Turtle Journal

Terrapins as “Catch of the Day”

Perhaps ironic, pehaps not; the “Catch of the Day” tank in the Discovery Center of the Conservancy of Southwest Florida features diamondback terrapins.  Inside the aquarium with three adult terrapins, a few crabs and some local fish is a large crab trap.  You may be aware that vast numbers of diamondback terrapins have been and still are killed each year as by-catch in crab traps all along the Atlantic and Gulf coasts.  Hungry and curious turtles become attracted by the bait (and the captured crabs), enter the trap and cannot escape.  Unlike crabs, terrapins are air breathers and are drowned by the thousands in residential, commercial and “ghost” traps from Massachusetts to Texas.

Female Terrapin Climbs Crab Trap

The crab trap shown in the Conservancy’s “Catch of the Day” tank is equipped with TEDs (turtle excluder devices) that prevent most terrapins from entering the trap, while allowing crabs to gain easy access.  TEDs prove beneficial for harvesters since they keep aggressive and hungry turtles from eating the trap’s bait first and then consuming the captured crabs for dessert.  The height of the TED opening excludes larger turtles with their thicker girth from gaining access, while allowing crabs to enter with no difficulty.

Female Terrapin and Crab Trap

Because terrapins exhibit significant gender dimorphism with females twice the length and four times the mass of males, TEDs preferentially protect mature, breeding females with their much thicker girth.  Males and juvenile turtles of both genders are more likely to become trapped and drown in crab traps.  Use of traps without TEDs substantially alters the gender ratio within a population.

You will have noted that the Conservancy keeps the water level below the TED-equipped entrances.  Since this trap is not fully submerged as crab traps normally are, even in the unlikely case that a curious turtle climbed the walls and forced its entry, it would not drown.

Terrapins LOVE Calamari

A perfect illustration of why crab harvesters benefit from excluding terrapins from their traps came by accident at the Conservancy while Turtle Journal’s Sue Wieber Nourse was shooting footage (see above).  Someone placed a squid in the “Catch of the Day” tank for the crabs to feed on, but mistakenly put it within reach of the terrapins.  While not their normal food at the Conservancy, the temptation of fresh calamari was too overwhelming for a terrapin to resist.  Bon appetite!

This entry was posted on Tuesday, February 23rd, 2010 at 11:00 am and is filed under Habitat, Marine Species, Turtles. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.