The ryanodine receptor (RyR) has been found to play a salient role in the transduction of muscle membrane potential to the production of force in a muscle cell. We have determined that the transcript that encodes for the channel region of the RyR retains an intron in both blue marlin and yellowfin tuna. The regions in question have been amplified from fast- and slow-twitch fiber type muscle and genomic DNA of blue marlin and yellowfin tuna. The results indicate that a 73 base pair intron is retained in fast-twitch muscle and genomic DNA of both fish. These PCR products were then cloned and sequenced. A multi-sequence alignment analysis confirmed our PCR results.