About Roncador stearnsii (Steindachner, 1876)
Spotfin croaker, scientifically named Roncador stearnsii (Steindachner, 1876), has an elongated body that is heavier toward the front. The upper profile of its head is steep, slightly curved, and abruptly rounded at the very blunt snout. Its mouth is positioned underneath the head, a placement called subterminal. Its dorsal side is silvery gray, its underside is white, and it may have a bluish blotch near the head. Dark wavy lines run along its sides, and there is a distinct large black spot at the base of its pectoral fin, which is how the fish got its common name. The subterminal mouth, absence of a fleshy barbel, and large black spot at the base of the pectoral fin distinguish spotfin croakers from all other California croakers. Small spotfin croaker, sometimes called "spotties", are occasionally confused with small white croakers, but counting dorsal fin spines will quickly separate the two species: spotfin croaker have 11 or fewer spines, usually ten, while white croaker have 12 to 15 spines. The so-called "golden croaker" is simply a large male spotfin croaker displaying breeding colors. This fish can reach a maximum recorded length of 68 centimetres (27 in) and a typical maximum weight of 4.8 kilograms (10.5 lb); one individual caught in 1951 was reported to weigh 6.8 kilograms (15 lb). Most caught spotfin croaker are small to medium-sized, and the species can reach a maximum age of 24 years. This species occurs from Mazatlán, Mexico, to Point Conception, California, including the Gulf of California. Within California, it is most commonly found south of Los Angeles Harbor. It lives along beaches and in bays over bottoms ranging from coarse sand to heavy mud, at depths between 1 and 15 metres (3.3 to 49.2 ft), and has been recorded at a maximum depth of 22 metres (72 ft). It prefers near-shore depressions and holes. Spotfin croaker travel extensively, but with no fixed pattern, moving frequently between bays. For example, individuals tagged in Los Angeles Harbor were later caught as far south as Oceanside, and spotfin tagged in Newport Bay moved to Alamitos Bay and vice versa. Spotfin croaker eat a wide range of food, including bivalves such as clams and mussels, marine worms, and feed heavily on small crustaceans. Adults have also been observed eating brittle stars and sea stars. Larval spotfin croaker eat invertebrate eggs and zooplankton. They use large, pavement-like pharyngeal, or throat, teeth to crush their food. Male spotfin croaker first reach maturity and spawn at two years old, when they are about 9 inches (23 cm) long. Most females mature at three years old, when they reach 12.5 inches (32 cm) long. All spotfin croaker are mature by four years old, when they reach a size of 14.5 inches (37 cm). The spawning season runs from June to September, and spawning likely occurs offshore, as no ripe individuals have been caught in the surf zone. Juveniles measuring 1 inch (2.5 cm) long appear in the surf zone during fall.
