|Scientific Name:||Scomberomorus concolor (Lockington, 1879)|
Chriomitra concolor Lockington, 1879
|Red List Category & Criteria:||Vulnerable A4cd ver 3.1|
|Assessor(s):||Collette, B., Acero, A., Boustany, A., Canales Ramirez, C., Cardenas, G., Carpenter, K.E., Di Natale, A., Die, D., Fox, W., Graves, J., Hinton, M., Juan Jorda, M., Minte Vera, C., Miyabe, N., Montano Cruz, R., Nelson, R., Restrepo, V., Schaefer, K., Schratwieser, J., Serra, R. & Yanez, E.|
|Reviewer(s):||Russell, B., Findley, L., Walker, H., Lea, B. & Polidoro, B.|
The extent of occurrence of this species is inferred to have reduced by more than 80% based on both historical and new information. Prior to 1961 there were records of this species in California and there is strong evidence that this species no longer occurs outside of the Gulf of California. Furthermore, within the Gulf of California, at least since the 1980s, the range of this species has retracted further to its present limits in the central and northern part of the Gulf of California. A greater than 80% reduction in the population is inferred over the past 40 years based both on the reduction in range and from the current levels of exploitation. Although the reduction in range occurred before the time window of three generation lengths (12 years), it is an indication that it is vulnerable to overfishing. Most of the population data available are mixed with Scomberomorus sierra. However, an analysis by the Mexican Instituto Nacional de Pesca in 2002 showed that with current fishing effort is expected to lead to a decline of 40% within the next 10 years unless fishing effort is reduced. As there are no indications of decline of fishing effort, this species is listed as Vulnerable.
|Previously published Red List assessments:|
|Range Description:||This species is endemic to the Eastern Pacific, with two well separated populations, at least at some point in time (B. Collette, pers. comm 2011). Historically, one population occurred from Monterey Bay, California as far south as the US/Mexican border. However, the only extant population is currently restricted to the upper two-thirds of the Gulf of California (Collette 1995). Historically, this species probably had a continuous distribution from California, around Baja and into the Gulf of California (B. Collette, pers.comm. 2011). The present distribution is now limited to the central and northern part of the Gulf of California, only as far south as Bahia de Concepcion (Romero et al. 1994).|
The initial diminution of this species' range began between 1880 and 1920 (Fitch 1949). Over the last 20 years, very few specimens have been found outside of the current known range. There have possibly been only three records in the outer coast of California/Baja California for this species since 1968 (B. Collette pers comm 2011). However, CICIMAR records exist in the Gulf of California as late as 1993 from Loreto.
Possibly extinct:United States
|FAO Marine Fishing Areas:|
Pacific – eastern central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species was commercially caught in the 1870s and 1880s in Monterrey Bay, California, and was considered abundant in the Gulf of California in the 1970s (Collette and Russo 1985).|
In the Gulf of California, this species is caught with Scomberomorus sierra, mainly using gillnets in areas close to the coast. Catches are reported as a combined group ("sierras") and therefore, it is not possible to determine a population trend for this species. However, catch data from Instituto Nacional de la Pesca, Mexico (2002) was used to forecast the probability of decline in this species population in the northern Gulf of Mexico based on projected effort. If effort were to continue the same as in 2002, the stock was predicted to decline 40% over the next 10 years. There is no indication that there have been declines in the effort in this fishery since 2002 (R. Nelson pers comm. 2011).
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||This species is an epipelagic, neritic species. It feeds on euphosiids and clupieids (Valdovino Jacobo et al. 2006). Its biology is almost completely unknown. It occurs along the upper east coast of the Gulf of California in the fall months in shallow estuaries, and spawning occurs in late spring and early summer. This species may be a colder water fish than S. sierra, and may retreat to deep waters in summer. It spawns and swims with S. sierra. It moves from a feeding zone in the central Gulf of California from October to May, to a spawning zone in the northern Gulf of California from May to August (Valdovino Jacobo et al. 2006). The best place to currently find this species is in the spring around Isla San Jorge, 50 km south of Puerto Penasco.|
This species has a sex ratio of 1:1. Based on otolith ageing, the maximum age is eight years (Valdovino Jacobo et al. 2006). Based on the length-weight curve published by Valdovino Jacobo et al. (2006), the length at 50% maturity is 36.5 cm fork length (FL) at three years. The generation length is therefore estimated to be 3.8 years.
|Movement patterns:||Full Migrant|
|Use and Trade:||This species has been intensively fished for many decades.|
This species global population is at risk of collapse (Quinonez-Velazquez and Montemayor-Lopez 2002). There is an important commercial fishery for both this species and S. sierra in the area where S. concolor occurs. The fishery is apparently having severe effects on the remnant of the S. concolor population. The commercial fishery operates from November to April in shallow coastal waters, bays, and estuaries and the combined catch of both species is 4,500 tons per year. The main method of harvesting this species is using gillnets. Both species are also caught by sport fishers.
The species spawns primarily in the northern Gulf of California, were there has been significant habitat loss due to cessation of flow from the Colorado River. It is important to note that two other highly threatened species occur in the area, the Totoaba (Toatoaba macdonaldi, family Sciaenidae) and the Vaquita (Phocoena sinus), a porpoise (Jamarillo-Legorreta and Taylor 2010, Jefferson 2010).
|Conservation Actions:||There are no known conservation measures for this species. Restrictions on the gill net fishery for Totoaba in 1975 (Jaramillo-Legorreta and Taylor 2010) may have provided some conservation benefit to this species. There is an urgent need for monitoring of this species, and for catch data to be dissagregated from S. sierra.|
|Citation:||Collette, B., Acero, A., Boustany, A., Canales Ramirez, C., Cardenas, G., Carpenter, K.E., Di Natale, A., Die, D., Fox, W., Graves, J., Hinton, M., Juan Jorda, M., Minte Vera, C., Miyabe, N., Montano Cruz, R., Nelson, R., Restrepo, V., Schaefer, K., Schratwieser, J., Serra, R. & Yanez, E. 2011. Scomberomorus concolor. The IUCN Red List of Threatened Species 2011: e.T20047A9138383.Downloaded on 20 April 2018.|