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Fishes of the Northwest

 

   

Lingcod

Lingcod Life History

Lingcod ( Ophiodon elongatus ) are unique to the west coast of North America, with the center of abundance off the coast of British Columbia. They are found on the bottom with most individuals occupying rocky areas at depths of 10-100 m. Tagging studies have shown that lingcod are a largely non-migratory species, with colonization and recruitment occurring in localized areas only.

Starting in October, lingcod migrate to nearshore spawning grounds. The males migrate first, and establish nest sites in strong current areas in rock crevices or on ledges. Spawning takes place between December and March, and females leave the nest site immediately after depositing eggs. Males actively defend the nest from predators until the eggs hatch in early March through late April.  The photo to the right shows a nest-guarding male protecting his egg mass (photo by J. King).

The larvae are pelagic until late May or early June when they settle to the bottom as juveniles. Initially they inhabit eel grass beds, and eventually move to flat sandy areas that are not typical habitat of older lingcod. They eventually settle in habitats of similar relief and substrate as older lingcod, but remain at shallower depths for several years.

Females and males mature at age 3-5 years (61-75 cm) and age 2 years (45 cm), respectively. Adult males can be distinguished externally from females by the presence of a small, conical papilla behind the anal vent.   Up to age 2 males and females grow at similar rates, with both reaching an average length of 45 cm. After age 2, females grow faster than males, with the growth of males tapering off at about age 8, and females continuing to grow until about age 12-14. Lingcod live up to a maximum of about 14 years for males and 20 years for females, reaching a maximum size of approximately 90 cm and 120 cm, respectively.

Lingcod are voracious predators, feeding on invertebrates and many species of fish, including herring ( Clupea harengus ) and Pacific hake ( Merluccius productus ). Lingcod that survive the larval stages have few predators themselves, and are vulnerable mainly to marine mammals such as sea lions and harbor seals.

 

 
All images copyright Strait Scuba 2003-2012
 
 
 

 

 

 

 

Age Determination of lingcod

In 1977, Dr. Dick Beamish and Doris Chilton of the Pacific Biological Station published an article showing that cross sections of the 4 th to 8 th fin rays from the second dorsal fin provided a method for estimating the age of lingcod 1,2 . This method has since been validated by a mark-recapture study in which lingcod received an injection of oxytetracycline (OTC) 3,4 . Other methods of aging, such as those using scales and otoliths, were found to underestimate ages for older fish.

Ages are determined from fins in much the same manner as for other aging structures: sections of varying thickness are examined under a microscope, and the annuli, or rings, that are formed for each year of growth are counted and used to estimate the age. The cross sections must be made at right angles to the length of the fin ray, and it is therefore important that fins be dried flat, with the cut surface at right angles to the fin rays. In addition, the distance that the section is cut from the fin-ray base is important, and for this reason, all fins should be collected with the base intact 3,4 . One problem associated with using fin rays to age older fish, is that the fin-ray center may be resorbed, resulting in the loss of the first two annuli. It is therefore necessary to determine an average width for the first two annuli by examining the fins from juvenile fish. This measurement can then be used to estimate the position of the third annulus on older fish.

 

Kelp Greenling

 

Abbreviated Life History of Kelp Greenling

(Hexagrammos decagrammus)


The kelp greenling is in the family of Hexagrammidae and shares this taxonomic relationship with lingcod. The kelp greenling is one of the most conspicuous fishes in rocky nearshore habitats, occurring often in and around kelp beds. The male and female look so different that they were first described as separate species. The body color is variable in both sexes, ranging from light gray to brown. Males, however, have large irregular blue patches anteriorly, while females are uniformly covered with smaller dark spots.

Distribution, Stock Structure and Migration.

Populations range along the eastern Pacific coast from La Jolla, California to the Aleutian Islands in Alaska. Kelp greenlings are not known to migrate; on the contrary, adults are often territorial, particularly during spawning season.

Age and Growth

Kelp greenlings grow faster than most nearshore fishes during their first three years. They have been aged to a maximum of 8 yr for males and 13 yr for females. Total lengths corresponding to the male and female ages were 15.0 in. and 17.4 in., respectively. The largest recorded size is 21 in. TL.

Reproduction, Fecundity and Seasonality

Approximately one third of all male kelp greenling are sexually mature at age 2, while half of all males are mature by age 3-4 at an average total length of 11.6 inches. Approximately one half to two thirds of all females kelp greenling are sexually mature at age 3-4 at an average total length of 11.6 inches. In California, the spawning season for kelp greenling occurs from September through December. Females spawn their eggs subtidally on rocks. Their egg nests have been observed at depths of 16 to 56 feet. An individual male kelp greenling may guard up to 11 egg masses simultaneously, although the average number is four. Hatching occurs from December through February in northern California. Larvae are approximately 0.3 to 0.4 in. long at hatching and remain as planktonic organisms up to a total length of 2.0 to 2.7 inches.

Predator/Prey Relationships

Kelp greenling larvae prey on a wide variety of planktonic organisms, including fish larvae and eggs. During most of the year, juveniles and adults consume a variety of prey that is consistently available in the habitat, including crabs, shrimp, snails, chiton, abalones, octopi, fish, fish eggs, and algae. There are brief periods when organisms such as juvenile fishes or herring spawn become exceptionally abundant, and kelp greenling shift their food habits to take advantage of these opportunities. The primary predators of adult greenling are lingcod and harbor seal.

Competition

Based on co-occurrence with adult and juvenile kelp greenling, demersal fishes associated with kelp beds and reef structure likely to compete with kelp greenling for food and space would include lingcod, cabezon, and rockfish species such as grass, gopher, black-and-yellow, China, quillback, copper, and vermilion.

Critical Habitat

Kelp greenling range in depth from the intertidal to approximately 500 ft deep but are more common at depths of 150 ft or less. Fish frequent subtidal habitats in or around rocky reef areas and under kelp beds. Juveniles and adults both are common on any rocky bottom area with dense algal growth.

Cabezon

Abbreviated Life History of Cabezon

(Scorpaenichthys marmoratus)


The cabezon is the largest member of the cottid family. In Spanish cabezon means big-headed or stubborn, and, proportionally, the massive head is definitely the largest feature of this fish. The specific name marmoratus refers to the marbled or mottled appearance of the body, which can be reddish, greenish, or bronze.

Distribution, Stock Structure and Migration.

Populations range along the eastern Pacific coast from Point Abreojos, Baja California to Sitka, Alaska. Cabezon normally occur nearshore and their depth range extends from the intertidal to 335 ft. As fish get older and larger they tend to migrate into deeper water. In shallower water they migrate in and out with the tide to feed.

Age and Growth

Cabezon have been aged to a maximum age of 17 yr for males and 16 yr for females. Total lengths corresponding to these ages were 25.5 in. and 28.5 in., respectively. The largest recorded size is 39 in. in length and over 25 pounds.

Reproduction, Fecundity and Seasonality

Limited information available on age at sexual maturity suggests in central California males begin to mature in their third year and all are mature by their fourth year. The smallest mature male cabezon observed measured from 13.3 to 13.5 in. TL, and the smallest mature female cabezon observed measured 17.5 in. TL. Some females begin to mature in their fourth year between 15 and 20 in. in length, and by the sixth year all females are sexually mature. In California, spawning commences in late October, peaks in January and continues until March. Females are oviparous, meaning they lay or spawn eggs. Females spawn their eggs on intertidal and subtidal, algae-free rocky surfaces, primarily in crevices and under rocks. Masses of the pale green or reddish eggs are up to18 in. in diameter and up to two to four inches thick. Males fertilize the eggs after spawning by the female, and the male guards the nest during the 2-3 week period that the eggs mature. Fish are very protective of the nests for the two to three weeks it takes the eggs to develop and hatch. Larvae are approximately 0.1 to 0.2 in. long at hatching and begin to settle out of the plankton at 0.6 to 0.9 inches.

 

Predator/Prey Relationships

Cabezon can be aptly described as Asit and wait@ predators. Their mottled coloration lets them blend in with their surroundings as they sit motionless to wait for their next meal. With large, robust pectoral fins set low on the body and a powerful tail, they quickly lunge after unwary prey, engulfing it in their large mouth.

Adult fish eat crabs, small lobsters, mollusks (abalone, squid, octopi), small fish (including rockfishes), and fish eggs. Juveniles are taken by rockfishes and larger cabezon, as well as by lingcod and other sculpins.

Competition

Based on co-occurrence with adult and juvenile cabezon, demersal fishes associated with kelp beds and reef structure likely to compete with cabezon for food and space would include lingcod, greenlings, and rockfish species such as grass, gopher, black-and-yellow, China, quillback, copper, and vermilion.

Critical Habitat

Fish frequent subtidal habitats in or around rocky reef areas and under kelp beds. Usually solitary, juveniles and adults both are common on any rocky bottom area with dense algal growth. They are often in the vicinity of kelp beds, jetties, isolated rocky reefs or pinnacles, and in shallow tide pools. Most of their time is spent sitting in holes, on reefs, in pools, or on kelp blades beneath the canopy, but not actively swimming.

Status of Stocks

Limited information is available on population biology or changes in biomass over time.

Black Rockfish

Abbreviated Life History of Black Rockfish

(Sebastes melanops)


Black rockfish are a minor to moderate component of nearshore commercial and recreational fisheries, with increasing importance from the San Francisco area northward.

Distribution, Stock Structure and Migration

Black rockfish range from Amchitka Island, Alaska to Santa Monica Bay in southern California, but are uncommon south of Santa Cruz. They frequently occur in loose schools ten to twenty feet above shallow (to 120ft) rocky reefs, but individuals may also be observed resting on rocky bottoms, or schooling midwater over deeper (to 240ft) reefs to 1200ft.

Records for black rockfish show or describe a range of movement/migratory patterns from residential (no movement) to transient (movement to 345 mi.).

Age and Growth

This species may attain a maximum length of 25.5 in. in California, although individuals over 20 in. are rarely observed today. Average size observed in commercial and recreational fisheries now is 14 to 15 in. in northern California and 11 to 13 in. in central California.

Black rockfish have a relatively fast growth rate. First-year growth is usually 3.5 to 4.0 inches. Most individuals become available to the fishery by the time they have reached 3 to 4 years of age and are approximately 10 to 11.5 inches.

Reproduction, Fecundity and Seasonality

In California, age at first maturity for males is 3 yr, or 9.8 in. TL. For females, age at first maturity is 5 yr or, 11.8 inches. At 6 yr, or about 14 in., half of all males are sexually mature. At 6 to 7 yr, or about 16 in., half of all females are sexually mature.

As with all members of the genus Sebastes, fertilization and development of embryos is internal. Black rockfish mating generally occurs between September and November.

Females store the sperm internally until their eggs mature in December or January, at which time the eggs are fertilized. The larvae develop within thirty days, at which time the black eyespots become visible to the naked eye. The eyed larvae are spawned from late January to May, peaking in February off California.

Larvae are planktonic for three to six months where they are dispersed by currents, advection, and upwelling. They begin to reappear as young-of-the-year (YOY) fish in shallow, nearshore waters by May, but the major recruitment event usually occurs from July to August.

Natural Mortality

Mortality estimates have been calculated for black rockfish along the Pacific coast. The instantaneous rate of natural mortality (M) has been found to vary between 0.2 and 0.4 for unsexed fish along the Pacific coast.

Diseases

No information is available on diseases in black rockfish

Predator/Prey Relationships

As larvae, black rockfish feed on nauplii, invertebrate eggs and copepods. As adults, they remain primarily planktivorous, feeding on small fishes (including juvenile blue and other rockfishes) as well as crustaceans, polycheates, cephalopods, chaetognaths and jellyfish.

Competition

Black rockfish co-occur with blue and olive rockfishes in the water column and with black-and-yellow rockfish near and on the bottom.

Black rockfish are commonly associated with other nearshore fish species, particularly other rockfishes. No other schooling rockfish was closely associated statistically with black rockfish, but three benthic species, gopher, China, and brown rockfishes, showed an affinity to the same habitat and depth range as black rockfish. It is commonly known among fisherman that localized areas of relatively high abundance in the nearshore area characterize black rockfish distribution in central California.

Critical Habitat

Larval black rockfish are pelagic. Young-of-the-year (approximately 1.5 in.) settle nearshore, generally in the shallower portions of the kelp beds (15 to 40 ft) where they frequent the sand-rock interface, seagrass beds, kelp canopy, midwater column and high-relief rock. They have also been found on artificial reefs, and in bays, estuaries and tide pools.

Adults inhabit the midwater and pelagic areas over high-relief rocky reefs. They are found in and around kelp beds, boulder fields and artificial reefs.

Status of Stocks

In California, no fishery-independent population estimates have been made of black rockfish stocks. Marine Recreational Fisheries Statistical Survey (MRFSS) showed that in Humboldt and Del Norte Counties (northern California), black rockfish comprised from 15 to 31 percent annually of the estimated total marine recreational catch for all fishing modes combined. South of the Eureka area, black rockfish gradually decrease in importance in the recreational catch and are infrequently observed south of Santa Cruz.

 

 

 

 

 

 

China Rockfish

Abbreviated Life History of China Rockfish

(Sebastes nebulosus)


The China rockfish is an attractive rockfish, almost entirely black except for a yellow, or yellow-white stripe that runs from the anterior portion of the dorsal fin, along the lateral line, to the tail.

Distribution, Stock Structure and Migration.

China rockfish occur from Kachemak Bay, northern Gulf of Alaska to Redondo Beach and San Miguel Island in southern California, but they are most abundant from southeastern Alaska to Sonoma County, California. They are found at depths up to 420 ft, but are most common between 30 and 300 ft. The juveniles are pelagic but the adults are sedentary, associated with rocky reefs or cobble. They are residential, traveling less than a meter from their home range, and generally found resting on the bottom or hiding in crevices.

Age and Growth

China rockfish have been aged to a maximum age of 26 yr. Based on a calculated age-length relationship, a 10-in. TL China rockfish is approximately 6-7 yr old and a 12-in. TL fish is approximately 9-10 yr old. A maximum length of 17.9 in. has been recorded for this species.

Reproduction, Fecundity and Seasonality

Off central and northern California, male China rockfish reach reproductive maturity at a total length of 10.2 in. TL and 3 yr of age, while the females reach maturity at 11.0 in. TL and 4 yr of age. Fifty percent of the population of males and females will reach first maturity at 10.6 in. TL and 4 yr of age, and 11.0 in. TL and at 4 yr of age, respectively.

Spawning occurs off central and northern California between January and July, with peak spawning in January. Individual China rockfish spawn once a year. Larvae settle out of the plankton between 1 to 2 months after release.

Natural Mortality

Estimates for natural mortality were not available for China rockfish.

Diseases

No information is available on diseases in China rockfish.

Predator/Prey Relationships

Like grass and kelp rockfish larvae, China rockfish larvae are planktivores. Juveniles eat crustaceans, while the adults eat crustaceans as well as ophiuroids, mollusks, and fish. Juveniles are prey of birds, porpoises, and fishes, including rockfishes, lingcod, cabezon, and salmon. Predators of adult China rockfish include sharks, dolphins, seals, lingcod, and possibly river otters.

Competition

China rockfish are likely to compete with other demersal species like kelp greenling, cabezon, lingcod, and other rockfishes such as grass, quillback, copper, and vermilion, all of which also inhabit rocky areas.

Critical Habitat

Larvae and early juveniles are pelagic but larger juveniles and adults settle on rocky reefs or cobble substrate, most commonly in depths between 30 and 300 ft. Once they settle, individuals may stay on the same reef for years.

Status of Stocks

No formal stock assessment has been completed for this species.

 

Quillback Rockfish

Abbreviated Life History of Quillback Rockfish

(Sebastes maliger)


The quillback rockfish is a component of central and northern California=s nearshore benthic assemblage. Quillback rockfish are relatively small, and are of Astout@ morphology; a characteristic common among nearshore Sebastes found in close association with the bottom. They are usually orange-brown to black in color with a yellow or orange pale area between the eye and pectoral fin.

Distribution, Stock Structure and Migration.

Quillback rockfish are known from the Gulf of Alaska to San Miguel Island in southern California. They are considered common between southeast Alaska and northern California. They are considered a shallow to moderate depth species although they rarely occur to depths of 900 ft.

No stock structure has been determined for quillback in California.

Like other Sebastes of shallow, benthic habitat, individual quillback rockfish are not known to range far. Tagging studies in central California and Washington have shown quillback to be residential (no movement other than diurnal) or to show movement of less than 6 miles. They have also demonstrated homing ability and specific diurnal movement patterns.

Age and Growth

In California, quillback rockfish have been aged to 15 yr, but are known to live longer: They have been aged to 76 yr in Canada. Quillback can grow to 24 inches.

Reproduction, Fecundity and Seasonality

In California, size at first maturity as well as 50% maturity for males is 8.7 in. TL (4 yr.), and for females is 10.2 in. TL (6 yr.) As with all Sebastes , quillback have internal fertilization and are viviparous. In California, mating takes place in the late winter/early spring, and parturition April through July; with a peak in May and June. After roughly one or two months in the plankton, they begin to settle near shore.

Natural Mortality

Natural mortality (M) values have been calculated for quillback rockfish stocks in Washington. It has been calculated to be 0.1253 via tag and recapture methods, and 0.115 via Hencke survivorship/age frequency curve.

Diseases

No information on disease in quillback rockfish was found.

Predator/Prey Relationships

As planktonic larvae, quillback rockfish are known to consume nauplii invertebrate eggs and copepods. After they settle in the shallow, nearshore areas they remain zooplanktivorous and feed on crustaceans. As adults their habit is more benthic, and they are known to feed on a variety of prey such as crustaceans; small fish, including rockfishes and flatfishes; bivalves and fish eggs.

As juveniles, they are preyed upon by fishes, including larger rockfishes (such as yelloweye), lingcod, cabezon and salmon. Various marine birds and pinnipeds take juvenile quillback as well. Adults are also subject to predation by larger piscivorous fishes including some sharks, as well as pinnipeds, and possibly, river otters.

Competition

Though quillback rockfish occur with a host of other nearshore benthic species, no information on competition was found.

Critical Habitat

The larvae of quillback rockfish are planktonic. After about one to two months in the plankton, they begin to settle near shore. Young-of-the-year quillbacks are found among relatively shallow, low-relief rocky substrate and shallow, vegetated habitats such as kelp and eelgrass beds. Juveniles tend to inhabit the very nearshore benthos as well, and are found over both low and high rocky substrate. Adults are most often found in deeper water and are solitary reef-dwellers living in close association with the bottom. They are often seen perched on rocks or taking shelter in crevices and holes. Adults have also been noted to retreat to eelgrass beds at night. Quillback are also associated with the rock-sand interface, but are rarely seen in the open away from suitable cover.

Status of Stocks

No stock assessment has been done for this species. Quillback rockfish are a minor component of the nearshore recreational fishery with decreasing occurrence south of northern California. They are also a component of the nearshore commercial fishery.

 

 

Salmon

 

Lifecycle - From spawning to hatching, migration and growth

Spawning
If you take a walk along a coastal river in British Columbia during the fall or early winter, chances are you will see Pacific salmon.

Salmon lay their eggs in streambed gravel or in spring-fed lake beaches. The female turns on her side, fans her tail back and forth and scoops out a hollow to make a nest or redd in which to lay her eggs. The male then fertilizes the eggs with sperm ( milt ). Sometimes, a number of males join the female at the last minute to fertilize the eggs. At this time, the female covers the nest with gravel. She may build several redds before spawning is complete. It is an exhausting process - all Pacific salmon adults, except steelhead and cutthroat, die shortly after spawning.

Incubation
Salmon eggs develop over the winter, secure within their nest, protected from the cold and all but the most extreme winter storms. In mid or late winter the eggs hatch into tiny fish called alevins . Alevins have huge eyes and a sack-like attachment, which contains the remaining egg yolk. Alevins can be quite active in the spaces between the gravel. In streams of the interior or far north where they can freeze down in to the gravel, alevins are known to swim downward to avoid the ice. The yolk supplies them with food until they emerge from the gravel in the spring and begin to feed.

Fry and Smolts
When alevins emerge as fry in the spring, at only 2 centimetres long, they are vulnerable to predators such as herons, ducks and even robins! While pink and chum fry head for the ocean right away, the other species feed and grow in the stream, river or lake for up to three years before heading out to sea. At this stage in their lives, they are called smolts , measuring up to 12 centimetres in length. A silvery coating develops on the scales to camouflage smolts from predators. This coating also protects them during the transition from freshwater to saltwater habitats. The smolts of all of the species form large schools as they move into the estuaries and near-shore habitats. This behaviour is known to reduce predation.

Adult Salmon
Sooner or later, all salmon find their way to the ocean or coastal waters. Here they feast on an abundant food supply of plankton, crab larvae, shrimp, squid and small fish which enables the salmon to grow quickly. Depending on the species, they spend between one summer and five years at sea. Finally, they begin the journey back to their native streams. Salmon stop eating just before they enter freshwater. From that point until they die after spawning, with the exception of steelhead and cutthroat, salmon live on stored body fats and protein.

One of the marvels of Pacific salmon is the ability to return to the river where they were hatched. Researchers have shown that some salmon actually return to the exact spot where they were hatched! Researchers have studied this phenomenon for years and understand some of the complexities of salmon navigation. To get back to the river, salmon seem to use some combination of the earth&'s magnetic field, celestial navigation, patterns of polarized sunlight and instinctive patterns of movement along the continental shelf and other landmarks. Once they get close to their natal river, salmon seem to use unique odours remembered from when they left as smolts. The migration of some species up rivers, through turbulent waters and over seemingly insurmountable waterfalls has inspired numerous stories of perseverance and courage. By the time salmon finally reach their spawning grounds, their bodies are scarred, their fins are ragged and much of their energy is gone. With spawning, a whole new generation of salmon will hatch to migrate, grow and carry out the lifecycle all over again.

Threats to Pacific Salmon

Salmon face both natural and manmade threats. Natural threats include extreme weather that can produce floods that wash away spawning gravels, landslides that can block rivers and even volcanic eruptions that destroy entire rivers. Pacific salmon are superbly adapted to such habitat disturbances and can quickly recolonize damaged areas. In fact, when the glaciers retreated after the last ice age 11,000 years ago, salmon were confined to a few small refuge areas in the eastern Pacific. Since then they have recolonized and adapted to nearly every stream, river and lake that they can swim to.

Salmon face more serious threats from people than from nature. Prior to European contact, First Nations harvested salmon and there was an abundant supply for their needs. In 1852, the Hudson&'s Bay Company started commercial fishing. By 1870, canned salmon, especially sockeye, was in demand worldwide. Species other than sockeye were often tossed back because canneries did not accept them. The 1900s brought sawmills and logging. Land was cleared throughout much of southern British Columbia often without regard to the effects on rivers and streams. Agriculture, mining and settlement have caused further damage to the habitat that supports salmon. The search for gold in the early 1900s brought placer mining to many areas of interior British Columbia and the Yukon. Placer mining is particularly damaging to salmon because it involves washing and screening large quantities of river gravel, which releases large quantities of sediment that chokes spawning grounds. Intense fisheries developed through the last five decades of the 20 th Century, and some stocks of salmon declined to low levels. Many of those fisheries harvest fish from many populations, some of which could not support intense harvest. Those populations became severely depressed and some vanished.

Currently, improved fisheries management, habitat protection and stock enhancement programs minimize harmful impacts and reverse past damage, but problems still remain. Changing ocean conditions that may be a product of global warming have led to poor survival in the ocean for some populations of salmon. Expanding human populations demand fishing opportunities on one hand, and land and water for agriculture, forestry and towns on the other. This poses numerous challenges for managing and conserving Pacific salmon.

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