NOAA Technical Memorandum NMFS-AFSC-142


Identification of Skates, Sculpins, and 

Smelts by Observers in North Pacific 

Groundfish Fisheries (2002-2003) 

by 

D. E. Stevenson

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 

Alaska Fisheries Science Center 

March 2004 
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 new NMFS-NWFSC series will be used by 

the Northwest Fisheries Science Center. 

This document should be cited as follows: 

Stevenson, D. E. 2004. Identification of skates, sculpins, and smelts 

by observers in North Pacific groundfish fisheries (2002-2003). U.S. 

Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-142, 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-142


Identification of Skates, Sculpins, and 

Smelts by Observers in North Pacific 

Groundfish Fisheries (2002-2003) 

by 

D. E. Stevenson

Alaska Fisheries Science Center 

7600 Sand Point Way N.E. 

Seattle, WA 98115 

www.afsc.noaa.gov 

U.S. DEPARTMENT OF COMMERCE

Donald L. Evans, Secretary 

National Oceanic and Atmospheric Administration 

Vice Admiral Conrad C. Lautenbacher, Jr., U.S. Navy (ret.), Under Secretary and Administrator 

National Marine Fisheries Service 

William T. Hogarth, Assistant Administrator for Fisheries 

March 2004 
This document is available to the public through: 

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Springfield, VA 22161 

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iii

ABSTRACT 

Recent emphasis on ecosystem-level management of federally regulated marine fisheries, 

as well as a rapidly developing skate fishery in the Gulf of Alaska, has led to an increasing need 

for basic population data for skates (Rajidae), sculpins (Cottidae and allied families), and forage 

fishes (e.g., Osmeridae, Clupeidae, and Ammodytidae). Observers in the North Pacific 

Groundfish Observer Program could provide a wealth of such data by routinely identifying these 

fishes to the species level. The objectives of this project were 1) to quantify the additional time

observers would require on a per-haul basis to complete species-level identifications of all skates 

and smelts, and genus-level identifications of selected sculpins; and 2) to develop and assess the 

adequacy of an introductory training presentation and a series of materials for use by observers 

in the field. 

Over 130 returning fisheries observers were trained to identify skates, smelts, and 

sculpins. Once deployed, participating observers established an alternating sampling scheme of 

control hauls and experimental hauls. Participants completed Species Identification forms for 

each new species encountered and recorded species composition data in the NORPAC database. 

After deployment, debriefers solicited comments and constructive feedback from participants 

and assessed the accuracy of field identifications. 

Participating observers required an average of 4.27 additional minutes per haul to 

complete the specific identifications. The time required was not dependent on the gear used or 

target of the fishery, but variation among observers and among hauls within cruise was 

substantial. The field identification resources and training presentation were constantly updated 

throughout this study to reflect participant feedback and new information. Participants were 

usually able to demonstrate confident knowledge of identifications during debriefings, and 
iv

geographic and bathymetric distributions obtained from study data generally did not conflict with 

published distributions or those obtained from bottom trawl survey data. Therefore, there were 

no indications of any widespread identification problems in this study. 
v

CONTENTS

 Page 

Abstract.......................................................................................................................................... iii 

Introduction......................................................................................................................................1 

Materials and Methods.....................................................................................................................2 

Results ..............................................................................................................................................4 

Table 1. Distribution of hauls used to calculate mean identification times...............................9 

Table 2. Mean identification time per haul for Project and Non-Project hauls.........................9 

Table 3. Number of hauls in which each taxon was encountered and total specimen counts.10 

Table 4. Number of hauls in which each taxon was encountered by gear type.......................11 

Figure 1. Average identification time per haul by gear type ...................................................12 

Figure 2. Average identification time per haul by target species ............................................12 

Figure 3. Average identification time per haul for first through twentieth Project haul .........13 

Figure 4. Seasonal distribution of sampling effort...................................................................13 

Figure 5. Geographic distribution of big skate (Raja binoculata) records..............................14 

Figure 6. Bathymetric distribution of big skate (Raja binoculata) records.............................14 

Figure 7. Geographic distribution of longnose skate (Raja rhina) records .............................15 

Figure 8. Bathymetric distribution of longnose skate (Raja rhina) records............................15 

Figure 9. Geographic distribution of Alaska skate (Bathyraja parmifera) records.................16 

Figure 10. Bathymetric distribution of Alaska skate (Bathyraja parmifera) records..............16 

Figure 11. Geographic distribution of Bering skate (Bathyraja interrupta) records...............17 

Figure 12. Bathymetric distribution of Bering skate (Bathyraja interrupta) records..............17 
vi

Figure 13. Geographic distribution of Aleutian skate (Bathyraja aleutica) records ...............18 

Figure 14. Bathymetric distribution of Aleutian skate (Bathyraja aleutica) records..............18 

Figure 15. Geographic distribution of whiteblotched skate (Bathyraja maculata) records ....19 

Figure 16. Bathymetric distribution of whiteblotched skate (Bathyraja maculata) records ...19 

Figure 17. Geographic distribution of Commander skate (Bathyraja lindbergi) records........20 

Figure 18. Bathymetric distribution of Commander skate (Bathyraja lindbergi) records ......20 

Figure 19. Geographic distribution of Okhotsk skate (Bathyraja violacea) records...............21 

Figure 20. Bathymetric distribution of Okhotsk skate (Bathyraja violacea) records..............21 

Figure 21. Geographic distribution of roughtail skate (Bathyraja trachura) records..............22 

Figure 22. Bathymetric distribution of roughtail skate (Bathyraja trachura) records ............22 

Figure 23. Geographic distribution of whitebrow skate (Bathyraja minispinosa) records......23 

Figure 24. Bathymetric distribution of whitebrow skate (Bathyraja minispinosa) records ....23 

Figure 25. Geographic distribution of mud skate (Bathyraja taranetzi) records.....................24 

Figure 26. Bathymetric distribution of mud skate (Bathyraja taranetzi) records....................24 

Figure 27. Geographic distribution of Irish lord (Hemilepidotus spp.) records.......................25 

Figure 28. Bathymetric distribution of Irish lord (Hemilepidotus spp.) records .....................25 

Figure 29. Geographic distribution of great sculpin (Myoxocephalus spp.) records...............26 

Figure 30. Bathymetric distribution of great sculpin (Myoxocephalus spp.) records..............26 

Figure 31. Geographic distribution of bigmouth sculpin (Hemitripterus spp.) records ..........27 

Figure 32. Bathymetric distribution of bigmouth sculpin (Hemitripterus spp.) records.........27 

Figure 33. Geographic distribution of eulachon (Thaleichthys pacificus) records..................28 

Figure 34. Geographic distribution of rainbow smelt (Osmerus mordax) records..................29 

Figure 35. Geographic distribution of capelin (Mallotus villosus) records.............................30 
vii

Discussion......................................................................................................................................31 

Conclusions....................................................................................................................................39 

Acknowledgments..........................................................................................................................40 

Citations.........................................................................................................................................41 

Appendix A. Sampling instructions..............................................................................................43 

Appendix B. Field guide to the skates of Alaska..........................................................................45 

Appendix C. Key to the smelts.....................................................................................................62 

Appendix D. Key to selected genera of North Pacific sculpins....................................................63 

Appendix E. Species identification time form (sample)...............................................................64 

Appendix F. Species codes...........................................................................................................65 

Appendix G. Skate species identification form ............................................................................66 
INTRODUCTION 

 Recent emphasis on ecosystem-level management of federally regulated marine fisheries 

has led to an increasing need for basic population data for species not traditionally targeted by 

fisheries. Many of these non-target species are relatively large, long-lived, and slow to 

reproduce and are therefore particularly vulnerable to fishing pressure, even if they are not 

directly targeted. The skates of Alaska (family Rajidae) and some genera of the sculpin families 

Cottidae (Hemilepidotus and Myoxocephalus) and Hemitripteridae (Hemitripterus) fall into this 

category (Zolotov and Tokranov 1989, Zeiner and Wolf 1993, Gallagher and Nolan 1999, 

Markevich 2000, Panchenko 2001). Skates are of particular concern due to the recent 

development of a commercial fishery targeting the largest of the skate species in the Gulf of 

Alaska near Kodiak. Additionally, many fishes – including walleye pollock and Pacific cod 

(Gadidae), herring (Clupeidae), smelts (Osmeridae), salmon (Salmonidae), and sandlances 

(Ammodytidae) – are widely recognized for their importance as forage for larger, commercially 

targeted fishes as well as marine mammals (e.g., Pitcher 1981, Merrick et al. 1997). 

 As the need for basic data on these groups of fishes has increased, researchers and 

fisheries managers have begun to seek additional sources of data to fill gaps in current 

knowledge. Currently, fisheries observers with the North Pacific Groundfish Observer Program 

(NPGOP) are required to identify all forage fishes except smelts to the species level, and to 

identify smelts, as well as skates and sculpins, only to the family level. Identification of these 

fishes to the species level would provide a great deal of additional species-specific population 

data to fisheries managers. 

 The objectives of this project were 1) to quantify the additional time observers would 

require on a per-haul basis to complete species-level identifications of all skates and smelts, and 
2

genus-level identifications of sculpins of the genera Hemilepidotus (Irish lords and butterfly 

sculpin), Hemitripterus (bigmouth sculpin), and Myoxocephalus (great sculpin, plain sculpin, 

etc.); and 2) to develop and assess the adequacy of a field guide to the skates of Alaska, a key to 

the smelts of Alaska, and a key to selected genera of North Pacific sculpins for use by observers 

in the field, as well as a training presentation to introduce these materials.

MATERIALS AND METHODS 

This project focused on observers with prior experience who returned for briefing at the 

Seattle office from July 2002 through March 2003. An attempt was made to train observers 

being deployed in as many different fisheries and seasons as possible. The training consisted of 

a 45-minute lecture session followed by a hands-on laboratory session with preserved specimens. 

The training session covered the project protocol (Appendix A) and tools, as well as the 

morphological features important in species-level identification of the skates and smelts and 

genus-level identification of species of Hemilepidotus, Hemitripterus, and Myoxocephalus likely 

to be encountered in commercial fisheries. Observers trained in this project were issued a Field 

Guide to the Skates of Alaska (Appendix B), a Key to the Smelts (Appendix C), and a Key to 

Selected Genera of North Pacific Sculpins (Appendix D). These materials were generated for 

this project and were continually updated and refined throughout the duration of the project. 

Once deployed at sea, observers were instructed to establish a block of approximately 

40 hauls during which to perform this project. Observers were instructed to employ an 

alternating sampling scheme to produce a series of experimental hauls and a parallel series of 

control hauls. During the designated block of hauls, species composition of the subsample was 

determined using standard procedures (AFSC 2003) for the first haul (with skates, smelts, and 
3

sculpins identified to the family level), and the time required to perform these identifications was 

estimated by the observer and noted on a Species Identification Time Form (Appendix E). For 

the next haul, and alternating subsequent hauls within the project block, all skates and smelts 

were identified to species and the selected groups of sculpins were identified to genus. The time 

to perform these identifications was estimated by the observer and noted on the Species 

Identification Time Form. Each participant thereby recorded a baseline series of identification 

times under control circumstances (Non-project hauls) and a parallel series of identification 

times including the experimental identification responsibilities (Project hauls). Species 

composition data were entered into the NORPAC database using species codes established for 

the project (Appendix F). 

Quantitative analysis of observer effort was accomplished by compiling the identification 

times reported by participants for both Project hauls (identification of skates and smelts to 

species and sculpins to genus) and Non-Project hauls (identification of skates, smelts, and 

sculpins to family). Mean identification time per haul was computed for Project and Non-Project 

hauls for each gear type and target species. Species composition data were retrieved from the 

NORPAC database for all project participants. 

Several approaches were used to assess the field guide and keys used to identify skates, 

smelts, and sculpins. Species Identification Time Forms included a “comments” field, in which 

participants were encouraged to describe any problems encountered while using the keys and 

field guide. Participants were also asked to identify any problems to their in-season advisors 

during deployment, and to their debriefers after deployment. Collection of specimens was 

encouraged whenever possible, and completion of a Species Identification Form was required 

each time a previously unidentified species was encountered. A new Species Identification Form
4

for skates was generated for this project (Appendix G), and several copies were issued to each 

observer during training. Finally, haul position and fishing depth data recorded for target species 

during this project were compiled and compared with geographic and bathymetric distribution 

data from recent Resource Assessment and Conservation Engineering (RACE) Division 

groundfish bottom-trawl surveys (1999-2003). Due to factors such as differences in seasonality 

of collections and the variety of gear types used in observed fisheries, RACE bottom-trawl 

surveys are not directly comparable with observer data as discussed below. However, these 

surveys have produced the most detailed and accurate distribution data available for noncommercial species in Alaskan waters and were therefore used along with published distributions 

(Mecklenburg et al. 2002) to help identify potential inconsistencies and misidentifications. 

Identifications were assessed by the author and NPGOP debriefers using Species Identification 

forms, interviews with observers, and collected specimens. 

RESULTS 

A total of 131 observers were trained in this project from July 2002 through March 2003. 

Of those trained, 67 submitted identification time data for a total of 1,917 hauls sampled. The 

distribution of effort represented by these hauls is summarized in Table 1. Most observer effort 

was distributed among the three major gear types (29% bottom trawl, 40% longline, and 30% 

pelagic trawl), but pot gear was represented by very few hauls (1%). Pacific cod (Gadus 

macrocephalus) fisheries accounted for nearly half (47%) of the sampling effort, while walleye 

pollock (Theragra chalcogramma) fisheries accounted for 30% and flatfish (primarily yellowfin 

sole, Limanda aspera, rock soles, Lepidopsetta spp., and flathead sole and Bering flounder, 

Hippoglossoides spp.) fisheries accounted for 18%. Atka mackerel (Pleurogrammus 
5

monopterygius), Pacific ocean perch (Sebastes alutus), sablefish (Anoplopoma fimbria), and 

Pacific halibut (Hippoglossus stenolepis) fisheries accounted for much smaller proportions of the 

data (4% total). 

Mean identification times per haul are summarized in Table 2 and Figures 1 and 2. The 

overall mean identification time was significantly greater for Project hauls than Non-Project 

hauls (P < .001). The mean overall difference between Project and Non-Project hauls was 

4.27 minutes, meaning that Project hauls required an average of 4.27 more minutes for specimen 

identification. For Project hauls, identification times were fairly consistent (approximately 

15 minutes per haul) among the three major gear types and among all target species. In pot 

fisheries, identification times were somewhat shorter. For Non-Project hauls, identification 

times were more variable among gear types, with means ranging from 8.53 to 13.24 minutes per 

haul for the three major gear types and from 9.17 to 14.55 minutes per haul for different target 

species. All mean identification times were associated with large standard deviations. For all 

gear types except pots and all target species except the “other” category, mean identification 

times were significantly greater for Project hauls than for Non-Project hauls, with differences 

between means ranging from 0.45 to 5.91. For Project hauls, mean identification time was 

highest (25.4 minutes) for the first haul of the series and declined over the first four hauls before 

stabilizing around 15 minutes per haul (Fig. 3). 

Skates, sculpins, and smelts were identified in 5,648 hauls (including 3,731 hauls for 

which no identification time data were collected) between 6 July 2002 and 25 October 2003. 

Unlike National Marine Fisheries Service (NMFS) bottom trawl survey data, which have been 

collected primarily during early summer, data for this project were collected throughout the year, 

with most effort occurring during late winter and late summer (Fig. 4). The number of hauls in 
6

which each taxon was encountered during the project and the total number of specimens of each 

taxon reported are summarized in Table 3, and broken down by gear type in Table 4. The Alaska 

skate (Bathyraja parmifera) was the most frequently encountered skate, and the most frequently 

encountered taxon overall. Other common skates included the Bering skate (B. interrupta) and 

Aleutian skate (B. aleutica). Sculpins of the genera Hemilepidotus and Myoxocephalus were 

also frequently encountered, with Hemilepidotus spp. often encountered in large numbers. 

Smelts were encountered much less frequently than either skates or sculpins. Species 

composition of skates was generally similar among the three major gear types, although 

deepwater species (e.g., Commander, roughtail, and whitebrow skates) were encountered almost 

exclusively in longline fisheries. One specimen of Bathyraja lindbergi was the only skate 

reported in a pot fishery. Sculpins were most abundant in the bottom trawl fisheries, although 

large numbers were reported in all types of fisheries. Hemilepidotus was the most commonly 

encountered sculpin genus in all types of fisheries except bottom trawls, in which 

Myoxocephalus was more common. Smelts were encountered primarily in pelagic trawl 

fisheries, with small numbers also being reported in bottom trawl fisheries. Eulachon was the 

most commonly encountered smelt species in both pelagic and bottom trawls. 

Participant feedback resulted in numerous refinements in the identification materials and 

training presentation. Comments on Species Identification Time forms were generally positive, 

indicating that participants were willing and able to learn to use the identification materials 

quickly and efficiently. Debriefing interviews with participants indicated similar results. 

Negative comments generally fell into two categories: extra time required to complete project 

paperwork, and poor durability of the identification materials and data sheets. Specimen 

collections were rare, and generally consisted of problematic specimens retained for 
7

confirmation. Of approximately 10 specimens collected by participants and examined by the 

author, only 2 were misidentified. These two specimens were mud skates (B. taranetzi) 

misidentified as Okhotsk skates (B. violacea). 

Project participants reported 11 of the 13 species of skates known from Alaskan waters. 

Skates of the genus Raja (big skates and longnose skates) were reported throughout the western 

Gulf of Alaska and into the southern Bering Sea, with some reports in the Pribilof Islands region 

and farther north (Figs. 5–8), and a small number of reports from the eastern Gulf of Alaska. 

Depth ranges for reports of big skates and longnose skates were 34–495 m and 61–391 m, 

respectively. The three most common species of Bathyraja (Alaska, Bering, and Aleutian 

skates) were all reported throughout the eastern Bering Sea (Figs. 9–14). Aleutian skates were 

also reported throughout the Aleutian Islands region and the western Gulf of Alaska. Alaska 

skates were commonly reported in the Aleutian Islands region, but only rarely reported from the 

Gulf of Alaska, and Bering skates (also known as sandpaper skates) were commonly reported 

from the Gulf of Alaska, but only rarely in the Aleutian Islands. All three species were reported 

at depths of approximately 30–700 m. Several less common species of Bathyraja 

(whiteblotched, Commander, and Okhotsk skates) were reported only from the outer shelf of the 

eastern Bering Sea and from the Aleutian Islands region (Figs. 15–20). The reported depth 

distributions of these three species were quite different. Whiteblotched skates were reported at a 

very broad range of depths (75–639 m), while Commander skates were reported only from

deeper waters (367–828 m) and Okhotsk skates only from shallower waters (74–205 m). 

Roughtail, whitebrow, and mud skates were rarely reported by project participants (Figs. 21–26). 

With one exception, roughtail and whitebrow skates were reported only from deep longline 

fisheries (506–695 m and 432–716 m, respectively), while mud skates were reported from
8

shallow depths (115–378 m) in trawl fisheries. Two species of skates known in Alaska only 

from deep waters, Roughshoulder skates (Raja badia) and deepsea skates (Bathyraja 

abyssicola), were not reported by any observers. All sculpin genera included in the study 

(Myoxocephalus, Hemitripterus, and Hemilepidotus) were reported throughout the western Gulf 

of Alaska, Bering Sea, and Aleutian Islands (Figs. 27–32), generally at depths of less than 200 

m. The only two species of smelt that were commonly encountered were eulachon (Thaleichthys

pacificus) and rainbow smelt (Osmerus mordax), and both were reported from the eastern Bering 

Sea and western Gulf of Alaska (Figs. 33–34). Capelin (Mallotus villosus) were more rarely 

encountered, and only in the Bering Sea (Fig. 35).
9

Table 1.--Distribution of hauls used to calculate mean identification times, by gear type and 

target species (see text for details of target species). 

 Project Non-Project Total 

Gear type 

 Bottom trawl 314 235 549 

 Longliner 411 363 774 

 Pelagic trawl 362 214 576 

 Pot 8 10 18 

Target species 

 Flatfishes 192 160 352 

 Pacific cod 499 408 907 

 Walleye pollock 362 214 576 

 Atka mackerel 26 28 54 

 Pacific ocean perch 4 0 4 

 Sablefish 5 4 9 

 Pacific halibut 7 8 15 

Grand total 1,095 822 1,917 

Table 2.--Mean identification time per haul (in minutes) for Project and Non-Project hauls, by 

gear type and target species (standard deviations in parentheses), difference between 

Project and Non-Project means, and one-tailed P values for two sample t-test. 

 Project Non-Project Difference P 

Gear type 

 Bottom trawl 16.35 (21.17) 13.24 (20.69) 3.11 0.043 

 Longliner 14.44 (15.14) 8.53 (10.52) 5.91 < 0.001

 Pelagic trawl 14.91 (15.72) 12.43 (13.62) 2.48 0.023 

 Pot 7.13 (8.36) 2.30 (2.83) 4.83 0.078 

Target species 

 Flatfishes 13.32 (15.63) 9.17 (15.59) 4.15 0.007 

 Pacific cod 15.91 (19.27) 10.25 (15.82) 5.66 < 0.001 

 Walleye pollock 14.91 (15.72) 12.43 (13.62) 2.48 0.023 

 Other 15.00 (9.14) 14.55 (8.26) 0.45 0.408 

All 15.09 (17.24) 10.82 (14.98) 4.27 < 0.001 
10

Table 3.--Number of hauls in which each taxon of skates, sculpins, and smelts was encountered 

during the project and total number of specimens of each taxon reported. 

Taxon Hauls Specimens

Skates

 Alaska skate (Bathyraja parmifera) 2,856 21,740

 Bering skate (B. interrupta) 575 1,999

 Aleutian skate (B. aleutica) 414 1,816

 Big skate (Raja binoculata) 151 915

 Whiteblotched skate (B. maculata) 94 337

 Longnose skate (R. rhina) 52 148

 Commander skate (B. lindbergi) 49 269

 Okhotsk skate (B. violacea) 42 199

 Roughtail skate (B. trachura) 37 74 

 Whitebrow skate (B. minispinosa) 22 46

 Mud skate (B. taranetzi) 7 8

Sculpins 

 Hemilepidotus spp. (Irish lords, etc.) 2,010 32,794

 Myoxocephalus spp. (great sculpin, etc.) 1,988 7,545

 Hemitripterus spp. (bigmouth sculpin) 996 1,996

Smelts 

 Eulachon (Thaleichthys pacificus) 225 4,393

 Rainbow smelt (Osmerus mordax) 99 2,806

 Capelin (Mallotus villosus) 10 42
11

Table 4.--Number of hauls in which each taxon of skates, sculpins, and smelts was encountered 

by each gear type during the project. 

Taxon Bottom

trawl 

Pelagic 

trawl 

Pot Longline

Skates

 Alaska skate (Bathyraja parmifera) 726 1,400 730

 Bering skate (B. interrupta) 45 151 379

 Aleutian skate (B. aleutica) 128 36 250

 Big skate (Raja binoculata) 115 6 30

 Whiteblotched skate (B. maculata) 17 77

 Longnose skate (R. rhina) 40 3 9

 Commander skate (B. lindbergi) 1 1 1 46

 Okhotsk skate (B. violacea) 5 37

 Roughtail skate (B. trachura) 37

 Whitebrow skate (B. minispinosa) 1 21

 Mud skate (B. taranetzi) 5 2

Sculpins 

 Hemilepidotus spp. (Irish lords, etc.) 859 399 169 583

 Myoxocephalus spp. (great sculpin, etc.) 1,119 290 40 539

 Hemitripterus spp. (bigmouth sculpin) 191 387 2 416

Smelts 

 Eulachon (Thaleichthys pacificus) 7 218

 Rainbow smelt (Osmerus mordax) 6 93

 Capelin (Mallotus villosus) 5 5
12

0

5

10

15

20

25

30

35

40

Bottom trawl Longliner Pelagic trawl Pot All

Gear type

ID time per haul (min)

Figure 1.--Average identification (ID) time (+ SD) per haul by gear type for Project hauls (white 

bars) and Non-Project hauls (black bars). 

0

5

10

15

20

25

30

35

40

Cod Pollock Flatfish Other All

Target species

ID time per haul (min)

Figure 2.--Average identification (ID) time (+ SD) per haul by target species for Project hauls 

(white bars) and Non-Project hauls (black bars). “Other” category includes Atka mackerel, 

Pacific ocean perch, sablefish, and Pacific halibut.
13

0

10

20

30

40

50

60

1 2 3456 789 10 11 12 13 14 15 16 17 18 19 20

Project haul number

ID time per haul (min)

Figure 3.--Average identification (ID) time (+/- SD) per haul for the first 20 Project hauls in a 

series. 

0.00

0.10

0.20

0.30

0.40

0.50

0.60

Jan

Feb

Mar

Apr

May

June

July

Aug

Sept

Oct

NovDec

Month

Proportion of records

Figure 4.--Seasonal distribution of data collection for this project (white bars) and 1999-2003 

NMFS bottom trawl surveys (black bars).
14

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Figure 5.--Geographic distribution of big skates (Raja binoculata) reported by Project 

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 6.--Bathymetric distribution of big skates (Raja binoculata) reported by Project 

participants.

Range: Bering Sea – southern California 
15

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Figure 7.--Geographic distribution of longnose skates (Raja rhina) reported by Project 

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 8.--Bathymetric distribution of longnose skates (Raja rhina) reported by Project 

participants.

Range: SE Bering Sea – California 
16

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")

Figure 9.--Geographic distribution of Alaska skates (Bathyraja parmifera) reported by Project 

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 10.--Bathymetric distribution of Alaska skates (Bathyraja parmifera) reported by Project 

participants.

Range: Bering Sea, Commander Islands – eastern Gulf of Alaska 
17

!(

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!(!(!(

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!(!(

!( !(!(!(!(

!(

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")

Figure 11.--Geographic distribution of Bering skates (Bathyraja interrupta) reported by Project 

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 12.--Bathymetric distribution of Bering skates (Bathyraja interrupta) reported by Project 

participants.

Range: Bering Sea – California 
18

!(

!( !( !(

!(!(!(!(

!(!(!(!(!!((!(

!(!

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")")

Figure 13.--Geographic distribution of Aleutian skates (Bathyraja aleutica) reported by Project 

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 14.--Bathymetric distribution of Aleutian skates (Bathyraja aleutica) reported by Project 

participants.

Range: Bering Sea, Aleutian Islands – California 
19

!(!(

!(!(!!(

!(!(

!(

!(!

!(!(

!(!(!!(

!(!(

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")

")

")

") ")")")

")

")")

")") ") ")

Figure 15.--Geographic distribution of whiteblotched skates (Bathyraja maculata) reported by 

Project participants (open circles), and distribution determined by recent bottom-trawl 

surveys (diagonally hashed area), including collected voucher specimens (open squares). 

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 16.--Bathymetric distribution of whiteblotched skates (Bathyraja maculata) reported by 

Project participants.

Range: Bering Sea, Kuril Islands – western Gulf of Alaska 
20

!(!(!(

!(

!(

!(

!(!(!!(!(!(!(!(

!(!(!!(!(

!(!!(!(!(

!(

!(!(

!(

")

")")

")

")

")

")

")

")

Figure 17.--Geographic distribution of Commander skates (Bathyraja lindbergi) reported by 

Project participants (open circles), and distribution determined by recent bottom-trawl 

surveys (diagonally hashed area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 18.--Bathymetric distribution of Commander skates (Bathyraja lindbergi) reported by 

Project participants.

Range: Bering Sea, Kamchatka – western Gulf of Alaska 
21

!(!(

!(!(!(!(!(

!(!!(

!(

!(!(!(!(!(!!(!(!(!(!(!(!(!( !(!(!(!(

!(

!(

!(

!(!!(!(!(!(

")

")

")

")

")

")

Figure 19.--Geographic distribution of Okhotsk skates (Bathyraja violacea) reported by Project 

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 20.--Bathymetric distribution of Okhotsk skates (Bathyraja violacea) reported by Project 

participants.

Range: Bering Sea, Aleutian Islands 
22

!(

!(

!(!(!

!(!(!!(!(!(!(!(!(!(

!(!(!(!(!(!

!(

")

")") ")

")

")

")")

") ") ")

")

")")

")

Figure 21.--Geographic distribution of roughtail skates (Bathyraja trachura) reported by Project 

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 22.--Bathymetric distribution of roughtail skates (Bathyraja trachura) reported Project 

participants.

Range: Bering Sea, Japan – California 
23

!(

!(!(!(!(

!(!!(!(!(!(!(

!(!(

!(!(

")

")")

")

")

")

")

")

")

Figure 23.--Geographic distribution of whitebrow skates (Bathyraja minispinosa) reported by 

Project participants (open circles), and distribution determined by recent bottom-trawl 

surveys (diagonally hashed area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 24.--Bathymetric distribution of whitebrow skates (Bathyraja minispinosa) reported by 

Project participants. 

Range: Bering Sea, Kamchatka – eastern Aleutian Islands 
24

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

Figure 25.--Geographic distribution of mud skates (Bathyraja taranetzi) reported by Project 

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 26.--Bathymetric distribution of mud skates (Bathyraja taranetzi) reported by Project 

participants.

!(

!(!!(!(!(

!(

") ")

")

") ")")")

")

")

")

")

")

")

")")")

")

")")

Range: Bering Sea, Aleutian Islands 
25

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Figure 27.--Geographic distribution of Hemilepidotus spp. reported by Project participants (open 

circles), and distribution determined by recent bottom-trawl surveys (diagonally hashed

area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 28.--Bathymetric distribution of Hemilepidotus spp. reported by Project participants.

Range: Japan – southern California, Arctic 
26

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Figure 29.--Geographic distribution of Myoxocephalus spp. reported by Project participants 

(open circles), and distribution determined by recent bottom-trawl surveys (diagonally 

hashed area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 30.--Bathymetric distribution of Myoxocephalus spp. reported by Project participants.

Range: Japan – Puget Sound, Arctic, North Atlantic 
27

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Figure 31.--Geographic distribution of Hemitripterus spp. reported by Project participants (open 

circles), and distribution determined by recent bottom-trawl surveys (diagonally hashed

area), including collected voucher specimens (open squares). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0-50

51-100

101-150151-200201-300301-400401-500501-600

>600

Depth (m)

Frequency

Figure 32.--Bathymetric distribution of Hemitripterus spp. reported by Project participants. 

Range: Bering Sea, Japan – northern California 
participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

28

Figure 33.--Geographic distribution of eulachon (Thaleichthys pacificus) reported by Project 

!(

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")

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")

Range: Bering Sea, Aleutian Islands – California 
29

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares).

Figure 34.--Geographic distribution of rainbow smelt (Osmerus mordax) reported by Project 

!(!(

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Range: Bering Sea, Japan – British Columbia, Arctic, North Atlantic 
30

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")")

Figure 35.--Geographic distribution of capelin (Mallotus villosus) reported by Project 

participants (open circles), and distribution determined by recent bottom-trawl surveys 

(diagonally hashed area), including collected voucher specimens (open squares). 

Range: Bering Sea, Japan – British Columbia, Arctic, North Atlantic 
31

DISCUSSION 

The implementation of ecosystem-based fisheries management relies on a more complete 

understanding of the ecosystem and its components. Fisheries observers can provide essential 

data on rapidly developing fisheries, such as the skate fishery that developed in the Gulf of 

Alaska in 2003, and are an important source of catch composition, abundance, and distribution 

data for both target and non-target species. In order to maximize the accuracy and resolution of 

their data, observers need clear and concise field identification materials, effective training and 

in-season advising, and efficient data collection strategies that do not place unrealistic demands 

on their time and resources. 

This project clearly demonstrated that additional identification responsibilities require 

additional time to be completed. Although statistically significant, the data also suggest that the 

additional effort is on the order of only a few minutes per haul. While observers on trawlers 

(targeting walleye pollock) appear to be least affected by these additional responsibilities and 

those on longline vessels appear to be most affected, the additional time required was not heavily 

dependent on the gear type or the target species. Identification times were greatest during the 

first few hauls of the project, but stabilized after about the fourth project haul and remained fairly 

consistent thereafter. This indicates that participants generally required three or four hauls to 

orient themselves and familiarize themselves with the identification materials. The high standard 

deviations associated with all mean identification times indicate that identification time varies 

significantly among different cruises and among different hauls within the same cruise. Causes 

of this variation may include differences in experience levels among observers, inconsistencies 

among working environments and conditions, varying diversity of catches, and differences in 

observer time estimation. 
32

Although this study suggests that observers will only need a few extra minutes per haul to 

complete these additional identifications, this increase in time requirement may be an 

underestimate of the effort observers will actually expend. This study did not investigate the 

possibility that additional time will be required to weigh or otherwise process the catch, and time 

required to complete additional paperwork, such as species identification forms, was not 

included in the identification time. In addition, some fisheries that are particularly likely to 

encounter diverse skate catches, such as the sablefish longline fishery, contributed a very small 

proportion of the data collected. In cases where an observer is required to identify and weigh 

several species of skates per haul, particularly if large specimens are encountered, identification 

and processing time may be significantly greater than estimated in this study. However, species 

composition data obtained from this study indicate that observers encounter a broad diversity of 

skates, smelts, and sculpins, and that these species may be encountered in large numbers. 

Lumping these observations into a few family-level categories can result in the loss of a great 

deal of information. If the family categories include taxa with dissimilar life histories or 

differing vulnerability to fishing pressure, then management at the family level may lead to 

significant declines in some taxa. 

A key element of this study was the development and assessment of a new field guide to 

the skates (Rajidae) of Alaska and new keys to Alaskan smelts and selected North Pacific sculpin 

genera for use by observers in the field. Progress toward this objective was measured in two 

ways: 1) by reaction and feedback from participating observers, and 2) by assessing the accuracy 

of field identifications. Observer feedback was predominantly positive throughout the life of the 

project, and resulted in numerous corrections, clarifications and updates, as well as one major 

reorganization of the field materials. Most participants believed the field guides to be clear, 
33

concise, and easy to use. When asked whether pre-deployment training was necessary and 

adequate, participating observers universally answered in the affirmative.

The accuracy of field identifications, particularly for the larger skate species, is difficult 

to assess directly. Observers often have access to only limited freezer space, and collections of 

larger specimens usually present significant logistical difficulties, so few specimens were 

retained for confirmation. However, the specimens that participants did collect were, with rare 

exceptions, identified accurately. 

The information gleaned from Species Identification forms and debriefing interviews is a 

useful indirect indicator of field identification accuracy, as the degree to which the observer is 

familiar with identifying features can be assessed. Although the quality of completed Species 

Identification forms and responses during debriefing interviews varied widely among 

participants, the majority of observers were able to demonstrate sufficient familiarity with the 

morphological characters important in identifying these fishes. Those that had difficulty with 

skate and/or sculpin identifications were quickly identified, and any questionable data for their 

cruises was scrutinized for accuracy and removed if deemed unreliable by the debriefer. The 

author provided supplemental identification and verification training for debriefers and assisted 

in the evaluation of questionable records. 

Comparisons of geographic and bathymetric distributions reported by participants in this 

study with known distributions of skates, sculpins, and smelts is another indirect means of 

assessing generalized field identification accuracy. This approach has the most potential with 

skates, many species of which have limited distributions in Alaskan waters. However, cases in 

which observer-reported distributions differ from survey distributions must be interpreted with 

caution. RACE bottom-trawl surveys are conducted only during the summer months (generally 
34

late May through early August), and very little is known about how much these species migrate 

seasonally and therefore how their distributions change over the course of the year. Distribution 

data collected from observers is much more seasonally diverse (Fig. 4). Thus, differences in the 

seasonality of the two data sets may contribute to differences in distribution reported for a 

particular species. 

Two species of the genus Raja (big skates and longnose skates) are known to be common 

in the Gulf of Alaska but are rarely encountered on bottom trawl surveys in the Bering Sea. As 

expected, participants in this study recorded these species primarily from the western Gulf of 

Alaska and southeastern Bering Sea near the western tip of the Alaska Peninsula. A few 

specimens were also reported further north in the Bering Sea, with one observer reporting big 

skates north of the Pribilof Islands. However, observers reporting big skates and longnose skates 

from these northern localities were unable to produce confirmation of their identifications, and 

therefore these records are of uncertain validity. Survey data indicate that these are generally 

shallow-water skates: big skates are most common at depths of less than 100 m, and longnose 

skates are most common at depths of 50–200 m. Project data agree with these bathymetric 

distributions remarkably well, as 85% of big skates reported by project participants were at 

depths of less than 100 m and 91% of longnose skates at 50–200 m.

The three most common species of Bathyraja have slightly different distributions in 

Alaskan waters. The Aleutian skate (B. aleutica) is the most widely distributed species, found 

throughout the Gulf of Alaska, Aleutian Islands, and Bering Sea. In contrast, the Alaska skate 

(B. parmifera) is rare in the Gulf of Alaska, and the Bering skate (B. interrupta) is not found in 

the Aleutian Islands. Aleutian skates have a very broad depth range, extending from the upper 

continental shelf to depths of at least 1,200 m, but appear to be most common at depths of 100–
35

300 m. In contrast, Alaska and Bering skates are generally restricted to shallower waters, and 

are rarely encountered at depths greater than 200 m. In general, distributions reported by 

participants in this project reflected these known skate distributions. Aleutian skates were 

reported throughout the western Gulf of Alaska, Aleutian Islands, and Bering Sea. Although 

most were reported at depths of less than 100 m, where the majority of observed fishing effort 

was concentrated, a significant number (17%) were at depths greater than 300 m. Alaska skates 

were reported throughout the Aleutians and Bering Sea, but from only a few locations in the Gulf 

of Alaska; Bering skates were reported throughout the Gulf of Alaska and Bering Sea, but only 

twice from the Aleutians. The Aleutian records of Bering skates could not be verified and their 

validity remains uncertain. Almost 97% of Alaska skates and 85% of Bering skates were 

encountered at depths of less than 200 m. These geographic and bathymetric distributions 

closely match expectations based on survey data. 

Several of the less common species of Bathyraja, including whiteblotched, Commander, 

whitebrow, and mud skates, have historically only been encountered in the Aleutians and Bering 

Sea, and are generally found in deeper waters. Whiteblotched and mud skates are most common 

at depths of 100–400 m, and Commander and whitebrow skates are only common at depths 

greater than 400 m. Again, data compiled from participants in this study generally reflect these 

distributions, as all four species were reported from the outer Bering Sea shelf and upper slope 

and the Aleutian Islands. Approximately 59% of whiteblotched skate reports and 100% of mud 

skate reports were at depths of 100–400 m, and 98% and 100% of Commander and whitebrow 

skate reports, respectively, were at depths greater than 400 m. 

Three of Alaska’s species of skates, the roughtail, roughshoulder, and deepsea skates, are 

restricted to deep waters. The roughtail skate is found throughout the Eastern Bering Sea and 
36

Gulf of Alaska but is rarely collected at depths of less than 500 m. Project participants reported 

this species primarily from the western Gulf of Alaska and Bering Sea, with 97% of the records 

occurring deeper than 500 m. The roughshoulder and deepsea skates are known from very few 

records in Alaska, and all have been encountered at depths greater than 1,200 m (Stevenson et al. 

in prep). As expected, participants in this project did not encounter these two species. 

The only skate species for which project distribution data differ markedly from survey 

distribution data is the Okhotsk skate (Figs. 19–20). This species is only rarely encountered on 

bottom trawl surveys, and has only been collected from the outer Bering Sea shelf and upper 

slope and from the central Aleutian Islands. Project participants reported this species much more 

frequently than expected (199 specimens in 42 hauls), primarily in the northern Bering Sea and 

far western Aleutians. The Okhotsk skate is much more common in the western Bering Sea and 

Sea of Okhotsk, so the distribution reported by observers is not entirely unreasonable. However, 

the lack of records in the survey data from these areas (particularly the western Aleutians) and 

the overall rarity of this species raise questions about the accuracy of these observer 

identifications. In addition, this species is generally difficult to identify and is commonly 

confused with the mud skate. In fact, the two specimens of Okhotsk skates that observers 

collected for confirmation were later reidentified as mud skates. Moreover, observers identified 

mud skates much less frequently than expected (8 specimens in 7 hauls). Survey data indicate 

that mud skates are much more common than Okhotsk skates in the eastern Bering Sea and 

Aleutians. Although these discrepancies could certainly be due to differences in seasonality of 

collections and gear types, it is perhaps more likely that participants in this project were

commonly misidentifying mud skates as Okhotsk skates. 

All three genera of sculpins included in this project are distributed throughout the Bering 
37

Sea, Aleutian Islands, and western Gulf of Alaska. Reports of Hemilepidotus are likely to 

include several species. The yellow Irish lord (Hemilepidotus jordani) is the most common Irish 

lord in Alaskan waters and is found throughout the continental shelf in the Gulf of Alaska, 

Aleutian Islands, and Bering Sea. However, the red Irish lord (H. hemilepidotus) is also found 

throughout the Gulf of Alaska and Aleutian Islands, the longfin Irish lord (H. zapus) is found 

throughout the central and western Aleutians, and the butterfly sculpin (H. papilio) is locally 

common on the Bering Sea shelf. Therefore, although the majority of records of Hemilepidotus

are probably yellow Irish lords, at least three additional species are probably represented in these 

data. Reports of Myoxocephalus are also likely to include several species. The great sculpin (M. 

polyacanthocephalus) is the most common member of this genus in Alaskan waters, but the plain 

sculpin (M. jaok) and warty sculpin (M. verrucosus) are also found throughout the Bering Sea, 

and the warty sculpin (M. scorpius of Mecklenburg et al. 2002) is also found throughout the Gulf 

of Alaska and Aleutian Islands. Reports of Hemitripterus probably represent only one species, 

the bigmouth sculpin (H. bolini). The only other species of this genus known from Alaska is the 

shaggy sea raven (H. villosus), which has been reported only once from Alaska (Mecklenburg 

et al. 2002). Although their bathymetric ranges differ slightly, with Hemilepidotus and 

Myoxocephalus generally found at shallower depths than Hemitripterus, there is broad overlap in 

the depths at which these genera may be found. Survey distributions and project distributions 

were generally congruent for these taxa. As expected, project participants encountered all three 

genera frequently in all fisheries and in all regions. 

For smelts, comparisons of survey distribution data with project distribution data are 

problematic. Survey distributions are based on data from bottom trawls, which are an inefficient 

means of collecting midwater fishes such as smelts. These distributions are probably skewed 
38

toward shallower depths, as a bottom trawl sweeps a larger percentage of the water column when 

fishing in shallow water. As anticipated, project participants encountered smelts most frequently 

in pelagic trawl fisheries, and much less frequently in bottom trawl fisheries. Despite the 

differences in gear type, smelt distributions reported by project participants appear to be largely 

in agreement with those established by survey data for eulachon and capelin. However, the 

distribution of rainbow smelt reported for this project differs markedly from the survey 

distribution. It is possible that this difference is due to widespread misidentification of smelts. 

However, observers did not report any difficulties in identifying smelts during training, midcruise advising, or debriefing for this project; there is no evidence that misidentification of these 

fishes is a widespread problem. Therefore, this difference is more likely due to biases in gear 

type or seasonality of collections. 

Overall, skate, sculpin, and smelt distributions compiled from study data do not differ 

dramatically from expectations based on survey data, and therefore, with the potential exception 

of the Okhotsk-mud skate confusion, do not indicate any widespread identification problems. 

Additionally, relative rates of encounter for skate species were similar to those indicated by 

survey data, again with the potential exception of the Okhotsk and mud skates, and bathymetric 

distributions of skates reported by project participants generally match those obtained from

survey data. 

Without widespread collection of voucher specimens or some other type of species 

identity documentation (such as photographs or tissue collections), the reliability of observer 

identifications cannot be directly assessed. These forms of documentation are logistically 

difficult or expensive to implement, but remain the only viable means of directly assessing 

observer identification accuracy on a long-term and widespread basis. For the current study, 
39

assessment of identification reliability must be based primarily on the indirect lines of evidence 

detailed above, supported by the few specimen collections that were made. These data suggest 

that the second objective of this study has been achieved. The identification materials and 

training presentation developed for this study constitute an adequate and sufficient set of 

resources for the reliable identification of skates, smelts, and selected genera of sculpins in the 

field. 

CONCLUSIONS 

The results of this project indicate that observers of the North Pacific Groundfish 

Observer Program (NPGOP) can identify skates and smelts to the species level and selected 

sculpins to the genus level without a great deal of additional training or time expenditure in the 

field. Although the reliability of observer identifications cannot be directly assessed without 

widespread voucher collection, the indirect evidence presented here indicates that observers 

identifications of these taxa are generally reliable. 

The frequency with which skates, sculpins, and smelts were encountered and the numbers 

of specimens reported during this project reinforce the fact that these fishes are important 

components of Alaska’s groundfish communities, and that they are at least potentially affected 

by groundfish fisheries. Therefore, even if these species are not directly targeted, the condition 

of their populations is relevant to the region’s fishery management strategies and conservation 

goals. 

The training presentation and identification tools developed during the course of this 

project have provided the classroom and field resources necessary for integrating these taxa into 

observer training. Therefore, it is now possible to implement this training for all NPGOP 

observers without major restructuring of the training schedules or sacrifices in data quality, 
40

thereby providing a wealth of additional data to scientists and fisheries managers at minimal 

additional cost. 

ACKNOWLEDGMENTS 

I thank each and every one of the scores of observers, observer trainers, observer 

debriefers, and data editors who assisted in the data collection for this project. Jerry Berger and 

Sheryl Corey assisted in the design and implementation of the project. Gerald R. Hoff, James W.

Orr, and other RACE Division personnel provided the photographs used in the skate guide. 

James W. Orr, Gerald R. Hoff, and Sheryl Corey reviewed earlier drafts of this manuscript. 
41

CITATIONS 

Alaska Fisheries Science Center (AFSC). 2003. North Pacific Groundfish Observer Manual. 

North Pacific Groundfish Observer Program. AFSC, 7600 Sand Point Way N.E., Seattle, 

Washington, 98115. 

Gallagher, M., and C. P. Nolan. 1999. A novel method for the estimation of age and growth in 

rajids using caudal thorns. Can. J. Fish. Aquat. Sci. 56:1590–1599. 

Markevich, A. I. 2000. Spawning of the sea raven, Hemitripterus villosus, in Peter the Great 

Bay, Sea of Japan. Russ. J. Mar. Biol. 26:283–285. 

Mecklenburg, C. W., T. A. Mecklenburg, and L. K. Thorsteinson. 2002. Fishes of Alaska. 

American Fisheries Society, Bethesda, Maryland.

Merrick, R. L., M. K. Chumbley, and G. V. Byrd. 1997. Diet diversity of Steller sea lions 

(Eumetopias jubatus) and their population decline in Alaska: a potential relationship. 

Can. J. Fish. Aquat. Sci. 54:1342–1348. 

Nakaya, K. 1983. Rajidae, p. 52–61, 167–171, 220–227, 310–313. In: Fishes from the 

northeastern Sea of Japan and the Okhotsk Sea off Hokkaido. K. Amaoka, K. Nakaya, H. 

Araya, and T. Yasui (eds.). Japan Fisheries Resource Conservation Association, Tokyo. 

Panchenko, V. V. 2001. Reproduction of snowy sculpin, Myoxocephalus brandti (Cottidae), in 

Peter the Great Bay, Sea of Japan. Russ. J. Mar. Biol. 27:329. 

Pitcher, K. W. 1981. Prey of the Steller sea lion, Eumetopias jubatus, in the Gulf of Alaska. 

Fish. Bull., U.S. 79:467–472. 

Zeiner, S. J., and P. Wolf. 1993. Growth characteristics and estimates of age at maturity of two 

species of skates (Raja binoculata and Raja rhina) from Monterey Bay, California, p. 87–

90. In S. Branstetter (ed.), Conservation Biology of Elasmobranchs. U.S. Dep. 
42

Commer., NOAA Tech. Rep. NMFS 115, p. 87–90. 

Zolotov, O. G., and A. M. Tokranov. 1989. Reproductive ecology of Hexagrammidae and 

Cottidae in the Pacific waters of Kamchatka. J. Ichthyol. 29:54–61. 
43

APPENDIX A

Sampling Instructions – Incidental Species Identification Project 

From time to time, observers are asked to increase the level of resolution associated 

with the species identification of select species groupings. At this time, we are 

considering asking observers to identify skates and smelts to the species level and 

some sculpins to the genus level. You have been assigned this special project to help 

us judge the feasibility of this request. 

This special project will be given to observers of all gear types, throughout 2003. 

The purposes of this project are: (1) to assess the adequacy of the tools provided for 

identifying skates and smelts to species and selected sculpins to genus, and (2) to 

quantify the amount of additional time observers need to complete these identifications. 

Sampling for this project consists of the following: 

1. Begin this project when your vessel begins encountering skates and/or numerous 

sculpins on a regular basis. The block of hauls during which you performed this 

project will hereafter be known as “project hauls.” 

2. Beginning with the first project haul, complete sample identifications as usual. 

Record data as usual for the database, keying all skates, sculpins and smelts only to 

family, and using standard species codes. 

3. Note the amount of time spent for identification of specimens on the Species

Identification Time Form, including comments you may have (see sample). If the 

identifications are not done during one block of time, you may need to estimate the 

time requirement. 

Haul Number – the sequential haul number of your cruise 

Subsample? – did you subsample the haul or sample the whole haul? 

Date – the date the gear was retrieved 

Special project sample? – did you identify the skates, sculpins and smelts? 

ID time – how long did you spend identifying the entire sample? 

Comments – please be as specific as possible 

4. Beginning with the second project haul, and continuing for alternating sampled hauls 

until at least 20 hauls are sampled, identify all skates and smelts to species, and all 

sculpins to genus category (Myoxocephalus, Hemitripterus, Hemilepidotus, or other) 

using the keys provided. Record data for the database, using standard species

codes and the new codes on the Special Project list. It is important to also include 

those that could not be completely identified (e.g. Bathyraja unident.). 
44

NOTE: Two of the species codes associated with this special project (roughshoulder 

skate and mud skate) are not in the ATLAS database. If you are using ATLAS and 

you encounter these species, write out the species name on the deck form or 3US 

form, and use species code 90 in the database (Skate unident.). 

6. Note the amount of time spent for identification of specimens on the Species

Identification Time Form, including comments you may have (see sample). If the 

identifications are not done during one block of time, you may need to estimate the 

time requirement. Comments should be related to the success or problems 

associated with the keys and guides or any difficulties that may have arisen. Note: 

ID Time does not include the time spent collecting the sample, only the time spent 

identifying the collected species. 

7. Fill out a Skate Species Description Form for each separate species of skate 

encountered and, if possible, retain the following specimens: 

roughshoulder skate 

deepsea skate 

any other species encountered out of range 

8. Make sure that you pick up several large plastic bags and waterproof tags when you 

pick up your gear. 

Contact: 

Duane Stevenson 

NMFS, Alaska Fisheries Science Center 

7600 Sand Point Way NE, Bldg. 4 

F/AKC1, RACE Division 

Seattle, WA 98115-0070 

Duane.Stevenson@noaa.gov 

(206) 526-4468 
45

APPENDIX B 

A Field Guide to the Skates (Rajidae) of 

Alaska 

Compiled by: 

Duane E. Stevenson 

National Marine Fisheries Service 

Alaska Fisheries Science Center 

Seattle, Washington 

*This document is a working draft, not to be cited 

or reproduced without permission. 

E-mail comments to duane.stevenson@noaa.gov 
46
47

2

KEY TO THE SKATES (RAJIDAE) OF ALASKA

1a. Snout firm to tip; pectoral fin rays fall distinctly short of tip of snout.....................

...............................................................................(genus Raja)....... 2

1b. Snout flexible, especially near tip; pectoral fin rays nearly reach tip of snout............

...........................................................................(genus Bathyraja).....4

2a.(1)Rostral thornlets present; two or three pairs of scapular thorns.............................

.........................................................roughshoulder skate (Raja badia p. 4)

2b. Rostral thornlets and scapular thorns absent..................................................3

3a.(2)Posterolateral margin of pelvic fin slightly concave; base of pectoral fin with large 

ocellus surrounded by ring of light spots; ventral surface nearly white; body

diamond-shaped.............................................big skate (Raja binoculata p. 5)

3b. Posterolateral margin of pelvic fin deeply notched; base of pectoral fin with ring of

dark pigment; ventral surface dark; body elongate with very long snout.................

................................................................longnose skate (Raja rhina p. 6)

4a.(1)Scapular thorns present.......................................................................... 5

4b. Scapular thorns absent...........................................................................7

5a.(4)Denticles absent from area surrounding tail thorns; orbital thorns present (but often

obscure)............................................Alaska skate (Bathyraja parmifera p. 7)

5b. Denticles surrounding tail thorns; orbital thorns absent.................................... 6

6a.(5)Mid-dorsal row of thorns usually interrupted; tail thorns reduced along length of tail, 

0-2 reduced thorns between dorsal fins; dorsal surface brown..............................

.......................................................Bering skate (Bathyraja interrupta p. 8)

6b. Mid-dorsal row of thorns continuous (may be worn down in older specimens); tail

thorns not reduced along length of tail, 1-2 strong thorns between dorsal fins; dorsal

surface gray........................................Aleutian skate (Bathyraja aleutica p. 9)
48

3

7a.(4)Ventral surface typically creamy white (may be blotchy); dorsal surface in life brown;

disc with thorns absent; median tail thorns weakly developed and progressively

smaller towards tip of tail.........................................................................8

7b. Ventral surface dusky, black, or blotchy; dorsal surface in life gray with white 

blotches, black, or dusky; disc with thorns absent, reduced, or strong; median tail

thorns strongly developed along entire length of tail........................................9

8a.(7)Body small and rounded, anterior margin of pectoral fin convex; tail length greater

than precaudal length............................... mud skate (Bathyraja taranetzi p. 10)

8b. Body large and triangular, anterior margin of pectoral fin concave; tail length less

than or equal to precaudal length..............Okhotsk skate (Bathyraja violacea p. 11)

9a.(7)Fine denticles on ventral surface of disc and tail..............................................

....................................................deepsea skate (Bathyraja abyssicola p. 12)

9b. Ventral surface of disc and tail smooth.......................................................10

10a.(9)Mid-dorsal thorns present...............Commander skate (Bathyraja lindbergi p. 13)

10b. Mid-dorsal thorns absent........................................................................11

11a.(10)Nuchal thorns present (rarely absent); dorsal surface with light blotches on disk 

or white patches between eyes; ventral surface light to medium brown................12

11b. Nuchal thorns absent; dorsal surface uniformly dark brown to black; ventral surface 

dark brown or black, often with whitish mouth and cloaca................................

.....................................................roughtail skate (Bathyraja trachura p. 14)

12a.(11)Nuchal thorns weak, 1-3 (rarely absent); dorsal surface uniform gray-brown to

dark brown, usually with white patches between eyes; ventral surface light to medium

brown, with white mouth.................whitebrow skate (Bathyraja minispinosa p. 15)

12b. Nuchal thorns moderate, 1-7; dorsal surface dark brown with white blotches; ventral 

surface of disk light and blotchy, with dark tail typically separated from lighter disk

by a distinct line.........................whiteblotched skate (Bathyraja maculata p. 16)
49

4

Raja badia roughshoulder skate

MALE

FEMALE

ventral

Diagnosis: The only Alaskan species of skate with

rostral thornlets, and the only species that commonly 

has 2-3 pairs of scapular thorns. Also the only

Alaskan species of Raja with scapular thorns.

Denticles: Dorsal surface evenly covered with

denticles; ventral surface smooth.

Coloration: Dorsal surface gray-brown, with darker

spots and blotches; ventral surface gray-brown, with

white blotches on snout, abdomen, and near mouth.

Body Shape: Disc somewhat diamond-shaped, with

slightly concave anterior margin; precaudal length

greater than tail length.

Juveniles:

Maximum Size: 98 cm

Range: Bering Sea to California

Depth: 1280-2322 m
50

5

Raja binoculata big skate

MALE

FEMALE

ventral

Diagnosis: The only Alaskan species of Raja with the 

following combination of characters: anterior margin

of disk concave; posterolateral margin of pelvic fin

slightly concave; and base of pectoral fin with large

ocellus surrounded by light spots.

Denticles: Fine denticles on dorsal surface; ventral

surface smooth.

Coloration: Dorsal surface brown, gray-brown or

reddish brown, often with large ocellus surrounded by

smaller spots on pectoral fin; ventral surface white to

light gray.

Body Shape: Disc wide, somewhat diamond-shaped,

with concave anterior margin; posterolateral margin 

of pelvic fin slightly concave.

Juveniles:

Maximum Size: 244 cm

Range: SE Bering Sea to California

Depth: 16-800 m
51

Raja rhina longnose skate

Diagnosis: The only Alaskan species of Raja with an

elongate snout and deeply notched pelvic fins.

Denticles: Fine denticles on dorsal surface; ventral

surface smooth.

Coloration: Dorsal surface brown with dark blotches, 

may have ocelli on disk; ventral surface gray to black.

Body Shape: Disc elongate with pronounced snout;

posterolateral margin of pelvic fin deeply notched.

Maximum Size: 180 cm

Range: Bering Sea to California

Depth: 24-675 m

6

MALE

FEMALE

ventral
52

Bathyraja parmifera Alaska skate

Diagnosis: The only Alaskan species of Bathyraja with

orbital thorns present and scapular thorns present. Also

the only species with naked area surrounding tail thorns. 

Row of mid-dorsal thorns may be complete or

interrupted. (B. rosispinis may be a synonym.)

Denticles: evenly distributed on dorsal surface of

juveniles, patchy on adults; ventral surface smooth.

Coloration: Dorsal surface dark brown or golden brown,

often with lighter spots or blotches; ventral surface brown

to white. *In Aleutians, dorsal surface with vivid oliveyellow “leopard” spotting pattern.

Body Shape: Tail length shorter than precaudal length.

Juveniles: Denticles evenly distributed.

Maximum Size: 112 cm

Range: Aleutian Islands, Gulf of Alaska, Bering Sea

Depth: 17-600 m

Note: Specimens with no trace of mid-dorsal thorns may 

be a separate species (B. smirnovi). MALE

FEMALE

ventral

7
53

8

Bathyraja interrupta Bering skate

MALE

ventral

Diagnosis: The only Alaskan species of Bathyraja

with the following combination of characters: orbital 

thorns absent; scapular thorns present; row of middorsal thorns usually interrupted; tail thorns reduced,

with 0-2 reduced thorns between dorsal fins.

Denticles: evenly distributed on dorsal surface;

ventral surface smooth.

Coloration: Dorsal surface light to dark brown;

ventral surface white.

Body Shape: Body roundish with short snout; tail

length equal to or greater than precaudal length.

Juveniles: Same as adults.

Maximum Size: 80 cm

Range: Bering Sea to California

Depth: 37-1372 m

FEMALE
54

9

MALE

FEMALE

ventral

Bathyraja aleutica Aleutian skate

Diagnosis: The only Alaskan species of Bathyraja 

with the following combination of characters: orbital 

thorns absent; scapular thorns present; row of middorsal thorns usually continuous; tail thorns large,

with 1-2 strong thorns between dorsal fins.

Denticles: evenly distributed on dorsal surface;

ventral surface smooth.

Coloration: Dorsal surface gray, with or without

vague black ocellus on pectoral fin; ventral surface

white with gray margin.

Body Shape: Body angled with elongate snout; tail

length equal to or greater than precaudal length.

Juveniles: Same as adults.

Maximum Size: 150 cm

Range: Aleutian Islands, Gulf of Alaska, Bering Sea

Depth: 29-950 m
55

10

MALE

ventral

Bathyraja taranetzi mud skate

Diagnosis: The only Alaskan species of Bathyraja

with the following combination of characters: disc

free of thorns; body small and rounded, with tail

length greater than precaudal length; ventral surface

white or cream colored.

Denticles: Small and fine, evenly distributed on

dorsal surface; ventral surface smooth.

Coloration: Dorsal surface brown with small darker

blotches, and usually a large lighter spot on posterior

part of pectoral fin; ventral surface white or cream

colored. *In Aleutians, dorsal surface with distinctive

yellow spots and blotches.

Body Shape: Body small and rounded; tail length

greater than precaudal length

Juveniles: Same as adults. 

Maximum Size: 70 cm

Range: Aleutian Islands, Bering Sea

Depth: 58-1054 m

FEMALE
56

11

MALE

FEMALE

Bathyraja violacea Okhotsk skate

Diagnosis: The only Alaskan species of Bathyraja

with the following combination of characters: disc

free of thorns; large triangular body, with tail length

less than or equal to precaudal length; ventral surface

white or cream colored.

Denticles: Dorsal surface with patches of small fine

denticles; ventral surface smooth.

Coloration: Dorsal surface gray to brown, often with

dark reticulations; ventral surface white or cream

colored.

Body Shape: Body large and triangular; tail length

less than or equal to precaudal length.

Juveniles: Same as adults.

Maximum Size: 73 cm

Range: Aleutian Islands, W Bering Sea

Depth: 47-520 m

ventral
57

12

MALE

FEMALE

Bathyraja abyssicola deepsea skate

Diagnosis: The only Alaskan species of Bathyraja

with fine denticles on the ventral surface.

Denticles: Fine, evenly distributed denticles on dorsal

and ventral surface.

Coloration: Dorsal surface gray to brown; ventral

surface gray to black, mouth and cloaca whitish, may

have white blotches.

Body Shape: Tail length greater than or equal to

precaudal length.

Juveniles: Same as adults.

Maximum Size: 140 cm

Range: Japan to California, Bering Sea

Depth: 362-2904 m

ventral

(Photo from Nakaya, 1983)
58

13

MALE

ventral

FEMALE

Bathyraja lindbergi Commander skate

Diagnosis: The only Alaskan species of Bathyraja

with the following combination of characters:

scapular and orbital thorns absent; nuchal and middorsal thorns present; ventral surface without

denticles.

Denticles: Dorsal surface with few, unevenly

distributed denticles; ventral surface smooth.

Coloration: Dorsal surface gray brown to black;

ventral surface gray to black, darker around pectoral

and pelvic fin margins, white around mouth and 

nostrils.

Body Shape: Tail length greater than precaudal

length.

Juveniles: Same as adults.

Maximum Size: 93 cm

Range: Bering Sea, Aleutian Islands, Japan

Depth: 160-1193 m
59

14

MALE

ventral

FEMALE

Bathyraja trachura roughtail skate

Diagnosis: The only Alaskan species of Bathyraja

with the disc free of thorns and a dark ventral surface.

Denticles: Small and fine, evenly distributed on

dorsal surface; ventral surface smooth.

Coloration: Dorsal and ventral surfaces dark brown 

to black, mouth and cloaca whitish.

Body Shape: Tail length less than precaudal length.

Juveniles: Same as adults.

Maximum Size: 85 cm

Range: Japan to California, Bering Sea

Depth: 213-1504 m
60

15

MALE

ventral

FEMALE

Bathyraja minispinosa whitebrow skate

Diagnosis: The only Alaskan species of Bathyraja

with white patches around the eyes. Also

distinguished by the following combination of

characters: scapular, orbital, and mid-dorsal thorns

absent; nuchal thorns present, but weak (occasionally 

absent); dorsal surface with fine denticles, ventral

surface without denticles.

Denticles: Fine denticles evenly distributed on dorsal

surface; ventral surface smooth.

Coloration: Dorsal surface gray brown to dark

brown, interorbital region and margins of orbits white;

ventral surface light to medium brown, mouth white.

Body Shape:

Juveniles: Same as adults.

Maximum Size: 82 cm

Range: Bering Sea, Aleutian Islands, Japan 

Depth: 160-1420 m
61

16

MALE

ventral

FEMALE

Bathyraja maculata whiteblotch skate

Diagnosis: The only Alaskan species of Bathyraja

with a distinct line on the ventral surface separating 

the dark tail from the light body. Also distinguished

by the following combination of characters: scapular,

orbital, and mid-dorsal thorns absent; nuchal thorns

present and strong; dorsal surface with strong

denticles, ventral surface without denticles.

Denticles: Dorsal surface covered with strong

denticles; ventral surface smooth.

Coloration: Dorsal surface gray with white or yellow

blotches; ventral surface blotchy gray, with dark

border; underside of tail dark, separated from lighter 

ventral surface of body by distinct line.

Body Shape:

Juveniles:

Maximum Size: 120 cm

Range: Aleutian Islands, Bering Sea, Russia

Depth: 84-1193 m
62

APPENDIX C 

KEY TO THE SMELTS

(Figures not reproduced due to copyright considerations) 

1A Adipose fin rectangular, attached along its entire length..........Capelin (Mallotus villosus) 

 Strait of Juan de Fuca to Bering Sea

1B Adipose fin rounded, attached only in front ........................................................................2 

2A(1) Opercle with distinct semicircular striations; pelvic fin origin anterior to dorsal fin origin. 

 ........................................................................................Eulachon (Thaleichthys pacificus) 

 Monterey Bay to Bering Sea

2B Opercle without striations; pelvic fin origin posterior to dorsal fin origin..........................3 

3A(2) Mouth large, maxilla extending to posterior margin of eye; two large canine teeth on roof

of mouth, teeth on tongue .............................................Rainbow smelt (Osmerus mordax) 

 Vancouver to Bering Sea 

3B Mouth small, maxilla not extending beyond mideye; canine teeth absent, teeth small and 

of uniform size ...............................................................Surf smelt (Hypomesus pretiosus) 

 Southern California to Gulf of Alaska 
63

APPENDIX D 

Key to Selected Genera of North Pacific Sculpins (Figures not reproduced due to copyright considerations) 

1 Spinous and soft dorsal fins broadly connected...................................................................2

1 Spinous and soft dorsal fins separate or adjacent ................................................................3

2(1) Spinous dorsal fin with deep notch (in one species 2 deep notches); broad band of scales 

(3-8 rows) at base of dorsal fin and another band below lateral line..................................... 

 ......................................................................................Genus Hemilepidotus (Irish lords)

2 Spinous dorsal fin without deep notch; scales not arranged as above ............... Cottidae sp.

3(1) Body covered with minute spines; head large, broad and depressed..................................... 

 ...........................................................................Genus Hemitripterus (Bigmouth sculpin)

3 Body not covered with minute spines or, if covered .. with minute spines then head small, 

 narrow and compressed........................................................................................................4 

4(3) Upper preopercular spine long, straight, and without branches or serrations; lateral line 

smooth, without scales or plates; anterior extent of upper and lower jaws approximately 

 equal..............................................................Genus Myoxocephalus (Great sculpin, etc.)

4 Upper preopercular spine not as described above or, if as described above then lateral line 

with prominent bony plates and/or lower jaw projecting anteriorly past upper Cottidae sp.
64

APPENDIX E 

Species Identification Time Form (Sample)

Vessel/Code Dominator/A999 Observer/Cruise Mary Jones/8765 

Gear Bottom Trawl Target Sp. Atka mackerel 

 

Haul Number Subsample? Date 

Special 

Project 

Sample? ID Time Comments 

No problems.

22 Yes 25-May No 10 min. 

Only a few skates, but three different 

24 Yes 25-May Yes 30 min. species. Some problems with the key. 

 

25 Yes 26-May No 12 min. 

A few skates and many sculpins, but 

26 Yes 26-May Yes 61 min. sculpin key works well. 

 

27 Yes 26-May No 20 min. 

No skates, sculpins, or smelts. 

28 Yes 26-May Yes 10 min. 

Bad weather made sampling difficult. 

31 Yes 27-May No 33 min. 

Many skates, but getting easier to ID. 

33 Yes 27-May Yes 21min. 

 

37 Yes 28-May No 18 min. 

Two new smelt species I haven't seen 

38 Yes 28-May Yes 38 min. before. 

 

39 Yes 28-May No 22 min. 

The most diverse haul yet. 

41 Yes 29-May Yes 48 min. 

 

44 Yes 29-May No 17 min. 

Many skates, difficult to identify because

45 Yes 30-May Yes 45 min. of many species. 
65

APPENDIX F 

Incidental Species Identification Special Project Species Codes 

SKATES

Code Common Name Scientific Name

94 Big skate Raja binoculata 

95 Longnose skate Raja rhina 

166 Roughshoulder

skate 

Raja badia

90 Skate unidentified Rajidae 

159 Soft-nosed skate Bathyraja sp. 

97 Bering skate Bathyraja interrupta 

85 Aleutian skate Bathyraja aleutica 

88 Alaska skate Bathyraja parmifera 

165 Mud skate Bathyraja taranetzi 

161 Okhotsk skate Bathyraja violacea 

92 Deepsea skate Bathyraja abyssicola 

163 Commander skate Bathyraja lindbergi 

89 Roughtail skate Bathyraja trachura 

162 Whitebrow skate Bathyraja minispinosa 

164 Whiteblotched skate Bathyraja maculata 

SCULPINS 

Code Common Name Scientific Name

407 Red Irish lord Hemilepidotus hemilepidotus 

414 Yellow Irish lord Hemilepidotus jordani 

410 Brown Irish lord Hemilepidotus spinosus

418 Irish lord unid. Hemilepidotus sp. 

405 Great sculpin Myoxocephalus 

polyacanthocephalus 

440 Myoxocephalus

unident 

Myoxocephalus sp. 

402 Bigmouth sculpin Hemitripterus bolini 

SMELTS 

Code Common Name Scientific Name

604 Capelin Mallotus villosus 

601 Eulachon Thaleichthys pacificus

605 Rainbow smelt Osmerus mordax 

613 Surf smelt Hypomesus pretiosus 
66

APPENDIX G 

Skate Species Identification Form

SPECIES COMMON NAME:______________________________________ 

DATE:_______________________ 

HAUL NUMBER:______________ 

TOTAL LENGTH: ______________ 

PRECAUDAL LENGTH: ______________ 

TAIL LENGTH: ______________ 

SPECIMEN COLLECTED? YES NO 

WHAT IS THE DORSAL COLORATION OF THE SKATE? 

uniform brown or gray dark with light blotches 

 uniform black dark with white “eyebrows” 

 other:________________________________________ 

WHAT IS THE VENTRAL COLORATION OF THE SKATE? 

 uniform light light, with dark tail 

 uniform dark dark, with white areas

 other:________________________________________ 

DENTICLES ON THE VENTRAL SURFACE? YES NO 

IS THE SPECIMEN A MATURE MALE? 

 YES NO, FEMALE NO, IMMATURE MALE 
67

WHICH SERIES OF THORNS ARE PRESENT? 

____ Rostral ____ Nuchal 

____ Orbital ____ Mid-dorsal 

____ Scapular 

DRAW THE THORNS ON THIS DIAGRAM – 

OTHER COMMENTS: ______________________________________________ 
RECENT TECHNICAL MEMORANDUMS


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