Nassau Grouper Epinephelus Striatus Research Articles

Grouper Tales: Use of Acoustic Telemetry to Evaluate Grouper Movements at Western Dry Rocks in the Florida Keys

AbstractThe Western Dry Rocks (WDR) area off Key West, Florida, is an open fishing area that contains a multispecies fish spawning aggregation site, but grouper spawning there has yet to be confirmed. The movements of 18 adult and subadult grouper at WDR were tracked using acoustic telemetry to determine how this area is used by grouper species and whether it contains a grouper spawning aggregation site. Tagged fish consisted of 10 Black Grouper Mycteroperca bonaci, 5 Nassau Grouper Epinephelus striatus, 2 Gag M. microlepis, and 1 Yellowfin Grouper M. venenosa. Overall, tagged grouper were more likely to be present in the WDR array during winter spawning months, with species‐specific seasonal differences. Our results indicated that grouper presence increased during spawning months, although some adults and subadults were present year‐round. Grouper made more movements per day during non‐spawning months compared to spawning months, although the north side of WDR was the most heavily used area, regardless of the time of year. Additionally, spatial graphs of grouper movement suggested that different grouper species utilized different areas of WDR. Increased presence of grouper during spawning months suggests that the WDR area may contain a grouper spawning aggregation site, which would mean that fish species aggregate to spawn at this location year‐round. The success of the Florida Keys fisheries critically depends on the protection of multispecies spawning aggregations like that potentially contained at WDR.

Potential for grouper acoustic competition and partitioning at a multispecies spawning site off Little Cayman, Cayman Islands

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 634:127-146 (2020) - DOI: https://doi.org/10.3354/meps13181 Potential for grouper acoustic competition and partitioning at a multispecies spawning site off Little Cayman, Cayman Islands Katherine C. Wilson1,*, Brice X. Semmens1, Christy V. Pattengill-Semmens2, Croy McCoy3,4, Ana Širović1,5 1Scripps Institution of Oceanography, 8622 Kennel Way, San Diego, California 92037, USA 2Reef Environmental Education Foundation (REEF), PO Box 246, Key Largo, Florida 33037, USA 3Cayman Islands Department of Environment, Box 10202, Grand Cayman KY1-1002, Cayman Islands 4Bangor University, Bangor LL57 2DG, UK 5Texas A&M University Galveston, PO Box 1675, Galveston, Texas 77553, USA 6Present address: NOAA Fisheries Office of Science and Technology, 1315 East West Highway, SIlver Spring, Maryland 20910, USA *Corresponding author: katherine.c.wilson11@gmail.com ABSTRACT: Many fishes produce calls during spawning that aid in species and mate recognition. When multiple sound-producing species inhabit an area, the detection range may decrease and limit call function. Acoustic partitioning, the separation of calls in time, space, or spectral frequency, can minimize interference among species and provide information about fish behavior and ecology, including possible response to increasing anthropogenic noise. We investigated acoustic partitioning among 4 sound-producing epinephelids, Nassau grouper Epinephelus striatus, red hind E. guttatus, black grouper Mycteroperca bonaci, and yellowfin grouper M. venenosa, using passive acoustic data collected at Little Cayman, Cayman Islands, during the spawning season of 2015 to 2017. We measured spectral and temporal features of 9 call types known or presumed to be produced by these fishes to assess frequency partitioning and call discrimination. We assessed call temporal and spatial partitioning using recordings from 2 locations. Differences among call features enabled good discrimination of Nassau grouper and red hind but not black and yellowfin grouper. The median peak frequencies of calls differed but bandwidths shared a common 13 Hz range, resulting in limited partitioning of spectral space. Red hind produced calls with higher frequencies than other species. Black grouper calling peaked before sunset whereas other species’ calling peaked after sunset. Yellowfin grouper calling was prevalent north of other species, suggesting spatial separation. These results indicated separation in space and time between species calls, which aids in acoustic partitioning. When this separation did not occur, unique call structures were present, which may aid in effective intraspecies communication. KEY WORDS: Grouper · Spawning aggregation · Fish bioacoustics · Acoustic niche · Acoustic partitioning Full text in pdf format Supplementary material PreviousNextCite this article as: Wilson KC, Semmens BX, Pattengill-Semmens CV, McCoy C, Širović A (2020) Potential for grouper acoustic competition and partitioning at a multispecies spawning site off Little Cayman, Cayman Islands. Mar Ecol Prog Ser 634:127-146. https://doi.org/10.3354/meps13181 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 634. Online publication date: January 23, 2020 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2020 Inter-Research.

Multiyear Tracking of Nassau Grouper Spawning Migrations

AbstractAn understanding of temporal patterns of migration and spatial connectivity between home ranges and spawning sites is necessary for effective management of species that form transient spawning aggregations. The Nassau Grouper Epinephelus striatus is a Caribbean coral reef fish that displays such spawning aggregations, which have been overfished to the point of threatening the species. Using acoustic telemetry, we examined the size at which Nassau Grouper migrate to spawning aggregations, the timing of migrations, and the distance of migration routes used by Nassau Grouper from within and outside of a large, no‐take marine reserve in the central Bahamas. Fish (total n = 19) were tagged in 2004 (n = 6) and 2005 (n = 13) and were tracked for one to four spawning seasons. Fish that were 54 cm TL or greater made spawning migrations, with all but one migrating southward along the shelf edge of Exuma Sound for a distance of 70 km to over 200 km, usually during the December full moon. Fish typically made one migration annually, which lasted from 1 to 3 weeks, with fish remaining at spawning sites for only 1–2 d; however, when the full moon was early in the spawning season, several fish remained away from their home reefs through two lunar cycles or delayed their migrations by a month, and one fish made two migrations. Fish that were migrating for the first time had slower swimming speeds to spawning sites than did experienced fish, but swimming speeds were similar between the two groups during return migrations, suggesting that their migration behavior was learned. Our results demonstrate that spawning migration patterns for this species may be more variable in The Bahamas than at other Caribbean locations. The present findings also have important implications for the management of the species, including increasing the minimum size limit to 54 cm or larger and the use of both marine protected areas and seasonal closures to rebuild the spawning stock.Received February 1, 2016; accepted July 27, 2016

Length-based indicators of fishery and ecosystem status: Glover's Reef Marine Reserve, Belize

For the spear gun fishery at Glover's Reef, Belize, we used catch length frequencies to infer whether each of the eight most common species was likely to be overfished (spawning stock biomass<target) or experiencing overfishing (fishing mortality rate F>natural mortality rate M). We used Monte Carlo simulations to determine whether the results were sensitive to uncertainty about natural mortality, asymptotic length, growth rate and length at maturity. We found that black grouper Mycteroperca bonaci is overfished, and Nassau grouper Epinephelus striatus, schoolmaster snapper Lutjanus apodus and mutton snapper Lutjanus analis are probably overfished, but hogfish Lachnolaimus maximus, stoplight parrotfish Sparisoma viride, French angelfish Pomacanthus paru and gray angelfish Pomacanthus arcuatus are probably not overfished. All species except French angelfish were experiencing overfishing across a range of life history parameters. Nassau grouper, black grouper and mutton snapper were often caught below the size at maturity Lm. The results were sensitive to different assumed values of the life history parameters. Life history parameters can vary regionally for many reef fishes, and there have been few life history studies in the western Caribbean; such studies would greatly improve estimates of stock status. We also calculated six multispecies indicators of fishery status. The mean length relative to Lm was greater than 1.0 and constant between 2005 and 2011. Mean trophic level, mean maximum size, and fraction piscivores increased between 2005 and 2011, partly due to the fact that parrotfish, previously an important component of the catch, have been prohibited beginning in 2009. Mean catch per unit effort declined. Given that black grouper, Nassau grouper, mutton snapper and schoolmaster snapper are found to be overfished and experiencing overfishing under most values of the life history parameters, we recommend size or catch limits for these species.

Are the last remaining Nassau grouper Epinephelus striatus fisheries sustainable? Status quo in the Bahamas

Nassau grouper Epinephelus striatus is an important species recreationally, commer- cially, and for subsistence in the Bahamas. Within most of the species' range, over-exploitation has led to large declines in abundance and to disappearance of spawning aggregations. Nassau grouper is classified as 'Endangered' on the IUCN Red List of Threatened Species. The popula- tion(s) in the Bahamas is/are considered to be among the few remaining major Nassau grouper populations globally. However, the recent declining trend in the number of fish landed raises con- cerns about the sustainability of the Bahamas' population(s). In this study, we provide an appraisal of the current status of the fisheries and explore the potential effects of different fishery and con- servation management scenarios on the Nassau grouper population and the fisheries. The study uses existing biological and fishery data together with fishers' knowledge on fisheries collated from an interview survey. The results suggest that the population is now fully- to over-exploited and under decline, although this needs to be validated when more fishery and population data have been collected and analyzed. A precautionary approach to managing the Bahamas' Nassau grouper is to maintain spawning aggregation closures, and to improve the monitoring, control, and surveillance to address poaching. Also, fishing mortality rates should be reduced to below the 1998-2001 level during non-spawning aggregation periods. These measures will increase spawn- ing potential and maximize the long-term economic benefits of the fisheries. Other potential threats to the Nassau grouper population, such as the invasion of lionfish, increased use of com- pressors, and the taking of immature fish, should be monitored and assessed.

Sea bottom geomorphology of multi-species spawning aggregation sites in Belize

Large, commercially important coral reef fishes such as Nassau grouper Epinephelus striatus are known to spawn at specific places and times in a so-called transient fish spawning aggre- gation (FSA). Traditional E. striatus spawning sites also serve as multi-species FSA sites. Many sites have been extirpated by overfishing or have shown dramatic declines. The objectives of this paper are to: (1) characterize the sea bottom geomorphology of all known transient FSA sites in Belize; (2) provide an evaluation of the multi-species aspects of known FSA sites; and (3) evaluate a prediction of 2 potential FSA sites based on the relationship between seafloor characteristics and fish aggrega- tions. The reef structures surrounding FSA sites were defined in relation to their depth and proxim- ity to shelf edges, deep water, reef channels, and reef promontory tips. All (n = 14) transient FSAs occurred at convex-shaped reef structures jutting out over steep walls into deep water. All FSA sites were located <100 m from shelf edges and <200 m from reef promontory tips, and at a mean of 78 ± 62 m from 100 m depth. Geomorphologically distinctive features at known FSAs allowed us to iden- tify 2 new multi-species FSA sites exhibiting similar characteristics. All the primary FSA sites in Belize are reef promontories, but the reasons why fish aggregate at these sites remain unclear.

Hormone-Induced Multiple Spawning of Captive Nassau Grouper Broodstock

Abstract During a 5-month period from 3 December 1991 to 28 April 1992, two female Nassau grouper Epinephelus striatus were spawned three times and one female two times by hormone induction. The interval between spawnings for an individual female ranged from 28–75 d. Successful spawnings (fertilization rate > 50%) were induced in females with average oocyte diameters ranging from 517–544 μm by a primary injection of human chorionic gonadotropin (HCG; 1,000 IU/ kg body weight), followed by a second injection (500 IU!kg body weight) after 24 h. Time of strip-spawning ranged from 37–45 h after the first injection and was inversely related to average water temperature (range, 22.4–26.4°C). Mean diameters spawned eggs were 871–959 μm, and the number of eggs spawned per female ranged from 200,000 to 2,000,000. Fertilization and hatching success were 17.9–80.6% and 68.3–90.1 %, respectively. The results demonstrate a reproductive capacity that minimizes broodstock requirements and enhances suitability of the Nas...

Introduction of Hatchery-Reared Nassau Grouper to a Coral Reef Environment

The Nassau grouper Epinephelus striatus has historically supported reef fisheries throughout much of the tropical western Atlantic Ocean. However, fisheries have severely declined in most areas because of overfishing. These declines have inspired efforts to develop culture technology for Nassau grouper and to determine the feasibility of stock enhancement. We first conducted a 128-d dart tag retention study in a concrete raceway with 32 juvenile Nassau grouper reared from eggs. Sixty-nine percent of tags (22 of 32) were retained. Twenty-seven Nassau grouper (579—1,098 g, 309—367 mm total length) were shipped by airfreight to St. Thomas, U.S. Virgin Islands, placed in a holding cage on a coral reef at Saba Island for 15—16 d, and then released. Counts of tagged fish by divers showed an initial decline at the release site during the first month due to dispersal and possible early mortality, followed by gradually decreasing counts over a 9-month period. This study shows that hatchery-reared Nassau grouper can tolerate tagging and survive in the ocean if released at a large size. However, many other questions concerning the feasibility of Nassau grouper restocking remain unanswered. Based on our findings and a review of available information, we consider Nassau grouper stock enhancement to be an option only when simpler management methods for attaining wild stock recovery have failed.