Shark guide probes uncharted waters


While a lone fin gliding at the surface of the water is enough to clear swimming areas and rates T.V. news coverage, sharks have more to fear from humans than vice versa. Along with other highly migratory species–tunas and billfishes–shark populations have been depleted partly by overfishing and partly by natural factors. Saving these economically valuable fishes is important but not simple, since they cover thousands of miles of ocean territory in search of food.

Difficulties in identifying these creatures for stock assessment and for understanding biological and behavioral characteristics prompted the National Marine Fisheries Service (NOAA Fisheries) and Rhode Island Sea Grant to produce a 124-page guide that will help users distinguish among 44 highly migratory species that inhabit the Atlantic Ocean and Gulf of Mexico.

According to author Margo Schulze-Haugen, NOAA Fisheries fishery management specialist, the Guide to Sharks, Tunas & Billfishes of the U.S. Atlantic & Gulf of Mexico "is different from previous guides because it focuses on how to identify species while the fish is still in the water. Many guides rely on internal characteristics (which require that the fish be dead) or counting of body parts (which require that the fish be on board the vessel for some period of time), in addition to external characteristics. The intent with our emphasis on external characteristics (seen often very quickly as the fish swims around) is to increase species-specific identifications without associated mortality."

In order to focus on external characteristics, the authors–Schulze-Haugen, Tony Corey, Rhode Island Sea Grant communicator, and Nancy Kohler, Apex Predators Program chief, NOAA Fisheries Narragansett Laboratory–decided to use photographs to aid in identification.

Corey says that "Photos are hard to come by. These animals are protected because they're rare or sparsely reported or poorly understood. So, our major challenge was tracking down photos sharp and distinctive enough to allow people to compare what they see in the book to what they see in the water."

In addition to the photographs, the guide offers at-a-glance physical descriptions, habitat and distribution information, side-by-side comparisons of similar species, and information about reducing the risk of shark attack. Species-specific experts have reviewed the content for accuracy.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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