Northern rock sole
Encyclopedia
The Northern rock sole, Lepidopsetta polyxystra, is a flatfish
of the family Pleuronectidae
. It is a demersal fish that lives on sand, mud and gravel bottoms at depths of up to 700 metres (2,296.6 ft), though it is most commonly found between 19 and 246 m (62.3 and 807.1 ft). Its native habitat is the temperate waters of the northern Pacific
, from Puget Sound
to Alaska
(overlapping the range of the rock sole
), the Aleutian Islands and across the Bering Sea
to the Kuril Islands
and the Sea of Okhotsk
(overlapping the range of the dusky sole
). Males grow up to 69 centimetres (27.2 in) in length, whilst females can reach 49 centimetres (19.3 in). The maximum recorded lifespan is 18 years.
, Lepidopsetta bilineata, were considered to be a single species under the genus
Lepidopsetta
, but work by Orr & Matarese published in 2000 reorganised the genus into three separate taxa
.
As a result of this reclassification and renaming, the rock sole L. bilineata may be referred to as the "southern" rock sole, in order to avoid confusion with the Northern rock sole L. polyxystra.
.
polychaete
s and amphipods
.
s, Alaska pollock
, yellowfin sole
, Pacific halibut
and Pacific cod
.
in winter through to early spring. Eggs are demersal and stick to the surface on which they are laid; hatching takes from 6 to 25 days.
fisheries
in the Bering Sea and Gulf of Alaska
. Although it was overfished
in the 1960s stocks have recovered, and the biomass
of Northern rock sole in the Bering Sea and Aleutian Islands fishery is now estimated to be very high, at twice the level required to support maximum sustainable yield
. In 2008 the estimated Northern rock sole biomass in the Gulf of Alaska fishery was some 102,303 tons, compared to catches ranging from 453 tons in 2004 to 4,330 tons in 2006.
Northern rock sole fishing off the coast of the United States is managed by the North Pacific Fishery Management Council, one of eight U.S. Regional Fishery Management Councils
.
Flatfish
The flatfish are an order of ray-finned fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development...
of the family Pleuronectidae
Pleuronectidae
Righteye flounders are a family, Pleuronectidae, of flounders. They are called "righteye flounders" because most species lie on the sea bottom on their left side, with both eyes on the right side. The Paralichthyidae are the opposite, with their eyes on the left side.Their dorsal and anal fins are...
. It is a demersal fish that lives on sand, mud and gravel bottoms at depths of up to 700 metres (2,296.6 ft), though it is most commonly found between 19 and 246 m (62.3 and 807.1 ft). Its native habitat is the temperate waters of the northern Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, from Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
to Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
(overlapping the range of the rock sole
Rock sole
The rock sole, Lepidopsetta bilineata, is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on sand and gravel bottoms at depths of up to , though it is most commonly found between . Its native habitat is the temperate waters of the northern Pacific, from Baja California to...
), the Aleutian Islands and across the Bering Sea
Bering Sea
The Bering Sea is a marginal sea of the Pacific Ocean. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves....
to the Kuril Islands
Kuril Islands
The Kuril Islands , in Russia's Sakhalin Oblast region, form a volcanic archipelago that stretches approximately northeast from Hokkaidō, Japan, to Kamchatka, Russia, separating the Sea of Okhotsk from the North Pacific Ocean. There are 56 islands and many more minor rocks. It consists of Greater...
and the Sea of Okhotsk
Sea of Okhotsk
The Sea of Okhotsk is a marginal sea of the western Pacific Ocean, lying between the Kamchatka Peninsula on the east, the Kuril Islands on the southeast, the island of Hokkaidō to the far south, the island of Sakhalin along the west, and a long stretch of eastern Siberian coast along the west and...
(overlapping the range of the dusky sole
Dusky sole
The dusky sole, Lepidopsetta mochigarei, is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on bottoms in the temperate waters of the northwest Pacific, from the Korean peninsula to the southern Sea of Okhotsk. It grows up to in length....
). Males grow up to 69 centimetres (27.2 in) in length, whilst females can reach 49 centimetres (19.3 in). The maximum recorded lifespan is 18 years.
Taxonomy and Nomenclature
Prior to 2000 the Northern rock sole and the rock soleRock sole
The rock sole, Lepidopsetta bilineata, is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on sand and gravel bottoms at depths of up to , though it is most commonly found between . Its native habitat is the temperate waters of the northern Pacific, from Baja California to...
, Lepidopsetta bilineata, were considered to be a single species under the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Lepidopsetta
Lepidopsetta
Lepidopsetta is a genus of fish in the Pleuronectidae family.Since it was erected by William Orville Ayres in 1862 it has taken in Platessa bilineata, Platichthys umbrosus, Isopsetta isolepsis, Lepidopsetta mochigarei, Lepidopsetta bilineata, Lepidopsetta bilineata bilineata, Lepidopsetta bilineata...
, but work by Orr & Matarese published in 2000 reorganised the genus into three separate taxa
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
.
As a result of this reclassification and renaming, the rock sole L. bilineata may be referred to as the "southern" rock sole, in order to avoid confusion with the Northern rock sole L. polyxystra.
Role in ecosystem
The Northern rock sole occupies a moderately high trophic level in the food chainFood chain
A food web depicts feeding connections in an ecological community. Ecologists can broadly lump all life forms into one of two categories called trophic levels: 1) the autotrophs, and 2) the heterotrophs...
.
Diet
The diet of the Northern rock sole consists mainly of zoobenthosBenthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
polychaete
Polychaete
The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...
s and amphipods
Amphipoda
Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. The name amphipoda means "different-footed", and refers to the different forms of appendages, unlike isopods, where all the legs are alike. Of the 7,000 species, 5,500 are classified...
.
Predators
Northern rock sole are eaten by marine mammals and other fish, including sharkShark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s, Alaska pollock
Alaska pollock
Alaska pollock or walleye pollock is a North Pacific species of the cod family Gadidae. While related to the common Atlantic pollock species of the same family, the Alaska pollock is not a member of the same Pollachius genus.The Norwegian pollock , a rare fish of Norwegian waters, may actually be...
, yellowfin sole
Yellowfin sole
The yellowfin sole, Limanda aspera, is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on soft, sandy bottoms at depths of up to , though it is most commonly found at depths of around...
, Pacific halibut
Pacific halibut
The Pacific halibut is found on the continental shelf of the North Pacific Ocean and Bering sea. They are demersal, living on or near the bottom. The halibut is among the largest teleost fish in the world. Halibut are strong swimmers and are able to migrate long distances...
and Pacific cod
Pacific Cod
The Pacific cod, Gadus macrocephalus, is an important commercial food species. It is also known as gray cod, gray goo, gray wolf, grayest or grayfish. It has three separate dorsal fins, and the catfish-like whiskers on its lower jaw. In appearance, it is similar to the Atlantic Cod...
.
Reproduction
Northern rock sole reach reproductive maturity at between 4 and 7 years old, and spawnSpawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
in winter through to early spring. Eggs are demersal and stick to the surface on which they are laid; hatching takes from 6 to 25 days.
Commercial fishing
Northern rock sole is fished commercially, and forms an important part of two trawlTrawling
Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net that is used for trawling is called a trawl....
fisheries
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
in the Bering Sea and Gulf of Alaska
Gulf of Alaska
The Gulf of Alaska is an arm of the Pacific Ocean defined by the curve of the southern coast of Alaska, stretching from the Alaska Peninsula and Kodiak Island in the west to the Alexander Archipelago in the east, where Glacier Bay and the Inside Passage are found.The entire shoreline of the Gulf is...
. Although it was overfished
Overfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
in the 1960s stocks have recovered, and the biomass
Biomass (ecology)
Biomass, in ecology, is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community. It can include microorganisms,...
of Northern rock sole in the Bering Sea and Aleutian Islands fishery is now estimated to be very high, at twice the level required to support maximum sustainable yield
Maximum sustainable yield
In population ecology and economics, maximum sustainable yield or MSY is, theoretically, the largest yield that can be taken from a species' stock over an indefinite period...
. In 2008 the estimated Northern rock sole biomass in the Gulf of Alaska fishery was some 102,303 tons, compared to catches ranging from 453 tons in 2004 to 4,330 tons in 2006.
Northern rock sole fishing off the coast of the United States is managed by the North Pacific Fishery Management Council, one of eight U.S. Regional Fishery Management Councils
U.S. Regional Fishery Management Councils
The eight U.S. regional fishery management councils are the primary forums for developing conservation and management measures for U.S. marine fisheries. The regional councils recommend management measures for fisheries in the Exclusive Economic Zone ; which are subject to approval and implemented...
.