Raja inornata 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Chondrichthyes Rajiformes Rajidae

Scientific Name: Raja inornata Jordan & Gilbert, 1881
Common Name(s):
English California Skate
Raja jordani Garman, 1885
Taxonomic Source(s): Eschmeyer, W.N., Fricke, R. and Van der Laan, R. (eds). 2016. Catalog of Fishes: genera, species, references. Updated 1 July 2016. Available at: (Accessed: 1 July 2016).
Taxonomic Notes: This skate is often misidentified with other hardnose skates from the northeast and eastern central Pacific.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2016
Date Assessed: 2014-09-27
Assessor(s): Nehmens, M.C., Robinson, H.J., Ebert, D.A. & Cailliet, G.M.
Reviewer(s): Wegner, N.C. & Lawson, J.
Facilitator/Compiler(s): Kyne, P.M., Walls, R.H.L. & Dulvy, N.K.
The California Skate (Raja inornata) is found at depths of 17–1,600 m on the continental shelf of the Northeast Pacific, but is most common from 58–231 m. It occurs from the Straits of Juan de Fuca, Canada southwards to central Baja California and the Gulf of California, Mexico. On the United States west coast the preferred habitat of this skate is on the continental shelf off San Francisco Bay stretching north to Mendocino and south to Monterey.

Historically, this species was retained as bycatch in commercial longline and trawl fisheries, and marketed for human consumption in the United States. In 2007 trawl fishing effort in California was reduced following the implementation of a network of marine protected areas, likely reducing the bycatch of this species. Although fisheries-independent surveys have been carried out since 2001 on the west coast of the United States, these have not provided enough information to conduct a full stock assessment for this species, though the number of individuals surveyed over time has been stable. This skate is currently managed in the United States as part of the west coast Ground Fishery Management Plan (which includes Washington, Oregon and California).

In Mexico, this species is a part of a skate assemblage and is retained as bycatch in the hake trawl fishery. There is no management in place in Mexico to regulate or monitor catches or landings. While a comprehensive life history study has been conducted in the Gulf of California, there is little information on catches and landings in these waters.

Due to having a life history that can likely sustain moderate fishing pressure, as well as the species-specific monitoring plan in place for this species for the majority of its range, and the reduction in fishing pressure in California, this species is assessed as Least Concern. In Mexico this species is entirely unregulated, and appears to be rarely encountered by Gulf of California fishing communities. This may be due to either natural rarity within these waters or low encounter rates. We suggest more information be collected on the status of the population in Mexican waters.
Previously published Red List assessments:

Geographic Range [top]

Range Description:

The California Skate is found along the northeast Pacific, ranging from the Straits of Juan de Fuca off British Colombia, Canada through Washington, Oregon, and California, USA to central Baja California, Mexico. A habitat suitability probability profile shows that this species is most suited to the continental shelf waters off San Francisco Bay, ranging from the Mendocino area to Monterey Bay (Bizzarro et al. 2014). It is also reported in the waters of the Gulf of California (Miller and Lea 1972, McEachran and Notobartolo di Sciara 1995, Benson et al. 2001).

Countries occurrence:
Canada (British Columbia); Mexico (Baja California, Baja California Sur, Sonora); United States (California, Oregon, Washington)
FAO Marine Fishing Areas:
Pacific – eastern central; Pacific – northeast
Additional data:
Lower depth limit (metres):671
Upper depth limit (metres):17
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Historically, along the west coast of the United States, skate landings were not identified to species level. Landings of "unspecified skates" (which included the California Skate) declined from ~577 t and ~633 t in 2000 and 2001 to ~82 t in 2002. Landings then fluctuated between ~12 t and ~95 t from 2003-2005 (California Department of Fish and Wildlife 2007). In 2013, the amount of reported catch for the California Skate in particular was 5.9 kg, with 15.6 t reported for “unspecified skate,” however the latter category may have also included the California Skate given that this species is reportedly challenging to correctly identify (California Department of Fish and Wildlife 2000-2014).

Current management by the federal groundfish monitoring plan along the west coast of the United States considers the California Skate to be a "data-limited stock" due to insufficient data available to generate a formal stock assessment. These limited data show that the number of individuals encountered in surveys has remained low and relatively stable since these species-specific data became available in 2001 (NMFS 2012).

No population or trends data are available for this species in Mexico. Only two individuals were encountered in Sonora (Gulf of Mexico) during surveys of artisanal fishing communities between 1998 and 1999 (Bizzarro et al. 2009a), and none were reported during artisanal fishing community surveys along the eastern coast of Baja California Sur (Gulf of Mexico) between 1998 and 1999 (Bizzarro et al. 2009b).
Current Population Trend:Stable
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:The California Skate is primarily a continental shelf species that is found on soft bottoms at depths of 17-1,600 m (Miller and Lea 1972, Ebert 2003, Love et al. 2005), but is most common along the west coast of the United States at depths of 58-231 m in waters ranging from 8.2-9.6°C (Bizzarro et al. 2014). Off of central California it has most commonly been encountered at an average depth of 105 m (James et al. 2014).

Males are reported to mature at about 47 cm total length (TL) and females at about 52 cm TL (Ebert 2003). In the Gulf of California, size at maturation is slightly smaller, males at 45 cm (TL) and females 50 cm (TL) with age at first maturity 2.4 yrs and 2.9 yrs, respectively (Castillo-Geniz 2007). The maximum reported size is 76 cm TL (Jordan and Gilbert 1881) with maximum ages of 7 years for males and 9 years for females in the Gulf of California (Castillo-Geniz 2007). This species is oviparous with an annual reproductive cycle peaking in the fall from September to November (Castillo-Geniz 2007). Size at birth is 15–23 cm TL (Ebert 2003). Generation length is estimated to be 5.95 years (calculated from parameters in Castillo-Geniz 2007).
Generation Length (years):5.95

Use and Trade [top]

Use and Trade: This species is marketed for human consumption.

Threats [top]

Major Threat(s): In the United States, this species was previously retained as bycatch in commercial longline and trawl fisheries (Martin and Zorzi 1993) and was considered one of three commercially important skate species in California, marketed for human consumption (Roedel and Ripley 1950, Martin and Zorzi 1993). Skate catches (not identified to species level) have dropped dramatically in California. Given that this species appears to occur primarily on the continental shelf and these fisheries operated in deeper continental slope waters, the California Skate likely has not been as affected by these historically high catches as other species may have been, such as the Longnose Skate (Raja rhina). However, this skate is still often misidentified due to sexual dimorphism and the similarity in appearance to other skates within the same region (Ebert 2003, Bizzarro et al. 2014).

In the Gulf of California, Mexico, the skate assemblage is retained as bycatch in the hake trawl fishery, and no management is in place to regulate and monitor catch rates.

Conservation Actions [top]

Conservation Actions: On the United States west coast (Washington, Oregon and California), this species is included in a federal Groundfish Fishery Management Plan, along with Big Skate (Beringraja binoculata) and Longnose Skate (Raja rhina). Additionally, in California, a network of 29 marine protected areas (MPAs) were implemented in 2007 under California's Marine Life Protection Act, representing approximately 204 square miles (~18%) of state waters in the central coast region (California Department of Fish and Wildlife 2015). Due to these MPAs, most trawlers are restricted to operating in deeper waters, and only in central and northern California. As a result, fishing effort in the California trawl fishery has been reduced, and catches of this species have also likely been reduced.

Citation: Nehmens, M.C., Robinson, H.J., Ebert, D.A. & Cailliet, G.M. 2016. Raja inornata. The IUCN Red List of Threatened Species 2016: e.T161466A80676778. . Downloaded on 21 October 2017.
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