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Identification
and Systematics of Rockfishes (Sebastes)
in the Northeast Pacific Ocean
(Quarterly
Report for Jan-Feb-Mar 2001)
by Art Kendall and Jay Orr
![picture of rockfish](images/JFMcoverColor.jpg)
With slightly over
100 species worldwide and 33 species off Alaska,
identifying rockfishes is an ongoing challenge to
fishery biologists, fishermen, and casual observers
alike. Although many rockfish species were
described in the late 1800s, new species are
still being found today. This is partly
because the characters that distinguish the species
are often subtle and confusing. For
convenience, several similar appearing species
frequently are lumped in fisheries catch statistics.
Nevertheless, each species has unique
biological characteristics and should be managed
separately from all other species.
Populations of many rockfish species in the
Northeast Pacific Ocean are severely depleted, and
rebuilding efforts are called for. For such efforts
to be successful, the life history characteristics
of each species must be well understood. This
requires that all life history stages—larval,
juvenile, and adult—of the species can be
accurately identified. While accurate
identification of adults of some rockfish species is
difficult, accurate identification of larvae is
rarely possible at all.
In response to the need for more accurate
identification of rockfishes, scientists at the
Alaska Fisheries Science Center (AFSC) have
undertaken a variety of collaborative approaches to
studying rockfish of the Northeast Pacific. This
article describes several of those studies, the
progress that has been made to date, and some of the
challenges that remain.
The
Rockfish Database
Art Kendall and Jay Orr of the Center’s Resource
Assessment and Conservation Engineering (RACE)
Division have been conducting investigations on
various aspects of the taxonomy and systematics of Sebastes
for several years. In the process of these
studies, they accumulated a large amount of
information on characters of Sebastes species
worldwide, which they gleaned from the literature
used to define the species and subgenera of Sebastes.
The primary sources of information on adult Sebastes
species were original descriptions and Cramer
(1895), Matsubara (1943), and Ishida (1994). They
also reviewed keys and other sources, such as Hitz
(1965, and as updated in Hitz (1981)), Chen (1986),
Ishida (1984), and Orr et al. (2000) that contained
characters of many of the species of Sebastes.
They examined specimens of Sebastes
from the North Atlantic, because they could not find
adequate descriptions for several of their
characters in the literature. For data on
larvae and juveniles, they used original
descriptions and compilations of early life history
information such as Okiyama (1988), Matarese et al.
(1989), and Moser (1996). They also made extensive
use of unpublished data and figures by Laroche,
particularly for pelagic juvenile pigment. These
data were then compiled and tabulated to create a
computerized rockfish database, designed and
developed by Lisa Rugen, formerly with the AFSC.
The rockfish database includes data for 98 species
of Sebastes, and two species of Sebastiscus
with information on geographic distribution, adult
morphology, meristics, and head spines. For early
life history stages the database includes data on
preflexion pigment patterns, postflexion larval
characters, and pelagic juvenile pigment patterns.
Photographs of adult rockfish species and
illustrations of larvae and juveniles are also
included. Although each datum does not
presently link to a specific reference, a
bibliography of the references used for the data is
also presented.
The database is entered through one of seven
sections:
-
an introduction
-
a map showing
species occurring in various geographic areas
-
a
species-by-species listing of data
-
a search form to
select species having specified character states
-
a section to
compare larval and juvenile illustrations and
photographs of adults of several species
simultaneously
-
a list of
references used to construct the database plus
other references to literature on Sebastes
taxonomy and systematics
-
an
acknowledgments section where individuals and
organizations who have contributed data and
advice for the database are gratefully listed.
Geographic areas of occurrence
Geographic information on each species was collected
from the literature and RACEBASE, the RACE
Division’s survey database for the Northeast
Pacific Ocean and eastern Bering Sea. This
information was binned into 28 geographic areas: 12
in the Northeast Pacific, 13 in the Northwest
Pacific, 2 in the North Atlantic, and 1 in the
Southern Hemisphere. These 28 areas of occurrence
are labeled on an interactive
map of the North Pacific Ocean, where
clicking on each of the labeled regions displays a
drop down list containing the names of rockfish
species that occur in the region, their total
number, and the options to enter the
Species-by-Species section or the Compare Images
section of the database. The list of species
in those subsequent sections is then limited to
those species for the chosen geographic area.
Species-by-species listing of data
The Species-by-Species
section of the rockfish database presents
character states for more than 100 characters
displayed respectively for the database’s 100
rockfish species. Published illustrations of
larvae and juveniles and photographs of adults for
each species also can be viewed in this section. By
selecting from drop-down lists containing scientific
or common names or by entering a species name in an
empty field, the subgenus of the species is
displayed on screen along with a series of tabs
representing criteria specific to the selected
species.
The Species-by-Species Geographic Coverage tab leads
to a map of the North Pacific, with the areas of
occurrence of the selected species shown in red and
labeled. Clicking the Meristics tab displays
modal counts of a number of characters for the
species, such as number of spines and rays in each
fin and vertebrae. The Head Spines tab leads
to a diagram of the dorsal view of a rockfish head
with the spines for the particular species (as
benthic juveniles) illustrated and labeled. There
is also a note on the relative strength of the head
spines in adults. The Adult Morphology section
provides data on morphological features of the
species such as mouth size, jaw length, gas bladder,
and a color photograph of the species, if available.
Clicking the Cranial Osteology tab displays
character states of several features used in early
systematic analyses of Sebastes that together
define the shape of the skull of the species.
The database contains five early life history tabs.
The Preflexion Pigment tab leads to section of
the database containing computerized representations
of pigment loci displayed on a template of a preflexion
larva. A total of 27 pigment loci have been
identified on preflexion larvae. Illustrations of
larvae of each species contained in the database
were coded for the presence of pigment at each of
these loci. Clicking the Postflexion Larvae
tab reveals information on the morphology and
pigment of postflexion larvae. There are two
tabs for pigment on pelagic juveniles: Juvenile Body
Pigment and Juvenile Fin Pigment. The data for
these characters come largely from tables in an
unpublished manuscript by Wayne Laroche, a
specialist in juvenile rockfish morphology who
compiled data on juveniles and illustrated larvae
and juveniles of several species of rockfish while
under contract to the AFSC. The Larval and
Juvenile Images tab shows published drawings of
larvae and juveniles of the selected species. These
are grouped three-to-a-page, with the stage of
development, size of the specimen, and literature
source of the illustration also provided.
Illustrations are arranged on screen by stage of
development and can be scrolled to view additional
images when more than three of a species are
available. Clicking on an individual
illustration brings up an enlarged image. About
365 larval and juvenile illustrations were scanned
for this portion of the database.
Search for species with selected characteristics
The Search
section of the database allows searches
based on known character states of a specimen
through a series of drop down lists. Once all
known criteria have been entered, a click of the
Search tab queries the database and retrieves the
criteria searched on and a list of the species that
match those criteria. (Characters in the default
“any” or entered as “unknown” are not
listed.) The results of the query then lead
the user to either the Species-by-Species or the
Compare Images section of the database for the
species meeting the selection criteria. Queries are
available on adult, larval, and juvenile characters
categorized similar to those used with the
Species-by-Species listing of data. For example, for
a query on an adult specimen, subgenus, geographic
area, meristic data, cranial osteology, and adult
morphology can be specified through a series of
drop-down lists, or the characteristic can be typed
in. Head spines are handled a little differently.
The eight possible head spines are designated
with check boxes, which can be clicked for present
(a check mark), absent (default, blank) or unknown
(shaded).
The preflexion larval pigment template uses an
illustration of a preflexion larva with pigment
indicated at each of the 27 loci where pigment may
occur. Each of the 27 loci is associated with a
numbered box. The boxes are set at the default
unknown condition, denoted with a question mark.
Clicking the box once turns it yellow,
indicating that pigment is present at that locus.
Another click leaves the box white and deletes the
pigment area from the drawing, indicating that
pigment is absent from that locus. Once the pigment
on the drawing matches the pigment pattern of the
unknown larva, a query of the database retrieves a
report listing the species with that pigment
pattern.
Comparing images of several species
The Compare
Images section provides comparisons of
illustrations of larvae and juveniles or photographs
of adults of several species. Photographs of 77
species are currently in the database. Two
drop down options allow selection of species and
selection of developmental stage (extrusion,
preflexion, flexion or postflexion larvae,
juveniles, or adults). Only one developmental stage
of as many as 39 species can be selected per query.
Once the selections have been made, and the View
Images tab has been clicked, the screen displays the
images for the selected species and stage, along
with the size of the specimen (except for adults)
and the source of the image. The Compare
Images function displays up to 39 images per query
with a limit of 9 images per screen. Selected
species for which there are no images in the
database are listed at the top of the screen. Double
clicking on an image returns an enlarged image which
can be moved on the screen to reveal other portions
of the screen showing the rest of the selected
species. Only one image can be enlarged at a
time. Clicking the X in the upper right of the
enlarged image panel returns the image to its
original position and size. Images are
initially arranged alphabetically on the screen but
can be rearranged by clicking the desired species
name in the list under each image. This
replaces the image of the selected species for the
one that was there initially; thus, one can view the
same image more than once on the screen.
Only the names of species in the original
selection appear under the images.
Current and planned activities
The rockfish database will continue to develop.
The database can be used to store, search on,
and display many other kinds of information on
rockfishes. Any information (text or graphic)
that can be linked to a species of rockfish and is
available for a reasonable number of species (e.g.
genetic information) can be added. Data on
nomenclature and ecology have been tabulated and are
ready to be added to the database, as well as data
on ranges and frequency distributions of meristics.
The quality of the larval and juvenile images
in the database needs improvement, and data in
several other areas needs to be augmented. There
also are plans to convert the database to a format
suitable for the World Wide Web, so it will be
available to interested researchers worldwide.
Guides to the
Rockfishes of the Northeast Pacific
The rockfishes of the northeast Pacific Ocean north
of Mexico comprise five genera, three of which are
detailed in the NOAA Technical Memorandum Guide
to Rockfishes (Scorpaenidae) of the Genera Sebastes,
Sebastolobus, and Adelosebastes of the Northeast
Pacific Ocean by Jay Orr, Mike Brown (also
of the Center’s RACE Division) and Dave
Baker (formerly of the Center’s North Pacific
Groundfish Fishery Observer Program). The guide was
published first in 1998 and an updated version in
2000. The second edition of the guide contains color
images of 68 species photographed under natural and
electronic flash conditions in the field and
includes 21 additional photographs not available
when the guide was first published in 1998. Most
specimens were photographed immediately after
collection; 12 species photographed underwater are
also included in a separate section. The second
edition includes color photos of all species of Sebastes,
Sebastolobus, and Adelosebastes in the
U.S. waters of the Pacific Ocean, except for two
species, the dwarf red rockfish, Sebastes rufinanus,
and semaphore rockfish, S. melanosema, which
were collected in the 1970s and known only from the
type specimens. These two species are represented by
line drawings, produced from published photographs
of the types.
Of the guide’s excellent photographs, about 80%
were provided by research fishery biologist and
photographer Bob Lauth (RACE). Other
photographs were graciously contributed by Ann
Cleveland (North Pacific Groundfish Fishery Observer
Program), Blaise Eitner (Southwest Fisheries Science
Center (SWFC)), Tony Gharrett (University of
Alaska), Red Kessler (RACE), Carol Kimbrell (SWFC),
Milton Love (University of California, Santa
Barbara), Axa Rocha- Olivares (Scripps Institution
of Oceanography (SIO)), and H. J. Walker (SIO).
Both editions present key characters useful in
identifying rockfishes, including head spine
characters, color notes, and meristics. The
most significant characters are highlighted directly
on the photos in each species account. Habitat
information is presented for depths and geographic
distribution. Comparative information is
presented in a “Similar Species” section to
facilitate identification of easily confused
species. Both editions of the guide are available on
the AFSC Web site (http://www.afsc.noaa.gov).
The first edition at http://www.afsc.noaa.gov/
groundfish/rockfishguide/index.htm
is a navigable HTML document. The second edition is
available in PDF format at
http://www.afsc.noaa.gov/race/media/publications/
archives/pubs2000/techmemo117.pdf
A History of
Sebastes Systematic Studies
Other studies on the identification of rockfish
species at the Center include Art Kendall’s
manuscript reviewing the history of Sebastes
systematic studies. The paper examines the worldwide
history and status of taxonomic studies on Sebastes,
and reviews the 23 subgenera that have been erected
over the years. This review of research, which
includes morphological and genetic studies, provides
a framework against which to evaluate studies using
new genetic techniques. The manuscript is scheduled
for publication in the Marine Fisheries Review
(Kendall, A. W. Jr. A historical review of Sebastes
taxonomy and systematics. Mar. Fish. Rev. in press).
The beauty and astonishing diversity of the
rockfishes has generated both excitement and
bewilderment among scientists who have studied them
over the years. Kendall strives to
capture this sense of scientific discovery as he
reviews the history of the studies. He reviews the
initial description in the 1770s of a species of Sebastes
from the northeast Atlantic and the incredible
taxonomic diversity of the genus as more and more
species were discovered in Northeast Pacific waters
in the late 1800s. The paper examines the many
taxonomic problems the genus Sebastes
presents. For example, early efforts to
understand relationships among the species resulted
in the erection of several subgenera. Some
biologists accepted these subgenera while others did
not. This generated heated debates in the
scientific literature of the late 1800s, but did
little to advance our understanding of the
relationships among these fishes. In the mid-
1900s, new genetic techniques were applied to the
taxonomy of rockfishes, and progress in
understanding population structure of some species
was developed. However, relationships among
most of the species within the genus remain elusive
even today. The position of the genus within
the order Scorpaeniformes, as well as the limits of
the genus and the validity of some species remain
unresolved. Ongoing genetic and traditional
morphological research offers promise to resolve
these problems, but the incredible diversity and
wide geographic range of the genus make this an
enormous task.
Systematics of
the Dusky Rockfishes (Sebastes ciliatus)
![picture of light and dark dusky rockfishes](images/feature_dusky_light_dark.jpg)
Light (above) and dark dusky rockfishes
Jay Orr and Jim
Blackburn (Alaska Department of Fish and Game) have
completed a manuscript on the recognition of the
light and dark dusky rockfishes as distinct species,
based on morphology. Orr also has collaborated with
molecular biologists Paul Bentzen (University of
Washington (UW)), J. Andres Lopez (UW),
and Peter Wimberger (University of Puget Sound) on
studies of the mitochondrial and microsatellite DNA
of the two species. The manuscript describing
the two species and presenting taxonomic conclusions
will be submitted in 2001.
The two species have
been confused by ichthyologists and fishery
biologists since their original description. Both
were described in the early 1800s from dried
specimens collected from the Aleutian Islands and
the Kamchatka Pennisula during the Russian
explorations of the mid-1700s. The species
have recently been identified by general
coloration as the light and dark dusky rockfishes.
The light dusky rockfish is a highly variable
species, which ranges primarily over the outer
continental shelf, while the dark dusky rockfish is
a uniformly dark species that is typically found in
much shallower water. Specimens have been
examined from throughout the range of both species,
including the last remaining type of the ciliatus
species complex. Orr and Blackburn’s study
was built upon initial collections made by Blackburn
from sites around Kodiak Island, where both species
were collected together. Much additional
material was collected during RACE survey cruises in
the Gulf of Alaska and Aleutian Islands, where the
bulk of the deeper water specimens from the margin
of the continental shelf were obtained. More
shallow water specimens were collected during a
survey of the inshore waters of Southeast Alaska
with members of the AFSC’s Auke Bay Laboratory
(ABL). Especially important among the
specimens was the collection of near-shore light
duskies with dark duskies. Samples from Kamchatka
and the Commander Islands and from Canada were
obtained through loans from the Kamchatka Institute
of Ecology in Petrapavlovsk and the British Columbia
Royal Museum in Victoria, respectively.
Systematics
of the Rougheye Rockfishes (Sebastes aleutianus)
Sharon Hawkins (ABL), Jon Heifetz (ABL), and Orr are
conducting research into the specific status of
rougheye rockfish populations. The work was
initiated by Hawkins and Heifetz as part of a
population genetic study of rougheye rockfish
populations of Alaska (described in the feature
article “Genetic Population Structure of Rougheye
Rockfish (Sebastes aleutianus) Inferred from
Allozyme Variation,” AFSC Quarterly Report,
July-Sept 1997). The study found highly
significant differences in genetics between fish
collected from the Aleutian Islands and those
collected from the Gulf of Alaska. Jay will be
contributing the morphological and nomenclatural
work towards species-level recognition of these
populations.
Use of
Genetic Techniques to Identify Larval Sebastes
The use of traditional morphological techniques has
been largely unsuccessful in identifying the species
of Sebastes in plankton collections. It
is relatively easy to identify a larva as belonging
to the genus Sebastes, but usually impossible
to identify which of the many species it represents.
Genetic techniques which require minute
amounts of tissue offer promise in resolving these
identification problems. Because such
techniques generally require fresh, unpreserved
material, they may not be useful with routine
sampling programs, but they can help in establishing
the identity of unknown specimens, whose morphology
can then be described. This will allow preserved
specimens from routine sampling to be identified.
Art Kendall, in collaboration with A.J. Gharrett and
University of Alaska graduate student Andy Gray, has
been studying the application of genetic techniques
they have developed for adult Sebastes to
samples of larvae. During a 1998 field study
in Southeast Alaska aboard the NOAA research vessel John
N. Cobb, Kendall, Gray, and Bruce Wing
(ABL) collected Sebastes larvae with plankton
nets, photographed and sketched them while fresh,
and preserved them in fluid for later mitochondrial
DNA (mtDNA) analysis. A total of 67 larvae
were subjected to both pigment and genetic analysis.
All larvae were small and were little
developed beyond the extrusion stage. The
larvae were grouped into eight pigment groups;
genetic analysis found that seven species were
represented. With few exceptions, there was
poor agreement between the pigment groups and the
genetic identity of these larvae. Based on
this study, identification of larvae using mtDNA
analysis is effective, but identification based on
pigment remains problematic. (See: “A
comparison of genetic identifications and pigment
patterns of Sebastes larvae caught on NOAA
ship John N. Cobb cruise 9809: AFSC Proc.
Rep. 2001-02.”)
In another study, aboard the Japanese training ship Oshoro
Maru in the Bering Sea during summer 1999,
Kendall retrieved Sebastes larvae fresh from
plankton net collections, sketched them and noted
their pigment patterns, and preserved them for later
mtDNA analysis in Gharrett’s laboratory. Three
species of larvae were identified genetically, S.
alutus (Pacific ocean perch), S. polyspinis
(northern rockfish) and S. borealis
(shortraker rockfish). These larvae were
larger and better developed than those from the Cobb
cruise, and were distinct morphologically. Larvae
of S. alutus were slightly larger than those
of S. polyspinis, indicating that S.
alutus releases larvae earlier in the year than S.
polyspinis does. The morphology of none of these
species was well known, and larvae of S. borealis
were totally unknown. Results of this study
will lead the way toward identification of these
important species in routinely collected plankton
samples.
Curation of
Rockfishes at the University of Washington
Most of the specimens used in the production of the
rockfish guide and examined in the systematics study
of dusky and rougheye rockfishes have been preserved
as vouchers in the University of Washington Fish
Collection. As the result of collaborative work with
the collection’s curator Ted Pietsch and research
associates, hundreds of specimens of most species of
eastern North Pacific rockfishes have been archived
and are readily available on loan for examination by
researchers around the world. Records of the
cataloged specimens of rockfishes, as well as other
vouchers for RACE surveys, are available through the
Fish Collection site at http://artedi.fish.washington.edu/.
Literature
Cited
Chen, L. 1986. Meristic variation in Sebastes
(Scorpaenidae) with an analysis of character
association and bilateral pattern and their
significance in species separation. NOAA Tech.
Rep. NMFS No. 45. 17 p.
Cramer, F. 1895. On the cranial
characters of the genus Sebastodes
(rock-fish). Proc. Calif. Acad. Sci., ser. 2,
vol. 5, no. 1, p. 573-610, pls. 57-70.
Hitz, C. R. 1965. Field identification
of the northeastern Pacific rockfish (Sebastodes).
U.S. Dept. Interior, Fish and Wildl. Serv.,
Bur. Commer. Fish., Circ. 203. 58 p.
Hitz, C. R. 1981. Field identification
of northeastern Pacific rockfish (Sebastodes).
Revised by K. M. Howe, Contrib. No. 11, Coop. Syst.
Progr. College Fish. (Univ. Washington) and
Northwest Alaska Fish. Cent. (Natl. Mar. Fish.
Serv., NOAA).
Ishida, M. 1984. Taxonomic study of the
sebastine fishes in Japan and its adjacent waters.
M. Sc. Thesis, University of Hokkaido,
Hakodate. 245 p.
Ishida, M. 1994. Phylogeny of the suborder
Scorpaenoidei (Pisces: Scorpaeniformes). Bull.
Nansei Natl. Fish. Res. Inst. 27: 1-112.
Laroche, W. A. in prep. Guide to larval and
juvenile rockfishes (Sebastes) of North
America. 311 p.
Matarese, A. C., A. W. Kendall, Jr., D. M. Blood,
and B. M. Vinter. 1989. Laboratory guide to
early life history stages of northeast Pacific
fishes. U.S. Dep. Commer., NOAA Tech. Rep. NMFS
Circ. 80, 656 p.
Matsubara, K. 1943. Studies on the
Scorpaenoid fishes of Japan. Anatomy, phylogeny and
taxonomy, I, II. Trans. Sigenkagaku Kenkyusyo
Nos. 1 and 2. Tokyo. 486 p.
Moser, H. G. 1996. Scorpaenidae:
scorpionfishes and rockfishes. pp. 733-795. In: H.
G. Moser (ed.) The early stages of fishes in the
California Current region. CalCOFI Atlas 33.
Okiyama, M. (ed.) 1988. An atlas of the early
stage fishes in Japan. Tokai University Press.
Orr, J. W., M. A. Brown, and D. C. Baker. 2000.
Guide to the rockfishes (Scorpaenidae) of the
genera Sebastes, Sebastolobus, and Adelosebastes
of the northeast Pacific Ocean, second edition. U.S.
Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-117.
47 p.
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