Scientists Discover How Tiny, Transparent Spiny Lobsters Travel in Caribbean Waters

The spiny lobster doesn't look appetizing when you see it in the water. With its rough carapace and small front claws, this species hides beneath reef overhangs in the Caribbean. Yet this creature alone is responsible for generating $1 billion annually, making it one of the most valuable species to fish in the region. Now, scientists are learning a little bit more about the spiny lobster after studying how its young are dispersed far and wide in the ocean water.

Because of their small claws, spiny lobsters are mainly harvested for their meaty tails. In fact, most products that are marketed as "lobster tails" actually come from this particular species. Fishermen harvest them either by diving or using wooden, plastic or metal traps.

While these creatures stay around one location as adults, though, they can travel across miles of ocean when they're young--or at least that's what scientists believed. The lobster's larvae ride currents to journey far afield in order to find the most suitable habitat for their adult lives. This makes it important for the fishery to chart the spread of these larvae.

"Spiny lobster have extraordinary larvae with a prolonged planktonic existence that can last from five months to nearly a year, which confer them with high dispersal potential and complex pelagic pathways," said Claire Paris, one of the researchers, in a news release. "Despite such challenges in documenting their pathways in the open ocean, just like hurricane models that help to reduce the 'cone of uncertainty,' in this case we are improving settlement predictions by simulating large numbers of spawning events and tracking virtual larvae undergoing deep vertical migrations."

In order to examine the spread of the spiny lobster, the researchers used data from laboratory studies, mail surveys and published works in order to parameterize an individual-based model of larval connectivity, the Connectivity Modeling System (CMS). In order to verify the findings made with the model, the scientists then conducted two independent studies that studied larval dispersal.

So what did they find? It turns out that the prevailing Caribbean current may actually not be the best way to transport larvae long distances. In fact, the scientists found that powerful currents entrain and push larvae out of the system. The larvae that ultimately settle spend little time within these currents, instead moving to deeper depths as they age.

"Despite some expected degree of ocean mixing in the region, we found relatively high levels of larvae settling back to their place of origin," said Mark Butler of Old Dominion University in a news release. "This was surprising for larvae that spend up to 12 months traveling in the plankton. But even more surprising was that these simple larval behaviors added to the model also enhanced population connectivity by preventing larvae from behind flushed out of the system."

The findings don't just show larval dispersion for its own sake, though. It could provide the information that the fishery needs to help with better management policies. This, in turn, could encourage sustainable practices that could result in a healthier population.

The findings are published in the journal PLOS One.