Hydroacoustic evaluation of spawning red hind (Epinephelus guttatus) aggregations along the coast of Puerto Rico in 2002 and 2003

Red hind (Epinephelus guttatus) have been overfished in the Caribbean and were included with seven other regional grouper species deemed vulnerable to risk of extinction. The Puerto Rico Department of Natural and EnvironmentalResources desired to map spawning red hind aggregations within commonwealth waters as part of their resource management program for the species. Mobile hydroacoustic surveys were conducted over 3-day periods in 2002 and 2003,indexed to the full moon phase in February or March when red hind were known to aggregate. Four vessels concurrentlysampled the southwest, south, and southeast coasts of Puerto Rico in 2002. In 2003, three vessels conducted complementary surveys of the northwest, north, and northeast coasts of the island, completing a circuit of the coastal shelf-spawning habitat. These surveys indicated that red hind spawning aggregations were prevalent along the south and west coasts, and sparse along the north coast during the survey periods. Highest spawning red hindconcentrations were observed in three areas offshore of the west coast of Puerto Rico, around Mona and Desecheo islands(20,443 and 10,559 fish/km2, respectively) and in the Bajo de Cico seasonal closed area (4,544 fish/km2). Following both 2002 and 2003 surveys, a series of controlledacoustic measurements of known local fish species in net pens were conducted to assess the mean target strength(acoustic backscatter) of each group. Ten species of fish were measured, including red hind (E. guttatus), coney (E. fulvus), white grunt (Haemulon plumieri), pluma (Calamus pennatula), blue tang (Acanthurus coeruleus), squirrel fish (Holocentrus spp.), black durgeon (Melichtyhs niger), ocean file fish (Canthidermis sufflamen), ocean surgeon fish (Acanthurus bahianus), and butter grouper (Mycteroperca spp.). In general, the mean target strength results from the caged fish experiments were in agreement with published target strength length relationships, with the exception ofwhite grunt and pluma.

Bibliographic Details

Main Authors:	Johnston, Samuel V., Rivera, Jose A., Rosario, Aida, Timko, Mark A., Nealson, Patrick A., Kumagai, Kevin K.
Format:	book_section biblioteca
Language:	English
Published:	NOAA 2006
Subjects:	Management, Ecology, Fisheries,
Online Access:	http://hdl.handle.net/1834/20285
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