from the December 7, 2014
Newsletter issued from Río Lagartos, on the north-central coast of Yucatán, MÉXICO
On a flamingo-viewing trip up Ría Lagartos Estuary, I was with a young guide who likes to take along dead fish to toss into the water in case there's a Common Black Hawk or crocodile who might be enticed to come closer so the tourists can snap spectacular pictures. That day he'd forgotten his fish. However, as we passed by the pier beneath the big bridge on the road between Río Lagartos and Las Coloradas, a fisherman had just dragged in his throw-net and was discarding fish he didn't want. When the young guide asked if he could have one of the throwaways, the fisherman tossed a slender, silvery, six-inch one (15cm) into the boat. Above, you can see it dying on the boat's floor.
Later the fish was identified by comparing the picture with those at the fine fish-ID website at http://www.snorkelstj.com/
There, one of the first species to pop up when I looked in the "Silvery or White Fish" category looked just like what's in our picture. It was the White Mullet, MUGIL CUREMA, described at the above website as most often seen in schools racing back and forth in shallow water, searching for small organisms on sandy bottoms and on plants and algae. That's exactly what they seemed to be doing around us.
White Mullet are an abundant, widely distributed species, found generally along coasts in temperate and tropical seas of the Western Hemisphere. A reason for the fish's success is that it thrives in a wide range of water conditions, ranging from freshwater to hypersaline (saltier than ocean water) coastal waters -- everyplace from ocean beaches, bays, lagoons, salt marshes and mangrove swamps to tidal rivers. Especially young fish, which this one appears to be, are known to invade estuaries and coastal lagoons like the Ría Lagartos Estuary.
White mullet gulp up mud containing algae, plankton, and plant and animal detritus which the fish's gut can deal with thanks largely to its uncommonly muscular gizzard.
You can imagine the value of these abundant little fish to larger predators, both fish and birds.