Sargo

Abstract: The Salton Sea is a 93 000 ha saline lake fed by drainage water from more than 283 000 ha of irrigated lands in the Imperial and Coachella valleys of California. A total of 21 composite samples of four recreationally important fish species — bairdiella (Bairdiella icistia), orangemouth corvina (Cynoscion xanthulus), sargo (Anisotremus davidsoni), and Mozambique tilapia (Tilapia mossambica) —collected there were analyzed for 14 elements. Twelve of these elements were detected in one or more of the samples: As, B, Co, Cu, Fe, Hg, Mo, Ni, Pb, Se, V, and Zn. Cadmium and Tl were not detected. The ranges in concentrations of elements in the skinless fillets of bairdiella, corvina, and sargo, and in whole bodies of all four fishes were comparable to levels that are typically measured in saltwater fishes. Only Se concentrations were elevated (as much as 14 µg g−1 dry weight in both fillets and whole bodies) in this series of samples. Elevated concentrations of Se have already led to public health advisories concerning the consumption of fish and might eventually cause the demise of fish populations from toxic effects.

Abstract: Size series of 116 Anisotremus davidsonii (2.2-24.9 mm) and 13 1 Xenisfius calijorniensis (2.241.7 mm) from field collections were examined for pigmentation, and most specimens were measured to determine morphometric characteristics. Subsets of 39 A. davidsonii (2.923.6 mm) and 25 A'. calijorniensis (2.7-24.1 mm) were cleared and stained to examine skeletal development. Pigment in both species is largely limited to the ventrum and to the dorsal surface of the gut and swimbladder throughout larval development. Both species subsequently develop rather heavy dorsal and dorsolateral pigment; small juveniles display the longitudinal stripes that are well known in juvenile Haemulinae. Both species are moderately slender, with preanal length roughly half of body length. Development in both is gradual, with no marked changes in proportions. Both look like typical haemulines. Skeletal development differs little from that described for other haemulines. Bones of the jaws, operculum, and suspensorium are among the first to ossify, usually before notochord flexion. Ossification of neural and haemal arches and spines and vertebral centra, except the urostyle, is anterior to posterior. Pterygiophores and soft rays form first in the middle of the dorsal and anal fins in both species; addition is both anterior and posterior. Addition of dorsal spines begins posteriorly, but then may continue from anterior to posterior. Larval sargo and salema are distinguished from similar larvae off California and northern Baja California primarily by a combination of myomere count and ventral pigment on the tail. Larval sargo typically have pigment on the peritoneum just anterior to the liver, while larval salema do not. Larval salema usually have a melanophore under the anterior hindbrain, while preflexion stage larval sargo usually do not. After notochord flexion sargo are deeper-bodied than salema. Dorsal fin ray counts allow easy separation of postflexion and older sargo (14-15) from salema (1213).

Abstract: The Salton Sea is an endorheic, 980-km2 salt lake in the Sonoran Desert of southern California. The historical fish community switched from freshwater to marine species as salinity increased due to evaporation and brackish water inflows. Three species, bairdiella (Bairdiella icistia), orangemouth corvina (Cynoscion xanthulus), and sargo (Anisotremus davidsoni), established from introductions beginning in 1929. Thirty-four marine fish species from the northern Gulf of California were introduced between 1929 and 1956. During the late 1960s and early 1970s, a hybrid tilapia (Oreochromis mossambicus x O. urolepis hornorum) invaded the Salton Sea and became dominant by numbers and weight. Research has shown that nearshore and estuarine areas have the highest catch rates of tilapia (over 11 kg/50 m net/h). Orangemouth corvina, bairdiella, sargo, and the hybrid tilapia grew faster, but had shorter life spans than conspecifics elsewhere, and Salton Sea conspecifics of 50 years ago. All four species aggregated alo...