis of marine fish
collected in Alaskan waters; the eastern Bering Sea, Gulf of Alaska, and Aleutian Islands. The
information provided here should also be helpful for analysts working on the food
habits of marine fish in the coastal waters of Washington, Oregon, and
Food Habits Laboratory of the Alaska Fisheries Science Center (AFSC) Resource
Ecology Ecosystem Modeling Program (REEM) has been collecting data on the food habits
of commercially and non-commercially important fish species since the early
1980s. Over the 30+ years of processing stomach contents, we have accumulated a wealth of
taxonomic information that is useful for identifying prey found in marine fish stomachs.
We have used a digital camera to record the distinguishing taxonomic features of
whole specimens, partially digested specimens, gill arches, vertebrae,
postcleithrum, otoliths, telson of crustaceans, subopercle and preopercle of
fish, setae of polychaetes, and other slow digesting hard parts. The objective of this
web site is to provide the comprehensive information as a guide for stomach
content analysts to identify the prey items in marine fish stomachs quickly and easily.
Prey images and data presented here include pelagic (water column) prey such as zooplankton, small forage fish, juvenile and adult groundfish and benthic prey (on the sea floor) prey such as shrimp, crab, juvenile and adult groundfish, marine worm, amphipods, clams and snails.
The Resource Ecology and Ecosystem Modeling (REEM) program at the Alaska Fisheries
Science Center has been collecting and processing stomachs of the marine
fish collected from the eastern Bering Sea (EBS), Gulf of Alaska (GOA), and
Aleutian Islands (AI) since 1983.
Diet data are used to describe feeding ecology and predator-prey relationships
and are used for mortality estimation, fishery management and ecosystem modeling. Therefore,
many researchers encounter situations where they need to get diet
data by processing fish stomachs.
During the past 30 years, many people have contributed to the collection of useful
taxonomic information (e.g., vertebrae, gill arches, otoliths of fish; pictures
of partially digested fish and invertebrates) for the identification of prey
of the marine fish.
This web-based, Stomach Examiner's Tool (SET) provides comprehensive
information as a guide for the stomach content examiner to identify the prey
items in the stomachs of the marine fish in the Alaska waters. This
online service will guide you to find the possible prey of a specific predator,
help you to distinguish the similar taxonomic species or groups, and how to
narrow down the scope of your unknown prey items. These data will be updated
routinely, when new information or new tools for the improvement of prey
identification are added.
The Trophic Interaction Program (Food Habits Lab) in the Resource
Ecology and Fishery Management (REFM) Division of the Northwest and Alaska
Fisheries Center (NWAFC) was created in 1983. Initially the program systematically collected fish stomach samples annually from the eastern Bering Sea, however stomach sampling was extended
to the Gulf of Alaska and Aleutian Islands in 1990 and 1991, respectively.
The NWAFC was split into Alaska Fisheries Science Center (AFSC) and
Northwest Fisheries Science Center (NWFSC) in the late 1980s. The Trophic
Interaction Program was subsequently renamed to Resource Ecology and Ecosystem Modeling
(REEM) program as part of AFSC.
Stomach samples of commercially important predator species, such as walleye pollock (Gadus
chalcogrammus), Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus
stenolepis), arrowtooth flounder (Atheresthes stomias), Kamchatka
flounder (Atheresthes evermanni), Greenland turbot (Reinhardtius
hippoglossoides) yellowfin sole (Pleuronectes asper), rock sole (Pleuronectes
bilineatus), flathead sole (Hippoglossoids elassodon), and Alaska
plaice (Pleuronectes quadrituberculatus), were the primary focus when the program began.
However, sample collections were expanded to ecologically important, non-commercial species, such as skates, osmerids, myctophids, bathylagids, rockfish, cottoids, zoarcids, and many others in the later years.
Generally, taxonomic guides use external physical characteristics to identify organisms.
However, due to the varying degree of the digestion seen in consumed prey items (from no digestion to partially
digested, to highly digested), we have had to develop alternative methods of prey identification.
We primarily depend on digestion resistant hard parts such as boney structures (e.g. vertebrae,
gill arches, subopercles, post cleithrum, otoliths), setae, jaws, and ossicles that remain in the stomachs to
identify the original prey. Over the past many years, we have collected both specimens and
photos of these diagnostic prey parts to help identify prey commonly found in North Pacific predators.
Our collection includes images of taxonomic
characteristics relevant to the identification of whole specimens, partially digested specimens,
gill arches, vertebrae, postcleithrum, otoliths, telson of crustaceans, subopercle and
preopercle of fish, and setae of polychaetes, etc. By making this information available
online, our colleagues, students, and anyone is interested in stomach content
analysis can quickly and easily access it.
Stomach Content Colleciton and Analysis
The Lab Manual (.pdf, 122KB) describes details of the stomach content analysis procedures used by the
Resource Ecology and Ecosystem Modeling program in Alaska Fisheries Science
Center. It covers sample preparation, recording predator and prey data,
quantitative stomach analysis, qualitative stomach analysis, prey size data,
and some special techniques used to identify prey.
Manuals describing at-sea fish stomach collection techniques, sample design and stratification are available on the REEM Manual page
There are many references to help with the identification of different prey from a variety of fish stomachs. Some important characteristics for distinguishing similar prey items (e.g. juvenile walleye pollock and capelin) are included in the comments of the specific prey species in the main categories (e.g. gill arch, vertebral column).
We thank many people who have been involved in this project over the past 30 years.
In the early days, Frank Morado and his Pathobiology lab let us use their digital camera
equipment for gill arch pictures, we thank them. Karna McKinney, with her
expertise in photography, gave us lessons and showed us the basics
of using Photoshop. Without her help, we would not be able to have this
accomplishment. Most of the Photoshop work was done by Kim Sawyer and
The Lab Manual (.pdf, 122KB)
was most recently contributed to by Troy Buckley, Geoff Lang, Mei-Sun Yang, Rick Hibpshman,
Caroline Robinson, Kim Sawyer, and Sean Rohan.
Jeff Cordell, at the University of Washington, has been identifying some
specimens for our lab and giving his taxonomic expertise during the past many
years. Morgan Busby, Ann Matarese, and Debbie Blood (FOCI) have been identifying
fish larvae and eggs for us. We appreciate their constant help.
Geoff Lang is our data manager and webmaster. He developed the data
base and created this web page for us.