|Scientific Name:||Zapteryx exasperata|
|Species Authority:||(Jordan & Gilbert, 1880)|
Platyrhina exasperata Jordan & Gilbert, 1880
|Taxonomic Notes:||There are possible taxonomic problems in tropical latitudes (possible confusion with Zapteryx xyster), which may severely limit the functional range of Z. exasperata (Ebert 2003).|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Bizzarro, J.J. & Kyne, P.M.|
|Reviewer(s):||van Hees, K. & Lawson, J.|
|Contributor(s):||Freedman, R.M., White, C.F. & Lowe, C.G|
|Facilitator/Compiler(s):||Ebert, D.A., Walls, R.H.L. & Dulvy, N.K.|
The Banded Guitarfish (Zapteryx exasperata) is thought to range from central California south to Peru; however its occurrence south of Mazatlán, México is questionable due to possible confusion with the Southern Banded Guitarfish (Zapteryx xyster), a more tropically distributed species. This species inhabits rocky reefs, shallow, sandy lagoons and nearshore waters, from the intertidal zone down to 200 m depth, but mostly at depths between 2.5 and 10 m. This species is taken in artisanal fisheries on the Pacific coast of Baja California and in the Gulf of California, México. In the directed batoid fishery on the Pacific coast of Baja California (in Bahía Almejas), fishermen target aggregations of primarily gravid females during late spring and early summer months in nearshore and inshore nursery grounds. Within the Gulf of California, it is rare in catches (however catch and landings data are scarce outside of Sonora). Exceptions may be during reproductive aggregations and possible large catches by shrimp trawlers, although information on indirect landings by commercial trawls and gillnets is lacking. It is not known if this is relatively uncommon species, as landings would suggest, or if it simply occupies areas that are not heavily fished. To confirm the status of this species, its distribution needs to be accurately documented and abundance data should be obtained at least along the Pacific coast of Baja California and in the Gulf of California. Due to a lack of certainty on geographic range, and a poor understanding of natural abundance, the Banded Guitarfish is assessed as Data Deficient. This species is potentially at threat due to targeting of reproductive aggregations and generally unregulated artisanal fishing across its Mexican range. When further information is obtained the species' conversation status should be reassessed with priority.
|Previously published Red List assessments:|
|Range Description:||The range of the Banded Guitarfish extends from central California to at least Mazatlán, México. The southern extent of its range is not well defined, with records of the Banded Guitarfish extending south through Central America to Peru. These reports further south of Mazatlán are likely sightings of the closely-related Southern Banded Guitarfish (Z. xyster). Therefore, the species likely has a relatively restricted range (Ebert 2003).|
Native:Mexico (Baja California, Baja California Sur, Sinaloa, Sonora); United States (California)
|FAO Marine Fishing Areas:|
Present - origin uncertain:
Pacific – southeast; Pacific – eastern central
|Range Map:||Click here to open the map viewer and explore range.|
There are several lagoons along the Pacific coast of Baja California, which likely serve as important nursery grounds for this species (Ebert 2003). Neonates were recorded at San Ignacio Lagoon, Baja California Sur, but only gravid females have been noted in other embayments (though their function as nursery grounds is almost assured; Villavicencio-Garayzar 1995). Near-term embryos were spontaneously aborted from landings taken in shallow, nearshore waters off central Sonora during late May (R. Hueter et al. unpublished data).
The population size is unknown and there have been no stock assessments for this species; but there appears to be high genetic structuring between the Gulf of California and the Pacific Coast of Baja California. Genetic studies suggest these two groups have limited gene flow and should be treated as separate management units (Castillo-Páez et al. 2014). In general, catch per unit effort (CPUE) was reportedly higher on the Pacific side of Baja California (mean CPUE is nine individuals per trip), compared to the Gulf of California (mean CPUE is 2.67 individuals per trip; Blanco-Parra et al. 2009, Cartamil et al. 2011, Ramirez-Amaro et al. 2013).
On the Pacific coast of Baja California in Laguna Manuela, the species represents 27% of the overall gillnet catch and 12.06% of all identified carcasses from discarded carcass piles, which made it the 4th most common species landed (Cartamil et al. 2011). In the directed batoid fishery on the Pacific coast of Baja California in Bahía Almejas, Baja California fishers target aggregations of primarily gravid females during late spring and early summer months in nearshore and inshore nursery grounds (Villavicencio-Garayzar 1995, Bizzarro 2005). The Banded Guitarfish was reportedly encountered at a CPUE of 0.06-2.86 individuals per vessel per day between 1998 and 2000 (Bizzarro 2005).
In the Gulf of California (state of Sonora), CPUE was seasonally variable between 1998 and 1999, with the highest CPUE being a mean of 1.4 individuals per trip in the spring, and all other seasons reporting mean CPUEs of 0.1-0.4 individuals per trip (Bizzarro et al. 2009a). Overall these low CPUEs in Sonora corresponded to low presence in landings, with the Banded Guitarfish representing <2% of the total percentage of elasmobranch landings (Bizzarro et al. 2009a, Blanco-Parra et al. 2009). On the coast of Baja California Sur, this species was mostly absent from catches sampled in artisanal fishing communities between 1998 and 1999, except in the winter season when it was found to make up 1.2% of the total elasmobranch catches (Bizzarro et al. 2009b).
It is considered rare in southern California (Leet et al. 2001).
|Current Population Trend:||Unknown|
|Habitat and Ecology:|
The Banded Guitarfish inhabits rocky reefs, shallow, sandy lagoons and nearshore waters, from the intertidal zone down to 200 m depth, but mostly depths between 2.5 and 10 m (Feder et al. 1974, Villavicencio-Garayzar 1995, de la Cruz-Aguero et al. 1997, Ebert 2003). Based on fishery landings data, this species appears to exhibit seasonal migrations from nearshore environments in the spring and summer to deeper habitats in the fall and winter (Blanco-Parra et al. 2009). Except during the mating season, individuals are sexually-segregated like many other elasmobranchs (Villavicencio-Garayzar 1995). Females are known to congregate in shallow bays and lagoons from January to August, after which they migrate, likely to deeper waters (Villavicencio-Garayzar 1995, Ebert 2003). Comparatively, the same study found that males were present in embayments (and probably nearshore waters as well) during early spring for copulation and then emigrated while females remained until parturition during July or August (Villavicencio-Garayzar 1995).
Very little information is available for this species outside of its nearshore breeding grounds. It is lecithotrophic viviparous with litter sizes of 2 to 13 young produced annually (Blanco-Parra et al. 2009). There is evidence that larger females produce larger litters (Villavicencio-Garayzar 1995). Mating occurs from the end of March through April, and birthing occurs during July and August, with a gestation period of 5 to 6 months (Bahía Almejas, Baja California Sur, México; Blanco-Parra et al. 2009). The species reaches a maximum size of 97 cm total length (TL; Villavicencio-Garayzar 1995), with females reaching maturity at 57-77 cm TL and males maturing at 64-70 cm TL (Ebert 2003). Generation length is unknown for this species, but its congener Rhinobatos productus, a slightly larger species that occurs within a similar range, has an estimated generation length of 9 years (Timmons and Bray 1997).
|Generation Length (years):||9|
|Use and Trade:||This species is utilized in Mexico.|
This species is taken in artisanal fisheries in the Gulf of California and Baja California, México. Instances of high catches may be during reproductive aggregations and possible large catches by shrimp trawlers. However, information on incidental catch in commercial trawls and gillnets is lacking.Habitat modification may pose a threat to the species as well. Many embayments and estuaries in Sinaloa, México are being modified to accommodate shrimp farming and may limit potential nursery grounds (Hernàndez-Cornejo and Ruiz-Luna 2000). This practice may also be occurring in the southern portion of its assumed range, but no data are available.
In México, a moratorium on the issue of elasmobranch fishing permits was enacted in 1993, but no formal management plan has been implemented for the Banded Guitarfish specifically or most other chondrichthyans in México. New regulations in Mexico limit gillnet fishers to one gillnet per vessel with a minimum mesh size of 15 cm. However, few fishers understood the new regulatory guidelines and even fewer comply (NORMA Oficial Mexicana 2007, Cartamil 2011).
Elasmobranch landings in México and Central America are poorly monitored and lack species-specific details as all batoids are generally termed “manta raya.” Improved clarity in catch records would provide an essential basis for detecting fishery trends. Expanded monitoring of elasmobranch catches in México, Central America and South America is necessary to provide valuable species- and sex-specific information and improve our limited knowledge of the extent of these fisheries. Life history information on age, growth, longevity, movement patterns, habitat use, and further reproductive studies throughout the range of the Banded Guitarfish is also critical. Fishery-independent surveys of this and other demersal elasmobranchs are necessary to provide estimates of abundance and biomass.
|Citation:||Bizzarro, J.J. & Kyne, P.M. 2015. Zapteryx exasperata. The IUCN Red List of Threatened Species 2015: e.T60177A80673370.Downloaded on 30 August 2016.|
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