Totoaba Forensic Identification: Specific-Primers Assay Provides Short-Time Results for a Sharpen Law Enforcement

Illegal shipments representing more than 1500 adult totoabas and nearly 8 million dollars were seized over the last three years by both United States and Mexican authorities. The high black-market value of its swim-bladder, coupled with the logistic handicaps for effective surveillance and law enforcement at the extensive Biosphere Reserve where this critically endangered sciaenid fish spawns, encourages poaching and hampers population recovery. MtDNA sequencing is the only effective and efficient genetic forensic test to unambiguously identify totoaba out from a wide variety of commercial fish exploited in the region, thus delaying and sometimes precluding proper law enforcement. Here we present a simple PCR-electrophoresis/qPCR assay targeting a distinctive 260 pb totoaba/bahaba mtDNA control region. We tested different tissues (bladder, blood, fin clips, muscle and skin) submitted to a variety of treatments (fresh, frozen, dried, boiled and rotten) in totoaba and other common commercially fished species from the area.  The method proved to be efficient and highly specific; all totoaba DNA samples, including highly degraded ones and those mixed with DNA from other species were positively identified. Further validation should provide field agents with a valuable tool to determine, in less than 3 hours, if a suspicious product came from totoaba.