''Sebastes diaconus'', the deacon rockfish, is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of marine
ray-finned fish
Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species.
The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...
belonging to the subfamily
Sebastinae
Sebastinae is a subfamily of marine fish belonging to the family Scorpaenidae in the order Scorpaeniformes. Their common names include rockfishes, rock perches, ocean perches, sea perches, thornyheads, scorpionfishes, sea ruffes and rockcods. De ...
, the rockfishes, part of the
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Scorpaenidae. It is found in the eastern Pacific Ocean.
Discovery
![Sebastes mystinus1](https://upload.wikimedia.org/wikipedia/commons/6/68/Sebastes_mystinus1.jpg)
Between 2002 and 2004,
phylogeographic
Phylogeography is the study of the historical processes that may be responsible for the past to present geographic distributions of genealogical lineages. This is accomplished by considering the geographic distribution of individuals in light of ge ...
research on
blue rockfish (''Sebastes mystinus'') identified a distinct genetic subpopulation, which was sampled between
Cape Mendocino
Cape Mendocino (Spanish: ''Cabo Mendocino'', meaning "Cape of Mendoza"), which is located approximately north of San Francisco, is located on the Lost Coast entirely within Humboldt County, California, United States. At 124° 24' 34" W longitude ...
in northern California and Neah Bay, Washington.
Subsequent research identified further genetic evidence supporting this distinct subpopulation, as well as demographic differences and evidence for reproductive isolation.
The subpopulation was cited as an example of
incipient speciation
Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...
.
In 2015, distinct morphological traits were identified for the northern subpopulation and it was
recognized as a distinct species, classified as ''Sebastes diaconus''.
Etymology
The
specific epithet ''diaconus'' (deacon) refers to an 'acolyte', which is a reference to the specific epithet of the blue rockfish, ''mystinus'', which means 'priest' in Latin. Like the two species, an acolyte and priest are similar in appearance.
Description
The deacon rockfish has been described as a cryptic species that is difficult to distinguish from the blue rockfish.
The deacon rockfish however has more visible stripes in its coloration, whereas the blue rockfish has a 'blotchy' color pattern.
As such, prior to the
formal classification of the species, the deacon rockfish was referred to as the 'blue-sided rockfish' and the blue rockfish was referred to as the 'blue-blotched rockfish'.
The shape of the mouth and front of the face also differs subtly between the two species, with the deacon rockfish exhibiting a longer lower jaw, which results in an underbite.
Under dissection, sexually mature female deacon rockfish also have a small pink or cream colored ovary, whereas mature female blue rockfish have a large orange ovary.
The shape of sagittal
otoliths
An otolith ( grc-gre, ὠτο-, ' ear + , ', a stone), also called statoconium or otoconium or statolith, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The sa ...
has been found to subtly differ between males and females, which may indicate
secondary sexual dimorphism.
Genetics
Genetic differences have been identified between male and female deacon rockfish using
RAD sequencing.
Such differences may reflect the evolution of
sex chromosomes
A sex chromosome (also referred to as an allosome, heterotypical chromosome, gonosome, heterochromosome, or idiochromosome) is a chromosome that differs from an ordinary autosome in form, size, and behavior. The human sex chromosomes, a typical ...
in the species or
psueuoautosomal regions within the genome (see
wider discussion of sex chromosome evolution), or
intralocus sexual conflict Intralocus sexual conflict is a type of sexual conflict that occurs when a genetic locus harbours alleles which have opposing effects on the fitness of each sex, such that one allele improves the fitness of males (at the expense of females), while ...
, although the function and evolutionary significance of these genetic sites is currently uncertain.
A potential
PCR-RFLP genetic sex marker developed for
gopher rockfish
The gopher rockfish (''Sebastes carnatus''), also known as the gopher sea perch, is a species of marine ray-finned fish belonging to the subfamily Sebastinae, the rockfishes, part of the Family (biology), family Scorpaenidae. It is found in the e ...
does not successfully distinguish male and female deacon rockfish.
Distribution and habitat
The deacon rockfish is found on rocky reefs and offshore areas from northern California to southern British Columbia.
The species is
sympatric with the blue rockfish in northern California and Oregon.
Female deacon rockfish can exhibit a high level of residency, showing
site fidelity to a particular reef and inhabiting a small
home range
A home range is the area in which an animal lives and moves on a periodic basis. It is related to the concept of an animal's territory which is the area that is actively defended. The concept of a home range was introduced by W. H. Burt in 1943. He ...
.
However, females may relocate depending upon daily and seasonal movement patterns, seasonally occurring
hypoxia, and prey preferences for planktonic organisms.
Ecology
Deacon rockfish may be adapted to
diurnal hunting on small, transparent
plankton
Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...
.
Individuals have been found to ingest gelatinous zooplankton such as the colonial tunicates ''
Pyrosoma atlanticum
''Pyrosoma atlanticum'' is a pelagic species of marine colonial tunicate in the class Thaliacea found in temperate waters worldwide. The name of the genus comes from the Greek words ''pyros'' meaning 'fire' and ''soma'' meaning 'body', referring ...
'', the hydrozoan ''
Velella velella
''Velella'' is a monospecific genus of hydrozoa in the Porpitidae family. Its only known species is ''Velella velella'', a cosmopolitan free-floating hydrozoan that lives on the surface of the open ocean. It is commonly known by the names sea r ...
'', and the ctenophore ''
Pleurobrachia bachei
''Pleurobrachia bachei'' is a member of the phylum Ctenophora and is commonly referred to as the Pacific sea gooseberry. These comb jellies are often mistaken for medusoid Cnidaria, but lack stinging cells.
History
Traditionally, Ctenophora has ...
'', as well as small planktonic crustaceans such as crab
zoeae and megalopae and pelagic amphipods.
Fishing and management
Deacon rockfish are caught both commercially and recreationally in Oregon.
In 2017, the stock assessment for Oregon and California combined deacon rockfish and blue rockfish for management purposes.
The stock assessment estimated the combined populations in California to have declined rapidly in the 1970s and 1980s to a low point in 1995 and then increased to a point close to the management target.
The stocks in Oregon were estimated as having never experienced the same intensity of fishing as in California with spawning biomass remaining above the management target throughout the history of fishing.
In Oregon, nearshore and offshore populations of deacon rockfish are ''de facto'' managed as separate stocks in order to comply with wider regulations on ''Sebastes'' rockfish fishing, although
population genetic
Population genetics is a subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and popu ...
evidence does not support this distinction.
References
External links
Deacon Rockfish, Oregon Department of Fish and WildlifeDeacon Rockfish, Washington Department of Fish and WildlifeMeet the Deacon Rockfish, Oregon Marine Reserves
*
*
{{Taxonbar, from=Q21298154
diaconus
Taxa named by Benjamin W. Frable
Taxa named by David Wolfe Wagman
Taxa named by Taylor N. Frierson
Taxa named by Andres Aguilar
Taxa named by Brian L. Sidlauskas
Fish described in 2015
Fish of the Pacific Ocean