Blue Runner, Caranx crysos
The Blue Runner, Caranx crysos, whose common Spanish name is cojinuda negra, is a common member of the Jack or Carangidae Family, known collectively as jureles and pámpanos in Mexico. Globally, there are seventeen species in the genus Caranx, nine of which are found in Mexican waters, three in the Atlantic and five in the Pacific and one in both oceans.
The Blue Runners have “jack-like” moderately compressed relatively slender rectangular bodies with a depth that is 26 to 30% of standard length. They have an overall light olive to dark blue-green coloration and are silvery to golden ventrally. They have seven pale narrow vertical bars spaced about one inch apart along their sides that fade quickly upon collection. Their head profile is convex with a gentle slope. They have a blunt snout and fairly large eyes set just above the mid-line. Their mouth is small and opens at the front. Their gill cover has a black spot located half-way between their pectoral fin base and the end of their lateral line. All their fins are pale. They have a deeply forked caudal fin and two equally-sized dorsal fins. Their pectoral fins are exceedingly long (a key to identification). They have 35 to 42 gill rakers and 46 to 56 strong prominent scutes. Their pronounced lateral line has a short anterior arch.
The Blue Runners are a pelagic schooling species found both inshore and offshore over reefs and around large man-made offshore structures between the surface and depths of 300 feet. Schools can reach up to 10,000 individuals in size. They reach a maximum length of 70 cm (28 inches) and weight of 5 kg (12 pounds). They are predatory fish that attack schools of small fish inshore and also consume various crustaceans and other invertebrates. They feed exclusively on zooplankton offshore. They are preyed upon by many larger species including birds, dolphins, and fish. Each female releases an average of 40,000 to 1.5 million pelagic eggs annually. Due to their high abundance in the Atlantic they are well studied scientifically and their importance to various fisheries and the ecology of their environment are well understood. They have a lifespan of 11 years.
In Mexican waters the Blue Runners are found in all waters of the Atlantic.
The Blue Runner is very similar in appearance and morphology to the Green Jack, Caranx caballus (41 to 45 gill rakers), which is only found in the Pacific Ocean and its head profile is slightly wider at the eyes (17 to 18% of standard length versus 15 to 16% for the Green Jack).
In North and South America, Blue Runners are caught at levels of 5,000 tons per year taken by haul seines, lampara nets, purse seines, gill nets, and hook and line methods. They are sold either fresh, dried, smoked or as fishmeal, oil, or bait. They are also used as live bait for big game fish (amberjack, billfish, or cobia) as they are very hardy in the bait well and can swim surprisingly fast for long distances on the hook. They are a targeted species of recreational anglers. They are viewed as mediocre table fare as larger specimens are known to contain Cigua Toxin.
Blue Runner, Caranx crysos. Fish caught off the beach at Playa del Carmen, Yucatán, Quintana Roo, February 2016. Length: 25 cm (10 inches). Catch, photo and identification courtesy of George Brinkman, Guelph, Ontario, Canada.
Blue Runner, Caranx crysos. Fish caught from coastal waters off the Dominican Republic, February 2017. Length: 34 cm (13 inches). Catch and photo courtesy of David Haselbauer, Scandia, MN.