Zoarcoidei

(Eelpouts and relatives)

Class Actinopterygii

Order Perciformes

Suborder Zoarcoidei

Number of families 9

Evolution and systematics

The zoarcoids, except for a few cryptic tidepool species, are a relatively obscure group of fishes of unverified affinity. On the basis of overall shape, fin structures, and position, and their ecological preference for living on sea bottoms in cold water, the most primitive family of zoarcoids, the ronquils, (Bathymasteridae) are thought to be close to the Antarctic "cods" or icefishes (suborder Notothenioidei). The zoarcoids and notothenioids share several important anatomical features, such as having only a single pair of nostrils, females with one ovary, lacking a gas bladder, and in having many similar skull characteristics. But they differ in other skull features and in the head sensory canal system slightly.

The time of appearance of the zoarcoids is unknown. Only the ear stones (otoliths) of an Upper Pliocene (3.2 to 1.9 million years ago) eelpout from southern California are known for the entire suborder's fossil record, and that species, Lycodes pacificus, is extant. If the zoarcoids are indeed related to the notothenioids, then we might construct an evolutionary scenario like this: In their 1966 classification of teleost fishes, Humphry Greenwood and colleagues noted that by the Eocene (57 to 35 million years ago), or possibly earlier (the view now taken by more evidence), marine inshore fish faunas had become composed of the groups that make up today's faunas. Sea floor spreading along tectonic plate boundaries separated Antarctica from Australia at the close of the Eocene, and for about the next 15 million years Antarctica drifted to its present position. As the Drake Passage deepened a circumpolar current, the Antarctic Polar Front, developed lying between latitudes 50° and 60° south, isolating Antarctica climatically. This spurred the creation of its ice cap and frigid sea temperatures. The notothenioids subsequently diversified rapidly here. This implies that prior to the Eocene, an ancestral group common to both zoarcoids and notothenioids split into two subgroups that developed physiological adaptations to the cold. One of these radiated throughout the Northern Hemisphere (zoarcoids) and the other across the cold Southern Hemisphere (notothenioids and the more primitive sandperches). Later re-invasions also took place, such as by deep-sea eelpouts (Zoarcidae) into the Southern Hemisphere and sandperches (Pinguipedidae) into the tropics.

As of 2002, science recognizes about 325 species of zoarcoids in about 100 genera and nine families, although further taxonomic work is needed and new species are discovered almost every year. Three families, the quillfish (Ptilichthyidae), the prowfish (Zaproridae), and the graveldiver (Scytalinidae) have only one species. Four of the familes are very small, with 6–7 ronquils (Bathymasteridae), five wolffishes (Anarhichadidae), four wrymouths (Cryptacanthodidae) and 14 gunnels (Pholidae). Thus only two families are sizeable, with 20% of all zoarcoids in the family Stichaeidae (pricklebacks) and 70% in the Zoarcidae (eelpouts).

An analysis of the relationships within Zoarcoidei has never been published. The ronquils were seen to be the most primitive family in having no advanced features common among the other families. The gunnels and graveldiver share a common, elongate shape and have lost the pleural ribs. Pricklebacks, gunnels, and the graveldiver have characteristic elongated crania not shared by the other families except for a few advanced eelpouts. However, many of the primitive pricklebacks, particularly the subfamily Stichaeinae, have many similarities to ronquils. The prowfish and wolffishes have similar shapes, large body size, fin structures, and features of the skeleton except for the skull and may be just generally primitive zoarcoids that split off the main lineage early in the group's evolution at two different stages. Finally, the bizarre quillfish is so highly modified that its relationships are obscure. It is an extremely elongated fish (over 230 vertebrae) with many modifications of the head and fin structures and may represent another early offshoot of the main lineage that became highly modified rapidly, unlike the prowfish and wolffishes.

Physical characteristics

Two basic body shapes exist among zoarcoids. Primitively, a somewhat elongated, torpedo-like shape characterizes ronquils, some pricklebacks, wolffishes, and the prowfish; however, most pricklebacks and the wolffish Anarrhichthys ocellatus have attained a much elongated eel-like shape. All the eelpouts, gunnels, wrymouths, graveldiver, and the quillfish are eel-like in shape. Some eelpouts, especially the genus Lycenchelys and the quillfish are extremely elongated.

Most zoarcoids are small fishes reaching lengths of less than 15.8 in (40 cm). Some eelpouts attain 23.6 in (60 cm), and the largest of these, Zoarces americanus, reaches 46.5 in (118 cm). Other "giants" among the zoarcoids are the prowfish, reaching just over 3.3 ft (1 meter), and the wolffishes Anarhichas spp., reaching 47–57 in (120–145 cm), and Anarrhichthys ocellatus, the largest zoarcoid, which reaches 80 in (203 cm).

Deep-living, bottom-dwelling zoarcoids are rather somber in color, exhibiting more or less uniform shades of gray, brown, black, or purplish. Shallow-dwelling species can be more colorful, such as the prickleback genus Chirolophis, with shades of red, orange, and yellow, the ronquil genus Rathbunella, with its beautiful yellow and blue anal fin, and most of the gunnels, which show shades of green and brown to red reflecting the colors of the seaweeds among which they live. The dwarf wrymouth, Cryptacanthodes aleutensis, is uniformly red, and some North Pacific eelpouts, such as Andriashevia aptera and Puzanovia rubra, have also evolved this red to pinkish coloration. Sexual differences in coloration either do not exist or are usually subtle, with spawning males having dark anal fins, as in some gymneline eelpouts. However, the male prickleback, Opisthocentrus ocellatus, is normally drab grayish with dark markings but turns red with darker variegations in the spawning season.

Distribution

Ranges of the various zoarcoid groups can be confusing, especially in attempting to understand the pricklebacks and eelpouts; thus it is best to examine distributions on a family basis.

Bathymasteridae (ronquils): Central Sea of Japan, around the North Pacific rim to northern Baja California, Mexico.

Zoarcidae (eelpouts): In the Pacific from the northern Yellow Sea, east around the Pacific rim to the tip of South America and across the Scotia Arc to Antarctica. Four species are known from deep water in the tropical western Pacific. Distributed throughout the Arctic, especially the genera Gymnelus and Lycodes (Lycodes frigidus has been photographed in the Chukchi Sea at 78°28'N at a depth of 1.7 mi (2,653 m) and is probably widespread under the polar ice cap in suitable habitats). They live in the Atlantic from the Arctic south along the eastern United States to the Gulf of Mexico and Caribbean Sea; a few species are known from the Mid-Atlantic Ridge at hydrothermal vents. They also live in the eastern Atlantic from northern Europe, along the west African coast to South Africa. A few species of the deep-water genus Pachycara are known from the northern Indian Ocean abyss and may be widespread there. A few species of the mesopelagic genera Lycodapus and Melanostigma are circumpolar in sub-antarctic waters but do not reach coastal Antarctica, which has an endemic eelpout fauna.

Ptilichthyidae (quillfish): Hokkaido Island, Japan, around the North Pacific rim to central Oregon, United States.

Zaproridae (prowfish): Hokkaido Island, Japan, around the North Pacific rim to San Miguel Island, California.

Anarhichadidae (wolffishes): In the Pacific from Hokkaido, Japan, to the eastern Bering Sea (Anarhichas lupus) and the eastern Bering Sea to off southern California (Anarrhichthys ocellatus). In the Atlantic (three species of Anarhichas) from Massachusetts to southern Greenland and east to the Kara Sea. The American wolffish, Anarhichas lupus, reached as far south as New Jersey in the nineteenth century.

Cryptacanthodidae (wrymouths): In the Pacific throughout the Sea of Japan north to Sakhalin Island, Russia (Cryptacanthodes bergi); northern California to the Bering Sea (C. aleutensis and C. giganteus). In the Atlantic from New Jersey to Labrador (C. maculatus).

Stichaeidae (pricklebacks): In the Pacific from the northern Yellow Sea around the North Pacific rim to Baja California, Mexico. In the Atlantic from Massachusetts to Iceland, northern Norway, Britain, and throughout the Baltic Sea. A few species enter the Canadian Arctic; Lumpenus medius is circumpolar and even reaches the Sea of Japan.

Pholidae (gunnels): In the Pacific from the Yellow Sea around the North Pacific rim to Guadalupe Island, Baja California, Mexico. In the northwestern Atlantic from Delaware to Hudson Strait and the northeastern Atlantic from southern France to the Kara Sea including Iceland and Jan Mayen Island.

Scytalinidae (graveldiver): Central California (San Luis Obispo County) north to the Aleutian Islands, Alaska.

Habitat

The zoarcoids inhabit a wide variety of ecological niches and some have adapted to rather extreme habitats. At one end of this spectrum several gunnels, pricklebacks, and the graveldiver are found above the high tide line in rock pools with broad daily variation in temperature and salinity. Graveldivers also can be found burrowing in sand or gravel beaches above the surf wash. Most gunnels and pricklebacks are found in rocky areas with growths of seaweeds or invertebrate colonies, where they keep well hidden by day. In the opposite extreme many eelpouts are abyssal, or found on the bottom of the

world's ocean basins, at depths of more than 4,375 yd (4,000m). The deepest catch of a zoarcoid is that for a specimen of the eelpout Lycenchelys antarctica, trawled at 5,818 yd (5,320m) in the Peru–Chile Trench by Russian researchers. Most eelpouts inhabit continental slopes of the North Pacific and North Atlantic, where bottom temperatures are below 44.6°F (7°C). Two eelpout genera, Lycodapus and Melanostigma, have adapted to a deep-water, free-swimming habit (in the mesopelagic zone), but have been photographed near the bottom. The ronquils are generally found in rocky reefs from inshore to about 301 yd (275 m). Nowhere very abundant, they are mostly seen by scuba divers in calm waters either in the rocks or over sandy patches. The wrymouths are mud burrowers and may be more active at night than in the day. The three Pacific wrymouths are found only in moderately deep water 33–383 yd (30–350 m), but the Atlantic species may be found in intertidal areas. The Atlantic wolffishes (genus Anarhichas) occur in rocky areas, never over muddy bottoms, generally on the outer shelf 109–328 yd (100–300 m), although the American species, A. lupus, has been seen in tide-pools. The maximum depth is around 503 yd (460 m), although the three Atlantic species generally occur shallower to the north of their ranges. The Pacific wolffishes, Anarhichas orientalis and Anarrhichthys ocellatus, also occur in rocky reefs usually not deeper than 164 yd (150 m). All the wolffishes seem to lurk about in crevices and under overhangs when not foraging, sometimes in more open areas. The prowfish mostly occurs over soft bottoms of the outer shelf, but juveniles have been collected as shallow as 11 yd (10 m). One prowfish was caught in a trawl at 738 yd (675 m). Juvenile prowfish often occur in midwater where they may linger. The adult quillfish's habitat is probably free-swimming just above the bottom in outer shelf waters by day then migrating into surface waters at night to feed. One researcher speculated that it may burrow in mud, but without direct evidence.

Behavior

Most zoarcoids are cryptic and solitary throughout their lives, but may congregate in shelters or around food sources temporarily. Some deep-sea eelpouts have been photographed gathering around mammal carcasses and baited traps to feed on the amphipods that devour the carcass or bait. Some gunnels are known to share rock crevices for shelter. Social organization is not well documented in these hard-to-observe fishes. What behavioral patterns are known exist mostly as notes in the scientific literature from aquarium or scuba observations focusing mainly on reproduction. Nest guardianship has been noted for a few ronquils, pricklebacks, gunnels, eelpouts, and the wolf-eel, and this is discussed in the next section. During the winter in higher latitudes intertidal zoarcoids migrate into deeper water to avoid freezing, but populations are very localized and no great migrations occur. Thus, population movements are solely through larval dispersal by nearshore currents. Territoriality, as far as known, is probably weak among established adults of nearshore zoarcoids, since many share close spaces, but nothing is known of this in the deeper-living, cryptic species.

Feeding ecology and diet

The vast majority of zoarcoids are grazing predators of small invertebrates such as worms, crustaceans, molluscs, and echinoderms. Many switch prey items by season or as they age, but a significant number are dietary specialists, a situation often localized for a particular species. No in-depth study of the biology of the ronquils has been undertaken. Postlarvae (0.2–0.4 in [5–11 mm] in length) of Ronquilus jordani in southern British Columbia had been feeding near the surface on crustaceans (Cladocera, Copepoda, Cirrepedia larvae), clam larvae, and polychaete worms. The stripedfin ronquil, Rathbunella hypoplecta, is known to feed on the bottom primarily on crustaceans, but fish in one sample had fed exclusively on sea slugs (nudibranchs). A nest-guarding male R. hypoplecta had cannibalized part of his brood. Adult ronquils, then, are probably all opportunistic bottom grazers. The diets and feeding habits of a few eelpouts have been studied. Bottom-living species rely on crustaceans, particularly amphipods, but also eat smaller fishes, sea snails, clams, other kinds of crustaceans and, to a lesser extent, brittle stars and polychaete worms. The diets of the mesopelagic eelpouts Lycodapus mandibularis and Melanostigma pammelas off California diversify with increasing size but mainly consist of a few kinds of crustaceans. Young pricklebacks of several species in the water column off British Columbia feed on copepods and clam larvae. As they grow and settle into bottom habitats, a dietary shift occurs and most adult pricklebacks then rely on polychaetes, amphipods, sea snails, nudibranchs, various kinds of algae, bryozoans, shrimps, crabs, and sponges. Although this appears to be a rather diverse diet when several species are examined from different areas, many of the xiphisterine pricklebacks are herbivores, eating only a few kinds of red and green algae. Atlantic pricklebacks have been recorded with similar diets: amphipods, copepods, ostracods, brittle stars, clams, sea cucumbers (Holothuria) and polychaetes. Gunnels, living among rocks and seaweeds with pricklebacks, feed on the same prey. The Atlantic butterfish, Pholis gunnellus, eats various mollusks,

especially sea snails, crustaceans, and polychaetes, and has been known to raid other fishes' nests to consume their eggs. In the Canadian Pacific, Pholis ornata and Pholis laeta are known to switch diets with age. Both mostly rely on harpacticoid copepods when young, but large fish shift mostly to caprellid amphipods (P. laeta) or clam siphons (P. ornata). Young wrymouths in the Canadian Pacific also rely on copepods when feeding in midwater. The diets of adults are not well recorded, but food recorded for the Atlantic wrymouth consists of various crustaceans, mollusks, and fish. The wolffishes all have canine teeth in the front of their jaws and viselike molars in the back, dental adaptations for dealing with hard-shelled prey. The Atlantic wolffishes prey on mollusks like whelks, cockles, clams, and mussels as well as large crabs, hermit crabs, starfish, and sea urchins, the latter rather formidable as food. The Pacific wolf-eel, Anarrhichthys ocellatus, eats mostly commercial crabs (Cancer magister) and other hard-shelled invertebrates. Fish rarely enter the diets of wolffishes. Not much is known of the food habits of the prowfish, graveldiver, or quillfish. Young prowfish are free-swimming and are known to associate with jellyfish. Remnants of amphipods that also associate with jellyfish, as well as jelly fragments, have been found in stomachs of large prowfish. Thus they may utilize various jellyfishes as a food source, at least in part, throughout their life. Graveldivers are burrowers and probably hunt tiny interstitial invertebrates. The quillfish, with its small, upturned mouth and free-swimming habits, probably preys on a variety of small planktonic crustaceans and mollusc larvae.

Reproductive biology

Because nearshore zoarcoids are generally small, cryptic fishes and offshore species usually live beyond scuba depths, almost all observations on the reproductive biology of these fishes come from aquarium observations on a few nearshore species. A few zoarcoids captured from scientific research vessels have been examined in some detail, but generally little about their reproduction is known.

Direct observations on courtship are few, and fertilization is internal in all known bottom-living species. Males of the elongate zoarcoids (eelpouts, gunnels, pricklebacks, wolf-eel) wrap around receptive females snake-like and fertilization is internal, or eggs are fertilized as they are laid in clusters. The pectoral fins in courting male viviparous eelpouts (Zoarces viviparus) turn bright red and males assume a characteristic coiled position with the fins outstretched. When females are receptive males then assume a transverse position under and alongside the female for mating. Pelagic eelpouts like Lycodapus may have little formal courtship behavior and probably just pair up during a protracted spawning season and release eggs and milt into the water column. The northern ronquil (Ronquilus jordani) has a rather long courtship with the male displaying to the female with body and fin quivering and fanning. It is generally assumed that most of the nearshore zoarcoids spawn during daylight hours when they can see one another for courting, but the Japanese tidepool gunnel (Pholis nebulosa) courts and spawns from about midnight to dawn.

Egg size and number vary greatly in zoarcoids, owing to the variation in adult body size. Reported sizes range from about 0.1–0.3 in (1–7 mm), but the eggs of the quillfish, graveldiver, and prowfish are unknown. Fecundity ranges from less than 20 eggs per female in some primitive eelpouts (Gymnelinae) to about 50,000 in one wolffish. Eggs can be clear, white, yellowish, or orange with oil droplets usually yellow, orange, or red, and most are adhesive since they are laid in nests. Incubation times range from about two weeks to three months. Yolk sac larvae of bottom-living zoarcoids generally stay near the bottom, but some become planktonic for anywhere from a few seconds to minutes (Zoarces americanus), or up to two years (Anarrhichthys ocellatus).

Nests are generally simple hideaways among most zoarcoids. Ronquils lay loose egg masses on flat surfaces, which are fanned and usually guarded by the male. In the stripedfin ronquil (Rathbunella hypoplecta), there is an aquarium observation of a female laying eggs six times every two weeks for a total of about 10,000 eggs during the three months. A new clutch was laid just days after the most recent spawn hatched, and the male guarded the egg mass. Bottom-living eelpouts excavate a crater in muddy bottoms and coil around a clump of eggs. However, the Atlantic midwater eelpout (Melanostigma atlanticum) is known to burrow tunnels into soft muddy bottoms with a male and female spawning, but sometimes several apparently non-spawning individuals may occupy the tunnels to help circulate water in this anoxic environment. Gunnels and pricklebacks lay eggs on seaweeds (Zostera, some algae) or in nests in rock crevices and holes; some gunnels are known to use empty oyster or mussel shells. Wolffishes build nests in rocky shelters or lay their eggs among seaweeds and stones.

Parental care is fairly limited in most zoarcoids that are known for this behavior. The male of the smooth ronquil noted above sometimes ate some of the eggs he was guarding. Guardianship of nests may be limited to fanning with charging displays against intruders (ronquils) or of parents holing up with the eggs with no overt signs of care simply because the nest area provides good cover (gunnels and pricklebacks).

The spawning season of zoarcoids can be short, just a few months between courtship and egg hatching, or protracted into the better part of a year. Some deep-sea eelpouts spawn only once or twice at the end of their lives, and seasonality may not exist for these. Ronquils and many gunnels and pricklebacks spawn from the spring to summer; other gunnels and pricklebacks are autumn to winter spawners. The North Atlantic wolffishes spawn from spring to winter, and the more northerly populations start earlier in the year than southern populations. The northwestern Atlantic wrymouth (Cryptacanthodes maculatus) is a winter spawner, but the Japanese wrymouth (Cryptacanthodes bergi) spawns from spring to summer. On the basis of larval captures in scientific collecting nets, quillfish spawn at least in spring but probably have a longer season. Nothing is known of the spawning habits of the prowfish or graveldiver.

Conservation status

Most nearshore zoarcoids are fairly common in their preferred habitats. This includes most ronquils, gunnels, pricklebacks, shallow-dwelling eelpouts, and wolffishes where they're not fished. Other species are rare, and this is a result of either naturally low population densities or that they are rarely caught or seen, such as the graveldiver, prowfish, and quillfish. No zoarcoids have been considered endangered or threatened, mostly owing to these fishes' usually cryptic habits and limited commercial use.

Significance to humans

The zoarcoids are a fairly insignificant group of fishes in human history. No mythology or significant art or literature exists, but it is interesting to note that in the Middle Ages it was commonly held that the European viviparous eelpout (Zoarces viviparus) was said to birth all eels (order Anguilliformes), owing to its live-bearing mode of reproduction. Significant fisheries do not exist for any zoarcoid today. However, after World War II a minor longline fishery for wolffishes (Anarhichas) developed across the North Atlantic, but catches have declined dramatically since. An unsuccessful attempt was made to develop a fishery for the American ocean pout (Zoarces americanus) after World War II, but natural parasitic infections in the flesh quickly killed the plan. No zoarcoid poses any real danger to humans except wolffishes. Trawl-caught Anarhichas species have been known to snap at fishermen and a large, speared wolf-eel (Anarrhichthys ocellatus), because of its strength and imposing teeth, may inflict serious bites to careless scuba divers.

Species accounts

List of Species

Wolf-eel

Anarrhichthys ocellatus

family

Anarhichadidae

taxonomy

Anarrhichthys ocellatus Ayres, 1855, San Francisco, California.

other common names

English: Pacific wolfeel.

physical characteristics

Body eel-like. Dorsal and anal fins long and low, continuous with a small caudal fin. Pectoral fins large and fan-like. Pelvic fins absent. Background color blue, greenish, brown, or gray-brown. The body and head are covered with white-lined black spots. Scales are small and rounded and embedded in the skin. There is no lateral line canal. The teeth in front are canine-like, and the rear teeth are molar-like. Juveniles are orangish brown, with spots more numerous and larger than in adults; the spots sometimes form into stripes. This is the largest zoarcoid, reaching 2.2 yd (203 cm).

distribution

Southeastern Bering Sea to off Imperial Beach, California. Records for the Sea of Japan or Kamchatka are erroneous.

habitat

Deep rocky reefs in caves or crevices. Juveniles are free-swimming for an extended period.

behavior

Cryptic and solitary or lives with an apparent life-long mate in a den. It is a dusk and dawn predator but also feeds during the day. Territorial disputes occur with large individuals displacing mated pairs occasionally.

feeding ecology and diet

Stalking predator. Feeds mainly on hard-shelled invertebrates and occasionally fish. Wolf-eels grab their prey with their enlarged canines and crush it with their rear molars. Known prey consists of crabs, clams, mussels, sea urchins, sand dollars, snails, and abalone. A population of wolf eels at the head of the Monterey submarine canyon in California has relied on sand dollars at least seasonally, a food presumably rather low in nutrition for its bulk. Free-swimming juveniles eat plankton and small fish.

reproductive biology

Pairs form at about four years of age (length about 3.3 ft [1m]), and eggs are first laid at about seven years. Spawning occurs from October to February. Courtship consists of the male repeatedly bumping the female's abdomen; when she is receptive he coils around her snake-like. Eggs are fertilized as they are laid in clumps of about 7,000–10,000, and the female gathers these up into a ball and wraps around them, occasionally turning them for aeration. Both parents guard the nest, and only one at a time leaves to forage. Hatching occurs at 13–16 weeks, depending on water temperature. Juveniles are free-swimming for up to two years, then settle on open bottom until they take up their sedentary den life.

conservation status

Not threatened. This species is common and widespread along its range. A minor fishery exists among scuba divers, skiff fishermen, and bottom trawlers.

significance to humans

The wolf-eel is a good eating fish, and the scuba and small boat fishery has been significant and sustained in some areas of central California and Puget Sound, Washington. Wolf-eel teeth have been found in a native American village site in central California, indicating a fishery at least 9,000 years old. Tribes in the Pacific Northwest reserved this delicacy for their shamans.

Wrymouth

Cryptacanthodes maculatus

family

Cryptacanthodidae

taxonomy

Cryptacanthodes maculates Storer, 1839, off Massachusetts, United States.

other common names

English: Congo eel, ghostfish; French: Terrassier tacheté.

physical characteristics

Body eel-like. Head flattened above. Eyes small. Mouth large and up-turned. Pectoral fins small. Pelvic fins absent.

Dorsal and anal fins long, low, and continuous with caudal, which is well developed. Background color brown to reddish brown, with 2–3 irregular rows of dark brown spots or blotches running from head to tail. The dorsal and anal fins have rows of smaller brown spots. Abdomen pale gray. Scales absent.

distribution

Southern Labrador south to New Jersey.

habitat

Found from just above the low tide mark (the intertidal zone) to almost 656 yd (600 m). Constructs branching tunnels in riverine mudflats, where it lives singly. May live in burrows or hide in crevices or under rocks in deeper water.

behavior

Due to their secretive burrowing habits, there have been no observations on natural behavior. One wrymouth was kept in an aquarium, where it could not burrow. It lived instead in a piece of rubber tubing. Thus it is likely that they hide almost all the time and venture forth only to forage.

feeding ecology and diet

Grazing or ambush predator. Feeds on small crustaceans (amphipods, shrimps, and hermit crabs), mollusks (limpets, sea snails, clams, and mussels), and occasionally fishes.

reproductive biology

Eggs and larvae are unknown, but wrymouths undoubtedly spawn on the bottom and probably guard nests. Fry have been collected in scientific sampling nets in early spring, indicating winter spawning.

conservation status

Rarely seen. Not threatened.

significance to humans

None known.

Saddleback gunnel

Pholis ornata

family

Pholidae

taxonomy

Gunnellus ornatus Girard, 1854, San Francisco, California.

other common names

None known.

physical characteristics

Body eel-like. Pectoral fin small and half as long as the head. Pelvic fins are minute, mere splints. Dorsal and anal fins continuous with a caudal, which is well developed. Color can change from olive-green to brown dorsally; abdomen yellow to reddish. There is a dark bar under the eye and two above the eye across the head. There are several (about 13–15) U-shaped or V-shaped markings ("saddles") along the base of the dorsal fin reaching onto it. No lateral line canal. Scales minute, rounded, and embedded in the skin.

distribution

Northern Vancouver Island, British Columbia south to Carmel, California.

habitat

Migrates seasonally from brackish, estuarine mudflats and subtidal sea grass beds under rocks in autumn to deeper water out to about 44 yd (40 m), where its major competitor, Pholis laeta, occurs. Where that species does not co-occur with the saddleback, some remain in the intertidal zone year-round. The young settle in the rocky intertidal or shallow channels in winter and move into more brackish water later.

behavior

Solitary and cryptic. Aggregates for spawning. Probably not territorial.

feeding ecology and diet

Grazer. Dietary shifts correlated with age. In British Columbia the young feed mainly on small crustaceans (copepods) and polychaete worms, while older fish switch to clam siphons, relying less on small crustaceans (copepods and tanaids).

reproductive biology

Spawns in rocky intertidal or deeper sea grass beds under rocks in winter. There is probably a single spawning of one male and one female; both parents guard the eggs. Larvae are pelagic for a brief period and settle in rocky intertidal areas then move into brackish mudflats with seasonal growth of seaweeds, at least in bays and estuaries.

conservation status

Not threatened. Common and widespread along its range. It is cryptic and rarely encountered by humans.

significance to humans

Because of its secretive habits and small size, there has never been a fishery for the saddleback gunnel, and it does not make a good aquarium fish. Thus the species has been of little significance to humans.

Black prickleback

Xiphister atropurpureus

family

Stichaeidae

taxonomy

Ophidium atropurpureum Kittlitz, 1858, Alaska (no specifics). Correct generic placement should probably be in Xiphidion Girard, 1858 (or 1859), pending further research.

other common names

None known.

physical characteristics

Body eel-like. Pectoral fins are minute, of only 11 or 12 rays. Pelvic fins absent. Dorsal and anal fins continuous with caudal, which is well developed and has a whitish band at its base. Color reddish brown to black; abdomen is lighter. Head has three broad, black eye bars with whitish borders. Scales are minute, rounded, and covered with skin.

distribution

Kodiak Island, Alaska south to Baja California Norte, Mexico.

habitat

Intertidal zone in rock pools among seaweeds and in crevices out to about 32.8 ft (10 m). Also found under wharf pilings and in boat harbors where shelter (human trash usually) can be found.

behavior

Solitary and cryptic without territoriality. Parental care of the eggs occurs (see below).

feeding ecology and diet

Omnivore. Feeds on seaweeds and invertebrates on or associated with the bottom, primarily crustaceans, worms, and sea

snails. Hatchlings caught in surface-towed nets in British Columbia had been feeding on copepod crustaceans and clam larvae but probably eat any small planktonic animals.

reproductive biology

Spawning occurs from winter to spring throughout the range, under rocks along protected pebbly or shelly beaches in winter and shifting to other beaches that are more exposed in spring. Females lay about 900–1,700 eggs about 0.1 in (2 mm) in diameter, and males guard the site. Males may spawn with more than one female. Territoriality is non-existent in that several males may congregate under the same rock, and sometimes other species, such as clingfishes, are found nearby. Hatchlings are about 0.3 in (8.5 mm) long, and metamorphosis occurs at about 0.7 in (18 mm) when they become free-swimming and feed on small plankton.

conservation status

Not threatened. Common and widespread along its extensive range. It is cryptic and rarely encountered by either humans or predators.

significance to humans

Owing to its secretive habits and small size there has never been a fishery for the black prickleback, and it does not make a good aquarium fish; thus the species has been of little significance to humans.

Ocean pout

Zoarces americanus

family

Zoarcidae

taxonomy

Blennius americanus Bloch and Schneider, 1801, American seas.

other common names

English: Muttonfish, yowler; French: Loquette d'Amérique.

physical characteristics

Body eel-like but rather stout in adults. Pectoral fins large and fan-like. Pelvic fins have short splints. The dorsal and anal fins are continuous with the caudal fin; the dorsal fin has about 15–25 tiny spines at its rear. Background color usually muddy yellowish, tinged with brown above and becoming darker with age. Belly usually yellowish but can be olive-green. Mottling on the sides is brown, but the pattern is individually variable. Teeth are green in northern populations owing to predation on sea urchins. Scales are minute, round, and not overlapping.

distribution

Southern Labrador south to Virginia.

habitat

Adults found on the outer shelf to about 219 yd (200 m) on sandy or muddy bottoms. Young may come into intertidal areas among seaweed and rocks. Free-swimming hatchlings sometimes found in estuaries of large rivers to the north.

behavior

Very little is known of behavioral traits in ocean pout, mostly owing to the difficulty of observing them in their usual offshore habitat. Based on aquarium observations, they probably live passive, solitary lives without territories and seem only to congregate for spawning. Spawning consists of several copulations over many hours. Large spawning males are aggressive to smaller males at this time, as are females with non-spawning females. Parental care of the eggs occurs (see below).

feeding ecology and diet

Grazer. Feeds on invertebrates on or within the sea floor, mostly on crustaceans (amphipods, Cancer crabs, and hermit crabs especially), sea urchins, worms, bivalves (clams and scallops), sea snails, and brittle stars. Fish found in a few stomachs occasionally are probably scavenged.

reproductive biology

Spawning occurs in early to mid-Autumn and consists of males approaching ripe females and rolling on their sides or even upside down under the female. Fertilization is internal and several copulations occur for 2–3 minutes each over many hours, perhaps up to half a day. Egg laying occurs around 6–17 hours after the last copulation. Large females lay a clutch of eggs in rocky areas more numerous than smaller females. A female at nearly 35.4 in (90 cm), near the maximum size, contained over 4,100 ripe eggs; another at 21.6 in (55 cm), and probably spawning for the first or second time, had 1,300 eggs. The eggs are pale yellow and measure 0.24–0.28 in (6–7 mm) in diameter. Upon laying her egg mass the female fans and wipes her skin over the eggs for around 30 minutes. This coats the mass in an antibiotic mucus. Then the female wraps herself tightly around the mass (now white in color), which helps stick it together into an egg ball. Females remain passive while guarding their eggs except for intermittent swimming in circles while fanning the eggs with their pectoral fins. Incubation lasts for three months, during which females probably do not feed much. Fry hatch in mid-winter, and yolk sac resorption occurs in seconds. Fry have a very short planktonic phase while working their way inshore, where they develop over the first few years of their lives.

conservation status

Not threatened. Common in nearshore environments as young where predation is probably low. Also common offshore even on the fishing banks off New England and Nova Scotia.

significance to humans

A minor fishery for ocean pout began in Massachusetts in the 1930s, with fish being sold "round" in Boston markets. In 1943, as a war effort, a concerted attempt was made to sell whole fillets, and landings reached almost 4.4 million lb (2 million kg) in 1944. However, ocean pout are afflicted with a microsporidian (Protozoa) parasite that produces unsightly lesions in the flesh. Landings dropped to under 6,100 lb (2,767 kg) by 1948, and the fishery subsequently failed. Attempts to revive the fishery in the 1970s also failed.

Resources

Books

Andriashev, A. P. Fishes of the Northern Seas of the USSR. Moscow: Academy of Sciences, USSR, 1954.

Bigelow, H. B. and W. C. Schroeder. Fishes of the Gulf of Maine. Washington, DC: U. S. Fish and Wildlife Service, 1953.

Breder, C. M., Jr. and D. E. Rosen. Modes of Reproduction in Fishes. Jersey City: T.F.H. Publications, 1966.

Burgess, W. E. and H. R. Axelrod. Fishes of California and Western Mexico. Neptune City, NJ: T.F.H. Publications, 1984.

Eschmeyer, W. N. and E. S. Herald. A Field Guide to Pacific Coast Fishes of North America. Boston: Houghton Mifflin, 1983.

Fitch, J. E. and R. J. Lavenberg. Tidepool and Nearshore Fishes of California. Berkeley: University of California Press, 1975.

Goodson, G. Fishes of the Pacific Coast. Stanford: Stanford University Press, 1988.

Hart, J. L. Pacific Fishes of Canada. Ottawa: Fisheries Research Board of Canada, 1973.

Kiernan, A. M. Systematics and Zoogeography of the Ronquils, Family Bathymasteridae (Teleostei: Perciformes). Seattle: University of Washington, Ph.D. Dissertation, 1990.

Leim, A. H. and W. B. Scott. Fishes of the Atlantic Coast of Canada. Ottawa: Fisheries Research Board of Canada, 1966.

Masuda, H. et al., eds. The Fishes of the Japanese Archipelago. Tokyo: Tokai University Press, 1984.

Mecklenburg, C. W., T. A. Mecklenburg, and L. K. Thorsteinson. Fishes of Alaska. Bethesda: American Fisheries Society, 2002.

Nawojchik, R. A Systematic Revision of Zoarcoid Fishes of the Family Cryptacanthodidae (Teleostei: Perciformes). Seattle: University of Washington, M.S. Thesis, 1986.

Whitehead, P. J. P. et al., eds. Fishes of the North-eastern Atlantic and the Mediterranean. Vol. 3. Paris: United Nations Educational, Scientific, and Cultural Organization, 1986.

Wingert, R. C. Comparative Reproductive Cycles and Growth in Two Species of Xiphister (Pisces, Stichaeidae) from San Simeon, California. Fullerton: California State University, M. A. Thesis, 1974.

Periodicals

Anderson, M. E. "Systematics and Osteology of the Zoarcidae (Teleostei: Perciformes)." Smith Institute of Ichthyology, Bulletin 60 (1994): 1–120.

Barsukov, V. V. "Fauna of the USSR. Fishes. Family Zubatok (Anarhichadidae)." Zoological Institute, Academy of Sciences, USSR 5, no. 5 (1959): 1–171.

Barton, M. "Comparative Distribution and Habitat Preferences of Two Species of Stichaeoid Fishes in Yaquina Bay, Oregon." Journal of Experimental Marine Biology and Ecology 59 (1982): 77–87.

Hughes, G. W. "The Comparative Ecology and Evidence for Resource Partitioning in Two Pholidid Fishes (Pisces: Pholididae) from Southern British Columbia Eelgrass Beds." Canadian Journal of Zoology 64, no. 1 (1985): 76–85.

Marliave, J. B. "Seasonal Shifts in the Spawning Site of a Northeast Pacific Intertidal Fish." Journal of the Fisheries Research Board of Canada 32, no. 10 (1975): 1687–1691.

——. "The Life History and Captive Reproduction of the Wolf-Eel at the Vancouver Public Aquarium." International Zoo Yearbook 26 (1987): 70–81.

Marliave, J. B., and E. E. DeMartini. "Parental Behavior of Intertidal Fishes of the Stichaeid Genus Xiphister." Canadian Journal of Zoology 55, no. 1 (1977): 60–3.

Matarese, A. C., A. W. Kendall, Jr., D. M. Blood, and B. M. Vinter. "Laboratory Guide to Early Life History Stages of Northeast Pacific Fishes." NOAA Technical Report NMFS 80 (October 1989): 496–531.

Peden, A. E. and G. W. Hughes. "Distribution, Morphological Variation, and Systematic Relationship of Pholis laeta and P. ornate (Pisces: Pholididae) with a Description of the Related Form P. nea n. sp." Canadian Journal of Zoology 62, no. 2(1984): 291–305.

Richardson, S. L. and D. A. DeHart. "Records of Larval, Transforming and Adult Specimens of the Quillfish, Ptilichthys goodei, from Waters off Oregon." Fishery Bulletin 73, no. 3 (1975): 681–5.

Yao, Z. and L. W. Crim. "Copulation, Spawning and Parental Care in Captive Ocean Pout." Journal of Fish Biology 47(1995): 171–3.

Yatsu, A. "A Revision of the Gunnel Family Pholididae (Pisces, Blennioidei)." Bulletin of the National Science Museum 7, no. 4 (December 1981): 165–190.

M. Eric Anderson, PhD