Longjaw Mudsucker, Gillichthys mirabilis
Longjaw Mudsucker, Gillichthys mirabilis. Fish caught from a brackish intertidal lagoon in San Diego, California, August 2019. Length: 8.9 cm (3.5 inches). Catch, photograph and identification courtesy of George Brinkman, Guelph, Ontario, Canada. Note that the photograph is taken in an aquarium type-setting with the live fish place in a tank a technique that affords a photograph of a fish with is fins extended.
Longjaw Mudsucker, Gillichthys mirabilis. Fish caught from a brackish intertidal lagoon in San Diego California, October 2018. Length: 9.1 cm (3.6 inches). Catch, photograph, and identification courtesy of Ben Cantrell, San Diego, California.
The Longjaw Mudsucker, Gillichthys mirabilis, is a member of the Goby or Gobiidae Family, and is known in Mexico as chupalodo grande. Globally, there are three species in the genus Gillichthys, and all three are found in Mexican waters of the Pacific Ocean.
The Longjaw Mudsucker has an elongated heavy body with a broad and flat blunt head that has small eyes on top that are widely spaced, a point snout, and an extremely large terminal mouth that has a long upper jaw that reaches the gill openings equipped with small conical teeth. They are dark brown dorsally in color and transition to yellow ventrally with a faint pattern of vertical bars that are more prominent in juveniles; the juveniles also have a dark blotch posterior of the first dorsal fin. Their anal fin has a short base with 1 spine and 10 or 11 rays; their caudal peduncle is large and the fin is rounded; their first dorsal fin is small with 4 to 8 spines; their second dorsal in larger with 1 spine and 11 or 12 rays; their pectoral fins are broad and rounded with 15 to 23 rays; and, their pelvic fins are fused into a sucking disc. They are covered with small scales.
The Longjaw Mudsucker is a small shallow-water benthopelagic species that is one of the most abundant fishes in the intertidal salt-marsh habitat. They are found in burrows in tidal flats, bays and coastal sloughs with mud bottoms at depths up to 6 m (20 feet). They can survive in salt water that is between 9oC (48oF) and 35oC (95oF) but cannot survive in fresh water for long periods of time. They have the ability to survive out of water of short periods of time having the ability to gulp air. They reach a maximum length of 21 cm (8.3 inches). They are omnivores consuming small fishes such as the California Killifish, Arrow Goby and Topsmelt and numerous invertebrates including algae, amphipods and isopods. Reproduction is oviparous with the females laying between 8,000 and 27,000 eggs several times per year in nests built by the males which are then guarded by the males for 10 to 12 days until they hatch into pelagic larvae. They have life spans of up to two years.
The Longjaw Mudsucker is a resident of Mexican waters of the Pacific Ocean but has a limited distribution being found only along the coast along the West Coast of Baja north of Magdalena Bay, Baja California Sur.
The Longjaw Mudsucker is a straightforward identification being the only Mudsucker found north of Magdalena Bay along the central and northwest coasts of the Baja with the exception of the Shadow Goby, Quietula y-cauda (maximum size 7.0 cm; series of large spots along the flank) and the Yellowfin Goby, Acanthogobius flavimanus (small mouth that ends well before the eyes).
From a conservation perspective the Longjaw Mudsucker is currently considered to be of Least Concern with stable, widely distributed populations. They have been used regionally in central Arizona and the lower Colorado River as a live bait as they can be transported in packed moist algae and survive for 6 to 8 days and will not reproduce in fresh-water. They were successfully transplanted into the Salton Sea in 1930.