|Scientific Name:||Cynoscion othonopterus Jordan & Gilbert, 1882|
Cynoscion orthonopterus Jordan & Gilbert, 1882
Cynoscion othonopterum Jordan & Gilbert, 1882
|Red List Category & Criteria:||Vulnerable D2 ver 3.1|
|Assessor(s):||Chao, L., Espinosa, H., Findley, L. & van der Heiden, A.|
|Reviewer(s):||Carpenter, K., Polidoro, B. & Livingstone, S. (Global Marine Species Assessment Team)|
This species is restricted to a few locations in the Gulf of California where it has been historically overfished, and heavy fishing pressure is expected to continue. It is suspected to already be heavily overfished given that it is targeted during spawning aggregations, and a 10 cm decrease in body length has been observed in just four years (1998 to 2002). In addition, juveniles are dependent on river mouths for nurseries, the largest of which has ceased to flow (Colorado River). It is listed as Vulnerable under Criterion D. With additional information on population status and fisheries data, this species should be re-evaluated as it may warrant a more threatened category under Criterion A or B.
|Range Description:||This species is endemic to the Eastern Pacific, and is only known from a few locations in the northern and central Gulf of California. Given its current known distribution and maximum depth of 30 m, it has an area of occupancy estimated to be less than 20,000 km².|
|FAO Marine Fishing Areas:|
Pacific – eastern central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No population information is available for this species. This species became commercially extinct in the 1960s (Román et al. 1998), when river flow to the Gulf effectively ceased. In 1993, a controlled release of Colorado River water dramatically increased flows to the Gulf of California, and in the three years after the release, Cynoscion othonopterus catches increased from 32 to 1,278 metric tons (t) in the fishing village of El Golfo de Santa Clara, Sonora, Mexico (M. Román, unpublished data). However, unpublished fisheries data (Román et al.) between 1998 and 2002 shows a continued decrease in average size of individuals by 10 cm that likely indicates overfishing.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||This benthopelagic species inhabits coastal waters to depths of 30 m. Cynoscion juveniles are often found near river mouths but within this species' distribution, the one large river mouth available for juveniles is the Colorado River which has ceased to flow consistently since the 1960s.|
This species is threatened by overfishing within its very restricted range. Even though it is present in a Marine Protected Area (Biosphere Reserve), it is still fished seasonally during its spawning aggregation. Shrimp trawling activities also capture juveniles as by-catch. Declines in commercial landings have also been at least partially attributed to reduced river flow.
Over the past 40 years, reduction in Colorado River flow due to the construction of upstream dams has all but eliminated nursery habitat for juveniles.The Colorado River Estuary once extended up to 70 km south into the upper Gulf of California, creating a 4000 km2 of fresh and brackish-water habitat in the upper Gulf of California (Carbajal et al. 1997, Lavín and Sánchez 1999). Since the 1960s, the Colorado River has rarely reached the Gulf (Lavín and Sánchez 1999) is now a negative estuary where salinity averages 38‰ in the upper Gulf (Lavín and Sánchez 1999, Calderon-Aguilera et al. 2003).
|Conservation Actions:||This species' distribution falls into the Colorado River Biosphere Reserve in the upper Gulf of California (WDPA 2006). Legislation for this species has been formally in place in Mexico since 2005 (NOM-009-PESC-1993), mandating seasonal closure of fisheries from 1 May to 31 August. However, it is suspected that this timeframe falls outside of the main spawning aggregation period for this species. Future enforcement of seasonal closure is a recommended high priority conservation measure, especially for spawning aggregations.|
|Citation:||Chao, L., Espinosa, H., Findley, L. & van der Heiden, A. 2010. Cynoscion othonopterus. The IUCN Red List of Threatened Species 2010: e.T183682A8157661.Downloaded on 18 December 2017.|
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