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The organization of the website allows the user to browse through 296 taxa currently included in the IIS (Table 8) or search the database by a number of fields, including meristic and pigmentation characters, permitting those without access to collection material to attempt identification of unknown early life history (ELH) fish specimens. For each taxon, there is a gateway webpage with tabs that direct the user to meristic data, life history and ecological data, ELH descriptions, illustrations, spatial and temporal distribution and abundance data, and relevant literature. Phylogenetic order generally follows Nelson (2007) and Nelson et al. (2004) and scientific names follow Robins et al. (1991) and Nelson et al. (2004). The distribution data include maps and links to the original collection data, which can be downloaded to the user's personal computer. An additional benefit of the online format of the IIS is that it is linked directly with the UWFC where a majority of the specimens are deposited, thus allowing the user quick access to specimens of interest. Other available links from the IIS main page: Character search, Taxonomic Search, Citations, Species Dictionary, Links, and Contact Information. Users are encouraged to provide suggestions and comments as well as updated data and information to the Webmaster.

Character Search

This option is designed to use for an unidentified egg or larval fish specimen from the Northeast Pacific (U.S. West Coast and Gulf of Alaska), Bering Sea, or U.S. Arctic (Chukchi Sea and Beaufort Sea). The first step is to determine the developmental stage of the specimen. A character search can be used for a specimen of unknown life history stage (choose 'All Stages'). Although results will be more accurate if a particular stage is specified, choosing 'All Stages' will produce the most matches to the search criteria, thereby increasing the chance that the unidentified fish larva will be included in the list of matches.

Developmental Stage (Fig. 5)

Life history stage definitions --

EGG/EMBRYO STAGE (spawning to hatching): There are two general categories of diagnostic characters pertaining to fish eggs. First, there are the characters related to the egg itself: egg diameter and shape; envelope sculpturing and color; yolk diameter, pigmentation, and character (homogeneous or segmented); number, size, and position of oil globules; and width of perivitelline space. Characters used here are egg diameter (mm), number of oil globules, and oil globule size. There is also a set of diagnostic characters for the embryo developing within the egg: pigmentation, timing of development, body shape, number of myomeres, and presence or absence of elongate fin rays. Of these, pigmentation is the only character used here.

Augmenting the character search are six detailed tables with additional diagnostic characters to aid in identification of pelagic eggs. Egg diameter is one of the first characters used in the process. Tables with the diameters of all of the eggs that have been collected within the study area list those taxa whose eggs are 0.5 - 1.0 mm (Table 9), 1.0 - 2.0 mm (Table 10), 2.0 - 3.0 mm (Table 11), and 3.0 - 4.0 mm (Table 12) in diameter. As egg diameters are described as a range, a species name may appear in Tables 9 - 12 more than one time. In addition, a table lists the diameters of all eggs that contain oil (Table 13); numbers of oil globules and their diameters are also shown. A table of distinguishing characters of eggs is arranged in order of egg diameter and, in addition to including information about the chorion, oil, yolk, and pigment, characters are listed that are useful to differentiate similar taxa (Table 14). Finally, a table of the frequency of occurrence of eggs collected in the Gulf of Alaska and Bering Sea and off the U.S. west coast will further guide the reader as to the likelihood of collecting a particular taxon (Table 15).

YOLK-SAC STAGE (hatching to complete absorption of yolk sac): Larvae hatch from the egg at various stages of development. For larvae hatched from pelagic marine eggs, hatching generally occurs before the yolk sac has been completely absorbed. However, the larvae of species with demersal eggs often bypass the yolk-sac stage, absorbing the yolk while in the egg, and usually emerge as preflexion larvae. In species that do have a yolk-sac stage, larvae usually hatch without functional mouths, eye pigment, and differentiated fins. Diagnostic characters for yolk-sac larvae include body size and shape, gut shape and length, pigment patterns, number of myomeres, size and shape of yolk sac, oil globule size and position, and presence or absence of specialized larval characters such as elongate fin rays, enlarged finfolds, and stalked eyes. Of these, pigment patterns, number of myomeres, and other meristic counts, if applicable, are used here.

PREFLEXION STAGE (complete yolk-sac absorption to start of notochord flexion): The preflexion stage begins once both hatching and complete absorption of the yolk sac have occurred and ends with the start of notochord flexion. Diagnostic characters for preflexion larvae are similar to those for other larval stages: meristics (myomeres, fin rays), body size and shape, fin development sequence, gut shape and length, pigmentation pattern, presence or absence of head spines, and presence or absence of specialized larval characters such as fin-ray ornamentation, stalked eyes, and a trailing gut. Of these, pigment patterns, number of myomeres, and other meristic counts, if applicable, are used here.

FLEXION STAGE (start of notochord flexion to completion of notochord flexion): The flexion stage is defined as beginning with the dorsal bending of the notochord tip concurrent with development of the caudal-fin rays and supporting skeletal elements. Diagnostic characters for this stage are similar to those for other larval stages: meristics (myomeres, fin rays), body size and shape, fin development sequence, gut shape and length, pigmentation pattern, presence or absence of head spines, and presence or absence of specialized larval characters such as fin-ray ornamentation, stalked eyes, and a trailing gut. Of these, pigment patterns, number of myomeres, and other meristic counts, if applicable, are used here. Additionally, osteological characters, such as the sequence and timing of ossification, become useful during this stage. The flexion stage ends when the notochord tip has reached its final position at approximately 45 degrees from the notochord axis and the principal caudal-fin rays and supporting skeletal elements are in the adult longitudinal position. The supporting skeletal elements may or may not be completely developed.

POSTFLEXION STAGE (completion of notochord flexion to start of metamorphosis): The postflexion stage begins after the completion of notochord flexion and ends at the onset of metamorphosis (transformation). Diagnostic characters for this stage are similar to those for other larval stages: meristics (myomeres, fin rays), body size and shape, fin development sequence, gut shape and length, pigmentation pattern, presence or absence of head spines, presence or absence of specialized larval characters such as fin-ray ornamentation and stalked eyes, and osteological characters such as timing and sequence of bone and cartilage development. Of these, pigment patterns, number of myomeres, and other meristic counts, if applicable, are used here.

TRANSFORMATION STAGE (start of metamorphosis to completion of fin-ray development and beginning of scale formation; not currently available as a stage option for search engine, specimens generally considered late postflexion): The loss of larval characters and the attainment of juvenile/adult characters distinguish the transformation stage. Changes in body shape and pigment pattern can be dramatic. Additional changes that may occur include fin migration, photophore formation, loss of specialized larval characters, eye migration, and scale formation. The transformation stage is generally defined as ending with the completion of fin-ray development and the onset of scales. The duration of this stage differs among taxa.

JUVENILE STAGE (completion of fin-ray development and start of scale formation to attainment of sexual maturity): Individuals that have reached the juvenile stage of development generally resemble small adults. Although the juvenile stage is characterized by the attainment of different developmental landmarks in different families, scale formation and complete ossification of the skeleton occurs during this period. The stage ends with the attainment of sexual maturity.

OTHER STAGES: For several taxonomic groups, exceptions were made to the generalized life stage classification used above, e.g., rockfishes (extrusion larvae are categorized as yolk sac), leptocephalus larvae (pigment only filled out for "postflexion" stage), macrourids ("Preanal-fin formation" stage larvae are categorized as "preflexion," and later stage "Anal-fin formation" specimens are categorized as "postflexion" [Ambrose 1996]), and gadids ("preflexion" have no caudal-fin elements yet developed, "flexion" exhibit some caudal-fin element development, "postflexion" exhibit near-completion of caudal-fin element development, "juvenile" indicate that caudal-fin elements are complete)

Character Search Criteria

The IIS allows you to search by meristic characters, pigment characters, or both.

Meristic -- You may search on any or all of the following meristic characters:

Exceptions to meristics: For gadids and macrourids, the dorsal "spine" counts actually refer to the sum of elements in the first dorsal fin, while the dorsal "ray" counts refer only to rays found in the second dorsal fin.

Pigment -- You may search on any combination of the following pigment characters (Fig. 6):

Photophores -- Although photophores are found in various regions of the body, pigment associated with photophores during or after formation is considered distinct from the melanistic pigment described above, and is not included in any of the previous pigment definitions. Instead, photophore illustrations of myctophids (Fig. 7) , gonostomatids (Fig. 8) , sternoptychids (Fig. 9) , and stomioids (Fig. 10) (with accompanying photophore key (Table 16) are available as identification tools.

Taxonomic Search

The IIS allows you to browse, alphabetically or phylogenetically, the list of species included in the system through a taxonomic search. Alternatively, the user can select taxa by order, family, genus, or common name using the drop down lists that appear when "taxon search" is chosen. After selecting the desired taxon, the list of items matching the criteria appears on the left side of the page. Selecting "taxon search" prior to each action resets all taxa to "None selected"; selecting the back arrow browser menu bar leaves previous searches intact. The four levels of taxa appear independently of one another; e.g., names of species from an unrelated order, family, genus, and common name may be listed at the same time.

Search Results Page

For each taxon, the information is organized into six categories: illustrations, meristics, life history, ELH description, distribution, and literature. There are also links that lead directly to further information and data for this taxon on other websites.

Illustrations - For each taxon, if available, illustrations of the following life history stages are presented: egg, yolk sac, preflexion, flexion, postflexion, and either a transforming or early juvenile. Sources for these illustrations include those previously published and originals drawn from specimens in our collections; collection data are provided for unpublished original illustrations (Table 17). Original measurements of larvae are in millimeters and given in standard length (SL) unless otherwise noted. Some measurements taken from the literature are expressed as head length (HL) (Macrouridae), body length (BL), notochord length (NL), or total length (TL). The majority of illustrations are from Matarese et al. (1989), but new and revised figures have been added throughout to reflect the more recent taxonomic literature.

Meristics - For each taxon, if available, minimum, modal, and maximum counts are given for the following meristic characters: vertebrae (total, precaudal, and caudal), upper gill rakers, lower gill rakers, branchiostegal rays, caudal-fin rays (upper secondary, upper principal, lower principal and lower secondary), pelvic fin (spines and rays), pectoral-fin rays, dorsal fin (spines and rays) and anal fin (spines and rays). Unknown meristic counts are denoted with an 'X'. Data are from Matarese et al. (1989), updated from recent taxonomic works such as Moser (1996) and Busby (1998).

Life History - For each taxon, if available, data for the following life history features are presented: General (geographic range, ecology, ELH pattern, and longevity) and Spawning (area, season, mode, fecundity, age at maturity, and migration). Sections are blank if data are unknown. Data are from Matarese et al. (1989), Moser (1996) and Matarese et al. (2003), in part.

ELH Descriptions - For each taxon, a description of the eggs and larvae is provided along with pigment and/or morphological diagnostic characters for distinguishing them from similar-looking species. If available, data for the following ELH features are presented: Egg (diameter, number and size of oil globules, yolk, chorion, and pigment on yolk and embryo) and Larvae (hatch size, preanal length, flexion length, length at transformation, sequence of fin development, and larval pigment pattern). Sections are blank if data are unknown. Descriptions are from Matarese et al. (1989), and Moser (1996), in part.

Distribution - This page is composed of three maps for each taxon: a larval distribution and abundance map, an egg occurrence map, and an adult occurrence map (Matarese et al., 2003, in part). Gray squares show where samples occurred, but no individuals of a taxon were found. The sampling distribution is different among the three maps. The square grid cell is the same size on all three maps, but appears smaller on the egg and adult occurrence maps due to scale changes.

Heading -- The upper left corner of the page includes the common name of the taxon (see Robins et al., 1991). A blank indicates that no common name is available for that taxon. The upper right corner includes the name of the family in which the taxon occurs.

Larval Distribution and Abundance Map -- This map shows the quantity of larvae from combined bongo and Tucker trawl data (or neuston data for those taxa whose distribution is best described using surface gear; Table 3) in the mapped areas. The data are classified such that sampling location information and abundance are provided. Sampling location is represented by the small squares on the map. Gray squares show where sampling occurred, but no individuals of a taxon were found; colored squares show the average abundance of larvae found in the sampled area. The quantity is color coded with lighter color depicting lower and darker color depicting higher abundances. The color codes function to show general trends in the quantity of the larvae. The map is designed to show the overall abundance of the larvae, rather than the specific values of individual samples. The individual range values in the legend include the lowest value, but not the highest; the highest number marks the end of the range and is not inclusive. The user should also keep in mind that the number of samples varies greatly among the squares. An option to download distribution data is included for specific taxa as available.

Egg Occurrence Map -- Egg identification or abundance data is available for approximately 26% of those fish species for which larvae are identified in the Northeast Pacific Ocean and Bering Sea (Kendall and Matarese, 1994). Gear that is used for collecting fish eggs is biased toward planktonic individuals; demersal eggs are severely underrepresented or entirely absent from our database. Egg occurrence in this map is displayed as presence only as determined using bongo, Tucker, and neuston gears; black squares show where eggs were present when sampled. For those taxa whose eggs are demersal or unknown, the legend within the map states that eggs are not collected.

Adult Occurrence Map -- RACEBASE is a database based on adult groundfish assessment, hydroacoustic, and foreign surveys conducted by federal fishery scientists. Standard adult occurrence maps were generated with RACEBASE data that were limited to the years 1975-1998. Blue squares show where adults were found when sampled. Gray squares denote where samples were taken, but no individuals of that taxon were found. Adult occurrence maps generated with alternative data are identified with an asterisk in the legend on individual taxon pages (Matarese et al., 2003). Adult occurrence maps generated with alternative data other than RACEBASE show presence only because the geographic extent of individual surveys was unknown (no gray area appears on the map).

Footnotes - A list of literature referenced specifically for each taxon is provided. General references are listed first, followed by footnotes, and sources for figures. Choosing the "citations" tab on the gateway page also provides a complete list of references.

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last updated: June 2021