NOAA Technical Memorandum NMFS-AFSC-229 

Diet of Nineteen Mesopelagic Fishes 

in the Gulf of Alaska 

by 

M-S. Yang 

U.S. DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 

Alaska Fisheries Science Center 

November 2011 
NOAA Technical Memorandum NMFS 

The National Marine Fisheries Service's Alaska Fisheries Science Center 

uses the NOAA Technical Memorandum series to issue informal scientific and 

technical publications when complete formal review and editorial processing 

are not appropriate or feasible. Documents within this series reflect sound 

professional work and may be referenced in the formal scientific and technical 

literature. 

The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries 

Science Center continues the NMFS-F/NWC series established in 1970 by the 

Northwest Fisheries Center. The NMFS-NWFSC series is currently used by 

the Northwest Fisheries Science Center. 

This document should be cited as follows: 

Yang, M-S. 2011. Diet of nineteen mesopelagic fishes in the Gulf of 

Alaska. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-229, 

67 p. 

Reference in this document to trade names does not imply endorsement by 

the National Marine Fisheries Service, NOAA. 
NOAA Technical Memorandum NMFS-AFSC-229 

Diet of Nineteen Mesopelagic Fishes 

in the Gulf of Alaska 

by 

M-S. Yang 

Alaska Fisheries Science Center 

7600 Sand Point Way N.E. 

Seattle, WA 98115 

www.afsc.noaa.gov

U.S. DEPARTMENT OF COMMERCE

 John E. Bryson, Secretary 

National Oceanic and Atmospheric Administration

 Jane Lubchenco, Under Secretary and Administrator 

National Marine Fisheries Service 

Eric C. Schwaab, Assistant Administrator for Fisheries 

November 2011 
This document is available to the public through: 

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, VA 22161 

www.ntis.gov 
ABSTRACT 

A total of 1,607 stomachs from 19 species were analyzed to describe the food habits of 

the mesopelagic fishes in the Gulf of Alaska in 2007. Longfin dragonfish (Tactostoma 

macropus), Pacific viperfish (Chauliodus macouni), scaly wearyfish (Scopelosaurus adleri), 

Alaska dreamer (Oneirodes thompsoni), and northern pearleye (Benthalbella dentata) were the 

main piscivores observed. Myctophids were the dominant prey fish. Garnet lampfish 

(Stenobrachius nannochir), bigeye lanternfish (Protomyctophum thompsoni), 

brokenline lanternfish (Lampanyctus jordani), highsnout bigscale (Melamphaes lugubris), 

shining tubeshoulder (Sagamichthys abei), and northern lampfish (Stenobrachius leucopsarus), 

fed mainly on calanoid copepods. Blue lanternfish (Tarletonbeania crenularis) and bluethroat 

argentine (Nansenia candida), fed mainly on larvaceans. California headlightfish (Diaphus 

theta), northern smoothtongue (Leuroglossus schmidti), Bathylagidae, and crested bigscale 

(Poromitra curilensis) ate different combinations of larvacean, euphausiids, calanoids, ostracods, 

gastropods, and chaetognaths. Pinpoint lampfish (Nannobrachium regale) consumed large 

amounts of shrimp and cephalopods. Barreleye (Macropinna microstoma) fed only on jellyfish. 

iii 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CONTENTS
 

ABSTRACT ................................................................. iii
 

INTRODUCTION ............................................................. 1
 

METHODS .................................................................. 2
 

Stomach Collection and Stomach Contents Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
 

Data Analysis ........................................................... 3
 

RESULTS and DISCUSSION .................................................... 4
 

Northern Lampfish ....................................................... 4
 

Garnet Lampfish ........................................................ 5
 

Pinpoint Lampfish ....................................................... 7
 

California Headlightfish ................................................... 8
 

Bigeye Lanternfish ....................................................... 9
 

Brokenline Lanternfish .................................................. 10
 

Blue Lanternfish ........................................................ 11
 

Highsnout Bigscale ..................................................... 11
 

Crested Bigscale ........................................................ 13
 

Shining Tubeshoulder ................................................... 14
 

Bluethroat Argentine .................................................... 14
 

Northern Smoothtongue .................................................. 15
 

Bathylagidae ........................................................... 16
 

Northern Pearleye ....................................................... 17
 

Pacific Viperfish ....................................................... 18
 

Scaly Wearyfish ........................................................ 19
 

Longfin Dragonfish ..................................................... 20
 

Alaska Dreamer ........................................................ 21
 

Barreleye ............................................................. 21
 

Important Prey of Mesopelagic Fish ........................................ 22
 

Diet Overlap ........................................................... 23
 

ACKNOWLEDGMENTS ...................................................... 25
 

CITATIONS ................................................................. 27
 

v 

 
INTRODUCTION

Mesopelagic (200 – 1,000 m depth) fishes include lanternfish (Myctophidae), deep-sea 

smelts (Bathylagidae), bigscale (Melamphaidae), viperfish (Stomiidae), spookfish 

(Opisthoproctidae), longfin dragon (Stomiidae), pearleye (Scopelarchidae), tubeshoulder 

(Platytroctidae), and anglerfish (Oneirodidae). They may have unusual adaptations to life in 

deepwater such as luminescent organs (photophores), fangs, anglers on their heads, or barrel eyes.

They are usually less than 15 cm long and have no commercial value. Therefore, little attention 

has been focused on them. However, they are an important part of marine ecosystems (Sinclair 

and Stabeno 2002, Uchikawa et al. 2008, Raring and Stevenson 2010), and they play an 

important role as food for many marine fishes (Yang et al. 2006), seabirds (Vermeer and Devito 

1988), and marine mammals (Kajimura and Loughlin 1988, Zeppelin and Ream 2006). They are, 

in turn, the primary consumers of zooplankton, euphausiids, larval, and juvenile fishes, and 

squids (Beamish et al. 1999). Sinclair and Stabeno (2002) pointed out that the nekton of the 

mesopelagic zone played an important role in the transport and redistribution of the organic 

matter from the rich surface waters to the benthos in the oceans. The total biomass of 

mesopelagic fishes appears to be large relative to the total catches of other fish in the same areas 

(Beamish et al. 1999).

Global warming and the ice retreat in the Arctic area may create dramatic changes of the 

ecosystem. The large biomass of mesopelagic fishes present there may eventually attract

commercial interest. Therefore, it is important to learn more about the biology and ecology of 

mesopelagic fishes and their relationships with other species. 
2 

 Most studies about the mesopelagic fishes in the North Pacific have focused on myctophids, 

primarily Stenobrachius leucopsarus, Stenobrachius nannochir, Lampanyctus jordani, and 

Diaphus theta in the western North Pacific (Moku et al. 2000, Sassa and Kawaguchi 2005, 

Uchikawa et al. 2008) and Bering Sea (Balanov 1994). However, little is known of the diets of 

the mesopelagic fishes in the Gulf of Alaska. The objective of this study is to compare the diets 

of 19 mesopelagic species in the Gulf of Alaska. Diet variations at different depths and diel 

variations are also discussed. 

METHODS

Stomach Collection and Stomach Contents Analysis

 In 2007, scientists from the Alaska Fisheries Science Center (AFSC) conducted a 

mesopelagic survey on board the NOAA ship Miller Freeman in the central Gulf of 

Alaska. The study was conducted from 31 March to 6 April in the area along the 1,500 m 

isobath between the eastern edge of Kodiak Island and the eastern edge of Prince William 

Sound (Fig. 1). 

 The sampling gear for the mesopelagic survey was a 30/26 Aleutian wing trawl 

equipped with a 1.2 cm stretched-mesh liner in the codend. The headrope and footrope 

each measured 81.7 m. Mesh size tapered from 3.25 m stretched-mesh at the forward end 

of the trawl to 0.1 m forward of the codend. The net was spread using 5 m2

, 1,247-kg 

steel doors. Midwater trawl tows were performed at six stations (Fig. 1) and targeted the 

250 m, 500 m, and 1,000 m depth at each station. Day (1000 – 1800 ADT) and night 

(2200 – 0600) tows at each depth in each station were executed. The net was towed at a 

constant speed of 3 knots for 30 minutes. Because the net used was not designed for 
3 

discrete depth sampling, specimens from a given haul may not have been caught at the 

target depth. However, every effort was made to minimize sample contamination by 

deploying and retrieving the net as quickly as possible (Raring and Stevenson 2010). 

 After retrieving the trawl, the catch was sorted to species, counted, and weighed.

For each species, 15 whole fish specimens were put in a large muslin or plastic bag along 

with a label indicating vessel, cruise, haul, species name, and number collected. The bags 

were then put in a 5 gallon bucket with 10% buffered formalin solution. 

 When the whole fish specimens arrived in the laboratory, they were transferred into 

70% ethanol before the stomach contents were analyzed. Stomachs were excised in the 

lab. Each stomach was cut open; the contents were removed and gently blotted with a 

paper towel. The wet weight was recorded to the nearest 0.001 g. After obtaining the total 

weight for a stomach’s contents, the contents were placed in a Petri dish and examined 

under a microscope. Each prey item was classified to the lowest practical taxonomic level. 

The prey items were weighed and enumerated whenever possible. If the prey items were 

too small (e.g., less than 0.001 g) to be weighed, the percent volume of these prey items 

was visually estimated and then converted to prey weights. Standard lengths of prey 

fishes were recorded.

Data Analysis 

 The general diet of each species was analyzed to show the percent frequency of 

occurrence and the percent total weight of each prey item in the stomach. Diet variations 

(percent weight) within each species were analyzed by each of the three depths (250 m, 
4 

500 m, and 1,000 m) and each of the two towing-modes (day-tow and night-tow), when 

data were available. Diet overlaps were analyzed among all the species.

RESULTS and DISCUSSION

Northern Lampfish

 Northern lampfish (Stenobrachius leucopsarus) and its congener, the garnet lampfish (S. 

nannochir), are morphologically similar species, but the northern lampfish is much more 

abundant in the Gulf of Alaska area (Raring and Stevenson 2010).

 Of the 210 specimens collected in 14 hauls, 110 had food in their stomachs and 100 had

empty stomachs. Specimens were collected from 250 m to 1,052 m depth. The average fork 

length (FL) for specimens with food was 10.1 + 0.93 cm (range 7.0 – 12.0 cm). Calanoid 

copepods comprised the highest amount (53%) of the total stomach contents weight (Table 1a), 

while Pleuromamma sp. was the most frequently occurring (32%) prey species. Other prey items

included euphausiids (36%), ostracods (3%), chaetognaths (1%), and larvaceans (1%).

 Table 1b lists the prey items of the northern lampfish collected at different depths (250 m, 

500 m, or 1,000 m) and at different times (day or night). At the 250 m depth, no stomachs were 

collected during daytime, whereas 47% of the stomachs collected at night were empty. At 500 m 

52% and 56% of stomach were empty, in day and night samples, respectively. In 1,000 m depth 

samples, northern lampfish had less empty stomachs in night collections (33%) than day 

collections (67%). This is probably because northern lampfish fed more at night. Euphausiids 

were only found in the northern lampfish stomachs collected at night at the 500 m and 1,000 m 

depths tows. 
5 

 Moku et al. (2000) noted that northern lampfish (in the western North Pacific) fed mainly 

on euphausiids, Neocalanus sp., and amphipods. Sobolevskii and Senchenko (1996) also found 

that northern lampfish (in eastern Kamchatka) fed mainly on euphausiids (87% by weight), 

copepods (7%), and amphipods (5%). 

 Northern lampfish and garnet lampfish are congeneric species; however, the diets of these 

two species were quite different. The main difference in diets between northern lampfish and 

garnet lampfish (see detailed description below) was the lack of euphausiids in the stomachs of 

garnet lampfish. This is because garnet lampfish did not migrate to the shallower depths at night 

and euphausiids were only found in the stomachs of northern lampfish collected at night. 

Garnet Lampfish

 Garnet lampfish (Stenobrachius nannochir) and its congeneric species, the northern 

lampfish (S. leucopsarus) are morphologically similar species. They both occurred in the western 

North Pacific, Kurile-Kamchatka area, Bering Sea, and Gulf of Alaska (Pearcy et al. 1979). 

However, the northern lampfish is much more abundant in the Gulf of Alaska (Raring and 

Stevenson 2010).

 A total of 28 garnet lampfish specimens were collected from five hauls. Nine specimens

had food in their stomachs and 19 were empty. Specimens were collected from four hauls that 

were deeper than 750 m and one haul that was 488 m. The average fork length for the fish with 

food was 11.3 + 0.71 cm (range 10.0 – 12.0 cm). Neocalanus sp. comprised the majority by 

weight (74%) of the total stomach contents of garnet lampfish (Table 2a). Other prey items

included unknown calanoids (15%), Euchaeta sp. (9%), and ostracods (3%). 
6 

 No diet variations by depth or by time were found for S. nannochir collected from 500 m 

and 1,000 m. Calanoid copepods made up more than 95% of the total stomach contents of S. 

nannochir collected from either 500 m or 1,000 m deep, during the day or night (Table 2b). No 

empty stomachs were found in the 500 m depth collection. However, the sample size was too 

small (N=3) to verify this finding. In the 1,000 m depth, either in day-tow or night-tow, about 75% 

of the stomachs were empty. This is probably because the garnet lampfish did not migrate to 

shallower water to feed (Gorbatenko and Il'inskii 1992). 

 Balanov et al. (1994) found that, in the Bering Sea area, garnet lampfish fed mainly on 

calanoid copepods, euphausiids, and chaetognaths. Moku et al. (2000) found that copepods, 

including Neocalanus sp., Pleuromamma sp., and Metridia sp., were the most important food of 

garnet lampfish in the North Pacific. No euphausiids were found in S. nannochir, but euphausiids 

constituted 36% of the total stomach contents weight of S. leucopsarus. Gorbatenko and Il’inskii 

(1992) also did not find euphausiids in the stomachs of S. nannochir. They pointed out that S. 

nannochir did not migrate to the epipelagic layer (0-200 m) at night and usually stayed in the 

deeper area, whereas S. leucopsarus did migrate to the upper layer at night. Peden et al. (1985) 

found that hauls in northeastern North Pacific from below 500 m captured proportionally many 

more S. nannochir than S. leucopsarus. 

 The main difference between diets of garnet lampfish and northern lampfish was the lack 

of euphausiids in the stomachs of garnet lampfish since they don’t migrate to the upper water 

column at night. 
7 

Pinpoint Lampfish

 The pinpoint lampfish (Nannobrachium regale) has the smallest photophores within the 

Family Myctophidae; however, it is the largest myctophid in Alaska. It can reach a length of 20 

cm (from this study). In the Alaskan waters, pinpoint lampfish were found in the Bering Sea, 

Gulf of Alaska, and the Aleutian Islands (Mecklenburg et al. 2002). Out of the 160 specimens 

collected from 11 hauls, 26 specimens had food, and 134 were empty. The average fork length of 

the 26 specimens was 13.9 + 1.88 cm (range 10.0-18.0 cm). Shrimp (mainly Hymenodora 

frontalis) made up the highest amount (45%) of the total stomach contents weight (Table 3a).

Cephalopods (32%), mysids (9%), and fish (9%) were also important food of pinpoint lampfish. 

Neocalanus cristatus occurred most frequently (19%) in the stomachs of pinpoint lampfish, but 

they accounted for only 3% of the total stomach contents weight. 

A high proportion (> 80%) of pinpoint lampfish had empty stomach at all depths (either from 

day or night tows) (Table 3b). There were four specimens (all empty) collected from a night tow 

at 250 m deep (not shown in Table 3b). A high percentage (67%) of mysids was found in the 

stomachs collected during daytime at 500 m. Unidentified fish were found mainly in the 

stomachs collected during the nighttime at both 500 m and 1,000 m deep (46% and 5% of the 

total stomach contents weight, respectively). Shrimp were found in the stomachs of pinpoint 

lampfish collected from the 1,000 m depth, both during day and night tows (19% and 51%, 

respectively). Cephalopods were not found to occur frequently in the stomachs, but they 

comprised 31% of the total stomach contents weight of the specimens collected during the 

daytime tow from the 1,000 m depth. 
8 

 The diet of pinpoint lampfish has not been studied in many areas; however, Collard (1970)

reported a specimen from California that fed mainly on euphausiids. 

California Headlightfish

 

 The California headlightfish (Diaphus theta) is a small myctophid. The maximum length is 

about 10 cm FL (this study). Of the 206 specimens collected from 18 hauls, 192 had food, and 14 

were empty. The average length of specimens with food was 7.7 + 0.66 cm FL (range 6.0-10.0 

cm). Larvaceans comprised the highest amount (41%) of the total stomach contents weight 

(Table 4a). Calanoid copepods (19%), euphausiids (18%), pteropods (9%) and myctophid (5%) 

were also important prey of California headlightfish. California headlightfish had the most 

diverse prey items (50 different prey items in total) among the species studied, followed by 

bluethroat argentine (31 prey items), Poromitra curilensis (30 prey items), northern 

smoothtongue and Bathylagidae (each had 28 different prey items), bigeye lanternfish (25 prey 

items) and northern lampfish (24 prey items). 

 Moku et al. (2000) reported that California headlightfish, in the western North Pacific, fed 

mainly on euphausiids, copepods (mainly Metridia sp. and Neocalanus sp.) and amphipods. 

Sobolevskii and Senchenko (1996) also found that euphausiids (72% by weight) and hyperiids 

(19%) were important food of California headlightfish in the eastern Kamchatka. 

 Larvaceans made up a high percentage (about 45%) of the stomach contents of California 

headlightfish collected in the 250 m deep area (Table 4b). Euphausiids were a more important 

prey item for the fish collected at 500 m and 1,000 (especially at night tow) than at 250 m. The 

night-tow data shows that 7%, 12%, and 14% of the specimens collected in the 250 m, 500 m, 
9 

and 1,000 m depth, respectively had empty stomachs. The proportion of empty stomachs 

increased with depth. 

Bigeye Lanternfish

The bigeye lanternfish (Protomyctophum thompsoni) is a small myctophid (< 7 cm; Hart

1973). It occurs off Baja California, Oregon, and Washington, and in the Gulf of Alaska, Bering 

Sea, and Kuril-Kamchatka Islands (Hart 1973). In this study, 59 specimens were collected from 

nine hauls; 57 specimens had food and 2 were empty. The average length of specimens with food 

was 4.7 + 0.69 cm FL (range 3.0 – 6.0 cm). Calanoid copepods comprised the highest amount 

(72%) of the total stomach contents weight (Table 5a). Euphausiids (18%) and amphipods (9%) 

were also important prey of bigeye lanternfish. 

 More bigeye lanternfish were collected from day tows (52) than from night tows (7), and 

more were collected from the 250 m and 500 m than 1,000 m depths. Only one stomach with 

food was collected from the 1,000 m depth in a night tow (Table 5b). The diet of bigeye 

lanternfish did not vary much between 250 m and 500 m. Specimens captured at both depths 

consumed a large amount of calanoid copepods and some euphausiids. Calanoids were the only 

prey item found in the stomachs of bigeye lanternfish caught in the 1,000 m depth at night. 

However, the small sample size (N = 2) in the 1,000 m collection needs to be taken into account. 

 Sassa and Kawaguchi (2005) found that the most important prey for bigeye lanternfish 

larvae (< 7.9 mm) were nauplii and Oithona spp., which were replaced by calanoid copepodites 

and ostracods as bigeye lanternfish size increased. Watanabe et al. (1999) found the bigeye 

lanternfish was not a vertical migrator. 
10

Brokenline Lanternfish

 Brokenline lanternfish (Lampanyctus jordani) occurs across the North Pacific from Japan 

through the subarctic realm, and in the Okhotsk Sea, Aleutian Islands, and the Gulf of Alaska 

(Uchikawa et al. 2008, Mecklenburg et al. 2002).

 A total of nine specimens were collected: four (44%) were empty and five had food in their

stomachs. Because of the small sample size (9), all stomach contents data were combined for the 

diet analysis. The average length for the specimens with food was 11.2 + 0.84 cm FL with a 

range between 10 and 12 cm. About 62% of the total stomach contents weight comprised 

copepods, of which Neocalanus cristatus made up the highest percentage (36%) (Table 6a).

Primno macropa (hyperiid amphipod) constituted 29% of the diet of the fish. Ostracods were 

common prey and occurred in 60% of all brokenline lanternfish, but they accounted for only 4% 

of the total stomach contents weight. 

 

 No diet variations by depth and time were observed for the brokenline lanternfish since the 

sample sizes were too small (Table 6b). Uchikawa et al. (2008) found that, in the continental 

slope off the Tohoku area in northern Japan, Lampanyctus jordani fed mainly on crustaceans like 

copepods, amphipods, euphausiids, and decapods. 
11

Blue Lanternfish

 A total of three specimens of blue lanternfish (Tarletonbeania crenularis) were collected.

The fork lengths of all three blue lanternfish were 6 cm. The specimens were collected from one 

haul made at 250 m during a day tow on 2 April, 2007. Diet of these three blue lanternfish 

consisted of 91% (by weight) larvaceans, 3% calanoid copepods Metridia sp., 3% hyperiid 

amphipods, and 3% euphausiids (Table 7). Aughtry (1953) found that blue lanternfish around 

Pebble Beach, California, fed mainly on euphausiids. 

 Diet of blue lanternfish was very similar to that of blue argentine (see below). Larvaceans 

made up a high percentage of the total stomach contents weight of blue lanternfish and blue 

argentine (91% and 88%, respectively). 

Highsnout Bigscale

 There are two species of bigscale in the Gulf of Alaska; highsnout bigscale (Melamphaes 

lugubris) and crested bigscale1

 (Poromitra curilensis). The crested bigscale has been used in the 

past as the common name for Poromitra crassiceps in Alaskan waters. This species was recently 

identified as P. curilensis and it is believed that P. crassiceps is restricted to the Atlantic Ocean. 

In this study, we use the crested bigscale as the common name for the species, P. curilensis, 

found in the Gulf of Alaska. In general, highsnout bigscale is smaller than crested bigscale and 

the color is lighter. Highsnout bigscale reached a maximum size of 10 cm. 

_____________________

1 D.E. Stevenson, Alaska Fisheries Science Center, 7600 Sand Point Way NE., Seattle, WA 98115. Pers. commun., 

September 2010.
12

 There were 142 specimens of highsnout bigscale collected from 10 hauls: 141 specimens 

had food and only one was empty. The average length of the 141 specimens was 7.6 + 0.89 cm 

FL (range 5.0 – 10.0 cm). Calanoid copepods comprised the highest amount (60%) of the total 

stomach contents weight (Table 8a). Chaetognaths made up only 12% of the total stomach 

contents weight, but they were the most frequently occurring (53%) food item found in the 

stomach samples. Euphausiids (6%), ostracods (6%), mysids (5%), shrimps (4%, mainly 

Hymenodora sp.), amphipods (1%), and pelagic polychaetes (1%) were also the prey of 

highsnout bigscale. All but one haul for highsnout bigscale were collected during night time, and 

all but one haul of the night collections were from 500 m and 1,000 m depths. 

 Day-tow data were only collected from the 1,000 m depth. Calanoid copepods comprised 

60% of the total stomach contents weight (Table 8b). Night-tow data covered all three depths.

Calanoid copepods were also important food of highsnout bigscale collected from night-tows. 

However, chaetognaths constituted a high proportion (33%) of the stomach contents of the 

highsnout bigscale collected at the 250 m depth from night-tows (Table 8b). Euphausiids were 

mainly found in the stomachs of highsnout bigscale collected at night at 1,000 m. They 

comprised 9% of the total stomach contents weight of that group. Out of 142 specimens, only 

one stomach collected from the 1,000 m depth at night was empty; all of the rest had food in 

them. 

 Crested bigscale is a similar species to highsnout bigscale. However, their diets were quite 

different. High percentage (about 60%) of calanoid copepods was found in highsnout bigscale 

diet, whereas calanoid copepods made up only 12% of the crested bigscale diet. Instead, crested 
13

bigscale consumed relatively high percentages of larvaceans, chaetognaths, and fishes (15, 13, 

and 12%, respectively) (Table 12a). 

Crested Bigscale 

 Two species, crested bigscale (Poromitra curilensis) and highsnout bigscale (Melamphaes 

lugubris), of the family Melamphaidae were collected in the AFSC’s 2007 Gulf of Alaska 

mesopelagic survey. In general, the crested bigscale is larger than the highsnout bigscale. Crested 

bigscale reached a maximum 18 cm SL (Parin and Ebeling 1980). Out of 106 specimens 

collected from eight hauls, 54 had food in their stomachs and 52 were empty. The average length 

of the 54 specimens was 10.2 + 1.08 cm FL (range 8.0-12.0 cm). Larvaceans made up the 

greatest amount (15%) of the total stomach contents weight (Table 9a). Chaetognaths (13%), 

calanoid copepods (12%), polychaetes (9%), ostracods (9%), and pelagic salps (7%) were also 

important prey of crested bigscale. Unknown fish accounted for 12% of the total stomach 

contents weight, but they were not the common prey of the crested bigscale (they only occurred 

in 2% of the stomachs examined). Day-tow specimens were only collected from the 1,000 m 

depth. 

 Diet of the crested bigscale collected from this category included mainly ostracods (35%) 

and larvaceans (33%). At night, at both the 500 m and 1,000 m depths, diets were mainly 

zooplankton such as salps, chaetognaths, and larvaceans (Table 9b). No specimens were 

collected from the 250 m depth. Fitch and Lavenberg (1968) noted that small crustaceans were 

the most abundant food found in crested bigscale stomachs they sampled. 
14

Shining Tubeshoulder

 Shining tubeshoulders (Sagamichthys abei) have a tube-like projection pointing posteriorly 

just above the pectoral fin. They occur throughout the north Pacific Ocean (Fitch and Lavenberg 

1968). Of the 24 specimens collected in six hauls, 14 had food in their stomachs and 10 were 

empty (42%). The average length of the 14 specimens with food was 10.5 + 3.48 cm FL (range 

6.0-20.0 cm). Neocalanus sp. comprised the highest amount (48%) of the total stomach contents 

weight (Table 10a). Chaetognaths (27%), larvaceans (13%), and Pleuromamma sp. (5%) were 

also important prey of shining tubeshoulders. Fitch and Lavenberg (1968) found that shining 

tubeshoulder fed mainly on crustaceans. 

 Table 10b lists the prey items of the shining tubeshoulder collected at 500 m at different 

times (day or night). There were more empty stomachs collected during the night (56%) than the 

day (29%). Neocalanus sp. and chaetognaths comprised 84% of the diet of the shining 

tubeshoulder collected during the daytime, whereas larvacean made up the highest amount (75%) 

of the diet of the fish collected at night. One specimen with an empty gut was collected at the 

1,000 m depth (not listed in Table 10b). 

Bluethroat Argentine

 The bluethroat argentine (Nansenia candida) belongs to the Family Microstomatidae.

Microstomatidae and Bathylagidae, along with three other families, belong to the Suborder 

Argentinoidei. They are small (usually less than 30 cm), silvery fishes. The maximum length for 

bluethroat argentine is about 24 cm SL (Mecklenburg et al. 2002). In Alaskan waters, they are

found in the Bering Sea and Gulf of Alaska, although the catch records are rare (Mecklenburg 
15

et al. 2002). In this study, 84 specimens were collected from 11 hauls; 76 specimens had food 

and 8 were empty. The average length of the 76 specimens was 12.7 + 1.17 cm FL (range 10.0 - 

16.0 cm). Larvaceans made up the highest amount (89%) of the total stomach contents weight 

(Table 11a). Pteropods (4%) and euphausiids (2%) were also food of bluethroat argentine. 

 Bluethroat argentine specimens collected from different depths or times showed no large 

diet variations (Table 11b). Larvaceans were the dominant food (more than 82% by weight) of 

the bluethroat argentine. Less than 15% of the stomachs collected from 250 m and 500 m depth 

were empty; however, more empty stomachs (25%) were found in the sample collected at night 

at the 1,000 m depth. 

 Taylor (1967) reported that this species was taken by a midwater trawl off the Queen 

Charlotte Islands, British Columbia, but no diet information was included. Balanov and Fedorov 

(1996) also reported the occurrence of the bluethroat argentine in the Bering Sea, but they also 

did not provide diet data.

Northern Smoothtongue 

 The northern smoothtongue (Leuroglossus schmidti) belongs to the Family Bathylagidae 

(deepsea smelts). It has a pointed head, projecting lower jaw, and no teeth on the tongue. The 

maximum length is about 20 cm (Mecklenburg et al. 2002). Of the 130 specimens collected from 

13 hauls, 88 had food and 42 were empty. The average length of the 88 specimens was 15.5 +

1.01 cm FL (range 11.0-18.0 cm). Ostracods made up the highest amount (42%) of the total 

stomach contents weight (Table 12a). Larvaceans (36%), calanoid copepods (9%), and 

chaetognaths (6%) were also important food of northern smoothtongue. 
16

 Gorbatenko and Il'inskii (1992) found that northern smoothtongue in the Bering Sea area 

fed mainly on calanoid copepods (52% by weight), larvaceans (12%), euphausiids (7%), and 

chaetognaths (5%), whereas ostracods (contrary to our results) comprised only 1% of the total 

stomach contents weight. 

 

 Table 12b indicates that ostracods made up a high percentage of the stomach contents of 

northern smoothtongue collected at night, especially at the 250 m depth (63%). Larvaceans were 

the other important food of northern smoothtongue collected at all different depths. They 

comprised a high percentage (> 69%) of the stomach contents weight of the specimens collected 

during the day at the 500 m and 1,000 m depths. Empty stomachs comprised 34% and 32% of 

the specimens collected in the day and night, respectively. More empty stomachs occurred when 

the sampling depth increased. It is important to note the small (5) sample size of specimens 

collected at 1,000 m in the day time. 

 Balanov et al. (1994) noted that northern smoothtongue came into the epipelagic zone at 

night and fed intensively in the upper mesopelagic zone at night and during the day. 

Bathylagidae 

 Two dark bathylagid species, Pseudobathylagus milleri and Bathylagus pacificus, inhabit 

the Gulf of Alaska. They frequently occurred in the catch during the 2007 mesopelagic survey. 

We were not able to identify the specimens to the species taxonomic level; hence, we categorized 

them as unknown bathylagids in the Family Bathylagidae. 

 Out of 153 bathylagid specimens collected from 11 hauls, 71 had food in the stomachs, and 

82 were empty. These bathylagids were mainly collected from the area deeper than 485 m and 
17

only one haul was 250 m. The average length for the fish with food was 13.8 + 2.75 cm FL

(range 5.0-18.0 cm). Larvaceans comprised the highest amount (25%) of the total stomach 

contents weight of bathylagids (Table 13a). Other prey included calanoid copepods (19%),

euphausiids (13%), amphipods (7%), and ostracods (5%). Fish and unknown mollusks (9% by 

weight, respectively) were also found in bathylagid stomachs, but they occurred less frequently 

in the stomachs (only 1% for each).

 Larvacean were important (> 30% by weight) food of bathylagids in the area between 

250 m and 500 m in both day and night tows (Table 13b). Diet of bathylagids at the 1,000 m 

depth varied greatly depending on the collecting time. During the daytime, the diet included 34% 

mollusks, 35% cephalopods, and 19% calanoids. However, at night, the diet included 23% 

euphausiids, 16% larvaceans, and 16% amphipods, respectively. Empty stomachs increased as 

the sampling depth increased during the night tows. Empty stomachs were found in 20%, 47%, 

and 56% of the specimens collected at night from the depths 250 m, 500 m, and 1,000 m, 

respectively.

 Balanov et al. (1994) found that Bathylagus pacificus fed mainly on jellyfish (24%), 

copepods (3%), and amphipods (3%) in the Bering Sea. Sobolevskii and Senchenko (1996) noted 

that jellyfish comprised high percentages (48% and 86% by weight) of the stomach contents of 

Bathylagus pacificus and Pseudobathylagus milleri, respectively. Calanoid copepods (16%) were 

also important food of Bathylagus pacificus in their study.

Northern Pearleye

 The northern pearleye (Benthalbella dentata) is a small, compressed, elongate fish with 

large mouth and eyes with a glistening, pearly area on them. The maximum length is about 
18

28 cm total length (Mecklenburg et al. 2002). Out of the 121 specimens collected from eight

hauls, 11 specimens had food and 110 were empty. The average length of the 11 specimens was 

15.1 + 2.66 cm FL (range 10.0-19.0 cm). Prey fish (mainly Stenobrachius sp.) made up 67% of 

the total stomach contents weight of northern pearleye (Table 14a). Shrimp (Sergestes similis) 

comprised the second highest amount (28%). Calanoid copepods and euphausiids together 

comprised only 5% of the food of northern pearleye. 

 No northern pearleye were collected at the 250 m depth. In the other two depth strata (500 

m and 1,000 m), empty stomachs constituted more than 85% of the samples, respectively (Table 

14b). Northern pearleye consumed a high percentage (>98%) of prey fish during the night tow 

(both in the 500 m and 1,000 m depth), whereas the fish collected during the day (at 500 m deep) 

consumed a high percentage (51%) of shrimp (Sergestes similis). Nevertheless, we need to note 

that these results were based on relatively small numbers of specimens that had food in their 

stomachs.

Pacific Viperfish

 The Pacific viperfish (Chauliodus macouni) has a slender body. It can be recognized by the 

fanglike teeth on the jaws. The maximum size of Pacific viperfish is 27 cm SL. In Alaskan 

waters, they were found in Bering Sea, Gulf of Alaska, and the Aleutian Islands (Mecklenburg et 

al., 2002). Out of the 118 specimens collected from 7 hauls, 16 specimens had food and 102 

were empty. The average length of the 16 specimens was 15.9 + 2.87 cm FL (range 12.0-20.0 

cm). The diet of Pacific viperfish was exclusively fish (Table 15a). Myctophids were the most 

important prey fish of Pacific viperfish, making up 67% of the total stomach contents weight. 

One 24 mm (SL) northern lampfish (Stenobrachius leucopsarus) was found in the stomach of a 
19

13 cm (FL) specimen. Other fish consumed by Pacific viperfish included one 91 mm (SL) 

slender fangjaw (Sigmops gracilis). It was consumed by one 18 cm (FL) specimen.

 Table 15b lists the prey items found in Pacific viperfish stomachs collected at different 

depths and time. In general, a high percentage (>80%) of empty stomachs were found in samples 

collected from all depths and times. No major diet variations of the Pacific viperfish were found 

between the specimens collected at different depths or times. They all fed mainly on fish, 

including myctophids and slender fangjaw (Table 15b). 

 Sobolevskii and Senchenko (1996) noted that Pacific viperfish was caught mostly in the 

deeper water of the mesopelagic area in daylight, and actively migrated to the upper water in the 

evening and late night. The migration might be related to feeding, but they did not provide any 

diet information in that study. Balanov (1994) found that, in the southwestern Bering Sea, fish 

(mainly myctophids and bathylagids) comprised 86-93% of the total stomach contents weight of 

Pacific viperfish, depending on the size of the predator. 

Scaly Wearyfish

 There are two valid species in the genus Scopelosaurus: Scopelosaurus harryi and 

Scopelosaurus adleri (Balanov and Saviniykh 1999). Specimens collected from the 2007 

mesopelagic survey in the Gulf of Alaska were all S. adleri. 

 A total of 19 specimens of scaly wearyfish were collected from four hauls. No empty 

stomachs were found in these 19 specimens. The average length of the specimens was 21.37 +

2.65 cm FL (range 19.0-30.0 cm). Chaetognaths were the most frequent (63%) prey of S. adleri; 

however, they comprised only 2% of the total stomach contents weight (Table 16a). Calanoid 

copepods comprised 3% of the stomach contents weight. Pacific viperfish (91% by weight) and 
20

northern lampfish (1% by weight) were the prey fish consumed by S. adleri. The Pacific 

viperfish (109 mm SL) was consumed by a 30 cm scaly wearyfish, and the northern lampfish 

(23 mm SL) was consumed by a 21 cm specimen. 

 We collected 17 specimens with food from the 500 m depth (at night) and only two 

specimens with food from the 1,000 m depth (also at night) (Table 16b). In the 500 m sample, 

jellyfish, calanoid copepods, euphausiids, and chaetognaths comprised 94% of the total stomach 

contents weight, whereas northern lampfish comprised 6% of the diet weight. In the 1,000 m 

sample, Pacific viperfish comprised 50% of the total stomach contents weight. 

 

 Fitch and Lavenberg (1968), based on the size of the mouth, assumed that adult S. harryi

fed on small fish and the younger fish fed on crustaceans. Il'inskiy et al. (1995) found that, in the 

southern Bering Sea, calanoid copepods (Neocalanus cristatus) and euphausiids (Thysanoessa 

longipes) were the most abundant food of S. harryi. Many calanoid copepod species and 

Thysanoessa spinifera were also found in the diet of scaly wearyfish in my study. Balanov (1994) 

reported that S. adleri, in the southwestern Bering Sea, fed mainly on Stenobrachius sp. They 

comprised 70% and 99% of the total stomach contents weight of S. adleri for fish size 20-25 cm 

and 25-30 cm, respectively. 

Longfin Dragonfish 

 Longfin dragonfish (Tactostoma macropus) have a very elongate body with numerous large 

teeth in both jaws. They can reach up to 41 cm. A total of 10 specimens of longfin dragonfish 

were collected from three hauls. Two specimens (19 and 22 cm fork length) had food in their 

stomachs and eight were empty. Nine of the specimens were collected from the 500 m deep day

tow. Seven of the nine fish had empty stomachs (77%). Fish (probably myctophids) was the only 
21

prey item found in the stomachs of the two fish collected from a day-tow at a depth of 481 m on 

1 April 2007. Fisher and Pearcy (1983) found that, on the Oregon continental slope, smaller 

specimens of longfin dragonfish (51 to 150 mm) fed mainly on euphausiids, and larger 

specimens (> 200 mm) fed mainly on myctophids and shrimp. Il'inskiy et al. (1995) also found 

that myctophids (Stenobrachius leucopsarus) were food of longfin dragonfish. 

Alaska Dreamer

 Three specimens of Alaska dreamer (Oneirodes thompsoni) were collected in this study,

one from the 500 m depth during a night tow and the other two from the 1,000 m depth at night. 

The Alaska dreamer has an average length of 8 + 2.83 cm FL with a range between 6 and 10 cm. 

One of the specimens collected from the 1,000 m depth had an empty stomach. Unknown teleost 

was the food of the specimen collected from the 500 m depth and squid was the food of the 

Alaska dreamer collected from the 1,000 m depth at night. Fitch and Lavenberg (1968) found 

that this species fed heavily on crustaceans in the California deep water. 

Barreleye

 A total of 22 barreleye (Macropinna microstoma) specimens were collected from five hauls.

Three specimens had food in the stomachs and 19 were empty. The specimens with food were 

collected from the 500 m deep water during the day. Of the empty stomachs, 3 were collected 

from the 500 m depth during the night, 14 were collected from the 500 m day tow, and 2 were 

collected from the 1000 m depth night tow. Because of the small sample sizes, it is not clear if 

there is any diel feeding behavior. The average length of the three barreleye with food was 10.67 

+ 3.21 cm (range 7.0-13.0 cm). Jellyfish was the only food found in barreleye in this study.
22

Robison and Reisenbichler (2008) noted that barreleyes are some of the few fish known to eat 

these gelatinous midwater animals. 

Important Prey of Mesopelagic Fish

 A total of 1,607 stomachs from 19 species were analyzed to describe the food habits of 

mesopelagic species in the Gulf of Alaska in 2007. The total number of stomachs analyzed and 

the main prey or prey groups of each species are summarized in Table 17. 

 In this study, 708 out of 1,607 stomachs were empty (44%). Many piscivores, like northern 

pearleye, Pacific viperfish, and longfin dragonfish had a high percentage (> 80%) of empty 

stomachs, whereas some planktivores like bigeye lanternfish, highsnout bigscale, bluethroat 

argentine, and California headlightfish had fewer empty stomachs (< 10%). All specimens in this 

study were collected in early spring (from 1 April to 4 April). The high percentage of empty 

stomachs found in the fish eaters might have something to do with regurgitation of the fish. It 

was hard to detect the regurgitation of the mesopelagic fish since most of them were in bad shape

when they were brought up to the surface from the deep water. We found many photophores on 

myctophids were lost, especially from fish from deeper waters (500-1,000 m).

 Longfin dragonfish, Pacific viperfish, Scopelosaurus adleri, northern pearleye, and Alaska 

dreamer were the main predators in the mesopelagic area in the Gulf of Alaska that consumed 

fish (> 65% by weight). Northern lampfish, garnet lampfish, bigeye lanternfish, brokenline 

lanternfish, highsnout bigscale, and shining tubeshoulder fed mainly on calanoid copepods 

(> 50% by weight). Blue lanternfish and bluethroat argentine fed mainly on larvaceans (> 88% 

by weight). California headlightfish, northern smoothtongue, Bathylagidae, and crested bigscale 

(Poromitra curilensis) can be categorized in a group that ate different combinations of 
23

larvaceans, euphausiids, calanoids, ostracods, gastropods, and chaetognaths. Pinpoint lampfish 

seemed not to belong to any of the other groups since they consumed high amounts of shrimp 

and cephalopods (45% and 32%, respectively). Barreleye also did not belong to any other groups.

Their only food was jellyfish.

Diet Overlap

 There were 13 main prey items or prey groups: jellyfish, polychaetes, gastropods, 

cephalopods, ostracods, calanoids, mysids, amphipods, euphausiids, shrimp, chaetognaths, 

larvaceans, and miscellaneous fishes. 

 The percent similarity index (PSI) was calculated by using the proportions of the prey items 

in the stomachs (values in Table 17) to show diet overlap between the mesopelagic species in the 

Gulf of Alaska. 

 The upper diagonal section in Figure 2 shows the percent similarity values between 

different mesopelagic species. The lower diagonal section shows diet overlap between species by 

categorizing the percent similarities into low (< 34%), medium (34-66%), and high (> 66%) 

levels of dietary overlap.

 Three main groups showed medium to high diet overlap (Fig. 2). On the right side of the 

figure, high (> 66%) diet overlap values were among longfin dragonfish (TM), Pacific viperfish

(CM), Scopelosaurus adleri (SC), Alaska dreamer (OT), and northern pearleye (BD) since a high 

percentage of fish were found in their diets. The highest overlap values (> 90%) were among 

longfin dragonfish, Pacific viperfish, and Scopelosaurus adleri. 
24

 On the left side of Figure 2, the overlap values among northern lampfish (SL), garnet 

lampfish (SN), bigeye lanternfish (PT), brokenline lanternfish (LJ), highsnout bigscale (ML), 

and shining tubeshoulder (SA) were either medium (34-66%) or high (> 66%) since they fed 

mainly on calanoids. The highest diet overlap value (76%) was between northern lampfish and 

bigeye lanternfish, followed by garnet lampfish and bigeye lanternfish (74%). 

 The diet overlap values between the species in the middle of Figure 2 were mainly medium 

(34-66%) or low (< 34%). Those species included blue lanternfish (TC), bluethroat argentine 

(NC), California headlightfish (DT), the unknown bathylagid (UB), crested bigscale (PC), 

northern smoothtongue (LS), and pinpoint lampfish (NR). Within this middle area, only two 

overlap values were high; they were 92% between blue lanternfish (TC) and bluethroat argentine 

(NC), and 78% between California headlightfish (DT) and Bathylagidae (UB).

All other diet overlap values between the fish eaters (on the right side of Fig. 2) and the 

calanoid feeders (on the left side of Fig. 2) were mainly low (white or blank cells in Fig. 2).
25

ACKNOWLEDGMENTS

 I would like to thank Nancy Roberson, Elaina Jorgensen, Duane Stevenson, and Nate 

Raring for collecting the mesopelagic fish specimens on board the Miller Freeman. Thanks also 

extend to Jeff Cordell who helped me identify many of the zooplankton found in the stomach

samples. I also want to thank Duane Stevenson, Tom Wilderbuer, Kerim Aydin, Christine Baier 

and James Lee for reviewing the manuscript. 

27

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Table 1a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Stenobrachius leucopsarus (northern lampfish) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Conchoecia sp. (ostracod) 19.09 3.46

Calanoida (copepod) 50.91 22.81

Neocalanus sp. (copepod) 3.64 1.84

Neocalanus cristatus (copepod) 2.73 2.30

Eucalanidae (copepod) 1.82 1.38

Eucalanus sp. (copepod) 8.18 3.00

Eucalanus bungii (copepod) 3.64 3.23

Euchaeta sp. (copepod) 4.55 2.07

Euchaeta elongata (copepod) 1.82 2.53

Metridiidae (copepod) 1.82 0.46

Metridia sp. (copepod) 4.55 0.92

Pleuromamma sp. (copepod) 31.82 9.22

Pleuromamma scutullata 1.82 0.69

Heterorhabdus sp. (copepod) 3.64 1.84

Heterorhabdus tanneri (copepod) 0.91 0.46

Mysidae (mysid) 0.91 0.92

Parandania boecki (amphipod) 0.91 2.30

Hyperiidea (amphipod) 2.73 1.61

Euphausiacea (euphausiid) 2.73 5.30

Thysanoessa sp. (euphausiid) 0.91 13.13

Thysanoessa spinifera (euphausiid) 0.91 17.97

Chaetognatha (arrow worm) 2.73 0.69

Copelata (larvacea) 2.73 1.15

Teleostei (fish) 0.91 0.69

Total non-empty stomachs = 110

Total prey number = 207

Total prey weight = 0.434 g

Total empty stomachs = 100

Number of hauls = 14

31
Table 1b . -- Prey items (expressed in percent total weight) of Stenobrachius leucopsarus (northern lampfish)

 collected in different depths in the Gulf of Alaska 2007 mesopelagic survey. 

 Day, day-tow; Night, night-tow.

 Day Night

Prey items 500 m 1,000 m Total 250 m 500 m 1,000 m Total

Conchoecia sp. 5.7 0.0 4.5 14.1 6.4 3.4 6.8

Calanoida unidentified 33.0 36.4 33.7 14.8 19.8 38.3 26.9

Neocalanus sp. 9.1 18.2 10.9 0.0 0.0 0.0 0.0

Neocalanus cristatus 11.1 0.0 8.9 0.0 1.1 3.6 2.0

Eucalanus bungii 0.0 0.0 0.0 31.2 0.0 14.9 13.6

Euchaeta sp. 3.6 0.0 2.9 9.5 5.6 0.0 4.0

Euchaeta elongata 7.1 0.0 5.7 0.0 0.0 1.1 0.5

Metridia sp. 4.5 9.1 5.4 3.3 0.4 0.0 0.9

Pleuromamma sp. 10.8 18.2 12.3 12.9 7.5 17.9 13.3

Heterorhabdus sp. 6.9 0.0 5.5 0.0 1.6 1.1 1.0

Mysid 0.0 0.0 0.0 9.5 0.0 0.0 2.1

Amphipoda 0.0 0.0 0.0 0.0 0.0 5.6 2.5

Hyperiidea 3.6 0.0 2.9 0.0 1.2 1.7 1.2

Thysanoessa sp. 0.0 0.0 0.0 0.0 52.7 11.2 22.6

Chaetognatha 2.9 9.1 4.1 0.0 0.0 0.0 0.0

Larvacean 1.8 9.1 3.3 4.8 0.0 0.0 1.1

Teleostei 0.0 0.0 0.0 0.0 3.7 1.1 1.2

Stomach with food 29 5 34 16 20 40 76

Empty stomachs 31 10 41 14 25 20 59

Total stomachs 60 15 75 30 45 60 135

% of empty stomachs 52 67 55 47 56 33 44

Number of hauls 4 1 5 2 3 4 9

Average of fork length 10.2 10.8 10.3 9.8 9.8 10.0 9.9

Minimum fork length 8 10 8 7 7 7 7

Maximum fork length 11 12 12 11 11 11 11

SD of fork length 0.25 0.84 0.24 0.55 0.69 0.45 0.49

32
Table 2a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Stenobrachius nannochir (garnet lampfish) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Conchoecia sp. (ostracod) 11.11 2.94

Calanoida (copepod) 44.44 14.71

Neocalanus sp. (copepod) 33.33 73.53

Euchaeta sp. (copepod) 11.11 8.82

Total non-empty stomachs = 9

Total prey number = 10

Total prey weight = 0.034 g

Total empty stomachs = 19

Number of hauls = 5

33
Table 2b. -- Prey items (expressed in percent total weight) of Stenobrachius nannochir 

 (garnet lampfish) collected in different depths in the Gulf of Alaska 2007

 mesopelagic survey. Day, day-tow; Night, night-tow.

Day Night

Prey items 500 m 1,000 m Total 1,000 m

Conchoecia sp. 4.2 0 2.1 0.0

Neocalanus sp. 95.8 100 97.9 0.0

Unknown calanoid 0.0 0 0.0 83.3

Euchaeta sp. 0.0 0 0.0 16.7

Stomach with food 3 1 4 5

Empty stomachs 0 3 3 16

Total stomachs 3 4 7 21

% of empty stomachs 0 75 43 76

Number of hauls 1 1 2 3

Average fork length 11.0 12.0 11.5 11.4

Minimum fork length 10 12 10 11

Maximum fork length 12 12 12 12

SD of fork length 1.00 0.00 0.96 0.55

34
Table 3a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Nannobrachium regale (pinpoint lampfish) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Cephalopoda (squid and octopus) 3.85 0.03

Teuthida (squid) 3.85 31.58

Crustacea 3.85 0.1

Conchoecia sp. (Ostracoda) 7.69 0.1

Calanoida (copepod) 3.85 0.42

Neocalanus sp. (copepod) 7.69 1.32

Neocalanus cristatus (copepod) 19.23 1.16

Eucalanus sp. (copepod) 3.85 0.06

Gaidius sp. (copepod) 3.85 0.13

Gnathophausia gigas (mysid) 3.85 5.84

Eucopia grimaldii (mysid) 3.85 2.74

Amphipoda (amphipod) 3.85 0.74

Primno macropa (amphipod) 3.85 0.1

Euphausiacea (euphausiid) 7.69 1.45

Hymenodora frontalis (shrimp) 7.69 20.63

Hippolytidae (shrimp) 3.85 13.24

Eualus pusiolus (shrimp) 3.85 11.43

Teleostei (fish) 11.54 8.91

Total non-empty stomachs = 26

Total prey number = 29

Total prey weight = 3.097 g

Total empty stomachs = 134

Number of hauls = 11

35
Table 3b. -- Prey items (expressed in percent total weight) of Nannobrachium regale (pinpoint lampfish)

 collected in different depths in the Gulf of Alaska 2007 mesopelagic survey. 

 Day, day-tow; Night, night-tow.

Day Night

Prey items 500 m 1,000 m Total 500 m 1,000 m Total

Cephalopod 0.2 30.6 12.3 0.0 0.0 0.0

Conchoecia sp. 0.0 0.1 0.1 0.0 1.5 0.9

Unknown calanoid 0.0 0.0 0.0 0.0 0.5 0.3

Neocalanus sp. 31.7 0.0 19.0 0.0 4.4 2.6

Neocalanus cristatus 0.0 35.7 14.3 10.4 0.4 4.4

Gaidius sp. 0.0 0.0 0.0 0.0 1.8 1.1

Neognathophausia gigas 66.5 0.0 39.9 0.0 0.0 0.0

Eucopia grimaldii 0.0 0.0 0.0 0.0 31.5 18.9

Amphipoda 0.0 0.0 0.0 15.3 0.0 6.1

Euphausiacea 1.6 0.0 1.0 28.7 0.0 11.5

Hymenodora frontalis 0.0 19.4 7.8 0.0 27.5 16.5

Hippolytidae 0.0 0.0 0.0 0.0 14.6 8.8

Eualus pusiolus 0.0 0.0 0.0 0.0 12.6 7.6

Teleostei 0.0 14.3 5.7 45.7 5.3 21.4

Stomach with food 4 5 9 6 9 15

Empty stomachs 16 25 41 39 37 76

Total stomachs 20 30 50 45 46 91

% of empty stomachs 80 83 82 87 80 84

Number of hauls 3 2 5 3 3 6

Average fork length 15.3 13.6 14.3 15.0 13.3 14.0

Minimum fork length 12 12 12 14 11 11

Maximum fork length 18 15 18 17 15 17

SD of fork length 2.75 1.52 2.18 1.1 1.32 1.46

36
Table 4a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Diaphus theta (California headlightfish) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Tomopteridae (polychaete) 0.52 0.02

Gastropoda (snail) 1.04 0.05

Pteropoda (pteropod) 2.08 0.48

Thecosomata (pteropod) 4.17 1.91

Limacina sp. (pteropod) 0.52 0.02

Limacina helicina (pteropod) 14.58 6.97

Clione limacina (pteropod) 0.52 0.02

Cephalopoda (squid and octopus) 0.52 0.01

Crustacea 0.52 0.1

Ostracoda 3.65 0.46

Myodocopa (ostracod) 0.52 0.03

Cypridina sp. (ostracod) 1.04 0.06

Conchoecia sp. (ostracod) 38.54 2.31

Calanoida (copepod) 31.25 3.1

Calanus sp. (copepod) 2.6 0.06

Calanus marshallae (copepod) 2.08 0.1

Neocalanus sp. (copepod) 18.75 1.99

Neocalanus cristatus (copepod) 4.17 0.32

Eucalanidae (copepod) 6.25 0.87

Eucalanus sp. (copepod) 21.88 2.05

Eucalanus bungii (copepod) 4.69 0.62

Gaetanus sp. (copepod) 1.56 0.05

Gaidius sp. (copepod) 7.29 0.26

Euchaeta sp. (copepod) 8.33 0.69

Euchaeta elongata (copepod) 2.6 0.3

Metridiidae (copepod) 1.56 0.11

Metridia sp. (copepod) 39.06 3

Pleuromamma sp. (copepod) 46.88 4.55

Pleuromamma scutullata (copepod) 3.65 0.32

Centropages sp. (copepod) 0.52 0.01

Lucicutia sp. (copepod) 0.52 0.02

Heterorhabdus sp. (copepod) 12.5 0.66

Heterorhabdus tanneri (copepod) 0.52 0.03

Candacia sp. (copepod) 0.52 0.02

Candacia columbiae (copepod) 1.56 0.03

Tortanus discaudatus (copepod) 0.52 0.02

Amphipoda (amphipod) 0.52 0.08

Gammaridea (amphipod) 0.52 0.02

Hyperiidea (amphipod) 5.73 0.53

Phronima sp. (amphipod) 0.52 0.1

Primno macropa (amphipod) 1.04 0.24

Euphausiacea (euphausiid) 12.5 6.04

Thysanoessa sp. (euphausiid) 1.04 2.56

Thysanoessa inermis (euphausiid) 0.52 0.88

Thysanoessa inspinata (euphausiid) 0.52 1.75

Thysanoessa raschi (euphausiid) 1.56 1.25

Thysanoessa spinifera (euphausiid) 2.6 5.78

37
Table 4a.--Continued.

Prey items Frequency (%) Weight (%)

Natantia (shrimp) 0.52 0.02

Caridea (shrimp) 0.52 0.06

Chaetognatha (arrow worm) 15.63 3.65

Copelata (larvacea) 64.06 37.45

Oikopleura sp. (larvacea) 2.6 3.17

Teleostei (fish) 0.52 0.1

Myctophidae (lanternfish) 0.52 4.76

Total non-empty stomachs = 192

Total prey number = 1,253

Total prey weight = 6.241 g

Total empty stomachs = 14

Number of hauls = 18

38
Table 4b. -- Prey items (expressed in percent total weight) of Diaphus theta 

 (California headlightfish) collected in different depths in the Gulf of Alaska 2007 

 mesopelagic survey. Day, day-tow, Night, night-tow.

 Day Night

Prey items 250 m 500 m 1,000 m Total 250 m 500 m 1,000 m Total

Tomopteridae 0.2 0.0 0.0 0.1 0.0 0.0 0.0 0.0

Gastropoda 0.0 0.0 0.0 0.0 0.2 0.0 0.0 0.1

Pteropoda 0.0 0.4 0.3 0.2 0.0 0.1 0.9 0.4

Thecosomata 0.0 0.1 0.0 0.0 0.0 10.6 1.1 3.6

Limacina sp. 0.2 0.0 0.0 0.1 0.0 0.0 0.0 0.0

Limacina helicina 1.6 10.0 2.5 5.0 0.4 4.9 19.4 9.3

Clione limacina 0.0 0.2 0.0 0.1 0.0 0.0 0.0 0.0

Cephalopoda 0.0 0.2 0.0 0.1 0.0 0.0 0.0 0.0

Crustacea 0.0 0.0 0.0 0.0 0.0 0.0 0.4 0.2

Ostracoda 0.0 0.0 0.0 0.0 0.0 1.8 0.6 0.8

Myodocopa 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.1

Cypridina sp. 0.0 0.4 0.0 0.2 0.0 0.0 0.0 0.0

Conchoecia sp. 1.0 4.0 3.8 2.8 5.0 3.1 3.2 3.7

Calanoida 1.0 4.8 2.8 2.9 8.4 7.1 4.3 6.4

Calanus sp. 0.0 0.1 0.0 0.0 0.7 0.2 0.0 0.3

Calanus marshallae 0.3 0.4 0.0 0.3 0.0 0.0 0.0 0.0

Neocalanus sp. 2.0 2.9 4.3 2.9 1.9 0.6 0.9 1.1

Neocalanus cristatus 0.0 1.0 0.3 0.4 0.8 1.1 0.0 0.6

Pseudocalanus sp. 0.0 0.0 0.0 0.0 0.0 0.2 0.0 0.1

Eucalanidae 0.0 0.0 5.1 1.3 0.0 1.0 1.0 0.7

Eucalanus sp. 11.2 1.5 0.0 4.8 3.5 0.0 0.9 1.4

Eucalanus bungii 0.0 1.6 0.8 0.8 0.3 0.0 1.3 0.6

Gaetanus sp. 0.1 0.1 0.0 0.1 0.5 0.0 0.0 0.2

Gaidius sp. 0.3 0.8 0.2 0.5 1.6 0.0 0.0 0.5

Euchaeta sp. 0.5 0.4 2.0 0.9 1.2 1.8 0.6 1.2

Euchaeta elongata 2.1 0.2 0.0 0.9 0.2 0.0 0.9 0.4

Metridiidae 0.0 0.0 0.0 0.0 0.0 0.4 0.0 0.1

Metridia sp. 5.1 3.9 1.3 3.7 6.2 1.1 0.5 2.4

Pleuromamma sp. 1.9 3.3 11.4 4.8 11.9 3.6 5.2 6.7

Pleuromamma scutullata 0.0 2.0 0.0 0.8 0.0 0.0 0.0 0.0

Centropages sp. 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Lucicutia sp. 0.0 0.0 0.3 0.1 0.0 0.0 0.0 0.0

Heterorhabdus sp. 0.6 1.0 1.5 1.0 1.5 0.2 0.8 0.8

Heterorhabdus tanneri 0.0 0.0 0.0 0.0 0.8 0.0 0.0 0.2

Candacia sp. 0.0 0.2 0.0 0.1 0.0 0.0 0.0 0.0

Candacia columbiae 0.0 0.1 0.0 0.0 0.1 0.4 0.0 0.1

Tortanus discaudatus 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0

Amphipoda 0.0 0.0 0.0 0.0 1.3 0.0 0.0 0.4

Gammaridea 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Hyperiidea 0.2 0.0 0.0 0.1 0.4 0.8 1.5 1.0

Phronima sp. 0.0 0.0 1.0 0.3 0.0 0.0 0.0 0.0

Primno macropa 2.8 0.0 0.0 1.1 0.0 0.0 0.0 0.0

Euphausiacea 1.1 12.4 1.3 5.4 0.6 2.8 15.9 7.4

Thysanoessa sp. 0.0 0.0 0.0 0.0 5.3 4.1 0.0 2.8

Thysanoessa inermis 0.0 4.8 0.0 1.8 0.0 0.0 0.0 0.0

Thysanoessa inspinata 0.0 0.0 0.0 0.0 0.0 0.0 3.9 1.6

Thysanoessa raschi 0.0 0.0 0.0 0.0 0.4 4.1 1.3 1.9

Thysanoessa spinifera 0.0 0.0 6.2 1.5 0.0 8.5 9.0 6.1

39
Table 4b.--Continued.

 Day Night

Prey items 250 m 500 m 1,000 m Total 250 m 500 m 1,000 m Total

Natantia 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0

Caridea 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.1

Chaetognatha 22.4 8.1 8.9 13.7 1.6 0.3 1.4 1.1

Copelata (larvacea) 36.3 35.5 45.8 38.4 41.1 26.0 21.7 28.8

Oikopleura sp. 9.1 0.0 0.0 3.4 2.5 0.0 2.9 1.9

Teleostei 0.0 0.0 0.0 0.0 1.6 0.0 0.0 0.5

Myctophidae 0.0 0.0 0.0 0.0 0.0 15.3 0.0 4.6

Stomach with food 33 35 15 83 42 30 37 109

Empty stomachs 0 1 0 1 3 4 6 13

Total stomachs 33 36 15 84 45 34 43 122

% of empty stomachs 0 3 0 1 7 12 14 11

Number of hauls 3 3 2 8 3 3 4 10

Average fork length 7.8 7.9 7.6 7.8 7.7 7.6 7.6 7.6

Minimum fork length 7 7 7 7 7 7 6 6

Maximum fork length 10 10 9 10 10 9 9 10

SD of fork length 0.48 0.26 0.63 0.70 0.66 0.57 0.64 0.19

40
Table 5a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Protomyctophum thompsoni (bigeye lanternfish) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Crustacea 3.51 0.78

Cypridina sp. (ostracod) 1.75 0.19

Conchoecia sp. (ostracod) 12.28 0.58

Calanoida (copepod) 52.63 12.09

Calanus sp. (copepod) 1.75 0.01

Neocalanus sp. (copepod) 14.04 3.51

Eucalanus bungii (copepod) 5.26 0.78

Gaetanus sp. (copepod) 3.51 0.39

Gaidius sp. (copepod) 19.3 3.70

Euchaeta sp. (copepod) 14.04 5.07

Euchaeta elongata (copepod) 21.05 16.96

Metridia sp. (copepod) 26.32 22.61

Pleuromamma sp. (copepod) 8.77 0.01

Pleuromamma scutullata (copepod) 1.75 0.39

Heterorhabdus sp. (copepod) 10.53 1.95

Heterorhabdus tanneri (copepod) 3.51 0.39

Candacia columbiae (copepod) 12.28 4.09

Epilabidocera sp. (copepod) 1.75 0.39

Hyperiidea (amphipod) 3.51 2.92

Primno sp. (amphipod) 5.26 2.34

Primno macropa (amphipod) 5.26 3.31

Euphausiacea (euphausiid) 5.26 5.85

Thysanoessa inspinata (euphausiid) 3.51 6.82

Thysanoessa raschi (euphausiid) 1.75 4.87

Chaetognatha (arrow worm) 3.51 0.01

Total non-empty stomachs = 57

Total prey number = 404

Total prey weight = 0.513 g

Total empty stomachs = 2

Number of hauls = 9

41
Table 5b. -- Prey items (expressed in percent total weight) of bigeye lanternfish 

 (Protomyctophum thompsoni ) collected in different depths in the Gulf of Alaska 2007

 mesopelagic survey. Day, day-tow; Night, night-tow.

Day Night

Prey items 250 m 500 m Total 500 m 1,000 m Total

Crustacea 0.0 0.0 0.0 50.0 0.0 33.3

Cypridina sp. 0.9 0.0 0.5 0.0 0.0 0.0

Conchoecia sp. 1.0 1.5 1.2 0.0 0.0 0.0

Calanoida 19.6 11.1 15.4 23.6 100.0 49.1

Calanus sp. 0.5 0.0 0.2 0.0 0.0 0.0

Neocalanus sp. 1.4 12.2 6.8 0.0 0.0 0.0

Eucalanus bungii 3.1 0.0 1.5 0.0 0.0 0.0

Gaetanus sp. 0.5 0.4 0.4 0.0 0.0 0.0

Gaidius sp. 3.8 1.8 2.8 2.8 0.0 1.9

Euchaeta sp. 1.0 24.7 12.8 0.0 0.0 0.0

Euchaeta elongata 17.3 6.5 11.9 0.0 0.0 0.0

Metridia sp. 20.9 3.2 12.1 0.0 0.0 0.0

Pleuromamma sp. 1.0 0.7 0.9 0.0 0.0 0.0

Pleuromamma scutullata 0.0 0.7 0.4 0.0 0.0 0.0

Heterorhabdus sp. 1.3 2.6 1.9 0.0 0.0 0.0

Heterorhabdus tanneri 0.0 1.1 0.5 0.0 0.0 0.0

Candacia columbiae 5.0 0.0 2.5 9.7 0.0 6.5

Epilabidocera sp. 0.3 0.0 0.1 0.0 0.0 0.0

Hyperiidea 0.0 7.5 3.7 0.0 0.0 0.0

Primno sp. 9.3 2.5 5.9 0.0 0.0 0.0

Primno macropa 1.5 2.9 2.2 0.0 0.0 0.0

Euphausiacea 0.0 8.0 4.0 13.9 0.0 9.3

Thysanoessa inspinata 11.8 0.0 5.9 0.0 0.0 0.0

Thysanoessa raschi 0.0 12.4 6.2 0.0 0.0 0.0

Chaetognatha 0.0 0.4 0.2 0.0 0.0 0.0

Stomach with food 39 13 52 4 1 5

Empty stomachs 0 0 0 1 1 2

Total stomachs 39 13 52 5 2 7

% of empty stomachs 0 0 0 20 50 29

Number of hauls 3 3 6 2 1 3

Average fork length 4.6 5.1 4.7 4.8 4.0 4.6

Minimum fork length 3 4 3 4 4 4

Maximum fork length 6 6 6 6 4 6

SD of fork length 0.64 0.64 0.67 0.96 0.00 0.89

42
Table 6a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Lampanyctus jordani (Brokenline lanternfish) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Crustacea 20.00 3.92

Conchoecia sp. (Ostracoda) 60.00 3.92

Calanoida (copepod) 20.00 13.73

Neocalanus cristatus (Copepoda) 20.00 36.25

Euchaeta sp. (Copepoda) 20.00 9.80

Pleuromamma sp. (Copepoda) 20.00 1.96

Primno macropa (amphipod) 20.00 29.41

Chaetognatha (arrow worm) 20.00 0.01

Total non-empty stomachs = 5

Total prey number = 11

Total prey weight = 0.051 g

Total empty stomachs = 4

Number of hauls = 5

43
Table 6b. -- Prey items (expressed in percent total weight) of Lampanyctus jordani (brokenline

 myctophid) collected in different depths in the Gulf of Alaska 2007 mesopelagic 

 survey. Day, day-tow; Night, night-tow.

Day Night

Prey items 500 m 500 m 1,000 m Total

Crustacea 0.0 0.0 100.0 25.0

Conchoecia sp . 22.2 6.7 0.0 5.0

Calanoida 77.8 33.3 0.0 25.0

Neocalanus cristatus 0.0 16.7 0.0 12.5

Euchaeta sp . 0.0 23.8 0.0 17.9

Pleuromamma sp . 0.0 4.8 0.0 3.6

Primno macropa 0.0 14.7 0.0 11.0

Chaetognatha 0.0 0.0 0.0 0.0

Stomach with food 1 3 1 4

Empty stomach 1 3 0 3

Total stomach 2 6 1 7

% of empty stomach 50.00 50 0 43

Number of hauls 1 3 1 4

Average fork length 11.0 11.3 11.0 11.3

Minimum fork length 11 11 11 10

Maximum fork length 11 12 11 12

SD of fork length 0.00 1.15 0.00 0.96

44
Table 7. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Tarletonbeania crenularis (blue lanternfish) collected in the Gulf of Alaska 2007

 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Metridia sp. (copepod) 33.33 2.94

Hyperiidea (amphipod) 33.33 2.94

Euphausiacea (euphausiid) 33.33 2.94

Copelata (larvacea) 100 91.18

Total non-empty stomachs = 3

Total prey number = 3

Total prey weight = 0.102 g

Total empty stomachs = 0

Number of hauls = 1

45
Table 8a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Melamphaes lugubris (highsnout bigscale) collected in the Gulf of Alaska

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Polychaeta (polychaete) 4.26 0.42

Tomopteris sp. (polychaete) 0.71 0.08

Spionidae (polychaete) 0.71 0.03

Cephalopoda (squid and octopus) 2.13 0.17

Crustacea 0.71 0.34

Ostracoda 3.55 0.34

Myodocopa (ostracoda) 0.71 0.03

Cypridina sp. 4.26 0.68

Conchoecia sp. 43.26 4.49

Calanoida (copepod) 43.97 20.15

Calanus sp. (copepod) 0.71 0.68

Calanus marshallae (copepod) 4.26 0.54

Calanus pacificus (copepod) 0.71 0.01

Neocalanus sp. (copepod) 31.91 15.52

Neocalanus cristatus (copepod) 31.21 14.05

Eucalanus sp. (copepod) 7.8 2.03

Eucalanus bungii (copepod) 4.96 0.96

Gaidius sp. (copepod) 2.84 0.08

Euchaeta sp. (copepod) 14.19 2.9

Euchaeta elongata (copepod) 7.8 2.09

Metridia sp. (copepod) 5.67 0.59

Pleuromamma sp. (copepod) 2.13 0.17

Pleuromamma scutullata (copepod) 0.71 0.03

Candacia sp. (copepod) 0.71 0.03

Eucopia sp. (mysid) 2.13 1.41

Eucopia unguiculata (mysid) 0.71 3.89

Mysida (mysid) 0.71 0.11

Amphipoda (amphipod) 0.71 0.06

Rhachotropis sp. (amphipod) 0.71 0.51

Hyperiidea (amphipod) 0.71 0.03

Primno macropa (amphipod) 0.71 0.71

Euphausiacea (euphausiid) 4.96 5.7

Thysanoessa spinifera (euphausiid) 0.71 0.59

Caridea (shrimp) 1.42 0.56

Hymenodora sp. (shrimp) 0.71 0.45

Hymenodora frontalis (shrimp) 2.84 2.68

Chaetognatha (arrow worm) 53.19 12.47

Thaliacea (pelagic salp) 0.71 0.2

Copelata (larvacea) 7.8 1.69

Unidentified organic material 1.42 2.54

Total non-empty stomachs = 141

Total prey number = 549

Total prey weight = 3.544 g

Total empty stomachs = 1

Number of hauls = 10

46
Table 8b. -- Prey items (expressed in percent total weight) of Melamphaes lugubris 

 (highsnout bigscale) collected in different depths in the Gulf of Alaska 2007 

 mesopelagic survey. Day, day-tow; Night, night-tow.

Day Night

Prey items 1,000 m 250 m 500 m 1,000 m Total

Polychaeta 1.1 0.0 0.2 1.0 0.6

Tomopteris sp. 0.0 0.0 0.3 0.0 0.1

Spionidae 0.0 0.4 0.0 0.0 0.0

Cephalopoda 0.0 0.0 0.1 0.2 0.2

Crustacea 0.0 0.0 0.8 0.0 0.3

Ostracoda 0.0 0.0 0.7 0.2 0.4

Myodocopa 0.0 0.0 0.1 0.0 0.1

Cypridina sp. 0.0 0.0 0.0 1.1 0.5

Conchoecia sp. 5.4 11.4 4.3 5.8 5.7

Calanoida 12.5 20.7 16.4 20.3 18.7

Calanus sp. 0.0 0.0 0.0 1.2 0.5

Calanus marshallae 0.0 0.0 0.0 1.1 0.5

Calanus pacificus 0.0 0.0 0.0 0.0 0.0

Neocalanus sp. 19.6 0.0 23.8 11.5 15.7

Neocalanus cristatus 23.9 14.0 17.3 10.0 13.7

Eucalanus sp. 0.0 10.0 0.1 8.2 4.8

Eucalanus bungii 0.0 0.0 0.4 1.6 0.8

Gaidius sp. 0.0 0.0 0.1 0.2 0.1

Euchaetidae 0.0 0.0 0.2 0.0 0.1

Euchaeta sp. 3.8 3.0 4.5 1.8 3.1

Euchaeta elongata 0.0 0.0 3.4 1.7 2.2

Metridia sp. 0.0 0.0 1.1 0.3 0.6

Pleuromamma sp. 0.0 0.0 0.1 0.2 0.1

Pleuromamma scutullata 0.0 0.0 0.0 0.0 0.0

Candacia sp. 0.0 0.0 0.0 0.1 0.0

Eucopia sp. 0.0 4.1 0.0 1.6 1.2

Eucopia unguiculata 0.0 0.0 0.0 5.4 2.4

Mysida 0.0 0.0 0.4 0.0 0.2

Amphipoda 0.0 0.0 0.2 0.0 0.1

Rhachotropis sp. 0.0 0.0 1.2 0.0 0.6

Hyperiidea 0.0 0.4 0.0 0.0 0.0

Primno macropa 0.0 0.0 2.1 0.0 0.9

Euphausiacea 1.1 0.0 3.4 8.8 5.4

Thysanoessa spinifera 0.0 0.0 1.4 0.0 0.6

Caridea 0.0 0.0 0.7 0.3 0.4

Hymenodora sp. 0.0 0.0 0.7 0.0 0.3

Hymenodora frontalis 15.2 0.0 1.4 3.3 2.1

Chaetognatha 8.2 32.5 12.5 9.8 13.5

Thaliacea 0.0 0.0 0.4 0.0 0.2

Larvacean 7.1 3.7 1.7 0.8 1.5

Unidentified organic material 2.2 0.0 0.0 3.4 1.5

Total empty stomachs = 1

Number of hauls = 10

47
Table 8b.--Continued.

Day Night

Prey items 1,000 m 250 m 500 m 1,000 m Total

Stomach with food 15 15 60 51 126

Empty stomachs 0 0 0 1 1

Total stomachs 15 15 60 52 127

% of empty stomachs 0 0 0 2 1

Number of hauls 1 1 4 4 9

Average fork length 8.1 6.5 7.8 7.6 7.6

Minimum fork length 7 5 6 6 5

Maximum fork length 9 9 10 10 10

SD of fork length 0.46 0.99 0.88 0.72 0.92

48
Table 9a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Poromitra curilensis (crested bigscale) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Polychaeta (polychaete) 11.11 5.54

Alciopidae (polychaete) 1.85 1.62

Tomopteridae (polychaete) 3.7 0.92

Tomopteris sp. (polychaete) 1.85 0.46

Mollusca 1.85 0.46

Gastropoda (snail) 3.7 2.31

Clione sp. (naked pteropod) 1.85 3.23

Cephalopoda (squid and octopus) 1.85 2.31

Crustacea 3.7 1.15

Ostracoda 3.7 2.08

Cypridina sp. (ostracod) 1.85 0.46

Conchoecia sp. (ostracod) 31.48 6.47

Calanoida (copepod) 5.56 1.85

Calanus sp. (copepod) 3.7 1.15

Calanus marshallae (copepod) 1.85 0.23

Neocalanus sp. (copepod) 1.85 1.39

Neocalanus cristatus (copepod) 1.85 0.69

Eucalanus sp. (copepod) 1.85 0.92

Eucalanus bungii (copepod) 1.85 1.39

Euchaeta elongata (copepod) 1.85 2.54

Metridia sp. (copepod) 7.41 2.31

Pseudolubbockia dilitata (cyclopoid) 1.85 0.46

Amphipoda (amphipod) 1.85 0.69

Hyperiidea (amphipod) 1.85 0.23

Chaetognatha (arrow worm) 5.56 12.93

Thaliacea (pelagic salp) 1.85 1.39

Salpa sp. (pelagic salp) 1.85 5.54

Copelata (larvacea) 11.11 15.47

Teleostei (fish) 1.85 11.55

Unidentified organic material 14.81 12.24

Total non-empty stomachs = 54

Total prey number = 105

Total prey weight = 0.433 g

Total empty stomachs = 52

Number of hauls = 7

49
Table 9b. -- Prey items (expressed in percent total weight) of Poromitra curilensis (crested bigscale)

 collected in different depths in the Gulf of Alaska 2007 mesopelagic survey. 

 Day, day-tow; Night, night-tow.

Day Night

Prey items 1,000 m 500 m 1,000 m Total

Polychaeta 7.3 2.2 3.1 3.0

Alciopidae 0.0 0.0 4.5 3.6

Tomopteridae 2.2 0.0 5.3 4.2

Tomopteris sp. 0.0 0.0 0.0 0.0

Mollusca 0.0 0.0 2.6 2.1

Gastropoda 0.0 0.0 6.4 5.1

Clione sp. 0.0 0.0 9.0 7.2

Cephalopoda 0.0 11.0 0.0 2.2

Crustacea 0.0 0.0 1.5 1.2

Ostracoda 0.0 0.0 3.3 2.6

Cypridina sp. 0.0 0.0 0.5 0.4

Conchoecia sp. 34.9 14.3 3.5 5.7

Calanoida 0.7 3.3 5.1 4.7

Calanus sp. 0.0 0.0 2.0 1.6

Calanus marshallae 6.3 0.0 0.0 0.0

Neocalanus sp. 0.0 0.0 7.9 6.3

Neocalanus cristatus 2.2 0.0 0.0 0.0

Eucalanus sp. 0.0 0.0 0.6 0.5

Eucalanus bungii 0.0 6.6 0.0 1.3

Euchaeta elongata 0.0 0.0 1.7 1.4

Metridia sp. 0.0 2.2 1.8 1.9

Pseudolubbockia dilitata 12.5 0.0 0.0 0.0

Amphipoda 0.0 0.0 1.5 1.2

Hyperiidea 0.7 0.0 0.0 0.0

Chaetognatha 0.0 0.0 8.6 6.9

Thaliacea 0.0 6.6 0.0 1.3

Salpa sp. 0.0 0.0 8.7 7.0

Larvacea 33.3 53.9 12.4 9.9

Teleostei 0.0 0.0 7.7 6.2

Unidentified organic material 0.0 0.0 2.5 12.7

Stomach with food 14 10 30 40

Empty stomachs 16 6 30 36

Total stomachs 30 16 60 76

% of empty stomachs 53 38 50 47

Number of hauls 2 1 4 5

Average fork length 10.2 10.6 10.1 10.2

Minimum fork length 9 9 8 8

Maximum fork length 12 12 12 12

SD of fork length 0.97 1.07 1.14 0.12

50
Table 10a. -- Prey items (expressed in percent frequency of occurrence and percent total weight)

 of Sagamichthys abei (shining tubeshoulder) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Crustacea 7.14 1.33

Cypridina sp. (ostracod) 7.14 1.33

Conchoecia sp. (ostracod) 7.14 1.33

Calanoida (copepod) 7.14 1.33

Neocalanus sp. (copepod) 14.29 48.00

Pleuromamma sp. (copepod) 21.43 5.33

Pleuromamma scutullata (copepod) 7.14 0.01

Heterorhabdus sp. (copepod) 7.14 1.33

Chaetognatha (arrow worm) 57.14 16.00

Sagitta sp. (arrow worm) 7.14 10.67

Copelata (larvacea) 42.86 13.33

Total non-empty stomachs = 14

Total prey number = 20

Total prey weight = 0.075 g

Total empty stomachs = 10

Number of hauls = 6

51
Table 10b. -- Prey items (expressed in percent total weight) of Sagamichthys abei 

 (shining tubeshoulder) collected in different depths in the Gulf of Alaska 2007 

 mesopelagic survey. Day, day-tow; Night, night-tow.

Day Night

Prey items 500 m 500 m

Crustacea 0.0 4.8

Cypridina sp. 0.6 0.0

Conchoecia sp. 0.0 9.5

Calanoida 3.3 0.0

Neocalanus sp. 21.1 0.0

Pleuromamma sp. 10.1 0.0

Pleuromamma scutullata 3.3 0.0

Heterorhabdus sp. 8.3 0.0

Chaetognatha 45.7 0.0

Sagitta sp. 4.7 0.0

Larvacea 2.9 85.7

Stomach with food 10 4

Empty stomachs 4 5

Total stomachs 14 9

% of empty stomachs 29 56

Number of hauls 3 3

Average fork length 9.9 12.0

Minimum fork length 6 8

Maximum fork length 13 20

SD of fork length 2.33 5.66

52
Table 11a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Nansenia candida (bluethroat argentine) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Polychaeta (polychaete) 2.63 0.28

Alciopidae (polychaete) 2.63 0.52

Tomopteridae (polychaete) 3.95 0.14

Tomopteris sp. (polychaete) 1.32 0.01

Gastropoda (snail) 2.63 0.14

Heteropod (snail) 1.32 1.15

Pteropoda (snail) 1.32 0.03

Thecosomata (shelled pteropod) 1.32 0.14

LImacina helicina (shelled pteropod) 14.47 0.69

Gymnosomata (naked pteropod) 7.89 1.07

Clione sp. (naked pteropod) 11.84 0.68

Clione limacina (naked pteropod) 10.53 1.37

Octopoda (octopus) 1.32 0.09

Conchoecia sp. (ostracod) 2.63 0.02

Calanoida (copepod) 1.32 0.02

Neocalanus sp. (copepod) 1.32 0.01

Neocalanus cristatus (copepod) 3.95 0.16

Euchaeta elongata (copepod) 2.63 0.06

Amphipoda (amphipod) 1.32 0.04

Gammaridea (amphipod) 1.32 0.01

Cyphocaris sp. (amphipod) 1.32 0.01

Hyperiidea (amphipod) 2.63 0.16

Hyperiidae (amphipod) 1.32 0.01

Euphausiacea (euphausiid) 6.58 0.67

Thysanoessa inermis (euphausiid) 3.95 0.41

Thysanoessa longipes (euphausiid) 1.32 0.24

Thysanoessa raschi (euphausiid) 1.32 0.25

Thysanoessa spinifera (euphausiid) 2.63 0.72

Copelata (larvacea) 48.68 35.72

Oikopleura sp. (larvacea) 47.37 52.96

Unidentified organic material 6.58 2.23

Total non-empty stomachs = 76

Total prey number = 105

Total prey weight = 16.981 g

Total empty stomachs = 8

Number of hauls = 11

53
Table 11b. -- Prey items (expressed in percent total weight) of Nansenia candida (bluethroat argentine)

 collected in different depths in the Gulf of Alaska 2007 mesopelagic survey. 

 Day, day-tow; Night, night-tow.

Day Night

Prey items 250 m 500 m Total 250 m 500 m 1,000 m Total

Polychaeta 0.0 0.6 0.5 0.7 0.0 0.0 0.2

Alciopidae 0.0 1.3 1.0 0.0 0.0 0.0 0.0

Tomopteridae 0.0 0.0 0.0 0.6 0.2 0.0 0.3

Tomopteris sp . 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Gastropoda 0.8 0.3 0.4 0.0 0.0 0.0 0.0

Heteropod 0.0 1.7 1.4 0.0 0.0 0.0 0.0

Pteropoda 0.0 0.0 0.0 0.3 0.0 0.0 0.1

Thecosomata 0.0 0.2 0.2 0.0 0.0 0.0 0.0

LImacina helicina 0.0 0.9 0.7 0.9 0.0 0.0 0.3

Gymnosomata 0.0 1.4 1.1 0.0 0.7 0.0 0.3

Clione sp. 0.0 0.8 0.7 0.0 1.7 18.3 3.9

Clione limacina 1.6 2.2 2.1 0.0 0.6 0.0 0.3

Octopoda 0.0 0.2 0.1 0.0 0.0 0.0 0.0

Conchoecia sp. 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Calanoida 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Neocalanus sp. 0.0 0.0 0.0 0.1 0.0 0.0 0.1

Neocalanus cristatus 0.0 0.0 0.0 1.0 0.8 0.0 0.7

Euchaeta elongata 0.0 0.1 0.1 0.6 0.0 0.0 0.2

Amphipoda 0.0 0.0 0.0 0.0 0.5 0.0 0.2

Gammaridea 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Cyphocaris sp. 0.2 0.0 0.1 0.0 0.0 0.0 0.0

Hyperiidea 0.0 0.0 0.1 0.0 0.7 0.0 0.3

Hyperiidae 0.0 0.0 0.0 0.0 0.2 0.0 0.1

Euphausiacea 0.0 1.0 0.8 0.0 0.0 0.0 0.0

Thysanoessa inermis 0.0 0.4 0.3 1.2 0.0 0.0 0.4

Thysanoessa longipes 0.0 0.2 0.1 0.0 0.0 0.0 0.0

Thysanoessa raschi 0.0 0.2 0.2 0.0 0.0 0.0 0.0

Thysanoessa spinifera 0.0 0.5 0.4 0.0 0.7 0.0 0.3

Larvacea 97.3 19.2 34.8 55.9 78.2 26.8 62.2

Oikopleura sp. 0.0 68.1 54.5 27.3 12.3 54.9 24.4

Unidentified organic material 0.0 0.5 0.4 11.5 3.4 0.0 5.5

Stomach with food 3 51 54 7 12 3 22

Empty stomachs 0 5 5 1 1 1 3

Total stomachs 3 56 59 8 13 4 25

% of empty stomachs 0 9 8 13 8 25 12

Number of hauls 1 4 5 2 3 1 6

Average fork length 13.0 12.8 12.8 11.9 13.0 12.0 12.5

Minimum fork length 12 11 11 10 10 10 10

Maximum fork length 14 16 16 14 16 14 16

SD of fork length 1.00 0.97 0.97 1.21 1.60 2.00 1.57

54
Table 12a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Leuroglossus schmidti (northern smoothtongue) collected in the Gulf of Alaska

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Gastropoda (snail) 1.14 0.15

Limacina helicina (pteropod) 1.14 0.67

Clione limacina (pteropod) 2.27 1.71

Myodocopa (ostracoda) 1.14 0.07

Cypridina sp. (ostracod) 6.82 4.98

Conchoecia sp. (ostracod) 56.82 37.3

Calanoida (copepod) 17.05 0.96

Calanus sp. (copepod) 2.27 0.22

Neocalanus sp. (copepod) 1.14 0.22

Eucalanus sp. (copepod) 3.41 0.59

Eucalanus bungii (copepod) 1.14 0.22

Gaidius sp. (copepod) 1.14 0.01

Euchaeta sp. (copepod) 1.14 0.15

Metridia sp. (copepod) 20.45 1.04

Pleuromamma sp. (copepod) 14.77 2.97

Pleuromamma scutullata (copepod) 7.95 2.15

Heterorhabdus tanneri (copepod) 1.14 0.07

Heterostylites major (copepod) 1.14 0.07

Amphipoda (amphipod) 5.68 0.37

Gammaridea (amphipod) 1.14 0.07

Cyphocaris sp. (amphipod) 2.27 0.52

Parandania boecki (amphipod) 1.14 0.45

Hyperiidea (amphipod) 1.14 0.01

Scina sp. (amphipod) 1.14 0.15

Euphausiacea (euphausiid) 3.41 1.78

Chaetognatha (arrow worm) 9.09 5.5

Copelata (larvacea) 57.95 35.74

Marine snow 9.09 1.86

Total non-empty stomachs = 88

Total prey number = 781

Total prey weight = 1.346 g

Total empty stomachs = 42

Number of hauls = 13

55
Table 12b. -- Prey items (expressed in percent total weight) of Leuroglossus schmidti 

 (northern smoothtongue) collected in different depths in the Gulf of Alaska 2007 

 mesopelagic survey. Day, day-tow; Night, night-tow.

Day Night

Prey items 500 m 1,000 m Total 250 m 500 m 1,000 m Total

Gastropoda 0.0 0.0 0.0 0.0 0.5 0.0 0.2

Limacina helicina 0.0 0.0 0.0 3.4 0.0 0.0 0.8

Clione limacina 0.0 0.0 0.0 0.0 5.8 0.0 2.0

Myodocopa 0.0 0.0 0.0 0.1 0.0 0.0 0.0

Cypridina sp. 0.0 0.0 0.0 8.5 2.0 1.1 3.0

Conchoecia sp. 3.0 6.3 3.8 63.0 28.4 13.4 29.4

Calanoida 0.0 0.0 0.0 1.0 2.9 1.7 1.9

Calanus sp. 0.0 0.0 0.0 0.0 0.0 3.5 1.6

Neocalanus sp. 0.9 0.0 0.7 0.0 0.0 0.0 0.0

Eucalanus sp. 1.8 0.0 1.4 1.6 0.0 0.0 0.4

Eucalanus bungii 0.0 0.0 0.0 0.0 0.0 0.5 0.2

Gaidius sp. 0.0 0.0 0.0 0.3 0.0 0.0 0.1

Euchaeta sp. 0.0 0.0 0.0 0.0 0.6 0.0 0.2

Metridia sp. 0.6 0.0 0.5 1.8 5.0 0.7 2.4

Pleuromamma sp. 3.1 0.0 2.3 2.7 6.2 0.4 2.8

Pleuromamma scutullata 0.0 0.0 0.0 0.0 15.2 8.8 9.0

Heterorhabdus tanneri 0.0 0.0 0.0 0.0 1.0 0.0 0.3

Heterostylites major 1.0 0.0 0.8 0.0 0.0 0.0 0.0

Amphipoda 0.0 0.0 0.0 0.0 1.5 2.5 1.6

Gammaridea 0.0 0.0 0.0 0.1 0.0 0.0 0.0

Cyphocaris sp. 0.0 0.0 0.0 0.7 0.0 1.1 0.6

Parandania boecki 1.6 0.0 1.2 0.0 0.0 0.0 0.0

Hyperiidea 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Scina sp. 0.0 0.0 0.0 0.0 0.4 0.0 0.1

Euphausiacea 0.0 0.0 0.0 0.7 0.0 5.5 2.6

Chaetognatha 1.2 0.0 0.9 0.7 8.1 19.5 11.5

Larvacea 84.4 68.8 80.5 10.8 22.6 41.5 28.4

Marine snow 2.4 25.0 8.0 4.7 0.0 0.0 1.0

Stomach with food 23 2 25 23 21 19 63

Empty stomachs 10 3 13 1 12 16 29

Total stomachs 33 5 38 24 33 35 92

% of empty stomachs 30 60 34 4 36 46 32

Number of hauls 3 1 4 2 3 4 9

Average fork length 15.6 17.0 15.7 15.2 15.6 15.5 15.4

Minimum fork length 11 17 11 13 14 14 13

Maximum fork length 18 17 18 17 16 16 17

SD of fork length 1.34 0 1.34 1.04 0.68 0.70 0.84

56
Table 13a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of unknown bathylagid collected in the Gulf of Alaska 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Polychaeta (polychaete) 1.41 1.33

Mollusca 1.41 9.66

Pteropoda 1.41 0.57

Cephalopoda (squid and octopus) 1.41 4.92

Cypridina sp. (ostracod) 2.82 0.76

Conchoecia sp. (ostracod) 30.99 4.55

Calanoida (copepod) 26.76 7.39

Neocalanus sp. (copepod) 2.82 1.33

Eucalanus bungii (copepod) 1.41 0.38

Gaidius sp. (copepod) 9.86 2.27

Euchaetidae (copepod) 1.41 0.19

Euchaeta sp. (copepod) 2.82 1.70

Metridiidae (copepod) 1.41 0.01

Metridia sp. (copepod) 11.27 1.52

Pleuromamma sp. (copepod) 9.86 1.33

Pleuromamma scutullata (copepod) 5.63 1.70

Heterorhabdus sp. (copepod) 4.23 1.14

Oncaea sp. (copepod) 1.41 0.01

Corycaeus sp. (copepod) 1.41 0.01

Amphipoda (amphipod) 4.23 6.82

Euphausiacea (euphausiid) 2.82 4.55

Euphausia pacifica (euphausiid) 1.41 1.70

Thysanoessa spinifera (euphausiid) 1.41 7.01

Chaetognatha (arrow worm) 1.41 0.57

Thaliacea (pelagic salp) 1.41 0.57

Copelata (larvacea) 28.17 24.62

Teleostei (fish) 1.41 8.52

Unidentified organic material 4.23 4.84

Total non-empty stomachs = 71

Total prey number = 123

Total prey weight = 0.528 g

Total empty stomachs = 82

Number of hauls = 11

57
Table 13b. -- Prey items (expressed in percent total weight) of unknown bathylagid collected in different

 depths in the Gulf of Alaska 2007 mesopelagic survey. Day, day-tow; Night, night-tow.

Day Night

Prey items 500 m 1,000 m Total 250 m 500 m 1,000 m Total

Polychaeta 0.0 0.0 0.0 0.0 2.5 0.0 0.9

Mollusca 0.0 33.6 22.4 0.0 0.0 0.0 0.0

Pteropoda 0.0 0.0 0.0 0.0 2.1 0.0 0.8

Cephalopoda 0.0 35.1 23.4 0.0 0.0 0.0 0.0

Cypridina sp. 0.0 0.0 0.0 0.0 0.0 1.5 0.8

Conchoecia sp. 0.0 8.1 5.4 17.0 3.2 4.2 5.4

Calanoida 0.0 9.3 6.2 7.6 11.6 7.9 9.3

Neocalanus sp. 0.0 0.0 0.0 0.0 0.0 4.3 2.1

Eucalanus bungii 0.0 0.0 0.0 0.0 0.0 0.6 0.3

Gaidius sp. 0.0 0.0 0.0 0.0 4.6 1.5 2.5

Euchaetidae 0.0 0.0 0.0 3.8 0.0 0.0 0.5

Euchaeta sp. 0.0 3.3 2.2 0.0 0.0 10.0 5.0

Metridiidae 0.0 0.0 0.0 0.0 0.7 0.0 0.3

Metridia sp. 0.0 2.7 1.8 0.0 1.1 4.5 2.6

Pleuromamma sp. 0.0 2.7 1.8 7.6 0.0 1.4 1.6

Pleuromamma scutullata 0.0 0.0 0.0 0.0 5.0 8.4 1.9

Heterorhabdus sp. 0.0 0.7 0.4 0.0 0.0 0.0 4.2

Oncaea sp. 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Corycaeus sp. 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Amphipoda 0.0 0.0 0.0 0.0 3.9 15.5 9.2

Euphausiacea 0.0 0.0 0.0 0.0 0.0 7.3 3.7

Euphausia pacifica 0.0 0.0 0.0 0.0 3.6 0.0 1.3

Thysanoessa spinifera 0.0 0.0 0.0 0.0 0.0 15.7 7.8

Chaetognatha 0.0 0.0 0.0 0.0 0.0 1.3 0.6

Thaliacea 0.0 0.0 0.0 0.0 1.4 0.0 0.5

Larvacea 100.0 0.0 33.3 64.2 30.6 16.0 27.5

Teleostei 0.0 0.0 0.0 0.0 16.3 0.0 6.1

Unidentified organic material 0.0 4.6 3.1 0.0 4.3 0.0 1.6

Marine snow 0.0 0.0 0.0 0.0 9.2 0.0 3.5

Stomach with food 2 11 13 8 24 26 58

Empty stomachs 7 18 25 2 21 33 56

Total stomachs 9 29 38 10 45 59 114

% of empty stomachs 78 62 66 20 47 56 50

Number of hauls 1 2 3 1 3 4 8

Average fork length 11.5 14.9 14.4 8.8 14.6 14.2 13.6

Minimum fork length 9 12 9 5 9 10 5

Maximum fork length 14 17 17 12 18 18 18

SD of fork length 3.54 1.51 2.14 2.38 1.86 2.26 2.87

58
Table 14a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Benthalbella dentata (northern pearleye) collected in the Gulf of Alaska

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Euchaeta elongata (copepod) 9.09 2.22

Thysanoessa sp. (euphausiid) 9.09 2.77

Sergestes similis (Pacific sergestid) 9.09 28.12

Teleostei (fish) 18.18 0.35

Myctophidae (lanternfish) 27.27 5.06

Stenobrachius sp. (lanternfish) 18.18 31.58

Stenobrachius leucopsarus (northern lampfish) 18.18 29.92

Total non-empty stomachs = 11

Total prey number = 19

Total prey weight = 1.444 g

Total empty stomachs = 110

Number of hauls = 8

59
Table 14b. -- Prey items (expressed in percent total weight) of Benthalbella dentata

 (northern pearleye) collected in different depths in the Gulf of Alaska 2007 

 mesopelagic survey. D, day-tow; N, night-tow.

Day Night

Prey items 500 m 500 m 1,000 m Total

Euchaeta elongata 14.5 0.0 0.0 0.0

Thysanoessa sp. 17.5 0.0 0.0 0.0

Sergestes similis 33.3 0.0 0.0 0.0

Teleostei 33.3 0.0 1.4 0.6

Myctophidae 1.3 0.0 48.6 19.4

Stenobrachius sp. 0.0 33.3 50.0 40.0

Stenobrachius leucopsarus 0.0 66.7 0.0 40.0

Stomach with food 4 3 4 7

Empty stomachs 47 41 22 63

Total stomachs 51 44 26 70

% of empty stomachs 92 93 85 90

Number of hauls 3 3 2 5

Average fork length 14.8 14.0 16.3 15.3

Minimum fork length 12 10 15 10

Maximum fork length 18 18 19 19

SD of fork length 2.75 4.00 1.89 2.93

60
Table 15a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Chauliodus macouni (Pacific viperfish) collected in the Gulf of Alaska 

 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Calanoida (copepod) 6.25 0.02

Teleostei (fish) 12.5 3.25

Sigmops gracilis (slender fangjaw) 6.25 30.06

Myctophidae (lanternfish) 31.25 3.02

Stenobrachius sp. (lanternfish) 37.5 60.65

Stenobrachius leucopsarus (northern lampfish) 6.25 3.00

Total non-empty stomachs = 16

Total prey number = 17

Total prey weight = 11.47 g

Total empty stomachs = 102

Number of hauls = 7

61
Table 15b. -- Prey items (expressed in percent total weight) of Chauliodus macouni

 (Pacific viperfish) collected in different depths in the Gulf of Alaska 2007 

 mesopelagic survey. Day, day-tow; Night, night-tow.

Day Night

Prey items 500 m 500 m 1,000 m Total

Calanoida 0.0 0.0 0.3 0.2

Teleostei 25.0 28.7 0.0 9.6

Sigmops gracilis 0.0 0.0 50.0 33.3

Myctophidae 25.0 71.3 30.2 43.9

Stenobrachius sp. 48.0 0.0 19.6 13.1

Stenobrachius leucopsarus 2.0 0.0 0.0 0.0

Stomach with food 8 3 5 8

Empty stomachs 47 12 40 52

Total stomachs 55 15 45 60

% of empty stomachs 85 80 89 86

Number of hauls 4 1 2 3

Average fork length 16.3 13.3 16.8 15.5

Minimum fork length 13 12 12 12

Maximum fork length 20 14 20 20

SD of fork length 2.49 1.15 3.63 3.34

62
Table 16a. -- Prey items (expressed in percent frequency of occurrence and percent total weight) 

 of Scopelosaurus adleri collected in the Gulf of Alaska 2007 mesopelagic survey.

Prey items Frequency (%) Weight (%)

Scyphozoa (jellyfish) 5.26 1.70

Calanoida (copepod) 15.79 0.69

Neocalanus cristatus (copepod) 10.53 0.25

Gaidius sp. (copepod) 5.26 0.02

Euchaeta sp. (copepod) 5.26 0.23

Euchaeta elongata (copepod) 26.32 1.42

Metridia sp. (copepod) 26.32 0.08

Pleuromamma sp. (copepod) 5.26 0.02

Heterorhabdus sp. ( copepod) 5.26 0.01

Thysanoessa spinifera (euphausiid) 5.26 1.94

Chaetognatha (arrow worm) 63.16 1.70

Chauliodus macouni (Pacific viperfish) 5.26 90.98

Stenobrachius leucopsarus (northern lampfish) 5.26 0.93

Total non-empty stomachs = 19

Total prey number = 76

Total prey weight = 8.094 g

Total empty stomachs = 0

Number of hauls = 4

63
Table 16b. -- Prey items (expressed in percent total weight) of Scopelosaurus adleri (scaly wearyfish)

 collected in different depths in the Gulf of Alaska 2007 mesopelagic survey.Night, night-tow. 

Night

Prey items 500 m 1,000 m Total

Syphozoa 11.8 0.0 5.9

Calanoida 32.1 0.0 16.1

Gaidius sp. 0.2 0.0 0.1

Euchaeta sp. 10.0 39.6 24.8

Metridia sp. 0.1 0.0 0.0

Pleuromamma sp. 0.2 0.0 0.1

Heterorhabdus sp. 0.1 0.0 0.0

Thysanoessa spinifera 13.4 0.0 6.7

Chaetognatha 25.8 10.4 18.1

Stenobrachius leucopsarus 6.4 0.0 3.2

Chauliodus macouni 0.0 50.0 25.0

Stomach with food 17 2 19

Empty stomachs 0 0 0

Total stomachs 17 2 10

% of empty stomachs 0 0 0

Number of hauls 2 2 4

Average fork length 20.9 25.5 21.4

Minimum fork length 19 21 19

Maximum fork length 26 30 30

SD of fork length 1.73 6.36 2.65

64
Table 17. -- Percent by weight of the important prey or prey group consumed by the mesopelagic fish in the Gulf of Alaska in 2007.

 AMP, amphipod; BD, Benthalbella dentata ; CAN, calanoids; CEP, cephalopod; CHA, chaetognath; CM, Chauliodus macouni ; 

 DT, Diaphus theta ; EUP, euphausiid; FIS, all fish; GAS, gastropod; JFH, jellyfish; LAR, larvacean; LJ, Lampanyctus jordani;

 LS, Leuroglossus schmidti ; ML, Melamphaes lugubris; MM, Macropinna microstoma ;MYS, mysid; NC, Nansenia candida ;

 NR, Nannobrachium regale; OST, ostracod; OT, Oneirodes thompsoni; PC, Poromitra curilensis; POL, polychaete; 

 PT, Protomyctophum thompsoni ; SA, Sagamichthys abei ; SC, Scopelosaurus adleri ; SHR, shrimp;

 SL, Stenobrachius leucopsarus; SN, Stenobrachius nannochir; TC, Tarletonbeania crenularis; TM, Tactostoma macropus;

 UB, unknown bathylagid.

 Predator

Prey MM SN PT LJ ML SA SL TC NC DT UB PC LS NR BD OT SC CM TM

JFH 100 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0

POL 0 0 0 0 1 0 0 0 1 <1 1 9 0 0 0 0 0 0 0

GAS 0 0 0 0 0 0 0 0 5 9 10 6 3 0 0 0 0 0 0

CEP 0 0 0 0 <1 0 0 0 <1 <1 5 2 0 32 0 25 0 0 0

OST 0 3 1 4 6 3 3 0 <1 3 5 9 42 <1 0 0 0 0 0

CAN 0 97 73 62 60 56 53 3 <1 21 19 12 7 3 2 0 2 <1 0

MYS 0 0 0 0 5 0 1 0 0 0 0 0 0 9 0 0 0 0 0

AMP 0 0 9 29 1 0 4 3 <1 1 7 1 2 1 0 0 0 0 0

EUP 0 0 17 0 6 0 36 3 2 18 13 0 2 1 3 0 2 0 0

SHR 0 0 0 0 4 0 0 0 0 <1 0 0 0 45 28 0 0 0 0

CHA 0 0 <1 <1 12 27 1 0 0 4 1 13 6 0 0 0 2 0 0

LAR 0 0 0 0 1 13 1 91 88 41 25 15 36 0 0 0 0 0 0

FIS 0 0 0 0 0 0 1 0 0 5 9 12 0 9 66 75 92 99 100

Total stomachs 22 28 59 9 142 24 210 3 84 206 153 106 130 160 121 3 19 118 10

Stomachs with food 3 9 57 5 141 14 110 3 76 192 71 54 88 26 11 2 19 16 2

Empty stomachs 19 17 2 4 1 10 100 0 8 14 52 52 42 134 110 1 0 102 8

% of empty 86 61 3 44 1 42 48 0 10 7 34 49 32 84 91 33 0 86 80

65
Figure 1.-- Collection locations (X) of specimens in the Gulf of Alaska in 2007 mesopelagic survey.

170.0 W 160.0 W 150.0 W

52.0 N

57.0 N

Alaska

Kodiak I.

Gulf of Alaska

Alaska Peninsula

Unimak I.

Akutan I.

Umnak I.

Unalaska I.

66
MM SN PT LJ ML SA SL TC NC DT UB PC LS NR BD OT SC CM TM

MM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0

SN 74 65 63 59 56 3 1 24 22 15 10 4 2 0 2 0 0

PT 69 69 58 76 9 4 41 41 15 13 6 5 0 5 1 0

LJ 66 60 61 6 3 26 31 18 14 5 2 0 3 1 0

ML 72 66 8 8 39 35 34 23 16 6 1 6 1 0

SA 58 16 2 41 38 29 29 4 2 0 4 1 0

SL 10 6 46 42 19 16 8 6 1 6 2 1

TC 92 53 34 19 43 5 5 0 4 1 0

NC 53 37 25 44 5 3 1 3 1 0

DT 78 48 56 13 11 6 11 6 5

UB 52 45 21 14 14 25 10 9

PC 41 16 14 14 16 13 12

LS 6 4 0 6 1 0

NR 40 34 12 10 9

BD 66 70 67 66

OT 75 75 75

SC 93 92

CM 99

TM

 <34 34-66 >66

Diet Overlap

 Low Medium High

Figure 2. -- Percent Similarity Index (%) of dietary overlap of the mesopelagic fish in the Gulf of Alaska.

 BD, Benthalbella dentata ; CM, Chauliodus macouni ; DT, Diaphus theta ; LJ, Lampanyctus jordani ; 

 L S, Leuroglossus schmidti ; ML, Melamphaes lugubris; MM, Macropinna microstoma ;

 NC, Nansenia candida ;NR, Nannobrachium regale; OT, Oneirodes thompsoni;

 PC, Poromitra curilensis; PT, Protomyctophum thompsoni ; SA, Sagamichthys abei ;

 SC, Scopelosaurus adleri ; SL, Stenobrachius leucopsarus; SN, Stenobrachius nannochir;

 TC, Tarletonbeania crenularis; TM, Tactostoma macropus;UB, unknown bathylagid.

67

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