Although little fisheries data exist for red hind, Epinephelus guttatus (Linnaeus, 1758) on the Saba Bank, Netherlands Antilles, spawning aggregation characteristics from other populations can be used to assess the health of a red hind spawning population previously undocumented there. In December 2005, a spawning aggregation site for red hind was surveyed on Saba Bank at 17°33.6´N, 63°17.7´W. Red hind aggregated on the northeast edge of the bank, in an area of 0.053 km2 . Spawning occurred in January 2006 during the week prior to and possibly after the full moon. Reproductively developed males and females were collected from December through February, however, in January average fish density increased from 1.46 ± 0.26 fish 100 m–2 to 34.27 ± 2.20 fish 100 m–2 and the M:F sex ratio shifted from 4:1 to unity. Fish were observed exhibiting little territorial or haremic behavior. Gonadosomatic indices in females reached high daily averages in January and February of 15.86 ± 5.4 and 6.93 ± 2.40 respectively, one day prior to the full moon. Average daily water temperature dropped throughout the study period, and during the week prior to the full moon in January, ranged from 26.7 °C to 26.5 °C. Current direction was dominated by tidal fluctuations but during the spawning period was predominantly directed to the southwest. Comparison of spawning population characteristics across red hind aggregation sites in the eastern Caribbean under varying degrees of protection suggests that the Saba Bank aggregation is moderately exploited and should be monitored and more closely managed.
A red hind spawning aggregation was found on the northeast edge of the Saba Bank, a large submerged platform in the leeward Antilles of the Caribbean. The bank, 5 km west of the island of Saba and 140 km southeast of St. Croix, rises from the sea floor 1000 m to form an extensive plateau, over 1600 km2 of which is shallower than 50 m. The bank is entirely enclosed in the Exclusive Economic Zone of the Netherlands Antilles. Fisheries on the Saba Bank, particularly lobster and snapper, are economically important to the small island economy of Saba (pop 1600), employing 50 people and contributing 1.1 million US$ to the gross domestic product. Except for prohibition of foreign fishing vessels however, little fisheries management exists.
Annual spawning aggregations of red hind Epinephelus guttatus form at predictable times and locations and have historically succumbed to overfishing. Monitoring the status and restoration of aggregations is essential for evaluating the effectiveness of fishery management measures. Passive acoustic and diver-based underwater visual census (UVC) techniques were used to develop an efficient method for estimating red hind density from sound production at spawning aggregations. Red hind sound production was recorded from November 2010 to April 2011 at Abrir la Sierra, Puerto Rico. UVC surveys were conducted during the spawning season to assess changes in red hind density over a fixed time and area. Sound recorded from 18:00 to 19:00 h Atlantic Standard Time (UTC − 4) was representative of total daily changes in red hind sound production and was selected for the development of an efficient density estimation model. Pronounced daily changes in sound production and density were observed after the December 2010 and January 2011 full moons. Two hourly sound level measurements were compared to densities estimated by UVC surveys, yielding significant linear regressions, which were used to predict changes in fish density as measured at the aggregation site. Passive acoustic methods allowed to predict changes in red hind density and habitat use at a higher temporal resolution than previously possible with traditional methods. Red hind sound production and inferred densities can be monitored and analyzed efficiently for multiple aggregation sites simultaneously, documenting short-term and long-term changes in red hind densities at spawning aggregation sites and providing important information for the support or development of management strategies.
Many fishes, including groupers, produce sounds associated with mating behavior; recording and analyzing the occurrence of these sounds can provide long time-series records of grouper use of spawning habitat. Red hind Epinephelus guttatus sound production was recorded on spawning aggregation sites off the west coast of Puerto Rico and at Mona Island, Puerto Rico. Audio- video recordings were used to identify a species-specific sound produced by male red hind, most commonly during territorial patrols, and also during interactions with females. This sound is low in frequency (50 to 400 Hz) and consists of a series of pulses repeated at a variable rate. Long-term acoustic recorders were placed off the west coast of Puerto Rico at Abrir La Sierra and at Mona Island to record the timing of red hind sound production from January through March. Red hind sounds were detected at all times of the day, with peaks in sound production just before dusk. Monthly peaks in sound production were evident in each time series, but the monthly peak in sound production at Abrir La Sierra was 6 d later than the peak at Mona Island, suggesting that the timing of spawning of these 2 aggregations, while on a lunar schedule, was not broadly synchronized during this time period. This research lays the groundwork for both long-term monitoring and mapping of red hind spawning sites that will be useful for managing spawning aggregations, especially in remote areas.